scholarly journals The paradox of obligate sex: the roles of sexual conflict and mate scarcity in transitions to facultative and obligate asexuality

2017 ◽  
Author(s):  
Nathan W Burke ◽  
Russell Bonduriansky
Keyword(s):  
Sexual Conflict ◽  
Reproductive Strategies ◽  
Mutant Allele ◽  
Complete Loss ◽  
Recent Theory ◽  
Female Resistance ◽  
Evolutionary Trap ◽  
Individual Based Models ◽  
Parthenogenetic Reproduction ◽  
Sexually Antagonistic Coevolution

ABSTRACTRecent theory suggests that male coercion could contribute to the maintenance of obligate sex. However, it is unclear how sexually antagonistic coevolution might interact with mate scarcity to influence the probability of invasions of obligately sexual populations by mutants capable of parthenogenetic reproduction. Furthermore, if invasion does occur, it is unclear which factors promote or prevent the complete loss of sex. Using individual-based models, we show that male coercion cannot prevent the invasion of a mutant allele that gives virgin females the ability to reproduce parthenogenetically because mutants always benefit by producing at least some offspring asexually prior to mating. Indeed, the likelihood of invasion generally increases as sexual conflict intensifies, and the effects of sexual conflict and mate scarcity can interact in complex ways to promote invasion. Nonetheless, we find that coercion prevents the complete loss of sex unless linkage disequilibrium can build up between the mutant allele and alleles for effective female resistance. Our findings clarify how costs and limitations of female resistance can promote the maintenance of sexual reproduction, turning sex into an evolutionary trap. At the same time, our results highlight the need to explain why facultative reproductive strategies so rarely evolve in nature.

scholarly journals Sexual conflict and STIs: coevolution of sexually antagonistic host traits with a sexually transmitted infection

2017 ◽  
Author(s):  
Alison M. Wardlaw ◽  
Aneil F. Agrawal
Keyword(s):  
Sexual Conflict ◽  
Sexually Transmitted Infection ◽  
Female Mate Choice ◽  
Relative Strength ◽  
Female Resistance ◽  
Transmitted Infection ◽  
Mating Rate ◽  
Sexually Transmitted ◽  
Establishment Probability ◽  
Sexually Antagonistic Coevolution

AbstractIn many taxa, there is a conflict between the sexes over mating rate. The outcome of sexually antagonistic coevolution depends on the costs of mating and natural selection against sexually antagonistic traits. A sexually transmitted infection (STI) changes the relative strength of these costs. We study the three-way evolutionary interaction between male persistence, female resistance, and STI virulence for two types of STIs: a viability-reducing STI and a reproduction-reducing STI. A viability-reducing STI escalates conflict between the sexes. This leads to increased STI virulence (i.e., full coevolution) if the costs of sexually antagonistic traits occur through viability but not if the costs occur through reproduction. In contrast, a reproduction-reducing STI de-escalates the sexual conflict but STI virulence does not coevolve in response. We also investigated the establishment probability of STIs under different combinations of evolvability. Successful invasion by a viability-reducing STI becomes less likely if hosts (but not parasite) are evolvable, especially if only the female trait can evolve. A reproduction-reducing STI can almost always invade because it does not kill its host. We discuss how the evolution of host and parasite traits in a system with sexual conflict differ from a system with female mate choice.

scholarly journals Quantifying the gender load: can population crosses reveal interlocus sexual conflict?

2006 ◽  
Vol 361 (1466) ◽  
pp. 363-374 ◽  
Author(s):  
Tristan A.F Long ◽  
Robert Montgomerie ◽  
Adam K Chippindale
Keyword(s):  
Sperm Competition ◽  
Sexual Conflict ◽  
Population Differentiation ◽  
Population Divergence ◽  
Mating Frequency ◽  
Female Reproduction ◽  
Female Fitness ◽  
Antagonistic Coevolution ◽  
The Cost ◽  
Sexually Antagonistic Coevolution

Six sister populations of Drosophila melanogaster kept under identical environmental conditions for greater than 600 generations were reciprocally crossed to investigate the incidence of population divergence in allopatry. Population crosses directly influenced fitness, mating frequency, and sperm competition patterns. Changes in both female remating rate and the outcome of male sperm competition (P 1 , P 2 ) in response to foreign males were consistent with intersexual coevolution. Moreover, seven of the 30 crosses between foreign mates resulted in significant reductions in female fitness, whereas two resulted in significant increases, compared to local matings. This tendency for foreign males to reduce female fitness may be interpreted as evidence for either sexually antagonistic coevolution or the disruption of mutualistic interactions. However, instances in which female fitness improved via cohabitation with foreign males may better reveal sexual conflict, signalling release from the cost of interacting with locally adapted males. By this metric, female reproduction in D. melanogaster is strongly constrained by local adaptation by males, a situation that would promote antagonistic coevolution between the sexes. We conclude that sexual selection can promote population differentiation in allopatry and that sexual conflict is likely to have played a role in population differentiation in this study system.

scholarly journals Sexual conflict and correlated evolution between male persistence and female resistance traits in the seed beetle Callosobruchus maculatus

