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Congratulations dr Falko Buschke & dr Tom Pinceel

After just three years, Falko Buschke‘s Erasmus Mundus PhD fellowship came to an end. Just months later he succesfully defended his PhD thesis. Initially drawn to Belgium with the prospect of doing a thesis on community dynamics with a lot of empirical work, Falko soon settled into a different niche. Making use of the IUCN database he set out to explain the distribution patterns of terrestrial vertebrates in Africa. For this he used a very diverse set of statistical tools. He reconstructed biogeographical patterns in Africa based on how species present in different locations respond to spatial and environmental gradients. He experimented with novel ways to define regional species pools and investigated the drivers of patterns of alpha and beta diversity. Finally, he also experimented with spreading dye models and built a neutral metacommunity model to explain different biogeographical patterns in this  realm. Overall, it was an exciting journey exploring the interface between community ecology and macro ecology.  Falko, it was great having you here.  We will miss your wit and humour now you have returned to South Africa… and will continue to follow your adventures on  http://solitaryecology.com/

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Just two weeks later, Tom Pinceel joined Falko in the league of doctors. After doing a MSc working on genetic patterns in rock pool fairy shrimp, Tom continued along this path and started to explore the hatching strategies of these enigmatic inhabitants of temporary pools worldwide. Tom showed adaptive variation in hatching strategies of pool invertebrates along a gradient of habitat stability. He also revealed that the ancient diversification of fairy shrimp on the Australian continent coincided with a period of intense aridification. When Australia lost most of its rainforests, desert adapted fauna like fairy shrimps seem to have benefited and responded with a spectacular adaptive radiation. This resulted in a nice little booklet with most of his chapters already published. Tom is now continuing his research into delayed hatching as a survival strategy in extreme environments as a prospective post doc. We can only hope he will be able to continue his work in the near future.

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NEW PAPER: Exploring the link between ecology and biogeography in African vertebrates

In a new paper out in the journal Ecography, Falko Buschke tried to explain the distribution patterns of all terrestrial vertebrates that occur in sub Sahara Africa using environmental variables and spatial dispersal related variables.

He found that when you map Africa based on how much variation is explained by dispersal based processes vs. environmental niche based filtering, you can see the contours of the biogeographic regions. This suggests that community structuring processes differ among regions within biogeographic realms.

He also showed that corrections for range size are necessary to extract ecologically meaningful patterns from variation partitioning results.

Finally, he found that unexplained variation was highest in species with small distributions… which is worrying from a conservation perspective as these are often threatened. While we can quite accurately predict distributions of widespread animals, we don’t know very well why certain rarer species are range restricted.

http://onlinelibrary.wiley.com/doi/10.1111/ecog.00860/abstract

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An African Black Rhino. One of the species in Falko’s database.

NEW PAPER: Simulating the effects of climate change on habitat suitability and connectivity in a pond metacommunity

In a new paper published in Freshwater Biology, PhD student Karen Tuytens builds further on a hydrological model for temporary pools I developed in my PhD. Temporary pools are expected to be strongly impacted by the effects of global environmental change. Being directly dependent on precipitation (and occasionally ground water) for filling, changes in precipitation and/or evaporation will have an impact on the length (hydroperiod) and the frequency of inundations.

http://onlinelibrary.wiley.com/doi/10.1111/fwb.12319/abstract

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The model that was developed is a realistic simulation model which can be parametrized for individual pools and which can predict the water levels on a day to day basis based on nothing but pool morphometry and precipitation and evaporation data. By making use of historic climate it is possible to reconstruct the inundation history of a pool and, hence, reconstruct the long term disturbance regime which is relevant to explain both patterns of diversity as well as adaptive trait variation among populations.

However, the main advantage explored in this paper is the ability to simulate the effects of different IPCC climate change scenarios on inundation patterns. Karen did not only show that inundations are likely to be become shorter resulting in shorter growing seasons for aquatic fauna, she also modeled connections that are formed between pools during heavy rains. Under future scenarios that include less precipitation and higher evaporation, these connections formed less frequently. Overall, this shows that climate change can not only affect habitat suitability but also connectivity in clusters of aquatic habitats. This is relevant since different levels of connectivity can have pronounced effects, not only on the persistence of populations but also on diversity and the functioning of metacommunities.

The code of the model is optimized for the R programming environment and is readily available in the appendix of the paper. At the moment, the model is optimized to work in very simple aquatic habitats such as rock pools which have no groundwater influence and don’t leak water. However, Karen is currently extending the model to make it applicable for more complex temporary aquatic habitats such as temporary wetlands.

