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The meaning of r- an K-selection

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This paper catalogues several different dichotomies that have all been termed r- and K-selection. The status of the concept of r- and K-selection is discussed and a more restricted usage of the terms is recommended.
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... In summary, the remarkable strategy of post-fire active functional types is to switch from a typical nutrient-stress-tolerating (Grime 1977) or a K strategy (McArthur and Wilson 1967;Parry 1981) between fires, to an opportunistic ruderal (Grime 1977) or r strategy (McArthur and Wilson 1967;Parry 1981) immediately after a fire, nomenclature depending on which ecological theory is adopted. We are aware of minor shifts in strategy during plant ontogeny (Dayrell et al. 2018), but know virtually nothing about what underpins major shifts in strategy following a wildfire. ...
... In summary, the remarkable strategy of post-fire active functional types is to switch from a typical nutrient-stress-tolerating (Grime 1977) or a K strategy (McArthur and Wilson 1967;Parry 1981) between fires, to an opportunistic ruderal (Grime 1977) or r strategy (McArthur and Wilson 1967;Parry 1981) immediately after a fire, nomenclature depending on which ecological theory is adopted. We are aware of minor shifts in strategy during plant ontogeny (Dayrell et al. 2018), but know virtually nothing about what underpins major shifts in strategy following a wildfire. ...
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Background Unveiling the diversity of plant strategies to acquire and use phosphorus (P) is crucial to understand factors promoting their coexistence in hyperdiverse P-impoverished communities within fire-prone landscapes such as in cerrado (South America), fynbos (South Africa) and kwongan (Australia). Scope We explore the diversity of P-acquisition strategies, highlighting one that has received little attention: acquisition of P following fires that temporarily enrich soil with P. This strategy is expressed by fire ephemerals as well as fast-resprouting perennial shrubs. A plant’s leaf manganese concentration ([Mn]) provides significant clues on P-acquisition strategies. High leaf [Mn] indicates carboxylate-releasing P-acquisition strategies, but other exudates may play the same role as carboxylates in P acquisition. Intermediate leaf [Mn] suggests facilitation of P acquisition by P-mobilising neighbours, through release of carboxylates or functionally similar compounds. Very low leaf [Mn] indicates that carboxylates play no immediate role in P acquisition. Release of phosphatases also represents a P-mining strategy, mobilising organic P. Some species may express multiple strategies, depending on time since germination or since fire, or on position in the landscape. In severely P-impoverished landscapes, photosynthetic P-use efficiency converges among species. Efficient species exhibit rapid rates of photosynthesis at low leaf P concentrations. A high P-remobilisation efficiency from senescing organs is another way to use P efficiently, as is extended longevity of plant organs. Conclusions Many P-acquisition strategies coexist in P-impoverished landscapes, but P-use strategies tend to converge. Common strategies of which we know little are those expressed by ephemeral or perennial species that are the first to respond after a fire. We surmise that carboxylate-releasing P-mobilising strategies are far more widespread than envisaged so far, and likely expressed by species that accumulate metals, exemplified by Mn, metalloids, such as selenium, fluorine, in the form of fluoroacetate, or silicon. Some carboxylate-releasing strategies are likely important to consider when restoring sites in biodiverse regions as well as in cropping systems on P-impoverished or strongly P-sorbing soils, because some species may only be able to establish themselves next to neighbours that mobilise P.
... In the present study, the r-selected decapods were represented by the Penaeoidea group (Dendrobranchiata). The K-selected ones were represented by the Pleocyemata, i.e., Caridea, Brachyura, Astacidae, and Achelata (Parry 1981;Fenwick 1984). The mean GS values of all groups within Dendrobranchiata and Pleocyemata were closely related, despite a little lower value for Dendrobrachiata, and exceeded the caridean shrimps that present a mean GS larger than that of the other groups (Table 2). ...
