Abstract: Abstract Aim Despite an improved understanding of Southern Hemisphere plant biogeography, the origins and evolution of sub?Antarctic floras remain poorly studied. Here, we investigate the historical biogeography of sub?Antarctic representatives of the genus Ranunculus. We aimed to establish when and from where the sub?Antarctic ranunculi originated as well as to examine the extent to which ecomorphological traits explain contemporary biogeographical patterns. Location Southern temperate and sub?Antarctic zones. Methods We first estimated a dated phylogeny for Ranunculus using combined chloroplast and nuclear data for 53 accessions; divergence times were inferred based on three temporal calibrations. We then used non?parametric multidimensional scaling to evaluate the ecomorphological diversity of 67 austral ranunculi representing a combination of sub?Antarctic species and those restricted to lower latitude landmasses. Results Phylogenetic analyses indicated that several Ranunculus lineages have colonized the sub?Antarctic islands. Divergence time estimates suggest recent arrival from source areas in Australia, New Zealand or South America. Species exhibiting two distinct ecomorphological trait combinations occur in both sub?Antarctic and lower latitude habitats; the proportions of each combination differed significantly between these areas. Main conclusions Ranunculus has colonized the sub?Antarctic on several occasions, most often arriving from the lower latitude landmasses prior to the Last Glacial Maximum. Taken together our analyses suggest that chance effects are likely to have influenced species arrival. However, following arrival trait?environment interactions appear to have been important for the subsequent establishment and persistence of ranunculi in sub?Antarctic habitats.

Abstract: The genus Dicrostonyx (the collared lemming) is undoubtedly the small mammal best adapted to the extreme conditions of the arctic environment. The Palearctic collared lemming has been described in numerous European Late Pleistocene localities up to south of France and Croatia. This species experienced climate-driven changes through time, changes mainly observed as repetitive pulses of pan-continental migration, and it thus became a typical indicator of glacial conditions. Using geometric morphometrics on molars, we evaluate the shape changes occurring during the last 100 ky over some dispersal events in Western Europe. The results point out that Dicrostonyx torquatus has a large intra-population variation with a homogenous morphology, regardless of the origin of the individuals. A temporal trend leading to a more complex tooth with a differentiated anterior loop on the first lower molar was observed. An additional effect of the distance from the core populations was also described with a more peculiar shape for the most western populations of France. These temporal and geographical trends might relate to the different migratory pulses documented from ancient DNA haplotypes.