Article

Predicting Body Size with Life History Models

May 1986
BioScience 36(5)

May 1986
36(5)

Authors:

University of California, Riverside

Sexual dimorphism explains residual variance around the survival-reproduction tradeoff in lizards: Implications for sexual conflict over life-history evolution

Article

Full-text available

Jul 2019

The tradeoff between survival and reproduction is a central feature of life‐history variation, but few studies have sought to explain why females of some species exhibit relatively lower survival than expected for a given level of reproductive effort. Intralocus sexual conflict theory proposes that sex differences in selection on survival and reproductive effort may, by virtue of shared genes underlying these components of fitness, prevent females from optimizing this life‐history tradeoff. To test this hypothesis, we used a phylogenetically based comparative analysis of published estimates for mean annual survival and reproductive effort from females of 82 lizard species to (1) characterize the tradeoff between survival and reproduction, and (2) test whether variation around this tradeoff is explained by sexual size dimorphism (SSD), a potential proxy for sexual conflict over life‐history traits. Across species, we found a strong negative correlation between mean annual survival and reproductive effort, confirming this classic life‐history tradeoff. Although residual variance around this tradeoff is unrelated to the absolute magnitude of SSD, it is strongly related to the direction of SSD. Specifically, we found that females have lower survival than expected for a given level of reproductive effort in female‐larger species, whereas they have higher survival than expected in male‐larger species. Given that female‐larger SSD is thought to reflect selection for increased fecundity, our results suggest that intralocus sexual conflict may be particularly likely to constrain female life‐history evolution in situations where increased reproductive effort is favored, but the phenotypes that facilitate this increase (e.g., body size) are constrained by antagonistic selection on males. This article is protected by copyright. All rights reserved

BERGMANN SIZE CLINES: A SIMPLE EXPLANATION FOR THEIR OCCURRENCE IN ECTOTHERMS

Article

Jun 1996
EVOLUTION

Wayne A Van Voorhies

In general ectothermic organisms grow larger at both lower temperatures and higher latitudes. Adult size in the soil nematode Caenorhabditis elegans reared at 10°C was approximately 33% greater than worms grown at 25°C. Nematode egg size and fish red blood cell size showed similar size increases at lower temperatures. These results indicate that body size differences in many ectotherms may simply be a consequence of developmental processes that cause cells to grow larger at lower temperatures. This would provide a general explanation for the increased size of ectotherms at lower temperatures independent of species-specific ecology.

Factors Influencing Growth Variability in Three Northern Alberta Populations of Yellow Perch (Perca flavescens)

Article

Jan 2016

This study examined drivers of yellow perch (Perca flavescens) growth in lakes near the northern limit of the species. Three northeast Alberta lakes were surveyed in 1996-1997 and 2009-2010. In the initial survey, the three lakes displayed the full range of perch growth from high density, stunted fish (~10,000 fish/ha, 15 cm), to a low density population that grew to trophy size (~100 fish/ha, 30 cm). In 2009-2010, a repeat survey was conducted to verify if between lake growth differences endured over time and elucidate potential causes of between lake growth variations. Two of the study lakes maintained consistent population demographics and community structure between the surveys while the fish assemblage and perch growth changed significantly at one lake between the surveys. In this lake (Mildred Lake) the community structure changed as two top-piscivore species established throughout and perch density decreased concomitantly. In response, perch showed a significant increase in maximum size (from 20 to 30 cm) and condition factor. Other possible causes of growth variation were also investigated; differences in diet, or an ontogenetic shift to piscivory appeared to have little influence on perch growth variation. Additionally, differences in genetic ancestry (as measured using DNA microsatellites), were not related to growth differences. Perch density, controlled by predation, appeared to be the dominant factor influencing growth differences over time and between lakes.

Reproduction of Lake Trout Morphotypes at Isle Royale in Northern Lake Superior

Article

Jan 2017

The reproductive biology of male and female lean, siscowet, redfin, and humper Lake Trout Salvelinus namaycush was assessed by measuring the gonadosomatic index (GSI) and by histological analysis of the gonads over 2 years from spring to fall at sites surrounding Isle Royale National Park, Lake Superior. Whole livers, otoliths, and ovaries were also collected to measure hepatosomatic index (HSI), age, and fecundity. In general, GSIs increased from spring to summer in male and female siscowets, leans, redfins, and humpers, and this was accompanied by a large increase in the number of vitellogenic (>2.0 mm) follicles in females. Postspawned ovaries and regressing testes were predominant in all morphotypes by October but were also observed in September, indicating that some spawning occurred at least by September. Further, preovulatory siscowet females (GSIs > 10) and siscowet males with fully mature and even regressing testes were observed in the spring and summer, indicating that spawning occurs at least in the spring and fall in siscowets at Isle Royale. For all morphotypes, average male HSIs were significantly lower than female HSIs. Absolute fecundity was positively related to size and age for all morphotypes. Humpers had the lowest absolute fecundity. Leans, redfins, and siscowets had similar fecundity relationships. The results conclusively demonstrate that deepwater siscowet Lake Trout reproduce at least during the spring and fall at Isle Royale and that leans, humpers, and redfins reproduce during the fall. In lakes that exhibit sympatric populations of deepwater and shallow-water ecotypes of Arctic Char Salvelinus alpinus, the deepwater form also spawns in both spring and fall. Our data and those on Arctic Char suggest that there is an adaptive strategy for maintaining alternative spawning times in the deepwater ecotypes in these populations. Received June 20, 2016; accepted November 2, 2016

A Long-Term Study of Coachella Fringe-Toed Lizards, Uma inornata, Reveals Seasonal and Annual Variation in Size and Growth

Article

Full-text available

Jul 2023

Productivity of warm deserts is highly correlated with rainfall. We analyzed body size data from a 35-yr study of Coachella Fringe-Toed Lizards, Uma inornata, to reveal precipitation-related differences among years both in growth and in the length–mass relationship (LMR). The LMR is a linear function enabling comparison of regression coefficients among groups. Adult male U. inornata were significantly larger and their maximum size differed substantially from that of females. Comparing regression coefficients of LMR between sexes revealed equal slopes, although intercepts differed slightly but significantly. We treated the sexes independently to test for seasonal and rainfall differences. Comparing seasonal differences among adults revealed that slopes were not parallel. Regression coefficients predicted that individuals weighed more in spring than in fall, which we attribute to winter rainfall. This was corroborated by recapture data. LMR slopes for extreme dry, extreme wet, and typical rainfall years were parallel, but the elevation for typical years differed significantly from both dry and wet years: they were heavier in typical years. Growth was slower in dry years than in wet or typical years. Differences in growth rates affect time to maturity. We used the production relation model of juvenile growth to estimate time to minimum reproductive size. Time to maturity is doubled during dry years in comparison with wet years (542 vs. 288 d for females, 400 vs. 200 d for males). Together, delayed maturity and predicted future increases in drought frequency and intensity imply conservation concerns for this protected species.

Aging is selected for, adaptive and programmed. 10. Population regulation by density-dependent fecundity/longevity trade-offs

Preprint

Full-text available

Dec 2022

Kurt Heininger

Is leaf fluctuating asymmetry related to plant and leaf size in Miconia albicans, a common Melastomataceae species?

Article

Full-text available

Jun 2022

Fluctuating asymmetry, defined as random differences between the two sides of a symmetrical structure, has been often related to development stress in both plants and animals. In plants, leaf fluctuating asymmetry has been related to stresses such as pollution and fire and may also be related to leaf growth and herbivory rates. We assessed whether leaf fluctuating asymmetry is related to plant and leaf size in Miconia albicans (Sw.) Triana (Melastomataceae), a common multi-stem Neotropical shrub, in a Brazilian savanna area. We collected 15 leaves from each of 70 individuals, and measured fluctuating asymmetry as the difference in area between the right and left sides of the leaves using the central vein as reference. To avoid spurious results due to measurement error, the division along the central vein was performed independently by three researchers. We also measured the basal area and height of each stem of the plant individuals. We used linear models to assess the relations between leaf fluctuating asymmetry, plant size and leaf size. No consistent relations were observed between leaf fluctuating asymmetry and plant size, as the analyses performed on the fluctuating asymmetry values obtained by the different researchers showed different results. However, relative fluctuating asymmetry values, obtained by dividing the fluctuating asymmetry by the total leaf area, tended to be smaller in larger leaves. It thus appears that, in the study species, fluctuating asymmetry is related to the developmental conditions faced by the individual leaves and not by the plant as a whole.

Relative effects of environmental variation and fishing on the demography and ecology of tropical wrasses

Thesis

Full-text available

Nov 2020

Jake Lowe

One of the greatest challenges faced by fishery managers and ecologists is determining the degree to which natural variation in population dynamics (i.e., species abundance and life history traits) are modified by fishing. Multiscale sampling that encompasses temporal and spatial variation in anthropogenic and environmental factors are key to understanding mechanisms that drive population dynamics. To date, our understanding of these processes has been hindered by a lack of spatially explicit demographic information for many fishery targeted species. This is particularly true for multi-species, Indo-Pacific coral reef fisheries that are under increasing levels of exploitation. For example, across Indo-Pacific reefs, large-bodied wrasses are common components of reef fish assemblages and are exposed to increasing levels of exploitation, yet little is known regarding their life histories or drivers of population variability. This thesis was designed to assess the relative effects of environmental variation and fishery exploitation on the demography and ecology of tropical wrasses both spatially and temporally, to determine patterns of demographic variation and population drivers among and within species.

