Papers by Catherine McFadden
Diversity
We document the benthic ctenophores Coeloplana sp. and Vallicula multiformis from Oman, extending... more We document the benthic ctenophores Coeloplana sp. and Vallicula multiformis from Oman, extending their geographic range. A new Coeloplana species was found forming aggregations on gorgonians of two octocoral host genera, Melithaea and Euplexaura, representing associations previously unknown to occur in the Indo-West Pacific region. Our findings also illustrate the concurrent presence of the ectocommensal ophiuroid Ophiothela mirabilis, which adversely affects other Coeloplana species in the tropical West Atlantic, where it is considered invasive. This exploration contributes to our understanding of the biogeography, species distribution, and ectosymbiotic associations of these genera, setting the stage for a comprehensive species description and in-depth analysis of host relationships in future studies.
Scientific Reports, May 8, 2023
Phylogenies of anthozoan cnidarians (e.g., corals and sea anemones) reconstructed from mt genes o... more Phylogenies of anthozoan cnidarians (e.g., corals and sea anemones) reconstructed from mt genes or genomes have often recovered relationships within and among orders that differ from those inferred from both nuclear genes and morphology. The mt genomes of these non-bilaterian metazoans have several unusual properties that are not found in bilaterians 9. For example, the mt genomes of class Hexacorallia (e.g., sea anemones, scleractinian corals and black corals) encode the standard 13 protein-coding genes found in bilaterians, but only two tRNAs (trnW, trnM) 10-14. Many hexacorals have group I introns in nad5 or cox1 10-13 , and the latter gene may have a LAGLI-DADG type homing endonuclease encoded within it 13. The ceriantharian tube anemones have multipartite linear mt genomes 15. All members of class Octocorallia (e.g., soft corals, gorgonians and sea pens) have just a single tRNA (trnM), but with only one known exception (i.e., a member of genus Pseudoanthomastus 16) their mt genomes include an additional protein-coding gene that encodes the DNA mismatch repair protein, mtMutS 17. At least one sea pen has a bipartite circular mt genome 18 , and other octocoral lineages have undergone frequent rearrangements (inversions) of gene order by a mechanism that appears to involve intramolecular recombination 19-21. The unusual property of anthozoan mt genomes that has most impacted their utility for phylogenetic reconstruction is, however, the rate at which they evolve. Unlike bilaterian mt genomes that tend to evolve 5-10X faster than the nuclear genome 22,23 , anthozoan mt genes typically evolve 10-100X slower than nuclear genes 24. As a result, mt genes that have been widely used in bilaterians for barcoding, species-level phylogenetic analyses and phylogeography are often invariant within-and sometimes between-anthozoan genera 25,26. These slow rates of mt gene evolution have, however, increased the potential utility of mt genes for reconstructing deep phylogenetic relationships among the families and orders of Anthozoa, a group of organisms that last shared a common ancestor in the pre-Cambrian 27,28. Nonetheless, phylogenies of Anthozoa reconstructed from complete mt genomes (or their protein-coding genes) have often been incongruent with other sources of morphological and phylogenomic evidence. The most notable of these discrepancies has been a lack of support for the monophyly of the anthozoan classes, Hexacorallia and Octocorallia. Mitochondrial phylogenies have often placed Octocorallia sister to the cnidarian sub-phylum Medusozoa 4,21,29,30 , despite the very strong morphological and life-history evidence for the monophyly of Anthozoa (see 31), which has also been confirmed in several phylogenomic studies 32,33. Moreover, in some of these same analyses Hexacorallia has been recovered outside of Cnidaria, as the sister to a clade of sponges 4,34. Mitochondrial gene phylogenies have also recovered Ceriantharia (tube anemones) sister to the rest of Anthozoa 15,30,35 rather than within Hexacorallia as supported by genomic-scale studies 27,28,32. In addition, previous studies have suggested that Scleractinia is paraphyletic with Corallimorpharia 4,12,36) and have differed from nuclear gene phylogenies in the placement of the orders Actiniaria, Zoantharia and Antipatharia and in the relationships among the major clades of Scleractinia 37,38. Within Octocorallia, mt genes and/or genomes have provided little statistical support for the deepest nodes in either of the two major clades that have been recognized 29,30,39,40. Explanations that have been proposed to explain the incongruence between mt and nuclear or morphological phylogenies of Anthozoa include substitution saturation of the mt genome 21,36,41 , rate heterogeneity between the major lineages 29 , and long branch attraction (LBA) due to the combined effects of rate heterogeneity and incomplete or biased taxon sampling 34. Most mt genome phylogenies and phylogenomic analyses of anthozoans published to date have been taxon-sparse, often omitting entire orders 29,32,33 or have drawn comparisons between topologies generated from completely different taxon sets 41. As a result, it is still unclear if the source of incongruence between mt and nuclear gene phylogenies of anthozoans is simply an artifact of incomplete, biased and incomparable taxon sampling or if the evolutionary signal present in anthozoan mt genomes does indeed differ from that of the nuclear genome. Recent advances in phylogenomic methods and technologies have facilitated the ability to obtain complete mt genomes while simultaneously generating sequence reads for thousands of nuclear genes. In particular, target-enrichment methods used to sequence ultraconserved elements (UCEs) and exonic regions of the nuclear genome can recover complete or near-complete mt genomes as off-target reads 3. Comparisons of mt vs nuclear gene phylogenies from the same set of taxa (often the same individuals) facilitate investigation of the causes of mt-nuclear incongruence by eliminating artifacts that may be caused by unequal or different taxon sampling. In recent phylogenomic analyses of Anthozoa based on UCEs and exons 27,28 , complete or near-complete mt genomes were recovered for a majority of the taxa sequenced. Here, we used the complete set of mt proteincoding sequences to reconstruct the phylogenies of the Octocorallia and Hexacorallia classes and compared those to nuclear gene phylogenies generated for the same set of individuals. The dataset comprised a total of 202 species representing all orders and > 50% of extant families. With this comparable dataset, the impacts of sampling biases were removed and we were able to robustly explore whether incongruence is related to evolutionary signal. New findings on the unique properties of the recovered mt genomes are also noted.
