Evolution
of Lake Malawi Cichlids
 Lake
Malawi harbors more species of fish than does any other lake in the world;
in fact, its 1000+ species constitute greater diversity than exists among
all of the lakes of North America and Europe combined. At least 98%
of Malawi species are members of the family Cichlidae, and greater than
95% of these occur nowhere else.
We are currently examining the genetic basis for dorsal fin coloration in the Metriaclima zebra species complex in Lake Malawi. This complex consists of 13 described species as well as a number of forms less formally delimited. Many of these taxa have very restricted distributions within the lake, and these local endemics often differ in male breeding coloration as well. We would like to know whether similar-looking forms from different parts of the lake are monophyletic (that is, derived from a common ancestor which subsequently dispersed to multiple localities) or whether they represent a case of convergent or parallel evolution (with shared color characteristics arising independently from a widely-distributed but generalized ancestral form). However, because these and other cichlid species in Lake Malawi have evolved so recently, no reliable phylogeny exists to serve as a reference for the history of speciation events. For her M.S. thesis project, Paulette Reneau is employing classical Mendelian genetics to indirectly assess the monophyly of color morphs from allopatric localities. By crossing similar color forms from different parts of the lake, she hopes to determine whether the genes controlling color attributes are allelic; if this is the case, 'hybrid' lines should breed true for the shared color characteristics. On the other hand, segregation of alternative phenotypes in F1 or F2 hybrids would indicate that the genetic basis for the color traits resides at different loci in the two parental forms. We are also involved in crossing these color variants with more 'wild-type' forms from the same part of the lake to look at the effective number of genes involved in the control of various color attributes. This work is being done in collaboration with Dr. Irv Kornfield at the University of Maine. We are also collaborating with Dr. Joseph Bilotta in the WKU Department of Psychology to look at responses of retinal bipolar cells in members of the Metriaclima zebra complex. Preliminary ERGs of both on- and off-bipolar cells indicate the presence of multiple cone types that conform well to predictions made from microspectrophotometric analysis of photoreceptors and to analysis of opsin gene DNA sequences (Karen Carleton, pers. comm.). Click
here to learn more about cichlids and their amazing behavior, ecology
and evolution.
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Conservation
of Colorado River Gila
 Species
of the cyprinid genus Gila from the upper Colorado River Basin are
among the most endangered fish species in the world. At the same
time, several species display extremely unusual morphologies that likely
reflect adaptations to the whitewater habitat in which they are found.
The group as a whole also is characterized by a complex evolutionary history
involving natural hybridization coupled with selection to maintain distinct
species-specific phenotypes.
We have been examining patterns of morphological variation among isolated populations of several of these species from throughout the upper Colorado River basin. We are interested both in uncovering the role of hybridization in determining patterns of shape variation within and among localities, as well as how an understanding of such patterns can influence or direct development of conservation and management strategies. We have found that hybridization strongly influences shape differences in two species but that, despite the high level of gene flow between species, it is possible to identify individuals to species with a fairly high degree of certainty. We have also used the situation in Gila as a model for exploring the more general problem of how to deal with endangered taxa which may (naturally or not) be hybridizing with closely-related, non-endangered species. We have framed this problem in terms of the 'Producer's vs. Consumer's Risk Gambit' and suggested that this may provide a useful way of prioritizing recovery efforts for imperiled taxa. Click
here for a list of related publications.
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Analysis
of Molecular Systematic Data
 With
the advent of highly sensitive molecular markers used to survey population
genetic structure, it is essential to develop and understand the behavior
of analytical methods to deal with the high level of variability inherent
in the data. At the same time, it is interesting to consider how
patterns derived from the statistical analysis of systematic data might
be used to infer the evolutionary processes underlying those patterns.