Body and Wing Allometries Reveal Flight-Fecundity Tradeoff in Response to Larval Provisioning in Osmia lignaria (Hymenoptera: Megachilidae)

Article

Full-text available

May 2021
J INSECT SCI

Variation in body size has important implications for physical performance and fitness. For insects, adult size and morphology are determined by larval growth and metamorphosis. Female blue orchard bees, Osmia lignaria, (Say) provision a finite quantity of food to their offspring. In this study, we asked how provision-dependent variation in size changes adult morphology. We performed a diet manipulation in which some larvae were starved in the final instar and some were given unlimited food. We examined the consequences on adult morphology in two ways. First, allometric relationships between major body regions (head, thorax, abdomen) and total body mass were measured to determine relative growth of these structures. Second, morphometrics that are critical for flight (wing area, wing loading, and extra flight power index) were quantified. Head and thorax mass had hyperallometric relationships with body size, indicating these parts become disproportionately large in adults when larvae are given copious provisions. However, abdominal mass and wing area increased hypoallometrically with body size. Thus, large adults had disproportionately lighter abdomens and smaller wing areas than smaller adults. Though both males and females followed these general patterns, allometric patterns were affected by sex. For flight metrics, small adults had reduced wing loading and an increased extra flight power index. These results suggest that diet quantity alters development in ways that affect the morphometric trait relationships in adult O. lignaria and may lead to functional differences in performance.

ECOLOGÍA REPRODUCTIVA DE UN ENSAMBLE DE SAURIOS DEL VALLE DE CHILECITO - LA RIOJA, ARGENTINA

Thesis

Dec 2015

Gabriela A Gallardo

The study of the lizards´reproductive ecology allows to test the hypothesis about the evolutionary mechanisms that cause diversification in the life stories. A lizard ensemble represented by species of the Liolamidae, Teiidae and Tropiduridae, was investigated. The study was conducted in an area in good condition, located in the Mount biome, from September 2009 to May 2011. The reproductive phenology and the cycle of fat bodies was studied; it was also analyzed the relation between the climatic characteristics and the reproductive events. Other aspects of the reproductive ecology that were analyzed are the species reproductive production and the sexual dimorphism. Also the description of the male and female gonads was made at histologic level. The environmental difference between the two periods of research (2009 – 2010 and 2010 – 2011), represented a natural experiment, since the first period was dry in relation to the second. The active period in the analyzed species extended between September and April of the following year: Tropidurus etheridgei, Aurivela tergolaevigata and Teius teyou, restringed their activities to spring and summer before hibernating while Liolaemidae (Liolaemus cuyanus, L. laurenti and L. koslowskyi) were also active during the first part of Autumn. The species adjusted their reproduction to the warmest seasons, spring- summer. However, at the begining of autumn, during the wettest period, Liolaemus individuals with reproductive activity were seen. Unlike males, the female ones complete the gonadal cycle in the same period; they are also receptive less time than males. The interspecific differences, underlie in the temporal distribution and duration of the reproductive steps. The reproductive phenology was different among Teiidae species: Aurivela tergolaevigata is a facultative producer that could extend the the reproductive period according to food availability; vitelogénesis is positively related to maximun humidity. Teius teyou adjusts its reproduction to spring. The ovarian cycle of sandstone species Liolaemus cuyanus and L. laurenti are developed in summer; in Tropidurus etheridgei and L. koslowsky extend from November to February of the next year. Anyway, newborn recruitment startedat the begining of summer and in some species was later in the same season. Heliophane explained the gonadal development in males in all the species. Lipid reserve in fat bodies raised at the end of summer and the begining of autumn; a part of these fats were used by animals during the Winter months; remaining lipids were used for female reproduction during the nest spring; ovigenean females lacked abdominal fat. In males the largest fat reserve was simultaneous with the presence of regressive testicles. In the studied species the size of the litter varies and the amount of eggs increased with the long snout sewer of the mother. In the wet season, there was a larger quantity of receptive females. In terms of sexual dimorphism in body size, the differences are manifested in the proportions of the main segments of the body: females have larger abdominal cavities and males have bigger heads. The morphological differences between males and females, common to all species of ensemble highlight the role of sexual selection and selection for fertility in populations. In the species studied, the litter size increases with long snout sewer of the mother, reason by which it is proposed that the sexual differences in the length of the trunk would be a direct target of selection for fertility; the increase in abdominal volume in females allows them to house larger litters and increase the chances of successful reproduction. The larger of the males head must have a competitive advantage in fights by females or in the def enses of the territory. Sexual differences in the body features and their associated functions, reflect the balance of selective forces acting both in males and females. Ecological factors, both the climatic variables and the availability of food, probably the competitive interactions and habitat niches, would have a key role in the ecology of the reproduction of the species that make up the ensamble. In addition, other variables such as the size of the body and phylogenetic histories also impose limits on the reproductive attributes.

Natural mortality estimation using tree-based ensemble learning models

Article

Jul 2020
ICES J MAR SCI

Empirical studies are popular in estimating fish natural mortality rate (M). However, these empirical methods derive M from other life-history parameters and are often perceived as being less reliable than direct methods. To improve the predictive performance and reliability of empirical methods, we develop ensemble learning models, including bagging trees, random forests, and boosting trees, to predict M based on a dataset of 256 records of both Chondrichthyes and Osteichthyes. Three common life-history parameters are used as predictors: the maximum age and two growth parameters (growth coefficient and asymptotic length). In addition, taxonomic variable class is included to distinguish Chondrichthyes and Osteichthyes. Results indicate that tree-based ensemble learning models significantly improve the accuracy of M estimate, compared to the traditional statistical regression models and the basic regression tree model. Among ensemble learning models, boosting trees and random forests perform best on the training dataset, but the former performs a slightly better on the test dataset. We develop four boosting trees models for estimating M based on varying life-history parameters, and an R package is provided for interested readers to estimate M of their new species.

Direct and indirect effect of cannibalism and intraguild predation in the two sibling Harmonia ladybird beetles

Article

Full-text available

Jun 2020

In this study, we focused on the direct (i.e., predation) and indirect (i.e., potential threat from coexisting with a larger individual) effects of cannibalism and intraguild predation (IGP) during larval stages of two sibling ladybird beetles. These effects play an important role in the coexistence of the generalist–common Harmonia axyridis and specialist–rare H. yedoensis (Coleoptera: Coccinellidae). Direct predation effect of cannibalism and IGP was asymmetric in the two sibling ladybird beetles; the fourth instar larvae of H . axyridis were better intraguild predators than cannibals, while the reverse was true in the larvae of H. yedoensis . Neither cannibalism nor IGP significantly affected female body weight in either species. Larval H . axyridis surviving exposure to cannibalism or IGP had a reduced number of ovarioles as adults, whereas adult H. yedoensis ovarioles were not affected. For the indirect effects, longer developmental times in males and females and a lower total number of ovarioles in females were detected in H . axyridis . In H. yedoensis , shorter developmental time of males, lighter adult weight and fewer total ovarioles in females were observed. Olfactometer choice experiments clarified that the fourth instar larvae of H . axyridis avoided the first instar conspecific larvae, while those of H. yedoensis were attracted to the odors from H . axyridis and conspecifics. Thus, H . axyridis has an avoidance mechanism only for cannibalism but not for IGP, whereas H. yedoensis does not have any avoidance mechanism. These different behaviors in the direct and indirect effects of cannibalism and IGP observed in the laboratory may play important roles in the coexistence of generalist–common H . axyridis and specialist–rare H. yedoensis in natural conditions, compensating for the large handicap of H. yedoensis at reproductive interference from H . axyridis .

The Natural Selection of Metabolism Explains Curvature in Fossil Body Mass Evolution

Article

Full-text available

Mar 2020
EVOL BIOL

Lars Witting

The natural selection of metabolism and mass can explain inter-specific body mass allometries from prokaryotes to mammals (Witting in Theor Popul Biol 117:23–42, https://doi.org/10.1016/j.tpb.2017.08.005, 2017a), with allometric exponents that depend on the selected metabolism and the packing of home ranges in predominately one (1D), two (2D), or three (3D) spatial dimensions. The predicted exponent for total metabolism for a 2D packing of home ranges increases from 3/4 to 7/4 when the fraction of the inter-specific body mass variation that follows from the natural selection of metabolism increases from zero to one. While a 3/4 exponent is commonly observed for inter-specific comparisons in mammals, a 7/4 exponent has so far not been reported. Yet, I detect the full range of exponents for evolution over time in the fossil record. There are no fossil data for allometric correlations between metabolism and mass, but I show that the allometry \( \left( {\dot{w} \propto w^{{\hat{\dot{w}}}} } \right) \) for the rate of evolution \( \left( {\dot{w} = {\text{ d }}w/{\text{ d }}t} \right) \) in mass (w) in physical time (t) is given by the underlying set of allometries for life history parameters, including mass-specific metabolism. The \(\hat{\dot{w}}\) exponent describes the curvature of body mass evolution in time, with predicted values including: 3/2 (2D) for within niche evolution in small horses over 54 million years. 5/4 (2D) and 9/8 (3D) for across niche evolution of maximum mass in four mammalian clades. 3/4 (2D) for fast evolution in large horses, and maximum mass in trunked and terrestrial mammals. And 1 for maximum mass across major lifeforms during 3.5 billion years of evolution along a metabolic bound. These results integrate the inter-specific allometries of existing species with a deeper understanding of their natural selection during evolutionary diversification over millions of years.

