Sean T. Giery’s presentation on “The Evolutionary Ecology of Communication in Bahamian mosquitofish” led to a plethora of information on a little known fish in our waters. According to Giery, the Bahamian mosquitofish (Gambusia spp.) is only about an inch in length.
As a focal point of his presentation, he spoke specifically about the presence or absence of colour on the mosquitofish’s dorsal fin, and the evolution and dynamics of this trait.
For Giery’s research, a number of fish from Abaco that range in various shapes and colours were selected. He discovered that fish collected from the unblocked side of the sea were more colourful, while those on the unblocked side were dull.
He wanted to determine if the colour of surrounding habitat or the presence of predatory fish had anything to do with the colour of the fish. In determining how visual signals form, Giery made a comparison between fish and peacocks. It was evident that bright colours made the peacocks subject to greater predation. Female preference was also a factor in promoting elaborate colours, and it is thought that they prefer such an extreme trait as an indication of health.
Giery captured 10-30 male mosquitofish from six populations, their color was measured in Photoshop, and their weight was recorded. The mosquitofish with red dorsal fins appeared to be heavier.
The presence of predators was considered along with water colour. Predator surveys of 22 populations were conducted with 15 to 60 fish per site; however, there was a strong signal that water colour was affecting the colour of the fish. Other factors that impact the mosquitofish, too, though are overexploitation, invasive species, pollution and habitat alteration.