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Theories of ecological diversification make predictions about the timing and ordering of character state changes through history. These theories are testable by "reconstructing" ancestor states using phylogenetic trees and measurements of contemporary species. Here we use maximum likelihood to estimate and evaluate the accuracy of ancestor reconstructions.(More)
Molecular clocks are widely used to date phylogenetic events, yet evidence supporting the rate constancy of molecular clocks through time and across taxonomic lineages is weak. Here, we present 90 candidate avian clock calibrations obtained from fossils and biogeographical events. Cross-validation techniques were used to identify and discard 16 inconsistent(More)
Are measurements of quantitative genetic variation useful for predicting long-term adaptive evolution? To answer this question, I focus on gmax , the multivariate direction of greatest additive genetic variance within populations. Original data on threespine sticklebacks, together with published genetic measurements from other vertebrates, show that(More)
We present evidence of ecological character displacement among species of threespined sticklebacks that inhabit small lakes of coastal British Columbia. Geological data suggest that the populations resulted from multiple divergence and speciation events over the past 13,000 yr. In lakes with two species, one is invariably "limnetic" in morphology and(More)
The fitness function f relates fitness of individuals to the quantitative trait under natural selection. The function is useful in predicting fitness differences among individuals and in revealing whether an optimum is present within the range of phenotypes in the population. It may also be thought of as describing the ecological environment in terms of the(More)
Major phenotypic changes evolve in parallel in nature by molecular mechanisms that are largely unknown. Here, we use positional cloning methods to identify the major chromosome locus controlling armor plate patterning in wild threespine sticklebacks. Mapping, sequencing, and transgenic studies show that the Ectodysplasin (EDA) signaling pathway plays a key(More)
The genetic and molecular basis of morphological evolution is poorly understood, particularly in vertebrates. Genetic studies of the differences between naturally occurring vertebrate species have been limited by the expense and difficulty of raising large numbers of animals and the absence of molecular linkage maps for all but a handful of laboratory and(More)
BACKGROUND Many different environmental and genetic sex-determination mechanisms are found in nature. Closely related species can use different master sex-determination switches, suggesting that these developmental pathways can evolve very rapidly. Previous cytological studies suggest that recently diverged species of stickleback fish have different sex(More)
ECOLOGICAL SPECIATION (see Glossary) occurs when DIVERGENT SELECTION on traits between populations or subpopulations in contrasting environments leads directly or indirectly to the evolution of REPRODUCTIVE ISOLATION. The concept of ecological speciation dates back to the 1940s, from the time the BIOLOGICAL SPECIES CONCEPT was developed. Dobzhansky 1(More)