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11 recordsLinked to original sources
PubMed2024

Extreme elevational migration spurred cryptic speciation in giant hummingbirds.

The ecoevolutionary drivers of species niche expansion or contraction are critical for biodiversity but challenging to infer. Niche expansion may be promoted by local adaptation or constrained by physiological performance trade-offs. For birds, evolutionary shifts in migratory behavior permit the broadening of the climatic niche by expansion into varied, seasonal environments. Broader niches can be short-lived if diversifying selection and geography promote speciation and niche subdivision across climatic gradients. To illuminate niche breadth dynamics, we can ask how "outlier" species defy constraints. Of the 363 hummingbird species, the giant hummingbird (Patagona gigas) has the broadest climatic niche by a large margin. To test the roles of migratory behavior, performance trade-offs, and genetic structure in maintaining its exceptional niche breadth, we studied its movements, respiratory traits, and population genomics. Satellite and light-level geolocator tracks revealed an >8,300-km loop migration over the Central Andean Plateau. This migration included a 3-wk, ~4,100-m ascent punctuated by upward bursts and pauses, resembling the acclimatization routines of human mountain climbers, and accompanied by surging blood-hemoglobin concentrations. Extreme migration was accompanied by deep genomic divergence from high-elevation resident populations, with decisive postzygotic barriers to gene flow. The two forms occur side-by-side but differ almost imperceptibly in size, plumage, and respiratory traits. The high-elevation resident taxon is the world's largest hummingbird, a previously undiscovered species that we describe and name here. The giant hummingbirds demonstrate evolutionary limits on niche breadth: when the ancestral niche expanded due to evolution (or loss) of an extreme migratory behavior, speciation followed.

Animals↗
PubMed2024

Oceanic islands act as drivers for the genetic diversity of marine species: Cardita calyculata (Linnaeus, 1758) in the NE Atlantic as a case-study.

Geographic distribution, as well as evolutionary and biogeographic processes and patterns of marine invertebrate benthic species are strongly shaped by dispersal ability during the life cycle. Remote oceanic islands lie at the brink of complex biotic and abiotic interactions which have significantly influenced the biodiversity patterns we see today. The interaction between geological environmental change and taxon-specific dispersal modes can influence species evolutionary patterns, eventually delimiting species-specific biogeographic regions. In this study, we compare the population genetic patterns of the marine bivalve Cardita calyculata in the northeast Atlantic, discussing the role of Macaronesian islands during past climatic cycles. The genetic structure and diversity patterns were outlined based on SSR-GBAS loci of 165 individuals and on the mitochondrial COI marker of 22 individuals from the Canary Islands, Madeira, Azores and the Mediterranean. The highly structured genetic pattern found among regions and within archipelagos suggests the central role of oceanic islands in promoting the divergence of the species in both the NE Atlantic and the Mediterranean. The high degree of divergence in the COI dataset (> 7%) suggests the existence of potential cryptic speciation that needs to be further explored with a more comprehensive sampling. Such patterns are only congruent with a scenario where C. calyculata populations were maintained during glacial/interglacial cycles, supporting the role of the studied archipelagos as drivers of diversity for marine biota. We stress the importance of developing studies for species with various life history and dispersal modes. In such a way, a more profound understanding of the biogeographic and evolutionary significance of oceanic islands can catalyse directed conservation efforts, especially in the context of the ongoing climate crisis.

Animals↗
PubMed2026

Molecular identification and diversity assessment of Tyrrhenian Romulea species (Iridaceae).

