Michael D Jennions

Michael D Jennions
Australian National University | ANU · Research School of Biology (RSB)

DPhil (Oxford)

About

291
Publications
66,511
Reads
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21,622
Citations
Additional affiliations
September 2001 - present
Australian National University
Position
  • Professor (Full)
October 1994 - February 1996
University of Oxford
Position
  • PhD Student

Publications

Publications (291)
Preprint
Full-text available
Several hundred butterfly species show some form of migratory behaviour. Here we identify how the methodologies available for studying butterfly migration have changed over time, and document geographic and taxonomic foci in the study of butterfly migration. We review publications on butterfly migration published in six languages [English, Simplifi...
Article
Destruction of natural habitats for tree plantations is a major threat to wildlife. These novel environments elicit behavioural changes that can either be detrimental or beneficial to survival and reproduction, with population – and community – level consequences. However, compared with well-documented changes following other forms of habitat modif...
Article
Paternal age and past mating effort by males are often confounded, which can affect our understanding of a father's age effects. To our knowledge, only a few studies have standardized mating history when testing for effects of paternal age, and none has simultaneously disentangled how paternal age and mating history might jointly influence offsprin...
Article
Full-text available
In many animal species, males may exhibit one of several discrete, alternative ways of obtaining fertilisations, known as alternative reproductive tactics (ARTs). Males exhibiting ARTs typically differ in the extent to which they invest in traits that improve their mating success, or the extent to which they face sperm competition. This has led to...
Article
The notion that men are more variable than women has become embedded into scientific thinking. For mental traits like personality, greater male variability has been partly attributed to biology, underpinned by claims that there is generally greater variation among males than females in non-human animals due to stronger sexual selection on males. Ho...
Article
Many studies ask whether young or older males are better at acquiring mates. Even so, how age affects reproductive success is still poorly understood because male age and mating history are confounded in most studies: older males usually have more mating experience. To what extent does mating history rather than age explain variation in male mating...
Preprint
The outcomes of fights often affect the fitness of males by determining their access to mates. ‘Winner-loser’ effects, where winners often win their next contest, but losers tend to lose, can therefore influence how males allocate resources towards traits under pre- and post-copulatory sexual selection. We experimentally manipulated the winning/los...
Article
Older males often perform poorly under post-copulatory sexual selection. It is unclear, however, whether reproductive senescence is because of male age itself or the accumulated costs of the higher lifetime mating effort that is usually associated with male age. To date, very few studies have accounted for mating history and sperm storage when test...
Article
Full-text available
Akin to handedness in humans, some animals show a preference for moving to the left or right. This is often attributed to lateralised cognitive functions and eye dominance, which, in turn, influences their behaviour. In fishes, behavioural lateralisation has been tested using detour mazes for over 20 years. Studies report that certain individuals a...
Preprint
Older males often perform poorly under post-copulatory sexual selection. It is unclear, however, whether reproductive senescence is due to male age itself or the accumulated costs of the higher lifetime mating effort that is usually associated with male age. To date, very few studies have accounted for male mating history when testing for the effec...
Article
Full-text available
Although it is widely stated that both mating behavior and sperm traits are energetically costly for males, we currently lack empirical estimates of the relative costs to males of pre‐ versus postcopulatory investments. Such estimates require the experimental separation of the act of mating from that of ejaculation, which is a nontrivial logistical...
Article
Maternal effects are an important evolutionary force that may either facilitate adaptation to a new environment or buffer against unfavourable conditions. The degree of variation in traits expressed by siblings from different mothers is often sensitive to environmental conditions. This could generate a Maternal-by-Environment interaction (M × E) th...
Article
Temperature experienced during early development can affect a range of adult life‐history traits. Animals often show seemingly adaptive developmental plasticity—with animals reared at certain temperatures performing better as adults at those temperatures. The extent to which this type of adaptive response occurs in gonadal tissue that affects sperm...
