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Research Focus
The Langerhans Lab is broadly interested in the evolution of biological diversity and the predictability of evolution. Our work seeks a better understanding of the forces generating phenotypic differentiation and speciation. To this end, we employ comparative analyses of multiple populations and multiple species across multiple environments, in combination with experiments examining the links between phenotype, performance, and fitness. We have a strong emphasis on investigating the mechanisms responsible for morphological and locomotor diversification in fishes.
A large component of our work focuses on the role of predators (piscivorous fish) and other selective agents in the evolutionary diversification of small livebearing fishes in the genus Gambusia (native to USA, Central America, and Caribbean). A fundamental component of this work is an assessment of the accuracy with which we might predict the course of evolution from first principles, building evolutionary predictions from biomechanics (form-function relationships) and ecology (performance-fitness relationships).
Major Research Topics:
Evolutionary Significance of Predation
Ecological Speciation
Ecology and Evolution of Swimming Performance
Genital Evolution
Some Other Ongoing Research Areas:
Can species traits predict invasiveness or susceptibility to extinction?:
We are examining many species in the genus Gambusia that vary in their invasiveness and susceptibility to extinction in order to evaluate whether these aspects may be predicted using species' evolutionary histories and multivariate trait combinations.
Indirect community effects and the ecology of phenotypic plasticity:
This work seeks to clarify the terminology used to define the different types of indirect community effects and evaluate the importance of phenotypic plasticity in generating community patterns. Other than antipredator behaviors in animals, the ecological consequences of phenotypic plasticity has largely been unexplored. Current work seeks to understand the role of developmental plasticity in community structure and dynamics.
Evolutionary significance of water flow for fish morphology and locomotion:
We investigate intra- and interspecific morpohlogical divergence in several groups of fishes between flow regimes (e.g., low vs. high velocity of water current). So far, we have documented morphological shifts associated with water velocity in South American cichlids and characins (Langerhans et al. 2003, ongoing work with Craig Layman, FIU), an East African cyprinid (Langerhans et al. 2007), and Gambusia fishes (Langerhans and Reznick in press). A recent meta-analysis further tested the predictability of phenotpyic differentiation across flow regimes in fishes (Langerhans 2008).
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