Coral barnacles: Cenozoic decline and extinction in the Atlantic/East Pacific versus diversification in the Indo-West Pacific

Proceedings of the 9th Int. Coral Reef Symposium, Bali, Indonesia 01/2002; I.


The pyrgomatid coral barnacles, first appearing in the late Oligocene of the western Atlantic, underwent a Miocene diversification unparalleled by any other group of sessile barnacles. Diversification in the Indo- Pacific (eastern Tethys) coincided with retreat of the tropics from higher latitudes, especially in the Atlantic. Fragmentation of the tropics, due to the breakup of the Tethys seaway, and wholesale extinctions of their host corals beginning in the Oligocene of Europe, Mediterranean and eastern Pacific resulted in relictual distributions and regional endemism. This was followed by Neogene extinctions of many host coral genera in the western Atlantic which were not replaced by originations. The exceptional diversity of pyrgomatids now evident in the Indo-Pacific was tied to the survival and radiation of the corals found there. Curiously, our knowledge of pyrgomatid numbers and diversity has shifted from the Indonesian to peripheral centers of distribution.

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    • "Fossil pyrgomatines are known from the late Miocene, Pleistocene, and Holocene of the IWP. All pyrgomatine fossils have been classed into extant species of Pyrgomatini (Asami & Yamaguchi, 1997; Ross & Newman, 2002a). The Megatrematinae Holthuis 1982 is a small subfamily (4 genera, 6 extant species; Table 1) distributed in the WA, IWP, and East Atlantic (EA). "
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    ABSTRACT: Pyrgomatid barnacles are a family of balanomorphs uniquely adapted to symbiosis on corals. The evolution of the coral-dwelling barnacles is explored using a multi-gene phylogeny (COI, 16S, 12S, 18S, and H3) and phenotypic trait-mapping. We found that the hydrocoral associate Wanella should be excluded, while some archaeobalanids in the genus Armatobalanus should be included in the Pyrgomatidae. Three well supported clades were recovered: clade I is the largest group and is exclusively Indo-West Pacific, clade II contains two plesiomorphic Indo-West Pacific genera, while clade III is comprised of East and West Atlantic taxa. Some genera did not form reciprocally monophyletic groups, while the genus Trevathana was found to be paraphyletic and to include members of three other apomorphic genera/tribes. The highly unusual coral-parasitic hoekiines appear to be of recent origin and rapidly evolving from Trevathana sensu lato. Pyrgomatids include six-, four-, and one-plated forms, and exhibit convergent evolutionary tendencies towards skeletal reduction and fusion, loss of cirral armature, and increased host specificity. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, ●●, ●●–●●.
    Biological Journal of the Linnean Society 08/2014; 113(1). DOI:10.1111/bij.12315 · 2.26 Impact Factor
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    • "The coralinhabiting barnacles of the sub-family Pyrgomatinae are obligatory symbionts of scleractinian corals in the Indo-Pacific. There are more than 70 nominal species of coral-inhabiting barnacles in the family Pyrgomatidae (Ross and Newman, 2003); a number that is now rising due to use of modern research technologies such as resolution morphology techniques (SEM) and molecular analysis (Mokady et al., 1999; Mokady and Brickner, 2001; Simon-Blecher et al., 2007; Achituv et al., 2009; Chan et al., 2009). The study of life-history strategies integrates physiological, morphological, and behavioral traits in order to explain how different mechanisms allocate finite resources to maintenance, growth and reproduction, under both predictable and unpredictable environments. "
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    ABSTRACT: Barnacles are one of the most common and well-studied groups in marine ecology. In the Gulf of Eilat, the barnacle assemblages in the subtidal zone are dominated by epibionts, inhabiting stony corals, hydrozoans and sponges. Pyrgomatidae barnacles are obligatory symbionts of scleractinian corals and hydrozoans. For many organisms there is a relationship between life strategies, as predicted by the r–K selection theory, and degree of habitat specialization. Earlier studies have suggested that coral-inhabiting barnacles exhibit a tendency towards the r-endpoint. In the present research we studied the life strategy of two pyrgomatidae: Trevathana sarae, a host specialist; and Cantelius pallidus, considered a host generalist, both of which occur on the same coral host, Cyphastrea chalcidicum. Our results indicate that the two species of barnacles present two different life strategies. T. sarae fits more into the K-strategy model: a slow development, late maturity (2 years), long life span (6 years), large embryos 440 μ, and a low number of propagules (ca. 40). In contrast, C. pallidus exhibits the r-selected traits: a fast development, early maturity (1 year), short life span (2 years), small embryos 270 μ, and a high number of propagules (ca. 300). These findings support the hypothesis that associates the tendency of a species strategy towards the r-or K-endpoint with the degree of habitat specialization. Furthermore, the results highlight the diversity of life strategies existing in the Pyrgomatidae.
    Journal of Experimental Marine Biology and Ecology 08/2010; 392(1). DOI:10.1016/j.jembe.2010.04.022 · 1.87 Impact Factor
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    • "In contrast, the Pyrgomatinae are Indo-Pacific and possess a wide range of characteristics, varying from a four-plated wall and four opercular valves to a single plated shell and fused scuta and terga. The Archaeobalanidae and the Balanidae possess a six-plated wall and four opercular valves; it is therefore generally agreed that fused wall-plates and fused opercular valves represent derived character states (Ross and Newman, 2002). Ogawa and Matsuzaki (1992) suggested that a single fused shell plate is the plesiomorphic condition. "
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    ABSTRACT: The traditional phylogeny of the coral-inhabiting barnacles, the Pyrgomatidae, is based on morphological characteristics, mainly of the hard parts. It has been difficult to establish the phylogenetic relationships among Pyrgomatidae because of the apparent convergence of morphological characteristics, and due to the use of non-cladistic systematics, which emphasize ancestor-descendant relationships rather than sister-clade relationships. We used partial sequences of two mithochondrial genes, 12S rDNA and 16S rDNA, and a nuclear gene, 18S rDNA, to infer the molecular phylogeny of the pyrgomatids. Our phylogenetic results allowed us to reject previous classifications of Pyrgomatidae based on morphological characteristics. Our results also suggested the possibility of paraphyly of the Pyrgomatidae. The hydrocoral barnacle Wanella is not found on the same clade as the other pyrgomatids, but rather, with the free-living balanids. The basal position of Megatrema and Ceratoconcha is supported. The archeaobalanid Armatobalanus is grouped with Cantellius at the base of the Indo-Pacific pyrgomatines. Fusion of the shell plate and modification of the opercular valves are homoplasious features that occurred more than three times on different clades. The monophyly of the "Savignium" group, comprising four nominal genera, is also not supported, and the different taxa are placed on different clades.
    Molecular Phylogenetics and Evolution 10/2007; 44(3):1333-41. DOI:10.1016/j.ympev.2007.03.026 · 3.92 Impact Factor
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