Molecular Ecology, Apr 6, 2004
Several recent studies have suggested that hybridization may play a previously unrecognized and i... more Several recent studies have suggested that hybridization may play a previously unrecognized and important role in the evolution of corals. Our observations of polymorphic and recombinant sequences in the multicopy ribosomal internal transcribed spacer (ITS) region suggested the possible hybrid origin of two European soft coral species, Alcyonium hibernicum and Bellonella bocagei. To examine this possibility further we cloned and sequenced ITS-1 from multiple individuals and populations of these two species as well as two sympatric congeners, A. coralloides and A. sp. M 2. Phylogenetic analyses separated the observed sequence variants into two distinct clades. All A. coralloides sequences belonged to clade A, while A. sp. M 2 had only clade B sequences. A majority of A. hibernicum individuals, however, contained both clade A and B sequences that were identical to the predominant sequence variants found in A. coralloides and A. sp. M 2, respectively. This pattern of additivity suggests that A. hibernicum originated from a hybrid cross between A. coralloides and A. sp. M 2, a hypothesis that is supported by its unusual mode of reproduction (meiotic parthenogenesis). The predominant sequence variant found in B. bocagei was a unique, derived clade B sequence; in addition, however, most individuals of this species also had copies of a sequence identified as a recombinant between clade A and clade B sequence types. The presence of this recombinant sequence in the B. bocagei genome suggests that this species may also be the product of past hybridization events within the clade. Reticulate evolution may explain the failure of several previous studies to resolve the phylogeny of these four species.
Bulletin of the Society of Systematic Biologists, Oct 14, 2022
<i>Sympodium subtilis</i> sp. n. Figs. 12, 13, 14A <b>Material.</b> Japan... more <i>Sympodium subtilis</i> sp. n. Figs. 12, 13, 14A <b>Material.</b> Japan. <b>Syntypes</b>: SMNHTAU_ Co _38204, Nagasaki, Danjo Islands, south of Arasesaki, Ojima, NW side (32.051168°N, 128.391857°E), 23 September 2018, 10– 20 m, coll. C. McFadden; <b>Paratypes:</b> SMNHTAU_ Co _38092 Nagasaki, Danjo Islands, Ojima, SE side (32.038886°N, 128.387278°E), 22 September 2018, 10– 20 m, coll. C. McFadden (molecular sample only); SMNHTAU_Co_38103 Nagasaki, Danjo Islands, rocks west of Yorijima (32.024824°N, 128.364289°E), 23 September 2018, 10– 20 m, coll. C. McFadden (molecular sample only); SMNHTAU_ Co _38104, same details. <b>Description</b>. The syntypes comprise several irregular encrusting colonies with a delicate thin spreading membrane (&lt;0.5 mm) attached to a bivalve shell (Fig. 12A). The largest colony has a surface area of ca. 15 mm 2. In addition, there are a few small colonies measuring 3–5 mm 2. It was not possible to separate a single colony as a holotype without compromising its integrity and therefore syntypes were assigned. The polyps emerge from the membrane 1–5 mm apart and exhibit various degrees of retraction (Fig. 12B). The few expanded polyps are up to 1.5 mm long and their tentacles are approximately 0.5 mm long. The pinnules are either totally or partially contracted, with a single row of 3–5 pinnules on either side of the tentacle. The sclerites of the syntypes are ellipsoid platelets, abundant throughout the colony and measuring 0.010 –0.012 x 0.013 –0.015 mm in diameter (Fig.13A). They are composed of densely packed calcite rods whose tips provide a uniform granular appearance to the sclerite surface (Fig. 13B). <b>Color.</b> The ethanol-preserved syntypes are light gray, almost white. <b>Etymology.</b> The species' name, <i>subtilis</i> from the Latin meaning delicate, refers to the delicate encrusting membrane of the species. <b>Variation.</b> The paratype SMNHTAU_Co_38104 is a small colony measuring only a few mm in size, but otherwise resembles the holotype. <b>Living features</b>. The [...]
