Do common dispersal influences inform a large lizard’s landscape-scale gene flow?

• Published in: Evolutionary ecology Vol. 36; no. 6; pp. 987 - 1006
• Main Authors: Jessop, Tim S., Smissen, Peter, Anson, Jennifer R., Sherman, Craig, Sumner, Joanna M.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.12.2022; Springer; Springer Nature B.V
• Subjects: Animal Ecology; Animals; Bias; Biomedical and Life Sciences; Dispersal; Dispersion; Ecology; Evolutionary Biology; Females; Forests; Gene flow; Genes; Genetic structure; Geographical distribution; Habitats; Influence; Lace; Landscape; Life Sciences; Lizards; Males; Monitors; Original Research; Plant Sciences; Population density; Population genetics; Populations; Prey; Sex; Sex ratio; Spatial analysis; Woodlands; Adaptive dispersal; Gene flow; Reptile; Ecotone; Geographic structuring; Landscape resource gradients
• ISSN: 0269-7653; 1573-8477
• DOI: 10.1007/s10682-022-10208-2

The dispersal tendencies of individuals can provide an important adaptive basis to counter environmental and ecological variation to increase fitness and benefit populations. We evaluated whether indirect genetic-based measures of dispersal of a large monitor lizard ( Varanus varius ) were sex-biased and further covaried with putative demographic and ecological differences across a forest ecotone in Southern Australia. The mean corrected assignment index (i.e., mAI C ) estimated that lace monitors had significant male-biased dispersal. There was strong evidence that common dispersal promoting influences, including lace monitor density and arboreal mammal prey availability, but not the overall male-biased sex ratio, differed with forest type across the ecotone. These different forest types influenced the extent of sex-biased dispersal, with lace monitors captured in banksia woodland having a significant male bias in dispersal, whilst lace monitors sampled in adjacent eucalypt forest showed no difference in assignment values indicating no sex-biased dispersal. However, individual-based spatial autocorrelation analyses and mixed effect models indicated no spatial mediated genetic structuring nor evidence of sex or habitat-related effects. Estimates of recent migration (i.e., < 3 generations) indicated strong and symmetrical migration between banksia woodland and eucalypt forest patches suggesting limited habitat resistance to gene flow across an ecotonal landscape. Not discounting method-specific evidence for male- and forest-type-biased dispersal, the absence of spatial genetic structuring suggests lace monitors retain a high dispersal capacity. An absence of landscape-scale genetic structure is consistent with this species’s high vagility. This landscape-scale result is further supported because only the most significant biogeographic barriers (e.g., mountain ranges) impede gene flow within the species’ extensive range distribution, allowing for genetic structuring among populations.