community ecology | Ecology for the Masses

Making Food Webs Out Of (Almost) Nothing At All

Posted on April 6, 2022 by Tanya Strydom Leave a comment

Food web reconstruction through phylogenetic transfer of low-rank network representation (2022) Strydom and Bouskila et al., Methods in Ecology and Evolution, https://doi.org/10.1111/2041-210X.13835

The Crux

Understanding food webs (and more generally how different species interact) is important in helping us to understand ecological processes, but sampling (observing) interactions in the field is pretty challenging. Observing a parrot? Simple. Observing a possum? No problem. Observing a parrot evicting a possum from a tree-hollow? Rarer.

This means that data on species interactions is sparse. But we do have data for some regions, and things like computers and fancy maths (think machine learning) at our disposal. Which leads to the question: can we learn something from the places for which we do have interaction data and ‘transplant’ this knowledge and create an interaction network for a region with no data at all?

The focus here is to try and use predictive methods to help and at least give us a idea of who might potentially be eating who and use this to construct a metaweb (a full list of potential interactions) for a region that has plenty of species data, but no species interaction data.

Paper of the Week

Can A Harsh Climate Create Stronger Interactions Between Species?

Posted on January 27, 2021 by Sam Perrin Leave a comment

Bowler et al. (2020) Impacts of predator-mediated interactions along a climatic gradient on the population dynamics of an alpine bird. Proceedings of the Royal Society B, 287, https://doi.org/10.1098/rspb.2020.2653.

The Crux

Whether or not a species will survive in an area can usually be broken down into two broad categories: how suitable the environmental characteristics of that area are (temperature, elevation, rainfall), and how it interacts with the other species found nearby. Early ecological theory predicted that in harsh environments, how a species interacts with other species wouldn’t matter as much, and would only come into play when the area was easier for the species to inhabit.

Yet more modern work often contradicts this theory. For instance, the Alternative Prey Hypothesis (APH) suggests that in areas where there are relatively few species as a result of harsh climates, interactions between those few species will be relatively strong. For example, if a prey species declines one year, then its usual predator must find an alternative prey species. This creates an indirect interaction between the two prey species, which is particularly strong in harsh environments where there aren’t other species around.