Taxonomic assignments based only on morphology are often insufficient for delimiting species, particularly in complexes shaped by hybridization and polyploidy, where species boundaries are unclear. This limitation hinders progress in ecological, biogeographic and conservation research. The genus Romulea, distributed across Africa and the Mediterranean Basin, exemplifies this challenge. Despite its remarkable diversity, Mediterranean Romulea has not received much attention from genetic and molecular studies. Here, we present the first multilocus genotype analysis of Mediterranean Romulea taxa, focusing on the Tyrrhenian biogeographic province. Using target-capture sequencing with the universal Angiosperms353 kit, we generated genomic data for 272 individuals representing 18 putative taxa. Our findings reveal genetic groups that align with current taxonomy, the existence of cryptic divergence, and highlight the role of hybridization. Furthermore, analysis of intra-individual genetic diversity suggests one or several allopolyploid origins for Mediterranean Romulea. Four taxa (R. assumptionis, R. revelieri, R. ligustica, R. rollii) are consistently well differentiated across nuclear and plastid datasets, supporting their recognition as distinct species. In contrast, the widespread species R. ramiflora and R. columnae contain well-differentiated groups that may represent cryptic speciation. Several other taxa, including R. x melitensis, R. corsica, and R. bulbocodium, exhibit genomic signatures consistent with hybrid origins. Plastid and nuclear variation patterns are consistent with a hypothesis of rapid radiation in the Tyrrhenian region. These results provide a primary genomic framework for the integrative taxonomy of Romulea.

Genetic Variation↗
PubMed2025

The effects of cryptic diversity on diversification dynamics analyses in Crocodylia.

Incomplete taxon sampling due to underestimation of present-day biodiversity biases diversification analysis by favouring slowdowns in speciation rates towards the recent time. For instance, in diversification dynamics studies in Crocodylia, long-term low net-diversification rates and slowdowns in speciation rates have been suggested to characterize crocodylian evolution. However, crocodylian cryptic diversity has never been considered. Here, we explore the effects of incorporating cryptic diversity into a diversification dynamics analysis of extant crocodylians. We inferred a time-calibrated cryptic-species-level phylogeny using cytochrome b sequences of 45 lineages compared with the formally recognized 26 crocodylian species. Diversification rate estimates using the cryptic-species-level phylogeny show increasing speciation and net-diversification rates towards the present time, which contrasts with previous findings. Cryptic diversity should be considered in future macroevolutionary analyses; however, the representation of cryptic extinct taxa represents a major challenge. Additionally, further investigation of crocodylian diversification dynamics under different underlying genomic data is encouraged upon advances in population genetics. Our case study adds to the diversification dynamics knowledge of extant taxa and demonstrates that cryptic species and robust taxonomic assessment are essential to study recent biodiversity dynamics with broad implications for evolutionary biology and ecology.

Animals↗
PubMed1975

A critical study of the taxonomic value of some tests of assimilation used for the classification of the sporogenous yeasts.

Six texts of assimilation used in the taxonomy of yeasts, (lactose, maltose, cellobiose, trehalose, melibiose, sucrose) have been critically tested by the examination of intracellular enzymic systems. The results obtained among the sporogenous species of Saccharomyces, Kluyveromyces, Pichia, Hansenula, Debaryomyces indicate that cellobiose, lactose, maltose and trehalose tests no longer supply an important value for the speciation, because the number of cryptical osidases is so high.

Classification↗
PubMed2026

Untangling the Arisaema enigma: Investigating the complex evolutionary history and species relationships in North American Arisaema.

PREMISE: The evolutionary history of morphologically variable plant groups is often obscured by cryptic diversity, morphological convergence, and limited genetic data. Arisaema, a diverse genus within Araceae, exemplifies these challenges. Although some taxonomic treatments recognize only two species of North American Arisaema (A. dracontium and A. triphyllum), other studies have identified morphologically distinct groups within both taxa. Here, we reconstructed evolutionary relationships in North American Arisaema, assessed genetic structure and admixture, and tested the monophyly of proposed species. METHODS: We used 2b-RAD sequencing to generate genome-wide SNP data for 146 samples from 31 populations across the eastern United States. Phylogenetic relationships were inferred using maximum-likelihood and Bayesian approaches. Population structure and admixture were assessed using the program structure and principal component analysis (PCA). RESULTS: Both the Arisaema triphyllum and A. dracontium complexes formed well-supported monophyletic groups. Within the A. dracontium complex, we recovered three monophyletic lineages: A. dracontium, A. calciphilum, and A. macrospathum. In the A. triphyllum complex, A. quinatum, A. stewardsonii, and A. allegheniense consistently formed distinct groups. Relationships between A. pusillum and A. acuminatum, and among A. triphyllum s.s., A. purpurascens, and A. striatum were less clearly resolved, likely due to recent or incomplete divergence, gene flow, or polyploidy. CONCLUSIONS: The results support the monophyly of multiple newly proposed taxa within North American Arisaema, but additional sampling across the species' ranges is needed to fully resolve species boundaries. Our study provides the first evolutionary framework for this group, providing a foundation for future ecological, taxonomic, and conservation research in the genus.