Social selection acts on behavior and body mass but does not contribute to the total selection differential in Eastern chipmunks

Article

Full-text available

Nov 2019

Through social interactions, phenotypes of conspecifics can affect an individual's fitness, resulting in social selection. Social selection is assumed to represent a strong and dynamic evolutionary force that can act with or in opposition to natural selection. Few studies, however, have estimated social selection and its contribution to total selection in the wild. We estimated natural and social selection gradients on exploration, docility, and body mass, and their contribution to selection differentials, in a wild Eastern chipmunk population (Tamias striatus). We applied trait‐based multiple regression models derived from classical phenotypic selection analyses, which allowed us to include several social partners (i.e., neighbors). We detected social selection gradients on female docility and male body mass, indicating that female with docile neighbors and males with large neighbors had lower fitness. In both sexes, social selection gradients varied with the season. However, we found no phenotypic assortment or disassortment for the studied traits. Social selection gradients, therefore, did not contribute to total selection differentials, and natural selection alone could drive phenotypic changes. Evaluating the factors that drive the evolution of the covariance between interacting phenotypes is necessary to understand the role of social selection as an evolutionary force. This article is protected by copyright. All rights reserved

REPRODUCTIVE BIOLOGY OF STRIPED SNAKEHEAD (Channa striata Bloch, 1973) IN BOGOR AND BEKASI, WEST JAVA

Article

Full-text available

Jan 2018

Striped snakehead is one of the potential local species, however, its production in Indonesia still comes from capture fisheries. Over exploitation had decrease the population in nature. Domestication is one of promising tool to solve the problems faced. In order to breed the domesticated species, the information of their reproduction was needed. This study aimed to describe relationship between length and weight, length and fecundity, weight – fecundity and gonad weight – fecundity of the striped snakehead from West Java. A total of 19 mature female specimens were collected from Parung (Bogor), and seven mature female specimens were collected from Babelan (Bekasi). The results showed that the determinant value (R2), the first for Parung and the second for Babelan, between weight and fecundity were 0.599 and 0.843, length-fecundity were 0.541 and 0.841; gonad weight – fecundity 1.00 and 0.846 Gonadosomatic Index (GSI) ranged from 0.67 to 9.94% and 2.03 to 8.17%. Gonad Index ranged from 6.17 – 76.73 and 18.48 – 76.77, respectively. The data indicated that growth pattern was allometric. Length and body weight has linear relationship with gonads and fecundity. Fecundity has higher correlation to the weight rather than length. Gonad weight and fecundity has a strong relationship.

A synthesis of major environmental-body size clines of the sexes within arthropod species

Article

Full-text available

Jun 2019
OECOLOGIA

Body size at maturity often varies with environmental conditions, as well as between males and females within a species [termed Sexual Size Dimorphism (SSD)]. Variation in body size clines between the sexes can determine the degree to which SSD varies across environmental gradients. We use a meta-analytic approach to investigate whether major biogeographical and temporal (intra-annually across seasons) body size clines differ systematically between the sexes in arthropods. We consider 329 intra-specific environmental gradients in adult body size across latitude, altitude and with seasonal temperature variation, representing 126 arthropod species from 16 taxonomic orders. On average, we observe greater variability in male than female body size across latitude, consistent with the hypothesis that, over evolutionary time, directional selection has acted more strongly on male than female size. In contrast, neither sex exhibits consistently greater proportional changes in body size than the other sex across altitudinal or seasonal gradients, akin to earlier findings for plastic temperature-size responses measured in the laboratory. Variation in the degree to which body size gradients differ between the sexes cannot be explained by a range of potentially influential factors, including environment type (aquatic vs. terrestrial), voltinism, mean species’ body size, degree of SSD, or gradient direction. Ultimately, if we are to make better sense of the patterns (or lack thereof) in SSD across environmental gradients, we require a more detailed understanding of the underlying selective pressures driving clines in body size. Such understanding will provide a more comprehensive hypothesis-driven approach to explaining biogeographical and temporal variation in SSD.

Ecología reproductiva de Aurivela tergolaevigata (Teiidae) en el monte del noroeste de Argentina: efectos de las variaciones ambientales interanuales

Article

Full-text available

May 2019

Gabriela A Gallardo

Reproductive ecology of Aurivela tergolaevigata (Teiidae) in nortwesthern Argentina monte: effects of interanual environmental variations. Aurivela tergolaevigata inhabits open areas of the Monte biome, and its reproductive biology is scarcely known. Due to the high rainfall interannual variability in this biome, I studied its reproductive phenology, fat body cycle and fertility during two consecutive years. The annual activity period of A. tergolaevigata goes from early spring (October) to the end of summer (March). The size at which they reach reproductive maturity was the same for males and females (LHC = 49 mm). The spermatogenic cycle was continuous, with higher activity between October and March, but most of them stop spermatogenesis concomitant with the decrease of heliophany in February. Females lay eggs during the most rainy period, prior to summer, when neonates are more abundant. The interan-nual comparison showed that longer humid conditions extend the receptivity of females and the spermatogenic cycle. Males and females storage lipids in the abdominal fat bodies by the end of the reproductive period. Females produce from one to three eggs per litter, according to body size. This study shows that A. tergolaevigata has the plasticity to extend the reproduc-tive activity if environmental conditions are favorable; this has been also observed in other phylogenetically close species

REPRODUCTIVE BIOLOGY OF STRIPED SNAKEHEAD (Channa striata Bloch, 1973) IN BOGOR AND BEKASI, WEST JAVA [Biologi Reproduksi Ikan Gabus ( Channa striata Bloch, 1973) di Bogor dan Bekasi, Jawa Barat]

Article

Full-text available

Dec 2017

Size-dependent predation and correlated life history traits alter eco-evolutionary dynamics and selection for faster individual growth

Article

Full-text available

Mar 2018

Age at maturation is a key life history trait influencing individual fitness, population age structure, and ecological interactions. We investigated the evolution of age at maturity through changes in the von Bertalanffy growth constant for organisms with a simple juvenile-adult life history. We used Gillespie eco-evolutionary models to uncover the role of predation in driving the evolution of the growth constant when eco-evolutionary dynamics are present. We incorporated both size-independent and size-dependent predation into our models to generate differences in selection and dynamics in the system. Our results generally support the idea that faster ontogenetic growth is beneficial when populations are growing but that predation tends to have little effect on age at maturity unless there are trade-offs with other life history traits. In particular, if faster ontogenetic growth comes at the cost of fecundity, our results suggest that predation selects for intermediate levels of growth and fecundity. Eco-evolutionary dynamics influenced the nature of selection only when growth was linked to fecundity. We also found that predators that increasingly consume larger prey tend to have higher population sizes due to the greater energy intake from larger prey, but the growth rate-fecundity trade-off reversed this pattern. Overall, our results suggest an important role for interactions between size-dependent foraging and life-history trade-offs in generating varying selection on age at maturity through underlying growth traits.

Demographic patterns in coral reef fishes: biogeographic trends and fishing effects

