Can Sexual Selection Cause Divergence in Mating System–Related Floral Traits?

AbstractPremise of the ResearchThe wide diversity of floral traits seen among plants is shaped by neutral and selective evolutionary processes. In outcrossing species, sexual selection from competing pollen donors is expected to be important for shaping mating system-related traits but empirical evidence is scarce. In a previous evaluation of experimental evolution lines crossed with either one or two pollen donors (monogamous, M, or polyandrous, P, lines) at early floral stages in mixed-mating Collinsia heterophylla (Plantaginaceae), P showed enhanced pollen competitive ability and reduced maternal seed set compared to M, in accordance with sexually antagonistic evolution of pollen. Here, we asked whether the presence of sexual selection during pollen competition affect mating system-related floral traits in the same lines.MethodologyWe compared flowering start, timing of anther-stigma contact (as an indication of timing of self-pollination), timing of stigma receptivity and first seed set between M and P, and with a source line, S (starting material). The former three traits are later in outcrossers than in selfers of Collinsia. The latter trait was expected to be earlier in P than in M because of sexual selection for early seed siring of pollen.Pivotal ResultsArtificial polyandry for four generations resulted in later flowering start and later anther-stigma contact in P compared to M, and the latter trait was intermediate in S. Thus, P appeared more ‘outcrossing’ than M. Stigma receptivity did not differ between lines. First seed set was earlier in P than in M, as expected from sexual selection.ConclusionsOur results from C. heterophylla experimental evolution lines suggest that a component of sexual selection during outcross pollination could enhance the patterns of floral divergence commonly found between outcrossers and selfers.

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Adaptation of floral traits and mating system to pollinator unpredictibility: the case of Disterigma stereophyllum (Ericaceae) in southwestern Colombia

Plant Systematics and Evolution ◽

10.1007/s00606-007-0530-5 ◽

2007 ◽

Vol 266 (3-4) ◽

pp. 165-174 ◽

Cited By ~ 9

Author(s):

L. Navarro ◽

G. Ayensa ◽

P. Guitián

Keyword(s):

Mating System ◽

Floral Traits

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Mate Choice, Sex Roles and Sexual Cognition in Vertebrates: Mate Choice Turns Cognition or Cognition Turns Mate Choice?

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.749495 ◽

2021 ◽

Vol 9 ◽

Author(s):

Theodora Fuss

Keyword(s):

Sexual Selection ◽

Mate Choice ◽

Mating System ◽

Cognitive Abilities ◽

Cognitive Skills ◽

Sex Roles ◽

Environmental Changes ◽

Antipredator Behavior ◽

Energy Levels ◽

Problem Solver

The idea of “smart is sexy,” meaning superior cognition provides competitive benefits in mate choice and, therefore, evolutionary advantages in terms of reproductive fitness, is both exciting and captivating. Cognitively flexible individuals perceive and adapt more dynamically to (unpredictable) environmental changes. The sex roles that females and males adopt within their populations can vary greatly in response to the prevalent mating system. Based on how cognition determines these grossly divergent sex roles, different selection pressures could possibly shape the (progressive) evolution of cognitive abilities, suggesting the potential to induce sexual dimorphisms in superior cognitive abilities. Associations between an individual’s mating success, sexual traits and its cognitive abilities have been found consistently across vertebrate species and taxa, providing evidence that sexual selection may well shape the supporting cognitive prerequisites. Yet, while superior cognitive abilities provide benefits such as higher feeding success, improved antipredator behavior, or more favorable mate choice, they also claim costs such as higher energy levels and metabolic rates, which in turn may reduce fecundity, growth, or immune response. There is compelling evidence in a variety of vertebrate taxa that females appear to prefer skilled problem-solver males, i.e., they prefer those that appear to have better cognitive abilities. Consequently, cognition is also likely to have substantial effects on sexual selection processes. How the choosing sex assesses the cognitive abilities of potential mates has not been explored conclusively yet. Do cognitive skills guide an individual’s mate choice and does learning change an individual’s mate choice decisions? How and to which extent do individuals use their own cognitive skills to assess those of their conspecifics when choosing a mate? How does an individual’s role within a mating system influence the choice of the choosing sex in this context? Drawing on several examples from the vertebrate world, this review aims to elucidate various aspects associated with cognitive sex differences, the different roles of males and females in social and sexual interactions, and the potential influence of cognition on mate choice decisions. Finally, future perspectives aim to identify ways to answer the central question of how the triad of sex, cognition, and mate choice interacts.

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Sexually selected females in the monogamous Western Australian seahorse

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2006.3753 ◽

2006 ◽

Vol 274 (1609) ◽

pp. 521-525 ◽

Cited By ~ 41

Author(s):

Charlotta Kvarnemo ◽

Glenn I Moore ◽

Adam G Jones

Keyword(s):

Sexual Selection ◽

Sex Ratio ◽

Mating System ◽

Genetic Study ◽

Mating Success ◽

Male Preference ◽

Monogamous Species ◽

Adult Sex Ratio ◽

Western Australian ◽

Selection Differentials

Studies of sexual selection in monogamous species have hitherto focused on sexual selection among males. Here, we provide empirical documentation that sexual selection can also act strongly on females in a natural population with a monogamous mating system. In our field-based genetic study of the monogamous Western Australian seahorse, Hippocampus subelongatus , sexual selection differentials and gradients show that females are under stronger sexual selection than males: mated females are larger than unmated ones, whereas mated and unmated males do not differ in size. In addition, the opportunity for sexual selection (variance in mating success divided by its mean squared) for females is almost three times that for males. These results, which seem to be generated by a combination of a male preference for larger females and a female-biased adult sex ratio, indicate that substantial sexual selection on females is a potentially important but under-appreciated evolutionary phenomenon in monogamous species.

