Living organisms are under selection not only for one, but also for several
inheritable characters at the same time. Well-sampled and well-supported
phylogenies are necessary for the studies of character evolution and their history.
The poison frogs (Dendrobatidae) are a well-known example of aposematism in
anurans. They include ~270 species of Neotropical frogs with aposematic (toxic
and conspicuous) and non-defended (palatable and cryptic) species. The origin of
aposematism in poison frogs is puzzling, because of its predicted low probability
of establishment due to the prey's increased conspicuousness. Previous studies
suggested a single origin of toxicity and warning coloration. By expanding taxon
sampling of the group, I reexamined the phylogenetic correlation between the
origins of toxicity and warning coloration. I found four or five independent
origins of aposematism; by using simulations, I rejected hypotheses of one, two, or three origins of aposematism (P < 0.002). I also found that diet specialization is
linked with the evolution of aposematism and has evolved independently at least
two times. Poison frogs are endemic to the Neotropic, which is one of the Earth's
largest reservoir of biodiversity. I reconstructed the biogeography of the poison
frog clade and rejected an Amazonian center-of-origin in favor of a model
expanding over the Neotropics. I inferred 14 dispersals into and 18 out of
Amazonia to adjacent regions; the Andes were the major source of dispersals into
Amazonia. Significant percentage of dendrobatid diversity in Amazonia and
Chocó resulted from repeated immigrations, with radiations at <10.0 million years
ago. In contrast, the Andes, Venezuelan Highlands, and Guiana Shield have
undergone extended in situ diversification at near constant rate since the
Oligocene. Poison frogs have significant variation on their physiological
characteristics. I measured resting and active metabolic rates of 54 species. I
traced metabolic measurements along aposematism, diet specialization, molecular
rates, and body mass. I found a synergistic and co-adapted functionality of active
metabolic rates with all previous traits that is perhaps the consequence of the
increase in complexity in most biological systems. My thesis has expanded the
knowledge of the biology, phylogenetic history, and biogeography of the poison
frogs. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/6602 |
| Date | 22 October 2009 |
| Creators | Santos, Juan Carlos |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Format | electronic |
| Rights | Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. |
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