Biology subjects

Alencar, L.

Publications and source records attributed to Alencar, L..

3 recordsLinked to original sources

bioRxiv2026

The macroevolutionary impact of an innovation reversal in ray-finned fishes

The evolution of new traits can drive species diversification by facilitating the use of new resources, but environmental change may turn these same adaptations into liabilities.Trait loss is also often associated with the origin of new ecologies, but how losses modulate diversification remains unclear. The swim bladder allows ray-finned fishes to regulate their buoyancy and exploit ecosystems throughout the water column, yet this organ has been lost many times among species-rich lineages. Here, we show that timing and ecological context control the macroevolutionary effects of swim bladder loss. Many lineages of fishes lost the swim bladder over the last 66 million years as they specialized for benthic habitats where buoyancy regulation is unnecessary. Swim bladder loss enabled the descendants of these benthic fishes to diversify in the deep sea where extreme pressure makes its inflation untenable, and in the frigid, oxygen-saturated Southern Ocean, where loss of the oxygen delivery mechanisms required for swim bladder inflation carries little physiological cost. Yet, we detect a selective filter associated with swim bladder loss during extreme global warming 56 to 50 million years ago, when its absence limited the capacity of fishes to escape ecological disruptions on the ocean floor. These contrasting patterns explain how the loss of a complex trait promoted major ecological transitions without increasing overall diversification through deep time. As human activity drives rapid global warming, the evolutionary legacies of swim bladder loss may again shape the fate of marine fish diversity.

evolutionary biology↗

bioRxiv2023

There and back again: when and how the world's richest snake family (Dipsadidae) dispersed and speciated across the Neotropical region

AimThe widespread megadiverse Neotropical snake family Dipsadidae occurs in a large range of diverse habitats. Thus it represents an excellent model to study the diversification of Neotropical biota. Herein, by generating a time-calibrated species-level phylogeny, we investigate the origin and historical biogeography of Dipsadidae and test if its two main Neotropical subfamilies, Xenodontinae and Dipsadinae, have different geographical origins. LocationNeotropical region. TaxonDipsadidae (Serpentes). MethodsWe generated a new Bayesian time-calibrated phylogeny including sequences from six genes for 344 species, including 287 species of Dipsadidae. We subsequently estimated ancestral areas of distribution by comparing models in BioGeoBEARS: DEC (subset sympatry, narrow vicariance), DIVALIKE (narrow and wide vicariance), BAYAREALIKE (no vicariance and widespread sympatry), also testing jump dispersal. ResultsThe best models show that Dipsadidae likely originated approximately 50 million years ago (mya) in Asia. Dispersal was a fundamental process in its historical biogeography. The DEC model with jump dispersal indicated that this family underwent a range extension from Asia and posterior vicariance of North and Central America ancestors. Both Xenodontinae and Dipsadinae originated in Central America and dispersed to South America during Middle Eocene, but did so to different regions (cis and trans-Andean South America, respectively). Xenodontinae entered cis-Andean South America around 39 mya and jump dispersed to the West Indies around 33 mya, while Dipsadinae entered trans-Andean South America multiple times 20 - 38 mya. Main conclusionsOur results show that Dipsadidae has an Asian origin and that the two main Neotropical subfamilies originated in Central America, later dispersing to South America in different time periods. The current biogeographical patterns of the family Dipsadidae, the most species-rich snake family in the world, have likely been shaped by complex evolutionary and geological processes such as Eocene land bridges, Andean uplift and the formation of the Panama isthmus.

ecology↗

bioRxiv2022

Geographical and ecological drivers of coexistence dynamics in squamate reptiles

AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSAimC_ST_ABSSpecies richness varies widely across space. To understand the processes behind these striking patterns, we must know what are the relevant drivers underlying species coexistence. Several factors can potentially shape species coexistence such as the speciation process, the time since divergence between lineages, environmental effects, and intrinsic properties of the organisms. For the first time, we model the coexistence dynamics of lizards and snakes across broad temporal and spatial scales, investigating the role of species interactions, dispersal ability, and geographic area. LocationGlobal Time periodLast 20 million years Major taxa studiedSquamata (lizards and snakes) MethodsWe used 448 closely related species pairs and their age since divergence across 100 dated phylogenies. We categorized each pair as sympatric or allopatric and as occurring on islands or continents. We measured morphological traits to quantify niche divergence and used range and body size as proxies for dispersal ability. We applied a model-comparison framework in lizards and snakes separately to evaluate which factors best explained their coexistence dynamics. ResultsWe found that distinct factors drive the coexistence dynamics in lizards and snakes. In snakes, species pairs that coexist tend to occur on islands and are more different in body size, suggesting that both geographical setting and species interactions might be relevant factors. In contrast, we only found evidence that dispersal ability shaped the coexistence of lizards, where species coexist when they have higher dispersal abilities. Main conclusionsLizards and snakes greatly differ in coexistence dynamics. Higher heterogeneity in coexistence dynamics within lizards and group-specific life-history aspects might help to explain these findings. Our results emphasize that the interaction between where organisms are and who they are, ultimately shapes biodiversity patterns. We also highlight interesting avenues for further studies on species coexistence in deep time.

evolutionary biology↗