| 1. |
- Lindsay, Willow, 1980, et al.
(författare)
-
Endless forms of sexual selection
- 2019
-
Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, the field of sexual selection has exploded, with advances in theoretical and empirical research complementing each other in exciting ways. This perspective piece is the product of a "stock-taking'' workshop on sexual selection and sexual conflict. Our aim is to identify and deliberate on outstanding questions and to stimulate discussion rather than provide a comprehensive overview of the entire field. These questions are organized into four thematic sections we deem essential to the field. First we focus on the evolution of mate choice and mating systems. Variation in mate quality can generate both competition and choice in the opposite 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, especially with regard to polyandry. Second, we focus on how sender and receiver mechanisms shape signal design. Mediation of honest signal content likely depends on integration of temporally variable social and physiological costs that are challenging to measure. We view the neuroethology of sensory and cognitive receiver biases as the main key to signal form and the 'aesthetic sense' proposed by Darwin. Since a receiver bias is sufficient to both initiate and drive ornament or armament exaggeration, without a genetically correlated or even coevolving receiver, this may be the appropriate 'null model' of sexual selection. Thirdly, we focus on the genetic architecture of sexually selected traits. Despite advances in modern molecular techniques, the number and identity of genes underlying performance, display and secondary sexual traits remains largely unknown. In-depth investigations into the genetic basis of sexual dimorphism in the context of long-term field studies will reveal constraints and trajectories of sexually selected trait evolution. Finally, we focus on sexual selection and conflict as drivers of speciation. Population divergence and speciation are often influenced by an interplay between sexual and natural selection. The extent to which sexual selection promotes or counteracts population divergence may vary depending on the genetic architecture of traits as well as the covariance between mating competition and local adaptation. Additionally, post-copulatory processes, such as selection against heterospecific sperm, may influence the importance of sexual selection in speciation. We propose that efforts to resolve these four themes can catalyze conceptual progress in the field of sexual selection, and we offer potential avenues of research to advance this progress.
|
|
| 2. |
- Lindsay, Willow R, et al.
(författare)
-
Endless forms of sexual selection
- 2024
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- 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 driven by an interplay between sexual and natural selection. To what extent sexual selection promotes or counteracts population divergence may differ depending on the genetic architecture of traits as well as covariance between mating competition and local adaptation, if traits have multiple functions and if sensory systems used in mate choice are locally adapted. Also, post-copulatory processes, e.g. selection against heterospecific sperm, may influence the importance of sexual selection. Sexual conflict can shape speciation processes, since mate choice selection on females can restrict gene flow whereas selection on males is permissive.We propose that efforts to resolve these four themes can catalyze conceptual progress in the field of sexual selection.
|
|
| 3. |
- Ninnes, Calum E., et al.
(författare)
-
A receiver bias for red predates the convergent evolution of red color in widowbirds and bishops
- 2015
-
Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 26:4, s. 1212-1218
-
Tidskriftsartikel (refereegranskat)abstract
- In the African widowbirds, icons of sexual selection, bright red plumage colors are agonistic (threat) signals in territorial competition, but in the congeneric bishop birds, color functions remain obscure. In the yellow-crowned bishop, the earliest branching lineage of the genus, an experimentally introduced red color patch gave a competitive advantage over yellow. This indicates agonistic sexual selection for red also in bishops, and that a receiver bias predated the evolution of red coloration in the genus.Preexisting receiver biases are well known and empirically supported alternatives or complements to signal evolution through coevolving mate choice, but largely neglected as drivers of sexually or socially selected agonistic signal evolution. In further pursuit of a recently revealed receiver bias for red agonistic signaling in Euplectes (17 species of widowbirds and bishops), we investigate here its presence in the yellow-crowned bishop (Euplectes afer), a representative of the earliest phylogenetic branch of the genus. In a captive population in southern Spain, where the yellow-crowned bishop is invasive, we staged and filmed 10-min dyadic contests over access to a feeder, between males with experimentally yellow- (control-) and red-painted crown plumage, respectively. Red males secured significantly more time at the feeder, and tended to win more of the limited number of supplant attempts observed. This suggests that the previously demonstrated agonistic signal function of red carotenoid coloration in widowbirds also applies to the bishop birds, and may derive from a receiver bias (aversion) that is substantially older than the convergent gains of red plumage pigmentation in Euplectes, and perhaps also predating the evolution of red in a few other weaverbird (Ploceidae) lineages. Given the similarities in ecology and behavior across Euplectes, the color diversity appears to primarily be a consequence of evolutionary limitations on mechanisms for achieving red coloration.
|
|
| 4. |
- Ninnes, Calum E., et al.
(författare)
-
Are red bishops red enough? On the persistence of a generalized receiver bias in Euplectes
- 2017
-
Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279.
-
Tidskriftsartikel (refereegranskat)abstract
- In the genus Euplectes (17 species of widowbirds and bishops), red carotenoid-based coloration has been found to function in male contest competition over territories and appears to exploit a generalized receiver bias by which redder (more longwave) hues are perceived as more aversive or intimidating. A major piece missing, however, is that among the 5 most extensively red species, forming the clade of "red bishops," the agonistic function has remained unexplored or undetected. Moreover, does the receiver bias remain generalized ("open-ended") after coevolution of the most exaggerated signal phenotypes? In this field experiment with southern red bishops E. orix, we increased the color hue 27 nm, beyond its natural range, and compared the success in territorial competition of these supernormal red males to that of control-red and green (down-manipulated) males. The treatment, but no pre-manipulation colorimetrics or morphometrics, had a significant effect on territory establishment; 76% of super-red males, 45% of control-red males, and 17% of green males were recorded as territory holders at the end of the experiment. The receiver bias, that is, a generalized aversion of redder hues, thus appears to remain after the signal elaboration process, likely (but not necessarily) reinforced by adaptive receiver coevolution, through, for example, exploitation resistance or signal honesty.
|
|
