Colonization of the Aeolian Islands byPimelia rugulosa rugulosaGermar, 1824 (Coleoptera: Tenebrionidae) inferred from the genetic structure of populations: geological and environmental relations

The effects of island forest restoration on open habitat specialists: the endangered weevilHadramphus spinipennisBroun and its host-plantAciphylla dieffenbachiiKirk

Human alteration of islands has made restoration a key part of conservation management. As islands are restored to their original state, species interactions change and some populations may be impacted. In this study we examine the coxella weevil, (Hadramphus spinipennis Broun) and its host-plant Dieffenbach’s speargrass (Aciphylla dieffenbachii Kirk), which are both open habitat specialists with populations on Mangere and Rangatira Islands, Chathams, New Zealand. Both of these islands were heavily impacted by the introduction of livestock; the majority of the forest was removed and the weevil populations declined due to the palatability of their host-plant to livestock. An intensive reforestation program was established on both islands over 50 years ago but the potential impacts of this restoration project on the already endangered H. spinipennis are poorly understood. We combined genetic and population data from 1995 and 2010–2011 to determine the health and status of these species on both islands. There was some genetic variation between the weevil populations on each island but little variation within the species as a whole. The interactions between the weevil and its host-plant populations appear to remain intact on Mangere, despite forest regeneration. A decline in weevils and host-plant on Rangatira does not appear to be caused by canopy regrowth. We recommend that (1) these populations be monitored for ongoing effects of long-term reforestation, (2) the cause of the decline on Rangatira be investigated, and (3) the two populations of weevils be conserved as separate evolutionarily significant units.

A geographic mosaic of evolutionary lineages within the insular endemic newt Euproctus montanus

Islands are hotspots of biodiversity, with a disproportionately high fraction of endemic lineages, often of ancient origin. Nevertheless, intra-island phylogeographies are surprisingly scarce, leading to a scanty knowledge about the microevolutionary processes induced on island populations by Plio-Pleistocene climatic oscillations, and the manner in which these processes contributed to shape their current genetic diversity. We investigated the phylogeography, historical demography and species distribution models of the Corsican endemic newt Euproctus montanus (north-western Mediterranean). As for many island endemics, the continuous distribution of E. montanus throughout its range has hitherto been considered as evidence for a single large population, a belief that also guided the species' categorization for conservation purposes. Instead, we found a geographic mosaic of ancient evolutionary lineages, with five main clades of likely Pliocene origin (2.6-5.8 My), all but one restricted to northern Corsica. Moreover, the copresence between main lineages in the same population was limited to a single case. As also suggested by growing literature on intra-island phylogeographic variation, it seems that the extensive use of simplifying assumption on the population structure and historical demography of island populations--both in theoretical and applicative studies--should be carefully reconsidered, a claim that is well exemplified by the case presented here.

Phylogeography reveals routes of colonization of the bark beetle Dendroctonus approximatus Dietz in Mexico

We used mitochondrial DNA (mtDNA) sequence data and allele frequencies at eight microsatellite loci to examine the population genetic structure, estimate the divergence times of distinct lineages, and infer patterns associated with host colonization in populations of the bark beetle Dendroctonus approximatus in Mexico. Two haplotype groups were identified using mtDNA sequences in 71 individuals from 15 populations. The first group was distributed in the Sierra Madre Occidental (SMOc, Western Mexico), with some populations in the Faja Volcánica Transmexicana (Central Mexico), and the second was found in the Sierra Madre Oriental (SMOr, Eastern Mexico), with populations in the Sierra Madre del Sur (Southern Mexico). The estimated split between groups occurred in the late Pleistocene, around 0.195 Mya. Microsatellite allele frequencies revealed high genetic differentiation between pairwise populations, and genetic differentiation values indicated a genetic structure of isolation by distance. Both mtDNA sequence data and microsatellite allele frequencies indicated that D. approximatus had two independent colonization routes in Mexico, one through the SMOc and another along the SMOr. The widespread geographic distribution of D. approximatus in Mexico follows a model of population range expansion of two haplotype groups in which gene flow is restricted by the geographic separation between hosts imposed by physical barriers between populations.