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NEW PAPER: Handling cumulative impacts during the environmental decision-making process

In a side-project of his PhD Falko Buschke  published a new paper in Journal of Nature Conservation on how different decision making strategies affect the exploitation of natural habitat. He shows that taking into account cumulative costs (e.g. earlier developments of an area and associated costs in terms of habitat loss) in different ways (not at all/ higher cost for additional developments / equal-division of costs among early and late developers) will have profound effects on how much habitat will be destroyed in the end. But this is just a start…

http://www.sciencedirect.com/science/article/pii/S1617138114000181

Falko explains the story behind the paper and the consequences of his findings in detail on his blog: The Solitary Ecologist

http://solitaryecology.com/2014/04/21/cumulative-impacts/

New paper: The sunglasses effect – egg shell pigmentation modulates hatching in zooplankton

In freshwater zooplankton, that survive unfavorable periods of winter cold or drought as dormant eggs in the sediment, light is an important cue that may activate the embryo to hatch. If no light is detectable then the egg is probably buried and it would be a bad idea to hatch. We investigated the light-activation process of zooplankton resting eggs using a rock-pool fairy shrimp as a model. We showed that light activation entails a relatively simple mechanism involving a light-energy threshold. These results illustrate the potential adaptive value of light activation but also highlighted the possible role of variation in eggshell pigmentation as a risk-spreading strategy. How does this work?

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Much like  a pair of sunglasses, the egg shell modulates how much light is absorbed. Consequently embryos in eggs with a darker egg shell should be less responsive to light. This is exactly what we found. In darker eggs, the embryo responds later, presumably because the light energy threshold is reached later. Given that there is often strong variation in the color of eggs in populations and in clutches of eggs, this simple ‘sunglasses effect’ can ensure that not all eggs will hatch at the same time. As a result the emerging larvae that use different food sources when they get older are less likely to compete with one  another. As such, it could represent a simple, yet potentially effective risk spreading strategy.

While the effectiveness of this strategy within inundations was demonstrated, its potential role in spreading hatching over different inundations remains unknown. Tests are needed to assess whether degradation of pigments over time may be an adaptive mechanism that prevents resting eggs from becoming locked in diapause. Additionally, given the similarities in observed responses to light activation in both crustacean resting eggs and plant seeds, parallel patterns in these taxonomically distant groups might possibly reflect an old evolutionary mechanism tapping the same biochemical pathways, but this hypothesis also remains to be confirmed.

The paper is accessible via this link:

Pinceel et al 2013_light induced dormancy termination

New project in Tanzania

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A joint inter university collaboration was set up between the Flemish universities and the Nelson Mandela institute of Science and Technology in Arusha, Tanzania. The project was officially launched in September 2013. Within the project, which will run for at least six years, I will be supervising a PhD student working on the ecology of wetlands in the Pangani floodplain. The aim is investigate the impact of variation in hydrology and anthropogenic disturbance on wetland functioning and biodiversity, quantify ecosystem services and formulate more effective management strategies.

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Fairy shrimp rediscovered in Belgium

Picture of an adult male fairy shrimp of the species Branchipus schaefferi taken by Aline Waterkeyn

Branchipus schaefferi

Fairy shrimp re-discovered in Belgium

Fairy shrimps (Crustacea, Anostraca) are specialized inhabitants of inland water bodies that periodically dry or freeze over. Tipped of by local conservationists we traveled to Hainaut and were able to confirm the first observation since 1997 of a member of this basal crustacean order in Belgium and the first sighting of the species Branchipus schaefferi Fischer, 1834 since 1930. Nineteen populations were found in a restricted area. The current study illustrates that populations of fairy shrimp can remain undetected, although individuals are relatively large (1 – 4 cm) and conspicuous and often characterized by bright coloration, and even in relatively well-studied and monitored regions, such as Belgium. Large branchiopods are threatened in many parts of the world and notably in Western Europe. The main reason for this is the loss of temporary aquatic habitats as a result of intensive agriculture and urbanisation, and the few remaining habitats are often degraded.

