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Genetic variation in pathogen‐induced early hatching of toad embryos
Author(s) -
GOMEZMESTRE I.,
TOUCHON J. C.,
SACCOCCIO V. L.,
WARKENTIN K. M.
Publication year - 2008
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2008.01509.x
Subject(s) - hatching , biology , hatchling , embryo , zoology , maternal effect , phenotypic plasticity , genetic variation , genetics , evolutionary biology , ecology , gene , pregnancy , offspring
Accelerated hatching is one of few defences available to embryos, and is effective against many egg‐stage risks. We present the first analysis of genetic variation in hatching plasticity, examining premature hatching of American toad embryos in response to pathogenic water moulds. We reared eggs from half‐ and full‐sib families in the presence and absence of water mould. Hatching age and hatchling size showed low cross‐environment genetic correlations, suggesting that early‐induced hatching can evolve largely independently of spontaneous hatching. We found less phenotypic and additive genetic variation for early‐induced hatching than spontaneous hatching, and a stronger correlation between egg and induced hatchling sizes. Directional selection by the pathogen may have eroded variation in early‐induced hatching, pushing it against the constraint of hatching gland development. Later hatching has a second, muscular component. This pattern of variation may characterize defences based on developmental transitions, although other inducible defences show more variation in induced phenotypes.