Many anurans exhibit complex interactions with conspecifics during early life-history stages, including plastic responses to chemical cues during development. In the cane toad (Rhinella marina) a waterborne chemical cue released by tadpoles suppresses the growth and survival of developing embryos. This species-specific suppressor pheromone might provide an avenue for targeted control across the toad’s invasive range in Australia. Yet, we know little about how gene expression changes underlie conspecific suppression.
Using RNA-Seq we quantified gene expression from tadpoles exposed to three older conspecifics during embryonic development (suppressed) and compared the profiles to tadpoles that developed without exposure (control), for four full-sibling clutches – two from both the invasion front and the long colonised range-core.
We find significant suppression of growth, but not developmental stage, at the invasion front but not the range-core. However, clutches from both regions exhibit differential expression between treatments. Thirteen genes down-regulated in suppressed tadpoles (from both regions) are mainly involved in regulating innate immune responses. In contrast, uniquely down-regulated genes at the invasion front also regulate immune responses, while those uniquely up-regulated have roles in energy production, maintenance of epithelia and other physiological processes – including development.
Our results provide new insights into the physiological processes involved in suppression of conspecifics, suggesting a trade-off between maintaining immune responses and development. The candidate genes identified here could be vital to future efforts of invader control in this species.
Funding Sources: CIE, Deakin University (MR); ARC DE150101393 (LA); FL120100074 (RS).