Intralocus Tactical Conflict and the Evolution of Alternative Reproductive Tactics

Morris, Molly R.; Goedert, Débora; Abbott, Jessica K.; Robinson, Donelle M.; Ríos-Cardenas, Oscar

doi:10.1016/b978-0-12-407186-5.00007-0

Cited by 36 publications

(74 citation statements)

References 85 publications

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“…This is probably due to the fact that our phylogenies differed from each other mostly in the level of relationships among subfamilies, whereas most of the transitions in dimorphisms (especially in male dimorphism) occurred within subfamilies, rather than in the common ancestor of two or more subfamilies. We suggest that the major force behind the relationship between sexual and male dimorphism is the similarity in selection against intralocus sexual conflict (Rice and Chippindale ) and against intralocus tactical conflict (Morris et al ). Additionally, sexual dimorphism in sexually selected traits might evolve more readily than male dimorphism for at least two reasons: (1) the genetic architecture for sex‐specific expression is already present even in sexually monomorphic species, due to sex chromosomes or autosomal genes with sex‐limited expression, whereas the same is not true for male dimorphism; and (2) there is a greater opportunity for the evolution of sexual dimorphism than for the evolution of male dimorphism because secondary sexual traits are selected against in all females, but only in a fraction of males (minors).…”

Section: Discussionmentioning

confidence: 93%

Correlated Evolution of Sexual Dimorphism and Male Dimorphism in a Clade of Neotropical Harvestmen

et al. 2014

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Secondary sexual traits increase male fitness, but may be maladaptive in females, generating intralocus sexual conflict that is ameliorated through sexual dimorphism. Sexual selection on males may also lead some males to avoid expenditure on secondary sexual traits and achieve copulations using alternative reproductive tactics (ARTs). Secondary sexual traits can increase or decrease fitness in males, depending on which ART they employ, generating intralocus tactical conflict that can be ameliorated through male dimorphism. Due to the evolutionary forces acting against intralocus sexual and tactical conflicts, male dimorphism could coevolve with sexual dimorphism, a hypothesis that we tested by investigating these dimorphisms across 48 harvestman species.Using three independently derived phylogenies, we consistently found that the evolution of sexual dimorphism was correlated with that of male dimorphism, and suggest that the major force behind this relationship is the similarity between selection against intralocus sexual conflict and selection against intralocus tactical conflict. We also found that transitions in male dimorphism were more likely in the presence of sexual dimorphism, indicating that if a sexually selected trait arises on an autosome and is expressed in both sexes, its suppression in females probably evolves earlier than its suppression in small males that adopt ARTs. K E Y W O R D S :Alternative phenotypes, coevolution, intralocus sexual conflict, intralocus tactical conflict, intrasexual dimorphism, Opiliones.

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Section: Discussionmentioning

confidence: 93%

Correlated Evolution of Sexual Dimorphism and Male Dimorphism in a Clade of Neotropical Harvestmen

et al. 2014

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“…This shared genetic architecture cannot be assumed, nor can it be inferred from the functions of the traits of males and females, or males of different morphs. However, as we argued above, genetic correlations between the sexes (and especially between morphs within a sex) are probably prevalent and would be the most straightforward way to investigate the third element of ISC and ITC (Morris et al ., ).…”

Section: Introductionmentioning

confidence: 97%

“…We predicted that body size and general shape traits (pronotum width, elytra length, and rear and front femur lengths) would not have strikingly different phenotypic optima between the sexes and male morphs, and therefore would present positive intersexual and intrasexual genetic correlations. On the other hand, as horn length is sexually selected in majors only, this trait is expected to have different phenotypic optima between male morphs, and should present a reduction or complete breakdown of intrasexual genetic correlations as a result of ITC (Morris et al ., ). In summary, we expected significant and positive intersexual genetic correlations for all traits, with the obvious exception of horn length, which is not expressed in females.…”

Section: Introductionmentioning

confidence: 97%

Intralocus tactical conflict: genetic correlations between fighters and sneakers of the dung beetle Onthophagus taurus