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Genome size (GS) or DNA nuclear content is considered a useful index for making inferences about evolutionary models and life history in animals, including taxonomic, biogeographical, and ecological scenarios. However, patterns of GS variation and their causes in crustaceans are still poorly understood. This study aimed to describe the GS of five Neotropical Synalpheus nongambarelloides shrimps (S. apioceros, S. minus, S. brevicarpus, S. fritzmueller, and S. scaphoceris) and compare the C-values of all Caridea Infraorder in terms of geography and phylogenetics. All animals were sampled in the coast of São Paulo State, Brazil and GS was assessed by flow cytometry analysis (FCA). The C-values ranged from 7.89 pg in S. apioceros to 12.24 pg in S. scaphoceris. Caridean shrimps had higher GS than other Decapoda crustaceans. The results reveal a tendency of obtaining larger genomes in species with direct development in Synalpheus shrimps. In addition, a tendency of positive biogeographical (latitudinal) correlation with Caridea Infraorder was also observed. This study provides remarkable and new protocol for FCA (using gating strategy for the analysis), which led to the discovery of new information regarding GS of caridean shrimps, especially for Neotropical Synalpheus, which represents the second-largest group in the Caridea Infraorder.
... To implement the ABC methodology, we remark that even if our knowledge on the value of κ is very poor, we usually have some information about an effective upper bound for κ, denoted K max , from the dynamics of the population that we model via the CBP. An example of this situation is the family of K-selected species (see [17]), which includes larger mammals such as elephants, horses, and primates, and whose species are relatively stable populations and produce relatively low numbers of offspring. For practical purposes and without loss of generality, throughout this paper we consider offspring laws with finite support. ...
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Our purpose is to estimate the posterior distribution of the parameters of interest for controlled branching processes (CBPs) without prior knowledge of the maximum number of offspring that an individual can give birth to and without explicit likelihood calculations. We consider that only the population sizes at each generation and at least the number of progenitors of the last generation are observed, but the number of offspring produced by any individual at any generation is unknown. The proposed approach is twofold. Firstly, to estimate the maximum progeny per individual we make use of an approximate Bayesian computation (ABC) algorithm for model choice and based on sequential importance sampling with the raw data. Secondly, given such an estimate and taking advantage of the simulated values of the previous stage, we approximate the posterior distribution of the main parameters of a CBP by applying the rejection ABC algorithm with an appropriate summary statistic and a post-processing adjustment. The accuracy of the proposed method is illustrated by means of simulated examples developed with the statistical software R. Moreover, we apply the methodology to two real datasets describing populations with logistic growth. To this end, different population growth models based on CBPs are proposed for the first time.
... for representative taxa within each of the classes (see Methods in Supporting Information 1 The general structure of the exemplary AES closely mirrors seminal ideas on fundamental life-history strategies (i.e. r-and Kstrategies; Parry, 1981;Pianka, 1970;Stearns, 1976Stearns, , 1977 as well as the principal trade-offs between growth, survival and reproduction that have been proposed to structure plant and animal life histories according to the dynamic energy budget theory and pace-of-life syndromes (Capdevila et al., 2020;Healy et al., 2019). ...
Article
The framework of the plant economics spectrum advanced our understanding of plant ecology and proved as a unifying concept across plant taxonomy, growth forms and biomes. Similar approaches for animals mostly focus on linking life‐history and metabolic theory, but not on their application in ecosystem research. To fill this gap, we propose the animal economics spectrum (AES) based on broadly available traits that describe organismal size, biological times and rates. To exemplify the feasibility and general usefulness of constructing the AES, we compiled data on adult and offspring body mass, life span, age at first reproduction, reproductive and metabolic rate of 98 terrestrial taxa from seven selected animal classes and mapped these taxa into an exemplary quantitative trait space. The AES consists of two principal axes related to reproductive strategies and the pace of life; both axes are linked by animal metabolism. The AES thus closely mirrors seminal ideas on fundamental life‐history strategies and more recent discoveries and developments in the fields of life‐history and metabolic theory. Furthermore, we find associations between the positions of animals within the AES and taxonomy, thermoregulation and body plan. The AES shows that key dimensions describing different ecological strategies of animals can be depicted with functional traits that are relatively easily accessible for a broad spectrum of animal taxa. We suggest future steps towards an application of the AES in ecosystem research aiming at the understanding of ecological processes and ecosystem functions. Additionally, we urge for databases that compile comparable functional traits for a large proportion of animals but also for further groups of organisms with the ultimate goal to map the economics spectrum of life. The framework of the AES will be relevant for understanding ecological processes across animal taxa at species, community and ecosystem level. We further discuss how it can facilitate predictions on how the functional composition and diversity of animal communities can be affected by global change.