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Floral trait variation and links to climate in the mixed-mating annual Clarkia pulchella

Botany ◽

10.1139/cjb-2017-0234 ◽

2018 ◽

Vol 96 (7) ◽

pp. 425-435 ◽

Cited By ~ 2

Author(s):

Devin E. Gamble ◽

Megan Bontrager ◽

Amy L. Angert

Keyword(s):

Mating System ◽

Common Garden ◽

Moisture Stress ◽

Floral Traits ◽

Mixed Mating ◽

Floral Trait ◽

Local Climate ◽

Self Fertilization ◽

Clarkia Pulchella ◽

Watering Treatment

The benefits of self-fertilization can vary across environments, leading to selection for different reproductive strategies and influencing the evolution of floral traits. Although stressful conditions have been suggested to favour self-pollination, the role of climate as a driver of mating-system variation is generally not well understood. Here, we investigate the contributions of local climate to intraspecific differences in mating-system traits in Clarkia pulchella Pursh in a common-garden growth chamber experiment. We also tested for plastic responses to soil moisture with watering treatments. Herkogamy (anther–stigma spacing) correlated positively with dichogamy (timing of anther–stigma receptivity) and date of first flower, and northern populations had smaller petals and flowered earlier in response to experimental drought. Watering treatment alone had little effect on traits, and dichogamy unexpectedly decreased with annual precipitation. Populations also differed in phenological response to watering treatment, based on precipitation and winter temperature of their origin, indicating that populations from cool and dry sites have greater plasticity under different levels of moisture stress. While some variation in floral traits is attributable to climate, further investigation into variation in pollinator communities and the indirect effects of climate on mating system can improve our understanding of the evolution of plant mating.

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2. Mating systems, or who goes with whom, and for how long

Sexual Selection: A Very Short Introduction ◽

10.1093/actrade/9780198778752.003.0002 ◽

2018 ◽

pp. 16-33

Author(s):

Leigh W. Simmons

Keyword(s):

Sexual Selection ◽

Mating System ◽

Social Relationships ◽

Breeding Season ◽

Mating Systems ◽

Practical Applications ◽

Multiple Partners ◽

Monogamous Species ◽

Genetic Techniques ◽

Males And Females

‘Mating systems, or who goes with whom, and for how long’ examines the variation in how males and females associate during the breeding season, ranging from brief couplings with multiple partners to lifelong monogamy. It also shows how the discovery that females mate with many partners, even in supposedly monogamous species such as songbirds, was made possible by modern genetic techniques. Variation in mating systems holds considerable implications for the operation of sexual selection. The way that animal mating systems have been explained historically is outlined before considering how a more contemporary understanding of genetic and social relationships has reshaped our thinking and how understanding a species’ mating system can have practical applications.

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Populations with greater flexibility in floral traits modify mating system in response to the pollinator environment

Functional Ecology ◽

10.1111/1365-2435.13093 ◽

2018 ◽

Vol 32 (6) ◽

pp. 1457-1466 ◽

Cited By ~ 6

Author(s):

Lia Leibman ◽

Anne Rowe ◽

Matthew H. Koski ◽

Laura F. Galloway

Keyword(s):

Mating System ◽

Floral Traits

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Sexual dimorphism of the major chela and sex ratio as indicators of the mating system in the estuarine snapping shrimp Alpheus colombiensis Wicksten, 1988 (Decapoda: Caridea: Alpheidae)

Journal of Crustacean Biology ◽

10.1093/jcbiol/ruaa069 ◽

2020 ◽

Vol 40 (6) ◽

pp. 649-656

Author(s):

Juan C Azofeifa-Solano ◽

Jeffrey A Sibaja-Cordero ◽

Ingo S Wehrtmann

Keyword(s):

Sexual Selection ◽

Sexual Dimorphism ◽

Sex Ratio ◽

Mating System ◽

Mate Guarding ◽

Female Size ◽

Monogamous Species ◽

Low Degree ◽

Adult Sex Ratio ◽

Snapping Shrimps

Abstract The sexual selection over traits that favor access to mating partners could promote the emergence of sexual dimorphism when the pressure is different between sexes. Monogamous species are considered to have a low degree of sexual dimorphism. The highly diverse snapping shrimps are usually regarded as monogamous, but the mating system has been studied only in few species. We aimed to provide insights into the mating system and sexual dimorphism of Alpheus colombiensisWicksten, 1988. The adult sex ratio was female biased, and solitary ovigerous females were found, suggesting a temporary mate guarding type of mating system. Our results also revealed sexual dimorphism on the snapping claw, which is larger in males than in females. The male’s snapping claw is probably under sexual selection, which can be mediated by male-male competition or female choice. We also estimated the A. colombiensis female size at maturity at 5.2 ± 0.76 mm. Our results contradict the common idea that snapping shrimps are monogamous species, and support that A. colombiensis probably have a temporary mate guarding (e.g., males can sexually interact with more than one female, in opposition to sexual monogamy). This study also sustains the growing evidence that alpheid shrimps display snapping claw sexual dimorphism.

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