Alleles underlying larval foraging behaviour influence adult dispersal in nature

Abstract

The dispersal and migration of organisms have resulted in the colonisation of nearly every possible habitat and ultimately the extraordinary diversity of life. Animal dispersal tendencies are commonly heterogeneous (e.g. long vs. short) and non-random suggesting that phenotypic and genotypic variability between individuals can contribute to population-level heterogeneity in dispersal. Using laboratory and field experiments, we demonstrate that natural allelic variation in a gene underlying a foraging polymorphism in larval fruit flies (for), also influences their dispersal tendencies as adults. Rover flies (for(R) ; higher foraging activity) have consistently greater dispersal tendencies and are more likely to disperse longer distances than sitter flies (for(s) ; lower foraging activity). Increasing for expression in the brain and nervous system increases dispersal in sitter flies. Our study supports the notion that variation in dispersal can be driven by intrinsic variation in food-dependent search behaviours and confirms that single gene pleiotropic effects can contribute to population-level heterogeneity in dispersal.

Habitat connectivity is determined by the scale of habitat loss and dispersal strategy

“…Finally, due to the size of our experimental arenas, our study limited movements to walking. However, the simple tube‐to‐tube assay accurately mirrors rover/sitter dispersal patterns in nature (Edelsparre et al., 2014). Furthermore, the goal of our study was not to estimate realized dispersal thresholds in nature nor the end‐points of dispersal; rather, we set out to demonstrate the importance of considering the interaction between interpatch distance and dispersal strategy when assessing the degree of connectivity in landscapes.…”

“…In both laboratory and field trials, homozygous for s individuals exhibit a dispersal‐limited phenotype relative to homozygous for R individuals (more dispersive) (Edelsparre et al., 2014). Individuals homozygous for for s (sitters) are characterized by lower for ‐mRNA expression levels and protein activity (PKG) relative to individuals with the for R allele (rovers) (Osborne et al., 1997).…”

“…Strains were kept on a yeast–sugar–agar medium (40 ml) in 170 ml plastic bottles (VWR) with sponge tops on a 12/12‐hour light/dark cycle at 23 ± 2°C (standard conditions; see Edelsparre et al., 2014). Experimental flies were collected upon emergence from pupae and kept in 90 ml plastic vials under standard conditions until they were between 5 and 7 days old.…”

“…The proportion of dispersers was quantified as the proportion of flies that had moved to the other chamber. Previous chamber‐to‐chamber dispersal assays on this system yielded rover/sitter differences in dispersal at distances of 4 cm over 6 hr (Edelsparre et al., 2014). This simple laboratory assay is an accurate predictor of rover/sitter dispersal in nature (Edelsparre et al., 2014).…”

“…Previous chamber‐to‐chamber dispersal assays on this system yielded rover/sitter differences in dispersal at distances of 4 cm over 6 hr (Edelsparre et al., 2014). This simple laboratory assay is an accurate predictor of rover/sitter dispersal in nature (Edelsparre et al., 2014). To simulate decreasing connectivity between the two patches, we exposed new flies to similar dispersal assays as described above, but we connected the two chambers with tubing lengths of 20 cm, 40 cm, and 80 cm, in separate trials.…”