Limits...
Conservation genetics of a critically endangered limpet genus and rediscovery of an extinct species.

Ó Foighil D, Li J, Lee T, Johnson P, Evans R, Burch JB - PLoS ONE (2011)

Bottom Line: It persists in a Coosa River tributary and morphometric and phylogenetic analyses confirm its taxonomic validity.All three surviving populations of the genus Rhodacmea merit specific status.We recommend the establishment of a proactive targeted conservation program that may include their captive propagation and reintroduction.

View Article: PubMed Central - PubMed

Affiliation: Museum of Zoology and Department of Ecology and Evolutionary Biology, The University of Michigan, Ann Arbor, Michigan, United States of America. diarmaid@umich.edu

ABSTRACT

Background: A third of all known freshwater mollusk extinctions worldwide have occurred within a single medium-sized American drainage. The Mobile River Basin (MRB) of Alabama, a global hotspot of temperate freshwater biodiversity, was intensively industrialized during the 20(th) century, driving 47 of its 139 endemic mollusk species to extinction. These include the ancylinid limpet Rhodacmea filosa, currently classified as extinct (IUCN Red List), a member of a critically endangered southeastern North American genus reduced to a single known extant population (of R. elatior) in the MRB.

Methodology/principal findings: We document here the tripling of known extant populations of this North American limpet genus with the rediscovery of enduring Rhodacmea filosa in a MRB tributary and of R. elatior in its type locality: the Green River, Kentucky, an Ohio River Basin (ORB) tributary. Rhodacmea species are diagnosed using untested conchological traits and we reassessed their systematic and conservation status across both basins using morphometric and genetic characters. Our data corroborated the taxonomic validity of Rhodacmea filosa and we inferred a within-MRB cladogenic origin from a common ancestor bearing the R. elatior shell phenotype. The geographically-isolated MRB and ORB R. elatior populations formed a cryptic species complex: although overlapping morphometrically, they exhibited a pronounced phylogenetic disjunction that greatly exceeded that of within-MRB R. elatior and R. filosa sister species.

Conclusions/significance: Rhodacmea filosa, the type species of the genus, is not extinct. It persists in a Coosa River tributary and morphometric and phylogenetic analyses confirm its taxonomic validity. All three surviving populations of the genus Rhodacmea merit specific status. They collectively contain all known survivors of a phylogenetically highly distinctive North American endemic genus and therefore represent a concentrated fraction of continental freshwater gastropod biodiversity. We recommend the establishment of a proactive targeted conservation program that may include their captive propagation and reintroduction.

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Related in: MedlinePlus

Left-lateral and dorsal views of exemplar Rhodacmea spp. shells.Specimens from both extant Rhodacmea elatior populations (Green River; Cahaba River) are shown. Two specimens from the single extant R. filosa population (Choccolocco Creek, the individual on the left has lost its apex) are also depicted, in addition to a century old museum exemplar (Tallaseehatchee Creek; UMMZ 69215).
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pone-0020496-g002: Left-lateral and dorsal views of exemplar Rhodacmea spp. shells.Specimens from both extant Rhodacmea elatior populations (Green River; Cahaba River) are shown. Two specimens from the single extant R. filosa population (Choccolocco Creek, the individual on the left has lost its apex) are also depicted, in addition to a century old museum exemplar (Tallaseehatchee Creek; UMMZ 69215).

Mentions: Figure 2 shows lateral and dorsal views of exemplar limpets sampled from all three extant populations (Fig. 1) together with a century old museum reference specimen of Rhodacmea filosa (UMMZ 69215) from Tallaseehatchee Creek, another Coosa tributary. Green River and Cahaba River limpets all exhibited diagnostic R. elatior conchological features: elevated patelliform shells that lack ribbing and have clearly convex anterior slopes [16], [36]. Limpets from Choccolocco Creek, a Coosa River tributary, were much smaller and all unambiguously displayed the diagnostic feature of R. filosa: ribbing in the form of strong radiating lines running from the apex to the aperture [16], [37]. None of the limpets matched the description of R. hinkleyi (Walker, 1908), the third nominal member of this genus [16].


