A field study by Beren Robinson on the threespine stickleback fish in the lake of coastal British Columbia showed some evidence of divergent natural selection. First, the study will be described. Next, the findings for the study and how the findings support evolution and natural selection. Finally, a proposed second study will be given.
Study Description Beren Robinson reason for the field study was to determine if the constraints of two distinct environments affect the evolution of the stickleback species. He sampled a population where only a single species that tended to be the intermediate in morphology and habit to the limnetic or open-water and benthic or near shore water species. He then hypothesized that the individuals represented distinct phenotypes that were products of natural selection promoting divergence within the population. Robinson thought that trade-offs occurred when one task resulted in the cost of performance and fitness of other task. For example the limnetic species feeding on the plankton in open waters at the cost of being able to feed on sediments in shallow water while the benthic species feed on sediments in shallow waters at the cost of feeding on plankton in open waters. So Robinson’s decide to first variable to test was if the morphological differences between the two species were heritable or an expression of phenotypic plasticity due to the different habitats or diets. Second, to see if trade-offs were occurring by testing the two species by influencing their foraging efficiency.
Testing Results Beren Robinson decided to test his first variable by rearing offspring of the two species under identical environmental conditions and diet. The results of this test showed that there was some degree of
