Maria Servedio | University of North Carolina at Chapel Hill (original) (raw)
Papers by Maria Servedio
PLOS Biology, Oct 2, 2023
Cold Spring Harbor Perspectives in Biology, Jan 7, 2024
Evolution, Jan 3, 2022
The strength of mate choice (choosiness) often varies with age, but theory to understand this var... more The strength of mate choice (choosiness) often varies with age, but theory to understand this variation is scarce. Additionally, theory has investigated the evolution of choosiness in speciation scenarios but has ignored that most organisms have overlapping generations. We investigate whether speciation can result in variation of choosiness with age, and whether such variation can in turn affect speciation. We develop a population‐genetic model of the evolution of choosiness in organisms with overlapping generations in the context of secondary contact between two divergent populations. We assume that females choose males that match their phenotype, such that choosiness evolves by sexual selection. We demonstrate that speciation can result in the evolution of age‐specific choosiness when the mating trait is under divergent ecological selection and age is not used as a mating cue. The cause of this result is that allele frequencies differ between choosy females and males. However, we find that the evolution of age‐specific choosiness does not affect the overall level of reproductive isolation compared to a case without age‐structure, supporting previous speciation theory. Overall, our results connect life history and speciation theory, and the mechanisms that we highlight have implications for the understanding of the role of sex‐specific selection in the evolution of choosiness.
Carolina Digital Repository (University of North Carolina at Chapel Hill), 2011
Evolution, Aug 12, 2014
Male ejaculates include large amounts of seminal fluid proteins (Sfps) that influence male sperm ... more Male ejaculates include large amounts of seminal fluid proteins (Sfps) that influence male sperm competitive success. In spite of their diverse proximate functions, Sfps involved in sperm competition increase male fitness in one of three ways: (1) "avoidance" proteins help males avoid sperm competition, (2) "defense" proteins help males defend their sperm from displacement by the female's subsequent mate, and (3) "offense" proteins aid males in displacing sperm of preceding males. Here, we present a population genetic model of the evolution of allocation of finite resources by males to the three kinds of Sfps. We analyze the influence of relative efficiencies of different Sfps, of plasticity in resource allocation, and of differences in viability costs of Sfps. We find that in absence of plasticity or different viability costs, equal investment in defense and offense Sfps evolves, irrespective of their relative efficiency. In all cases, males evolve to invest more in avoidance when avoidance proteins are increasingly efficient, and when offense is more efficient than defense. Differences in viability costs result in lower investment in costly proteins, whereas plasticity has complex effects, influencing both the optimal seminal fluid composition and maintenance of variation in investment in these proteins across populations.
bioRxiv (Cold Spring Harbor Laboratory), Mar 14, 2023
Evolution, Feb 9, 2023
Sexual selection has a rich history of mathematical models that consider why preferences favor on... more Sexual selection has a rich history of mathematical models that consider why preferences favor one trait phenotype over another (for population genetic models) or what specific trait value is preferred (for quantitative genetic models). Less common is exploration of the evolution of choosiness or preference strength: i.e., by how much a trait is preferred. We examine both population and quantitative genetic models of the evolution of preferences, specifically developing “baseline models” of the evolution of preference strength during the Fisher process. Using a population genetic approach, we find selection for stronger and stronger preferences when trait variation is maintained by mutation. However, this force is quite weak and likely to be swamped by drift in moderately-sized populations. In a quantitative genetic model, unimodal preferences will generally not evolve to be increasingly strong without bounds when male traits are under stabilizing viability selection, but evolve to extreme values when viability selection is directional. Our results highlight that different shapes of fitness and preference functions lead to qualitatively different trajectories for preference strength evolution ranging from no evolution to extreme evolution of preference strength.
