Distribution of genetic variance and isolation by distance in two leaf beetle species: Oreina cacaliae and Oreina speciosissima

Abstract

The distribution of genetic variance was investigated in two closely related Oreina leaf beetle species, Oreina cacaliae and Oreina speciosissima. Populations of these alpine beetles were sampled in mountainous areas of Western Europe, the total sampling area ranging from the Pyrenees to the Czech Republic. Allozyme electrophoresis of 21 (O. cacaliae) and 16 (O. speciosissima) loci revealed high genetic variability as expressed in a high percentage of polymorphic loci (only one monomorphic locus was found in each species) and high heterozygosities. No overall linkage disequilibrium was found in either species. Extensive heterozygote deficits were observed in several samples as reflected by high F IS -values and high overall inbreeding coefficients (F IT ) of 0.349 (O. cacaliae) and 0.503 (O. speciosissima). The overall inbreeding coefficient was mainly attributable to within-population differentiation. The high heterozygote deficits are explained by a combination of inbreeding resulting in kinship groups and a sampling effect over several such kinship groups. No explanation of the observed patterns could be found in the host plant use or altitudinal location of the samples. For O. cacaliae, isolation by distance was found, but not for O. speciosissima. Gene flow estimates were in the range of Nm = 0.8 to 1.5.

Phylogeography of the montane caddisfly Drusus discolor: evidence for multiple refugia and periglacial survival

“…Clear patterns of genetic population structuring due to limited gene flow are common in insects inhabiting high montane regions, or sky islands (Knoll et al 1996;Knoll & Rowell-Rahier 1998;Knowles 2001;Mardulyn 2001). Our data additionally show a high level of genetic differentiation between mountain range populations, whereas genetic variability within mountain ranges is low in Drusus discolor.…”

Geographic Variation in Advertisement Calls in a Tree Frog Species: Gene Flow and Selection Hypotheses

“…We doubt that lack of correlation between geographic distance and call characters was a result of inadequate sampling, as there was a significant IBD effect on the mitochondrial gene. The effect of IBD might have differently influenced call characters and mitochondrial COI sequences in an uncorrelated manner [49] , [50] . This conflicting result may also indicate that some selective factors may still be operating on call characters of H. japonica in Korea.…”

Positive Frequency-Dependent Selection on Warning Color in Alpine Leaf Beetles

“…Oreina communities are susceptible to vary geographically in the species present because of variation in the host plants available, and as a result of stochastic effects of their limited dispersal ability, the isolated nature of their habitats, and the fact that the entire region was subjected to repeated extinction and recolonization during Quaternary glacial cycles (Hewitt 2004;Margraf et al 2007). Local adaptation of populations towards the fitness peak formed by the predominant color of the community could therefore be responsible for the observation that several species show great variation in coloration across their distribution (Kippenberg 1994;Knoll and Rowell-Rahier 1998). In contrast, this form of frequency-dependent predation should eliminate within-population polymorphism because it generates strong purifying selection.…”