Shark’s and their relatives are distinctly unique compared to other vertebrates (including humans); they have an internal skeleton made entirely out of cartilage. It was presumed that cartilage was the ancestral condition among vertebrates based on the assumption that evolution would be driven toward the increased complexity of bone. However, recent fossil evidence disproves this assumption and reveals that the skeletal mineralisation shown in sharks (calcified cartilage) is an evolutionary innovation. Our understanding of calcified cartilage in sharks greatly lags behind that of the hard tissues in other vertebrates. Thus, the mechanisms behind cartilage calcification, how or whether this relates to bone, and our overall understanding of how hard tissues evolved in vertebrates is impacted. In this project, I will address this knowledge gap by examining the 3D histology of calcified cartilage in a wide range of both living and fossil sharks, using cutting-edge scanning methods. This holistic approach will cover 400 million years of cartilage evolution in sharks. The results of this project will be of importance across multiple scientific fields: advancing our understanding of the evolution of hard tissues in vertebrates, detailed 3D information on structural properties of calcified cartilage relevant to material engineering, and insight into calcification mechanisms relevant to medical research on cartilage disorders in humans. Naturalis is the perfect setting to conduct this research due to the vast collection of preserved sharks available for study, expertise in hard tissue histology, and active collaborations with medical researchers on cartilage disorders. It also offers a valuable platform for public outreach and skills training, such as in management and science communication. This project will provide a crucial stepping stone towards my aspiration to spearhead a research team focused on bridging research of both fossil and living animals.

By their own very nature, islands are natural laboratories where evolutionary outcomes seem to exceed the limits of imagination. Stubby and flightless birds, dwarf elephants and hippos, and giant mice are some of the bizarre examples. Those morphological modifications are not the result of random variation but are triggered by the specific ecological conditions of the islands (absence of terrestrial predators and low level of competition for food and space). In some occasions, these conditions do not lead to a particular shift in body size, but instead to a diversification event, resulting in a disparity of forms, such as the case of Darwin’s finches in Galapagos. The island of Crete (Greece) housed one such diversification, that of the enigmatic extinct Pleistocene deer. This genus (Candiacervus) evolved into eight species in six size groups, ranging from ~28 to ~245kg in body mass, in less than 1 million years. In CREDE I will explore this unusual disparity of body size in Cretan deer to understand the evolutionary mechanisms behind species radiations in mammals. Despite advances over the years in knowledge on this lineage, mainly focusing on dwarf or giant species, we know little about the factors underpinning this level of diversity. In CREDE I will employ my expertise in deer bone histology together with the novel application of 3D image analysis to examine bone microstructure of Cretan deer, and thus, obtain data about their life strategies (age at maturity, pace of growth, longevity). Moreover, the use of stable isotope will provide new integrative data on the ecological and dietary preferences of the different species. Finally, the combination of both approaches will shed light on diversification of mammal lineages on a macroevolutionary scale, presenting a comprehensive framework for interpreting mammalian evolution.

Mountain ranges support about 25% of all terrestrial species in the world and are hotspots of biodiversity and endemism with high conservation value. Despite mountains being among the most species-rich regions in Asia, they are one of the world's most fragile ecosystems due to habitat destruction and global climate change. Little is known about the historical (evolutionary) processes underpinning the unique plant diversity in Asian mountains. So far, most studies have focused on the Himalayan and Hengduan mountains, suggesting the elevated plant diversity results from the interaction between the Asian monsoon, geological history, and high immigration. However, existing studies in the Malay Archipelago suggest that species richness results from long-distance dispersal, immigration of lineages from local lowland ancestors, and complex geological history. Therefore, an integrated hypothesis-driven framework to test the relative importance of such drivers, including how functional traits innovations may have contributed to such radiations in the Asian mountains, is needed. The overarching aim of ASIA is to understand the evolutionary and biogeographical processes that govern the plant biodiversity of the tropical Asian mountains using the model plant group Rhododendron (heather family, or Ericaceae). This species-rich lineage is widely represented across almost all Asian biodiversity hotspots. The ASIA project will unravel the most important drivers of high plant diversity in Asian mountains by developing a well-resolved phylogenetic hypothesis using high-throughput sequencing technologies, biogeography, macroevolutionary models, geological history, and species ecology. ASIA will provide insights on the adaptability of a widespread plant clade and identify areas of high extant speciation rates and species richness with potential conservation applications.

Plants need light to grow. They use energy from sunlight to produce organic carbon. However, new findings – including my own work – now hint that up to 35% of all plant species can also obtain carbon from root-associated fungi when light availability is insufficient for growth. This calls into question much of what we thought we knew about how plants survive in the understory. The goal of this project is to determine the frequency and magnitude of this newly discovered form of ‘mixotrophy’ in our terrestrial ecosystems. I will achieve this exciting goal by working at the intersection of physiology, ecology, evolutionary and molecular biology. The vast majority of land plants transfer part of the organic carbon they produce by photosynthesis to root-associated ‘arbuscular mycorrhizal’ (AM) fungi, which help plants to take up nutrients and water from the soil. My previous findings demonstrate that this carbon can be subsequently taken up by rare non-green plants that tap into the same fungal network. This paved the way for the discovery of AM mixotrophy, in which common green plants take up carbon from AM fungi. However, the plant and fungal diversity involved in AM mixotrophy are unknown. Likewise, the environmental drivers that influence carbon uptake have never been measured, nor do we know about its evolution and geographic distribution. This is problematic because we are unable to quantify or understand the role of AM mixotrophy in our natural world. With field studies, laboratory experiments, and genetic screening of natural history collections, I will (1) identify AM mixotrophic plants and their habitats; (2) reveal environmental drivers that regulate carbon uptake; (3) expose fungal networks that sustain AM mixotrophs; and (4) measure the magnitude of AM mixotrophy across evolutionary and geographic scales. This will lead to a fundamental shift in our understanding of carbon uptake by plants, with profound effects for carbon cycling models and conservation.

Plant range size (geographic area occupied by a species), a key predictor of species’ extinction risk, is shaped by an interplay of evolutionary and ecological processes. Yet understanding how species’ biological traits interact with environmental factors to determine range size remains challenging. I hypothesize that plant trait flexibility (ability of traits to evolve to different trait states) and genome size (total DNA in cell’s nucleus) are two key biological factors that influence range size. Genome size imposes biophysical constraints on cell size and rate-related cellular traits (like cell cycle duration) impacting functional traits, e.g., photosynthetic rate, seed size. Large-genomed lineages with stronger biophysical constraints, are predicted to exhibit slower trait evolution compared to small-genomed lineages that, at the whole plant level, can impact where they can and cannot grow. High nutrient demand of large-genomes can also restrict species’ range size in nutrient-poor conditions. But it remains unclear how genome size’s effects on trait flexibility and diversification, influenced by abiotic factors, impact range size. I will address this knowledge gap by establishing a single quantitative framework using the widely distributed palm family (Arecaceae) as a model system. Palms possesses considerable genome size and trait diversity. A major methodological challenge of obtaining genome size data will be addressed by developing a method to predict genome size from leaf stomatal guard cell size. With a secondment and collaborating with a team of leading experts, I will expand my expertise on cytogenetics and evolution while acquiring new skills on ecological analyses, and develop my supervisory and leadership skills. Together, this project will lay the foundations for my future role as an independent group leader in plant evolutionary ecology with a focus on cytogenetics, to aid in conservation efforts.