Biology subjects

Ribas, C. C.

Publications and source records attributed to Ribas, C. C..

8 recordsLinked to original sources

bioRxiv2026

Habitat specialization structures population divergence and demographic variation in Amazonian floodplain birds

Understanding how species respond to environmental change requires linking ecological traits to gene flow and demographic history across dynamic landscapes. Using population genomic data from twelve co-distributed Amazonian riverine island birds, we show that habitat specialization predicts genetic structure, divergence, and effective population size. Species specialized on dynamic sandbar scrub habitats exhibit higher gene flow, and higher genetic diversity despite smaller effective population sizes. These patterns are consistent with dispersal tracking shifting resources, which decouples genetic diversity from population size. In contrast, river-edge forest specialists show stronger spatial genetic structure and lower genetic diversity despite larger populations, consistent with long-term isolation in more stable habitats. We also detect regional variation in effective population sizes and genetic diversity across Amazonian river sub-basins, potentially reflecting historical differences in floodplain habitat availability. Overall, our results highlight how non-equilibrium dynamics shape genomic variation and emphasize habitat-driven dispersal in diversification and persistence in seasonal systems.

evolutionary biology↗

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

The impact of Quaternary Amazonian river dynamics on patterns and process of diversification in uakari monkeys (genus Cacajao)

AimWestern Amazonia is a region that underwent several landscape changes during the Quaternary. While Riverine Barrier Hypothesis is traditionally used to explain the influence of rivers on speciation, processes such as river rearrangements have been overlooked to explain the geographic distribution and evolutionary history of the Amazonia biota. Here we test how river rearrangements in western Amazonia influenced the evolutionary history of uakari monkeys, a primate group most associated with seasonally flooded forests in western Amazonia. LocationWestern Amazonia TaxonThe uakari monkey (genus Cacajao) MethodsWe performed a continuous phylogeographic analysis using 77 cytochrome b sequences and used digital elevation models to identify the role of landscape and riverscape characteristics in the geographic distribution of Cacajao. Finally, we used genome-wide SNPs variation (ddRADseq) to investigate population structure, gene flow and demographic history in three Cacajao species that were impacted by river rearrangements. ResultsOur continuous phylogeographical reconstruction points that the ancestral Cacajao lineage occupied the flooded forests of the Solimoes River at [~]1.7 Mya, and descendant lineages dispersed throughout western Amazonia more recently. We identified gene flow among both black and bald-headed uakari populations, even across rivers considered barriers (e.g., the Negro River). Landscape analysis showed that river rearrangements influenced the geographic distribution and population structure in Cacajao. The demographic analysis indicates that C. calvus, C. amuna, and C. rubicundus went through a population decline in the last 70 Kya and have a low effective population size. Main conclusionOur results support that the river rearrangements have shaped the geographic distribution and divergence of recently diverged Cacajao lineages. Landscape and riverscape changes, along with retractions of the flooded forests, isolated some Cacajao populations in floodplain areas. Our study also suggests that these events led to the recent population decline in species with a restricted geographic distribution.

evolutionary biology↗

bioRxiv2021

River network rearrangements promote speciation in lowland Amazonian birds

Large Amazonian rivers impede dispersal for many species, but lowland river networks frequently rearrange, thereby altering the location and effectiveness of river-barriers through time. These rearrangements may promote biotic diversification by facilitating episodic allopatry and secondary contact among populations. We sequenced genome-wide markers to evaluate histories of divergence and introgression in six Amazonian avian species-complexes. We first tested the assumption that rivers are barriers for these taxa and found that even relatively small rivers facilitate divergence. We then tested whether species diverged with gene flow and recovered reticulate histories for all species, including one potential case of hybrid speciation. Our results support the hypothesis that river dynamics promote speciation and reveal that many rainforest taxa are micro-endemic, unrecognized and thus threatened with imminent extinction. We propose that Amazonian hyper-diversity originates in part from fine-scale barrier displacement processes -including river dynamics- which allow small populations to differentiate and disperse into secondary contact.

evolutionary biology↗

bioRxiv2021

Population dynamics of Amazonian floodplain forest species support spatial variation on genetic diversity but not range expansions through time

AimWe tested if historical demographic changes of populations occurring on the floodplains of a major Amazon Basin tributary could be associated with range expansions from upper and middle sections of the river, following the establishment of widespread river-created environments during the Late Pleistocene and Holocene. LocationSolimoes River, Western Amazon, South America TaxonMyrmoborus lugubris, Thamnophilus cryptoleucus and Myrmotherula assimilis Methods: We analyzed thousands of UltraConserved Elements to explore spatial patterns of genetic diversity and connectivity between individuals. Range expansions were tested with alternative methods. We quantified habitat preference for the analyzed species in order to test if the occupation of dynamic habitats could predict spatial patterns of genetic diversity. ResultsOur study did not support shared population range expansions related to historical regionalized changes in habitat availability. We found considerable variation in the spatial distribution of the genetic diversity between studied taxa, and that species with higher levels of specialization to dynamic environments have a more heterogeneous distribution of genetic diversity and reduced levels of gene flow across space. Main conclusionsOur results suggest that demographic expansions along the Solimoes River might be linked to geographic homogeneous oscillation in the distribution of floodplain environments, promoting effective population size changes but not range expansion. We found that habitat specificity might be a good predictor of population connectivity along the Amazonian floodplains.