Diversity, Oct 26, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Zootaxa, Dec 1, 2021
The oldest existing type material for any of the xeniid soft corals, Sympodium caeruleum Ehrenber... more The oldest existing type material for any of the xeniid soft corals, Sympodium caeruleum Ehrenberg, 1834, is re-described. An integrated analysis of molecular and morphological characters of Indo-Pacific Xeniidae support the description of seven new species of that genus. The extent of interspecific morphological variation within the genus is extensive; colonies arise from an encrusting membrane of variable thickness that can be either mat-like or may have ribbon-like extensions or irregularly shaped low mounds. The polyps can either arise separately from the membrane or may be arranged into clusters of polyps that bud off at different levels to form small branched groups. The sclerites of all species are uniformly ellipsoid platelets, abundant throughout the colony. The genetic results suggest that Sympodium species demonstrate restricted geographic ranges and regional endemism, with distinct genotypes (molecular operational taxonomic units) each mostly found at a single Indo-Pacific location. The results emphasize the importance of integrating classical taxonomy with a re-examination of original old type material and molecular phylogenetic analyses, in order to delineate species boundaries and to recognize biodiversity patterns. Â
Proceedings of the National Academy of Sciences of the United States of America, Dec 15, 2020
This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDeriva... more This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).
Systematics and Biodiversity, Apr 3, 2014
Evolution, Feb 1, 1997
... 114 CATHERINE S. MCFADDEN similar fertilization mechanisms suggest that the rapid di-lution o... more ... 114 CATHERINE S. MCFADDEN similar fertilization mechanisms suggest that the rapid di-lution of gametes in seawater probably limits the effective ... gamete dispersal is not likely to be an important mechanism of long-distance gene flow (Pennington 1985; Denny 1988; Denny ...
The Quarterly Review of Biology, Dec 1, 1987
Marine Pollution Bulletin, Mar 1, 2023
Plankton and Benthos Research, Aug 14, 2020
Sea pens are ecologically important habitats for associated marine organisms, serving as ecosyste... more Sea pens are ecologically important habitats for associated marine organisms, serving as ecosystem engineers in sandy or muddy seafloor environments. In such areas, sea pens can form habitats with high population densities known as sea pen fields. However, the presence and importance of sea pen fields have not been well studied in shallow waters in East Asia. Here, we report a sea pen field of Virgularia sp. aff. gustaviana in the shallow waters of Ushibuka Marine Park, in the Amakusa Islands of southern Japan. The average colony numbers of the field across all depths (7-20 m) was 10.3 colonies/m 2 (live colonies) to 13.6 colonies/m 2 (all: live+dead colonies+holes), and the area of the sea pen field was at least ∼50,000 m 2. At a depth of 15 m, the substratum consisted of sand and fallen leaves of terrestrial origin, and the highest sea pen density was observed (averages=17.2 live colonies/m 2 , =25.8 total (live+dead+holes) colonies/m 2). At a depth of 20 m, the substratum consisted of broken shells and rocks and had the lowest density (live colonies: average=0.8 colonies/m 2 , all: average=1.0 colonies/m 2). There were significant differences in colony number of Virgularia sp. aff. gustaviana between the sand , sand+leaves , and broken shells/rocks substrates. We hypothesize that the strength of the water currents caused by local geographic features and tidal movements produce suitable sedimentation and habitat for this species of sea pen. Therefore, we suggest that preserving the natural coastline is crucial to protect this and other sea pen fields in shallow waters and their benthic marine communities.
