Data from: The developmental transcriptomes of two sea biscuit species with differing larval types

Background: Larval developmental patterns are extremely varied both
between and within phyla, however the genetic mechanisms leading to this
diversification are poorly understood. We assembled and compared the
developmental transcriptomes for two sea biscuit species (Echinodermata:
Echinoidea) with differing patterns of larval development, to provide a
resource for investigating the evolution of alternate life cycles. One
species (Clypeaster subdepressus) develops via an obligately feeding larva
which metamorphoses 3-4 weeks after fertilization; the other (Clypeaster
rosaceus) develops via a facultatively feeding larva that can develop
through metamorphosis entirely based on egg provisioning in under one
week. Results: Overall, the two transcriptomes are highly similar,
containing largely orthologous contigs with similar functional annotation.
However, we found distinct differences in gene expression patterns between
larvae of the two species. Larvae from C. rosaceus, the facultative
planktotroph, turned genes on at earlier stages and had less
differentiation in gene expression between larval stages, whereas, C.
subdepressus showed a higher degree of stage-specific gene expression.
Conclusion: This study is the first genetic analysis of a species with
facultatively feeding larvae. Our results are consistent with known
developmental differences between the larval types and raise the question
of whether earlier onset of developmental genes is a key step in the
evolution of a reduced larval period. By publishing a transcriptome for
this rare, intermediate, larval type, this study adds developmental
breadth to the current genetic resources, which will provide a valuable
tool for future research on echinoderm development as well as studies on
the evolution of development in general.