Conservation of Adaptive Diversity in a Tropical Lizard: Identifying Anthropogenic Threats to Evolutionary Processes with Remote Sensing Data.EPA Grant Number: F6F20461
Title: Conservation of Adaptive Diversity in a Tropical Lizard: Identifying Anthropogenic Threats to Evolutionary Processes with Remote Sensing Data.
Investigators: Freedman, Adam H
Institution: University of California - Los Angeles
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2006 through September 1, 2009
Project Amount: $105,938
RFA: STAR Graduate Fellowships (2006) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Biology/Life Sciences , Fellowship - Ecology , Fellowship - Evolutionary Biology
Ongoing anthropogenic habitat fragmentation and future climate change will likely alter genetic and phenotypic variation within wild animal and plant populations. These alterations may prevent species from adaptively responding to future environmental change, leading to their extinction. Nevertheless, it is not always clear which processes are most important for maximizing adaptive variation, and thus which to target in conservation plans. This is particularly true in the case of tropical rainforests. Two of the prevailing hypotheses regarding mechanisms for maintaining variation in tropical taxa are the Forest Refugia (FRH) and Divergence-with-Gene-Flow (DWGF) hypotheses. FRH stipulates that isolation of populations in tropical forest refugia during the Pleistocene is the primary means by which variation is generated, while the DWGF stipulates that natural selection along environmental gradients is the primary driver, occurring in the face of substantial gene flow between populations adaptively responding to local conditions. The research project uses a rainforest lizard, Euprepis affinis, recently revised from the Genus Mabuya) to test these competing hypotheses, and usessatellite imagery to assess how ongoing human activities are altering evolutionary processes that generate and maintain variation within E. affinis.
To (1) test DWGF in the rainbow skink (Mabuya affinis), in Cameroon and Ghana, (2) test FRH in M. affinis in Cameroon, Ghana, and Ivory Coast, and (3) using satellite imagery, examine whether ongoing anthropogenic impacts are altering evolutionary processes that generate intraspecific genetic and morphological variation.
Skinks in populations aligned along the ecological gradient between rainforest and savanna-gallery forest mosaic will be captured. Measurements will be taken of morphological traits that have been previously been shown to be subject to natural selection in lizards. Tissue samples will be collected for genetic analyses. Patterns of genetic differentiation between populations will be examined using 10 polymorphic microsatellite markers, and sequence data from the mitochondrial gene ND4. Multivariate and phylogenetic reconstruction methods will be used to tests the predictions of DWGF and FRH concerning relationships between morphological, genetic, and environmental variation. Several satellite-derived data layers representing climate, fire frequency, vegetation, and habitat fragmentation will be used to assess human impacts on natural vegetation. Temporal trends will be used to assess vegetation change within hypothesized rainforest refugia and along the rainforest-savanna gradient. Multivariate analyses will be used to identify which environmental variables influence morphological and genetic variation in E. affinis, and changes in those variables over time will be used to make inference regarding alteration of evolutionary processes due to human activity.
Preliminary data indicate that there is both morphological and genetic differentiation along the rainforest-savanna gradient. Thus, it is expected that divergence-with-gene flow will be important along the gradient. At present, an additional role for refugia cannot be ruled out. It is also expected that significant shifts in the vegetation structure of the ecological gradient and the forest cover within hypothesized refugia will be detected, and that regimes of natural selection and gene flow between populations will likely be changed in the future.