Thesis

Full-text available

Nov 2007

R. R. M. K. P. Ranatunga

The present study is a multi-scale study which investigates the demographic plasticity within and between geographically distinct reef fishes of the families Lutjanidae (Snappers), Serranidae (groupers) and Labridae (hogfish). This also investigates how fishing alters fish demography and demographic shifts associated with introduction to new habitats. These were determined by analyzing age-based demographic parameters, biological and ecological information as a basis for management and conservation. Demographic characteristics such as size, age, longevity, mortality rates and broad-scale spatial patterns in growth were described in this comparative study. Present study will provide unique contribution to general life history theory by focusing on number of species and large scale environmental gradients extending latitudinally and longitudinally across and within Caribbean, Pacific and Indian oceans. The potential shifts in demography of Lutjanus griseus (gray snapper) was examined across a geographic gradient. Samples were obtained from locations spanning from low latitude Los Roques (11°N), and Belize (17°N) to high latitude Bermuda (32°N) in the Caribbean. Results revealed substantial plasticity in demography across latitudinal gradient within and among species. Maximum longevity for L. griseus varied from 6 yr in Belize, 12 yr in Los Roques to 34 in Bermuda. Longevity showed almost 5-fold difference in Bermuda compared to its Belize counterpart. Maximum age of 34 yr determined in this study is the oldest age recorded for L. griseus, anywhere in the world. Maximum size also showed great degree of variation among location. Largest maximum size of 770 mm for L. griseus was found in Bermuda where as smallest maximum size was 440 mm in Belize. This large body size and extended lifespan of Bermuda population presumed to be latitudinal effect rather than fishing effect. Maximum longevity showed a strong negative relationship with sea surface temperature. This support the idea that there are fundamental differences in ecology, biology and population dynamics of reef fish assemblages over bio-geographic scales. Present study also investigated the age-specific growth and life-history characteristics of hogfish, Lachnolaimus maximus, a large reef fish belongs to the family Labridae (wrasses). Fishing pressure on hogfish has reduced many populations of hogfish to critically low levels and the species has identified as vulnerable to extinction and included in IUCN Red List. L. maximus examined from four geographic locations in the Caribbean subjected to varying levels of fishing pressure. Hogfish from Margarita and Belize, locations with high fishing pressure, had a smaller FL (mean FL of 239 and 278 mm, respectively). Los Roques, where the reefs are protected from fishing has the largest mean FL (459 mm). Maximum longevity observed for L. maximus was 16 yr from Bermuda and 10 yr in Los Roques. Margarita and Belize populations were relatively short-lived with the oldest fish estimated were 5 yr and 7 yr, respectively. The results also demonstrated that hogfish collected from Bermuda and Los Roques attained a larger size-at-age than those fish sampled from Belize and Margarita. Growth curves indicated that L. maximus from Belize and Margarita were slower growing compared to two other populations making them more vulnerable to exploitation. Estimates of the instantaneous rate of total mortality for hogfish showed lower values in Los Roques (0.45) and Bermuda (0.53), in contrast, intensively fished populations showed significantly higher total mortality rates [Belize (0.81) and Margarita (0.71)]. Lutjanus apodus from Belize and Los Roques, and Cephalopholis cruentatus from Belize, Los Roques, Las Aves, Curacao and Barbados, locations from the same latitude but subjected to varying levels of fishing, were studied for possible demographic signatures of fishing. Growth curves of L. apodus showed significant differences among two locations indicating different growth trajectories. Both Belize and Los Roques populations had similar growth up to 6 years and noticeable shifts in L∞ in Los Roques thereafter. 95% Confidence regions around K and L∞ showed no overlapping between Belize and Los Roques which confirmed the existence of different growth trajectories. Among L. apodus populations, mean maximum sizes achieved were higher in Los Roques compared to Belize (510 and 381 mm, respectively). Belize population of L. apodus had higher instantaneous mortality rate (0.17) compared to Los Roques (0.08). Both Belize and Los Roques locations lie within the same latitude minimizing any latitudinal effects. Therefore differential growth trajectories presumed to be associated with different exploitation rates exert on the two populations. The smaller size-at-age observed in Belize could be a result of high fishing pressure and therefore, removal of older age classes. The maximum age achieved for L. apodus in present study was 31 years from a protected reef environment (Los Roques) while maximum age recorded from a location subjected to fishing (Belize) was 24 years. Maximum longevity observed in present study for L. apodus (31 yr) is the highest recorded from anywhere in the world. It was evident that L. apodus has remarkably greater longevity than previously reported. Six populations of Graysby (Cephalopholis cruentatus) subjected to three levels of fishing, (high fishing - Belize and Curacao, moderate fishing - Las Aves and Barbados and low fishing - Los Roques) were also evaluated for their resilience to fishing. These populations were found along same latitude. Graysby population from Los Roques, where fishing is not allowed, had extended lifespan (22 yr). Populations from Las Aves and Barbados had moderate level of fishing intensity and also moderate maximum lifespan, whereas in Belize and Curacao with highest fishing intensity, therefore, highest mortality rates (0.5 and 0.6), had very short maximum lifespans (8 yr in both locations). Belize and Curacao showed no obvious asymptote although all the other populations did so. The Curacao and Belize populations exhibited a pattern of exponential decline in age distribution without marked peaks thereafter, while other populations had multi-mode age distributions. Both Belize and Curacao populations showed slow growth making them more vulnerable to intense fishing. It seems that high fishing pressure influences age structure, resulting in shorter lived fish. The demographic shift associated with introduction to new environments was investigated as the final part of this study. The Hawaiian Archipelago is known for its relatively less-represented nearshore marine fish fauna. The most striking feature is the absence of native shallow-water snappers and groupers, two most common taxa found in shallow reefs elsewhere in tropics. The blacktail snapper, Lutjanus fulvus has been introduced to Hawaii from their native habitats of Moorea and Marquesas Islands, where they become established in Hawaiian Archipelago. These introductions have implications for conservation biology because, in spite of the fact that only a few individuals transfer their characteristics to subsequent generations, no significant change in genetic diversity can be observed. As L. fulvus was introduced into the Hawaii reefs with no native snappers or groupers, it was expected that they would have a rapid growth rate compared to Moorea. However, the Marquesas is a high productivity environment due to upwelling which may result in very rapid growth. Results revealed that L. fulvus in Hawaii did not attain ages as great as none of their native populations in Marquesas or Moorea. Longest-lived L. fulvus were found from Marquesas 10 yr and Moorea (7 yr), and shortest-lived was the Hawaii population (6 yr). von Bertalanffy growth curves revealed that Hawaiian population grew faster than their native populations and attained a larger maximum size. Relative absence of competitors in Hawaii would be the reason for this larger body size and faster growth. These Pacific populations were also compared with L. fulvus from Cocos (Keeling) (Indian Ocean). The 95% confidence ellipse revealed that the demographic characteristic of Hawaiian population of L. fulvus was more similar to Cocos (Keeling) than their ancestral populations in Marquesas or Moorea. Based on the studies I conclude that there are obvious biogeographical scale patterns in demographics and the differing patterns among and within species indicate complex spatial variability in demographics. Reduced maximum size with corresponding reduction in average age and longevity may be a result of latitudinal effect or fishing effect. Exploitation influences community structure directly through preferential removal of larger-bodied fishes or indirectly as, larger-bodied fishes may exert top-down control upon other community members. Some of the species concerned shared some characteristics associated with high vulnerability to fishing, e.g. relatively slow growth and moderate to long lifespans, demography and body size. Estimates of mortality and survival rates for the selected species indicate the present status of exploited populations and also give insight on how long this fishery could be sustain under present fishing pressure. This study also provides the opportunity to examine species that have recently invaded areas from which they were naturally absent. This will contribute significantly to the knowledge of the effects of introductions into the marine tropical water and improve the basis for management of such actions.

Eco‐energetic consequences of evolutionary shifts in body size

Article

Full-text available

Nov 2017
ECOL LETT

Size imposes physiological and ecological constraints upon all organisms. Theory abounds on how energy flux covaries with body size, yet causal links are often elusive. As a more direct way to assess the role of size, we used artificial selection to evolve the phytoplankton species Dunaliella tertiolecta towards smaller and larger body sizes. Within 100 generations (c. 1 year), we generated a fourfold difference in cell volume among selected lineages. Large-selected populations produced four times the energy than small-selected populations of equivalent total biovolume, but at the cost of much higher volume-specific respiration. These differences in energy utilisation between large (more productive) and small (more energy-efficient) individuals were used to successfully predict ecological performance (r and K) across novel resource regimes. We show that body size determines the performance of a species by mediating its net energy flux, with worrying implications for current trends in size reduction and for global carbon cycles.

The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals

Article

Full-text available

Sep 2017

Lars Witting

I show that the natural selection of metabolism and mass can select for the major life-history and allometric transitions that define lifeforms from viruses, over prokaryotes and larger unicells, to multicellular animals. The proposed selection is driven by a mass-specific metabolism that is selected as the pace of the resource handling that generates net energy for self-replication. An initial selection of mass is given by a dependence of mass-specific metabolism on mass in replicators that are close to a lower size limit. A sublinear maximum dependence selects for virus-like replicators, with no intrinsic metabolism, no cell, and practically no mass. A superlinear dependence selects for prokaryote-like self-replicating cells, with asexual reproduction and incomplete metabolic pathways. These self-replicators have selection for increased net energy, and this generates a gradual unfolding of population-dynamic feed-back selection from interactive competition. The incomplete feed-back selects for larger unicells with more developed metabolic pathways, and the completely developed feed-back for multicellular animals with sexual reproduction. This model unifies the natural selection of lifeforms from viruses to multicellular animals, and it provides a parsimonious explanation where allometries and major life histories evolve from the natural selection of metabolism and mass.

The estimation of growth dynamics for Pomacea maculata from hatchling to adult

Article

Full-text available

Jul 2017

Pomacea maculata is a relatively new invasive species to the Gulf Coast region and potentially threatens local agriculture (rice) and ecosystems (aquatic vegetation). The population dynamics of P. maculata have largely been unquantified, and therefore, scientists and field-workers are ill-equipped to accurately project population sizes and the resulting impact of this species. We studied the growth of P. maculata ranging in weights from 6 to 105 g, identifying the sex of the animals when possible. Our studied population had a 4:9 male:female sex ratio. We present the findings from initial analysis of the individual growth data of males and females, from which it was apparent that females were generally larger than males and that small snails grew faster than larger snails. Since efforts to characterize the male and female growth rates from individual data do not yield statistically supported estimates, we present the estimation of several parameterized growth rate functions within a population-level mathematical model. We provide a comparison of the results using these various growth functions and discuss which best characterizes the dynamics of our observed population. We conclude that both males and females exhibit biphasic growth rates, and thus, their growth is size-dependent. Further, our results suggest that there are notable differences between males and females that are important to take into consideration in order to accurately model this species' population dynamics. Lastly, we include preliminary analyses of ongoing experiments to provide initial estimates of growth in the earliest life stages (hatchling to ≈6 g).

The effects of population density and lake characteristics on growth and size structure of brook trout Salvelinus fontinalis (Mitchill, 1815) in boreal forest lakes in Canada

Article

Jun 2017
J APPL ICHTHYOL

This paper examines the effect of lake characteristics on population density and how this variation affects growth, mortality and population size structure of brook trout, Salvelinus fontinalis. The study was conducted on 17 recreationally fished, reproductively isolated boreal forest lakes in Newfoundland, Canada from 1993 to 2000. A standardized sampling program, the Fyke Littoral Index Netting program (FLIN) was used to collected data that describes brook trout population parameters and life history attributes. Regression analyses showed significant relationships between fish density and biomass and characteristics of the lakes. Variation in fish density and biomass was explained by lake surface area and littoral habitat area. Significant relationships were found when growth, mortality and size structure were regressed against density. The proportional stock distribution and theoretical maximum size of brook trout were negatively related to density, and natural mortality was positively related to density. The largest maximum length and highest proportional stock densities occurred at brook trout densities of less than 30 fish/ha. In general, the higher the proportion of littoral habitat area the higher the densities of brook trout, which correspondingly had important effects on growth, natural mortality and size structure of the brook trout populations. This information is critical to the development of management strategies aimed at altering size distribution to produce specific fisheries management outcomes.

