Research Interests

Research Interests

I consider myself to be an ecological and evolutionary biologist in the broadest sense of the word. My interests have spanned many aspects of organismal biology, including the phylogeny, evolution, cytogenetics, reproduction, and ecology in mammals, especially bats. I have been ventured far from mammals by participating with others in studies of algae, fish, and vascular plants at population, community, and ecosystem levels.  My current interests include both laboratory and field-based studies.   The laboratory studies involve computer graphic and statistical methods to describe and analyze biological form to answer evolutionary questions. This emerging field -- geometric morphometrics -- allows one to describe shape variation and seeks answers to questions concerning how and why biological forms differ. Specific projects I am pursuing now include  1) ecomorphological study of body form and life history traits in darters and Gulf Coast populations of the black-tailed shiner, Cyprinella venusta (with Drs. David Heins and Michael Guill),  2) geographic variation and the impact of environmental stress in Louisiana muskrats (Ondatra zibethicus) and 3) shape analysis and sexual dimorphism in a variety of mammals (bats and primates).

Field studies  include --  1) patterns of vegetation structure and environmental gradients in Yucatan dry tropical forests (with Dr. David White),  2) patterns of phenotypic plasticity in Mississippi River delta populations of roseau cane, Phragmites australis (with Drs. David White and Don Hauber),   3) the distribution, ecology, and conservation status of mammals of Louisiana,   4) study of mammalian biodiversity in Jean Lafitte National Park (see below).


 Mammal Survey of Jean Lafitte National Historical Park

With the support of a NPS Inventory and Monitoring Program grant, we have initiated field studies to document the mammals inhabiting the Barataria and Chalmette units of the Jean Lafitte National Historical Park and Preserve.  Visit our website below to learn more and follow our progress.

JLNP Mammal Website


Patterns of plant species diversity and functional ecology

I have collaborated with Loyola colleagues, Drs. David A. White (plant community ecologist) and Don Hauber (plant population geneticist) to study patterns of plant species diversity and interaction at various spatial and temporal scales.   Dr. David White has conducted field studies in the dry forests of the Yucatan Peninsula for nearly 20 years, publishing the first comprehensive description of woody tree flora in 1995 (White & Darwin, 1995).  We followed that work with a multivariate analysis of 10-m quadrats along a 50 km transect, published in the Journal of Vegetation Science (White & Hood, 2004).

Field studies on plant communities of the Belize delta of the Mississippi River Delta have been conducted by Loyola researchers for over 20 years.   Dr. David White has maintained a longterm study site since 1983 (see White, 1993).  Since the early 1990s, David White and Don Hauber have studied the population ecology and genetics of the common reed (Phragmites australis) and have published two important papers describing the distribution of genotypes in the delta (Hauber et al., 1991; Fournier et al., 1995; Pellegrin & Hauber, 1999).   I joined their research group and we have recently published a morphological analysis of Phragmites of the delta (White et al., 2004).   We are developing new field and greenhouse studies to investigate the ecology and evolutionary biology of Phragmites in this unique wetland landscape.


Ecomorphological study of body size/shape in Cyprinella venusta and darters

Dr. David C. Heins (Tulane University), myself and our students are pursuing an integrated ecomorphological approach to studying body shape (and size) change in freshwater fishes of the Mississipi Gulf Coastal region.  Our studies of body shape (and size) variation in the blacktail shiner, Cyprinella venusta, are focused on understanding the factors effecting the evolution and maintenance of sexual dimorphism in this species.  Abiotic factors include physical features of stream/river systems (e.g., drainage size, total runoff, flow rate), whereas biotic factors include life history features, feeding styles, and mating behavior.  We are using geometric morphometric methods to describe and analyze body shape variability and its relationship to size, age, and reproductive traits.

Hood & Heins (2000) represents our initial description of sexual dimorphism in shape during ontogeny.  Current research is focused on seasonal and geographic variation and on its relationship to biotic and abiotic variables.  We are initiating swimming performance studies to investigate the relationship of patterns of shape variability and swimming hydrodynamics.

