skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Origin and Biogeography of the Colourful Sap‐Sucking Sea Slugs Genus Thuridilla Bergh, 1872 (Mollusca, Gastropoda, Heterobranchia)
Title: Origin and Biogeography of the Colourful Sap‐Sucking Sea Slugs Genus Thuridilla Bergh, 1872 (Mollusca, Gastropoda, Heterobranchia)
ABSTRACT AimThuridillaBergh, 1872, is a lineage of herbivorous sea slugs externally distinguished by bright colours and distinctive patterns of lines and spots. Recent work revealed an exceptionally rapid, cryptic radiation of 13 species in the Indo‐Pacific, raising questions about mechanisms of speciation in this group. Here, we (i) study the diversification and historical biogeography ofThuridillain a phylogenetic context and (ii) assess the role of dispersal and vicariance as the predominant mode of speciation in the genus. LocationTropical and temperate regions of the Atlantic and Indo‐Pacific. Major Taxa StudiesGastropoda, Sacoglossa. MethodsA nearly complete taxon set with 28 out of 32 recognised species ofThuridillawas used, in a total sample of 172 specimens, together with sacoglossan outgroups. Phylogenetic relationships were determined using a multi‐locus approach combining two mitochondrial (COI and 16S) and one nuclear gene (H3). Species relationships, diversification times, and ancestral geographical ranges were inferred using relaxed‐clock methods together with Bayesian discrete phylogeographic methods under three calibration scenarios using the oldest known fossil of Sacoglossa,Berthelinia elegansCrosse, 1875, and tectonic events. ResultsThuridillaspecies branched off into four major clades in all calibration scenarios: two groups from the Atlantic plus Indo‐West Pacific (5 and 6 species) and two clades from the Indo‐West Pacific (4 and 17 species). The highest diversity of the genus is in the Western Pacific (14 spp.) with a peak in the East Indies Triangle (18 spp.), whereas the Atlantic is depauperate with only four species occurring in this ocean basin. Divergence between Atlantic and Indo‐West Pacific lineages occurred in two main temporal periods: the Miocene and the Pliocene. Speciation events within the 13 cryptic species‐complex fell mostly within Plio‐Pleistocene times. Main ConclusionsThe best supported hypothesis was an Indo‐West Pacific origin ofThuridillabetween 28 and 18 Mya during the Early Miocene. In the western Pacific, speciation likely occurred during transient allopatry during Plio‐Pleistocene sea‐level fluctuations. Under the three tested calibration scenarios, the limited diversity of the Atlantic Ocean is hypothesized to be derived from Miocene vicariant events associated with the closure of the Tethys Sea, dispersal across southern Africa, or long‐distance dispersal across the East Pacific Barrier prior to the uplift of the Isthmus of Panama.Thuridillais absent in the Eastern Pacific, potentially resulting from the extinction of ancestral lineages following the uplift of the Isthmus of Panama. Near‐complete sampling of diversity and reconstruction of historical biogeography thus yielded new insight into the relative contributions of dispersal versus vicariance during speciation over the history of this widely distributed, colourful genus.  more » « less
Award ID(s):
2127110
PAR ID:
10621879
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Journal of Biogeography
Date Published:
Journal Name:
Journal of Biogeography
ISSN:
0305-0270
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; (, Coral Reefs - this is not a proceedings, it is a journal, but it is not in your dropdown!?)
    null (Ed.)
    Coral reefs are home to the greatest diversity of marine life, and many species on reefs live in symbiotic associations. Studying the historical biogeography of symbiotic species is key to unravelling (potential) coevolutionary processes and explaining species richness patterns. Coral-dwelling gall crabs (Cryptochiridae) live in obligate symbiosis with a scleractinian host, and are ideally suited to study the evolutionary history between heterogeneous taxa involved in a symbiotic relationship. The genus Opecarcinus Kropp and Manning, 1987, like its host coral family Agariciidae, occurs in both Indo-Pacific and Caribbean seas, and is the only cryptochirid genus with a circumtropical distribution. Here, we use mitochondrial and nuclear DNA gene fragments of Opecarcinus specimens sampled from 21 Indo-Pacific localities and one Atlantic (Caribbean) locality. We applied several species delimitation tests to characterise species diversity, inferred a Bayesian molecular-clock time-calibrated phylogeny to estimate divergence times and performed an ancestral area reconstruction. Time to the most recent common ancestor (tMRCA) of Opecarcinus is estimated at 15−6 Mya (middle Miocene—late Miocene). The genus harbours ~ 15 undescribed species as well as several potential species complexes. There are indications of strict host-specificity patterns in certain Opecarcinus species in the Indo-Pacific and Atlantic, however, a robust phylogeny reconstruction of Agariciidae corals—needed to test this further—is currently lacking. The Indo-West Pacific was inferred to be the most probable ancestral area, from where the Opecarcinus lineage colonised the Western Atlantic and subsequently speciated into O. hypostegus. Opecarcinus likely invaded from the Indo-West Pacific across the East Pacific Barrier to the Atlantic, before the full closure of the Isthmus of Panama. The subsequent speciation of O. hypostegus, is possibly associated with newly available niches in the Caribbean, in combination with genetic isolation following the closure of the Panama Isthmus. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; (, Journal of Biogeography)
