Evolutionary genomics of speciation and species differences

We study the evolutionary genomics of species barriers in several model plant groups, including ecologically important species of the ‘model tree’ genera Populus (poplars, aspens, cottonwoods) and Salix (willows), or the ´evo-devo´ model plant group Antirrhinum (snapdragons). Thus far, we have been able to advance this research furthest in the two ecologically divergent Eurasian poplar species Populus alba (White poplar) and P. tremula (European aspen). The former is a foundation species in flood-plain forests and the latter is an upland pioneer. Numerous ecological differences separate these species, including divergent abiotic tolerances (flooding, drought), biotic tolerances (defence against herbivores and pathogens), and flowering phenology. Candidate traits and genes relevant to these ecological traits have been identified, using whole genome sequencing (WGS) and complementary approaches aimed at specific genetic pathways. 

Much of our research on Populus has made use of natural hybrid zones for identifying genomic regions and candidate gene variants that cross the species barrier more or less frequently than expected under neutrality. We have used poplar hybrid zones  to study the genomic basis of species isolation and the potential for adaptive introgression across species boundaries using high throughput sequencing. Ongoing work extends this research to the entire species complex of white poplars in Europe and Asia, with special emphasis on understanding the genetic basis of traits involved in response to abiotic stresses, herbivory, pathogen attack, and other biotic interactions.

Genetics of adaptation to new environments

We study the genetics of adaptation to new environments in ecologically important, outcrossing plant species. Understanding the genomic basis of local adaptation is crucial for assessing the conditions under which organisms will be likely to adapt successfully in situ to global (e.g. climate) change. We started with Populus tremula and P. alba because local populations of these species are close to random mating, which allows us to make efficient use of the tools of population genomics for studying the signature of local adaptation. Ongoing work uses whole genome sequencing to identify genes and markers that are more divergent between local populations than expected under neutrality, and markers with unusual signatures of diversity in particular populations, indicative of ‘selective sweeps’. An important goal of this work is to understand how species´ biogeographic history affects the adaptively important genetic variation now available for adaptation to environmental change.

Evolution of diversity in highly structured and species-rich environments

We are engaged in ecological & evolutionary genomics work in several biodiversity ´hot spots´ around the world, including  the Neotropics, Southern Africa, and Southeast Asia. Common themes of these projects are (1) the goal to understand the evolution and maintenance of genomic diversity in highly structured and species-rich environments, (2) the transfer of knowledge and techniques from model systems such as Populus to highly speciose organismal groups. This research is carried out in collaboration and has thus far been supported by the Brazilian CNPq and CAPES, the Swiss SNF, the Portuguese FCT, and the Chinese Academy of Sciences.

Our current focus of this research is on species diversification in neotropical mountains, using bromeliads (Bromeliaceae) and palms (Arecaceae) as exemplary model plant radiations. Within an established international research consortium, we use whole genome and targeted resequencing approaches to study the origin and maintenance of biological diversity in these groups across a wide range of spatial, temporal, and taxonomic scales. Our overarching goal is to combine data from population genomics, phylogenomics, and ecology to yield a comprehensive understanding of the drivers and limits of neotropical radiations with unprecedented breath and depth. In bromeliads, this research benefits greatly from locally available living collections and long-standing expertise of our extended group in the taxonomy, systematics, evolutionary biology, and population genetics of this ecologically important ´text book´plant radiation.

updated on Sep 2016