BMC Evolutionary Biology, Jun 6, 2019
Background: Our ability to investigate processes shaping the evolutionary diversification of cora... more Background: Our ability to investigate processes shaping the evolutionary diversification of corals (Cnidaria: Anthozoa) is limited by a lack of understanding of species boundaries. Discerning species of corals has been challenging due to a multitude of factors, including homoplasious and plastic morphological characters and the use of molecular markers that are either not informative or have not completely sorted. Hybridization can also blur species boundaries by leading to incongruence between morphology and genetics. We used traditional DNA barcoding and restriction-site associated DNA sequencing combined with coalescence-based and allele-frequency methods to elucidate species boundaries and simultaneously examine the potential role of hybridization in a speciose genus of octocoral, Sinularia. Results: Species delimitations using two widely used DNA barcode markers, mtMutS and 28S rDNA, were incongruent with one another and with the morphospecies identifications. When mtMutS and 28S were concatenated, a 0.3% genetic distance threshold delimited the majority of morphospecies. In contrast, 12 of the 15 examined morphospecies formed well-supported monophyletic clades in both concatenated RAxML phylogenies and SNAPP species trees of > 6000 RADSeq loci. DAPC and Structure analyses also supported morphospecies assignments, but indicated the potential for two additional cryptic species. Three morphologically distinct species pairs could not, however, be distinguished genetically. ABBA-BABA tests demonstrated significant admixture between some of those species, suggesting that hybridization may confound species delimitation in Sinularia. Conclusions: A genomic approach can help to guide species delimitation while simultaneously elucidating the processes generating coral diversity. Results support the hypothesis that hybridization is an important mechanism in the evolution of Anthozoa, including octocorals, and future research should examine the contribution of this mechanism in generating diversity across the coral tree of life.
ZooKeys, May 23, 2017
An octocoral survey conducted in the mesophotic coral ecosystem (MCE) of Eilat (Gulf of Aqaba, no... more An octocoral survey conducted in the mesophotic coral ecosystem (MCE) of Eilat (Gulf of Aqaba, northern Red Sea) yielded a new species of the speciose reef-dwelling genus Sinularia. It features encrusting colony morphology with a thin, funnel-shaped polypary. Sinularia mesophotica sp. n. (family Alcyoniidae) is described and compared to the other congeners with similar morphology. Both the morphological and molecular examination justified the establishment of the new species, also assigning it to a new genetic clade within Sinularia. The results highlight its unique phylogenetic position within the genus, and this is the first described species of a mesophotic zooxanthellate octocoral.
Journal of Natural History, Dec 16, 2009
Acanthoaxis wirtzi, a new genus and new species of octocoral, is described and depicted for speci... more Acanthoaxis wirtzi, a new genus and new species of octocoral, is described and depicted for specimens collected in shallow water off Botha Island, Cameroon, West Africa. A new family, Acanthoaxiidae, is proposed to accommodate the new genus. The characters of this family are the total lack of sclerites; the axis having a narrow, hollow, soft, cross-chambered central core; and the
ZooKeys, Aug 5, 2014
A survey of xeniid octocorals was carried out in the waters off Southwestern Thailand in Septembe... more A survey of xeniid octocorals was carried out in the waters off Southwestern Thailand in September, 2007. Microscopic investigation of the colonies revealed that three specimens belonged to the genus Ovabunda. Gross morphological examination is presented here accompanied by scanning electron micrographs of the sclerites. Molecular phylogenetic analysis showed identical genotypes at mtMutS, COI, and 28S rDNA for all three specimens and supports their generic assignment. Colony size and shape, sclerite size, and pinnule arrangement differ from nominal species of Ovabunda and thus a new species, O. andamanensis is introduced here. This work also presents a new eastern geographical record for the genus Ovabunda.
ZooKeys, May 2, 2018
Several species of the family Xeniidae, previously assigned to the genus Cespitularia Milne Edwar... more Several species of the family Xeniidae, previously assigned to the genus Cespitularia Milne Edwards & Haime, 1850 are revised. Based on the problematical identity and status of the type of this genus, it became apparent that the literature has introduced misperceptions concerning its diagnosis. A consequent examination of the type colonies of Cespitularia coerulea May, 1898 has led to the establishment of the new genus Conglomeratusclera gen. n. and similarly to the assignment of Cespitularia simplex Thomson & Dean, 1931 to the new genus, Caementabunda gen. n. Both new genera are described and depicted and both feature unique sclerite morphology, further highlighting the importance of sclerite microstructure for generic position among Xeniidae. Freshly collected material was subjected to molecular phylogenetic analysis, whose results substantiated the taxonomic assignment of the new genera, as well as the synonymies of several others.
ZooKeys, Feb 25, 2013
Sinularia leptoclados (Ehrenberg, 1834) is re-described. Sinularia leptoclados var. gonatodes Kol... more Sinularia leptoclados (Ehrenberg, 1834) is re-described. Sinularia leptoclados var. gonatodes Kolonko, 1926 is synonymized with S. maxima Verseveldt, 1977. Two new species of Sinularia with digitiform lobules, leptoclados-type surface clubs and unbranched interior spindles, are described. An updated maximum likelihood tree of Sinularia species with leptoclados-type clubs (clade 5C) based on two mitochondrial genes (mtMutS, COI) and a nuclear gene (28S rDNA) is presented.
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Papers by Catherine McFadden