Meeting Abstract
Recent research into whether independently evolved phenotypes share underlying mechanisms has provided examples of both extreme convergence and divergence in mechanisms. One implication of shared mechanisms contributing to parallel evolutionary transitions is the possibility that developmental or genetic constraints limit adaptation, whereas divergent mechanisms suggest that mechanistic flexibility facilitates evolution. We measured the extent to which shared transcriptional signatures evolve independently in Trinidadian guppies (Poecilia reticulata) adapting to common environments. We found evidence that a combination of consistent and unique transcriptional mechanisms contribute to similar adaptive phenotypes across parallel evolutionary events. In addition, we developed novel statistical methods to analyze whether patterns of connectivity among genes also evolve. We demonstrated that covariance structure among differentially expressed transcripts differ across populations, and that the distribution of connectivities among differentially expressed transcripts differs from that of non-differentially expressed transcripts. Despite inherent issues of non-independence of expression among genes within a network, transcriptional studies exploring changes in coexpression among genes are almost entirely lacking. Our results indicate that changes in patterns of connectivity among genes may play an important role in phenotypic evolution, and we suggest that transcriptional flexibility may facilitate rapid evolution during adaptation to novel environments.
