Conservation biology of amphibians and reptiles in Switzerland

Supervised by Benedikt Schmidt

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Human activity is the cause of the ongoing biodiversity crisis. Our goal is to do research on the conservation biology of amphibians and reptiles because we would like to understand how conservation problems can be solved and thereby population declines halted or even reversed. In doing so, we would like to contribute to evidence-based conservation.

We study the dynamics and genetic structure of metapopulations that live in man-made landscapes. We would like to know how the metapopulations function and how they respond to changes in the landscape (e.g., is there an extinction debt?). We also study how conservation activity affects metapopulations. For example, we ask whether translocations are successful and whether we can increase dispersal rates in metapopulations. To address these questions, we must know how one can survey and monitor populations reliably. Therefore, we also study monitoring methods.

In addition, we study whether conservation action is successful. We select conservation actions and assess the success of these projects. We would like to know which conservation actions had the greatest positive effects on threatened species.

 

In collaboration with:

Linking behavioural, physiological and demographic responses to climate change

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Wandering albatross in flight (Photo: Mike Double)

There is an increasing body of evidence highlighting ecological alterations induced by climate change across the globe. Recently, Henri Weimerskirch and his colleagues showed that the wandering albatross (Diomedea exulans), a wide-ranging Sub-Antarctic seabird responded behaviourally, physiologically and demographically to changing wind patterns. This bird, which takes advantage of winds to reduce the flying cost, benefited from stronger winds and could cover more distance during foraging trips. Consequently, individuals increased in mass and had a higher reproductive success. Taking into consideration the potential changes in the environment is crucial to efficiently manage wild populations. Changes in the environment can be linked to demographic rates using behavioural and physiological traits as state variables. Using a trait-based model, we aim to investigate the effects of changes in foraging patterns and physiology, whether directly or indirectly induced by environmental changes, on the population dynamics of the wandering albatross. Quantifying movement and foraging patterns as a trait adds a new dimension to the existing trait-based modeling approaches. This model will enable us to (1) determine the most critical life history processes or pathways governing the population  persistence,  and  (2)  predict  population,  behavioural  and  phenotypic dynamics  under alternative climate change scenarios.

 

In collaboration with:

Hierarchical spatiotemporal modelling of distribution and abundance of Swiss breeding birds

Supervised by Dr. Marc Kéry (Swiss Ornithological Institute) & funded by Swiss National Science Foundation

vogelwarte

Spatiotemporal patterns in distribution and abundance are a fundamental theme in ecology and applied fields such as  biodiversity monitoring and conservation. However, two common problems are (i) limited spatial or temporal extent and (ii) interpretational challenges due to the complex observation process underlying most ecological field data. This may jeopardise inferences about distribution and population dynamics unless the main features of the observation process are well understood, so that their biasing effects can be removed.

BIRDMAP

The aim of this project is to develop an analytical framework for combining disparate data sets for large-scale spatiotemporal modelling of distribution and abundance which explicitly addresses all aspects of the observation process. We use data on avian distribution and abundance produced by four large and disparate surveys in Switzerland. With the help of Bayesian hierarchical models, we envision ‘reconstructing’ the spatial dynamics of distribution and abundance for up to 180 Swiss breeding bird species over 25+ years in a landscape demography approach.

Based on the foundation of our new analytical framework, in a follow-up study we plan to tackle important ecological and management problems, including demographic causes of population changes in the face of habitat and climate change, demographic community patterns and further topics on optimal monitoring. Our novel approach of merging disparate data sets in time or in space, and the rigorous accommodation of the observation processes in each data source, could lead the way to a much greater generality in population ecological studies and greatly refined inferences about distribution and abundance in biodiversity monitoring.

 

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Resurrecting population responses to past environmental changes from lake sediments

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Piero Guilizzoni from the Institute of Ecosystem Study during sediment sampling in 2012.

In this project, we investigate life-history responses of a freshwater rotifer, Brachionus calyciflorus, in retrospect. This is possible because brachionid rotifers produce dormant stages, so-called resting eggs, some of which remain viable in lake sediments for decades.

During the last century, Lake Orta – a deep, subalpine lake in northern Italy – was severely affected by industrial pollution. In 1926, a newly established textile factory began to discharge copper- and ammonium-sulphate contaminated sewage into the lake. The following acidification of the lake resulted in a dramatic decrease in rotifer diversity and an accumulation of resting eggs in the sediments. From the late 1950s onward, pre-treatment of the sewage prior to discharge gradually improved the quality of the lake water, and recovery was further accelerated by whole-lake liming in 1989 and 1990. Ten years after these liming efforts, the pH of Lake Orta had returned to pre-pollution levels, and copper was virtually absent from the water column.

In collaboration with the Institute of Ecosystem Study in Verbania, Italy, we collected sediment cores from different basins of Lake Orta. Back in the laboratory in Zürich, we screen these cores for brachionid resting eggs, which we try to hatch. Subsamples of rotifer lineages established from successfully hatched resting eggs are then subjected to a variety of treatments mimicking selected water parameters of historic lake conditions. Using such a ‘resurrection ecology’ approach allows us to investigate the adaptive value of life-history differences among rotifer lineages from different sediment layers, with each layer representing a distinct period in the well-documented pollution history of Lake Orta.

 

The video shows a B. calyciflorus female carrying five male eggs.

 

In collaboration with:

Individual strategies, group dynamics and population regulation in cooperative breeders

meerkatsMany species live in socially and spatially structured populations, and the behavioural, evolutionary, and demographic aspects of sociality have been the focus of much theoretical and empirical research. One major shortcoming of the empirical work, due mainly to practical considerations, has been its focus on already-established social groups (either in captivity or in the wild) and its omission of complexity in between-group processes, such as dispersal and new group formation. Natal dispersal of individuals, immigration into existing groups, and new group formation are latent but crucial aspects of dynamics in socially and spatially-structured populations.  The high fitness costs associated with each stage of dispersal (emigration, transience, and settlement) are likely to induce strong selective pressures on within-group social strategies that directly or indirectly relate to dispersal: e.g., inbreeding avoidance, reproductive suppression, mate finding strategies, helping behaviours, etc. The fitness consequence of these social strategies cannot be accurately assessed, and investigations of behavioural, evolutionary, and demographic processes are therefore incomplete, without a socially and spatially explicit approach that accounts for between-group processes.

In this research, we bring together theoretical models, novel telemetry data on dispersal, and long-term individual-based data on within-group processes to provide a spatially explicit investigation of the life history strategies in a cooperatively breeding mongoose, the Kalahari meerkat. Using this new perspective, we will be able to re-evaluate the fitness consequences of alternative social and behavioural strategies while accounting for dispersal in particular and between-group processes in general at an unprecedented detail level.

 

In collaboration with:

Predicting population responses to environmental change

species2A major goal in biodiversity conservation is to predict responses of biological populations to environmental change. To achieve this goal, we must identify early warning signals of the demographic changes that underlie sudden population declines or explosions. Some studies have achieved phenomenological prediction of sudden changes, but recent advances that link trait-based information with demography hint that a mechanistic understanding is within reach. We are developing a predictive framework by investigating how wildlife populations respond demographically, ecologically and evolutionarily to environmental change, and identifying the demographic and phenotypic statistics that can be used as early warning signals of population change. This project will exploit nine unique mammalian systems to identify early warning signals of population change and test these signals on two experimental systems. The results will hopefully provide much-needed predictive insight into how wildlife populations respond to rapid environmental change.

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