Showing papers by "Jonathan B. Losos published in 1995"
TL;DR: It is demonstrated theoretically and via simulations that relaxation of the hidden assumptions that speciation is essentially instantaneous and occurs independently in separate lineages leads to qualitatively different expectations concerning the expected phylogenetic topology.
Abstract: Evolutionary biologists increasingly have become interested in the factors determining the structure of phylogenetic trees. For example, highly asymmetric trees seem to suggest that the probability of extinction and/or speciation differs among lineages. Before looking for the cause of such differences, one must establish that the structure of the trees differs significantly from results of an appropriate null model. A commonly invoked null model assumes that speciation is equally probable along all branches of a diversifying tree and predicts that highly asymmetric trees are not unexpected. However, this model of diversification assumes more than equality of rates among lineages. We demonstrate theoretically and via simulations that relaxation of the hidden assumptions that speciation is essentially instantaneous and occurs independently in separate lineages leads to qualitatively different expectations concerning the expected phylogenetic topology. In particular, highly asymmetric trees are considerably ...
71 citations
TL;DR: Phylogenetic analyses indicate that not only are Anolis communities on Jamaica and Puerto Rico convergent in structure, but they have attained their similarity by evolving through a nearly identical sequence of ancestral communities.
Abstract: Phylogenies can be useful not only as a means of examining evolutionary hypotheses, but also as a source of hypotheses that can be tested using extant taxa. I illustrate this approach with examples from the study of community evolution in Caribbean Anolis lizards. Phylogenetic analyses indicate that not only are Anolis communities on Jamaica and Puerto Rico convergent in structure, but they have attained their similarity by evolving through a nearly identical sequence of ancestral communities. Examination of the pattern of community evolution suggests that interspecific competition is the driving force behind anole adaptive radiation. This hypothesis can be tested by investigating whether anoles shift their habitat use in the presence of competitors and, if so, whether such shifts lead to morphological adaptation to the new habitat. These hypotheses have been tested experimentally by introducing lizards onto small islands. Preliminary results indicate the existence of ecological interactions among sympatric anoles and that shifts in habitat use are accompanied by microevolutionary changes in morphology.
63 citations