Climatic effects on population declines of a rare wetland species and the role of spatial and temporal isolation as barriers to hybridization

Climate change and climatic extremes may affect species directly or indirectly. While direct climatic effects have been intensively studied, indirect effects, such as increasing hybridization risk, are poorly understood.
The goal of our study was to analyse the impact of climate on population dynamics of a rare habitat specialist, Chorthippus montanus, as well as the fine-scale spatial overlap with a sympatric habitat generalist, Chorthippus parallelus and the dispersion of hybrids. We were particularly interested in the role of spatiotemporal overlap on heterospecific encounter frequencies.
We conducted high-precision mark-recapture studies on two sites over 7 years and genotyped 702 individuals of two C. montanus generations to detect hybrids. We tested the performance of three programs (structure, newhybrids and adegenet) and accepted only hybrids detected by the two best performing programs. We then tested for correlations between yearly population trends and climatic variables. F...