Skip to content

Posts from the ‘Metacommunity ecology’ Category

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

DSC_9290mod

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

DSC_0404

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.

DSC_9419

Expedition to the Australian outback 2013

DSC_0584

Sunset at our campsite at Walga Rock

DSC_0086

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.

DSC_0756

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

DSC_0548

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

DSC_0629

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.

graph Fig 1 website full

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

 

site scores rda1

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