scholarly journals Accessory male investment can undermine the evolutionary stability of simultaneous hermaphroditism

2009 ◽  
Vol 5 (5) ◽  
pp. 709-712 ◽  
Author(s):  
Nico K. Michiels ◽  
Philip H. Crowley ◽  
Nils Anthes
Keyword(s):  
Sexual Selection ◽  
Parameter Space ◽  
Sex Allocation ◽  
Evolutionary Stability ◽  
Evolutionary Stable Strategy ◽  
Implicit Assumption ◽  
Stable Strategy ◽  
Male Investment ◽  
Simultaneous Hermaphrodites

Sex allocation (SA) models are traditionally based on the implicit assumption that hermaphroditism must meet criteria that make it stable against transition to dioecy. This, however, puts serious constraints on the adaptive values that SA can attain. A transition to gonochorism may, however, be impossible in many systems and therefore realized SA in hermaphrodites may not be limited by conditions that guarantee stability against dioecy. We here relax these conditions and explore how sexual selection on male accessory investments (e.g. a penis) that offer a paternity benefit affects the evolutionary stable strategy SA in outcrossing, simultaneous hermaphrodites. Across much of the parameter space, our model predicts male allocations well above 50 per cent. These predictions can help to explain apparently ‘maladaptive’ hermaphrodite systems.

scholarly journals Sex allocation and investment into pre- and post-copulatory traits in simultaneous hermaphrodites: the role of polyandry and local sperm competition

2013 ◽  
Vol 368 (1613) ◽  
pp. 20120052 ◽  
Author(s):  
Lukas Schärer ◽  
Ido Pen
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Sex Allocation ◽  
Optimal Allocation ◽  
Recent Theory ◽  
Detailed Knowledge ◽  
Female Reproduction ◽  
Sexually Selected Traits ◽  
Simultaneous Hermaphrodites

Sex allocation theory predicts the optimal allocation to male and female reproduction in sexual organisms. In animals, most work on sex allocation has focused on species with separate sexes and our understanding of simultaneous hermaphrodites is patchier. Recent theory predicts that sex allocation in simultaneous hermaphrodites should strongly be affected by post-copulatory sexual selection, while the role of pre-copulatory sexual selection is much less clear. Here, we review sex allocation and sexual selection theory for simultaneous hermaphrodites, and identify several strong and potentially unwarranted assumptions. We then present a model that treats allocation to sexually selected traits as components of sex allocation and explore patterns of allocation when some of these assumptions are relaxed. For example, when investment into a male sexually selected trait leads to skews in sperm competition, causing local sperm competition, this is expected to lead to a reduced allocation to sperm production. We conclude that understanding the evolution of sex allocation in simultaneous hermaphrodites requires detailed knowledge of the different sexual selection processes and their relative importance. However, little is currently known quantitatively about sexual selection in simultaneous hermaphrodites, about what the underlying traits are, and about what drives and constrains their evolution. Future work should therefore aim at quantifying sexual selection and identifying the underlying traits along the pre- to post-copulatory axis.

scholarly journals Sex allocation and sexual conflict in simultaneously hermaphroditic animals

2009 ◽  
Vol 5 (5) ◽  
pp. 705-708 ◽  
Author(s):  
Lukas Schärer ◽  
Tim Janicke
Keyword(s):  
Sexual Selection ◽  
Theoretical Prediction ◽  
Experimental Test ◽  
Sexual Conflict ◽  
Sex Allocation ◽  
Theoretical Work ◽  
Theoretical Research ◽  
Sperm Donor ◽  
Simultaneous Hermaphrodites

Links between sex allocation (SA) and sexual conflict in simultaneous hermaphrodites have been evident since Charnov's landmark paper published 30 years ago. We discuss two links, namely the potential for sexual conflict over SA between sperm donor and recipient, and the importance of post-copulatory sexual selection and the resulting sexual conflict for the evolution of SA. We cover the little empirical and theoretical work exploring these links, and present an experimental test of one theoretical prediction. The link between SA and sexual conflict is an interesting field for future empirical and theoretical research.

scholarly journals Sex allocation conflict and sexual selection throughout the lifespan of eusocial colonies

2018 ◽  
Author(s):  
Piret Avila ◽  
Lutz Fromhage ◽  
Laurent Lehmann
Keyword(s):  
Resource Allocation ◽  
Sexual Selection ◽  
Evolutionary Biology ◽  
Sex Allocation ◽  
Colony Growth ◽  
Eusocial Insects ◽  
Dynamic Resource ◽  
Colony Ontogeny ◽  
Allocation Decisions ◽  
Allocation Strategies

AbstractModels of sex allocation conflict are central to evolutionary biology but have mostly assumed static decisions, where resource allocation strategies are constant over colony lifespan. Here, we develop a model to study how the evolution of dynamic resource allocation strategies is affected by the queen-worker conflict in annual eusocial insects. We demonstrate that the time of dispersal of sexuals affects the sex allocation ratio through sexual selection on males. Furthermore, our model provides three predictions that depart from established results of classic static allocation models. First, we find that the queen wins the sex allocation conflict, while the workers determine the maximum colony size and colony productivity. Second, male-biased sex allocation and protandry evolve if sexuals disperse directly after eclosion. Third, when workers are more related to new queens, then the proportional investment into queens is expected to be lower, which results from the interacting effect of sexual selection (selecting for protandry) and sex allocation conflict (selecting for earlier switch to producing sexuals). Overall, we find that colony ontogeny crucially affects the outcome of sex-allocation conflict because of the evolution of distinct colony growth phases, which decouples how queens and workers affect allocation decisions and can result in asymmetric control.

