Testing hypotheses about evolutionary change on single branches of a phylogeny using evolutionary contrasts

Article Abstract:

A research extends the method of evolutionary contrasts to allow character change along a set of single branches on a phylogeny to be studied. It presents expected variances showing that these extensions also results in a set of contrasts uncorrelated due to common ancestry. This method helps in testing specific hypotheses about the phenotypic variation caused by the evolutionary forces and the degree of rates of change in single characters along particular types of branches by isolating the change along single branches.

Models, Phylogeny

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The evolution of dispersal in spatially and temporally varying environments

Article Abstract:

Phenotypic and genetic variation in dispersal characters within and among communities and environmental sensitivity of dispersal propensity was quantified in experiments. A two-patch model was studied to analyze how patterns of spatial and temporal variation in carrying capacities affect natural selection on dispersal. A certain amount of dispersal was preferred by selection under most conditions of habitat variability. The system also defined parameters for coexistence of competing species in different environments.

Growth, Species, Species (Biology), Competition (Biology), Animal ecology

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Chaotic population dynamics favors the evolution of dispersal

Article Abstract:

Dispersal or the movement between population is favored by chaotic population dynamics in constant but patchy environments. In such systems, subpopulations on different patches with minimally different initial conditions will diverge as their population curves unfold. In the long term, the rank order of geometric growth rate or fitness among patches should vary, even if the environment is constant. A model which illustrates the basic effect of this pattern is presented.

Analysis, Environmental aspects, Biology, Chaos theory, Chaotic systems

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