    ABSTRACT AimThe aim of the current study is to conduct a comprehensive phylogenetic analysis of the genusArbaciato elucidate the evolution and phylogenetic relationships among all extant species and reevaluate the presence of geographic structure within species that have wide, fragmented distributions. LocationSpecimens ofArbaciawere collected from 34 localities spanning the Atlantic and Pacific Oceans, and the Mediterranean Sea. MethodsWe obtained sequences from three mitochondrial markers (COI, 16S and the control region and adjacent tRNAs) and two nuclear markers (28S and 18S; the latter ultimately excluded from the final analyses). Phylogenetic trees were constructed using maximum likelihood and Bayesian inference approaches. A time‐calibrated phylogenetic tree was inferred using a relaxed Bayesian molecular clock and three fossil calibration points. ResultsOur analysis supports the monophyly of the genusArbacia, including the speciesArbacia nigra(previously assigned to the monotypic genusTetrapygus). The new phylogenetic topology suggests an alternative biogeographic scenario of initial divergence between Atlantic and Pacific subclades occurring approximately 9 million years ago. The dispersal and subsequent diversification of the Pacific subclade to the southeast Pacific coincides with the onset of glacial and interglacial cycles in Patagonia. In the Atlantic subclade, the split betweenA. punctulataandA. lixulaoccurred 3.01–6.30 (median 3.74 million years ago), possibly associated with the strengthening of the Gulf Stream current connecting the western and eastern Atlantic. Our study also reveals significant genetic and phylogeographic structures within both Atlantic species, indicating ongoing differentiation processes between populations. Main ConclusionOur study provides valuable insights into the evolutionary history and biogeography of the genusArbaciaand highlights the complex interplay between historical climate changes and oceanic currents in shaping the distribution and diversification of echinoids in the Atlantic and Pacific Oceans. 
    more » « less
  3. ; ; ; ; ; ; (, Journal of Biogeography)
    Abstract AimWe studied the niche evolution and diversification modes in transisthmianAlpheusshrimps by examining the interplay between environmental niche divergence and conservatism in allopatric sister species. In a broader perspective, the current study analysed the evolution of climatic niche and the role of the environment in species diversification ofAlpheustransisthmian shrimp. LocationAtlantic and Eastern‐Pacific oceans. TaxonAlpheusshrimps (Caridea: Alpheidae). MethodsWe assembled georeferenced occurrences for 33 species ofAlpheus(with 24 sister species) from a time‐calibrated molecular phylogeny. We modelled their ecological niches and assessed niche overlap through pairwise comparisons. Additionally, we performed phylogenetic reconstructions of the ancestral environmental niche, for each niche axis. ResultsOur results demonstrate that thermal tolerances, food availability and hydrodynamic forces were relevant environmental axes in evolutionary processes in transisthmian species ofAlpheus. Among the 528 paired comparisons, we found that most niches were divergent, including in 12 clades formed by pairs of sister species (in only two of these clades were the niches fully equivalent). Phylogenetic reconstructions of ancestral niches showed an initial niche conservatism in all axes, with divergences intensifying in the last 12 million years. Main ConclusionsWe found evidence that confirms the relevance of the environmental changes that occurred in the West Atlantic and East Pacific for niche evolution in transisthmianAlpheusspecies, as well as for the emergence of some lineages. Our findings provide evidence for different modes ofAlpheusspecies speciation in a period consistent with the closure of the Isthmus of Panama. 
    more » « less
  4. ; ; ; ; ; ; (, American Journal of Botany)
    Abstract PremiseThe historical biogeography of ferns is typically expected to be dominated by long‐distance dispersal due to their minuscule spores. However, few studies have inferred the historical biogeography of a large and widely distributed group of ferns to test this hypothesis. Our aims were to determine the extent to which long‐distance dispersal vs. vicariance have shaped the history of the fern family Blechnaceae, to explore ecological correlates of dispersal and diversification, and to determine whether these patterns differ between the northern and southern hemispheres. MethodsWe used sequence data for three chloroplast loci to infer a time‐calibrated phylogeny for 154 of 265 species of Blechnaceae, including representatives of all genera in the family. This tree was used to conduct ancestral range reconstruction and stochastic character mapping, estimate diversification rates, and identify ecological correlates of diversification. ResultsBlechnaceae originated in Eurasia and began diversifying in the late Cretaceous. A lineage comprising most extant diversity diversified principally in the austral Pacific region around the Paleocene–Eocene Thermal Maximum. Land connections that existed near the poles during periods of warm climates likely facilitated migration of several lineages, with subsequent climate‐mediated vicariance shaping current distributions. Long‐distance dispersal is frequent and asymmetrical, with New Zealand/Pacific Islands, Australia, and tropical America being major source areas. ConclusionsAncient vicariance and extensive long‐distance dispersal have shaped the history of Blechnaceae in both the northern and southern hemispheres. The exceptional diversity in austral regions appears to reflect rapid speciation in these areas; mechanisms underlying this evolutionary success remain uncertain. 
    more » « less
  5. ; ; ; ; ; (, Diversity)
    We document aggregations of an undescribed benthic solitary tunicate of the family Pyuridae from the Arabian Sea. This new genus was found forming dense thickets in shallow rocky substrates around Masirah Island and the Dhofar area in Oman. Such aggregations of tunicates have not been reported before from coral reefs in the Indo-West Pacific region and the Atlantic. This observation contributes to our understanding of the ecology and biogeography of ascidians, setting the stage for a comprehensive species description and in-depth analysis of this species. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email