Is there a host-associated molecular and morphological differentiation between sympatrically occurring individuals of the invasive leaf miner Cameraria ohridella?

Abstract

The leaf-miner moth Cameraria ohridella, a pest in Central Europe, causes severe damage to trees. Host-associated differentiation (HAD) for this species has been suggested previously based on the occurrence of a specific mitochondrial haplotype. We assessed genetic diversity and population structure for sympatrically occurring individuals collected in association with two host species, Ohio buckeye (Aesculus glabra) and horse chestnut (Ae. hippocastanum), using six microsatellite loci (SSR) and mtDNA sequences that encode parts of cytochrome oxidase I and II. To infer population structure and assign individuals to clusters, we employed Bayesian clustering. We further characterized the relationships between genetic distance and geographical distance (IBD) in analyzed samples. Although our results derived from the SSR loci analyses demonstrating that there was no population substructuring caused by the hosts, we found evidence of differences in wing size, which might be attributed to the quality of food resources available to larvae. The population structure with K = 2 cannot be interpreted as the result of IBD; rather, it reflects a population differentiation due to demographic or genetic processes (e.g., an origin of invaders). Although genetic diversity was relatively high (H e > 0.5), the population had a deficiency of heterozygotes (F IS > 0), which was most likely due to nonrandom mating and, possibly, a Wahlund effect. A star-like haplotype network and negative Tajima's D support the genetic effect of bottleneck followed by population expansion. Based on presumably neutral markers, we conclude that C. ohridella appeared to be a good model for studying evolution toward a generalist invasive species, rather than HAD.

Filogeografia molecular de >i<Thyrinteina arnobia>/i< (Lepidoptera: Geometridae) e >i<Gonipterus>/i< spp. (Coleoptera: Curculionidae) no Brasil

“…de T. arnobia não indica expansão populacional por efeito fundador uma vez que a rede de haplótipos não apresenta conformação "star-like" (onde existe um haplótipo central frequente com vários haplótipos menos frequentes partindo desse) e os testes de neutralidade não foram significativos. Assim, se sugere que as populações de T. arnobia passaram por efeitos de gargalho genético ou seleção recenteBUBAC & SPELLMAN, 2016;LAVAGNINI et al, 2015;MELOSIK et al, 2019). homogeneizar, entre as populações, os alelos fixados pela deriva genética ou a pela seleção natural promovida pelas condições bióticas e abióticas de cada região; as populações de T. arnobia que colonizam os cultivos de eucalipto já estavam.…”