Perspectives on the use of landscape genetics to detect genetic adaptive variation in the field

Understanding the genetic basis of species adaptation in the context of global change poses one of the greatest challenges of this century. Although we have begun to understand the molecular basis of adaptation in those species for which whole genome sequences are available, the molecular basis of adaptation is still poorly understood for most non-model species. In this paper, we outline major challenges and future research directions for correlating environmental factors with molecular markers to identify adaptive genetic variation, and point to research gaps in the application of landscape genetics to real-world problems arising from global change, such as the ability of organisms to adapt over rapid time scales. High throughput sequencing generates vast quantities of molecular data to address the challenge of studying adaptive genetic variation in non-model species. Here we suggest that improvements in the sampling design should consider spatial dependence among sampled individuals. Then, we describe available statistical approaches for integrating spatial dependence into landscape analyses of adaptive genetic variation

Pleistocene survival in three Mediterranean refugia: origin and diversification of the Italian endemic Euphorbia gasparrinii from the E. verrucosa alliance (Euphorbiaceae)

Applying molecular (AFLP and sequences of nuclear ribosomal ITS), karyological (relative genome size estimations and chromosome counts) and morphometric methods we explored the origin of Italian endemic Euphorbia gasparrinii. AFLP data inferred three phylogeographic groups corresponding to Balkan-Central European-northern Italian E. verrucosa, Italian E. gasparrinii and Iberian E. flavicoma. Genetic differentiation among the three species is weak, suggesting their relatively recent divergence. Karyological analyses revealed that populations of E. gasparrinii have 2n = 16 chromosomes, whereas the other two taxa have 2n = 14. This, with weak genetic differentiation and allopatric distribution, supports its recognition as an independent species, despite its weak morphological differentiation. Our study also revealed multiple autopolyploidization events within all three taxa. Contrary to the diploid Apennine populations, the single currently known Sicilian population of E. gasparrinii is tetraploid. It is critically endangered, as the Sicilian distribution has decreased significantly during the past century. Our study underlines the importance of southern European peninsulas as refugial areas during the Pleistocene and provides additional evidence that Mediterranean high mountain plants are suffering severe range contractions due to climate warming

Long neglected diversity in the Accursed Mountains (western Balkan Peninsula): Ranunculus bertisceus is a genetically and morphologically divergent new species

Southern European mountain ranges have long been recognized as important hotspots of genetic diversity and areas of high endemism. Reflecting the geographical complexity of these mountain ranges, many European high-mountain species exhibit disjunctions on a variety of geographical scales. One of the long-neglected, poorly investigated and unresolved taxonomic problems concerns Apennine and Balkan members of Ranunculus section Leucoranunculus. According to the most recent taxonomic treatment, this section includes Ranunculus crenatus, distributed predominantly in siliceous massifs of the Carpathians and the Balkan Peninsula, but with a highly disjunct partial distribution area in the eastern Alps, and Ranunculus magellensis, which is usually considered a calcicolous endemic of the central Apennines. However, R. magellensis has also been suggested to occur in the carbonate ranges of the Albanian Alps, which would render this species amphi-Adriatic. We used complementary molecular methods (sequences of the nuclear ribosomal ITS region and of plastid DNA and amplified fragment length polymorphisms), relative genome size measurements and morphometric analyses to elucidate the relationships in Ranunculus section Leucoranunculus. Specifically, we asked if it comprises only a single, widespread and morphologically variable species or several narrowly distributed species with constant morphology. The results of our study showed that populations growing on limestone in the Albanian Alps in northern Albania and southern Montenegro are divergent and should be recognized as a new species, Ranunculus bertisceus Kuzmanović, D.Lakušić, Frajman & Schönsw., sp. nov. These populations differ not only from R. crenatus s.s., which grows on silicates, but also from the calcicolous Apennine endemic R. magellensis. The eastern Alpine populations of R. crenatus, which occur very locally in the Niedere Tauern area, originate from immigration from the Bosnian mountains

Long-distance plant dispersal to North Atlantic islands: colonization routes and founder effect

Long-distance dispersal (LDD) processes influence the founder effect on islands.We use genetic data for 25 Atlantic species and similarities among regional floras to analyse colonization, and test whether the genetic founder effect on five islands is associated with dispersal distance, island size and species traits. Most species colonized postglacially via multiple dispersal events from several source regions situated 280 to .3000 km away, and often not from the closest ones. A strong founder effect was observed for insect-pollinated mixed maters, and it increased with dispersal distance and decreased with island size in accordance with the theory of island biogeography. Only a minor founder effect was observed for wind-pollinated outcrossing species. Colonization patterns were largely congruent, indicating that despite the importance of stochasticity, LDD is mainly determined by common factors, probably dispersal vectors. Our findings caution against a priori assuming a single, close source region in biogeographic analyses. Amplified fragment length polymorphism (AFLP); dispersal vector; founder effect; genetic diversity; islands; long-distance dispersal (LDD); postglacial; species traits