... The very high fecundity of G. decadactylus in Gabonese waters resembles that found in Nigeria, where it ranged from 58 001 to 279 277 oocytes per female (mean 168 639 oocytes per female; Emmanuel et al. 2010). Very high fecundity associated with an early first size at maturity identifies G. decadactylus as an r-strategist (Pianka 1970;Nichols et al. 1976;Parry 1981). As may be expected, fecundity is strongly related to gonad size and body size in G. decadactylus. ...
Article
The lesser African threadfin Galeoides decadactylus (family Polynemidae) is one of the most captured marine fish species in Central Africa. This study examines aspects of the reproductive biology of G. decadactylus in the Libreville area of Gabon. Fish caught with encircling gillnets and bottom gillnets were collected from May 2017 to May 2018 from artisanal fishermen. A total of 776 specimens were studied, comprising 401 females (14-36 cm total length [TL]), 347 males (13-28 cm TL), and 28 individuals of indeterminate sex (12-16 cm TL). Monthly monitoring of gonadosomatic ratio, condition factor and sexual maturity stages revealed that G. decadactylus reproduces continuously but has two slight peak periods: one in the long rainy season and the other in the short rainy season. The species is protandrous, with sizes at first sexual maturity of 17.7 cm TL for males and 18.7 cm for females. Mature individuals largely dominated the catches of small-scale fishers in Gabon. Mean absolute fecundity of females was 179 447 (SD 107 240) oocytes, and mean relative fecundity was 848 (SD 323) oocytes g-1. This study provides fisheries managers with crucial knowledge, such as size at sexual maturity, that could be used as a basis for sustainable management of G. decadactylus stocks in Gabon using minimum size limits.
... r-selected species tend to have faster growth rates and are relatively short-lived. Albeit a simplified view of natural selection (Stearns, 1977;Parry, 1981), one should be able to quantify the effects of density-dependent selection on the reproductive strategies of species in an r/K continuum (Mueller et al., 1991;Reznick et al., 2002). ...
Article
Environmental stability can have profound impacts on life history trait evolution in organisms, especially with respect to development and reproduction. In theory, free-living species, when subjected to relatively stable and predictable conditions over many generations, should evolve narrow niche breadths and become more specialised. In parasitic organisms, this level of specialisation is reflected by their host specificity. Here, we tested how host specificity impacts the reproductive strategies of parasites, a subject seldomly addressed for this group. Through an extensive review of the literature, we collated a worldwide dataset to predict, through Bayesian multilevel modelling, the effect of host specificity on the reproductive strategies of parasitic copepods of fishes or corals. We found that copepods of fishes with low host specificity (generalists) invest more into reproductive output with larger clutch sizes, whereas generalist copepods of corals invest less into reproductive output with smaller clutch sizes. The differences in host turnover rates through an evolutionary timescale could explain the contrasting strategies across species observed here, which should still favour the odds of parasites encountering and infecting a host. Ultimately, the differences found in this study reflect the unique evolutionary history that parasites share both intrinsically and extrinsically with their hosts.
... Reproductive strategy assists in the colonisation of new environments and habitats. R strategist species focus primarily on the production of large amounts of juveniles, fast growth and so are able to colonise newly available habitat faster and proliferate in abundance compared to K strategist species (Parry, 1981). Furthermore, ascidians, which often colonise hard substrates, are hermaphroditic and predominantly reproduce through sexual cross-fertilisation and the production of free-swimming larvae (Rius et al., 2010). ...
