scholarly journals Context-dependent behavioral plasticity compromises disruptive selection on sperm traits in squid

2020 ◽  
Author(s):  
Noritaka Hirohashi ◽  
Noriyosi Sato ◽  
Yoko Iwata ◽  
Satoshi Tomano ◽  
Md Nur E Alam ◽  
...  
Keyword(s):  
Behavioral Plasticity ◽  
Mating Behaviour ◽  
Social Contexts ◽  
Disruptive Selection ◽  
Behavioural Plasticity ◽  
Male Mating ◽  
Reproductive Tactics ◽  
Developmentally Regulated ◽  
Mating Opportunities ◽  
Sperm Traits

Male animals are not given equal mating opportunities under competitive circumstances. Small males often exhibit alternative mating behaviours and produce spermatozoa of higher quality to compensate for their lower chances of winning physical contests against larger competitors [1]. Because the reproductive benefits of these phenotypes depend on social status/agonistic ranks that can change during growth or aging [2], sperm traits should be developed/switched into fitness optima according to their prospects. However, reproductive success largely relies upon social contexts arising instantaneously from intra- and inter-sexual interactions, which deter males from developing extreme traits and instead favour behavioural plasticity. Nevertheless, the extent to which such plasticity influences developmentally regulated alternative sperm traits remains unexplored. Squids of the family Loliginidae are excellent models to investigate this, because they show sophisticated alternative reproductive tactics (ARTs) by which small males, known as “sneakers”, produce longer spermatozoa and perform extra-pair copulation to attach their sperm packages near the female seminal receptacle (SR). In contrast, large “consort” males have shorter spermatozoa and copulate via pair-bonding to insert their sperm packages near the internal female oviduct [3]. In addition, plasticity in male mating behaviour is common in some species while it is either rare or absent in others. Thus, squid ARTs display a broad spectrum of adaptive traits with a complex repertoire in behaviour, morphology and physiology [3].

scholarly journals Context-dependent behavioural plasticity compromises disruptive selection of sperm traits in squid

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256745
Author(s):  
Noritaka Hirohashi ◽  
Noriyosi Sato ◽  
Yoko Iwata ◽  
Satoshi Tomano ◽  
Md. Nur E. Alam ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Mating Behaviour ◽  
Mantle Cavity ◽  
Disruptive Selection ◽  
Behavioural Plasticity ◽  
Reproductive Tactics ◽  
Transitional State ◽  
The Family ◽  
Nearly Continuous ◽  
Selection Of

Sperm morphology is generally uniform within a species due to selective pressures that act to achieve better fertilization outcomes under postcopulatory competitive circumstances. Therefore, polyandry that intensifies post-mating sperm competition should constrain intraspecific sperm polymorphism. Contrary to this paradigm, we previously found that a polyandrous squid, Heterololigo bleekeri, produces dimorphic eusperm (flagellum length dimorphism; FLD), which is closely associated with alternative reproductive tactics (ARTs); large males (consorts) transfer their spermatophores inside the female’s mantle cavity, while small males (sneakers) do so outside the mantle. Thus, FLD was considered as the consequence of different insemination strategies that arise from different modes of sperm competition, sperm storage and the fertilization environment. However, in other squid species showing ARTs, the choice of mating behaviour is rather conditional (i.e., switching mating tactic between consorts and sneakers), which poses the question of whether sperm FLD could have evolved. Here, we investigated five species in the family Loliginidae that exhibit ARTs and found that all species showed sneaker-biased FLD. However, in a species with conditional ARTs, we found FLD rather ambiguous and the testicular somatic index to be nearly continuous among individuals at transitional state, suggesting that plasticity in mating behaviour compromises the disruptive selection on a sperm morphological trait.

scholarly journals Phenotypic and genomic plasticity of alternative male reproductive tactics in sailfin mollies

2014 ◽  
Vol 281 (1781) ◽  
pp. 20132310 ◽  
Author(s):  
Bonnie A. Fraser ◽  
Ilana Janowitz ◽  
Margaret Thairu ◽  
Joseph Travis ◽  
Kimberly A. Hughes
Keyword(s):  
Gene Expression ◽  
Adaptive Evolution ◽  
Mating Behaviour ◽  
Mating Strategies ◽  
Adaptive Plasticity ◽  
Behavioural Plasticity ◽  
Male Mating ◽  
Brain Gene Expression ◽  
Male Reproductive Tactics ◽  
Sailfin Mollies