Conservation genetics of a critically endangered limpet genus and rediscovery of an extinct species.

Ó Foighil D, Li J, Lee T, Johnson P, Evans R, Burch JB - PLoS ONE (2011)

Left-lateral and dorsal views of exemplar Rhodacmea spp. shells.Specimens from both extant Rhodacmea elatior populations (Green River; Cahaba River) are shown. Two specimens from the single extant R. filosa population (Choccolocco Creek, the individual on the left has lost its apex) are also depicted, in addition to a century old museum exemplar (Tallaseehatchee Creek; UMMZ 69215).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105076&req=5

pone-0020496-g002: Left-lateral and dorsal views of exemplar Rhodacmea spp. shells.Specimens from both extant Rhodacmea elatior populations (Green River; Cahaba River) are shown. Two specimens from the single extant R. filosa population (Choccolocco Creek, the individual on the left has lost its apex) are also depicted, in addition to a century old museum exemplar (Tallaseehatchee Creek; UMMZ 69215).
Mentions: Figure 2 shows lateral and dorsal views of exemplar limpets sampled from all three extant populations (Fig. 1) together with a century old museum reference specimen of Rhodacmea filosa (UMMZ 69215) from Tallaseehatchee Creek, another Coosa tributary. Green River and Cahaba River limpets all exhibited diagnostic R. elatior conchological features: elevated patelliform shells that lack ribbing and have clearly convex anterior slopes [16], [36]. Limpets from Choccolocco Creek, a Coosa River tributary, were much smaller and all unambiguously displayed the diagnostic feature of R. filosa: ribbing in the form of strong radiating lines running from the apex to the aperture [16], [37]. None of the limpets matched the description of R. hinkleyi (Walker, 1908), the third nominal member of this genus [16].

Bottom Line: It persists in a Coosa River tributary and morphometric and phylogenetic analyses confirm its taxonomic validity.All three surviving populations of the genus Rhodacmea merit specific status.We recommend the establishment of a proactive targeted conservation program that may include their captive propagation and reintroduction.

View Article: PubMed Central - PubMed

Affiliation: Museum of Zoology and Department of Ecology and Evolutionary Biology, The University of Michigan, Ann Arbor, Michigan, United States of America. diarmaid@umich.edu

ABSTRACT

Background: A third of all known freshwater mollusk extinctions worldwide have occurred within a single medium-sized American drainage. The Mobile River Basin (MRB) of Alabama, a global hotspot of temperate freshwater biodiversity, was intensively industrialized during the 20(th) century, driving 47 of its 139 endemic mollusk species to extinction. These include the ancylinid limpet Rhodacmea filosa, currently classified as extinct (IUCN Red List), a member of a critically endangered southeastern North American genus reduced to a single known extant population (of R. elatior) in the MRB.

Methodology/principal findings: We document here the tripling of known extant populations of this North American limpet genus with the rediscovery of enduring Rhodacmea filosa in a MRB tributary and of R. elatior in its type locality: the Green River, Kentucky, an Ohio River Basin (ORB) tributary. Rhodacmea species are diagnosed using untested conchological traits and we reassessed their systematic and conservation status across both basins using morphometric and genetic characters. Our data corroborated the taxonomic validity of Rhodacmea filosa and we inferred a within-MRB cladogenic origin from a common ancestor bearing the R. elatior shell phenotype. The geographically-isolated MRB and ORB R. elatior populations formed a cryptic species complex: although overlapping morphometrically, they exhibited a pronounced phylogenetic disjunction that greatly exceeded that of within-MRB R. elatior and R. filosa sister species.

Conclusions/significance: Rhodacmea filosa, the type species of the genus, is not extinct. It persists in a Coosa River tributary and morphometric and phylogenetic analyses confirm its taxonomic validity. All three surviving populations of the genus Rhodacmea merit specific status. They collectively contain all known survivors of a phylogenetically highly distinctive North American endemic genus and therefore represent a concentrated fraction of continental freshwater gastropod biodiversity. We recommend the establishment of a proactive targeted conservation program that may include their captive propagation and reintroduction.

Show MeSH
Related in: MedlinePlus