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Large extents of shellfish reefs have become degraded around the world as a result of anthropogenic activities to the point where such reefs are functionally extinct in some regions. Due to the ecosystem services provided by these biogenic habitats, there has recently been a concerted effort to restore shellfish reefs, particularly in Australia. While oysters have traditionally been used as a candidate species, the Mediterranean Mussel Mytilus galloprovincialis is gaining popularity and provides a similar suite of ecosystem services to oysters. As part of a pilot program, shellfish habitats, each comprising translocated M. galloprovincialis seeded onto 100 wooden stakes, were deployed at three sites in Melville Water in the Swan-Canning Estuary (Western Australia). The aims of this study where to; 1) investigate the mortality, body condition and growth of the translocated M. galloprovincialis; 2) compare the characteristics of fish fauna at the shellfish reef habitats and nearby unstructured (control) habitats and 3) determine the benthic macroinvertebrate and tunicate species associated with the shellfish habitat. The mortality of M. galloprovincialis was high at all three sites. This was attributed to poor environmental conditions in offshore waters of Melville Water, compounded by stress associated with translocation, their spawning activity, and fouling by ascidians. Seasonally adjusted von Bertalanffy growth models best explained the growth of M. galloprovincialis and growth was rapid, with individuals attaining ~50 mm within their first year. This is likely due to the high phytoplankton availability in the Swan-Canning Estuary. The shellfish habitats harboured a significantly different fish faunal composition compared to nearby unstructured habitats (sandy areas), with many species observed only at shellfish sites or in greater densities. The increased abundances of zoobenthivores on the shellfish habitats suggest they are utilising the invertebrate prey communities associated with the structure as a food source. The invertebrate iv community varied spatially among the three sites and over time. A suite of non-native ascidians rapidly colonised the stakes along with the mussels, which, in turn, supported many small crustaceans. Given the importance of shellfish restoration globally, and the aim to undertake large-scale projects to provide such habitats in south-western Australian estuaries, the results of this study will increase the understanding of the biology of M. galloprovincialis and help elucidate how faunal communities respond and utilise shellfish habitats. The results of this pilot study will assist in the planning of future mussel reef restoration projects, in particularly those under development in southern Australia.
... Under more competitive and population dense conditions, K-selection is said to occur. Subsequent focus was on how these reproductive strategies coalesce with other differences (e.g., length of lifespan, litter size, rate of maturation) to form broad LH strategies that can be used to describe wide-ranging differences between species (Biro & Stamps, 2008;Parry, 1981;Pianka, 1970;Promislow & Harvey, 1990). K-selected, in contrast to r-selected, species mature later, have a longer lifespan, have smaller litters, and exhibit greater parental investment. ...
Article
Previous work on individual and group differences in life history (LH) strategy posited a central role for intelligence. Yet, empirical results failed to support the hypothesized positive association between a slow LH strategy and intelligence. The current investigation (N = 102) represents an attempt to not only re-examine the LH/intelligence hypothesis, but also to conduct an in-depth examination on how LH strategy and intelligence are expressed in personality profiles. The California Adult Q-sort measure of slow LH strategy exhibited a significant positive correlation with performance (r = 0.32), verbal (r = 0.34), and full (r = 0.38) IQ test scores. Additional findings suggest that a slow LH strategy and intelligence both include personality characteristics reflecting ambition and, possibly, social perceptiveness. Alternatively, intelligence is more closely aligned with a personality profile including intellectual ability, independence, and creativity while LH strategy was uniquely associated with interpersonal warmth, conformity, and reticence.
... McArthur and Wilson (1967) coined the terms r strategy and K strategy to describe selection for rapid population growth in uncrowded populations and selection for competitive ability in crowded populations, respectively. Over time, the meaning of these terms has broadened (Parry, 1981) and, according to the broader concept, B. sessilis is an r strategist, while B. attenuata is a K strategist. We do not know the physiological pattern of allocating P among foliar P fractions that allows species to exhibit a particular life history strategy and efficient use of P in contrasting low-P environments. ...
