Abstracts (first author)
From Africa and back again: biogeography and differentiation of a specialist west-Mediterranean butterfly in a fragmented glacial refuge
The Mediterranean area is well known for retaining and generating biodiversity during climate and habitat shifts taking place since the end of the Miocene. This important biodiversity hotspot is both the source and the result of a complex process of differentiation and interaction between evolving lineages and their changing environment. However, regarding stationary Mediterranean specialists, which are expected to benefit and expand northwards with climate amelioration, little is still known. Using the butterfly Euchloe tagis, an Atlanto-Mediterranean ecological specialist with a fragmented and restricted distribution, this study attempts at answering pertinent biogeographic aspects on the species and its interaction with the changing ecosystem. We sequenced a 599bp barcode region fragment of the COI gene from all major populations to better understand current its genetic patterns and evolutionary history. Main results suggest an origin in North Africa, from where the sister species Euchloe pechi is endemic. While one of the Moroccan populations diverged earlier from the remaining stock, all remaining are more closely related despite the existence of differentiated major mitochondrial lineages. It seems that Iberia has played a pivotal role in the generation of diversity in this species: two consistent genetic clusters are partly sympatric whereas French and Italian populations are considerably different. The second Moroccan population from the Rif Mountains shows little segregation from French samples and this issue is discussed on a phylogeographic framework supported by molecular-clock analysis. This pattern suggests this species experienced polycentric refugia during climate cycles, leading to such genetic structure and a putative re-colonization of Africa. Moreover, the neutral genetic pattern reported in this study challenges current taxonomy based on morphological differentiation and suggests a more complex evolution of this species.
Comparative phylogeography and genetic population structure of two butterfly species from the Iberian Peninsula
The Iberian Peninsula is recognized as one of the most important refugia for temperate species during the cyclic climatic changes of the Plio-Pleistocene glacial periods. Mountainous regions within these refugia areas are also believed to retain high levels of endemism and genetic diversity due to the easily tracked suitable habitats by upward-downward movements. Here we examine population genetic structure, phylogeographic and demographic patterns of Lycaena bleusei, a butterfly species endemic to the Central Iberian Mountain System and contrast this to the patterns found for a congeneric widespread species, also occurring in the Iberian Peninsula, Lycaena tityrus. We use two molecular markers to understand if there is congruency in their evolutionary histories or, conversely, if different evolutionary drivers may have shaped these species differently. We find that the two species, which exhibit similar dispersal abilities and ecological requirements, show different demographic and genetic patterns. We hypothesize that these differences are due to the evolutionary forces acting on species that contracted to southern refugia during the Pleistocene and that, ultimately, drove to population differentiation and speciation. We also find evidence for hybridization events between these two species, with L. bleusei males coming in contact with L. tityrus females on a secondary contact zone described here for the first time.