Jennifer Reninga is examining the behavior of Monte Carlo randomization tests for geographic heterogeneity under various sample sizes and allele frequency distributions as part of her undergraduate honors thesis research project. In particular, she is looking at patterns of allelic diversity typical of microsatellite DNA markers and how such distributions might influence Type I error rates. By applying the widely-used Monte Carlo approach to one of the newest and most sensitive classes of molecular markers, we hope to establish a framework for designing data collection and analysis strategies that will be robust in the face of high variability. For his honors thesis project, Micah Wilcox is quantifying the fractal dimension of phylogenetic trees taken from the literature. Because of the balance between generation of new lineages (via mutation or speciation) and the loss of such lineages via extinction, one would expect the length of branches in a phylogenetic tree to increase from the tips of the tree to the root (similarly to the way real trees are self-pruning); however, given that we don't expect branch lengths to be constant, it is difficult to know how long we would expect a particular branch to be under a null model involving uniform rates of speciation and extinction. By determining the extent to which phylogenetic trees are fractal in nature, we hope to be able to provide both branch length predictions based on a null model as well as indicate those points on a given tree where additional evolutionary processes must be invoked to account for the patterns observed in the tree (that is, when branches are longer or shorter than would be expected). Click
here for a list of related publications.
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Wildlife
Molecular Forensics
 Much
of Kentucky's wildlife was decimated during the 19th century through overharvesting,
indiscriminate logging, burning and overgrazing of habitat by domestic
livestock. By the mid-1800s, bison, elk, black bear, mountain lion,
timber wolf and red wolf had been largely extirpated; whitetail deer populations
had similarly crashed by the early 1900s. Since that time, combinations
of harvest restrictions, effective law enforcement and active restoration
efforts have restored a robust whitetail deer herd, and have begun to lead
to restoration of other species to the Commonwealth.
Kinchel Doerner, Bonnie J. Furman and I are currently involved in a project employing microsatellite-DNA markers in the population genetic analysis of whitetail deer. We are examing spatial patterns of genetic variation across Kentucky using seven highly-polymorphic marker loci; at the same time, we are developing molecular protocols for use in prosecuting suspected cases of poaching and other illegal harvesting of deer. To date, the four undergraduate students involved in the project (Wes Braden, Tom Cunninham, Jennifer Reininga and Amanda Rice) have developed several multiplex-PCR protocols and genotyped nearly 500 deer from 5 regions throughout the state; they are currently employing various population genetic analysis to examine levels of variability and population structure within the Kentucky herd. This work is funded by a Research Enhancement Grant from Kentucky NSF EPSCoR, and is being conducted in collaboration with the Kentucky Department of Fish and Wildlife Resources and the University of Maine Molecular Forensics Laboratory. We are extending this approach
to other species of wildlife returning to Kentucky, including elk and black
bear. The Elk Restoration Project being conducted by KDFWR is the
most ambitious attempt yet to reintroduce elk to areas in which they were
historically abundant. The goal of this project is to develop a self-sustaining
and huntable herd by 2007. Using microsatellite markers developed
through the whitetail deer project, we will be monitoring the genetic consequences
of this reintroduction (including the fate of individual alleles, temporal
and spatial changes in allele frequency) in real-time. In addition,
Dr. Bonnie J. Furman is involved in a project examining the genetic diversity
and distribution of black bear in the Commonwealth, as a prelude to development
of managemnt strategies aimed at restoring a viable population of bear
to Kentucky.
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Publications
CICHLIDS
McElroy, D.M., I. Kornfield and J. Everett. 1991. Coloration in African cichlids: diversity and constraints in Lake Malawi endemics. Neth. J. Zool. 41: 250-268. McElroy, D.M. and I. Kornfield. 1990. Sexual selection, reproductive behavior, and speciation in in the mbuna species flock of Lake Malawi (Pisces: Cichlidae). Envir. Biol. Fishes 28: 273-284. GILA
McElroy, D.M., J.A. Shoemaker and M.E. Douglas. 1997. Discriminating Gila robusta and Gila cypha: risk assessment and the Endangered Species Act. Ecol. Appl. 7: 958-967. McElroy, D.M. and M.E. Douglas. 1995. Patterns of morphological variation among endangered populations of Gila robusta and Gila cypha (Teleostei: Cyprinidae) in the upper Colorado River basin. Copeia 1995: 636-649. MOLECULAR
DATA ANALYSIS
McElroy, D., P. Moran, E.
Bermingham and I. Kornfield. 1992. REAP: an integrated environment
for the manipulation and phylogenetic analysis of restriction data.
J. Hered. 83: 157-158.
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