Understanding evolution

Understanding evolution

Our scientists use collections and cutting-edge techniques to answer fundamental questions on the origin of biodiversity: What are species? How do species arise? How can we explain variation in biodiversity across space and time?

Research at Meise Botanic Garden spans the continuum of population genetics and macroevolution of plants, fungi and algae. Our researchers are at the forefront of new methods in population genetic and phylogenetic analysis. The results of our work are used to better understand biogeographic history, macroevolutionary patterns, and evolution of traits, to inform conservation, and enable reliable identifications.

Plant speciation processes: phylogeographic history, ecological specialization and reproductive isolation in Silene nutans

In collaboration with the University of Lille (France), this project aims at understanding the evolution and mechanisms leading to speciation in a context of phylogeographic history of Silene nutans (Caryophyllaceae), focusing on two processes: acquisition of reproductive isolation and ecological specialization. Using the evolutionary information provided by previous phylogeographic studies, we investigate the existence of pre- and post-zygotic reproductive barriers to hybridization. Reproductive isolation mechanisms are studied using a genomic approach and in progenies from cross pollinations between these lineages, and possible selective edaphic and biotic factors driving speciation.

For more information visit the page of Fabienne Van Rossum.

Genetic tools for implementing conservation and restoration of rare and endangered species

Genetic and genomic tools (quantification of genetic diversity and structure of populations using plastid and nuclear DNA markers, and quantitative traits measurements to estimate plant fitness) are essential in the setting up of appropriate conservation management strategies. We use these tools: (1) to attempt to elucidate the taxonomic status of the obscure endemic Sempervivum funckii var. aqualiense; (2) to delineate evolutionary and taxonomic units to preserve (e.g. Silene nutans); and (3) to estimate the genetic diversity and structure (and so the evolutionary potential) of natural and translocated populations of critically endangered species (e.g. Arnica montana, Campanula glomerata, Dianthus deltoides, Helichrysum arenarium) in order to propose appropriate measures for genetic restoration and rescue, to optimize the translocation preparation and to evaluate by a genetic monitoring the success of seed sowing and plug plant translocations.

For more information visit the page of Fabienne Van Rossum.

Population genetics and evolution of African trees

Current logging in tropical rainforests is mainly focused on a selected number of tree species causing populations of these species to be under very high pressure. As a result, knowledge on the population genetic structure of these valuable timber species as well as their evolutionary relationship to other forest taxa is extremely valuable since several African rainforest trees are critically endangered. We analyse population genetics structure and genetic diversity of important timber species, including Prioria balsamifera, P. oxyphylla, Staudtia kamerunensis, and Scorodophloeus zenkeri using target capture sequencing and microsatellite analysis. Complementary, genome skimming by shotgun sequencing will be applied on multiple tropical African tree species from our herbarium to construct a DNA reference database, which will be used to quickly identify logged or collected specimens at species level.

For more information visit the page of Steven Janssens and Samuel Vanden Abeele.

Evolution of plant functional traits

We test hypotheses about the evolution of functional traits (e.g. seed size, stomatal density, nectar chemistry etc.) using a combination of well resolved phylogenies, functional trait values and comparative statistical methods. These studies can learn us about the driving factors behind the evolution of plant from a trait perspective. For more information information visit the page of Filip Vandelook.

Phylogenetics, biogeography and evolution of Rubiaceae

Our large herbarium collections, elaborate DNA collections and sizeable living collections allow us to address questions on phylogenetics, biogeography and evolution of Rubiaceae. Our expertise includes molecular phylogenetics, population genetics, dating, biogeographical analyses, morphology and anatomy, ontogeny, taxonomic work at species level as well as a good knowledge of the diversity of Rubiaceae in Africa and Madagascar.

For more information visit the page of Steven Janssens and Petra De Block.

Island plant radiations in Southwestern Indian Ocean hotspot of biodiversity

Since Darwin, islands are considered by scientists as natural laboratories for studying patterns and processes in evolutionary biology. Indeed, insular systems (e.g., oceanic archipelago) are often seen as replicated “natural experiments” with variations in factors controlling the distribution, the characters, and the diversity of species. Home of ca. 13,000 plant species (89 % endemic), the biodiversity hotspot of Madagascar and the Indian Ocean islands (or southwestern Indian Ocean region, hereafter SWIO) is rich of “natural replicates” (i.e., islands) with different geology, origin, and nature. Therefore, this region constitutes a suitable model region to study plant radiations in insular environments. One approach to describe and test evolutionary scenarios that have shaped the plant diversity in SWIO includes comparative phylogenetic methods. However, those approaches need both a solid taxonomy sustained by a fully resolved and strongly supported phylogenetic framework. However, such prerequisites are often missing for most of groups occurring in Madagascar and Indian Ocean Islands.

