Timothy M. Collins
Assistant Professor of Biology
Department of Biological Sciences,
Florida International University, Miami, FL 33199
(305)348-4031 (phone); 305-348-1986 (fax); collinst@fiu.edu (email)
Research Interests
My research interests involve the application of molecular data to address
systematic and evolutionary questions, particularly within the
Mollusca. The molluscus, by virtue of their taxonomic, morphological,
and ecological diversity, as well as an excellent fossil record, are an
especially appropriate group in which to compare results from molecular,
morphological, ecological, and paleontological studies. Congruence of
results from these various sources indicates that we are likely to have
accurately reconstructed the evolutionary history of a group. Discordance
indicates areas for further investigation, and difficulties with one or
more of the data sets in question. My current research program is
focused on two different levels: 1) gene order as a tool for
higher-level systematics among the molluscs and related phyla, and 2)
rates and patterns of sequence evolution in the mitochondrial genome,
and their effect, at various taxonomic levels, on the utility of classes
of molecular characters and phylogenetic methods. The conservation of
gene content and rarity of gene order rearrangements within the animal
mitochondrial genome suggests its utility in resolving questions of
relationships among ancient lineages. These gene order characters are
not subject to the shortcomings that have been attributed to
morphological data (functional convergence) and molecular sequence data
(unequal rate effects) that bear on the question of higher level among
phyla, and underscore the utility of mitochondrial genome rearrangements
as a powerful class of molecular phylogenetic tools to complement
morphological and primary sequence comparisons. Another area of interest
is rates and patterns of sequence evolution, and variation in rates
within and among groups. My research involving sequence comparisons of
species pairs isolated by the Pliocene emergence of the Isthmus of
Panama, as well as species that participated in the Pliocene
Trans-Arctic Interchange between the Northern Pacific and Northern
Atlantic. I have also examined rates of molecular evolution from fossil
occurrences. Finally, I have been investigating the significance of
changing frequencies of the 4 bases A, G, C, and T in DNA sequences
(base compositional effects) in phylogenetic studies. Results to date
indicate that currently used methods of weighting, character-state
reconstruction, rate determination, and significance testing (of
phylogenetic hypotheses) are sensitive to the degree of base
compositional bias, and that in the case of animal mitochondrial
genomes, these patterns of base compositional bias are at least
partially driven by the necessity for large portions of animal
mitochondrial protein encoding genes to be hydrophobic. Research in the
near future will focus on collecting molecular, morphological, and
paleontological data to arrive at a robust phylogeny of the gastropods as
a test case of methods of determining degrees of confidence, congruence,
and resolving conflict in phylogenetic studies.
Selected Papers
Boore, J. L.,Collins, T. M., Stanton, D., Daehler, L. L., and W.
M. Brown. 1995 Deducing the pattern of arthropod phylogeny from
mitochondrial DNA rearrangements. Nature v. 376 163-165.
Collins, T. M. 1996. in press Molecular comparisons of
transisthmian species pairs: Rates and patterns of evolution. in:
Environmental and Biological Change in Neogene and Quaternary Tropical
America. Jackson, J.B.C., Coates, A.G., and A. Budd eds.
Collins, T. M., Kraus, F., and G. Estabrook. 1994. Compositional
effects and weighting of nucleotide sequences for phylogenetic analysis.
Systematic Biology. v. 43, n. 3, p. 449-459.
Collins, T. M., Wimberger, P., and G. J. P. Naylor.1994.
Compositional bias, character-state bias, and character-state
reconstruction using parsimony. Systematic Biology v. 43, n.4, p.
482-496.
Naylor, G. J. P.,Collins, T. M.,and W. M. Brown. 1995.
Hydrophobicity and Phylogeny. Nature v.373, p. 565-566.