A major goal of modern evolutionary biology is to understand the causes and consequences of phenotypic plasticity, the ability of a single genotype to produce multiple phenotypes in response to variable environments. While ecological and quantitative genetic studies have evaluated models of the evolution of adaptive plasticity, some long-standing questions about plasticity require more mechanistic approaches. Here, we address two of those questions: does plasticity facilitate adaptive evolution? And do physiological costs place limits on plasticity? We examine these questions by comparing genetically and plastically regulated behavioural variation in sailfin mollies ( Poecilia latipinna ), which exhibit striking variation in plasticity for male mating behaviour. In this species, some genotypes respond plastically to a change in the social environment by switching between primarily courting and primarily sneaking behaviour. In contrast, other genotypes have fixed mating strategies (either courting or sneaking) and do not display plasticity. We found that genetic and plastic variation in behaviour were accompanied by partially, but not completely overlapping changes in brain gene expression, in partial support of models that predict that plasticity can facilitate adaptive evolution. We also found that behavioural plasticity was accompanied by broader and more robust changes in brain gene expression, suggesting a substantial physiological cost to plasticity. We also observed that sneaking behaviour, but not courting, was associated with upregulation of genes involved in learning and memory, suggesting that sneaking is more cognitively demanding than courtship.

scholarly journals Alternative phenotypes of male mating behaviour in the two-spotted spider mite

2013 ◽  
Vol 61 (1) ◽  
pp. 31-41 ◽  
Author(s):  
Yukie Sato ◽  
Maurice W. Sabelis ◽  
Martijn Egas ◽  
Farid Faraji
Keyword(s):  
Spider Mite ◽  
Mating Behaviour ◽  
Male Mating ◽  
Alternative Phenotypes ◽  
Two Spotted Spider Mite

scholarly journals The development of affiliative and coercive reproductive tactics in male chimpanzees

2021 ◽  
Vol 288 (1942) ◽  
pp. 20202679
Author(s):  
Rachna B. Reddy ◽  
Kevin E. Langergraber ◽  
Aaron A. Sandel ◽  
Linda Vigilant ◽  
John C. Mitani
Keyword(s):  
Mating Success ◽  
Sexual Coercion ◽  
Adolescent And Young Adult ◽  
Adolescent Male ◽  
Male Mating ◽  
Adult Males ◽  
Reproductive Tactics ◽  
Males And Females ◽  
First Time ◽  
Older Males

Like many animals, adult male chimpanzees often compete for a limited number of mates. They fight other males as they strive for status that confers reproductive benefits and use aggression to coerce females to mate with them. Nevertheless, small-bodied, socially immature adolescent male chimpanzees, who cannot compete with older males for status nor intimidate females, father offspring. We investigated how they do so through a study of adolescent and young adult males at Ngogo in Kibale National Park, Uganda. Adolescent males mated with nulliparous females and reproduced primarily with these first-time mothers, who are not preferred as mating partners by older males. Two other factors, affiliation and aggression, also influenced mating success. Specifically, the strength of affiliative bonds that males formed with females and the amount of aggression males directed toward females predicted male mating success. The effect of male aggression toward females on mating success increased as males aged, especially when they directed it toward females with whom they shared affiliative bonds. These results mirror sexual coercion in humans, which occurs most often between males and females involved in close, affiliative relationships.

Alternative Reproductive Tactics

2020 ◽  
pp. 429-446
Author(s):  
Shawn Garner ◽  
Bryan Neff
Keyword(s):  
Body Size ◽  
Small Body ◽  
Large Body ◽  
Morphological Differentiation ◽  
Alternative Reproductive Tactics ◽  
Reproductive Tactics ◽  
Aggressive Interactions ◽  
Single Sex ◽  
Female Mimicry ◽  
Mating Opportunities

Alternative reproductive tactics (ARTs) describe variation among individuals of a single sex in the tactics used to obtain mating opportunities. In crustaceans, ARTs have been observed in multiple taxa and take a variety of forms. ARTs are most commonly observed in males and are generally associated with intense competition among males to monopolize access to breeding females. ARTs frequently involve a guard tactic that competes with other males to monopolize access to females, while a second usurper tactic foregos competition with other males and instead obtains mating opportunities through sneaking behavior. Guard and usurper tactics may be expressed conditionally based on a male’s ability to guard a female (e.g. his body size, the abundance of competitors), or may be expressed as discrete phenotypes that can also include morphological differentiation. For example, in Jassa amphipods the guard tactic is associated with large body size and an enlarged “thumb” on the claw that is used in aggressive interactions with other males, while the usurper tactic is associated with small body size and a reduced thumb. The usurper tactic can take two forms in a marine isopod: small males (gamma) use sneaking behavior to avoid competition with large males (alpha), whereas intermediate-sized males (beta) use female mimicry to avoid competition. Overall, ARTs are well-represented in crustaceans, with many opportunities for continued study to better characterize these unique adaptations.

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