Effects of individual variation in age and size at metamorphosis on growth and survivorship of southern toad (<i>Bufo terrestris</i>) metamorphs

Beck, Christopher W.; Congdon, Justin D.

doi:10.1139/z99-041

Cited by 40 publications

(37 citation statements)

References 20 publications

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“…A possible explanation for this is plasticity in growth rates where small individuals have elevated growth rates (Beck andCongdon 1999, Boone 2005). This would then lead to similar performance of individuals with different starting conditions (i.e., date of and size at metamorphosis).…”

Section: Discussionmentioning

confidence: 99%

From metamorphosis to maturity in complex life cycles: equal performance of different juvenile life history pathways

Schmidt

Hödl

Schaub

2012

Ecology

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Performance in one stage of a complex life cycle may affect performance in the subsequent stage. Animals that start a new stage at a smaller size than conspecifics may either always remain smaller or they may be able to "catch up" through plasticity, usually elevated growth rates. We study how size at and date of metamorphosis affected subsequent performance in the terrestrial juvenile stage and lifetime fitness of spadefoot toads (Pelobates fuscus). We analyzed capture-recapture data of >3000 individuals sampled during nine years with mark-recapture models to estimate first-year juvenile survival probabilities and age-specific first-time breeding probabilities of toads, followed by model selection to assess whether these probabilities were correlated with size at and date of metamorphosis. Males attained maturity after two years, whereas females reached maturity 2-4 years after metamorphosis. Age at maturity was weakly correlated with metamorphic traits. In both sexes, first-year juvenile survival depended positively on date of metamorphosis and, in males, also negatively on size at metamorphosis. In males, toads that metamorphosed early at a small size had the highest probability to reach maturity. However, because very few toadlets metamorphosed early, the vast majority of male metamorphs had a very similar probability to reach maturity. A matrix projection model constructed for females showed that different juvenile life history pathways resulted in similar lifetime fitness. We found that the effects of date of and size at metamorphosis on different juvenile traits cancelled each other out such that toads that were small or large at metamorphosis had equal performance. Because the costs and benefits of juvenile life history pathways may also depend on population fluctuations, ample phenotypic variation in life history traits may be maintained. Abstract. Performance in one stage of a complex life cycle may affect performance in the subsequent stage. Animals that start a new stage at a smaller size than conspecifics may either always remain smaller or they may be able to ''catch up'' through plasticity, usually elevated growth rates. We study how size at and date of metamorphosis affected subsequent performance in the terrestrial juvenile stage and lifetime fitness of spadefoot toads (Pelobates fuscus). We analyzed capture-recapture data of .3000 individuals sampled during nine years with mark-recapture models to estimate first-year juvenile survival probabilities and agespecific first-time breeding probabilities of toads, followed by model selection to assess whether these probabilities were correlated with size at and date of metamorphosis. Males attained maturity after two years, whereas females reached maturity 2-4 years after metamorphosis. Age at maturity was weakly correlated with metamorphic traits. In both sexes, first-year juvenile survival depended positively on date of metamorphosis and, in males, also negatively on size at metamorphosis. In males, toads that metamorphosed early at a sma...

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Section: Discussionmentioning

confidence: 99%

From metamorphosis to maturity in complex life cycles: equal performance of different juvenile life history pathways

Schmidt

Hödl

Schaub

2012

Ecology

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“…Strong empirical evidence for the positive relationship between size at metamorphosis and fitness for larval amphibians (Semlitsch et al, 1988;Beck and Congdon, 1999) suggests that selection will act to increase size at the termination of the larval growth trajectory, and if there is positive selection for size at all other ages, then evolutionary responses should be strong and in the direction of selection. If, however, selection is positive at some ages and negative at others, then evolutionary responses should be relatively weak and in a direction oblique to the direction of selection.…”

Section: Discussionmentioning

confidence: 99%

“…Both timing and size at metamorphosis are important life history traits in pondbreeding amphibians that can have substantial fitness consequences. Size at metamorphosis can influence juvenile survival, size at first reproduction, and age at first reproduction (Semlitsch et al, 1988;Beck and Congdon, 1999), all of which are important fitness components.…”

Section: Introductionmentioning

confidence: 99%

Genetic covariance structure of growth in the salamander Ambystoma macrodactylum

Ragland

Carter

2004

Heredity

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“…The combination of metamorph traits that maximizes adult recruitment ultimately depends upon the relative importance of those traits. Some studies of amphibians suggest that development time and/or size at metamorphosis are relatively unimportant for subsequent performance (Beck andCongdon 1999, Boone 2005). If only the number of individuals surviving to metamorphosis matters for B. nebulifer, then at low densities, high hatching synchrony will result in the highest adult recruitment, and at high densities, hatching synchrony might not matter.…”

Section: Implications Of Phenological Synchrony For Population Dynamicsmentioning

confidence: 99%

“…If large metamorphs maintain their size advantage, they can then achieve sexual maturity faster and have higher reproductive fitness. Less is known about the consequences of variation in development time for subsequent survival and growth of amphibians, because they are usually only evaluated shortly after metamorphosis (Beck and Congdon 1999). Many organisms exhibit complex life cycles (e.g., amphibians, insects, fishes, many marine invertebrates), and their life-history events are usually seasonal.…”

Section: Implications Of Phenological Synchrony For Population Dynamicsmentioning

confidence: 99%

Phenological synchronization drives demographic rates of populations

Rasmussen

Rudolf

2015

Ecology

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Abstract. Phenology is increasingly recognized as an important factor structuring communities because it determines when and at what life stage organisms interact. Previous work indicates that changes in first or mean timing of a phenological event can affect populations and communities, but little is known about the consequences of changes in the distribution (e.g., synchrony) of a phenological event. We conducted an experiment using an anuran study system to determine how synchrony of reproduction and egg hatching affects offspring performance, whether the effects are density dependent, and how hatching synchrony influences the synchrony of a subsequent phenological event (metamorphosis). Changes in hatching synchrony altered survival, development rates, and body size at metamorphosis, which can affect post-metamorphosis performance. The degree of synchrony at hatching also affected the degree of synchrony at metamorphosis, indicating that timing of one stage can carry over to affect that of later ones. Importantly, these effects were all density dependent, likely because decreasing hatching synchrony switched intraspecific interactions from scramble to contest competition. This study demonstrates that phenological synchrony has important consequences for ecological interactions and population dynamics, emphasizing the need to develop a comprehensive understanding of how shifts in phenological distributions affect communities.

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Effects of individual variation in age and size at metamorphosis on growth and survivorship of southern toad (Bufo terrestris) metamorphs

Cited by 40 publications

References 20 publications

From metamorphosis to maturity in complex life cycles: equal performance of different juvenile life history pathways

From metamorphosis to maturity in complex life cycles: equal performance of different juvenile life history pathways

Genetic covariance structure of growth in the salamander Ambystoma macrodactylum

Phenological synchronization drives demographic rates of populations

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