Biology subjects

Revilla, E.

Publications and source records attributed to Revilla, E..

4 recordsLinked to original sources

bioRxiv2024

Trophic adaptation of large terrestrial omnivores to global change

Large omnivores at the top of food webs play a key role in ecosystems, as their ability to feed on multiple trophic levels stabilizes food-web dynamics and impacts ecosystem functioning. However, it is largely unexplored how large omnivores adapt their trophic interactions to altered resource availability under global change, particularly in terrestrial ecosystems. Here, we combine macroecological and paleoecological approaches and reveal that extant bears, the largest terrestrial omnivores, adapt their trophic position in food webs dynamically to net primary productivity and growing season length. Throughout their geographic ranges, extant bears occupy higher trophic positions in unproductive ecosystems with short growing seasons than in productive ecosystems with long growing seasons. Consistent with this geographic pattern, the trophic position of the brown bear sharply decreased at the transition from the Late Pleistocene to the Holocene, coinciding with an increase in net primary productivity and growing season length. These findings demonstrate that trophic interactions of omnivores are not static but change dynamically in response to environmental change. Our findings suggest that global change impacts on primary production and vegetation seasonality may trigger shifts in the functional role of omnivores, with consequences for food webs and ecosystem functions. Significance statementLarge omnivores play a key role in ecosystems, as they stabilize food-web dynamics and impact ecosystem functioning. However, how omnivores adapt their trophic interactions to changes in resource availability under global change remains unexplored. Combining macroecological and paleoecological approaches, we show that extant bears, the largest terrestrial omnivores, occupy lower trophic positions in food webs as net primary productivity and growing season length increase. This trophic adaptation is evident across the geographic ranges of all extant terrestrial bear species and for brown bears at the transition from the Late Pleistocene to the Holocene. Therefore, impacts of global change on primary production and vegetation seasonality may trigger shifts in the functional role of omnivores, with consequences for food webs and ecosystems. One sentence summaryGlobal changes in primary productivity and vegetation seasonality alter the functional role of large omnivores in terrestrial ecosystems.

ecology↗

bioRxiv2022

Road encroachment mediates species occupancy, trait filtering and dissimilarity of songbird communities

Assessing the road effects on biodiversity is challenging because impacts may depend on both wildlife responses to roads and on the spatial arrangement of roads. We questioned whether an increase in road encroachment i.e., the advancement of roads into non-urban areas, leads to significant changes (positive and negative) in species occurrence, and if so, whether those changes are linked to specific traits related to perturbation sensitiveness, therefore acting as filters that increase the community compositional dissimilarity. Using a large citizen-science dataset of point-counts performed throughout Iberian Peninsula (4,459 unique survey sites), we modelled the effect of road density on the occurrence of common songbirds (n=58), while accounting for potential confounding effects of environment and survey effort. We then tested if species occurrence patterns would be linked to specific traits related to the ability to cope with human presence. Finally, we assessed how road density affect the community compositional dissimilarity. We estimated 24 (41%) and 12 (21%) species to be negatively and positively affected by roads, respectively. Increased road encroachment was positively related with a higher prevalence of urban dwellers and negatively related with the occurrence of species nesting and foraging on the ground. Furthermore, increasing road density translated into an increasing community compositional dissimilarity, mostly due to species turnover. Our study support previous research showing that roads have different effects on the occurrence of different species, but we revealed that at least three species' traits have a clear relation with such road responses. Such trait filtering is probably causing a high species turnover between songbird communities occurring in roaded and nearby roadless areas. Overall, we found that different species-specific responses to roads translates into changes at the community level. Landscape and road-network management should be conceived acknowledging that roads are contributing to biodiversity changes. As so, building upon the concepts of Land Sharing / Land Sparing, conservation actions should be tailored according to the different species responses e.g., road verge management targeting species having a positive relation with road density; and compensation actions targeting species showing a negative response toward roads.

ecology↗

bioRxiv2019

Global mammalian zooregions reveal a signal of past human impacts

Ecologists have long documented that the worlds biota is spatially organized in regions with boundaries shaped by processes acting on geological and evolutionary timescales. Although growing evidence suggests that human impact has been key in how biodiversity is currently assembled, its role as a driver of the geographical organization of biodiversity remains unclear. Here, we quantify the relative importance of human land use from [~]5000 years ago to predict the current assemblage of terrestrial mammals in biogeographical regions across the Earth. Results show that past anthropogenic land use has left an imprint on the taxonomic differentiation of some of the largest biogeographical realms, whereas land use at present stands out as a driver of the taxonomic differences between medium-sized subregions, i.e., within and among continents. Our findings highlight the far-reaching effect that past anthropogenic actions have had on the organization of biodiversity globally.

ecology↗

bioRxiv2018

Human activity is altering the world’s zoogeographical regions

Human activity leading to both species introductions and extinctions is widely known to influence diversity patterns on local and regional scales. Yet, it is largely unknown whether the intensity of this activity is enough to affect the configuration of biodiversity at broader levels of spatial organization. Zoogeographical regions, or zooregions, are surfaces of the Earth defined by characteristic pools of species, which reflect ecological, historical, and evolutionary processes acting over millions of years. Consequently, it is widely assumed that zooregions are robust and unlikely to change on a human timescale. Here, however, we show that human-mediated introductions and extinctions can indeed reconfigure the currently recognized zooregions of amphibians, mammals, and birds. In particular, introductions homogenize the African and Eurasian zooregions in mammals; reshape boundaries with the reallocation of Oceania to the New World zooregion in amphibians; and divide bird zooregions by increasing biotic heterogeneity. Furthermore, the combined effect of amphibian introductions and extinctions has the potential to divide two zooregions largely representing the Old and the New World. Interestingly, the robustness of zooregions against changes in species composition may largely explain such zoogeographical changes. Altogether, our results demonstrate that human activities can erode the higher-level organization of biodiversity formed over millions of years. Comparable reconfigurations have previously been detectable in Earths history only after glaciations and mass extinction events, highlighting the profound and far-reaching impact of ongoing human activity and the need to protect the uniqueness of biotic assemblages from the effects of future species introductions and extinctions.

ecology↗