Bat-Plant Mutualism in Brazil’s Cerrado and Efficiency in Conservation Efforts

Fatin Chowdhury ‘20

bat
Figure 1. Bats reside in the Cerrado neotropical savanna and form critical interactions with various plant species that are present.

A group of researchers based in Europe and Brazil have detailed their literature-based simulation study of mutualistic bat and plant relationships in an area of Brazil called the Cerrado, with an emphasis on efficient conservation. This environment is a neotropical savanna biome characterized by high fauna diversity and distinct habitats, ranging from grasslands to dense gallery forests. These savannas are noted for particular plant groups which are not uniformly found across the Cerrado’s expanse. Additionally, 44% of mammals found in the Cerrado are bat species, which engage in plant-linked seed dispersal and pollination and behaviors such as fructivory and nectivory. The researchers also focused on the threatening effects of anthropogenic factors, such as agricultural and ranching activities, on biodiversity in Cerrado. 

The researchers emphasized network analysis, which examined the relationship between ecological terrain (approached predominantly through plant species) and animal behavior via measurements such as robustness and nestedness of interactions. Scrutinizing networks helps determine the prevalence of competition, extinction, as well as niche distinctions according to species and physical habitat. The researchers used the information gathered to conclude which areas of the Cerrado are most critical in terms of ecological interactions and conservation priority. It was hypothesized that forests would be the setting of most interactions, distinct in interactions from savannah and grassland areas. The researchers also hypothesized that more bat species would be observed to inhabit forests, and that the simulation would indicate forest loss as a precipitating factor related to elevated bat species extinctions. 

Organizing by vegetation type, the researchers quantified bat-plant interactions from the available data using interaction frequency matrices for data organization, analyzing factors such as isolated sub-sets of interactions (designated as compartments), and connectivity within the environment. Modularity in network structure, connected to interaction strength, was explored via a network-focused algorithm, while robustness was characterized as resistance of bat species to co-extinction. The software R was utilized, and cluster dendrograms were constructed to understand interaction networks, with 416 unique interactions, encompassing 28 bat species and 71 plant species being included. 

Despite constituting a mere 5% of the area, gallery forests were the location type exhibiting the greatest number of species interactions, as well as the greatest number of unique interactions, and this finding led the researchers to conclude that interactions in the Cerrado are generally clustered and non-random. Furthermore, simulation models indicated that the removal of forest would be most precipitous in terms of causing the extinction of many bat species, while savanna and grassland removal would be less impactful. Such findings enhance the possibility of targeted, efficient conservation efforts. 

 

References:

  1. Oliveira, et al., Protecting the Cerrado: where should we direct efforts for the conservation of bat‑plant interactions?. Biodiversity and Conservation 28, 2765–2779 (2019). doi: 10.1007/s10531-019-01793-w.
  2. Image retrieved from: https://unsplash.com/photos/MTcfS3HUak8
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