Our group is currently working on the following projects:

Heterozygosity and fitness in fur seals

Pinnipeds are challenging to study as they are semi-aquatic, breed in remote and crowded colonies, and can be highly aggressive.  Fortunately, a scaffold walkway above a colony of Antarctic fur seals (Arctocephalus gazella) at Bird Island, South Georgia, allows all of the animals that come ashore to be studied with minimal disturbance.  In collaboration with Dr Jaume Forcada of the British Antarctic Survey, we have analysed genetic samples collected over two decades to discover the parentage of over a thousand pups.  A remarkable picture of breeding behaviour has emerged.  The most successful males appear to arrive first in the colony, stay for more days per season and come ashore for more seasons in total.  However, although the traditional picture is one in which males fight each other for access to females, the opposite appears to be true; males stay rooted to the spot while females appear to actively choose their partners.  We have also shown that heterozygosity correlates with virtually every male fitness trait measurable, including territory-holding ability, body size, reproductive success and even attractiveness.  More recently, we found that increasingly frequent adverse climactic events correlated with low food availability have led to profound phenotypic changes in the population, including an 8% decline in pup birth weight since the mid 1980s.  In parallel, average breeding female heterozygosity has increased by 17% over the past two decades, consistent with a temporal increase in the strength of viability selection on homozygous offspring.  We are now using a high-density single nucleotide polymorphism array to explore this phenomenon in greater detail.
Funded by: the DFG

Niche choice and conformance in fur seals

Niche choice and niche conformance are key mechanisms that alter the match between an individual and its environment, resulting in individualised niches.  However, while there is evidence for short-term fitness consequences of individualised niches, little is known about their long-term role.  Two major mechanisms may underlie how individualized niches are established in the longer term: gene-by-environment interactions and epigenetic regulation.  Together with Dr Jaume Forcada and Prof Toni Gossmann, we are investigating both of these mechanisms using a rich and exceptionally detailed long-term study of Antarctic fur seals.
Funded by:  the DFG (SFB, TRR 212, NC³)

Pinniped population genetics

We also work collaboratively on a variety of other pinniped species, including grey seals (Halichoerus grypus), South American fur seals (Arctocephalus australis), Southern sea lions (Otaria flavescens), Northern elephant seals (Mirounga angustirostris), Southern elephant seals (Mirounga leonina) and Steller’s sea lions (Eumetopias jubatus). Many of these projects are using molecular genetic approaches to shed light on population structure and demographic histories, both of which may have important implications for conservation.  For example, our work on Steller’s sea lions revealed a clear phylogenetic break within the range of this threatened ‘flagship’ species, in support of previous mitochondrial studies revealing two discrete stocks, and in line with the observation that two stocks show opposite growth trajectories.

Sea lion speciation genomics

One hundred and fifty years after Charles Darwin’s seminal work On the Origin of Species, the quest for the mechanistic underpinnings of speciation has begun in earnest.  Among the most promising systems to reveal the evolutionary processes that control adaptation and govern the early steps of speciation are evolutionary young lineages diverging along strong environmental gradients.  In particular, marine species provide ideal systems in which to test whether ecologically divergent selection in the absence of physical barriers to gene flow can lead to heterogeneous genomic divergence.  Sea lions from the Galápagos provide just such a system.  The species has a tiny geographic range relative to its dispersal capability but occupies a steep environmental cline between the nutrient-rich grounds around the young western islands and the islands on the shallow central shelf of the archipelago.  These environmental contrasts translate into marked differences in morphology, diet and the underlying genetics.  In collaboration with Prof Jochen Wolf, we are using whole-genome resequencing to quantify patterns of genomic divergence at base-pair resolution between ecologically and genetically divergent sea lion populations.
Funded by: the DFG

Olfactory communication in pinnipeds

Olfactory communication underpins virtually all aspects vertebrate social life, from mother-offspring communication through kin recognition to mate choice. In particular, odour seems to be an important pathway for signalling complex information about an individual’s genetic makeup, such as heterozygosity and relatedness. However, the extreme complexity of vertebrate odours has largely precluded a mechanistic understanding of the link between odour and genotype.  Antarctic fur seals provide an ideal model system for studying olfactory communication in a free-ranging marine mammal. In this species, olfaction is important for the close-range recognition of pups and breeding females also show mate choice for partners who are heterozygous and unrelated, implying that genotype could be encoded in scent. Together with Prof Barbara Caspers, we are combining gas chromatography-mass spectrometry (GC-MS) with microbiome sequencing and genetic analysis to shed light on the molecular mechanisms underlying chemical communication.

