Abstract Detail

Comparative Genomics/Transcriptomics

Roberts, Wade [1], Roalson, Eric [2].

Gene co-expression network connectivity is an important determinant of selective constraint during flower diversification in the magic flowers (Achimenes).

Gene networks provide a systematic understanding of molecular mechanisms underlying biological processes. To date, very few studies have attempted to examine how network connectivity and selection interact to shape natural variation in gene expression and influence the evolution of adaptive phenotypes. Most studies have explored these patterns within populations of a single species. Here, we explore how variation in gene expression and network connectivity influences floral diversification among multiple species in the same genus. We tested the hypothesis that conserved sets of genes are involved in the convergent evolution of floral forms in the magic flowers (Achimenes). Using RNA-seq to assay gene expression across two stages of flower development in 12 closely related gesneriad species, we inferred co-expression networks that clustered genes into 28 modules. Most modules were strongly correlated with floral phenotypic differentiation associated with bee-, butterfly-, and hummingbird-pollination. Within the co-expression networks, differentially expressed genes were underrepresented in module cores and overrepresented in network peripheries. We found that highly connected genes have experienced stronger selective constraint on coding sequence, with both gene connectivity and centrality associated with signatures of selection. Additionally, transcription factors were neither more nor less connected than other genes and were under stronger selective constraint than other genes. Our integrated results suggest that conserved, functionally important genetic modules underlie the development and diversification of floral form and that connectivity within the co-expression network is linked to the strength of purifying selection.

1 - Washington State University, School Of Biological Sciences, P.O Box 644236, Pullman, WA, 99164, United States
2 - Washington State University, School Of Biological Sciences, Abelson Hall 339, Pullman, WA, 99164, United States

Keywords:
Achimenes
co-expression network
flower diversification
Gesneriaceae
pollination syndrome
selective constraint
transcriptomics.

Presentation Type: Oral Paper
Session: 21, Comparative Genomics and Transcriptomics I
Location: 102/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 10:15 AM
Number: 21009
Abstract ID:600
Candidate for Awards:None