Early ontogeny shows the same interspecific variation as natural history parameters in the crested newt (Triturus cristatus superspecies) (Caudata, Salamandridae)

Abstract

When the phenotypic divergence within a monophyletic group is characterised by parallel variation of different phenotypic traits, it is very likely that the environment through constraints and/or selection has affected the developmental pathways simultaneously. Such patterns of phenotypic divergence characterise the phenotypic evolution of the crested newts (Triturus cristatus superspecies). In this study, we have examined interspecific variations in the embryonic development of four crested newt species. The species are similar with respect to some basic developmental traits, some morphologically defined developmental stages and the survival rate during early embryogenesis. However, there is significant variation in the developmental rate, as well as differences in the pattern of correlation amongst analysed life-history and developmental traits. Consistent with previous studies, T. dobrogicus appears to be an outlier species, with the longest embryonic period and a significantly different correlation pattern for early life-history and developmental traits. We suggest that the invasion of a novel aquatic environment by T. dobrogicus resulted in large-scale directional changes in development, which could explain parallel change in numerous phenotypic and life-history traits with a high rate of evolution.