The costs and benefits of inbreeding

Although inbreeding is usually detrimental to fitness, theory predicts that it could have a substantial positive effect on inclusive fitness by increasing the benefits of cooperation.  In collaboration with Prof Mike Cant and Dr Hazel Nichols, we are exploring the causes and consequences of inbreeding using rich, multigenerational data from a long-term study of a cooperatively breeding mammal, the banded mongoose (Mungos mungo).
Funded by: the DFG

Sexual trait expression in black grouse

Since Darwin first coined the term “sexual selection” to explain the evolution of exaggerated male traits, we have come to understand the complex interrelationships among these traits, the information they encode and the life histories of the animals they are embedded into. Sexual selection is built on the idea that individual quality is signaled by the expression of these traits, yet a clear mechanistic understanding of the genetic architectures of sexual traits and the mechanisms regulating sexual trait expression remains elusive. Together with Dr Carl Soulsbury and Prof Kees van Oers, we are combining the genomic inference of inbreeding with genome-wide methylation analysis to investigate the genetic and epigenetic mechanisms affecting sexual trait expression and reproductive success in a classical lek model system, the black grouse, Lyrurus tetrix.
Funded by: the DFG

Shorebird ecology and conservation

Sex ratio biases are widespread in nature and represent a fundamental component of sexual selection.  They can also have a strong influence on population viability and persistence.  Small plovers (Charadrius spp.) exhibit diverse mating systems, ranging from monogamy to polygyny. Consequently, in collaboration with Prof Oliver Krüger, Prof Tamás Székely and Dr Nayden Chakarov, we are studying sympatric populations of three species in Madagascar, using a combination of molecular genetic and demographic modelling approaches, to identify the underlying factors that drive adult sex ratio variation.
Funded by: the DFG

Seascape genetics in the cold

The persistence of a species within a changing environment depends on a number of factors.  Arguably the most important of these is the ability of local populations to acclimate to changing conditions, but population genetic connectivity is also crucial as this determines the extent to which beneficial alleles can spread among populations.  However, the factors that affect genetic connectivity are still poorly understood, particularly in the marine realm where intrinsic factors such as life history may interact with multiple physical variables including ocean currents, sea bed topology and substrate type.  Together with Prof Lloyd Peck and Prof Melody Clark of the British Antarctic Survey, we are using an unusually large collection of samples of a brooding Antarctic marine mollusc Margarella antarctica to elucidate how various factors shape the population genetic structure of a dispersal-restricted marine invertebrate over multiple geographic scales, from hundreds of kilometres down to as little as one metre.   We will use a spatially explicit modelling framework incorporating genetic data from over a hundred locations on the Western Antarctic Peninsula, one of the fastest-warming regions of the planet.  There is an imperative to understand and predict how the endemic, slowly evolving, cold-adapted fauna of this region will cope with ongoing climate change.
Funded by:  the DFG

Phenotypic plasticity, local adaptation and climate change responses

One of the most topical questions in science and one of the issues of greatest concern to society is how life on earth will respond to climate change.  This is particularly important for species living in polar areas where the most rapid and profound changes are occurring.  However, predicting species responses requires a detailed understanding of the genetic basis of variation in individual fitness.  Our recent study in Nature has shown that climate change is exerting increasingly strong viability selection on an Antarctic fur seal population, specifically against relatively homozygous offspring.  However, it is actually marine invertebrates that are at the greatest risk under future climate change scenarios due to the warming and acidification of the World’s oceans.  Consequently, together with Prof Lloyd Peck and Prof Melody Clark of the British Antarctic Survey, we have begun to apply genomic tools to elucidate the mechanisms by which Antarctic marine invertebrates may respond to environmental change.  For example, we recently used reciprocal transplant experiments together with transcriptome sequencing to investigate the molecular basis of phenotypic plasticity in an Antarctic limpet, Nacella concinna.   We are also using a novel approach based on heated settlement panels to assess the in situ effects of warming on marine encrusting communities in polar seas.  We recently reported in Nature Communications that Antarctic encrusting communities fail to acclimate to 18 months of localised warming to either +1 °C or +2 °C above ambient temperature.
Funded by: Natural Environment Research Council

COMPOSES – COMparing Polar Ocean SoundscapES – investigating the influence of anthropogenic noise and changing sea ice conditions on the noise budgets and marine mammal communities of two polar regions

