Lunglessness in plethodontid salamanders is consistent with the hypothesis of a mountain stream origin: a response to Ruben and Boucot

Article Abstract:

The hypothesis that lunglessness in the salamander family Plethodontidae indicates its Appalachian highland origin is defended. Geological evidence disproves the claim that Late Mesozoic Appalachia lacked upland environments with fast-flowing, cool streams that select for lunglessness. Furthermore, the life history patterns of the members of the family show that lunglessness is a rheotropic adaptation to primarily allow larval forms to survive in streams. A review of the life history, morphology, physiology and ecology of larval salamanders is presented to support the original hypothesis.

Genetic aspects, Salamanders, Adaptation (Biology), Evolutionary adaptation, Plethodontidae, Plethodontid salamanders

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Intercontinental correlation of geographical ranges suggests stasis in ecological traits of relict genera of temperate perennial herbs

Article Abstract:

The correlation between the geographical ranges of vicariantly disjunct genera of herbaceous perrenial plants relict to temperate forests of eastern Asia and eastern North America was calculated to understand long-term stasis in ecological traits. A significant correlation in area of geographical range of the plant populations was found, although the plants have been separated for ten or even thirty million years. It is suggested that evolutionary stasis is a result of ecological specialization to subsets of ecological conditions that persist inspite of changing ecological conditions.

Perennials, Perennial plants, Vegetation dynamics

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Competition and the effect of spatial resource heterogeneity on evolutionary diversification

Article Abstract:

A model is presented to depict how the form of natural selection resulting from resource competition is impacted by spatial resource heterogeniety. Findings show that spatial resource heterogeniety can reduce the likelihood that certain forms of evolution will occur, such as character displacement, and has a disruptive effect if habitat patch migration is low.

Canada, Statistical Data Included, Models, Habitat (Ecology), Habitats, Competition (Biology), Morphology (Animals), Animal morphology, Resource partitioning (Ecology)

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