Article
Full-text available
As cities continue to grow it is increasingly important to understand the long-term responses of wildlife to urban environments. There have been increased efforts to determine whether urbanization imposes chronic stress on wild animals, but empirical evidence is mixed. Here, we conduct a meta-analysis to test whether there is, on average, a detrime...
Article
Full-text available
Should females prefer older males as mates? Male survival to old age might indicate the presence of fitness-enhancing genes that increase offspring fitness. However, many correlational studies show that mating with older males can lower female fecundity and even reduce offspring fitness due to epigenetic or germline mutation effects. One problem in...
Article
The evolution of male genital traits is usually ascribed to advantages that arise when there is sperm competition, cryptic female choice or sexual conflict. However, when male-female contact is brief and sperm production is costly, genital structures that ensure the appropriate timing of sperm release should also be under intense selection. Few stu...
Article
Full-text available
In many species, males exhibit phenotypic plasticity in sexually selected traits when exposed to social cues about the intensity of sexual competition. To date, however, few studies have tested how this plasticity affects male reproductive success. We initially tested whether male mosquitofish, Gambusia holbrooki (Poeciliidae), change their investm...
Article
Studies often show that paternal age affects offspring fitness. However, such effects could be due either to age, or to a male's previous mating effort (which is necessarily confounded with age). We experimentally tested whether differences in the mating history of old males affect offspring performance in the mosquitofish Gambusia holbrooki. Upon...
Preprint
Full-text available
Stressful conditions, like novel host environment, can stimulate mothers to produce offspring with phenotypes that better suit the conditions they are likely to experience (i.e. adaptive maternal effects). However, mothers might vary in their ability to adjust their offspring's phenotype in response to environmental cues. This could generate a mate...
Article
Full-text available
Changes in mate availability and sperm competition should generate selection to adjust investments into different pre- and post-copulatory traits so that the product of mating and fertilization success maximize net male reproductive success. Given costly sperm production and the risk of sperm depletion, males should invest strategically in ejaculat...
Article
Many studies quantify how polyandry affects female fitness by allowing females to either mate with one or several males. But even if the number of matings is standardized, such studies conflate any costs of interacting with males with the potential benefits of receiving sperm from several males, obscuring the benefits of polyandry. We conducted a 2...
Article
Most sexually selected traits are costly to produce and therefore tend to show condition-dependent expression. But individuals have a finite set of resources to invest across the multiple traits on which sexual selection acts. This necessarily leads to trade-offs among individual traits and between different reproductive stages. The effect of male...
Preprint
Full-text available
How to define and use the concept of inclusive fitness is a contentious topic in evolutionary theory. Inclusive fitness can be used to calculate selection on a focal gene, but it is also applied to whole organisms. Individuals are then predicted to appear designed as if to maximise their inclusive fitness, provided that certain conditions are met (...
Article
Full-text available
Natural selection operates via fitness components like mating success, fecundity and longevity, which can be understood as intermediaries in the causal process linking traits to fitness. Sexual selection occurs when traits influence mating or fertilisation success, which, in turn, influences fitness. We show how to quantify both these steps in a si...
Article
Full-text available
Parental effects on offspring performance have been attributed to many factors such as parental age, size, and condition. However, we know little about how these different parental characteristics interact to determine parental effects, or the extent to which their effect on offspring depends on either the sex of the parent or that of the offspring...
Article
Winning or losing a fight can have lasting effects on competitors. Controlling for inherent fighting ability and other factors, a history of winning often makes individuals more likely to win future contests, while the opposite is true for losers (the 'winner-loser effect'). But does the winner-loser effect also influence a male's mating success? W...
Article
The costs of mating for a female might depend on both her phenotype and that of her mate. Sexually antagonistic male traits that negatively affect females are often condition dependent, so a male's rearing environment can affect the costs he imposes on his mate. Likewise, a female's ability to resist male-imposed costs might be condition dependent....
Article
Full-text available
Males often produce dynamic, repetitive courtship displays that can be demanding to perform and might advertise male quality to females. A key feature of demanding displays is that they can change in intensity: escalating as a male increases his signalling effort, but de-escalating as a signaller becomes fatigued. Here, we investigated whether fema...
