Tracking dispersal across a patchy landscape reveals a dynamic interaction between genotype and habitat structure

Abstract

Theoretical and empirical studies often show that within populations, individuals vary in their propensity to disperse. We aspired to understand how this behavioural variation is impacted by the distribution and pattern of food patches across a landscape. In a series of experiments we examined how inter-patch distance and the distribution of food patches influenced dispersal in wild-type strains of Drosophila melanogaster with natural allelic variants of the foraging (for) gene known to influence dispersal in this species. The 'rover' strain was homozygous for the for R allele (more dispersive) whereas the 'sitter' strain was homozygous for for s (less dispersive). We also assessed an outbred population of flies with an unknown dispersal propensity. Dispersal was assayed in a multi-patch lab arena (25 cells, 5 × 5 array). In the inter-patch distance trials, landscapes of two different sizes (small versus large) were used, both with food in all 25 cells. Dispersal was reduced in the large landscape relative to the small landscape for all three fly strains. Sitter dispersal was lowest relative to both rovers and the outbred flies, whose dispersal tendencies were similar. In the patch distribution trials, flies were assayed in landscapes with varying distribution and number of cells containing food. Dispersal generally increased as the number of patches with food increased, however, rovers and sitters adopted similar dispersal strategies when food was fixed and limited. Conversely, their strategies differed when the total amount of food increased with the number of patches. We find that both the inter-patch distance and distribution can influence dispersal. However, the effect of inter-patch distance and distribution on dispersals depends on genotype × environment interaction. Our findings highlight the importance of considering G × E when assessing how dispersal strategies and landscape dynamics influence the distribution of animal communities.

Tribolium castaneum: A Model Insect for Fundamental and Applied Research

“…Gene expression manipulation effects on how beetles exploit landscapes and analysis of gene expression patterns under different landscape environments appear to be promising areas of research to understand how beetles exploit landscapes and how this process might be manipulated in pest management. Wild-type strains of D. melanogaster with natural allelic variants of the rover and sitter forager gene adopted different movement patterns under certain landscape patterns when evaluated on experimental landscapes with varying distribution and number of cells containing food (42). This highlights how genotype expression can be influenced by environmental factors such as landscape pattern.…”

Transcriptomic effects of the foraging gene shed light on pathways of pleiotropy and plasticity

“…Larval pathlength is plastic, with both sitters and rovers responding to food deprivation by decreasing their pathlengths 11 . Sitters and rovers also differ in their adult foraging and locomotory behavior, with rovers showing higher food‐search behavior, food intake, and dispersal compared to sitters in the lab and in the wild 14,15 . As with larval pathlength, adult foraging behavior is plastic in response to food deprivation 16 .…”

“…11 Sitters and rovers also differ in their adult foraging and locomotory behavior, with rovers showing higher food-search behavior, food intake, and dispersal compared to sitters in the lab and in the wild. 14,15 As with larval pathlength, adult foraging behavior is plastic in response to food deprivation. 16 Furthermore, sitters and rovers differ in a variety of other food-related traits (e.g., fat storage, 3,17,18 starvation resistance, 3,19 and metabolism 20 ) and in nonfood-related traits (e.g., nociception, 21 social behavior, 22 and learning and memory 23,24 ).…”

Effects of environment and genotype on dispersal differ across departure, transfer and settlement in a butterfly metapopulation

“…This can lead to complex outcomes at each of the three stages of dispersal, especially if intrinsic differences interact with extrinsic factors (e.g. genotype-by-environment interactions; [30][31][32][33]). However, these interactions are rarely considered in field studies (but see [34][35][36]) and to our knowledge have not been tracked through distinct dispersal stages.…”