Faster Lizards Sire More Offspring: Sexual Selection on Whole-Animal Performance

Husak, Jerry F.; Fox, Stanley F.; Lovern, Matthew B.; Bussche, Ronald A. Van Den

doi:10.1111/j.0014-3820.2006.tb01849.x

Cited by 225 publications

(159 citation statements)

References 75 publications

(94 reference statements)

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“…Given the close relationship between head morphology and bite performance observed across sexes, we conclude that the form-function association in lizards is tightly linked to the observed sexual dimorphism in both aspects, with sexual selection potentially being the underlying evolutionary force, as has been proven for other lizard groups (Husak et al 2006a;Lailvaux and Irschick 2006). However, such a hypothesis can only be definitely confirmed by directly examining the reproductive fitness of male individuals and associating it to both head morphology and bite performance (Lappin and Husak 2005;Irschick et al 2007), as has been done for the form-locomotor performance complex (Husak et al 2006b;Husak and Fox 2008). manuscript.…”

Section: Discussionmentioning

confidence: 60%

Relationships between head morphology, bite performance and ecology in two species of Podarcis wall lizards

et al. 2011

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Understanding the relationship between form and function is central to our comprehension of how phenotypic diversity evolves. Traits involved in multiple activities, such as social interactions and ecological resource use, are under the influence of different evolutionary forces potentially acting in opposite directions. Such systems provide the opportunity of understanding how potential constraints on morphological variation may influence whole-organism performance. In this study we examined morphology and bite performance in two closely related species of Podarcis wall lizards with divergent microhabitat preferences, to investigate how natural and sexual selection interact to shape the evolution of head traits. Our results show that although head morphology is markedly different between species and sexes, only sexes differ in bite force, indicating that the ecological differentiation between species is reflected in their morphology but does not constrain performance. Rather, the modification of the relative size of head components between species and a shift in the form-function relationship provide a potential explanation of how equal performance is attained by different morphological configurations. Geometric morphometrics provide a clear, biomechanically meaningful image of how this is achieved and show a bisexual pattern of head shape-bite force association in both species. This, together with a strong allometry of head size on body size and head shape on head size, provides indirect morphological evidence for the importance of sexual selection in shaping morphological and functional patterns. Finally, our findings suggest that the differences observed between species and sexes in head traits and bite performance are not reflected in their dietary ecology, implying that if trophic niche segregation between groups occurs, the reasons behind it are not primarily related to head morphology and functional variation.

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Section: Discussionmentioning

confidence: 60%

Relationships between head morphology, bite performance and ecology in two species of Podarcis wall lizards

et al. 2011

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“…Faster individuals have greater success at escaping predators, catching prey, and also may have more beneficial social interactions and ultimately more mating opportunities (Garland et al 1990;Husak 2006;Husak et al 2006;Jayne and Bennett 1990), whereas larger offspring that grow faster have a greater chance of survival to maturity (Ferguson and Fox 1984; but see Congdon et al 1999;Warner and Shine 2007). Additionally, individual animals vary consistently in their behavior, including their readiness to take risks (Sih et al 2004), and these behavioral differences can have a large influence on survival.…”

Section: Introductionmentioning

confidence: 99%

Effects of early postnatal environment on phenotype and survival of a lizard

2011

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Nutritional and thermal regimes experienced early in life can strongly influence offspring quality and ultimately adult life histories, especially in ectotherms. However, the importance of the interaction between diet and temperature during postnatal development and the effect on offspring quality are unknown. We compared offspring quality (size, shape, speed, behavior, and survival) of juvenile McCann's skinks (Oligosoma maccanni) housed outdoors under variable thermal conditions (under shelter, but exposed to daily and seasonal variations in light and temperature) with those housed indoors under more stable thermal conditions (controlled temperatures providing 30-40% more basking opportunity) and with a control group (open field conditions). For those caged in captivity (indoors and outdoors), we also compared outcomes between those fed a restricted diet and those fed ad libitum. By comparing individuals raised under different environmental regimes, we aimed to determine whether direct effects of temperature or indirect effects of food supply are more important for offspring quality. Individuals provided with food ad libitum grew faster, and attained larger sizes than those raised on a restricted diet or in the field. Activity rates were higher in individuals exposed to stable rather than variable thermal conditions. Survival post release in the field was highest for larger neonates, and lowest in individuals raised under stable thermal conditions and a restricted diet. We found little evidence for effects of an interaction between feeding and thermal regimes on most factors measured. However, the conditions experienced by young animals (especially diet) do influence important traits for population persistence, such as survival, and may influence key reproductive parameters (e.g., age and size at maturity), which could have implications for conservation management. Further research, including the ultimate influence of early environmental conditions on fecundity and life expectancy, is urgently needed.

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“…For example, larger body size may enhance survival rates in some populations but not in others (Sinervo et al 1992;Heath and Blouw 1998), in some years but not others (Ferguson and Fox 1984;Sinervo et al 1992;Olsson and Madsen 2001;Warner and Andrews 2002), and in oVspring of one sex but not the other (Langkilde and Shine 2005). In other cases, Wtness is not linked with body size at all (Congdon et al 1999;Husak et al 2006;Dibattista et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Fitness of juvenile lizards depends on seasonal timing of hatching, not offspring body size

2007

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To understand how selection shapes life-history traits, we need information on the manner in which offspring phenotypes influence fitness. Life-history allocation models typically assume that "bigger offspring are better", but field data paint a more complex picture: larger offspring size sometimes enhances fitness, and sometimes not. Additionally, higher survival and faster growth of larger offspring might be due to indirect maternal effects (e.g., mothers allocate hormones or nutrients differently to different-sized eggs), and not to offspring size per se. Alternative factors, such as seasonal timing of hatching, may be more important. We examined these issues using 419 eggs from captive jacky dragon lizards (Amphibolurus muricatus). The mothers were maintained under standardized conditions to minimize variance in thermal and nutritional history, and the eggs were incubated under controlled conditions to minimize variance in offspring phenotypes due to incubation temperature and moisture. We reduced the size of half the eggs (and, thus, the size of the resultant hatchlings) from each clutch by yolk extraction. The hatchlings were marked and released at a field site over a 3-month period, with regular recapture surveys to measure growth and survival under natural conditions. Growth rates and survival were strongly enhanced by early-season hatching, but were not affected by hatchling body size.

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Faster Lizards Sire More Offspring: Sexual Selection on Whole-Animal Performance

Cited by 225 publications

References 75 publications

Relationships between head morphology, bite performance and ecology in two species of Podarcis wall lizards

Relationships between head morphology, bite performance and ecology in two species of Podarcis wall lizards

Effects of early postnatal environment on phenotype and survival of a lizard

Fitness of juvenile lizards depends on seasonal timing of hatching, not offspring body size

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