Evolutionary Genetics of Fishes

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My research program focuses on understanding the genetic basis of evolutionary change in fishes. In particular I am concentrating on two major components of the evolutionary process. Firstly, I study how genetic differences among individuals lead to variation in their appearance (phenotype) and numbers and survival of their offspring (fitness). Secondly, I determine how those genetic differences can become partitioned between populations when they begin to diverge genetically into different species. I examine different forms (morphs) of Arctic charr from Iceland that differ in size, appearance, feeding habits and ecology, and live together in different lakes. In particular I am determining the way in which these different forms might have arisen, and also investigating the role of such forms in the origin of new species. Arctic charr continue to be models for this work because of their remarkable phenotypic and genetic diversity and the ability to produce experimental families. Knowledge of the genes that control the appearance of Arctic charr and how their appearance is shaped through the evolutionary agent of natural selection is needed to evaluate the role of such morph variation in population divergence. First, we will determine if we see the same patterns of morph appearance and their genotypes across lakes. Next, we will determine if natural selection favors fish with certain body shapes and sizes. This will involve sampling fish from two Icelandic lakes over three years and seeing if fish with typical morph appearance are larger at a given age and females have bigger ovaries and more eggs when they mature. Third, we will search for chromosomal regions that influence body morphology as well as the size and shape of individual bones of the head and see if the genes in these regions have been influenced by natural selection. The knowledge generated by this research is essential to tacking the question of whether these morphs of Arctic charr are evolutionarily stable or whether we are witnessing the birth of new species.