A model for brain life history evolution

Article

Full-text available

Mar 2017

Complex cognition and relatively large brains are distributed across various taxa, and many primarily verbal hypotheses exist to explain such diversity. Yet, mathematical approaches formalizing verbal hypotheses would help deepen the understanding of brain and cognition evolution. With this aim, we combine elements of life history and metabolic theories to formulate a metabolically explicit mathematical model for brain life history evolution. We assume that some of the brain’s energetic expense is due to production (learning) and maintenance (memory) of energy-extraction skills (or cognitive abilities, knowledge, information, etc.). We also assume that individuals use such skills to extract energy from the environment, and can allocate this energy to grow and maintain the body, including brain and reproductive tissues. The model can be used to ask what fraction of growth energy should be allocated at each age, given natural selection, to growing brain and other tissues under various biological settings. We apply the model to find uninvadable allocation strategies under a baseline setting (“me vs nature”), namely when energy-extraction challenges are environmentally determined and are overcome individually but possibly with maternal help, and use modern-human data to estimate model’s parameter values. The resulting uninvadable strategies yield predictions for brain and body mass throughout ontogeny and for the ages at maturity, adulthood, and brain growth arrest. We find that: (1) a me-vs-nature setting is enough to generate adult brain and body mass of ancient human scale and a sequence of childhood, adolescence, and adulthood stages; (2) large brains are favored by intermediately challenging environments, moderately effective skills, and metabolically expensive memory; and (3) adult skill is proportional to brain mass when metabolic costs of memory saturate the brain metabolic rate allocated to skills.

The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals

Article

Full-text available

Nov 2016

Lars Witting

I show that the natural selection of metabolism and mass is selecting for the major life history and allometric transitions that define lifeforms from viruses, over prokaryotes and larger unicells, to multicellular animals with sexual reproduction. The proposed selection is driven by a mass specific metabolism that is selected as the pace of the resource handling that generates net energy for self-replication. This implies that an initial selection of mass is given by a dependence of mass specific metabolism on mass in replicators that are close to a lower size limit. A maximum dependence that is sublinear is shown to select for virus-like replicators with no intrinsic metabolism, no cell, and practically no mass. A maximum superlinear dependence is instead selecting for prokaryote-like self-replicating cells with asexual reproduction and incomplete metabolic pathways. These self-replicating cells have selection for increased net energy, and this generates a gradual unfolding of a population dynamic feed-back selection from interactive competition. The incomplete feed-back is shown to select for larger unicells with more developed metabolic pathways, and the completely developed feed-back to select for multicellular animals with sexual reproduction. This model unifies natural selection from viruses to multicellular animals, and it provides a parsimonious explanation where allometries and major life history transitions evolve from the natural selection of metabolism and mass.

Developmental instability in German Iris flower as a potential biomonitoring method

Article

Full-text available

Jan 2016

In light of the increasing need for appropriate, cost-effective detection methods of anthropogenic pollution, we evaluated the biomonitoring potential of flower developmental instability (DI) on a widely planted decorative species, Iris germanica, under in situ conditions. DI was measured by fluctuating and radial asymmetries of parts of Iris germanica perianth (810 fall lengths and widths), from clones already growing in two distinct types of habitats with contrasting levels of anthropogenic pollution: in unpolluted (rural) areas, Novi Banovci, Stari Banovci and Belegiš (flowers from 137 clones sampled), and in a polluted (urban) Belgrade metropolitan area (flowers from 133 clones sampled). Our results revealed significantly higher flower radial asymmetry in the polluted habitats compared to unpolluted ones (for three out of four univariate indices, as well as both multivariate ones), but failed to detect a similar effect on fluctuating asymmetry indices. The results of our study therefore demonstrate the potential of DI (when estimated by flower radial asymmetry) in Iris germanica as a cost-effective biomonitoring method for in situ pollution detection based on readily measurable flower parts and moderate sample sizes.

Partner fidelity and reciprocal investments in the mating system of a simultaneous hermaphrodite

Article

Full-text available

Apr 2016

Simultaneous hermaphrodites that exchange gametes within pairs allow us to test whether equity of resource exchange is positively associated with duration of cooperative partnerships. The chalk bass (Serranus tortugarum) provides an excellent model system for such research because they spawn daily, trading sex roles with the same mating partners in repeated spawning bouts (a tactic called “egg parceling”). Even so, they live in site-attached aggregations with opportunities for extra-pair matings. We asked whether individuals spawn preferentially with 1 long-term partner and whether partner fidelity was associated with matching in the number of eggs produced in a single day by individuals within pairs. In addition, we observed random focal individuals during spawning to determine whether egg parceling was coordinated within pairs: we asked whether parcel number (per day) was well matched within pairs and whether parcels were exchanged in nonrandom sequences. We did not witness any “break-ups” in our long-term pairs; during each monthly census, all identified pairs were found spawning and courting with their “primary” mating partner until one or both of them disappeared. Daily egg production and the number of egg parcels exchanged within primary partnerships were coordinated. The sequence of parcel exchange was fairly regular, although ca. 20% of focal individuals fertilized or exchanged a few egg parcels with another partner(s); parceling allows individuals the option to exchange eggs outside of the primary pair. Our study provides novel empirical evidence of strong pair bonds and resource matching even in relatively large social groups with extra-pair trading opportunities.

The fisheries and primary productivity of the Keta Lagoon World Journal of Biological Research Revue Mondiale de la Recherche Biologique

Article

Full-text available

Jan 2014

The Keta Lagoon in Ghana supports artisanal fisheries which comprise significant proportion of economic and dietary resources of the people. The state of the fisheries and primary productivity of the Keta Lagoon based on the two sites, Anloga and Woe, were studied from August, 2010 to March, 2011. A total of 22 finfish species belonging to 12 genera and 10 families were encountered in the Keta Lagoon. Fish species diversity based on Shannon-Wiener's index (Hˈ), Species Richness based on Margalef's index (D) and Species Evenness based on Pielou's index (J) were generally low at both Anloga site at 1.27, 1.07 and 0.19, respectively and Woe site at 1.84, 1.75 and 0.25, respectively. The length-weight regression coefficient (b) indicated that Tilapia zillii (3.12) and Tilapia guineensis (2.90) from Anloga sampling site as well as Sarotherodon melanotheron (2.66), Tilapia zillii (3.03), Tilapia guineensis (2.92) and Gerres melanopterus (3.13) from Woe sampling site grow isometrically. The condition factor (K) indicated that the fish species from Anloga site were in better condition than those from Woe. The Trophic Status Index based on Chlorophyll a estimation indicated that the lagoon was hypereutrophic. The high primary productivity was attributable to the high concentration levels of nutrients especially nitrate (95.31 mgl-1 , 79.44 mgl-1) and phosphate (0.007 mgl-1 , 0.005 mgl-1) for Anloga and Woe sites respectively contributed from farmlands situated around the lagoon through leaching. This was evident in decreased dissolved oxygen levels. Chloride levels were however at concentrations lethal to most of the fish species.

Numerical taxonomy of two new mite species of the genus Caloglyphus Berlese (Acaridae) from Pakistan

Article

Full-text available

Sep 2005
Pakistan J Sci Ind Res

During the mite sampling of the genus Caloglyphus, the taxonomical analysis of diagnostic features of the hypopial stage confirmed two new taxa named as C. agrios and C. hadros. When compared with the already known worldwide species within this genus, these species showed sufficient dissimilarity to be classified as separate taxa. The characteristic features differentiating these new species from the other Caloglyphus species are the shapes of gnathosoma, propodosoma, hysterosoma, apodemes, coxal fields, suctorial shield, and chaetotaxy and solenidiotaxy of legs. The present study reports the historical review of the genus, completed with the information on already known species, their description, illustration of main characters, geographical distribution, host range, remarks on the new species, matrixes showing comparisons, and the percentage of similarity along with a key for their identification based on hypopial characters for the species known from Pakistan.

An analysis of life-history invariants in Eurasian perch, Perca fluviatilis

Article

Full-text available

Jan 2006
EVOL ECOL RES

Questions: Can life-history traits be aggregated into dimensionless and invariant indices? Can meaningful inferences be derived from such invariants? Can important life-history traits be predicted from simple measures of growth and mortality rates? Organism: A medium-sized freshwater fish with a complex life history, Eurasian perch (Perca fluviatilis). Perch often display one of two growth types: slow growing and small-sized (stunted), or rapid growing and large-sized (often piscivorous). Data used: Literature data from 75 populations spanning the natural distribution range of perch in Eurasia. Conclusions: Most life-history traits are related through trade-offs, and covary in a predictable manner among populations. Suggested life-history invariants could be deemed as invariant using standard criteria. However, an observed difference between growth types suggests that evolutionary inference from invariants should be drawn with caution. On the other hand, simple optimality models based on information about growth and mortality schedules do predict age and size at maturity and reproductive investment with reasonably high precision.

Effects of Water Pollution in Koluama Area, Niger Delta Area, Nigeria Fish Species Composition, Histology, Shrimp Fishery and Fishing Gear Type

Article

Jun 2013

The effect of water pollution in Koluama Area in the Niger Delta region of Nigeria to determine its effects on fish species composition, histology, shrimp fishery and fishing gear type. A total of twenty (20) species belonging to eleven (11) families were recorded. Strongylura senegalensis, Lagocephalus laevigatus, Tarpon atlantica, Pristis pristis, Galeoides decadatylus and Butis koilomatodon were rare. Ephippion guttifer, Chaetodipterus goreensis, Sardinella maderensis, Sardinella aurita, Liza falcipinnis, Mugil bananensis, Pentanemus quinquarius, Polydactylus quadrafilis and Trichuris lepturis were common. Ethmalosa fimbriata, Liza grandisquamis, Sphyraena guachancho, Mugil curema, Sphyraena guachancho and Dormitator pleurops were abundant. None was dominant. The highest number of fish species (16) were recorded in fish town and none was recorded in Kuloma 1 and one (1) was recorded for Kulauma 11. Foroupa, Ekeni, Ejetu and Ikebiri fishing port 1 and 2 recorded 8, 7, 3 and 5 fish species respectively. Artisanal fishing is based on traditional methods of fishing using essentially canoe and different fishing nets which depend on the season and target fish species. Canoes may be motorized or hand-paddled. Common gear types include shrimp traps, drift gill nets, set gill nets, cast nets, seine nets, hook and lines. Lift nets may be use by women folk who target small shrimp species in the creeks and creek lets. Other fishing methods include hand-picking for periwinkles, oysters and other shellfish by women folk and children. Prominent among the fishing devices are edek, a type of fish fence used in the creeks; alot, a large trap used on sand and mud-banks in the estuaries; and otunwa, a barbed spear. Fishers using these devices either operated from their home villages, exploiting the nearby waters, or staged long distance fishing expeditions, during which they lived in distant camps or house-boats. The heavy metals concentration level values are: Cd (0.013a±0.001), Cr (2.04b±0.01), Cu (2.16b±0.10), Pb (2.20b±0.16) and Zn (1.03ab±0.03) for Lagocephalus laevigatus; Cd (0.01a±0.001), Cr (1.60b±0.44), Cu (1.25ab±0.08), Pb (1.10ab±0.15) and Zn (0.50b±0.04) for Tarpon atlantica and Cd (0.02ab±0.003), Cr (2.35ab±0.40), Cu (2.60a±0.08), Pb (2.30a±0.45) and Zn (1.11a±0.17) for Pristis pristis. The presence of heavy metals in the fish samples examined is an evidence of environmental degradation.

