Review of the genetics, dispersal and recruitment of crown-of-thorns starfish (Acanthaster planci)

1992 ◽  
Vol 43 (3) ◽  
pp. 597 ◽  
Author(s):  
JAH Benzie
Keyword(s):  
Gene Flow ◽  
Indian Ocean ◽  
Genetic Differentiation ◽  
Primary Source ◽  
Acanthaster Planci ◽  
Genetic Structuring ◽  
West Pacific ◽  
North West ◽  
The Pacific ◽  
Western Australian

The lack of genetic structuring reported for Acanthaster planci (L.) from major biogeographical zones (i.e. Indian Ocean versus Pacific) may reflect a lack of data rather than confirmation of a recent and rapid dispersal of the species worldwide. The low level of genetic variation among A. planci populations throughout the Pacific is evidence of high levels of gene flow throughout this region. However, gene flow among widely separated reef complexes (average number of migrants per generation, N/em, approximately 2) is an order of magnitude less than that occurring within highly connected reef systems like the Ryukyus and the Great Barrier Reef (GBR) (Nem approximately 20). The genetic similarity between North-west Pacific and Australian populations is likely to reflect gene flow to each place from the central Indo-West Pacific region. Populations peripheral to the species' main distribution show greater genetic differentiation, probably as a result of founder effect. Some, like the Hawaiian and western Australian populations, show reduced genetic diversity, implying colonization by a very small number of individuals or a recent severe bottleneck in population size. Western Australian populations appear to have been derived from eastern Australian populations in the Pacific rather than Indian Ocean sources. On the GBR, genetic differentiation is low among populations that are undergoing outbreaks but there is significant differentiation among populations that are not involved in outbreaks; this suggests that a single primary source is the origin of outbreaks on the GBR. The development of distinctive DNA markers may also allow the detailed tracking of dispersal routes of A. planci and of recruitment within reefs.

Regional population structuring and conservation units in the platypus (Ornithorhynchus anatinus)

2013 ◽  
Vol 61 (5) ◽  
pp. 378 ◽  
Author(s):  
Stephen H. Kolomyjec ◽  
Tom R. Grant ◽  
Christopher N. Johnson ◽  
David Blair
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Large Scale ◽  
Wide Distribution ◽  
Conservation Units ◽  
Genetic Structuring ◽  
The North ◽  
Contemporary Gene Flow ◽  
Ornithorhynchus Anatinus ◽  
Southern Island

The platypus (Ornithorhynchus anatinus) has a wide distribution in Australia, encompassing the southern island of Tasmania and a broad latitudinal range of the mainland from the temperate south to the tropical north. We used 12 microsatellite markers from 235 individuals sampled from 13 river systems to examine patterns of genetic differentiation and gene flow throughout the species’ range. Using a Bayesian approach we identified three large-scale groupings that correspond closely to geographically distinct regions of the species’ distribution: the tropical northern mainland, the subtropical and temperate southern mainland, and Tasmania. Six additional clusters were found within the regional groups, three in the northern, two in the southern mainland regions, and the last in Tasmania. These clusters coincided with major river drainages. Genetic differentiation was generally high, with pairwise Fst values ranging from 0.065 to 0.368 for regions and 0.037 to 0.479 for clusters. We found no evidence of contemporary gene flow among the three clusters in the north, but some migration may occur between the larger clusters in the south. Due to the high genetic structuring and lack of gene flow between these three regional populations of the platypus we recommend their treatment as evolutionarily significant units (ESUs) within the platypus species. We have also detailed several smaller management units (MUs) existing within our study area based on subregional clusters and geographically significant features.

Redescription and new records ofCeltodoryx ciocalyptoides(Demospongiae: Poecilosclerida)—a sponge invader in the north east Atlantic Ocean of Asian origin?

