Low effective population sizes and limited connectivity in xerothermic beetles: implications for the conservation of an endangered habitat

Abstract

AbstractFragmentation and isolation may have detrimental effects on the viability of populations. Xerothermic grasslands, which are extra‐zonal analogues of steppes, are among Europe's most endangered natural environments. Information about connectivity between the remaining habitat patches is critical for effective conservation planning. However, very little is known about the actual levels of isolation of individual xerothermic patches at the inter‐regional and local scale. In this study, 16 microsatellite loci were used to investigate genetic diversity, structuring, effective sizes (Ne), and connectivity among populations of the weevil Centricnemus leucogrammus at various geographic scales. Analysis of 22 populations from three geographic regions, differing in the time of origin and the degree of geographic isolation of the populations, showed that the isolated populations from northern Poland showed the least variability, whereas those from central Poland and Ukraine sustained a similar level of microsatellite variability and were moderately connected within regions. Very low effective sizes (Ne = 14–44) were estimated, and signatures of bottlenecks were detected in all populations. Effective sizes were generally higher in larger xerothermic patches, which constitute a good quality habitat, and in populations sampled in nature reserves, as opposed to unprotected turfs. Such information is useful for the design of conservation and management plans. As C. leucogrammus is characteristic of xerothermic and steppic habitats in central and eastern Europe, it may be considered an excellent target species for assessing the quality of xerothermic habitats as well as estimating and monitoring their connectivity.