Araceae↗
PubMed2026

Genome-wide insights into the evolutionary and demographic history of the red alga Mazzaella laminarioides: Evidence for speciation with ancient migration along the southeast Pacific coast.

The mechanisms driving lineage divergence in red algae remain unexplored, despite the group's remarkable diversity and ancient evolutionary history. The red alga Mazzaella laminarioides, a Chilean intertidal species complex composed of three parapatric cryptic lineages (North, Center, South), offers a valuable system to evaluate these processes, as its life history combines severe dispersal limitation with a haploid-diploid cycle that may influence the emergence of reproductive barriers. We reconstructed its evolutionary history using whole-genome sequencing and nuclear genome assembly of representative individuals from each lineage. Phylogenomic analyses based on 1,507 single-copy orthologs recovered three deeply divergent lineages with limited nuclear discordance consistent with incomplete lineage sorting. For both splits, demographic modelling was most consistent with an Ancient Migration scenario, although support over strict isolation was moderate, suggesting that divergence may have begun with low asymmetric ancestral gene flow followed by subsequent loss of connectivity, demographic bottlenecks, and later population expansion. Coding sequence analyses revealed lineage-specific dN/dS heterogeneity; only one South-lineage locus passed FDR correction (metaxin-1, mitochondrial protein import), with two further South-lineage candidates in chlorophyll and heme biosynthesis falling below the FDR threshold. Together, these signals suggest that divergent selective pressures on energy acquisition may have contributed to divergence at the southern end of the distribution. These results add to the small but growing body of whole-genome data for red algae and, alongside recent macroalgal studies, suggest that ancestral connectivity could be a recurrent feature of lineage divergence even in marine organisms with extremely restricted dispersal.

Rhodophyta↗
PubMed1992

Detection by allozyme electrophoresis of cryptic species of Hypodontus macropi (Nematoda: Strongyloidea) from macropodid marsupials.

Allozyme electrophoresis of 98 Hypodontus macropi from eight different species of hosts using 24 enzymes revealed a complex of at least six sibling species, with 15-50% fixed genetic differences between taxa. Except for the taxon parasitizing Macropus rufus/M. robustus, pairs of parasite taxa were, in each case, sympatric at each locality examined, thus supporting the conclusion that they represent valid species. The existence of a series of host-specific nematode taxa explains many of the inconsistencies noted previously in the host distribution of H. macropi. Comparison of parasite allozyme phenograms with host phylogeny suggests that four of the speciation events could be attributable to cospeciation and two to host switching. A clear case of host switching between M. rufus/M. robustus and M. fuliginosus was found.

Alleles↗
PubMed2025

Integrated genomics and morphological approach reveals interspecific gene flow cases and decodes the origin of selected feathergrasses (Poaceae, Stipa).

