Swedish Museum of Natural History
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Ephemeral Speciation in a New Guinean Honeyeater Complex ( Aves : Melidectes )
No full textSpeciation is a fundamental concept in evolutionary biology, and understanding the mechanisms driving speciation remains the foremost research topic within this field. Hybridisation is often involved in speciation and can influence its rates, potentially accelerating, decelerating or even reversing the process. This study investigates the evolutionary history of the New Guinean bird genus Melidectes, consisting of six species that inhabit various montane regions at different elevations. While most Melidectes species have allopatric distributions, two species overlap in the central mountain range and hybridise. However, plumage differences and elevational adaptations are assumed to maintain the species' boundaries. Utilising specimens from natural history collections and comprehensive genomic analyses, including a de novo genome assembly, we characterise allopatric speciation patterns within the genus and highlight how future speciation could potentially be driven by climate change. Contrary to previous hypotheses, our findings suggest that in the two distributionally overlapping species, phenotypic differences do not prevent gene flow. We find limited acoustic differentiation and extensive admixture across most of their distributions. Divergence and admixture levels conform poorly to the current taxonomy and follow a geographical pattern in which the most isolated populations at the ends of the distributions are most divergent and show least admixture. However, in contrast, their mitochondrial genomes do group in accordance with species identity, namely, into two deeply divergent lineages. We propose that this system demonstrates the ephemeral nature of speciation, in which two incipient species have started mixing extensively as they came into secondary contact, resulting in nearly complete fusion into a single lineage
Genomics Sheds New Light on the Ancestral Bilaterian Opsin Repertoire and Suggests Rhabdomeric Phototransduction in Xenacoelomorpha
No full textRevision of the Indo-Pacific species of the genus Leucosyrinx Dall, 1889 (Neogastropoda: Conoidea: Pseudomelatomidae)
No full textThe genus Leucosyrinx Dall, 1889 is one of the highly diverse genera of the familyPseudomelatomidae, distributed across the Atlantic and Pacific Oceans. It remains poorly defined basedon conchological characters. The last revision of the genus was published by Powell (1969; Indo-PacificMollusca 2 (10): 207–415), in which many species were erroneously included, while others belongingto Leucosyrinx were attributed to different genera. For the first time, we have revised the Indo-Pacificspecies of the genus within the framework of integrative taxonomy, utilizing molecular-grade materialaccumulated in the Muséum national d’Histoire naturelle, France. Molecular phylogenetic analysisrevealed the existence of 62 secondary species hypotheses (SSHs) in our material, with 12 of themcorresponding to already named species. The remaining 50 SSHs represent new species, of which 24are described here, while 26 remain unnamed due to insufficient material. We refined the morphologicalcharacteristics of Leucosyrinx based on shell analysis of sequenced species from the genus, as well asfrom similar genera, particularly Comitas, Sibogasyrinx, and Comispira (the latter two belonging toCochlespiridae). This allowed us to assign 18 previously named species to Leucosyrinx, and conditionallyattribute four more, bringing the total number of species in the Indo-Pacific to 84, of which 58 are named.Numerous cases of cryptic species, which are nearly indistinguishable morphologically, were recordedwithin Leucosyrinx. The genus is confined to the upper bathyal zone, ranging from 195 to 1634 m indepth, with most occurrences between 500 and 1000 m. The highest species richness (30 species) wasrecorded in Papua New Guinea and the Solomon Islands, though this is likely due to more intensivesampling of the upper bathyal zone in these regions compared to other areas of the Indo-Pacific
Genome analyses suggest recent speciation and postglacial isolation in the Norwegian lemming
No full textThe Norwegian lemming (Lemmus lemmus) is a small rodent distributed across theFennoscandian mountain tundra and the Kola Peninsula. The Norwegian lemming likelyevolved during the Late Pleistocene and inhabited Fennoscandia shortly prior to the LastGlacial Maximum. However, the exact timing and origins of the species, and its phyloge-netic position relative to the closely related Siberian lemming (Lemmus sibiricus) remaindisputed. Moreover, the presence of ancient or contemporary gene flow between bothspecies is largely untested. The Norwegian lemming displays characteristic phenotypicand behavioral adaptations (e.g., coat color, aggression) that are not present in otherLemmus species. We generated a de novo genome assembly for the Norwegian lemmingand resequenced nine modern and two ancient Lemmus spp. genomes. We show that allLemmus species form distinct monophyletic clades, with concordant topology betweenthe mitochondrial and nuclear genome phylogenies. The Siberian lemming is dividedinto two distinct but paraphyletic clades, one in the east and one in the west, where thewestern clade represents a sister taxon to the Norwegian lemming. We estimate thatthe Norwegian and western Siberian lemming diverged shortly before the Last GlacialMaximum, making the Norwegian lemming one of the youngest known mammalianspecies. We did not find any indication of gene flow between L. lemmus and L. sibiricus,suggesting postglacial isolation of L. lemmus. Furthermore, we identify species-specificgenomic differences in genes related to coat color and fat transport, which are likelyassociated with the distinctive coloration and overwintering behavior observed in theNorwegian lemming
Environmental DNA from peck marks shows potential for non‑invasive monitoring of woodpeckers
No full textMonitoring species’ occurrences is essential for understanding ecosystem dynamics, tracking biodiversity changes, and guiding conservation efforts. Traditional monitoring methods, such as visual surveys, are challenging, particularly for elusive and endangered species. This proof-of-concept study explores the potential of environmental DNA (eDNA) collected from peck marks as a non-invasive tool for detecting and identifying woodpecker species. We collected nine samples from fresh peck marks on birch and spruce trees in the forests of Swedish Lapland. In two samples, we successfully amplified an 81 base-pair fragment of the woodpecker mitochondrial 16S rRNA gene. Taxonomic assignment identified the Eurasian three-toed woodpecker (Picoides tridactylus), a species classified as “Near Threatened” in Sweden. We collected an additional 15 samples from 4-19 years old peck marks preserved inside the trunks of birch and pine trees in the same area. No woodpecker DNA was detected in these samples, likely due to DNA degradation. Our findings demonstrate the potential of using eDNA from peck marks as a non-invasive approach for monitoring elusive woodpecker specie
Chromosome-level genome assembly of Norwegian wild alpine reindeer (Rangifer tarandus tarandus)
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