scholarly journals Benefits of size dimorphism and copulatory silk wrapping in the sexually cannibalistic nursery web spider, Pisaurina mira

2016 ◽  
Vol 12 (2) ◽  
pp. 20150957 ◽  
Author(s):  
Alissa G. Anderson ◽  
Eileen A. Hebets
Keyword(s):  
Body Size ◽  
Relative Size ◽  
Male Reproductive Success ◽  
Male Fitness ◽  
Male Size ◽  
Treatment Groups ◽  
Web Spider ◽  
Sexually Selected Traits ◽  
Mate Acquisition ◽  
Selected Traits

In sexually cannibalistic animals, male fitness is influenced not only by successful mate acquisition and egg fertilization, but also by avoiding being eaten. In the cannibalistic nursery web spider, Pisaurina mira , the legs of mature males are longer in relation to their body size than those of females, and males use these legs to aid in wrapping a female's legs with silk prior to and during copulation. We hypothesized that elongated male legs and silk wrapping provide benefits to males, in part through a reduced likelihood of sexual cannibalism. To test this, we paired females of random size with males from one of two treatment groups—those capable of silk wrapping versus those incapable of silk wrapping. We found that males with relatively longer legs and larger body size were more likely to mate and were less likely to be cannibalized prior to copulation. Regardless of relative size, males capable of silk wrapping were less likely to be cannibalized during or following copulation and had more opportunities for sperm transfer (i.e. pedipalpal insertions). Our results suggest that male size and copulatory silk wrapping are sexually selected traits benefiting male reproductive success.

scholarly journals Male size mediates plastic response to winner-loser effects for some sexually selected traits

2021 ◽  
Author(s):  
Lauren Maree Harrison ◽  
Regina Vega-Trejo ◽  
Michael D Jennions
Keyword(s):  
Gambusia Holbrooki ◽  
Plastic Response ◽  
Male Size ◽  
Male Investment ◽  
Size Dependent ◽  
Sexually Selected Traits ◽  
General Importance ◽  
Sperm Counts ◽  
Male Condition ◽  
Selected Traits

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.

scholarly journals Cancer susceptibility and reproductive trade-offs: a model of the evolution of cancer defences

2015 ◽  
Vol 370 (1673) ◽  
pp. 20140220 ◽  
Author(s):  
Amy M. Boddy ◽  
Hanna Kokko ◽  
Felix Breden ◽  
Gerald S. Wilkinson ◽  
C. Athena Aktipis
Keyword(s):  
Cell Proliferation ◽  
Body Size ◽  
Cancer Susceptibility ◽  
Large Body ◽  
Large Body Size ◽  
Trade Off ◽  
Extrinsic Mortality ◽  
Sexually Selected Traits ◽  
Trade Offs ◽  
Selected Traits

The factors influencing cancer susceptibility and why it varies across species are major open questions in the field of cancer biology. One underexplored source of variation in cancer susceptibility may arise from trade-offs between reproductive competitiveness (e.g. sexually selected traits, earlier reproduction and higher fertility) and cancer defence. We build a model that contrasts the probabilistic onset of cancer with other, extrinsic causes of mortality and use it to predict that intense reproductive competition will lower cancer defences and increase cancer incidence. We explore the trade-off between cancer defences and intraspecific competition across different extrinsic mortality conditions and different levels of trade-off intensity, and find the largest effect of competition on cancer in species where low extrinsic mortality combines with strong trade-offs. In such species, selection to delay cancer and selection to outcompete conspecifics are both strong, and the latter conflicts with the former. We discuss evidence for the assumed trade-off between reproductive competitiveness and cancer susceptibility. Sexually selected traits such as ornaments or large body size require high levels of cell proliferation and appear to be associated with greater cancer susceptibility. Similar associations exist for female traits such as continuous egg-laying in domestic hens and earlier reproductive maturity. Trade-offs between reproduction and cancer defences may be instantiated by a variety of mechanisms, including higher levels of growth factors and hormones, less efficient cell-cycle control and less DNA repair, or simply a larger number of cell divisions (relevant when reproductive success requires large body size or rapid reproductive cycles). These mechanisms can affect intra- and interspecific variation in cancer susceptibility arising from rapid cell proliferation during reproductive maturation, intrasexual competition and reproduction.

scholarly journals Why the Static Allometry of Sexually-Selected Traits Is So Variable: The Importance of Function

2019 ◽  
Vol 59 (5) ◽  
pp. 1290-1302 ◽  
Author(s):  
Rafael Lucas Rodríguez ◽  
William G Eberhard
Keyword(s):  
Body Size ◽  
Body Part ◽  
Positive Allometry ◽  
Large Structures ◽  
Sexually Selected Traits ◽  
Body Sizes ◽  
Selected Traits ◽  
Courtship Signals ◽  
Aggressive Signals ◽  
Static Allometry