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Background and aims: Phosphorus (P) and nitrogen (N) are essential nutrients that frequently limit primary productivity in terrestrial ecosystems. Efficient use of these nutrients is important for plants growing in nutrient-poor environments. Plants generally reduce foliar P concentration in response to low soil P availability. We aimed to assess ecophysiological mechanisms and adaptive strategies for efficient use of P in Banksia attenuata (Proteaceae), naturally occurring on deep sand, and B. sessilis, occurring on shallow sand over laterite or limestone, by comparing allocation of P among foliar P fractions. Methods: We carried out pot experiments with slow-growing B. attenuata, which resprouts after fire, and faster-growing opportunistic B. sessilis, which is killed by fire, on substrates with different P availability using a randomised complete block design. We measured leaf P and N concentrations, photosynthesis, leaf mass per area, relative growth rate, and P allocated to major biochemical fractions in B. attenuata and B. sessilis. Key results: The two species had similarly low foliar total P concentrations, but distinct patterns of P allocation to P-containing fractions. The foliar total N concentration of B. sessilis was greater than that of B. attenuata on all substrates. The foliar total P and N concentrations in both species decreased with decreasing P availability. The relative growth rate of both species was positively correlated with concentrations of both foliar nucleic acid P and total N, but there was no correlation with other P fractions. Faster-growing B. sessilis allocated more P to nucleic acids than B. attenuata did, but other fractions were similar. Conclusions: The nutrient-allocation patterns in faster-growing opportunistic B. sessilis and slower-growing B. attenuata revealed different strategies in response to soil P availability which matched their contrasting growth strategy.
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The genus Gasterophilus (Diptera, Gastrophilidae) is an obligate parasite of the equine family that causes widespread myiasis in desert steppe. Based on four common naturally excreted Gasterophilus larvae collected systematically in the Karamaili Ungulate Nature Reserve from March to September 2021, this paper studies the population dynamics and ontogenetic laws of horse flies, and discuss the coexistence pattern and population dynamics prediction of horse flies. The results showed that the Gasterophilus larvae had obvious concentrated development period, and the time of population peaks was different, the earliest was G. nigricornis (late March), followed by G. pecorum-Ⅰ (mid-April), G. nasalis (late April), G. intestinalis (early May), G. pecorum-Ⅱ (mid-August). The order of development threshold temperature "Cnigricornis < Cpecorum-Ⅰ ≤ Cpecorum-Ⅱ < Cnasalis < Cintestinalis" is consistent with the peak order of different larval populations. The life history survival rate (L) was as follows: Lnigricornis (83.97%) ≥ Lintestinalis (81.25%) > Lnasalis (72.42%) ≥ Lpecorum-Ⅱ (71.65%) > Lpecorum-Ⅰ (39.23%). This study combined indoor experiments and field surveys revealed the development of horse fly populations with different life strategies in desert grasslands. Based on the different development threshold temperatures of several horse flies, the staggered population dynamics of Gasterophilus form continuous infection stress on the host. In addition, G. pecorum exhibited a univoltine bimodal population distribution in this area and led to two high-intensity host infections, which is one of the important reasons why it has become the dominant species of myiasis in desert steppe.
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It is possible to think of organisms as having a certain limited amount of time or energy available for expenditure, and of natural selection as that force which oper- ates in the allocation of this time or energy in a way which maximizes the contribution of a genotype to following generations. This manner of treatment of problems con- cerning the adaptation of phenotypes is called the "Principle of Allocation" (Levins and MacArthur, unpublished), and one of its applications might be the formulation of a general theory to account for clutch size in birds. At this stage we will assume that clutch size is a hereditary phenotypic characteristic which can be affected to a greater or lesser extent by the prevailing environmental conditions and which ex- hibits the normal variability of such char- acteristics. Lack (1954) discusses the validity of several hypotheses which' at- tempt to account for clutch size and its variation under different circumstances and conditions, all of which were rejected in favor of his now widely accepted theory that clutch size is adapted to a limited food supply. This paper is an attempt to show that this and other existing hypotheses when taken singly are inadequate in some respect to account for all the data, that each holds for some particular set of con- ditions, and that each is but a part of the complete explanation. The theories will be dealt with individually and it will be shown that as environment varies so will the fac- tors which determine clutch size. PRESENTATION OF THE THEORY
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This book had its origin when, about five years ago, an ecologist (MacArthur) and a taxonomist and zoogeographer (Wilson) began a dialogue about common interests in biogeography. The ideas and the language of the two specialties seemed initially so different as to cast doubt on the usefulness of the endeavor. But we had faith in the ultimate unity of population biology, and this book is the result. Now we both call ourselves biogeographers and are unable to see any real distinction between biogeography and ecology.