Landscape genetics of a specialized grasshopper inhabiting highly fragmented habitats: a role for spatial scale

• Published in: Diversity & distributions Vol. 18; no. 5; pp. 481 - 492
• Main Authors: Ortego, Joaquín, Aguirre, Maria P., Cordero, Pedro J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.05.2012; Blackwell Publishing; Blackwell; John Wiley & Sons, Inc
• Subjects: Animal, plant and microbial ecology; Applied ecology; BIODIVERSITY RESEARCH; Biological and medical sciences; Causal modelling; Conservation; Ecological genetics; Evolutionary genetics; Fundamental and applied biological sciences. Psychology; Gene flow; General aspects; Genetic diversity; genetic structure; Genetic variation; Genetics of eukaryotes. Biological and molecular evolution; Habitats; historical barriers; Insects; Landscape ecology; landscape genetics; Landscapes; Macroecology; population fragmentation; Population genetics; Population genetics, reproduction patterns; Population structure; River basins; Landscape; genetic structure; Barrier; Genetic diversity; Spatial scale; Biodiversity; Population genetics; Case history; Modeling; Fragmentation; Causal modelling; population fragmentation; landscape genetics; Habitat; historical barriers
• ISSN: 1366-9516; 1472-4642
• DOI: 10.1111/j.1472-4642.2011.00840.x

Aim: The study of geographical discontinuities in the distribution of genetic variability in natural populations is a central topic in both evolutionary and conservation research. In this study, we aimed to analyse (1) the factors associated with genetic diversity at the landscape spatial scale in the highly specialized grasshopper Mioscirtus wagneri and (2) to identify the relative contribution of alternative factors to the observed patterns of genetic structure in this species. Location: La Mancha region, Central Spain. Methods: We sampled 28 populations of the grasshopper M. wagneri and genotyped 648 individuals at seven microsatellite loci. We employed a causal modelling approach to identify the most influential variables associated with genetic differentiation within a multiple hypothesis-testing framework. Results: We found that genetic diversity differs among populations located in different river basins and decreases with population isolation. Causal modelling analyses showed variability in the relative influence of the studied landscape features across different spatial scales. When a highly isolated population is considered, the analyses suggested that geographical distance is the only factor explaining the genetic differentiation between populations. When that population is excluded, the causal modelling analysis revealed that elevation and river basins are also relevant factors contributing to explaining genetic differentiation between the studied populations. Main conclusions: These results indicate that the spatial scale considered and the inclusion of outlier populations may have important consequences on the inferred contribution of alternative landscape factors on the patterns of genetic differentiation even when all populations are expected to similarly respond to landscape structure. Thus, a multiscale perspective should also be incorporated into the landscape genetics framework to avoid biased conclusions derived from the spatial scale analysed and/or the geographical distribution of the studied populations.