Capital versus Income Breeding: An Ectothermic Perspective

Bonnet, Xavier; Bradshaw, Don; Shine, Richard

doi:10.2307/3546846

Cited by 305 publications

(337 citation statements)

References 91 publications

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“…Another important difference within vertebrates is the mode of temperature regulation. Indeed, ectotherms can store energy more efficiently than endotherms like birds, and thus rely more often on stored resources to fuel reproduction (capital versus income breeders) [82]. Such different reproductive strategies may induce different reproductive costs.…”

Section: Discussionmentioning

confidence: 99%

Reproductive costs in terrestrial male vertebrates: insights from bird studies

2016

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Reproduction requires resources that cannot be allocated to other functions resulting in direct reproductive costs (i.e. trade-offs between current reproduction and subsequent survival/reproduction). In wild vertebrates, direct reproductive costs have been widely described in females, but their occurrence in males remains to be explored. To fill this gap, we gathered 53 studies on 48 species testing direct reproductive costs in male vertebrates. We found a trade-off between current reproduction and subsequent performances in 29% of the species and in every clade. As 73% of the studied species are birds, we focused on that clade to investigate whether such trade-offs are associated with (i) levels of paternal care, (ii) polygyny or (iii) pace of life. More precisely for this third question, it is expected that fast species (i.e. short lifespan, early maturity, high fecundity) pay a cost in terms of survival, whereas slow species (with opposite characteristics) do so in terms of fecundity. Our findings tend to support this hypothesis. Finally, we pointed out the potential confounding effects that should be accounted for when investigating reproductive costs in males and strongly encourage the investigation of such costs in more clades to understand to what extent our results are relevant for other vertebrates.

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Section: Discussionmentioning

confidence: 99%

Reproductive costs in terrestrial male vertebrates: insights from bird studies

2016

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“…Thus, some of the captured snakes were emaciated, some were intermediate in condition, and some had large body reserves. Because a large sample (122 asp vipers: 85 females and 37 males) of accidentally killed asp vipers has been previously autopsied (see Bonnet, 1996;Bonnet et al, 1998a, for details of the autopsies), and because snakes exhibit a highly simplified morphology (Bonnet et al, 1998a), we were able to estimate the mass of the body reserves of the snakes involved in the present experiment. The mass of the major body reserves, fat bodies, liver, and skeletal muscles was weighed to the nearest 0.1 g. External morphology of snakes is easily characterized by their body length and their body mass.…”

Section: Experimental Designmentioning

confidence: 99%

Fat Is Sexy for Females but Not Males: The Influence of Body Reserves on Reproduction in Snakes (Vipera aspis)

Aubret

Bonnet

Shine

et al. 2002

Hormones and Behavior

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Reproduction is energetically expensive for both sexes, but the magnitude of expenditure and its relationship to reproductive success differ fundamentally between males and females. Males allocate relatively little to gamete production and, thus, can reproduce successfully with only minor energy investment. In contrast, females of many species experience high fecundity-independent costs of reproduction (such as migration to nesting sites), so they need to amass substantial energy reserves before initiating reproductive activity. Thus, we expect that the relationship between energy reserves and the intensity of reproductive behavior involves a threshold effect in females, but a gradual (or no) effect in males. We tested this prediction using captive vipers (Vipera aspis), dividing both males and females into groups of high versus low body condition. Snakes from each group were placed together and observed for reproductive behavior; sex-steroid levels were also measured. As predicted, females in below-average body condition had very low estradiol levels and did not show sexual receptivity, whereas males of all body condition indices had significant testosterone levels and displayed active courtship. Testosterone levels and courtship intensity increased gradually (i.e., no step function) with body condition in males, but high estradiol levels and sexual receptivity were seen only in females with body reserves above a critical threshold. The energetics of reproduction has been a central theme in the ecological study of life history variation (Hirshfield and Tinkle, 1975;Morris, 1987Morris, , 1992Winkler and Wallin, 1987;Stearns, 1992; Monaghan and Nager, 1997), and more recently this topic has become an important focus in behavioral endocrinology (Cherel, Mauget, Lacroix, and Gilles, 1994;Bronson, 1998). It is obvious that organisms cannot reproduce in the total absence of energy reserves (Frish, 1978;Frish and McArthur, 1974), but the relationship between the amount of energy reserves and reproductive output (or effort) is complex and varies among species. In some species there is a linear relationship between energy reserves and reproductive output. In others there appears to be no discernible relationship (e.g., if clutch and offspring sizes are fixed) or a complex nonlinear relationship between the two variables. For example, many organisms are "capital breeders" that rely on previously gathered energy stored in the form of body reserves (i.e., fat bodies, proteins) rather than on current energy intake to fuel the energetically costly process of reproduction (Drent and Daan, 1980;Jö nsson, 1997; Bonnet, Bradshaw, and Shine, 1998). In such species, life history theory predicts that a threshold level of energy reserves is necessary for a reproductive cycle to begin, rather than a linear relationship in which an increment in energy availability adds an increment in reproductive output (Schaffer, 1974;Bull and Shine, 1979;Stearns, 1992). Several empirical studies provide evidence for nonlinear relationships between...

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“…Because many macrostomate snakes rely on infrequent ingestion of large prey items (Greene 1983), food intake may be low relative to maternal body size. Thus, female reproduction is infrequent, and is often fuelled by long-term energy stores (capital breeding; Bonnet et al 1998). The critical importance of energy has also favoured adaptations to reduce energy expenditure, including sedentary behaviour, low basal metabolic rates, and the ability to downregulate organs (such as the digestive tract) during quiescent periods (Pough 1980;Secor & Diamond 1995).…”

Section: (F ) Overview For Femalesmentioning

confidence: 99%

Reproductive strategies in snakes

Shine

2003

Proc. R. Soc. Lond. B

267

199

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Snakes of both sexes display remarkable flexibility and diversity in their reproductive tactics. Many features of reproduction in female snakes (such as reproductive mode and frequency, seasonality and multiple mating) allow flexible maternal control. For example, females can manipulate not only the genotypes of their offspring (through mate choice or enhanced sperm competition) but also the phenotypes of their offspring (through allocation 'decisions', behavioural and physiological thermoregulation, and nest-site selection). Reliance on stored energy ('capital') to fuel breeding results in low frequencies of female reproduction and, in extreme cases, semelparity. A sophisticated vomeronasal system not only allows male snakes to locate reproductive females by following scent trails, but also facilitates pheromonally mediated mate choice by males. Male-male rivalry takes diverse forms, including female mimicry and mate guarding; combat bouts impose strong selection for large body size in males of some species. Intraspecific (geographical) variation and phenotypic plasticity in a wide array of reproductive traits (offspring size and number; reproductive frequency; incidence of multiple mating; male tactics such as mate guarding and combat; mate choice criteria) provide exceptional opportunities for future studies.

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Capital versus Income Breeding: An Ectothermic Perspective

Cited by 305 publications

References 91 publications

Reproductive costs in terrestrial male vertebrates: insights from bird studies

Reproductive costs in terrestrial male vertebrates: insights from bird studies

Fat Is Sexy for Females but Not Males: The Influence of Body Reserves on Reproduction in Snakes (Vipera aspis)

Reproductive strategies in snakes

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