Male Gamhusia holhrooki (Eastern Mosquitofish) express a heritable pigmentation polymorphism approximate to 99% of males are silver, and only approximate to 1% have a melanic, black-spotted pattern. Sex-linkage, an autosomal modifier, and temperature control the expression of this heritable melanism. In many teleosts, melanin also accumulates around the site of parasitic invasion. We have identified black-spot disease in wild mosquitofish from their native habitat. Here, we demonstrate convergence upon the black-pigmented phenotype through two means: 1) heritable melanism, and 2) melanic spotting on the silver genotype that results from infection with immature encysted trematodes. Females are silver and express greater avoidance of metallic males during mating attempts. The resemblance of the black-spotted pattern of the melanic genotype to that of silver genotype infected with trematodes may affect the fitness of melanic males if females perceive them as diseased. Alternatively, females may shun parasitized silver fish because they resemble the metallic genotype, which is larger and has a larger mating organ.
Original Publication Citation
Horth, L., Gauthier, D., & Vogelbein, W. (2013). Heritable melanism and parasitic infection both result in black-spotted mosquitofish. Southeastern Naturalist, 12(1), 209-216. doi:10.1656/058.012.0116
Horth, Lisa; Gauthier, David; and Vogelbein, Wolfgang, "Heritable Melanism and Parasitic Infection Both Result in Black-Spotted Mosquitofish" (2013). Biological Sciences Faculty Publications. 175.
0000-0001-7060-0480 (Horth), 0000-0002-7075-8453 (Gauthier)