Central Asia is a diversity hotspot of arid-adapted grasses from the genus Stipa, with approximately 100 taxa found in the region. Recent studies in the steppe areas of Kazakhstan revealed specimens displaying intermediate morphology, distinguishing them from other taxa that grow sympatrically. Using integrative taxonomy, we investigated whether these individuals resulted from natural speciation or hybridisation, and if so, we would like to know which species were involved in this process feathergrasses. Research conducted in steppes of central Kazakhstan (Kyzylorda region), revealed the existence of individuals morphologically intermediate between S. arabica and S. richteriana, suggesting that these are probably of hybrid origin. Morphology and SNP markers validated the specimens as F1 hybrid between the aforementioned species by cladding separately based on neighbor-joining phylogenetic tree. Moreover, genetic structure displayed a separate cluster and showed almost equal genetic admixture between S. arabica and S. richteriana. Additionally, fastStructure analysis detected two geographically separated cryptic genotypes within S. richteriana population and their involvement in the hybridisation resulted in occurrence of S. × heptapotamica, S. × czerepanovii and S. × korshinskyi which recently were suggested as hybrids. Based on these evidences, we described a new nothospecies S. × kyzylordensis, as F1 hybrid. Furthermore, morphologically, the nothospecies delimited with other hybrids in Kazakh steppe area, marking the first report of hybridisation between S. arabica and S. richteriana, along with molecular evidence for the origin of further species supposed to be hybrids. This finding is crucial to understanding species diversity and hybridisation process in morphologically and genetically distant Stipa species.

Poaceae↗
PubMed2025

Integrating hotspot dynamics and centers of diversity: a review of Indo-Australian Archipelago biogeographic evolution and conservation.

The Indo-Australian Archipelago (IAA) is the world's preeminent marine biodiversity hotspot, distinguished by its exceptional species richness in tropical shallow waters. This biodiversity has spurred extensive research into its evolutionary and biogeographic origins. Two prominent theoretical frameworks dominate explanations for the IAA's biodiversity: the "centers-of hypotheses" and the "hopping hotspot hypothesis". The "centers-of hypotheses" posits that specific regions serve as key sources of IAA biodiversity, either through the accumulation and overlap of species from external areas or via elevated rates of local speciation. In contrast, the "hopping hotspot hypothesis" asserts that biodiversity hotspots are dynamic, shifting across geological timescales in response to tectonic and environmental changes. This review synthesizes these contrasting perspectives into an integrated framework, the "Dynamic Centers Hypothesis," which proposes that as biodiversity hotspots migrate over time, the IAA's role in generating and sustaining biodiversity has evolved, with varying contributions from different sources dominating distinct historical phases. By synthesizing the evidence for both hypotheses and incorporating recent findings, including fossil and phylogeography data, we propose the "Dynamic Centers Hypothesis" as a comprehensive and unifying explanation for the IAA's biodiversity. The review further explores biogeographic delineation, aligning tropical marine realms with the IAA's evolutionary trajectory, from its Tethyan roots to its modern Indo-West Pacific dominance. Looking forward, advances in DNA barcoding and genomics are uncovering vast cryptic diversity, revolutionizing our comprehension of IAA phylogeographic history. These discoveries underscore the imperative for a multidimensional conservation framework, integrating phylogenetic, and functional diversity, to preserve this biodiversity hotspot amid escalating global change.

Biogeography↗
PubMed1992

Genetic variability in the social bee Lasioglossum marginatum and a cryptic undescribed sibling species, as detected by DNA fingerprinting and allozyme electrophoresis.

DNA fingerprints (DNAfp) were obtained for three widely separated samples of bee related to Lasioglossum marginatum using the M13 sequence as a probe. Bee samples were obtained from France (three localities separated by at most 20 km), Greece and India. All European populations exhibited almost identical profiles with similarity indices (S) of over 98% within a French sample, 94% among Greek bees and 90% between Greek and French bees. The DNAfp profiles of Indian bees showed more polymorphism (intrapopulation S = 77%) and were quite dissimilar to the European samples (S = 55% and 56% to French and Greek samples, respectively). The similarity between populations separated by over 2000 km is higher than among unrelated individuals within a population in two other bee species and the tsetse fly. Data from allozyme electrophoresis shows parallel variation to that obtained with DNAfp and the genetic differences between Indian and European samples are strikingly large (Indian and European populations shared no alleles at 14 out of 47 loci surveyed) such that no more than one species must be involved. Nonetheless, the samples are indistinguishable morphologically. We argue that chronically low effective population size in these species results in low levels of genetic variability and that this, combined with a genetic bottleneck during the speciation event and colonization of Europe, may have resulted in both the extremely low levels of DNAfp variation in European bees and the large number of fixed allelic differences between European and Indian samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