2011 ◽  
Vol 91 (2) ◽  
pp. 347-355 ◽  
Author(s):  
Daniela Henkel ◽  
Dorte Janussen
Keyword(s):  
Abundant Species ◽  
East Atlantic ◽  
West Pacific ◽  
North West ◽  
North East ◽  
The North ◽  
First Case ◽  
The Pacific ◽  
Inshore Waters ◽  
Taxonomic Studies

In 1996 a sponge was found in a well studied area in the Ria of Etel, Brittany, France, that had never been recorded there before. This sponge was later described as a new species and genus,Celtodoryx girardaeby Perezet al.(2006), who concluded that it is probably an invasive species. Over several yearsC. girardaewas found to occur successively in the Gulf of Morbihan, France, and Oosterschelde estuary, Netherlands. This sponge is characterized by an extensive spatial broading and therewith it rates today among the dominant benthic megafauna in the shallow waters of the Gulf of Morbihan and Dutch inshore waters. During our recent survey of the Chinese Yellow Sea sponge fauna, we found an abundant species with close morphological similarities toC. girardae. Further taxonomic studies have revealed that both the Chinese and European sponges are in fact conspecific withCornulum ciocalyptoidesdescribed by Burton (1935) from Posiet Bay, Sea of Japan and later recorded from other localities of the North West Pacific (e.g. Koltun, 1971; Sim & Byeon, 1989). In this paper we transfer the species of Burton fromCornulumtoCeltodoryxand consequently it becomes the senior synonym ofC. girardae. Furthermore, we conclude thatCeltodoryx ciocalyptoideswas introduced to the North East Atlantic from the North West Pacific with aquaculture of the Pacific oysterCrassostrea gigasas the probable vector. This is probably the first case recorded so far of a sponge species being transferred from one ocean to another by human activity.

scholarly journals Spatial genetic structure and asymmetrical gene flow within the Pacific walrus

2012 ◽  
Vol 93 (6) ◽  
pp. 1512-1524 ◽  
Author(s):  
Sarah A. Sonsthagen ◽  
Chadwick V. Jay ◽  
Anthony S. Fischbach ◽  
George K. Sage ◽  
Sandra L. Talbot
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Spatial Genetic Structure ◽  
Genetic Relationships ◽  
Breeding Population ◽  
Pacific Walrus ◽  
Breeding Populations ◽  
The Pacific

Abstract Pacific walruses (Odobenus rosmarus divergens) occupying shelf waters of Pacific Arctic seas migrate during spring and summer from 3 breeding areas in the Bering Sea to form sexually segregated nonbreeding aggregations. We assessed genetic relationships among 2 putative breeding populations and 6 nonbreeding aggregations. Analyses of mitochondrial DNA (mtDNA) control region sequence data suggest that males are distinct among breeding populations (ΦST = 0.051), and between the eastern Chukchi and other nonbreeding aggregations (ΦST = 0.336–0.449). Nonbreeding female aggregations were genetically distinct across marker types (microsatellite FST = 0.019; mtDNA ΦST = 0.313), as was eastern Chukchi and all other nonbreeding aggregations (microsatellite FST = 0.019–0.035; mtDNA ΦST = 0.386–0.389). Gene flow estimates are asymmetrical from St. Lawrence Island into the southeastern Bering breeding population for both sexes. Partitioning of haplotype frequencies among breeding populations suggests that individuals exhibit some degree of philopatry, although weak. High levels of genetic differentiation among eastern Chukchi and all other nonbreeding aggregations, but considerably lower genetic differentiation between breeding populations, suggest that at least 1 genetically distinct breeding population remained unsampled. Limited genetic structure at microsatellite loci between assayed breeding areas can emerge from several processes, including male-mediated gene flow, or population admixture following a decrease in census size (i.e., due to commercial harvest during 1880–1950s) and subsequent recovery. Nevertheless, high levels of genetic diversity in the Pacific walrus, which withstood prolonged decreases in census numbers with little impact on neutral genetic diversity, may reflect resiliency in the face of past environmental challenges.

scholarly journals Genetic differentiation in an endangered and strongly philopatric, migrant shorebird

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nelli Rönkä ◽  
Veli-Matti Pakanen ◽  
Angela Pauliny ◽  
Robert L. Thomson ◽  
Kimmo Nuotio ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Environmental Changes ◽  
Isolation By Distance ◽  
Population Subdivision ◽  
Genetic Structuring ◽  
Long Distance ◽  
Mobile Species ◽  
High Dispersal ◽  
The Baltic