Article
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The impact of environmental conditions on the expression of genetic variance and on maternal effects variance remains an important question in evolutionary quantitative genetics. We investigate here the effects of early environment on variation in seven adult life history, morphological, and secondary sexual traits (including sperm characteristics)...
Article
Full-text available
The term ‘sex roles’ encapsulates male–female differences in mate searching, competitive traits that increase mating/fertilization opportunities, choosiness about mates and parental care. Theoretical models suggest that biased sex ratios drive the evolution of sex roles. To model sex role evolution, it is essential to note that in most sexually rep...
Article
Full-text available
Spatial and temporal variation in environmental factors and the social setting can help to maintain genetic variation in sexually selected traits if it affects the strength of directional selection. A key social parameter which affects the intensity of, and sometimes predicts the response to, mating competition is the operational sex ratio (OSR; ra...
Article
Jennions et al. introduce the different kinds of sex ratio and their biology.
Article
Full-text available
Mating with relatives has often been shown to negatively affect offspring fitness (‘inbreeding depression’). There is considerable evidence for inbreeding depression due to effects on naturally selected traits, particularly those expressed early in life, but there is less evidence of it for sexually selected traits. This is surprising because sexua...
Article
Full-text available
Chemical communication in aquatic species can affect many key life history traits, such as prey and predator detection and mate searching. However, changes in the environment can disrupt the effectiveness of signals and the ability of individuals to detect these signals. Many studies have examined the effect of secondary compounds from exotic plant...
Article
Full-text available
Selection can favor phenotypic plasticity in mate choice in response to environmental factors that alter the costs and benefits of being choosy, or of choosing specific mates. Human-induced environmental change could alter sexual selection by affecting the costs of mate choice, or by impairing the ability of individuals to identify preferred mates....
Article
Full-text available
Courting males often perform different behavioural displays that demonstrate aspects of their quality. Male fiddler crabs, Uca sp., are well known for their repetitive claw-waving display during courtship. However, in some species, males produce an additional signal by rapidly stridulating their claw, creating a ‘drumming’ vibrational signal throug...
Data
ESM 1. The in-field sprint track set up at East Point Reserve, Darwin, Northern Territory, Australia
Chapter
Full-text available
This article is online only. The authors do not have pdf copies. https://link.springer.com/referenceworkentry/10.1007/978-3-319-16999-6_1941-1
Article
Full-text available
(1)The detrimental effects of matings between relatives are well known. However, few studies determine the extent to which inbreeding depression in males is due to natural or sexual selection. Importantly, measuring fitness or key fitness components, rather than phenotypic traits allows more accurate estimation of inbreeding depression. (2)We inves...
Article
Full-text available
Inbreeding is often associated with a decrease in offspring fitness (‘inbreeding depression’). Moreover, it is generally assumed that the negative effects of inbreeding are exacerbated in stressful environments. This G × E interaction has been explored in many taxa under different environmental conditions. These studies usually manipulate environme...
Article
Non-genetic inheritance (NGI) is the transmission of parental factors, other than DNA sequences, to offspring that then affect their phenotype. Within the last decade, NGI has invoked considerable interest from evolutionary biologists. Numerous models indicate that NGI could be an important contributor to processes driven by natural selection, incl...
Article
Full-text available
Background Challenging conditions experienced early in life, such as a restricted diet, can detrimentally affect key life-history traits. Individuals can reduce these costs by delaying their sexual maturation, albeit at the price of the later onset of breeding, to eventually reach the same adult size as individuals that grow up in a benevolent envi...
Article
Full-text available
Male harassment is a classic example of how sexual conflict over mating leads to sex-specific behavioural adaptations. Females often suffer significant costs from males attempting forced copulations, and the sexes can be in an arms race over male coercion. Yet, despite recent recognition that divergent sex-specific interests in reproduction can aff...
