| Summary: | Sockeye salmon exhibit great ecological diversity among populations. During the last glacial period, ice covered much of what today are freshwater habitats. As the glaciers retreated, sockeye colonized new freshwater habitats from relatively few glacial refugia. Colonizing populations adapted at a very fine spatial scale among river drainages, tributaries and lakes within rivers, and even divergent habitats within lakes. All of this occurred within the past 15,000 years since the last glacial maximum. This resulted in many thousands of locally adapted populations and a grand display of the process of evolution within a species. In this dissertation, I explore genetic and phenotypic diversity in the dynamic and changing environments of Aniakchak National Monument and Preserve as well as Katmai National Park in southwest Alaska. Recent eruptions at Aniakchak include events 500 and 79 years ago and the caldera presently contains sockeye salmon populations spawning in different habitats. Using genetic tools, I find that ecological divergence occurred in egg size and body depth in less than 500 years or 100 generations. Secondly, sockeye salmon exhibit a broad life history division by rearing habitat; some populations rearing in lakes (lake-type sockeye) and others rearing in rivers (riverine sockeye). I describe differences in juvenile body shape and relate these to differences in foraging strategy and predation. Finally, I apply gene expression technology to understand the life history differences and the molecular trade-offs in sockeye salmon populations. I start with a review of recent technological advances that relate gene expression to ecology, evolution, and the formation and maintenance of new species. I then relate functional, expressed genes in muscle tissue to lake-type and riverine juvenile populations. This provides an ecological context to genes that are normally only described in artificial situations. Taken together, this work furthers the understanding of the interaction of ecology and evolution, from genes to populations to broad life history types.
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