Genetic diversity of a successful colonizer: isolated populations of Metrioptera roeselii regain variation at an unusually rapid rate

Abstract

Newly founded isolated populations need to overcome detrimental effects of low genetic diversity. The establishment success of a population may therefore depend on various mechanisms such as assortative mating, purging of deleterious alleles, creation of new mutations and/or repeated inflow of new genotypes to reduce the effects of inbreeding and further loss of genetic variation. We compared the level of genetic variation in introduced populations of an insect species (Metrioptera roeselii) far beyond its natural distribution with levels found in their respective founder populations and coupled the data with timing since establishment. This allowed us to analyze if the introduced populations showed signs of temporal changes in genetic variation and have made it possible to evaluate underlying mechanisms. For this, we used neutral genetic markers, seven microsatellite loci and a 676–bp-long sequence of the mtDNA COI gene. All tested indices (allelic richness, unbiased expected heterozygosity, effective size, haplotype diversity, and nucleotide diversity) except inbreeding coefficient had significantly higher values in populations within the founding populations inside the continuous area of the species distribution compared with the introduced populations. A logarithmic model showed a significant correlation of both allelic richness and unbiased expected heterozygosity with age of the isolated populations. Considering the species' inferred colonization history and likely introduction pathways, we suggest that multiple introductions are the main mechanism behind the temporal pattern observed. However, we argue that influences of assortative mating, directional selection, and effects of an exceptional high intrapopulation mutation rate may have impacts. The ability to regain genetic diversity at this level may be one of the main reasons why M. roeselii successfully continue to colonize northern Europe.

Genetic Diversity in Apple Fruit Moth Indicate Different Clusters in the Two Most Important Apple Growing Regions of Norway

“…conjugella analyses in the study showed a lower expected heterozygosity (He = 0.31), than was found in various insect species such as; Metrioptera roeselii "0.61" [60]; Leptomyrmex pallens "0.51" [61] and Cerambyx cerdo "0.63" [62]. However, the low expected heterozygosity was comparable to what was found in Plutella xylostella "0.35" [11], Anopheles nuneztovari (Culicidae) "0.34" [63], Glossina pallidipes "0.35" [64] and Bombus distinguendus "0.38" [65].…”

Genetic patterns reveal an old introduction event and dispersal limitations despite rapid distribution expansion

“…A recent study conducted by Kaňuch et al (2014) confirms our findings that both allelic richness and unbiased expected heterozygosity in isolated populations are correlated with population age. The lack of evidence of recent bottlenecks in any of the sampled populations and only slightly elevated levels of homozygosity indicate that immediate consequences of founder effects are not traceable (Luikart and Cornuet 1998).…”

“…It is likely that the populations at the range margin have not reached a demographic equilibrium yet and the genetic composition is expected to change with time as a consequence of genetic drift and gene flow (Bohonak 1999). Metrioptera roeseliis ability to regain genetic diversity appears to contribute to the species successful range expansion in northern Europe (Kaňuch et al 2014;Wissmann et al 2009). …”

“…Spatial and temporal variation of genetic structure arises as new populations are founded during range expansion events (Ibrahim et al 1996) and are shaped by migration of individuals between populations. The amount of genetic variation in newly founded populations depends on the number and origin of founding individuals and subsequent immigrants (Le Corre and Kremer 1998;Dlugosch and Parker 2008;Kaňuch et al 2014). Further, subsequent changes in genetic diversity within and among populations are influenced by the combined effects of the species dispersal behaviour and environmental factors.…”

Influence of invasion history on rapid morphological divergence across island populations of an exotic bird

“…Therefore, the ABC analysis suggested that these haplotypes likely originated from unsampled haplotypes within the eastern region of the source clade. While it is possible some of the haplotype variants could have emerged postintroduction through mutations (e.g., Agrawal & Wang, 2008; Kaňuch, Berggren, & Cassel‐Lundhagen, 2014; Vandepitte et al., 2014), such mutations would likely have added only a few new haplotypes and not likely the 74% new haplotypes we detected. With a substantial increase in sampling across the C.c.…”