Biology subjects

Rodrigues, A. S. L.

Publications and source records attributed to Rodrigues, A. S. L..

5 recordsLinked to original sources

bioRxiv2021

Combined effects of bird extinctions and introductions in oceanic islands: decreased functional diversity despite increased species richness

AimWe analyse the functional consequences of the changes in species composition resulting from extinctions and introductions on oceanic island bird assemblages. Specifically, we ask if introduced species have compensated the functional loss resulting from species extinctions. LocationSeventy-four oceanic islands (>100 km2) in the Atlantic, Pacific and Indian Oceans. Time periodLate Holocene. Major taxa studiedTerrestrial and freshwater bird species. MethodsWe compiled a species list per island (extinct and extant, native and introduced), and then compiled traits per species. We used single-trait analyses to assess the effects of past species extinctions and introductions on functional composition. Then, we used probabilistic hypervolumes in trait space to calculate functional richness and evenness of original versus present avifaunas of each island (and net change), and to estimate functional originality of extinct and introduced species. ResultsThe net effects of extinctions and introductions were: an increase in average species richness per island (alpha diversity), yet a decline in diversity across all islands (gamma diversity); an average increase in the prevalence of most functional traits (23 out of 35) yet an average decline functional richness and evenness, associated with the fact that extinct species were functionally more original (when compared to extant natives) than introduced species. Main conclusionsIntroduced species are on average offsetting (and even surpassing) the losses of extinct species per island in terms of species richness, and they are increasing the prevalence of most functional traits. However, they are not compensating the loss of functional richness due to extinctions. Current island bird assemblages are becoming functionally poorer, having lost original species and being composed of functionally more homogeneous species. This is likely to have cascading repercussions on the functioning of island ecosystems.

ecology↗

bioRxiv2021

Mismatch between bird species sensitivity and the protection of intact habitats across the Americas

Protected areas, the most prevalent international policy mechanism for biodiversity conservation, are highly heterogeneous in their effectiveness at buffering ecosystems and species habitats from human pressure. Protected areas with intense human pressure cannot protect species that are highly sensitive to human activities. Here, we use 60 million bird observations from the eBird citizen science platform to estimate the sensitivity to human pressure of each bird species breeding in the Americas (Nearctic and Neotropical regions). We find that high-sensitivity species, while found in all ecoregions, are concentrated in the tropical biomes. Ecoregions with large proportions of high-sensitivity species do not have more intact protected habitat, resulting in a low coverage of intact protected habitat for many high-sensitivity species. What is more, 139 high-sensitivity species have little or no intact protected habitat within their distributions while being threatened with extinction. Finally, we show that protected area intactness is decreasing faster in ecoregions with many high-sensitivity species. Our results highlight a major mismatch between species conservation needs and the coverage of intact protected habitats, and will likely hamper the long-term effectiveness of protected areas at retaining species. We highlight ecoregions where the protection and management of intact habitats, complemented by the restoration of degraded ones, is urgently needed to avoid extinctions.

ecology↗

bioRxiv2020

How many bird and mammal extinctions has recent conservation action prevented?

Aichi Target 12 of the Convention on Biological Diversity (CBD) aims to prevent extinctions of known threatened species. To measure its success, we used a Delphi expert elicitation method to estimate the number of bird and mammal species whose extinctions were prevented by conservation action in 1993 - 2020 (the lifetime of the CBD) and 2010 - 2020 (the timing of Aichi Target 12). We found that conservation prevented 21-32 bird and 7-16 mammal extinctions since 1993, and 9-18 bird and 2-7 mammal extinctions since 2010. Many remain highly threatened, and may still become extinct in the near future. Nonetheless, given that ten bird and five mammal species did go extinct (or are strongly suspected to) since 1993, extinction rates would have been 2.9-4.2 times greater without conservation action. While policy commitments have fostered significant conservation achievements, future biodiversity action needs to be scaled up to avert additional extinctions.

ecology↗

bioRxiv2020

Effectiveness of protected areas in conserving tropical forest birds

Protected areas are the cornerstones of global biodiversity conservation efforts1,2, but to fulfil this role they must be effective at conserving the ecosystems and species that occur within their boundaries. This is particularly imperative in tropical forest hotspots, regions that concentrate a major fraction of the worlds biodiversity while also being under intense human pressure3-5. But these areas strongly lack adequate monitoring datasets enabling to contrast biodiversity in protected areas with comparable unprotected sites6,7. Here we take advantage of the worlds largest citizen science biodiversity dataset - eBird8 - to quantify the extent to which protected areas in eight tropical forest biodiversity hotspots are effective at retaining bird diversity, and to understand the underlying mechanisms. We found generally positive effects of protection on the diversity of bird species that are forest-dependent, endemic to the hotspots, or threatened or Near Threatened, but not on overall bird species richness. Furthermore, we show that in most of the hotspots examined this is driven by protected areas preventing both forest loss and degradation. Our results support calls for increasing the extent and strengthening the management efforts within protected areas to reduce global biodiversity loss9-11.

ecology↗

bioRxiv2018

Using a large-scale biodiversity monitoring dataset to test the effectiveness of protected areas in conserving North-American breeding birds

Protected areas currently cover about 15% of the global land area and constitute one of the main tools in biodiversity conservation. Quantifying their effectiveness at protecting species from decline and local extinction involves comparing protected with counterfactual unprotected sites representing \"what would have happened to protected sites if they had not been protected\". Most studies are based on pairwise comparisons, using as counterfactuals neighbour sites to protected areas, but this choice is often subjective and may be prone to biases. An alternative is to use large-scale biodiversity monitoring datasets, which whereby the effect of protected areas is analysed statistically by controlling for landscape differences between protected and unprotected sites, allowing a more targeted and clearly defined measure of protected areas effect. Here we use the North American Breeding Bird Survey dataset as a case study to investigate protected areas effectiveness in conserving bird assemblages. We analysed the effect of protected areas on species richness, assemblage-level abundance and abundance of individual species by modelling how these metrics relate to the proportion of each site that is protected, while controlling for site habitat, altitude, productivity and spatial autocorrelation. At the assemblage level, we found no relationship between protection and species richness or overall abundance. At the species level, we found that species that avoid human activities tend to be favoured by protected areas are the one avoiding human activities. Moreover, we found that forest protected areas presented higher abundances of forest species, making the assemblage more typical of this habitat. We did not find that declining species were particularly favoured by protected areas. Our results highlight the complexity of answering the question of protected areas effectiveness, and the necessity to define clearly metrics measured and the controls used.

ecology↗