Sea ice loss in polar seas leads to increasing human activities in areas that were formerly blocked by sea ice. Activities such as tourism, oil- and gas-exploration, commercial shipping, and fishing activities introduce a significant amount of noise into these areas. In Arctic seas, noise pollution is already significant but the interpretation of acoustic fluctuations in anthropogenic noise-affected areas lacks reference information. By contrast, the soundscape of the Southern Ocean is considered relatively pristine (with little to no anthropogenic interference) and is emphasized as reference for intact soundscapes. Increasing noise levels can interfere with the communication and navigation of marine mammals. In particular, ice-bound marine mammals endemic to polar seas are vulnerable to continuing environmental change and can thus act as sentinels for ecosystem change. Furthermore, relatively little is known about how pinniped distributions relate to sea ice conditions. Up to 15 years of passive acoustic monitoring (PAM) data from several recording positions are available from two polar oceans with strongly differing underwater noise regimes: the virtually pristine Antarctic Weddell Sea and the anthropogenic noise affected Arctic Fram Strait. Together with Dr Ilse van Opzeeland, we will generate regional noise budgets for both polar basins comprising spatial and temporal variation in the energetic contributions of all significant abiotic, biotic and anthropogenic underwater sound sources. The outcome will constitute reference soundscape data that will contribute towards international efforts to map worldwide patterns of underwater sound. PAM data will be used to assess spatio-temporal patterns of ice-bound marine mammals in relation to different sea ice conditions (sea ice thickness, concentration, fraction of leads, etc.) and noise levels. Last but not least, we will use PAM data to investigate how noise and changing sea ice conditions influence acoustic marine mammal community patterns.

Demographic histories, deleterious mutations and inbreeding depression in pinnipeds

A substantial proportion of inbreeding depression is believed to result from recessive deleterious mutations that become homozygous in inbred individuals.  Accordingly, population genetic theory predicts that the strength and genetic architecture of inbreeding depression will depend on the total burden of deleterious mutations (“mutation load”) as well as on the relative frequencies of highly, moderately and weakly deleterious alleles.  In turn, the mutation load should be strongly influenced by historical population size changes such as bottlenecks, as small populations are expected to purge highly deleterious mutations more efficiently than large ones.  We are currently investigating the interplay between demography, detrimental mutations and inbreeding depression using advanced computational methods to infer genomic landscapes of deleterious variation across pinniped species with contrasting demographic histories.
Funded by:  the DFG

Population dynamics, dispersal and adaptation in Porcini mushrooms

Ectomycorrhizal fungi are critical components of terrestrial ecosystems that play essential roles in nutrient recycling. Consequently, there is a pressing need to study their population dynamics and life histories so as to better understand how ecosystems function and persist. In particular, we need to learn how these fungi disperse, colonise new habitats, persist, adapt to their hosts and, in the longer term, speciate.  Together with Prof Bill Amos, Dr Kanchon Dasmahapatra, Prof Bryn Dentinger, Dr. Fernando Martínez Peña, Dr.  Minou Nowrousian, Dr. Ulrike Damm and Prof. Thorunn Helgason we are studying the population genetics of the iconic edible mushroom, Boletus edulis, known variously as the penny bun, cèpe de Bordeaux, porcino or Steinpilz.  We are currently using microsatellites to genotype a large collection of B. edulis samples that have been systematically gathered from sites in Germany and the UK over the last ten years.  We hope to use whole-genome sequencing to unravel genome-wide patterns of divergence in relation to geography and host species.
Funded by: the DFG

Host-microbe interactions

Vertebrates are inhabited by vast numbers of microorganisms that are increasingly emerging as key players in their host’s biology and evolution. These microbial communities carry orders of magnitude more genes than their hosts and support functions that are not encoded in the host’s genome. Consequently, the microbiome is of fundamental importance to host function.  Together with Dr Jaume Forcada and Prof Michael Schloter, we are investigating the extrinsic and intrinsic drivers of the gut microbiome of Antarctic fur seal pups during the critical developmental time window between birth and nutritional independence, as well as how the gut microbiome influences growth and survival.
Funded by: the DFG

