Sexual selection: a dynamic state of affairs (original) (raw)

A functional approach to sexual selection

Functional Ecology, 2007

Sexual selection theory is a robust and dynamic field within evolutionary biology, yet despite decades of research, remarkably little is known of the mechanistic bases of mate choice and male competition. 2. Because many aspects of sexual selection involve dynamic movements, and are physically challenging, the limits of sexual selection may be defined by key functional and physiological variables (i.e. the 'functional approach'). 3. We advocate the functional approach for providing mechanistic resolution on the adaptive basis of sexual structures and signals, the nature of mate choice and how males compete, among other issues.

Endless forms of sexual selection

2019

The field of sexual selection has burgeoned with research into trait evolution in the context of ecology, sociality, phylogeny, natural selection, and sexual conflict. This paper is the product of a "stock-taking" workshop; our aim is to stimulate discussion, not to provide an exhaustive review. We identify outstanding questions organized into four thematic sections. 1) Evolution of mate choice and mating systems. Variation in mate quality can generate mating competition and choice in either sex with implications for the evolution of mating systems. Limitations on mate choice may dictate the importance of direct vs. indirect benefits in mating decisions and consequently, mating systems. Specifically, polyandry evolves in response to the strength of pre-vs. post-copulatory selection. The evolution of polyandry may be related to diversity of pathogens and Major Histocompatibility Complex (MHC) genes. MHC genes are also potential cues of kinship in avoidance of inbreeding. The balance between inbreeding avoidance and inclusive fitness in mating decisions deserves greater attention. 2) Sender and receiver mechanisms shaping signal design. Mediation of honest signal content likely depends on integration of temporally variable social and physiological costs that are a challenge to measure. The neuroethology of sensory and cognitive receiver biases is the main key to signal form and the 'aesthetic sense' proposed by Darwin. Since a receiver bias is sufficient to both start and drive ornament or armament exaggeration, without a genetically correlated or even coevolving receiver, this may be the appropriate 'null model' of sexual selection. 3) Genetic architecture of sexual selection. Despite advances in modern molecular techniques, the number and identity of genes underlying performance remain largely unknown. A combination of genomic techniques and long-term field studies that reveal ecological correlates of reproductive success is warranted. In-depth investigations into the genetic basis of sexual dimorphism will reveal constraints and trajectories of sexually selected trait evolution. 4) Sexual selection and conflict as drivers of speciation. Population divergence and speciation is often

Sexual selection and mate choice

Trends in Ecology & Evolution, 2006

The past two decades have seen extensive growth of sexual selection research. Theoretical and empirical work has clarified many components of pre-and postcopulatory sexual selection, such as aggressive competition, mate choice, sperm utilization and sexual conflict. Genetic mechanisms of mate choice evolution have been less amenable to empirical testing, but molecular genetic analyses can now be used for incisive experimentation. Here, we highlight some of the currently debated areas in pre-and postcopulatory sexual selection. We identify where new techniques can help estimate the relative roles of the various selection mechanisms that might work together in the evolution of mating preferences and attractive traits, and in sperm-egg interactions.

Sexual Selection: Biology and Behavior

Bulletin of the Entomological Society of America, 1985

area of research understandable, by giving key examples, elucidating problems, reviewing mechanisms (when known), and providing insights for future work. In summary, thc author has succeeded in bringing the disciplines of microbial and disease control into sharp focus, listing their advantages, disadvantages, as well as discussing thc interrelationships between "pure" and "applicd" biology. Finally, I cnvy the students at the University of Edinburgh who have had the opportunity to attcnd Dr. Deacon's classes. His enthusiasm, clarity, and understanding of these areas comes through quite clearly in this enjoyable book.

Sexual Development and the Environment: Conclusions from 40 Years of Theory

Sexual Development, 2021

In this review, we consider the insight that has been gained through theoretical examination of environmental sex determination (ESD) and thermolability – how theory has progressed our understanding of the ecological and evolutionary dynamics associated with ESD, the transitional pathways between different modes of sex determination, and the underlying mechanisms. Following decades of theory on the adaptive benefits of ESD, several hypotheses seem promising. These hypotheses focus on the importance of differential fitness (sex-specific effects of temperature on fitness) in generating selection for ESD, but highlight alternative ways differential fitness arises: seasonal impacts on growth, sex-specific ages of maturation, and sex-biased dispersal. ESD has the potential to generate biased sex ratios quite easily, leading to complex feedbacks between the ecology and evolution of ESD. Frequency-dependent selection on sex acts on ESD-related traits, driving local adaptation or plasticity...

Sex in an Evolutionary Perspective: Just Another Reaction Norm

It is common to refer to all sorts of clear-cut differences between the sexes as something that is biologically almost inevitable. Although this does not reflect the status of evolutionary theory on sex determination and sexual dimorphism, it is probably a common view among evolutionary biologists as well, because of the impact of sexual selection theory. To get away from thinking about biological sex and traits associated with a particular sex as something static, it should be recognized that in an evolutionary perspective sex can be viewed as a reaction norm, with sex attributes being phenotypically plastic. Sex determination itself is fundamentally plastic, even when it is termed ''genetic''. The phenotypic expression of traits that are statistically associated with a particular sex always has a plastic component. This plasticity allows for much more variation in the expression of traits according to sex and more overlap between the sexes than is typically acknowledged. Here we review the variation and frequency of evolutionary changes in sex, sex determination and sex roles and conclude that sex in an evolutionary time-frame is extremely variable. We draw on recent findings in sex determination mechanisms, empirical findings of morphology and behaviour as well as genetic and developmental models to explore the concept of sex as a reaction norm. From this point of view, sexual differences are not expected to generally fall into neat, discrete, pre-determined classes. It is important to acknowledge this variability in order to increase objectivity in evolutionary research.