Beren Robertson Field Study

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Beren Robinson Field Study
Bio 315

Beren Robinson Field Study
The three-spine sticklebacks are one group of fish that inhabits lakes in the northern regions of North America, where lakes were formed after ice sheets that covered the region retreated. This group of fish has gone through a rapid period of speciation, with the species that inhabits the lakes of coastal British Columbia being the youngest species (Smith & Smith, 2009). Beren Robinson of the University of Guelph Department of Zoology primary focus was to find out if constraints posed by the difficult environments were partly the cause of the evolution of the three-spine sticklebacks. Robinson’s field study in in Cranby Lake in the coastal areas of British Columbia was an important study in the field of evolution, and will be further discussed here in. In the lakes where a pair of three-spine stickleback species is found, one species is found in open waters and feeds on the plankton in the open water zone, limnetic form, while the second species is found in shallower waters eating larger prey from the sediments and vegetation, benthic form. In the lakes where only one species occurs, the species are usually found to be intermediate in morphology and habitant to the limnetic and benthic (Smith & Smith, 2009). In Cranby Lake, Robinson was studying an intermediate species, the Gasterosteus aculeatus, when it was observed that individuals sampled from the open water habitat were morphologically different than those from the shallower waters (Smith & Smith, 2009). From this observation, Robinson hypothesized that “these individuals represented distinct phenotypes that are products of natural selection promoting divergence within the population” (Smith & Smith, 2009). To test his hypothesis, Robinson had to first discover if the morphological differences between the two was heritable and if the differences influenced the foraging efficiency. Robinson tested the first condition by...
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