Ecology and Evolution, Mar 6, 2018
Journal of Evolutionary Biology, Mar 12, 2016
Current Zoology, Jun 1, 2012
Nature Ecology and Evolution, Nov 9, 2020
Evolution, Nov 29, 2016
Observations of male mate choice are increasingly common, even in species with traditional sex ro... more Observations of male mate choice are increasingly common, even in species with traditional sex roles. In addition, female traits that bear the hallmarks of secondary sexual characters are increasingly reported. These concurrent empirical trends have led to the repeated inference that, even under polygyny, male mate choice is a mechanism of sexual selection on female traits. It is often either assumed or argued that in these cases females are competing for males of superior "quality"; females might experience sexual selection under polygyny if they compete for mates that provide either direct or indirect benefits. However, the theoretical foundation of this testable hypothesis remains largely uninvestigated. We develop a population genetic model to probe the logic of this hypothesis and demonstrate that, contrary to common inferences, male mate choice, variation in male quality (in the form of a direct fecundity benefit to females), and female ornamentation can coexist in a population without any sexual selection on female ornamentation taking place at all. Furthermore, even in a "best case scenario" where high quality males with a preference for ornamented females are able to mate disproportionately more often with them, the evolution of female traits by sexual selection may be relatively weak. We discuss the implication of these findings for ongoing empirical and theoretical research on the evolution of sexual-signaling in females.
The American Naturalist, 2009
Male mate selection during polygyny traditionally has been eclipsed in the literature by its fema... more Male mate selection during polygyny traditionally has been eclipsed in the literature by its female counterpart. Existing models that have studied male mate choice have concluded that males with genetically inherited preferences for females exhibiting particular traits are often less fit than males without such a preference, leading to preference loss. In this article, we explore the consequences of a fundamental difference between male and female mate choice, the way in which the opposite sex acts as a resource during mating. By incorporating a strategic process at the ecological level, we show that if males are allowed to actively adjust the distribution of their courtship efforts over the available classes of females, male preference can be maintained as a polymorphism. Further, the resulting coexistence induces a reproductive segregation within the population that, when coupled with genetic control of female traits, can lead to strong linkage disequilibrium between the alleles for trait and preference. These processes can cause complete assortative mating to emerge in the model.
PLOS Biology, Oct 2, 2023
Cold Spring Harbor Perspectives in Biology, Jan 7, 2024
Evolution, Jan 3, 2022
The strength of mate choice (choosiness) often varies with age, but theory to understand this var... more The strength of mate choice (choosiness) often varies with age, but theory to understand this variation is scarce. Additionally, theory has investigated the evolution of choosiness in speciation scenarios but has ignored that most organisms have overlapping generations. We investigate whether speciation can result in variation of choosiness with age, and whether such variation can in turn affect speciation. We develop a population‐genetic model of the evolution of choosiness in organisms with overlapping generations in the context of secondary contact between two divergent populations. We assume that females choose males that match their phenotype, such that choosiness evolves by sexual selection. We demonstrate that speciation can result in the evolution of age‐specific choosiness when the mating trait is under divergent ecological selection and age is not used as a mating cue. The cause of this result is that allele frequencies differ between choosy females and males. However, we find that the evolution of age‐specific choosiness does not affect the overall level of reproductive isolation compared to a case without age‐structure, supporting previous speciation theory. Overall, our results connect life history and speciation theory, and the mechanisms that we highlight have implications for the understanding of the role of sex‐specific selection in the evolution of choosiness.
Carolina Digital Repository (University of North Carolina at Chapel Hill), 2011
Evolution, Aug 12, 2014
Male ejaculates include large amounts of seminal fluid proteins (Sfps) that influence male sperm ... more Male ejaculates include large amounts of seminal fluid proteins (Sfps) that influence male sperm competitive success. In spite of their diverse proximate functions, Sfps involved in sperm competition increase male fitness in one of three ways: (1) "avoidance" proteins help males avoid sperm competition, (2) "defense" proteins help males defend their sperm from displacement by the female's subsequent mate, and (3) "offense" proteins aid males in displacing sperm of preceding males. Here, we present a population genetic model of the evolution of allocation of finite resources by males to the three kinds of Sfps. We analyze the influence of relative efficiencies of different Sfps, of plasticity in resource allocation, and of differences in viability costs of Sfps. We find that in absence of plasticity or different viability costs, equal investment in defense and offense Sfps evolves, irrespective of their relative efficiency. In all cases, males evolve to invest more in avoidance when avoidance proteins are increasingly efficient, and when offense is more efficient than defense. Differences in viability costs result in lower investment in costly proteins, whereas plasticity has complex effects, influencing both the optimal seminal fluid composition and maintenance of variation in investment in these proteins across populations.
