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Grant Haines

McGill Biology/Redpath Museum
Student Speaker | Étudiant.e
Because they are subject to new suites of selective pressures, phenotypes of introduced populations are expected to evolve rapidly in response to their new environments. This is especially true in cases where the ancestral populations are well-adapted to their environments, and conditions in the new environment differ from those of the ancestral population. However, it is difficult to discern patterns in the rates of evolutionary change following introductions, the role of sexual dimorphism in rapid evolutionary change, and whether change in integration structures of anatomical modules or changes in the morphology of the modules themselves drive adaptive change without repeated sampled populations. Here I use geometric morphometric analyses of micro-CT scans of repeatedly sampled specimens from an introduced population of threespine stickleback (Gasterosteus aculeatus) on Graham Island in Haida Gwaii to discern patterns of adaptation following an introduction. The introduced population was stocked into a shallow roadside pond in 1993, has a prey community consisting primarily of benthic macroinvertebrates, and is becoming increasingly to adapted to benthic feeding. The ancestral population from Mayer Lake, which is large and has a stickleback prey community dominated by zooplankton, is adapted to limnetic feeding and has unusually large and long-lived individuals. I tested whether rates of phenotypic change increased following the introduction, whether the introduction increased morphological disparity or changed the degree of sexual dimorphism, and whether in resulted in a breakdown in the morphological integration in trophic modules.