Determinants of size at metamorphosis in an endangered amphibian and their projected effects on population stability

Christopher Searcy, Helen Snaas, H. Bradley Shaffer

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Roughly 80% of animal species have complex life cycles spanning a major habitat shift, and delayed life history effects play an important role in their population dynamics. Through their effect on size at metamorphosis, factors in the pre- metamorphic environment often have profound effects upon survival and fecundity in the post-metamorphic environment. Here, we adopted a combined experimental and field observational approach to investigate the factors that determine size at metamorphosis in pond-breeding amphibians, and to predict some of their downstream effects on population stability. We set up ecologically realistic mesocosm communities for the endangered California tiger salamander Ambystoma californiense to test the effects of larval density, prey density and hydroperiod on mean size at metamorphosis. We found significant effects for all three factors, with mean size at metamorphosis negatively correlated with larval density and positively correlated with prey density and hydroperiod. We also used six years of field survey data to identify the most informative model explaining mean size at metamorphosis and thus validate our mesocosm results. The optimal three-term model identified terms that were roughly analogous to each of the mesocosm treatments and with similar effect sizes, providing strong field confirmation of our experimental results. The field data also provide correlations between each factor and the number of metamorphs recruited to the population, allowing us to predict the effect of each factor on population stability. Finally, we show that these populations of the endangered A. californiense are strongly resource limited, which has important implications for their management and recovery as an endangered taxon.

Original languageEnglish (US)
Pages (from-to)724-731
Number of pages8
JournalOikos
Volume124
Issue number6
DOIs
StatePublished - Jan 1 2015
Externally publishedYes

Fingerprint

metamorphosis
amphibian
amphibians
mesocosm
hydroperiod
life cycle (organisms)
fecundity
population dynamics
life history
effect
species complex
field survey
breeding
habitats
life cycle
pond
Ambystoma californiense
animals
testing
habitat

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

Cite this

Determinants of size at metamorphosis in an endangered amphibian and their projected effects on population stability. / Searcy, Christopher; Snaas, Helen; Shaffer, H. Bradley.

In: Oikos, Vol. 124, No. 6, 01.01.2015, p. 724-731.

Research output: Contribution to journalArticle

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