How fast is fast? Eco-evolutionary dynamics and rates of change in populations and phenotypes

Article

Full-text available

Nov 2015

It is increasingly recognized that evolution may occur in ecological time. It is not clear, however, how fast evolution – or phenotypic change more generally – may be in comparison with the associated ecology, or whether systems with fast ecological dynamics generally have relatively fast rates of phenotypic change. We developed a new dataset on standardized rates of change in population size and phenotypic traits for a wide range of species and taxonomic groups. We show that rates of change in phenotypes are generally no more than 2/3, and on average about 1/4, the concurrent rates of change in population size. There was no relationship between rates of population change and rates of phenotypic change across systems. We also found that the variance of both phenotypic and ecological rates increased with the mean across studies following a power law with an exponent of two, while temporal variation in phenotypic rates was lower than in ecological rates. Our results are consistent with the view that ecology and evolution may occur at similar time scales, but clarify that only rarely do populations change as fast in traits as they do in abundance.

Relative contributions of evolutionary and ecological dynamics to body size and life-history changes of herring (Clupea harengus) in the Bothnian Sea

Article

Full-text available

Jul 2014
EVOL ECOL RES

Question: What ecological and evolutionary processes are associated with the 25% decrease in age-specific body size of herring (Clupea harengus) in the Bothnian Sea over the last 30 years? Data: Four decades of data on length, age, and sexual maturity of individual herrings as well as environmental variables, including abundances of predators, prey and competitors, and estimates of fishing intensity/mortality from the Bothnian Sea. Search methods: Information-theoretic assessment of the relative influence of ecological and fisheries' effects on temporal changes in body growth. Probabilistic maturation reaction norms to study changes in age-specific size at maturation. Decomposition of trait variation into ecological and evolutionary contributions. Conclusions: Our evolutionary ecosystem perspective shows that both ecological and evolutionary processes are important contributors to observed phenotypic changes in this commercially exploited species. Around 60% of the decrease in age-specific body length can be attributed to increased density-dependent body growth. Evolutionary changes towards earlier maturation, owing to an indirect effect of size-selective mortality from grey seals and fisheries, account for a further 25% of the decrease in age-specific body size.

Article

Full-text available

Jan 2003
ZOOL STUD

Influence of male and female body size on mating preference in Phorticella striata is studied with the help of male and female choice experiments. In female preferential mating (female choice), males with long wings were observed to be successful mating with both large and small females, indicating the success of large over small males in male rivalry, which may also be due to selection by females. In male preferential mating (male choice) both large and small males preferred mating with large females. These results prove that size-assortative mating exists in the drosophilid P. striata. Courtship latency, mating latency, copulation duration, fecundity, and fertility were studied using 4 different crosses (large male x large female; large male x small female; small male x large female; small male x small female). Courtship latency and mating latency were shorter for crosses in which 1 or both sexes were large. In the small male x small female cross the longest courtship and mating latencies were observed. Lower fecundity was noticed in the cross small male x large female cross, and differences in fecundity with the other 3 crosses were statistically insignificant. The large male x large female cross showed the highest fertility, and differences between the other 3 crosses were statistically insignificant. Correlations among longer copulation duration, higher fecundity, and the highest fertility exist only for the cross involving both sexes of the large size. This reveals that higher fertility depends on both duration of copulation and body size of both sexes involved. The number of ovarioles present in larger and smaller Phorticella was studied. As body size increases, the ovariole number also increases. In the light of results obtained in Phorticella striata, the authors support the hypothesis of‘bigger the better’proposed by Hegde and Krishna (1997).

The interplay between resource supply and demand determines the influence of predation on prey body size

Article

Full-text available

Jun 2015

Predation has been shown to either increase or decrease the body mass of fish, as well as cause variable changes in growth rate. The mechanisms underlying these contrasting responses are not well understood. Here we compared intraspecific body size and growth responses to predation against a backdrop of 2006 estimates of asymptotic mass and growth constants (i.e., von Bertalanffy parameters) across species. We show that intra specific responses can be quite large relative to inter specific variation and confirm that the magnitude and direction of body size responses is variable. We then employed the supply-demand (SD) model of body mass evolution to explore how predator-induced changes in resource demand or supply could alter body mass. The SD model predicts that any combination of increasing or decreasing body mass and increasing or decreasing growth rate is possible when predation risk is increased, which is consistent with the literature. Finally, we use three case studies to illustrate how the interplay of resource supply and resource demand determines the actual body mass and growth rate response to predation.

The influence of metabolic rate, temperature and sex on life history parameters.

Article

Jan 1993

Wayne A Van Voorhies

Smaller Australian raptors have greater urban tolerance

Article

Full-text available

Jul 2023

Urbanisation is occurring around the world at a rapid rate and is generally associated with negative impacts on biodiversity at local, regional, and global scales. Examining the behavioural response profiles of wildlife to urbanisation helps differentiate between species that do or do not show adaptive responses to changing landscapes and hence are more or less likely to persist in such environments. Species-specific responses to urbanisation are poorly understood in the Southern Hemisphere compared to the Northern Hemisphere, where most of the published literature is focussed. This is also true for raptors, despite their high diversity and comparably high conservation concern in the Southern Hemisphere, and their critical role within ecosystems as bioindicators of environmental health. Here, we explore this knowledge gap using community science data sourced from eBird to investigate the urban tolerance of 24 Australian raptor species at a continental scale. We integrated eBird data with a global continuous measure of urbanisation, artificial light at night (ALAN), to derive an urban tolerance index, ranking species from positive to negative responses according to their tolerance of urban environments. We then gathered trait data from the published literature to assess whether certain traits (body mass, nest substrate, habitat type, feeding guild, and migratory status) were associated with urban tolerance. Body size was negatively associated with urban tolerance, as smaller raptors had greater urban tolerance than larger raptors. Out of the 24 species analysed, 13 species showed tolerance profiles for urban environments (positive response), and 11 species showed avoidance profiles for urban environments (negative response). The results of this study provide impetus to conserve native habitat and improve urban conditions for larger-bodied raptor species to conserve Australian raptor diversity in an increasingly urbanised world.

A theory of fertility and parental investment in traditional and modern human societies

Article

Jan 1996
AM J PHYS ANTHROPOL

Hillard Kaplan

Demographic consequences of changing body size in a terrestrial salamander

Article

Full-text available

Dec 2020

Changes in climate can alter individual body size, and the resulting shifts in reproduction and survival are expected to impact population dynamics and viability. However, appropriate methods to account for size‐dependent demographic changes are needed, especially in understudied yet threatened groups such as amphibians. We investigated individual‐ and population‐level demographic effects of changes in body size for a terrestrial salamander using capture–mark–recapture data. For our analysis, we implemented an integral projection model parameterized with capture–recapture likelihood estimates from a Bayesian framework. Our study combines survival and growth data from a single dataset to quantify the influence of size on survival while including different sources of uncertainty around these parameters, demonstrating how selective forces can be studied in populations with limited data and incomplete recaptures. We found a strong dependency of the population growth rate on changes in individual size, mediated by potential changes in selection on mean body size and on maximum body size. Our approach of simultaneous parameter estimation can be extended across taxa to identify eco‐evolutionary mechanisms acting on size‐specific vital rates, and thus shaping population dynamics and viability.

Detecting the Signature of Body Mass Evolution in the Broad-Scale Architecture of Food Webs

Article

Jun 2020

John P Delong

Body mass-based links between predator and prey are fundamental to the architecture of food webs. These links determine who eats whom across trophic levels and strongly influence the population abundance, flow of energy, and stability properties of natural communities. Body mass links scale up to create predator-prey mass relationships across species, but the origin of these relationships is unclear. Here I show that predator-prey mass relationships are consistent with the idea that body mass evolves to maximize a dependable supply of resource uptake. I used a global database of ~2,100 predator-prey links and a mechanistic optimization model to correctly predict the slope of the predator-prey mass scaling relationships across species generally and for nine taxonomic subsets. The model also predicted cross-group variation in the heights of the body mass relationships, providing an integrated explanation for mass relationships and their variation across taxa. The results suggest that natural selection on body mass at the local scale is detectable in ecological organization at the macro scale.

