Pleistocene climatic oscillations induced climatic, environmental, and eustatic changes in the Chacoan-Pampean Plain (CPP), profoundly impacting species' distribution, genetic diversity, population dynamics, and lineage diversification. Herein, we investigated how riverine barriers, landscape, and climate influenced the distribution and diversification of frogs of the South American lowlands.
The mid-latitude South American plains, including the Chaco and the Pampa biomes.
Oven frog Leptodactylus latinasus.
We used mitochondrial sequences and genome-wide SNP data throughout the species' distribution to assess population structure, infer phylogenetic relationships, and estimate divergence times. Also, we implemented spatially explicit models, demographic analyses, and tested alternative hypotheses of isolation and migration. We used ecological niche modelling (ENM) to reconstruct changes in geographical distribution and potential ancestral areas.
We detected strong intraspecific phylogeographic structure, with significant breaks coinciding with interglacial periods, while cold phases were associated with bottlenecks and secondary contact events. We observed an intergradation zone between the Paraná River and the Chacoan-Pampean biome limit, supported by significant bidirectional gene flow between nuclear groups.
Our findings highlight the effects of the climatic fluctuations on population dynamics and lineage divergence, the role of the Paraná River as a semipermeable barrier, the Chaco-Pampa ecotone as an environmental barrier, and the influence of sea level changes on lineage isolation and connectivity. The biogeographic pattern and divergence times of L. latinasus are concordant with the diversification of other frogs co-occurring in the CPP.
Freshwater rock pools are ephemeral and fragile habitats that support specialised animal taxa. While distributed worldwide, these habitats are usually neglected and overlooked. We used DNA metabarcoding and metaphylogeographic approaches to study inter and intraspecific tardigrade biodiversity to identify their biogeographic patterns to inform conservation measures.
Europe.
Present.
Tardigrades.
We conducted DNA metabarcoding targeting a fragment of the cytochrome oxidase subunit 1 gene of 163 freshwater rock pools from four sites in Sweden, Poland and Italy to analyse the effect of both short and long distance on their alpha diversity and genetic differentiation.
A total of 85 tardigrades OTUs (species-level clusters) were detected, with the most prevalent taxa across all samples being species from the genus Ramazzottius. OTUs richness was mostly driven by a negative relationship with rock pool depth and site-specific differences. For seven OTUs a phylogeographic analyses revealed a strong founder effect and a variable effect of geographic distance and climate on their population structures.
The high biodiversity and presence of potential specialised taxa highlight the conservation value of freshwater rock pools. While some tardigrade species may be able to easily disperse and have a large geographic range, other species show isolation by distance patterns and their genetic diversity may be negatively affected by habitat loss. Our results call for a bigger effort in identifying, mapping, characterising and protecting freshwater rock pools as underlooked but important habitats.
We aimed to evaluate the genetic diversity and demographic history of an arboreal and forest-dependent species, the black-fronted titi monkey (Callicebus nigrifrons), and tested if the distribution of its genetic variability is influenced by the Grande River, which is the major river inside the area of the distribution of the species.
The sampling localities were spread throughout the entire distribution area of C. nigrifrons in southeastern Brazil.
Black-fronted titi monkey, Callicebus nigrifrons (Primates: Pitheciidae).
We assessed the population genetic structure and performed molecular variance, phylogenetic and demographic history analyses using single nucleotide polymorphisms (SNPs) derived from Genotyping by Sequencing (GBS) and mitochondrial markers (COI and Cyt b).
The spatial distribution of the genetic clusters based on neutral SNPs and mitochondrial haplogroups evidenced the partitioning of populations by the major river within the geographic distribution of C. nigrifrons. SNPs revealed signs of an ancient demographic decrease in both populations from each side of the main channel of the Grande River. On the other hand, the mitochondrial analyses pointed to a slight population expansion dating during the Holocene for both populations, suggesting an increase of suitable areas for the species in this period.
We supported the hypothesis of the influence of rivers on the distribution of genetic diversity of C. nigrifrons. Such inferences shed light on the potential effects of historical barriers and climate changes on the distribution pattern of the genetic variability of the titi monkeys, considering their current geographic occurrence.
Species richness is generally lower in marine than in terrestrial ecosystems, but the reasons behind this disparity remain unclear. This study examines whether marine mammals diversify at a slower pace than their non-marine counterparts, aiming to shed light on the factors explaining potential diversification differences among them.
Global.
Contemporary.
Mammals.
We combined time-calibrated phylogenies, species distribution data, and life-history traits to compare DR variation among marine and non-marine mammals, and to assess DR correlation with ecological realm and species traits.
Contrary to previous findings at higher taxonomic scales, our results show that marine mammals do not exhibit lower DR than non-marine mammals, but even higher depending on the phylogenetic framework. Our regression analyses indicate that taxonomy (particularly family) is the dominant predictor of DR variation among mammals rather than the ecological realm. Still, DR appears negatively correlated with body mass in marine mammals and with range size in non-marine mammals. Besides, the geographic distribution of DR points to a more uniform pattern in marine than in non-marine artiodactyls, for which high DR values concentrate in the Northern Hemisphere. Conversely, high DR values for marine carnivores are clustered around the poles, while a more homogeneous distribution is observed across continents for their terrestrial relatives.
These findings challenge the conventional view that marine ecosystems inherently constrain species diversification. Instead, they suggest that taxonomy and species-specific traits, rather than the ecological realm alone, are the primary drivers of mammalian diversification. Our study emphasizes the complexity of mammalian evolutionary patterns and the importance of integrating taxonomic, ecological, and biogeographic factors in macroevolutionary analyses.
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