LE3 .A278 2016

2016

Gibson, Glenys

Acadia University

Bachelor of Science

Honours

Biology

Biology

Species with developmental plasticity produce more than one morph of offspring in different environments. How important is the parental environment in determining offspring morph (i.e., is form transmitted epigenetically across generations) or can embryos “correct” the phenotype induced by mum’s environment? I tested the relative importance of parental and embryonic environment on developmental plasticity in the marine invertebrate Polydora cornuta, a species that produces two morphs of larvae (dispersive and non-dispersive). My first hypothesis is that larval phenotype is determined by parental environment; therefore, offspring phenotype should not be altered by subsequent treatment of embryos prior to the maternal-zygotic genome transition. My second hypothesis is that embryonic environment will over-ride effects of maternal environment. Parents were cultured in four groups: seawater (control), folate/B12, Bisphenol A, and methionine. For hypothesis 1, broods were isolated from control parents before the maternal-zygotic transition and exposed to the treatments described above (n=7broods, 302 larvae). Exposure of early embryos to BPA and methionine induced a shift towards the production of more small larvae (i.e., dispersive larvae; one-way ANOVA, df=3, 299, p≤0.0001) indicating that embryonic environment does influence larval form. For hypothesis 2, both parents and embryos were exposed to the treatments in a nested design (embryos nested within parental treatment). Both parental and embryonic environment affected larval phenotype, with embryonic environment overriding maternal environment in some cases (GLM, df=1, 15, p≤0.0001). These results indicate that both maternal and embryonic environments influence plasticity in offspring phenotype.

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https://scholar.acadiau.ca/islandora/object/theses:1459