Length-weight relationship and condition factor of Sphyraena afra from the coastal waters of Lagos State

Article

Full-text available

Mar 2019

The length-weight relationship and condition factor of Sphyraena afra from the Lagos coast (LC) and the Lagos lagoon complex (LLC) in the coastal waters of Lagos State were studied for a period of two years. Parameters a and b of the length-weight relationship were estimated using the equation W = a x TL b , while the condition factor was calculated with the equation K = 100 x BW x TL ⁻³ . The relationships of fish condition factor and body length, sex, and seasons in Lagos coastal waters were determined. The species exhibited negative allometric growth (b < 3, P < 0.05) for males, females, and combined sexes with the length exponent (b) ranging from 2.72 to 2.85. Correlation coefficient r ranged from 0.89 to 0.98. The allometric growth values obtained in LC and LLC from the length-weight relationship indicated that the fish species exhibited increases in length rather than in weight. The overall mean condition factors (K) for S. afra from the LC and the LLC were 0.97 ± 0.11 and 1.17 ± 0.12, respectively. The mean condition factors of females were higher than those for males at most of the sampling stations, and S. afra was observed to be in better condition during the dry season.

ECTOTHERMS FOLLOW THE CONVERSE TO BERGMANN'S RULE

Article

Full-text available

Apr 1997
EVOLUTION

Timothy A Mousseau

QUANTITATIVE GENETIC AND OPTIMALITY ANALYSES OF LIFE-HISTORY PLASTICITY IN THE EASTERN MOSQUITOFISH, GAMBUSIA HOLBROOKI

Article

Jun 1996
EVOLUTION

Adaptive phenotypic plasticity in growth, development, and body size in the yellow dung fly

Article

Oct 1998
EVOLUTION

Wolf U Blanckenhorn

Life-history theory predicts that age and size at maturity of organisms should be influenced by time and food constraints on development. This study investigated phenotypic plasticity in growth, development, body size, and diapause in the yellow dung fly, Scathophaga stercoraria. Full-sib families were allowed to develop under predator-free field conditions. The time before the onset of winter was varied and each brood was split into three environments differing in the amount of dung a set number of larvae had as a resource. When resources were abundant and competition was minimal, individuals of both sexes grew to larger body sizes, took longer time to mature, and were able to increase their growth rates to attain large body sizes despite shorter effective development periods later in the season. In contrast, limited larval resources and strong competition constrained individuals to mature earlier at a smaller adult size, and growth rates could not be increased but were at least maintained. This outcome is predicted by only two life-history optimality models, which treat mortality due to long development periods and mortality due to fast growth as independent. Elevated preadult mortality indicated physiological costs of fast growth independent of predation. When larval resources were limited, mortality increased with heritable variation in development time for males, and toward the end of the season mortality increased as larval resources became more abundant because this induced longer development periods. Sexual and fecundity selection favoring large body size in this species is thus opposed by larval viability selection favoring slower growth in general and shorter development periods when time and resources are limited; this overall combination of selective pressures is presumably shaping the reaction norms obtained here. Flexible growth rates are facilitated by low genetic correlations between development time and body size, a possible consequence of selection for plasticity. Heritable variation was evident in all traits investigated, as well as in phenotypic plasticity of these traits (genotype X interactions). This is possibly maintained by unpredictable spatiotemporal variation in dung abundance, competition, and hence selection.

ADAPTATION TO SEASONALITY IN A CRICKET: PATTERNS OF PHENOTYPIC AND GENOTYPIC VARIATION IN BODY SIZE AND DIAPAUSE EXPRESSION ALONG A CLINE IN SEASON LENGTH

Article

Full-text available

Nov 1989
EVOLUTION

This paper investigates patterns of phenotypic variation in the striped ground cricket (Allonemobious fasciatus) along a cline in season length and tests the hypothesis that variation in body size and diapause propensity is the result of diversifying selection due to different local conditions. We examined 83 populations and found that A. fasciatus produced a single generation per year (univoltine) north of 37°N latitude and was bivoltine south of 35°30'N. Body size generally increased with increasing season length, with a sudden drop in the region corresponding to the transition from univoltine to bivoltine life cycles, reflecting the division of total season length in two within-bivoltine populations. We reared ten populations in our laboratory and found that much of the interpopulation variance in body size observed in the field could be attributed to genetic differences. Diapause expression also varied significantly among populations and was strongly correlated with season length. The heritability of body size did not differ between populations, but full-sib estimates greatly exceeded parent-offspring estimates (h po2=0.15±0.05; h fs2=0.45±0.04) suggesting that there are important nonadditive genetic effects. The heritability of diapause expression, determined from analysis of full sibs, varied significantly between populations (0.33 ± 0.10 to 1.31 ± 0.21) with an average of 0.74 ± 0.16. Body size and diapause expression were genetically correlated in transition-zone populations, but not in univoltine or bivoltine populations. Our findings support the suggestion that clinal variation in body size and diapause expression in the striped ground cricket reflect adaptation to season length.

Introduction Dynamics of Size-Structured Populations: An Overview

Chapter

Jan 1988

The size range of organisms is enormous, spanning over 21 orders of magnitude, with the blue whale and giant sequoia being 1021 heavier than the smallest microbe (McMahon and Bonner 1983). An organism is often identified as an individual in a given developmental stage, usually as a full-grown adult, which is, in many cases, a questionable point of view. As J. T. Bonner (1965) has argued, the ultimate description of an individual includes the whole life cycle. In many organisms the individuals pass through a wide spectrum of sizes, spanning more than four orders of magnitude, during the independent part of their life cycles; well-known examples are plants, fishes and reptiles. Thus, also within a species, individuals often vary greatly in size. Such large variation in size will have profound evolutionary and population dynamic consequences, which is the topic of this book.

Effects of Body Size and Reproductive State on Cover Use of Five Species of Temperate-Zone Natricine Snakes

Article

Jan 2016

An animal's decision to stay in a protective refuge or venture from it will depend on the exigencies of other necessary functions (e.g., feeding, breeding, thermoregulation), which often will interact themselves. In this study, we determined broad patterns of use of cover objects in five species of diurnal natricine snakes at two locations in Canada and one location in the UK. In particular, we focused on the influence of body size (larger snakes should incur less risk away from cover) and reproductive state (gravid snakes thermoregulate precisely and therefore should often bask) on the probability that a snake will be found in the open. As we predicted, body size influenced the likelihood of being in the open, both within and between species (one small species was almost always found under cover), even when we took time of day, season, or both into account. Such relationships are unlikely to be solely caused by the thermoregulatory role of cover, and we argue that small snakes sometimes sacrifice basking opportunities to take advantage of the protective qualities of cover. However, small snakes might use cover to avoid dehydration as well as predators. As we also predicted, gravid females were more likely to be in the open at a given body size than other snakes, but only in the three largest viviparous species the smallest species and one oviparous species showed no such effect. In general, body size and reproductive state both determine cover-use behavior. Studies of use of other kinds of cover or refuges by snakes (e.g., vegetation, underground burrows), and of time spent under cover vs. in the open, would help test the generality of our conclusions.

The basic life history parameters and their relationships

Article

Full-text available

Jan 2004
ZH OBSHCH BIOL

We consider an ideal population with a stable age composition changing according Lotka equation. Additional assumptions are made concerning the constancy of population size, independence of specific mortality rate on age, and linear dependence of female fecundity on its weight. A relationship has been obtained N[α, ω]/n0 = 1/scl 0w̄[α, ω]-1, where N 0 is initial numbers of a generation, N[α, ω] is total numbers of the mature part of the population, w̄ [α, ω] is a mean weight of a mature individual, s is sex ratio, c is specific fecundity (per unit of weight) and l0 is the probability of larval surviving. The growth of an individual is described by the Bertalanffy function. Methods of calculation of life history parameters are discussed. A method is proposed to calculate the age of maturity (α) and at the end (ω) of the reproduction period as first and second inflection points of the growth rate curve. Based upon data on development of 27 populations of several species of fishes of inland waters of Russia the following relationships have been obtained: N[α, ω]/ n0 = 0.087w̄[α, ω]0.087 for populations with w̄[α,ω] ≤ 100 g, N [α, ω]/n0 = 0.037w̄ [α, ω]0.278 for populations with w̄[α, ω] > 100 g, and N [α, ω]/n0 = 0.063w̄ [α, ω]0.189 for all populations.

Interspecific differences in growth of somatic and reproductive tissues during the breeding season in Menidia menidia and M. beryllina

Article

Aug 1999
J FISH BIOL

The annual atherinid fishes, Menidia menidia and M. beryllina, are extremely similar morphologically, but appear to differ in their energetics and life histories. They emerge from winter in relatively emaciated condition. Menidia menidia males and females showed little change in carcass weight but significant increases in gonad weight in March and April prior to spawning in May. Female liver weight increased in March and remained high. Thus, this species had reached its reproductive size in the autumn and allocated its energy to gonadal growth during the spring. Menidia beryllina showed no significant increases in weight until early May, when carcass, liver and gonad all increased simultaneously, a pattern very different from its congener. The later spawning of M. beryllina is probably due both to its need for carcass growth in spring prior to spawning and to its apparent requirement for warmer water for growth. Females of both species invested more into liver and gonad than did males. Maximum gonadosomatic index was about twice as large for M. menidia males as for M. beryllina males, but the index was similar for females of both species.

Adaptive Significance of Large Size and Long Life of the Chaetognath Sagitta Elegans in the Arctic

Article

Full-text available

Sep 1966

Ian Mclaren

Zooplankton of high latitudes generally develop more slowly, reach a large size, and live longer than related forms in warmer seas. Existing explanations are reviewed and a new one offered. Where generation length is set by marked seasonality of food supply, as in the arctic, high fecundity and associated large size and slow development may be selected for. It is shown from analysis of generation length, fecundity, and natural mortality of the chaetognath Sagitta elegans than its biennial life cycle in the eastern Canacian Arctic is of optimal length.