AbstractSexually-selected traits often show positive static allometry, with large individuals bearing disproportionately large structures. But many other sexually-selected traits show isometry or even negative allometry, with trait size varying relatively little with body size. We recently proposed that the functions of these traits (as aggressive signals, weapons, courtship signals, and contact courtship devices) determine their allometries. Positive allometry is generally favored for aggressive signals because aggressive signals are selected to emphasize body size (and thus fighting prowess). In contrast, the biomechanics of force application in weapons only sometimes select for positive allometry; the content of courtship signals is even less often related to body size; and contact courtship devices are selected to be relatively invariant across body sizes. Here we summarize the arguments in favor of this “functional allometry” hypothesis and expand a comparative test of its predictions. Our results indicate that sexual traits have the allometric slopes predicted by our hypothesis, regardless of which body part bears the structure.

scholarly journals Developmental stress increases reproductive success in male zebra finches

2014 ◽  
Vol 281 (1795) ◽  
pp. 20141266 ◽  
Author(s):  
Ondi L. Crino ◽  
Colin T. Prather ◽  
Stephanie C. Driscoll ◽  
Jeffrey M. Good ◽  
Creagh W. Breuner
Keyword(s):  
Reproductive Success ◽  
Parental Care ◽  
Reproductive Investment ◽  
Common Garden ◽  
Poor Quality ◽  
Male Reproductive Success ◽  
Developmental Stress ◽  
Reproductive Tactics ◽  
Sexually Selected Traits ◽  
Selected Traits

There is increasing evidence that exposure to stress during development can have sustained effects on animal phenotype and performance across life-history stages. For example, developmental stress has been shown to decrease the quality of sexually selected traits (e.g. bird song), and therefore is thought to decrease reproductive success. However, animals exposed to developmental stress may compensate for poor quality sexually selected traits by pursuing alternative reproductive tactics. Here, we examine the effects of developmental stress on adult male reproductive investment and success in the zebra finch ( Taeniopygia guttata ). We tested the hypothesis that males exposed to developmental stress sire fewer offspring through extra-pair copulations (EPCs), but invest more in parental care. To test this hypothesis, we fed nestlings corticosterone (CORT; the dominant avian stress hormone) during the nestling period and measured their adult reproductive success using common garden breeding experiments. We found that nestlings reared by CORT-fed fathers received more parental care compared with nestlings reared by control fathers. Consequently, males fed CORT during development reared nestlings in better condition compared with control males. Contrary to the prediction that developmental stress decreases male reproductive success, we found that CORT-fed males also sired more offspring and were less likely to rear non-genetic offspring compared with control males, and thus had greater overall reproductive success. These data are the first to demonstrate that developmental stress can have a positive effect on fitness via changes in reproductive success and provide support for an adaptive role of developmental stress in shaping animal phenotype.

scholarly journals The growth factor BMP11 is required for the development and evolution of a male exaggerated weapon and its associated fighting behavior in a water strider

PLoS Biology ◽  
2021 ◽  
Vol 19 (5) ◽  
pp. e3001157
Author(s):  
William Toubiana ◽  
David Armisén ◽  
Séverine Viala ◽  
Amélie Decaras ◽  
Abderrahman Khila
Keyword(s):  
Body Size ◽  
Growth Factor ◽  
The Body ◽  
Specific Factor ◽  
Male Body ◽  
Water Strider ◽  
Fighting Behavior ◽  
Sexually Selected Traits ◽  
Morphogenetic Protein ◽  
Selected Traits

Exaggerated sexually selected traits, often carried by males, are characterized by the evolution of hyperallometry, resulting in their disproportionate growth relative to the rest of the body among individuals of the same population. While the evolution of allometry has attracted much attention for centuries, our understanding of the developmental genetic mechanisms underlying its emergence remains fragmented. Here we conduct comparative transcriptomics of the legs followed by an RNA interference (RNAi) screen to identify genes that play a role in the hyperallometric growth of the third legs in the males of the water strider Microvelia longipes. We demonstrate that a broadly expressed growth factor, Bone Morphogenetic Protein 11 (BMP11, also known as Growth Differentiation Factor 11), regulates leg allometries through increasing the allometric slope and mean body size in males. In contrast, BMP11 RNAi reduced mean body size but did not affect slope either in the females of M. longipes or in the males and females of other closely related Microvelia species. Furthermore, our data show that a tissue-specific factor, Ultrabithorax (Ubx), increases intercept without affecting mean body size. This indicates a genetic correlation between mean body size and variation in allometric slope, but not intercept. Strikingly, males treated with BMP11 RNAi exhibited a severe reduction in fighting frequency compared to both controls and Ubx RNAi-treated males. Therefore, male body size, the exaggerated weapon, and the intense fighting behavior associated with it are genetically correlated in M. longipes. Our results support a possible role of pleiotropy in the evolution of allometric slope.

scholarly journals Are sexually selected traits affected by a poor environment early in life?

