Shifts in Reproductive Investment in Response to Competitors Lower Male Reproductive Success

Spagopoulou, Foteini; Vega‐Trejo, Regina; Head, Megan L.; Jennions, Michael D.

doi:10.1086/709821

Cited by 11 publications

(10 citation statements)

References 94 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Plastic shifts in male reproductive allocation in response to social competition have been reported for some promiscuous species (e.g. D. melanogaster: Dore et al 2020), including G. holbrooki (Spagopoulou et al 2020). It is therefore surprising that we did not find plasticity in response to the duration of winning or losing experiences for the traits we measured.…”

Section: Plasticity and Body Sizesupporting

confidence: 47%

“…Each block had two sets of the three winner/loser duration treatments (n=12 pairs per block). In each winning/losing trial a focal and a competitor male interacted freely in a 6 L aquarium with a stimulus female (randomly taken from the stock population) present behind a mesh barrier to encourage competitive interactions but prevent mating (Spagopoulou et al 2020). Contest aquaria contained gravel, plastic plants and were lined with black plastic to minimise outside disturbance.…”

Section: Experimental Design: Making Winners and Losersmentioning

confidence: 99%

See 1 more Smart Citation

The effect of brief or prolonged bouts of winning or losing male-male contests on plasticity in sexually selected traits

Harrison¹,

Vega‐Trejo²,

Jennions³

2021

Preprint

Self Cite

View full text Add to dashboard Cite

The outcomes of fights often affect the fitness of males by determining their access to mates. ‘Winner-loser’ effects, where winners often win their next contest, but losers tend to lose, can therefore influence how males allocate resources towards traits under pre- and post-copulatory sexual selection. We experimentally manipulated the winning/losing experiences of size-matched male Gambusia holbrooki for either a day, a week or three weeks to test whether prior winning/losing experiences differentially affect the plasticity of male investment into either mating effort (pre-copulatory) or ejaculates (post-copulatory). Winners had better pre-copulatory outcomes than losers for three of the four traits we measured: number of mating attempts, number of successful attempts, and time spent with the female. Winners also produced faster sperm than losers, but there was no difference in total sperm counts. Interestingly, absolute male size, an important predictor of fighting success, mediated the effect of winning or losing on how long males then spent near a female. Smaller winners spent more time with the female than did larger winners, suggesting that how males respond to prior social experiences is size-dependent. We discuss the general importance of controlling for inherent male condition when comparing male investment into condition-dependent traits.

show abstract

Section: Plasticity and Body Sizesupporting

confidence: 47%

Section: Experimental Design: Making Winners and Losersmentioning

confidence: 99%

The effect of brief or prolonged bouts of winning or losing male-male contests on plasticity in sexually selected traits

Harrison¹,

Vega‐Trejo²,

Jennions³

2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Either way, the lack of increased investment in ejaculates and copulation duration when competing with another male indicates that if changes in mating behavior result from differences in the social environment, it is not in the direction we predicted, and future studies would benefit from looking at male mating behavior in a more realistic context (i.e., in the presence versus absence of competitors) and over a longer time frame. This approach has recently been taken in Eastern mosquitofish (Spagopoulou, Vega‐trejo, Head, & Jennions, 2020).…”

Section: Discussionmentioning

confidence: 99%

The effects of competition on fitness depend on the sex of both competitors

Iglesias‐Carrasco

Brookes

Kruuk

et al. 2020

Ecology and Evolution

Self Cite

View full text Add to dashboard Cite

In intraspecific competition, the sex of competing individuals is likely to be important in determining the outcome of competitive interactions and the way exposure to conspecifics during development influences adult fitness traits. Previous studies have explored differences between males and females in their response to intraspecific competition. However, few have tested how the sex of the competitors, or any interactions between focal and competitor sex, influences the nature and intensity of competition. We set up larval seed beetles Callosobruchus maculatus to develop either alone or in the presence of a male or female competitor and measured a suite of traits: development time, emergence weight; male ejaculate mass, copulation duration, and lifespan; and female lifetime fecundity, offspring egg-adult survival, and lifespan. We found effects of competition and competitor sex on the development time and emergence weight of both males and females, and also of an interaction between focal and competitor sex: Females emerged lighter when competing with another female, while males did not. There was little effect of larval competition on male and female adult fitness traits, with the exception of the effect of a female competitor on a focal female's offspring survival rate. Our results highlight the importance of directly measuring the effects of competition on fitness traits, rather than distant proxies for fitness, and suggest that competition with the sex with the greater resource requirements (here females) might play a role in driving trait evolution. We also found that male-male competition during development resulted in shorter copulation times than male-female competition, a result that remained when controlling for the weight of competitors. Although it is difficult to definitively tease apart the effects of social environment and access to resources, this result suggests that something about the sex of competitors other than their size is driving this pattern.

show abstract

“…Males allocate more sperm when exposed to a single competitor (risk), but do not reduce sperm allocation when exposed to multiple competitors (intensity; reviewed by [6,7]). When assessing sperm swimming speed, poeciliids either show increases [49], no response [50] or decreases [51] when exposed to social conditions indicating sperm competition risk, and no response to sperm competition intensity [50]. Responses in sperm swimming speed to sperm competition risk can differ between male mating roles in species with alternative reproductive tactics (i.e.…”

Section: (B) Sperm Number and Quality In Internally Fertilizing Bony Fishesmentioning

confidence: 99%

Sperm competition and fertilization mode in fishes

Fitzpatrick

2020

Phil. Trans. R. Soc. B

View full text Add to dashboard Cite

Sperm competition is a powerful selective force that has shaped sexual traits throughout animal evolution. Yet, how fertilization mode (i.e. external versus internal fertilization) influences the scope and potential for sperm competition to act on ejaculates remains unclear. Here, I examine how fertilization mode shapes ejaculatory responses to sperm competition in fishes, a diverse group that constitute the majority of vertebrate biological diversity. Fishes are an ideal group for this examination because they exhibit a wide range of reproductive behaviours and an unparalleled number of transitions in fertilization mode compared to any other vertebrate group. Drawing on data from cartilaginous and bony fishes, I first show that rates of multiple paternity are higher in internally than externally fertilizing fishes, contrary to the prevailing expectation. I then summarize how sperm competition acts on sperm number and quality in internally and externally fertilizing fishes, highlighting where theoretical predictions differ between these groups. Differences in how ejaculates respond to sperm competition between fertilization modes are most apparent when considering sperm size and swimming performance. Clarifying how fertilization mode influences evolutionary responses in ejaculates will inform our understanding of ejaculate evolution across the animal tree of life. This article is part of the theme issue ‘Fifty years of sperm competition’.

show abstract

Shifts in Reproductive Investment in Response to Competitors Lower Male Reproductive Success

Cited by 11 publications

References 94 publications

The effect of brief or prolonged bouts of winning or losing male-male contests on plasticity in sexually selected traits

The effect of brief or prolonged bouts of winning or losing male-male contests on plasticity in sexually selected traits

The effects of competition on fitness depend on the sex of both competitors

Sperm competition and fertilization mode in fishes

Contact Info

Product

Resources

About