---

Collaborators

In alphabetical order

Prof Karina Acevedo-Whitehouse, Autonomous University of Queretaro, Mexico
Prof William Amos, University of Cambridge, UK
Dr Michelle Barbieri, National Oceanic and Atmospheric Administration, USA
Dr Alastair Baylis, Macquarie University, Sydney
Prof Pierre Boudry, Institut français de recherche pour l’exploitation de la mer, France
Prof Mike Cant, University of Exeter, UK
Prof Barbara Caspers, Bielefeld University, Germany
Dr Francisco Ceballos, Middle East Technical University, Turkey
Dr Nayden Chakarov, Bielefeld University, Germany
Dr Greg Charrier, Université de Bretagne Occidentale, France
Prof Melody Clark, British Antarctic Survey, UK
Dr Ulrike Damm, Senckenberg Museum of Natural History Görlitz, Germany
Dr Kanchon Dasmahapatra, University of York, UK
Prof Patrice David, Centre d’Ecologie Fonctionnelle et Evolutive, France
Dr Bryn Dentinger, Natural History Museum of Utah, USA
Dr Farnon Ellwood, University of the West of England, UK
Dr Jaume Forcada, British Antarctic Survey, UK
Dr Filippo Galimberti, Elephant seal research group, Italy
Prof Rob Garrott, Montana State University, USA
Dr Stephen Gaughran, Princeton University, USA
Dr Tom Gelatt, National Oceanic and Atmospheric Administration, USA
Dr Mike Goebel, National Oceaninc and Atmospheric Administration, USA
Dr Toni Gossmann, Bielefeld University, Germany
Dr Frances Gulland, UC Davis, USA
Prof Ken Halanych, Auburn University, USA
Prof Elizabeth Harper, Cambridge University, UK
Prof Thorunn Helgason, University of York, UK
Dr Alexandros Karamanlidis, ARCTUROS, Greece
Dr Marty Kardos, National Oceanic and Atmospheric Administration, USA
Dr Anastasia Klimova, Centro de Investigaciones Biológicas del Noroeste, Mexico
Prof Klaus-Peter Koepfli, George Mason University, USA
Prof Kit Kovacs, Norwegian Polar Institute, Norway
Prof Oliver Kruger, Bielefeld University, Germany
Prof Roland Langrock, Bielefeld University, Germany
Dr Kim Last, Scottish Association for Marine Science, UK
Dr Florian Leese, Duisburg-Essen University, Germany
Prof Tobias Lenz, Hamburg University, Germany
Dr Andy Lowther, Norwegian Polar Institute, Norway
Dr Christian Lydersen, Norwegian Polar Institute, Norway
Dr Aurelio Malo, Universidad de Alcalá, Spain, and Oxford University, UK
Dr Fernando Martínez Peña, Agrifood Research and Technology Centre of Aragón, Spain
Dr Frank Melzner, GEOMAR, Germany
Dr Kati Michalek, Scottish Association for Marine Science, UK
Prof Thomas Mock, University of East Anglia, UK
Prof Caroline Müller, Bielefeld University, Germany
Dr Hazel Nichols, Swansea University, UK
Dr Minou Nowrousian, Ruhr-University Bochum, Germany
Prof Morten Olsen, University of Copenhagen
Dr Ilse van Opzeeland, Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Germany
Prof Lloyd Peck, British Antarctic Survey, UK
Dr Paddy Pomeroy, University of St Andrews, UK
Dr Stacie Robinson, National Oceanic and Atmospheric Administration, USA
Dr Larissa Rosa de Oliveira, Universidade do Vale do Rio dos Sinos, Brazil
Prof Jay Rotella, Montana State University, USA
Dr Simona Sanvito, Elephant seal research group, Italy
Prof Michael Schloter, Technische Universität München, Germany
Prof Jon Slate, Sheffield University, UK
Dr Carl Soulsbury, University of Lincoln, UK
Dr Iain Staniland, British Antarctic Survey, UK
Dr Paul Sunnucks, Monash University, Australia
Prof Tamás Székely, University of Bath, UK
Prof Ralph Tiedemann, Potsdam University, Germany
Dr Constanza Toro-Valdivieso, Cambridge University, UK
Prof Fritz Trillmich, Bielefeld University, Germany
Dr Sean Twiss, Durham University, UK
Prof Kees van Oers, Netherlands Institute of Ecology and Wageningen University, the Netherlands
Dr Tom Wilding, Scottish Association for Marine Science, UK
Prof Mary Wisz, World Maritime University, Sweden
Prof Jochen Wolf, Ludwig Maximilian University of Munich, Germany
Prof Guojie Zhang, Zhejiang University, China
Dr Sama Zefania, University of Toliary, Madagascar