An Allocation Model of Growth and Reproduction in Fish

Article

Full-text available

Sep 1983

Derek Roff

A simple model is proposed to describe the pattern of allocation of resources into growth and reproduction. This model assumes that there is a fixed amount of surplus energy which may be channeled into either somatic or gonadal tissue. The change in weight or length of a fish can be predicted from this model from the surplus energy and the gonadosomatic index. In many species the gonadosomatic index can be assumed to be a constant. Surplus energy can be estimated by inverting the growth equations. It is thereby possible to examine the consequences on Darwinian fitness of changes in the age at maturity or the allocation to reproduction as measured by changes in the gonadosomatic index. The allocation model is validated using data on growth of American plaice Hippoglossoides platessoides. The reproductive strategy of American plaice cannot be accounted for on the basis of the trade-off between growth and reproduction.-from Author

Dwarfing or stunting in the genus Tilapia (Cichlidae) a possibly unique recruitment mechanism

Article

Jan 1973

T.D. Iles

The Evolution of Life History Parameters in Teleosts

Article

Jun 1984

Derek Roff

Empirical studies have shown that in teleosts there is a significant correlation between the life history parameters, age at first reproduction, natural mortality, and growth rate. In this paper 1 hypothesize that these correlations are the result of evolutionary adjustments due to the trade-off between reproduction, growth, and survival. A simple and reasonable assumption is that the costs of reproduction are sufficient to cause the l t m t function to decrease. A simple expression relating the age at first reproduction is derived from this assumption. This formula accounts for a statistically significant portion (60.6%) of the variation in age at first reproduction in 30 stocks of fish. To extend the model to predict the distribution of life history parameters across all teleosts, an explicit cost function is incorporated. The model is analyzed with respect to two fitness measures, the expected lifetime fecundity and malthusian parameter, r. In the first case it is shown that the optimal age at maturity, T, depends only on the natural mortality rate (M) and the growth rate (k). In the second case, T is a function of k and the logarithm of a parameter, In C; the latter is a product of egg and larval survival, maximum body length (L x ), and the proportionality coefficient of the fecundity/length function. Difficulties of measuring egg and larval survival make the testing of the latter case difficult for particular species. However, this method provides a simple formula for the computation of r; this is shown generally to be approximately zero, thereby adding strength to the assumptions of the first analysis. The distribution patterns of T on k and M on k are predicted and compared with the observed pattern. In general, the predictions are validated: however, certain combinations of k and ln C are shown to occur very infrequently. The prediction of such "empty" regions of the parameter space remains a challenge for future development of life history theory.

Evolution In Age-Structured Populations

Article

Sep 1983

Populations of many species, including man, are age-structured: the individuals present in the population at any one time were born over a range of different times, and their fertility and probability of future survival depend on age. Aspects of age-structured populations discussed include demography and ecological dynamics; the theory of natural and artificial selection; and the genetic effects of finite population size. Chapters are: models of age-structured populations; genetics of populations without selection; selection - construction of a model and the properties of equilibrium populations; selection - dynamic aspects; the evolution of life-histories.- P.J.Jarvis

On Being the Right Size

Article

Sep 1981

Derek Roff

Most examinations of body size center on a single factor. However, because body size is directly or indirectly linked to many, if not most, life history characters a more holistic approach is advocated. In this paper I present such an approach in the analysis of the optimum body size of Drosophila melanogaster. The basic life history parameters determining r are shown to be related to body size. Using these functions the relationship between r and body size is obtained. It is found that r is maximized within the observed range in size. A sensitivity analysis indicates that this result does not depend critically upon parameter estimation. This analysis also indicates that variation in egg size between geographic strains should be positively correlated to variation in body size. This prediction is shown to be correct. Reasonable variation in parameter values can account for much of the size range observed in the genus Drosophila. It does not appear to be possible to account for the very large size of certai...

Development Rates and the Optimal Body Size in Drosophila: A Reply to Ricklefs

Article

Oct 1983

Derek Roff

The Genetic Factor in Population Ecology

Article

Jan 1960

L. C. Birch

The genetic plasticity of populations implies that the numbers of animals, which is what the population ecologist studies, may be a reflection of change in genetic composition either in space or in time. Alternatively the number of animals may itself be a cause of genetic change. These genetic aspects of ecology will be more important when genetic plasticity is more characteristic than phenotypic plasticity. In relation to changing environment genetic plasticity can only be adaptive when the length of the generation is less than the time the environment takes to change. Both types of plasticity exist throughout the animal and plant kingdoms. In some groups of animals in which phenotypic plasticity is common, as in fishes, it is extremely difficult to establish the extent to which genetic plasticity exists. Adaptation through genetic plasticity depends upon a continuous source of genetic variability. The source is mutation and in addition, in sexual organisms, recombination of genes. Sex also introduces th...

Yellow Perch (Perca flavescens) Biomass Responses to Different Levels of Phytoplankton and Benthic Biomass in Lake Memphremagog, Quebec–Vermont

Article

Apr 2011

Perch biomass in Lake Memphremagog, Quebec was 2.5 times greater in the more productive south than in the less productive north basins. This difference is on the same order of magnitude as biomass differences in the phytoplankton (approximately 1.6×) and benthic (approximately 3×) communities. The difference in perch biomass is attributed to a larger perch population in the south basin. Growth was similar in both basins, and therefore independent of production at these lower trophic levels. Perch growth in both basins is maximal for the Quebec area and probably controlled by the length of the growing season. Abundance levels are fixed by the fourth year and possibly prior to reaching the second year of life. Perch biomass responses to different food levels in Lake Memphremagog provide empirical support to Moore’s (1941) suggestion that at abundant food levels, population size and not growth is enhanced. Previous experiments defining the relation between growth and nutrient concentration and/or primary production did not fully represent the situation in Lake Memphremagog. This may have been due to conditions in simple, controlled systems not usually found in natural, complex ones.

The Costs of Reproduction and Their Consequences

Article

Jul 1980

Graham Bell

On the Interrelationships between Natural Mortality, Growth Parameters, and Mean Environmental Temperature in 175 Fish Stocks

Article

Dec 1980

Daniel Pauly

A compilation of values for the exponential coefficient of natural mortality (M) is given for 175 different stocks of fish distributed in 84 species, both freshwater and marine, and ranging from polar to tropical waters. Values of L∞(LT, cm), W∞(g, fresh weight), K (1/year) and T (°C, mean annual water temperature) were attributed to each value of M, and the 175 sets of values plotted such that: 1) log M = −0·2107 − 0·0824 log W ∞ + 0·6757 log K + 0·4627 log T and 2) log M = −0·0066 − 0·279 log L ∞ + 0·6543 log K + 0·4634 log T The multiple correlation coefficients are for 1) 0·845, and for 2) 0·847, while the critical value (171 d.f.) is 0·275 (for P = 0·01). All slopes are significantly ≠ 0 (for P = 0·001). The standard deviation of estimates of log M are for 1) 0·247, and for 2) 0·245. The equations provide highly reliable estimates of M for any given fish stock, given the values of W ∞ or L ∞ and K of the von Bertalanffy growth formula, and an estimate of the mean water temperature in which the stock in question lives. Only two groups have values of M generally differing from those obtained through the proposed equations: the Clupeidae, with generally lower and the polar fishes with generally higher values. Correction factors are given for both groups. Potential applications of the findings to population dynamics are discussed together with some ecological implications.

The Genetical Theory of Natural Selection

Article

Jan 1930

Ronald Aylmer Fisher

Comparative fish population studies [microform] /

Article

I-Hsun Ni

Vita. Thesis (Ph. D.)--University of British Columbia, 1978. Includes bibliographical references (leaves 137-179). Microfiche of typescript.

Minimum Size of Mammalian Homeotherms: Role of the Thermal Environment

Article

Jan 1978

Richard Tracy

The minimum size of a mammalian homeotherm appears to be related to the animal's maximum rate of endogenous heat production, the ambient thermal environment, and the animal's ability to be a facultative homeotherm.

Studies on natural populations of Drosophila. V. Correlated response to selection in Drosophila melanogaster

Article

Feb 1966

IN the series of experiments to be described, a population of Drosophila melano- gaster was selected for increase or decrease in wing length, with and without inbreeding, and the resulting changes in thorax length, rate of egg production, and longevity were observed. Heritabilities, and phenotypic and genetic correla- tions were also measured at intervals during the ten generations of selection. The aim was to add to our knowledge of the effects of such selection both on another metric character and on characters believed to be related to the populations's "fitness"-i.e., egg production, percentage of emergence and longevity.

Studies on Natural Populations of Drosophila. IX. Some Fitness Components and Their Heritabilities in Natural and Mutant Populations of DROSOPHILA MELANOGASTER

Article

Feb 1970

The growth of yellow perch in various Quebec waters

Jan 1973
165-176

J Grimaldi
G Leduc

Grimaldi, J., and G. Leduc. 1973. The growth of yellow perch in various Quebec waters. Nat. Can. 100: 165-176.

Selection for colonizing ability. Pages 77-94 in

Jan 1965

R C Lewontin

Lewontin, R. C. 1965. Selection for colonizing ability. Pages 77-94 in H. G. Baker and G. L. Stebbins, eds. The Genetics of Colonizing Species. Academic Press, New York.

LewontinSelection for colonizing ability77The Genetics of Colonizing Species1965

R C Lewontin

Reproductive strategies in flatfish: a first synthesis

Jan 1982
CAN J FISH AQUAT SCI
1686-1698

_ _. 1982. Reproductive strategies in flatfish: a first synthesis. Can. J. Fish. Aquat. Sci. 39: 1686-1698.

Energy cost of egg production and environmental determinants of fecundity in teleost fishes

Jan 1979
13-159

R J Wooton

Wooton, R. J. 1979. Energy cost of egg production and environmental determinants of fecundity in teleost fishes. Symp. Zool. Soc. Lond.44: 13-159.

Predicting Body Size with Life History Models

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