Biology subjects

Dallas, T.

Publications and source records attributed to Dallas, T..

3 recordsLinked to original sources

bioRxiv2020

Weak support for the abundant niche-centre hypothesis in North American birds

Species abundance is expected to decrease from the centre towards the edge of their ecological niches (abundant niche-centre hypothesis). Recently, Osorio-Olvera et al. (2020) reported strong support for the abundant niche-centre relationship in North American birds. We demonstrate here that methodological decisions strongly affected perceived support. Avoiding these issues casts doubt on conclusions by Osorio-Olvera et al. and the putative support for the abundant nichecentre hypothesis in North American birds.

ecology↗

bioRxiv2020

Environmental biases in the study of ecological networks at the planetary scale

Ecological networks are increasingly studied at large spatial scales, expanding their focus from a conceptual tool for community ecology into one that also adresses questions in biogeography and macroecology. This effort is supported by increased access to standardized information on ecological networks, in the form of openly accessible databases. Yet, there has been no systematic evaluation of the fitness for purpose of these data to explore synthesis questions at very large spatial scales. In particular, because the sampling of ecological networks is a difficult task, they are likely to not have a good representation of the diversity of Earths bioclimatic conditions, likely to be spatially aggregated, and therefore unlikely to achieve broad representativeness. In this paper, we analyze over 1300 ecological networks in the mangal.io database, and discuss their coverage of biomes, and the geographic areas in which there is a deficit of data on ecological networks. Taken together, our results suggest that while some information about the global structure of ecological networks is available, it remains fragmented over space, with further differences by types of eco-logical interactions. This causes great concerns both for our ability to transfer knowledge from one region to the next, but also to forecast the structural change in networks under climate change.

ecology↗

bioRxiv2019

Summer drought decreases the predictability of local extinctions in a butterfly metapopulation

The ecological impacts of extreme climatic events on population dynamics and/or community composition are profound and predominantly negative. Here, using extensive data of an ecological model system, we test whether predictions from ecological models remain robust when environmental conditions are outside the bounds of observation. First, we report a 10-fold demographic decline of the Glanville fritillary butterfly metapopulation on the [A]land islands (Finland). Next, using climatic and satellite data we show that the summer of 2018 was an anomaly in terms of water balance and vegetation productivity indices across the habitats of the butterfly, and demonstrate that population growth rates are strongly associated with spatio-temporal variation in climatic water balance. Finally, we demonstrate that covariates that have previously been identified to impact the extinction probability of local populations in this system are less informative when populations are exposed to (severe) drought during the summer months. Our results highlight the unpredictable responses of natural populations to extreme climatic events.

ecology↗