Article
Male harassment is a classic example of how sexual conflict over mating leads to sex-specific behavioural adaptations. Females often suffer significant costs from males attempting forced copulations, and the sexes can be in an arms race over male coercion. Yet, despite recent recognition that divergent sex-specific interests in reproduction can aff...
Article
In many birds males are presumed to protect their paternity by closely guarding their mate or copulating frequently with her. Both these costly behaviours are assumed to reduce the risk and/or intensity of sperm competition. However, despite many studies on avian extra-pair paternity, it remains unclear how strongly these behaviours are related to...
Article
Full-text available
Sex-role evolution theory attempts to explain the origin and direction of male-female differences. A fundamental question is why anisogamy, the difference in gamete size that defines the sexes, has repeatedly led to large differences in subsequent parental care. Here we construct models to confirm predictions that individuals benefit less from cari...
Article
Morrissey (2016) is an enjoyable but challenging read that highlights misapplication of meta-analysis to questions in evolutionary biology. The problems highlighted in the three case studies all arise when estimating the mean magnitude rather than mean value of a relationship (i.e. using absolute rather than signed effect sizes). A statistical mave...
Article
Full-text available
Background The optimal allocation of resources to sexual signals and other life history traits is usually dependent on an individual’s condition, while variation in the expression of sexual traits across environments depends on the combined effects of local adaptation, mean condition, and phenotypic responses to environment-specific cues that affec...
Article
Full-text available
Male genitalia often show remarkable differences among related species in size, shape and complexity. Across poeciliid fishes, the elongated fin (gonopodium) that males use to inseminate females ranges from 18 to 53% of body length. Relative genital size therefore varies greatly among species. In contrast, there is often tight within-species allome...
Data
Male standard length and gonopodium length for all males measured for generation 10 (after one round of relaxed selection) for all 9 lines.
Data
File (csv format) to run along with tsp file (Supplementary Data 12) in the provided R script (Supplementary Data 13) to obtain male body shape data for all males measured for all 9 lines.
Data
File (csv format) to run along with tsp file (Supplementary Data 8) in the provided R script (Supplementary Data 9) to obtain female body shape data for all females measured for all 9 lines.
Data
Tsp file to run using R script (Supplementary Data 9) to obtain female body shape data for all females measured for all 9 lines.
Data
R script to run to obtain female body shape data for all females measured for all 9 lines
Data
File (csv format) to run along with tsp file (Supplementary Data 12) in the provided R script (Supplementary Data 13) to obtain male body shape data for all males measured for all 9 lines.
Data
Tsp file to run using R script (Supplementary Data 13) to obtain male body shape data for all males measured for all 9 lines.
Data
R script to run to obtain male body shape data for all males measured for all 9 lines
Data
Male standard length and gonopodium length for all males measured for generations 1 to 9 for all 9 lines.
Data
Total female association times with males or an empty 'control' container. Female association times with the Up, Down and Control line males. Data is for all females tested for all 9 lines.
Data
File (csv format) to run along with tsp file (Supplementary Data 16) in the provided R script (Supplementary Data 17) to obtain male gonopodium tip shape for all males measured for all 9 lines.
Data
Tsp file to run using R script (Supplementary Data 17) to obtain male gonopodium tip shape for all males measured for all 9 lines.
Data
Calculation of realized heritability of residual gonopodium length for Up- and Down-selected lines in replicates A, B and C based on LS regressions.
Data
Supplementary Figures 1-9, Supplementary Tables 1-5, Supplementary Methods and Supplementary References
Data
Male and female burst swimming performance for all individuals measured for all 9 lines.
Data
Male reproductive success for all males in all 30 test pools.
Data
File (csv format) to run along with tsp file (Supplementary Data 12) in the provided R script (Supplementary Data 13) to obtain male body shape data for all males measured for all 9 lines.
Data
File (csv format) to run along with tsp file (Supplementary Data 16) in the provided R script (Supplementary Data 17) to obtain male gonopodium tip shape for all males measured for all 9 lines.
Data
R script to run to obtain male gonopodium tip shape for all males measured for all 9 lines.