2017 ◽  
Vol 284 (1855) ◽  
pp. 20170132 ◽  
Author(s):  
Liam R. Dougherty ◽  
Emile van Lieshout ◽  
Kathryn B. McNamara ◽  
Joe A. Moschilla ◽  
Göran Arnqvist ◽  
...  
Keyword(s):  
Sexual Conflict ◽  
Male Genitalia ◽  
Callosobruchus Maculatus ◽  
Negative Relationship ◽  
Female Reproductive Tract ◽  
Female Resistance ◽  
Correlated Evolution ◽  
Male And Female ◽  
Seed Beetle ◽  
Trade Offs

Traumatic mating (or copulatory wounding) is an extreme form of sexual conflict whereby male genitalia physically harm females during mating. In such species females are expected to evolve counter-adaptations to reduce male-induced harm. Importantly, female counter-adaptations may include both genital and non-genital traits. In this study, we examine evolutionary associations between harmful male genital morphology and female reproductive tract morphology and immune function across 13 populations of the seed beetle Callosobruchus maculatus . We detected positive correlated evolution between the injuriousness of male genitalia and putative female resistance adaptations across populations. Moreover, we found evidence for a negative relationship between female immunity and population productivity, which suggests that investment in female resistance may be costly due to the resource trade-offs that are predicted between immunity and reproduction. Finally, the degree of female tract scarring (harm to females) was greater in those populations with both longer aedeagal spines and a thinner female tract lining. Our results are thus consistent with a sexual arms race, which is only apparent when both male and female traits are taken into account. Importantly, our study provides rare evidence for sexually antagonistic coevolution of male and female traits at the within-species level.

scholarly journals Sensory exploitation and sexual conflict

2006 ◽  
Vol 361 (1466) ◽  
pp. 375-386 ◽  
Author(s):  
Göran Arnqvist
Keyword(s):  
Sexual Dimorphism ◽  
Sexual Conflict ◽  
Theoretical Models ◽  
Sensory Exploitation ◽  
Subsequent Evolution ◽  
Female Preferences ◽  
General Importance ◽  
Evolution Of Resistance ◽  
Sexual Traits ◽  
Sexually Antagonistic Coevolution

Much of the literature on male–female coevolution concerns the processes by which male traits and female preferences for these can coevolve and be maintained by selection. There has been less explicit focus on the origin of male traits and female preferences. Here, I argue that it is important to distinguish origin from subsequent coevolution and that insights into the origin can help us appreciate the relative roles of various coevolutionary processes for the evolution of diversity in sexual dimorphism. I delineate four distinct scenarios for the origin of male traits and female preferences that build on past contributions, two of which are based on pre-existing variation in quality indicators among males and two on exploitation of pre-existing sensory biases among females. Recent empirical research, and theoretical models, suggest that origin by sensory exploitation has been widespread. I argue that this points to a key, but perhaps transient, role for sexually antagonistic coevolution (SAC) in the subsequent evolutionary elaboration of sexual traits, because (i) sensory exploitation is often likely to be initially costly for individuals of the exploited sex and (ii) the subsequent evolution of resistance to sensory exploitation should often be associated with costs due to selective constraints. A review of a few case studies is used to illustrate these points. Empirical data directly relevant to the costs of being sensory exploited and the costs of evolving resistance is largely lacking, and I stress that such data would help determining the general importance of sexual conflict and SAC for the evolution of sexual dimorphism.

scholarly journals Offspring viability benefits but no apparent costs of mating with high quality males

2010 ◽  
Vol 7 (3) ◽  
pp. 419-421 ◽  
Author(s):  
Leigh W. Simmons ◽  
Rebecca Holley
Keyword(s):  
Sexual Selection ◽  
Sexual Conflict ◽  
Alternative Hypothesis ◽  
Dung Beetle ◽  
Male Courtship ◽  
High Quality ◽  
Female Resistance ◽  
Genetic Quality ◽  
Onthophagus Taurus ◽  
Courtship Signals

Traditional models of sexual selection posit that male courtship signals evolve as indicators of underlying male genetic quality. An alternative hypothesis is that sexual conflict over mating generates antagonistic coevolution between male courtship persistence and female resistance. In the scarabaeine dung beetle Onthophagus taurus , females are more likely to mate with males that have high courtship rates. Here, we examine the effects of exposing females to males with either high or low courtship rates on female lifetime productivity and offspring viability. Females exposed to males with high courtship rates mated more often and produced offspring with greater egg–adult viability. Female productivity and lifespan were unaffected by exposure to males with high courtship rates. The data are consistent with models of sexual selection based on indirect genetic benefits, and provide little evidence for sexual conflict in this system.

scholarly journals Escalation and constraints of antagonistic armaments in water striders

2018 ◽  
Author(s):  
Antonin Jean Johan Crumière ◽  
David Armisén ◽  
Aïdamalia Vargas-Lowman ◽  
Martha Kubarakos ◽  
Felipe Ferraz Figueiredo Moreira ◽  
...  
Keyword(s):  
Natural Selection ◽  
Sexual Conflict ◽  
Natural Variation ◽  
Evolutionary Dynamics ◽  
Arms Race ◽  
Trade Off ◽  
Antagonistic Coevolution ◽  
Water Striders ◽  
Mating Performance ◽  
Sexually Antagonistic Coevolution

