Abstract
Yellow anacondas (Eunectes notaeus) are large, semiaquatic boid snakes found in wetland systems in South America. These snakes are commercially harvested under a sustainable management plan in Argentina, so information regarding population structuring can be helpful for determination of management units. We evaluated genetic structure and migration using partial sequences from the mitochondrial control region and mitochondrial genes cyt-b and ND4 for 183 samples collected within northern Argentina. A group of landscape features and environmental variables including several treatments of temperature and precipitation were explored as potential drivers of observed genetic patterns. We found significant population structure between most putative population comparisons and bidirectional but asymmetric migration in several cases. The configuration of rivers and wetlands was found to be significantly associated with yellow anaconda population structure (IBD), and important for gene flow, although genetic distances were not significantly correlated with the environmental variables used here. More in-depth analyses of environmental data may be needed to fully understand the importance of environmental conditions on population structure and migration. These analyses indicate that our putative populations are demographically distinct and should be treated as such in Argentina's management plan for the harvesting of yellow anacondas.
Highlights
Genetic data offer high resolution and power for evaluating population structure and dispersal patterns, which is especially useful in species that are difficult to find or observe such as yellow anacondas
We evaluated the plausibility of patterns of isolation by environmental distance (IBED), where some environmental variables would better explain the genetic distance patterns [4]
Our analysis revealed clear evidence of spatial structure of yellow anacondas in the study area
Summary
Genetic data offer high resolution and power for evaluating population structure and dispersal patterns, which is especially useful in species that are difficult to find or observe such as yellow anacondas. Yellow anacondas in northern Argentina are good candidates for these types of landscape genetics studies as they are found in a heterogeneous environment, with presumably limited opportunities for dispersal between populations [1]. May be important in limiting dispersal, a phenomenon known as isolation by environmental distance (IBED) [4] Landscape features such as presence and directionality of rivers (both present and historic) can contribute to our understanding of relationships between populations [5,6,7,8]. By jointly evaluating the spatial patterns of genetic structure and magnitude and directionality of gene flow between yellow anaconda populations in this heterogeneous area, we can better understand factors influencing dispersal in these and possibly other large semiaquatic snakes
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