Fairy shrimp wheel track habitat

Fairy shrimp wheel track habitat

While public incentive to conserve a rare group of crustaceans may be limited, it is important to realize that temporary ponds not only house a unique crustacean fauna, but are also of vital importance for other endangered species of plants and animals (Williams, 2006). These include macrophytes, dragonflies and amphibians specifically linked with temporary waters. Substantial efforts and financial support have been directed at protecting certain endangered amphibians that use temporary ponds for breeding, such as the natterjack toad (Bufo calamita) and the fire bellied toad (Bombina bombina). Temporary pond restoration and construction projects performed for these ‘flagship’ species (e.g. EU life project Bombina) are likely to be beneficial for other typical temporary pond organisms too. For instance, different rare macrophytes were shown to re-emerge from old seed banks during pond restoration projects (Hilt et al., 2006). Due to the prolonged viability of their dormant eggs (Brendonck, 1996), it is not unlikely that large branchiopods may emerge from old egg banks present in the sediment. Consequently, a habitat oriented conservation strategy protecting the few remaining high quality temporary ponds and increasing temporary pond densities in the landscape is likely to be most beneficial as a large number of organism groups, including large branchiopods, will benefit from them.

Checking out wheel tracks and farmland ponds in the Binche area in Hainaut

Checking out wheel tracks and farmland ponds in the Binche area in Hainaut

Low predation pressure in combination with plenty of nutrients ensure that fairy shrimp can reach high population densities in temporary pools

Low predation pressure in combination with plenty of nutrients ensure that fairy shrimps can reach high population densities in temporary pools

Read more about the ecology of fairy shrimp and the remaining populations in Belgium in these publications:

Vanschoenwinkel et al. 2013 Natuurfocus 2013-2- Oerkreeftjes duiken opnieuw op in België

Vanschoenwinkel et al 2013 BJZ_kleur

Expedition to the Australian outback 2013

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Sunset at our campsite at Walga Rock

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Where we are going we don’t need roads

During the 2013 expedition we sampled a total of 600 rock pools from 50 inselbergs in Western Australia. The dataset wil be used to get more insight in the drivers of diversity patterns across spatial scales.

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Sampling a rock pool community on Baladgie Rock overlooking a salt lake

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A typical example of a West Australian inselberg in the Cue area in Western Australia

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New paper: human settlement patterns

In a collaboration with the department of archeology at KU Leuven (Ralf Vandam and Eva Kaptijn) we used an ecological perspective and a statistical framework developed in community ecology, to investigate the drivers of human settlement patterns in a valley in Turkey over a time period of 8000 years. Not unsurprisingly typical ecological concepts such as sorting along environmental gradients, spatial autocorrelation and dispersal limitation can also be detected in the structure of early human settlements. It was cool to see that what started out as a fun discussion among friends in a bar (one biologist, one archeologist) now resulted in a proper paper. It was a difficult choice where to submit. Archeology journals have notoriously low impact factors and take a VERY long time to process reviews. On the other hand most ecological journals would not take this type of data. In the end we opted for the open access provided by PlosOne and hope the paper will find an audience. At the time I also conveniently had some remaining bench fee left to spend on publication costs.

In any case, I had a lot of fun playing around with distributions of a species that (often) makes rational decisions and we might try more interdisciplinary stuff in the future.

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The study area: the Burdur plain in central Anatolia with examples of different human artifacts corresponding to different time periods.

 

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Maps of fitted site scores of the first canonical axis of RDA models explaining the abundance of archeological artefacts. Predictor variables are the significant Moran’s eigenvector maps retained after forward selection. A red color indicates high values, blue areas are
indicative of low values. Separate maps are provided for RDA models for each of the six considered time periods. NEO_ECH: Late Neolithic/Early Chalcolithic (6500–5500 BC); LCH_EBI: Late Chalcolithic/Early Bronze Age I (4000–2600 BC); EBII: Early Bronze Age II (2600–2300 BC); A-CH: Archaic-Classical/Hellenistic (750–200 BC). HELL: Hellenistic (333–25 BC); BYZ: Byzantine (610–1300 BC).

Vandam et al. 2013 PloS One

New paper on metacommunity dynamics

DSC_0069In this new paper in this month’s issue of “Ecology” we show how interactions between long term disturbance regime and patch isolation determine diversity patterns in rock pool metacommunities. It’s the final paper that integrates the different processes I studied in the Korannaberg rock pool cluster in South Africa during my PhD. It combines information from dispersal measurements and reconstructions of the hydrological disturbance regime of each of the pools and uses this information to investigate how variation in dispersal influx and disturbance regime affect diversity patterns and patterns of community structure. We found support for the predicted hump shaped relationship between dispersal rates and local species richness, but only in habitats with an intense disturbance regime. Disturbance reduced local diversity, but only when dispersal rates were low (in isolated patches) indicative of a negative synergy. In turn, local richness also decreased in well connected patches, possibly due to a higher abundance of generalist – and disturbance tolerant – predators in these patches.

The paper can be accessed via the journal’s website

http://www.esajournals.org/doi/abs/10.1890/12-1576.1