bioRxiv (Cold Spring Harbor Laboratory), Mar 14, 2023
Evolution, Feb 9, 2023
Sexual selection has a rich history of mathematical models that consider why preferences favor on... more Sexual selection has a rich history of mathematical models that consider why preferences favor one trait phenotype over another (for population genetic models) or what specific trait value is preferred (for quantitative genetic models). Less common is exploration of the evolution of choosiness or preference strength: i.e., by how much a trait is preferred. We examine both population and quantitative genetic models of the evolution of preferences, specifically developing “baseline models” of the evolution of preference strength during the Fisher process. Using a population genetic approach, we find selection for stronger and stronger preferences when trait variation is maintained by mutation. However, this force is quite weak and likely to be swamped by drift in moderately-sized populations. In a quantitative genetic model, unimodal preferences will generally not evolve to be increasingly strong without bounds when male traits are under stabilizing viability selection, but evolve to extreme values when viability selection is directional. Our results highlight that different shapes of fitness and preference functions lead to qualitatively different trajectories for preference strength evolution ranging from no evolution to extreme evolution of preference strength.
Ecology and Evolution, Mar 6, 2018
Journal of Evolutionary Biology, Mar 12, 2016
Current Zoology, Jun 1, 2012
Nature Ecology and Evolution, Nov 9, 2020
Evolution, Nov 29, 2016
Observations of male mate choice are increasingly common, even in species with traditional sex ro... more Observations of male mate choice are increasingly common, even in species with traditional sex roles. In addition, female traits that bear the hallmarks of secondary sexual characters are increasingly reported. These concurrent empirical trends have led to the repeated inference that, even under polygyny, male mate choice is a mechanism of sexual selection on female traits. It is often either assumed or argued that in these cases females are competing for males of superior "quality"; females might experience sexual selection under polygyny if they compete for mates that provide either direct or indirect benefits. However, the theoretical foundation of this testable hypothesis remains largely uninvestigated. We develop a population genetic model to probe the logic of this hypothesis and demonstrate that, contrary to common inferences, male mate choice, variation in male quality (in the form of a direct fecundity benefit to females), and female ornamentation can coexist in a population without any sexual selection on female ornamentation taking place at all. Furthermore, even in a "best case scenario" where high quality males with a preference for ornamented females are able to mate disproportionately more often with them, the evolution of female traits by sexual selection may be relatively weak. We discuss the implication of these findings for ongoing empirical and theoretical research on the evolution of sexual-signaling in females.
The American Naturalist, 2009
Male mate selection during polygyny traditionally has been eclipsed in the literature by its fema... more Male mate selection during polygyny traditionally has been eclipsed in the literature by its female counterpart. Existing models that have studied male mate choice have concluded that males with genetically inherited preferences for females exhibiting particular traits are often less fit than males without such a preference, leading to preference loss. In this article, we explore the consequences of a fundamental difference between male and female mate choice, the way in which the opposite sex acts as a resource during mating. By incorporating a strategic process at the ecological level, we show that if males are allowed to actively adjust the distribution of their courtship efforts over the available classes of females, male preference can be maintained as a polymorphism. Further, the resulting coexistence induces a reproductive segregation within the population that, when coupled with genetic control of female traits, can lead to strong linkage disequilibrium between the alleles for trait and preference. These processes can cause complete assortative mating to emerge in the model.