Relating quantitative variation within a behavior to variation in transcription

Abstract

Many studies have shown that variation in transcription is associated with changes in behavioral state, or with variation within a state, but little has been done to address if the same genes are involved in both. Here, we investigate the transcriptional basis of variation in parental provisioning using two species of burying beetle, Nicrophorus orbicollis and Nicrophorus vespilloides. We used RNA-seq to compare transcription in parents that provided high amounts of provisioning behavior versus low amounts in males and females of each species. We found no overarching transcriptional patterns distinguishing high from low caring parents, and no informative transcripts that displayed particularly large expression differences in either sex. However, we did find subtler gene expression differences between high and low provisioning parents that are consistent across both sexes and species. Furthermore, we show that transcripts previously implicated in transitioning into parental care in N. vespilloides had high variance in the levels of transcription and were unusually likely to display differential expression between high and low provisioning parents. Thus, quantitative behavioral variation appears to reflect many transcriptional differences of small effect. Furthermore, the same transcripts required for the transition between behavioral states are also related to variation within a behavioral state.

Keywords: Nicrophorus; RNA-seq; burying beetle; gene set enrichment analysis; parental care; quantitative trait transcripts.

Figure 1

Gene set enrichment analysis of transcripts predicted from N. vespilloides females. The top 100 differentially expressed transcripts from N. vespilloides females are (A) significantly DE in N. vespilloides males, (B) not DE in N. orbicollis females, and (C) moderately DE in N. orbicollis males.

Figure 2

Gene set enrichment analysis of transcripts predicted from N. orbicollis females. The top 100 differentially expressed transcripts from N. orbicollis females are (A) moderately DE in N. orbicollis males, (B) significantly DE in N. vespilloides females, and (C) not DE in N. vespilloides males.

Figure 3

The variance of transcripts implicated in caring versus random genes. Transcripts differentially expressed between caring and non-caring N. vespilloides (Parker et al. 2015) show higher expression variance among caring parents than random transcripts in both (A) N. vespilloides females and (B) N. vespilloides males.

Figure 4

Gene set enrichment analysis of transcripts previously implicated in caring. The 752 transcripts found in our data set that were differentially expressed between caring and non-caring N. vespilloides from Parker et al. (2015) are (A) moderately DE in N. vespilloides females, and (B) significantly DE in N. vespilloides males.