evolutionary biology↗

bioRxiv2020

Landscape configuration of an Amazonian island-like ecosystem drives population structure and genetic diversity of a habitat-specialist bird

ContextAmazonian white-sand ecosystems (campinas) are open vegetation patches which form a natural island-like system in a matrix of tropical rainforest. Due to their clear distinction from the surrounding matrix, the spatial characteristics of campina patches may affect the genetic diversity and composition of their specialized organisms such as the small and endemic passerine Elaenia ruficeps. ObjectivesHere, we estimate the relative contribution of the current extension, configuration and geographical context of campina patches to the patterns of genetic diversity and population structure of E. ruficeps. MethodsWe sampled individuals of E. ruficeps from three landscapes in Central Amazonia with contrasting campina spatial distribution, from landscapes with large and connected patches to landscapes with small and isolated patches. We estimate population structure, genetic diversity, and contemporary and historical migration within and among the three landscapes and used landscape metrics as predictor variables. Furthermore, we estimate genetic isolation by distance and resistance among individuals sampled within landscapes. ResultsWe identified three genetically distinct populations with asymmetrical gene flow among landscapes and a decreasing migration rate with distance. Within each landscape, we found low genetic differentiation without genetic isolation by distance nor by resistance. In contrast, we found differentiation and spatial correlation between landscapes. ConclusionsOur results uncover population dynamics of E. ruficeps through time. Together with previous studies, this suggests that both regional context and landscape structure shape the connectivity among populations of campina specialist birds, and that Amazonian landscapes, together with their associated biota, have responded to recent climatic changes.

ecology↗

bioRxiv2019

Genomic phylogeography of the White Crowned Manakin Pseudopipra pipra (Aves: Pipridae) illuminates a continental-scale radiation out of the Andes

The complex landscape history of the Neotropics has generated opportunities for population isolation and diversification that place this region among the most species-rich in the world. Detailed phylogeographic studies are required to uncover the biogeographic histories of Neotropical taxa, to identify evolutionary correlates of diversity, and to reveal patterns of genetic connectivity, disjunction, and potential differentiation among lineages from different areas of endemism. The White-crowned Manakin (Pseudopipra pipra) is a small suboscine passerine bird that is broadly distributed through the subtropical rainforests of Central America, the lower montane cloud forests of the Andes from Colombia to central Peru, the lowlands of Amazonia and the Guianas, and the Atlantic forest of southeast Brazil. Pseudopipra is currently recognized as a single, polytypic biological species. We studied the effect of the Neotropical landscape on genetic and phenotypic differentiation within this species using genomic data derived from double digest restriction site associated DNA sequencing (ddRAD), and mitochondrial DNA. Most of the genetic breakpoints we identify among populations coincide with physical barriers to gene flow previously associated with avian areas of endemism. The phylogenetic relationships among these populations imply a novel pattern of Andean origination for this group, with subsequent diversification into the Amazonian lowlands. Our analysis of genomic admixture and gene flow reveals a complex history of introgression between some western Amazonian populations. These reticulate processes confound our application of standard concatenated and coalescent phylogenetic methods and raise the question of whether a lineage in the western Napo area of endemism should be considered a hybrid species. Lastly, analysis of variation in vocal and plumage phenotypes in the context of our phylogeny supports the hypothesis that Pseudopipra is a species-complex composed of at least 8, and perhaps up to 17 distinct species which have arisen in the last [~]2.5 Ma.

evolutionary biology↗

bioRxiv2016

Habitat preference predicts genetic diversity and population divergence in Amazonian birds

The ecological traits of organisms may predict important evolutionary parameters such as genetic diversity, population genetic structure, and demographic history. Making these ecological-evolutionary links is difficult because robust, comparable genetic estimates are required from many species with differing ecologies. In Amazonian birds, differences in habitat preference are an important component of ecological diversity. A subset of Amazonian birds is restricted to forest edge and open forest along floodplains, whereas another subset occurs only in the interior of tall, upland forest. Here, we examine the link between habitat and evolutionary metrics using 20 pairs of closely related and co-distributed bird species in which one member of the pair occurs primarily in forest edge and floodplains, and the other occurs in upland forest interior. We use standardized geographic sampling and genomic data from the same set of 2,416 independent markers to estimate genetic diversity, population structure, and demographic history in each species. We find that species of upland forest have higher genetic diversity, greater divergence across the landscape, more genetically distinct populations, and deeper gene histories than floodplain species. Our results reveal that species ecology in the form of habitat preference is an important predictor of genetic diversity and divergence and suggest that floodplain and upland avifaunas in the Amazon may be on separate evolutionary trajectories and require different conservation strategies.

evolutionary biology↗