Meeting Abstract
Threespine sticklebacks (Gasterosteus aculeatus ) are a classic example of sensory drive, which predicts covariation in sensory environments, visual systems, and signals that result in divergent mate preferences, and drive reproductive isolation. In the breeding season, male sticklebacks develop a bright red throat but in many western North American freshwater rivers and streams, the red throat has been lost and males instead have ‘black’ or ‘melanic’ body coloration. In contrast to the classic system, populations that differ in expression of the red throat in Washington differ dramatically in male competition, but not female preference. We utilize this system to evaluate if visual systems co-vary with signals involved in male competition. At least two molecular mechanisms can explain variation in visual sensitivity. Sequence differences in the opsin protein or differential expression of opsin genes can alter spectral sensitivity. In sticklebacks, there is little variation in spectral sensitivity or opsin sequences. However, several recent studies show that opsin expression can evolve very rapidly and is plastic, changing in response to environmental conditions on very small spatial and temporal scales. We evaluated opsin expression patterns in 1 red population and in 3 black populations that differ in age of colonization from 16,000 to millions of years, and likely represent independent losses of red coloration. Using qPCR methods assessing relative levels of gene expression of opsins, we test 1) if opsin expression differs between populations that differ in male breeding color and 2) if opsin expression varies in parallel across populations representing independent changes in color with different times since colonization. Our results highlight the role of visual systems in mediating male competition in the stickleback system.
