Abstract: "Researchers have produced the first ever data-based distribution map of Asian elephants for Sri Lanka. This is also the first evidence-based distribution map of Asian elephants for any of the 13 range countries, the researchers say. The study found that elephants currently occur in 60 percent of Sri Lanka, a figure that’s higher than previous estimates based on expert opinions, and also higher than that for any other range state. The majority of the elephants occur outside protected areas, sharing space with humans, the study found. So trying to confine the animals to the limits of protected areas is not a sound conservation strategy, the researchers say. Instead, they recommend a “human–elephant coexistence model,” one that aims to reduce conflict by protecting villages and cultivations with barriers."
25 May 2019
Abstract: "Habitat loss (HL) affects species and their interactions, ultimately altering community dynamics. Yet, a challenge for community ecology is to understand how communities with multiple interaction types—hybrid communities—respond to HL prior to species extinctions. To this end, we develop a model to investigate the response of hybrid terrestrial communities to two types of HL: random and contiguous. Our model reveals changes in stability—temporal variability in population abundances—that are dependent on the spatial configuration of HL. Our findings highlight that habitat area determines the variability of populations via changes in the distribution of species interaction strengths. The divergent responses of communities to random and contiguous HL result from different constraints imposed on individuals’ mobility, impacting diversity and network structure in the random case, and destabilising communities by increasing interaction strength in the contiguous case. Analysis of intermediate HL suggests a gradual transition between the two extreme cases."
Abstract: "It is generally assumed that deforestation affects a species consistently across space, however populations near their geographic range edge may exist at their niche limits and therefore be more sensitive to disturbance. We found that both within and across Atlantic Forest bird species, populations are more sensitive to deforestation when near their range edge. In fact, the negative effects of deforestation on bird occurrences switched to positive in the range core (>829 km), in line with Ellenberg’s rule. We show that the proportion of populations at their range core and edge varies across Brazil, suggesting deforestation effects on communities, and hence the most appropriate conservation action, also vary geographically."
Abstract: "Predator–prey interactions in natural ecosystems generate complex food webs that have a simple universal body-size architecture where predators are systematically larger than their prey. Food-web theory shows that the highest predator–prey body-mass ratios found in natural food webs may be especially important because they create weak interactions with slow dynamics that stabilize communities against perturbations and maintain ecosystem functioning. Identifying these vital interactions in real communities typically requires arduous identification of interactions in complex food webs. Here, we overcome this obstacle by developing predator-trait models to predict average body-mass ratios based on a database comprising 290 food webs from freshwater, marine and terrestrial ecosystems across all continents. We analysed how species traits constrain body-size architecture by changing the slope of the predator–prey body-mass scaling. Across ecosystems, we found high body-mass ratios for predator groups with specific trait combinations including (1) small vertebrates and (2) large swimming or flying predators. Including the metabolic and movement types of predators increased the accuracy of predicting which species are engaged in high body-mass ratio interactions. We demonstrate that species traits explain striking patterns in the body-size architecture of natural food webs that underpin the stability and functioning of ecosystems, paving the way for community-level management of the most complex natural ecosystems."
Abstract: "Species, and their ecological strategies, are disappearing. Here we use species traits to quantify the current and projected future ecological strategy diversity for 15,484 land mammals and birds. We reveal an ecological strategy surface, structured by life-history (fast–slow) and body mass (small–large) as one major axis, and diet (invertivore–herbivore) and habitat breadth (generalist–specialist) as the other. We also find that of all possible trait combinations, only 9% are currently realized. Based on species’ extinction probabilities, we predict this limited set of viable strategies will shrink further over the next 100 years, shifting the mammal and bird species pool towards small, fast-lived, highly fecund, insect-eating, generalists. In fact, our results show that this projected decline in ecological strategy diversity is much greater than if species were simply lost at random. Thus, halting the disproportionate loss of ecological strategies associated with highly threatened animals represents a key challenge for conservation."
15 May 2019
Abstract: "A new review paper finds that the loss of Africa’s forest elephants has broad impacts on their ecosystems, including hitting several tall tree species, which play a key role in sequestering carbon dioxide. Forest elephants disperse large seeds, keep the forest canopy open, and spread rare nutrients across the forest, benefiting numerous species across the African tropics. While the IUCN currently defines African elephants as a single species, scientists believe it long past time to split them into two distinct species, savanna and forest, to bolster protection for both from the ivory trade."
14 May 2019
Abstract: "The U.N.’s Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services released a summary of far-reaching research on the threats to biodiversity on May 6. The findings are dire, indicating that around 1 million species of plants and animals face extinction. The full 1,500-page report, to be released later this year, raises concerns about the impacts of collapsing biodiversity on human well-being."