Dr. J. Michael Guill, David Heins and I have conducted studies of geometric morphometrics in darters.   To date, we have published 2 papers (Guill, Hood & Heins, 2003 and Guill, Heins & Hood 2003).    These studies focus on evaluating how body shape is effected by phylogeny (paper in Systematic Biology) and within closely related species (paper in Ecology of Freshwater Fish).  Current studies will present the interplay of body shape and life history traits and the coevolution of body shape, life history, and phylogeny.


Sexual Size (and Shape) Dimorphism

My interests in the study of secondary sexual dimorphism flow from my general interests in geographic variation in natural populations.   Sexual Size Dimorphism (SSD) has been described in many organisms, ever since Darwin (1859) and is apparently commonly observed in many mammals, including bats.  Our ongoing studies on the overall body form in Cyprinella venusta involves dimorphism in both size and shape (Hood & Heins, 2000).   Other studies in our lab on Louisiana populations of the muskrat, Ondatra zibethicus, also demonstrate a very strong signal of both size and shape dimorphism (Hood, 2000).

Although SSD has been noted in many organisms, few studies have been able to clearly identify causal factors.  Our studies on sexual dimorphism in freshwater fish and mammals share a common thread of a population-level of study and a focus on shape variability.

Selected SSD Literature


Fluctuating Asymmetry

Although bilateral symmetry is a major feature of many organisms, variations from symmetry are well known.  Van Valen (1963) described three forms of asymmetry, including a subtle form known as fluctuating asymmetry.  During the past 40 years, numerous workers have investigated FA and its relationship to various population genetic and evolutionary processes (see esp. reviews by Palmer & Strobeck, 1986; Markow, 1993; Palmer, 1996; Moller & Swaddle, 1998).  Our lab has been investigating FA and its relationship to environmental stress in Louisiana populations of the muskrat for several years.  Our study material includes a large museum collection of muskrat skulls collected from the field in 1939-40.  These skulls exhibit FA to varying degrees at different specific localities. 



Tulane Museum of Natural History

Department of Ecology & Evolutionary Biology

I have had a deep commitment to supporting and using Natural History museums as teaching and research tools for the study of evolution, biodiversity, and natural resource management since 1977.  My graduate studies included a curatorial assistant position in the Section of Mammals, Los Angeles County Museum of Natural History, and close working relationships with major collections (AMNH, Carnegie Museum, Field Museum, LSU Mus. Nat. Sci., The Museum at Texas Tech, and USNM).  I have served as Adjunct Curator of Mammals in the Tulane Museum of Natural History since 1990, and currently work in the collections on a regular basis.

Tulane Museum Natural History
Tulane Dept. of EEB
Museum Web Links

I also participate in graduate education as an adjunct faculty member in Tulane's Department of Ecology & Evolutionary Biology.  I have served on graduate committees to a number of M.S. and Ph.D. students, and currently serve as committee member and research advisor to two EEB Ph.D. graduate students -- Lauren Nolfo and Jennifer Coulson.  Please feel free to visit the EEB website (link above), or contact me if you have any interests in graduate studies.


Southeastern Louisiana Ecology & Evolutionary Biology Group

Formed in 1989, the SE Louisiana EEB Group has as its goals the support of research and education in Ecology and Evolutionary Biology through the interaction among faculty and research scientists from area institutions. The seed for the development of an interest group of ecologists and evolutionary biologists in Southeastern Louisiana came from the belief that a broad interaction among educators and researchers in this region would benefit us all.   Members are Ph.D. faculty and educators from most of our region's academic institutions.  Each year, we gather for a special annual lecture, hosted by one of the local institutions, featuring an eminent scientist. These lectures seek to help invigorate faculty and students and draw attention to SE Louisiana as a place where ecology and evolutionary biology "happens".

EEB Group Website



Send comments to  chood@loyno.edu
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Illustrations by Jean Cassels (jean-cassels.com)