Positive selection and comparative molecular evolution of reproductive proteins from New Zealand tree weta (Orthoptera, Hemideina)

Abstract

Animal reproductive proteins, especially those in the seminal fluid, have been shown to have higher levels of divergence than non-reproductive proteins and are often evolving adaptively. Seminal fluid proteins have been implicated in the formation of reproductive barriers between diverging lineages, and hence represent interesting candidates underlying speciation. RNA-seq was used to generate the first male reproductive transcriptome for the New Zealand tree weta species Hemideina thoracica and H. crassidens. We identified 865 putative reproductive associated proteins across both species, encompassing a diverse range of functional classes. Candidate gene sequencing of nine genes across three Hemideina, and two Deinacrida species suggests that H. thoracica has the highest levels of intraspecific genetic diversity. Non-monophyly was observed in the majority of sequenced genes indicating that either gene flow may be occurring between the species, or that reciprocal monophyly at these loci has yet to be attained. Evidence for positive selection was found for one lectin-related reproductive protein, with an overall omega of 7.65 and one site in particular being under strong positive selection. This candidate gene represents the first step in the identification of proteins underlying the evolutionary basis of weta reproduction and speciation.

New Zealand Tree and Giant Wētā (Orthoptera) Transcriptomics Reveal Divergent Selection Patterns in Metabolic Loci

“…2000). This pattern was also observed among H. thoracica and H. crassidens male reproductive associated proteins (Twort et al. 2017).…”

Chromosome-level genome assembly provides insights into adaptive evolution of chromosome and important traits in the geckoGekko japonicus

“…PKD2L2 plays a important role in reproduction and is an essential gene for spermatogenesis (Chen et al 2008;Dolebo et al 2019), which suggests that the reproductive system of G. japonicus have undergone adaptive evolution. PKDREJ and PKD2L2, two reproduction-related genes, have higher ω values relative to other TRP genes, which is consistent with previous studies finding that reproduction-related proteins have higher evolutionary rates (Swanson et al 2001;Swanson and Vacquier 2002;Clark et al 2006;Walters and Harrison 2010;Walters and Harrison 2011;Wilburn and Swanson 2016;Twort et al 2017). TRPM3, TRPM5 and TRPM8 are thermo-sensitive TRP genes (Wang and Siemens 2015), which suggests that their genomic changes may be related to the evolution of thermoregulation in G.…”

“…positive selection, and that they diverge rapidly between taxa(Swanson et al 2001;Swanson and Vacquier 2002;Clark et al 2006;Walters and Harrison 2010;Walters and Harrison 2011;Wilburn and Swanson 2016;Twort et al 2017). …”

Explaining large mitochondrial sequence differences within a population sample

“…One coding, putatively neutral nuclear locus (Sperm flagallar protein; Sflag; [ 62 ]) was amplified and sequenced, and coded as genotype data for analysis in combination with microsatellite loci. The 400 bp fragment of the nuclear gene (Sflag) was amplified and sequenced using the primers TWnucSflagF (5′-TCGCCAGTTCAGACCTAGGATGAGG-3′) and TWnucSflagR (5′-TGGCTCTGTACAAGGCTGGGA-3′) [ 62 ]. Only two Sflag alleles were detected and as some wētā were homozygous at this locus, heterozygote individuals could be identified and genotyped as they contained two nucleotides at each of the three sites that differentiate the two alleles.…”

“…One coding, putatively neutral nuclear locus (Sperm flagallar protein; Sflag; [62]) was amplified and sequenced, and coded as genotype data for analysis in combination with microsatellite loci. The 400 bp fragment of the nuclear gene (Sflag) was amplified and sequenced using the primers TWnucSflagF (5 -TCGCCAGTTCAGACCTAGGATGAGG-3 ) and TWnucSflagR (5 -TGGCTCTGTACAAGGCTGGGA-3 ) [62].…”