Biology subjects

Rabelo, R. M.

Publications and source records attributed to Rabelo, R. M..

3 recordsLinked to original sources

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↗

bioRxiv2019

Butterfly assemblages from Amazonian flooded forests are not more species-poor than from unflooded forests

The Amazonian flooded and upland forests harbour distinct assemblages of most taxonomic groups. These differences can be mainly attributed to flooding, which may affect directly or indirectly the persistence of species. Here, we compare the density, richness and composition of butterfly assemblages in vaorzea and terra firme forests, and evaluate whether terrain elevation and flooding can be used to predict the assemblage structure. We found that the total abundance and number of species per plot is higher in vaorzea than in terra firme forests. Vaorzea assemblages showed a higher dominance of abundant species than terra firme assemblages, in which low-flying Haeterini butterflies had higher abundance. After standardizing species richness by sample size and/or coverage, species richness estimates for vaorzea and terra firme forests were similar. There was strong turnover in species composition across vaorzea and terra firme forests associated with terrain elevation, most likely due to differences in the duration of flooding. Despite a smaller total area, less defined vegetation strata, more frequent disturbances and the younger geological age of floodplain forests, Nymphalid butterfly assemblages are not more species poor there than in unflooded forests.

ecology↗

bioRxiv2019

Prey abundance drives habitat occupancy by jaguars in Amazonian floodplain fluvial islands

The jaguar (Panthera onca) is widely distributed across a broad range of habitat types, where its feeding habits and habitat use patterns vary significantly. The jaguar and its main arboreal prey - the brown-throated sloth (Bradypus variegatus) and the red howler monkey (Alouatta juara) - are widespread in the Amazonian floodplain forests of the Mamiraua Reserve. These forest-dwelling species are the most common mammal species both in the continuous forest and the forest patches surrounded by a river matrix - the fluvial islands - of the Solimoes and Japura rivers. We used sign surveys along line-transects to assess the pattern of habitat occupancy by jaguars in Amazonian floodplain forests. Specifically, we (i) tested whether habitat occupancy by jaguars differs between river islands and continuous forest; and (ii) evaluated whether and how the local abundance of sloths and howler monkeys influence the probability of site occupancy by jaguars. We built an occupancy model and used Bayesian inference to reach these goals. The proportion of sites estimated to be used by jaguars was{psi} = 0.75 (HPD95: 0.36-1.00), and it did not differ between islands and continuous forest. The abundance of both prey species had a direct influence on jaguars habitat use, whereas the aquatic matrix seems to have a negligible effect on the use of islands by jaguars. We conclude that the isolation of the river islands within the aquatic matrix does not hamper jaguars to use them. We also conclude that prey search modulates jaguars habitat occupancy patterns with both prey species having a similar effect. This finding is compatible with the previously reported importance of sloths to the diet of jaguars in the study region despite its lower abundance than howlers. Finally, we suggest that sign surveys are an alternative method to assess the pattern of jaguar habitat occupancy in floodplain forests.

ecology↗