Mourthe, I. | bioRxiv Science

bioRxiv2026

When suitable habitat is not enough: climate change, habitat loss, and dispersal limitation increase the vulnerability of bald-headed uakaris (Cacajao sp.) in the Amazon Rainforest

AimsSpecies geographic distribution is determined by the interplay between ecological niche and dispersal capacity, which is constrained by biogeographical barriers. Bald-headed uakaris (Cacajao spp.) are highly specialized primates often associated with seasonally flooded forests. In this study, we used ecological niche models to assess the changes in habitat suitability and geographic distribution of uakari species in future scenarios. LocationWestern Amazonia. MethodsWe integrated current deforestation data, species dispersal ability, and ecological niche models to estimate habitat suitability in future scenarios. Our models project shifts in suitable conditions for all species under two Shared Socioeconomic Pathway (SSP) scenarios: intermediate (SSP2-4.5) and very high (SSP5-8.5) greenhouse gas (GHG) emissions. ResultsThree of the five species are projected to experience substantial reductions >62% in suitable habitat conditions within their current ranges by 2050 under both climate scenarios. Our findings indicate that, across the western Amazonia, up to 219,189 km2 and 211,276 km2 of land are projected to be unsuitable within the uakari ranges under the intermediate and very high emissions scenarios, respectively. This is particularly relevant for C. calvus, C. rubicundus, and C. ucayalii, which occupy a region where substantial losses are projected. At the species level, the uakaris may lose between 343 km2 and 84,531 km2 of their ranges in the intermediate scenario and 858 km2 and 76,216 km2 in the very high scenario. In comparison to the losses, the gain of suitable areas is expected to be considerably smaller, varying from 0 to 3,638 km2 in the intermediate scenario, and from 0 to 2,856 km2 in the very high emissions scenario. These gains may occur exclusively across the ranges of C. amuna, C. novaesi, and C. ucayalii. Moreover, the uakaris are estimated to lose between 0.5% and 8% of their current ranges due to deforestation in all scenarios. Shifts in suitability due to climate change varies from 6 to 191 km in the intermediate scenario and from 5 to 168 km in the very high scenario. Main conclusionsOur findings reveal a high sensitivity of the bald-headed uakaris to the impacts of climate change, especially for species with a restricted geographic distribution. It is projected that all species may experience contractions in the suitable areas and spatial suitability within their ranges by the year 2050, underscoring climate change as a relevant threat to these taxa.

ecology↗

bioRxiv2023

A dataset of new occurrence records of primates from the arc of deforestation, Brazil

The arc of deforestation, located between the southern Amazonia and the northern Cerrado of Brazil, is a top deforestation frontier worldwide. The high deforestation rates in this region are caused by human activities and threatens a rich diversity of primates that are still poorly-known and therefore investments into taxonomy and distribution research are urgent to support science-driven conservation of primates of this region. Here we present a dataset of 192 new occurrence records for 22 species of primates of the genera Alouatta, Aotus, Ateles, Cebus, Chiropotes, Lagothrix, Leontocebus, Pithecia, Plecturocebus, Saimiri, and Sapajus, collected during 10 field expeditions carried out across the arc of deforestation between 2015-2018. Based on these occurrence records we extend the ranges of Saimiri collinsi, Sapajus apella, and Alouatta puruensis, identify a potential hybridization zone between A. puruensis and Alouatta discolor, and redefine the range of Plecturocebus moloch. Moreover, this dataset is a useful source of information otherwise scarce for further researches on species distributions and habitat use patterns, on the effect of environmental variables on such patterns, for estimating population sizes, evaluating habitat suitability, for predicting effects of climate change, habitat loss and fragmentation on populations, and for assessing species extinction risks. The ranges of primates endemic to the arc of deforestation, with a few exceptions, are fragile hypotheses, which hampers the establishment of effective conservation efforts for species increasingly threatened on a global deforestation frontier.

zoology↗