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The molecular mechanisms underlying major phenotypic changes that have evolved repeatedly in nature are generally unknown. Pelvic loss in different natural populations of threespine stickleback fish has occurred through regulatory mutations deleting a tissue-specific enhancer of the Pituitary homeobox transcription factor 1 (Pitx1) gene. The high prevalence(More)
Most adaptation is thought to occur through the fixation of numerous alleles at many different loci. Consequently, the independent evolution of similar phenotypes is predicted to occur through different genetic mechanisms. The genetic basis of adaptation is still largely unknown, however, and it is unclear whether adaptation to new environments utilizes(More)
How do developmental mechanisms evolve to control changing skeletal morphology, the shapes and sizes of individual bones? We address this question with studies of the opercle (OP), a large facial bone that has undergone marked morphological evolution in the ray-finned fish. Attributes for developmental analysis motivated us to examine how OP shape and size(More)
The history of life offers plentiful examples of convergent evolution, the independent derivation of similar phenotypes in distinct lineages. The emergence of convergent phenotypes among closely related lineages (frequently termed "parallel" evolution) is often assumed to result from changes in similar genes or developmental pathways, but the genetic(More)
The diversity and abundance of non-long terminal repeat (LTR) retrotransposons (nLTR-RT) differ drastically among vertebrate genomes. At one extreme, the genome of placental mammals is littered with hundreds of thousands of copies resulting from the activity of a single clade of nLTR-RT, the L1 clade. In contrast, fish genomes contain a much more diverse(More)
The importance of trophic ecology in adaptation and evolution is well known, yet direct evidence that feeding controls microevolution over extended evolutionary time scales, available only from the fossil record, is conspicuously lacking. Through quantitative analysis of tooth microwear, we show that rapid evolutionary change in Miocene stickleback was(More)
Natural selection has almost certainly shaped many evolutionary trajectories documented in fossil lineages, but it has proven difficult to demonstrate this claim by analyzing sequences of evolutionary changes. In a recently published and particularly promising test case, an evolutionary time series of populations displaying armor reduction in a fossil(More)
This paper describes an integration of hypertext browsing and authoring facilities into a syntax-directed programming environment. The editor's recognition of the programming language building blocks has been exploited not only to guide program entry, but to break programs into units which can be connected into a hyperdocument. Comments and documentation(More)
—Inferring the causes for change in the fossil record has been a persistent problem in evolutionary biology. Three independent lines of evidence indicate that a lineage of the fossil stickleback fish Gasterosteus doryssus experienced directional natural selection for reduction of armor. Nonetheless, application to this lineage of three methods to infer(More)
We tested the hypothesis that increased telencephalon size has evolved in threespine stickleback fish (Gasterosteus aculeatus) from structurally complex habitats using field-caught samples from one sea-run (ancestral) and 18 ecologically diverse freshwater (descendant) populations. Freshwater habitats ranged from shallow, structurally complex lakes with(More)