Buzatto

Kotiaho

Tomkins

et al. 2015

J of Evolutionary Biology

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Males and females differ in their phenotypic optima for many traits, and as the majority of genes are expressed in both sexes, some alleles can be beneficial to one sex but harmful to the other (intralocus sexual conflict; ISC). ISC theory has recently been extended to intrasexual dimorphisms, where certain alleles may have opposite effects on the fitness of males of different morphs that employ alternative reproductive tactics (intralocus tactical conflict; ITC). Here, we use a half-sib breeding design to investigate the genetic basis for ISC and ITC in the dung beetle Onthophagus taurus. We found positive heritabilities and intersexual genetic correlations for almost all traits investigated. Next, we calculated the intrasexual genetic correlation between males of different morphs for horn length, a sexually selected trait, and compared it to intrasexual correlations for naturally selected traits in both sexes. Intrasexual genetic correlations did not differ significantly between the sexes or between naturally and sexually selected traits, failing to support the hypothesis that horns present a reduction of intrasexual genetic correlations due to ITC. We discuss the implications for the idea of developmental reprogramming between male morphs and emphasize the importance of genetic correlations as constraints for the evolution of dimorphisms.

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“…The result is typically that in neither sex the optimal trait value is reached (Bonduriansky and Chenoweth 2009). In male-dimorphic species, each male morph has inherently different optimal trait values (Morris et al 2013). These different trait values will generate a stronger or weaker IASC between males and females—depending on the mismatch with female optimal trait values.…”

Section: Discussionmentioning

confidence: 99%

“…IASC occurs when males and females (1) share a genetic architecture for a certain phenotypic trait, (2) have different phenotypic trait optima, and (3) neither sex is at its optimal trait expression (Morris et al 2013). IASCs revolve around sex-specific trait optima for life-history, morphology, behaviour or physiology (Adler and Bonduriansky 2014).…”

Section: Introductionmentioning

confidence: 99%

Life-history consequences of bidirectional selection for male morph in a male-dimorphic bulb mite

Beuken

Smallegange

2018

Exp Appl Acarol

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Intralocus sexual conflict (IASC) arises when males and females have different trait optima. Some males pursue different alternative reproductive tactics (ARTs) with different trait optima, resulting in different strengths of IASC. Consequently, for instance daughter fitness is differentially affected by her sire’s morph. We tested if—and which—other life-history traits correlatively change in bidirectional, artificial selection experiments for ARTs. We used the male-dimorphic bulb mite Rhizoglyphus robini, the males of which are high-fitness ‘fighters’ or low-fitness ‘scramblers’. Twice in each of the five generations of selection, we assessed clutch composition (number of mites of the various life stages present) and size (total number of offspring). Furthermore, we tracked offspring from egg to adulthood in the first and final generation to detect differences between selection lines in the size and duration of stages, and in maturation time. We found that selection for male morph increased the frequency of that morph. Furthermore, compared to fighter lines, scrambler lines produced more females, which laid larger eggs (in the final generations), and maintained a higher egg-laying rate for longer. Otherwise, our results showed no consistent differences between the selection lines in clutch size and composition, life stage size or duration, or maturation time. Though we found few correlated life-history trait changes in response to selection on male morph, the differences in egg laying rate and egg size suggest that IASC between fighters is costlier to females than IASC with scramblers. We hypothesize that these differences in reproductive traits allow fighter-offspring to perform better in small, declining populations but scrambler-offspring to perform better in large, growing populations.Electronic supplementary materialThe online version of this article (10.1007/s10493-018-0320-5) contains supplementary material, which is available to authorized users.

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Intralocus Tactical Conflict and the Evolution of Alternative Reproductive Tactics

Cited by 36 publications

References 85 publications

Correlated Evolution of Sexual Dimorphism and Male Dimorphism in a Clade of Neotropical Harvestmen

Correlated Evolution of Sexual Dimorphism and Male Dimorphism in a Clade of Neotropical Harvestmen

Intralocus tactical conflict: genetic correlations between fighters and sneakers of the dung beetle Onthophagus taurus

Life-history consequences of bidirectional selection for male morph in a male-dimorphic bulb mite

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