2016 ◽  
Author(s):  
Regina Vega-Trejo ◽  
Michael D. Jennions ◽  
Megan L. Head
Keyword(s):  
Body Size ◽  
Fitness Costs ◽  
Rate Dependent ◽  
Sexually Selected Traits ◽  
Catching Up ◽  
Limited Food ◽  
Additional Costs ◽  
Nutritional Environment ◽  
Selected Traits

AbstractConditions experienced early in life can affect key life-history traits. Individuals that experience a poor nutritional environment early in life can reduce potential costs by delaying sexual maturation. The direct costs of delaying maturation are well known (i.e. delayed onset of breeding), but individuals can also face additional costs as adults. Some of these ‘hidden costs’ accrue due to cryptic morphological and physiological changes. In mosquitofish (Gambusia holbrooki), males with limited food intake early in life delay maturation to eventually reach a similar adult body size to their well-fed counterparts (‘catch-up growth’). Here we tested whether a poor diet early in life incurs hidden costs due to reduced expression of sexually selected male traits (genital size and ejaculate traits). We found that diet early in life significantly influenced sperm reserves and replenishment rate due to age and development-rate dependent effects. Although catching-up in body size ameliorates some of the costs of a poor start in life for males, our findings suggest that long-term fitness costs might arise because of sexually selection against these males. Our results highlight that fitness costs of a poor start in life can extend into adulthood.

scholarly journals The allometry between secondary sexual traits and body size is nonlinear among cervids

2014 ◽  
Vol 10 (3) ◽  
pp. 20130869 ◽  
Author(s):  
J. F. Lemaître ◽  
C. Vanpé ◽  
F. Plard ◽  
J. M. Gaillard
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Life History Theory ◽  
Male Body ◽  
Allometric Relationships ◽  
Secondary Sexual Traits ◽  
Sexually Selected Traits ◽  
Large Size ◽  
Antler Size ◽  
Selected Traits

Allometric relationships between sexually selected traits and body size have been extensively studied in recent decades. While sexually selected traits generally display positive allometry, a few recent reports have suggested that allometric relationships are not always linear. In male cervids, having both long antlers and large size provides benefits in terms of increased mating success. However, such attributes are costly to grow and maintain, and these costs might constrain antler length from increasing at the same rate as body mass in larger species if the quantity of energy that males can extract from their environment is limiting. We tested for possible nonlinearity in the relationship between antler size and body mass (on a log–log scale) among 31 cervids and found clear deviation from linearity in the allometry of antler length. Antler length increased linearly until a male body mass threshold at approximately 110 kg. Beyond this threshold, antler length did not change with increasing mass. We discuss this evidence of nonlinear allometry in the light of life-history theory and stress the importance of testing for nonlinearity when studying allometric relationships.

Copulation duration and probability of insemination in Anthocoris whitei (Hemiptera: Anthocoridae) as a function of male body size

2001 ◽  
Vol 133 (1) ◽  
pp. 109-117 ◽  
Author(s):  
David R. Horton ◽  
Tamera M. Lewis ◽  
Tonya Hinojosa
Keyword(s):  
Body Size ◽  
Relative Size ◽  
Copulation Duration ◽  
Male Body ◽  
Male Size ◽  
Male And Female ◽  
Female Body Size ◽  
Duration Of Copulation ◽  
Two Temperatures ◽  
Increasing Temperature

AbstractThe influence of male and female body size on copulation duration and probability of insemination was determined for Anthocoris whitei Reuter allowed to mate at two temperatures. Copulation duration decreased significantly with increasing male length or increasing relative size (male length divided by female length). Female length had no effect on copulation duration. We interrupted copulation at 20 or 40 min at both 25 and 15 °C to determine the interacting effects of male size, temperature, and copulation duration on probability of insemination. Insemination probabilities increased with increasing male size, increasing temperature, and increased duration of copulation. Large males were more successful than small males at inseminating females at cool temperatures and for severely shortened copulations. Results are consistent with the hypothesis that males of this species experience physical difficulties either in achieving intromission or in forcing sperm through the aedeagus, and that larger body size in males lessens these difficulties.

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