scholarly journals Males as somatic investment in a parthenogenetic nematode

Science ◽  
2019 ◽  
Vol 363 (6432) ◽  
pp. 1210-1213 ◽  
Author(s):  
Manon Grosmaire ◽  
Caroline Launay ◽  
Marion Siegwald ◽  
Thibault Brugière ◽  
Lilia Estrada-Virrueta ◽  
...  
Keyword(s):  
Game Theory ◽  
Reproductive Strategy ◽  
Evolutionary Stable Strategy ◽  
Stable Strategy ◽  
Sperm Dna

We report the reproductive strategy of the nematode Mesorhabditis belari. This species produces only 9% males, whose sperm is necessary to fertilize and activate the eggs. However, most of the fertilized eggs develop without using the sperm DNA and produce female individuals. Only in 9% of eggs is the male DNA utilized, producing sons. We found that mixing of parental genomes only gives rise to males because the Y-bearing sperm of males are much more competent than the X-bearing sperm for penetrating the eggs. In this previously unrecognized strategy, asexual females produce few sexual males whose genes never reenter the female pool. Here, production of males is of interest only if sons are more likely to mate with their sisters. Using game theory, we show that in this context, the production of 9% males by M. belari females is an evolutionary stable strategy.

scholarly journals Sex‐allocation conflict and sexual selection throughout the lifespan of eusocial colonies

Evolution ◽  
2019 ◽  
Vol 73 (6) ◽  
pp. 1116-1132 ◽  
Author(s):  
Piret Avila ◽  
Lutz Fromhage ◽  
Laurent Lehmann
Keyword(s):  
Sexual Selection ◽  
Sex Allocation

scholarly journals Beyond sex allocation: the role of mating systems in sexual selection in parasitoid wasps

2014 ◽  
Vol 90 (2) ◽  
pp. 599-627 ◽  
Author(s):  
Rebecca A. Boulton ◽  
Laura A. Collins ◽  
David M. Shuker
Keyword(s):  
Sexual Selection ◽  
Sex Allocation ◽  
Mating Systems ◽  
Parasitoid Wasps

scholarly journals Mate limitation and sex ratio evolution

2018 ◽  
Vol 5 (2) ◽  
pp. 171135 ◽  
Author(s):  
Jussi Lehtonen ◽  
Lisa E. Schwanz
Keyword(s):  
Sex Ratio ◽  
Kin Selection ◽  
Sex Allocation ◽  
Evolutionarily Stable Strategy ◽  
Mathematical Relationship ◽  
Stable Strategy ◽  
Local Mate ◽  
Mate Limitation ◽  
Mating Function ◽  
Evolutionarily Stable

Sex ratio evolution has been one of the most successful areas of evolutionary theory. Pioneered by Düsing and Fisher under panmixia, and later extended by Hamilton to cover local mate competition (LMC), these models often assume, either implicitly or explicitly, that all females are fertilized. Here, we examine the effects of relaxing this assumption, under both panmictic and LMC models with diploid genetics. We revisit the question of the mathematical relationship between sex ratio and probability of fertilization, and use these results to model sex ratio evolution under risk of incomplete fertilization. We find that (i) under panmixia, mate limitation has no effect on the evolutionarily stable strategy (ESS) sex allocation; (ii) under LMC, mate limitation can make sex allocation less female-biased than under complete fertilization; (iii) contrary to what is occasionally stated, a significant fraction of daughters can remain unfertilized at the ESS in LMC with mate limitation; (iv) with a commonly used mating function, the fraction of unfertilized daughters can be quite large, and (v) with more realistic fertilization functions, the deviation becomes smaller. The models are presented in three equivalent forms: individual selection, kin selection and group selection. This serves as an example of the equivalence of the methods, while each approach has their own advantages. We discuss possible extensions of the model to haplodiploidy.

scholarly journals Disposable penis and its replenishment in a simultaneous hermaphrodite

2013 ◽  
Vol 9 (2) ◽  
pp. 20121150 ◽  
Author(s):  
Ayami Sekizawa ◽  
Satoko Seki ◽  
Masakazu Tokuzato ◽  
Sakiko Shiga ◽  
Yasuhiro Nakashima
Keyword(s):  
Sexual Selection ◽  
Outer Surface ◽  
Mating Behaviour ◽  
Sperm Storage ◽  
Simultaneous Hermaphrodite ◽  
Storage Organ ◽  
Simultaneous Hermaphrodites

Although it is often thought that sexual selection is weaker in simultaneous hermaphrodites than in gonochorists, some simultaneous hermaphrodites exhibit bizarre mating behaviour. In the simultaneously hermaphroditic nudibranch Chromodoris reticulata , we found a peculiar mating behaviour, wherein the nudibranch autotomized its penis after each copulation and was able to copulate again within 24 h. To have sufficient length to be replenished for three copulations, the penis is compressed and spiralled internally. No other animal is known to repeatedly copulate using such ‘disposable penes’. Entangled sperm masses were observed on the outer surface of the autotomized penis, which is equipped with many backward-pointed spines. There is a possibility that the nudibranch removes sperm already stored in a mating partner's sperm storage organ(s).

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