AbstractSexual conflict may result in the escalating coevolution of sexually antagonistic traits. However, our understanding of the evolutionary dynamics of antagonistic traits and their role in association with sex-specific escalation remains limited. Here we study sexually antagonistic coevolution in a genus of water striders called Rhagovelia. We identified a set of male grasping traits and female anti-grasping traits used during pre-mating struggles and show that natural variation of these traits is associated with variation in mating performance in the direction expected for antagonistic co-evolution. Phylogenetic mapping detected signals of escalation of these sexually antagonistic traits suggesting an ongoing arms race. Moreover, their escalation appears to be constrained by a trade-off with dispersal through flight in both sexes. Altogether our results highlight how sexual interactions may have shaped sex-specific antagonistic traits and how constraints imposed by natural selection may have influenced their evolution.

scholarly journals Atypical mating in a scorpionfly without a notal organ

2015 ◽  
Vol 84 (4) ◽  
pp. 305-315 ◽  
Author(s):  
Wen Zhong ◽  
Zi-Yi Qi ◽  
Bao-Zhen Hua
Keyword(s):  
Structural Foundation ◽  
Sexual Dimorphism ◽  
Salivary Glands ◽  
Sexual Conflict ◽  
Mating Behaviour ◽  
Salivary Secretion ◽  
Mating Pattern ◽  
Nuptial Gifts ◽  
Female Resistance ◽  
Male And Female

Firm coupling of genitalia is critical for copulation in most groups of insects. To counter female resistance that usually breaks off genital connection, male scorpionflies (Mecoptera: Panorpidae) usually provide nuptial gifts for the female and seize their mates with grasping devices. The notal organ, a modified clamp on tergum III of male scorpionflies, plays a significant role in seizing the female wings and helping maintain mating position during copulation. The mating behaviour remains unknown for the scorpionfly Furcatopanorpa longihypovalva (Hua and Cai, 2009) whose male lacks a notal organ. In this paper, we first attempt to study the mating behaviour of F. longihypovalva. The results show that the male provides liquid salivary secretion through a mouth-to-mouth mode for the female, and maintains copulation mainly by continuous provision of salivary secretion rather than by seizing the female with grasping devices. Thus the male copulates with the female in an atypical O-shaped position, with only their mouthparts and genitalia connected to each other. The salivary glands exhibit remarkable sexual dimorphism: short and bifurcated in the female, but well-developed and multi-furcated in the male. The extremely developed salivary glands of the male lay a structural foundation for the male to continuously provide liquid salivary secretion, and to help the male to mediate female resistance, being likely to serve as a compensation to his absence of the notal organ. We also investigated the functional morphology and copulatory mechanism of the male and female genitalia. The evolution of the atypical mating pattern of F. longihypovalva is putatively discussed as an adaptation in the context of sexual conflict.

scholarly journals Sexual conflict in its ecological setting

2018 ◽  
Vol 373 (1757) ◽  
pp. 20170418 ◽  
Author(s):  
Jennifer C. Perry ◽  
Locke Rowe
Keyword(s):  
Sex Differences ◽  
Local Adaptation ◽  
Sexual Conflict ◽  
Ecological Factors ◽  
Ecological Context ◽  
Theme Issue ◽  
Antagonistic Coevolution ◽  
Water Striders ◽  
Sexually Antagonistic Coevolution ◽  
Gaining Insight

Sexual conflict can lead to rapid and continuous coevolution between females and males, without any inputs from varying ecology. Yet both the degree of conflict and selection on antagonistic traits are known to be sensitive to local ecological conditions. This leads to the longstanding question: to what extent does variation in ecological context drive sexually antagonistic coevolution? In water striders, there is much information about the impacts of ecological factors on conflict, and about patterns of antagonistic coevolution. However, the connection between the two is poorly understood. Here, we first review the multiple ways in which ecological context might affect the coevolutionary trajectory of the sexes. We then review ecological and coevolutionary patterns in water striders, and connections between them, in light of theory and new data. Our analysis suggests that ecological variation does impact observed patterns of antagonistic coevolution, but highlights significant uncertainty due to the multiple pathways by which ecological factors can influence conflict and its evolutionary outcome. To the extent that water striders are a reasonable reflection of other systems, this observation serves as both an opportunity and a warning: there is much to learn, but gaining insight may be a daunting process in many systems. This article is part of the theme issue ‘Linking local adaptation with the evolution of sex differences'.

FEMALE RESISTANCE TO MALE HARM EVOLVES IN RESPONSE TO MANIPULATION OF SEXUAL CONFLICT

Evolution ◽  
2004 ◽  
Vol 58 (5) ◽  
pp. 1028 ◽  
Author(s):  
Stuart Wigby ◽  
Tracey Chapman
Keyword(s):  
Sexual Conflict ◽  
Female Resistance
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