Researchers of Meise Botanic Garden use herbarium collections, phylogenomic tools and comparative methods to disentangle the evolutionary history and the taxonomy of several successful plant radiations that have occurred in SWIO. For example, we are involved in several projects focused on Malvales and Rubiaceae. The final objective fits in obtaining a better picture for the evolutionary scenario that has shaped the diversity in the SWIO region.

For more information visit the page of Timothée Le Péchon.

Fungal phylogeny and evolution

Despite their essential role in the environment, the number of described fungal species (ca. 120,000) is still very low compared to recent estimates of the fungal diversity (2.2 to 3.8 million species). Moreover, recent studies have reported that only about approx. 35,000 correctly identified fungal species are represented by DNA sequences in public databases. Studies on the evolutionary history and biogeographical patterns of fungi are still in their infancy. Several factors can explain the slow pace of progress, including taxonomical difficulties due to morphological convergence and cryptic diversity, the limited fossil records, and poor sampling in many regions of the world.

By integrating different species concept approaches, and by using phylogenetic techniques, we investigate speciation mechanisms, evolutionary relationships and historical biogeography of several fungal groups encompassing a diversity of ecological functions (biomass turnover, plant pathogens-regulation, plant growth) and representing different biological strategies of reproduction (annual, perennial), and nutrition (wood-decay, tree parasite, symbiotic ectomycorrhizae). Our studies improve our understanding of “what is a species” and re-evaluate “a posteriori” the diagnostic criteria, thus untangling several taxonomical controversies and progressing in the comprehension of the evolutionary history of this ancient and diverse group of organisms.

For more information visit the page of Mario Amalfi and Olivier Raspé

Phylogenetics and co-evolution in lichens

Symbiosis, whether it concerns parasitism, commensalism or mutualism, is the result of long and complex coevolution processes and constitutes an important field of study in both fundamental (ecology, conservation biology, phylogeny) and applied research (biological pest control, biotechnology, medicine). Among mutualistic relations, lichens are outstanding study organism, because these chimerical entities have completely other characteristics than the composing organisms: the fungus (mycobiont) and the photobiont, which is either a green alga (mainly trentepohlioid, chlorococcoid or trebouxioid) or a cyanobacterium.  Lichenization appeared several times independently in the fungal kingdom, in both Ascomycota and Basidiomycota, and was successful leading to nearly 20,000 accepted species. Recent studies suggest more complex symbiotic relations involving other microorganisms.

We aim at resolving the origin of lichenization and the evolution of the fungus lifestyles in different classes of fungi, at refining different taxonomic entities, at resolving the relations between anamorphic and teleomorphic taxa, and at understanding the mechanisms involved in the type of reproduction strategy in lichenized fungi.

For more information visit the page of Damien Ertz.

Evolution, diversification and historical biogeography of marine macroalgae

By combining genetic, macroecological and biogeographical data, we explore the historical processes by which seaweed species arise, diverge ecologically, and come to occupy different habitats and geographic regions. We focus on groups that have been well sampled throughout their geographical range, including the green algal genus Bryopsis, the red algal genus Portieria and the brown algal order Dictyotales. For more information visit the page of Frederik Leliaert.

Deep phylogeny of the green algae

Accurate phylogenetic reconstruction of an ancient group like the green plants (Viridiplantae) requires rich taxon and gene sampling, and accurate phylogenetic models. We aim to resolve deep phylogenetic relationships in the green plant lineage using multi-gene and genome scale data sets. We use these phylogenies to reconstruct key evolutionary events, such as transitions to benthic marine environments, and the evolution of macroscopic growth, enabling the interpretation of the ecological and evolutionary context of modern green seaweed origins. For more information visit the page of Frederik Leliaert.

Phylogenetics, biogeography and evolution of Balsaminaceae

For more information visit the page of Steven Janssens.

Evolutionary and biogeographical history of Antarctic diatoms

For more information visit the page of Bart Van de Vijver.