From connectivity to isolation: genetic consequences of population fragmentation in capercaillie across Europe

Abstract

The capercaillie inhabits a continuous range in large parts of the Palearctic boreal forest, but is patchily distributed in temperate Europe. An ongoing population decline, largely related to human land use changes, has been most pronounced in central and western Europe, where some local populations have become extinct. In this study, we document the genetic differentiation of capercaillie populations at different stages along a gradient of spatial structuring from high connectivity (continuous range in the boreal forest) to a metapopulation systems (Alps) and recent (central Europe) and historic (Pyrenees) isolation. Four hundred and sixty individuals from 14 sample sites were genotyped at 10 polymorphic microsatellite loci to assess genetic structure and variation of capercaillie populations across its European range. As expected, differentiation was least pronounced within the continuous range in the boreal forest. Within the metapopulation system of the Alps, differentiation was less than among the isolated populations of central Europe (Black Forest, Fichtelgebirge, Thuringia, Vosges). In the long-isolated population of the Pyrenees, and the recently isolated populations of central Europe, genetic diversity was significantly reduced compared with the Alps and boreal forest. Our results agree with the concept of a gradual increase in genetic differentiation from connectivity to isolation, and from recent to historic isolation. Anthropogenic habitat deterioration and fragmentation thus not only leads to range contractions and extinctions, but may also have significant genetic and evolutionary consequences for surviving populations. To maintain high levels of genetic variation in species in fragmented habitats, conservation should aim at securing connectivity between spatially distinct populations.

Genetic Variability of Polish Population of the CapercaillieTetrao urogallus

“…Samples R-U and R-K presented level of genetic variability, expressed in terms of allelic diversity and heterozygosity, generally higher than in each of Polish populations and comparable with results obtained for Russian Capercaillies in other studies (Segelbacher et al 2003). However, it seems likely that most Polish populations retained quite large portion of variability in microsatellite loci.…”

“…In the case of LSF, Car and AF differences with Russian populations in allelic diversity were not significant. Moreover, mean numbers of alleles per locus in these Polish populations (magnitudes from 4.7 to 5.0) were higher than the estimate reported by Segelbacher et al (2003) for the Capercaillie population from Slovenia (A = 3.7), where the number of individuals is estimated at more than 30 000, and very similar to the estimate for Black Forest (Germany) (A = 5.1), where the total population size is estimated at 1000 individuals. However, our study applied different sets of microsatellite markers, thus comparisons can be questionable.…”

“…A high level of genetic diversity was also found to be maintained in local, spatially isolated Alpine populations through existence of gene flow (Segelbacher & Storch 2002). In small, isolated populations from Central Europe an increased level of genetic structure was found, and the authors suggested that this structuring and decrease in genetic variability are connected with the low effective population size, restricted gene flow and disturbance in functioning of a former metapopulation system (Segelbacher et al 2003). Until now, genetic investigations of Polish populations of the Capercaillie have not been carried out.…”

“…Genetic variability assessed by the analysis of microsatellite polymorphism and genetic structure of Central and West-European populations of the Capercaillie has been carefully studied (Segelbacher & Storch 2002, Segelbacher et al 2003). The studies presented greater level 28 R. Rutkowski et al…”

Forest as Capercaillie’s habitat: applied research efforts and new management experiences

“…La progressiva perdita e frammentazione degli habitat favorevoli hanno determinato anche in ambito alpino una situazione di piccole popolazioni con differenti gradi di interconnessione, fino al completo isolamento (Storch 2000, Mollet et al 2003. Si tenga anche conto di come le popolazioni poco numerose siano generalmente vulnerabili e mostrino un alto rischio di estinzione a causa della stocasticità ambientale e di eventi demografici, o per perdita di variabilità genetica (Segelbacher et al 2003).…”