Abstract Background Populations living in fragmented habitats may suffer from loss of genetic variation and reduced between-patch dispersal, which are processes that can result in genetic differentiation. This occurs frequently in species with reduced mobility, whereas genetic differentiation is less common among mobile species such as migratory birds. The high dispersal capacity in the latter species usually allows for gene flow even in fragmented landscapes. However, strongly philopatric behaviour can reinforce relative isolation and the degree of genetic differentiation. The Southern Dunlin (Calidris alpina schinzii) is a philopatric, long-distance migratory shorebird and shows reduced dispersal between isolated breeding patches. The endangered population of the Southern Dunlin breeding at the Baltic Sea has suffered from habitat deterioration and fragmentation of coastal meadows. We sampled DNA across the entire population and used 12 polymorphic microsatellite loci to examine whether the environmental changes have resulted in genetic structuring and loss of variation. Results We found a pattern of isolation-by-distance across the whole Baltic population and genetic differentiation between local populations, even within the southern Baltic. Observed heterozygosity was lower than expected throughout the range and internal relatedness values were positive indicating inbreeding. Conclusions Our results provide long-term, empirical evidence for the theoretically expected links between habitat fragmentation, population subdivision, and gene flow. They also demonstrate a rare case of genetic differentiation between populations of a long-distance migratory species. The Baltic Southern Dunlin differs from many related shorebird species that show near panmixia, reflecting its philopatric life history and the reduced connectivity of its breeding patches. The results have important implications as they suggest that reduced connectivity of breeding habitats can threaten even long-distance migrants if they show strong philopatry during breeding. The Baltic Southern Dunlin warrants urgent conservation efforts that increase functional connectivity and gene flow between breeding areas.

scholarly journals Genetic Diversity and Population Structure of Medemia argun (Mart.) Wurttenb. ex H.Wendl. Based on Genome-Wide Markers

2021 ◽  
Vol 9 ◽  
Author(s):  
Sakina Elshibli ◽  
Helena Korpelainen
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Conservation Status ◽  
Ex Situ ◽  
Conservation Strategies ◽  
Nucleotide Polymorphisms ◽  
Genetic Structuring ◽  
Ancestral Gene ◽  
Low Genetic Diversity

Medemia argun is a wild, dioecious palm, adapted to the harsh arid environment of the Nubian Desert in Sudan and southern Egypt. There is a concern about its conservation status, since little is known about its distribution, abundance, and genetic variation. M. argun grows on the floodplains of seasonal rivers (wadis). The continuing loss of suitable habitats in the Nubian Desert is threatening the survival of this species. We analyzed the genetic diversity, population genetic structure, and occurrence of M. argun populations to foster the development of conservation strategies for M. argun. Genotyping-by-sequencing (GBS) analyses were performed using a whole-genome profiling service. We found an overall low genetic diversity and moderate genetic structuring based on 40 single-nucleotide polymorphisms (SNPs) and 9,866 SilicoDArT markers. The expected heterozygosity of the total population (HT) equaled 0.036 and 0.127, and genetic differentiation among populations/groups (FST) was 0.052 and 0.092, based on SNP and SilicoDArT markers, respectively. Bayesian clustering analyses defined five genetic clusters that did not display any ancestral gene flow among each other. Based on SilicoDArT markers, the results of the analysis of molecular variance (AMOVA) confirmed the previously observed genetic differentiation among generation groups (23%; p < 0.01). Pairwise FST values indicated a genetic gap between old and young individuals. The observed low genetic diversity and its loss among generation groups, even under the detected high gene flow, show genetically vulnerable M. argun populations in the Nubian Desert in Sudan. To enrich and maintain genetic variability in these populations, conservation plans are required, including collection of seed material from genetically diverse populations and development of ex situ gene banks.

scholarly journals Out of the Pacific: A New Alvinellid Worm (Annelida: Terebellida) From the Northern Indian Ocean Hydrothermal Vents

2021 ◽  
Vol 8 ◽  
Author(s):  
Yuru Han ◽  
Dongsheng Zhang ◽  
Chunsheng Wang ◽  
Yadong Zhou
Keyword(s):  
Indian Ocean ◽  
Hydrothermal Vents ◽  
Southwest Indian Ridge ◽  
Rrna Genes ◽  
Northwest Pacific ◽  
Northern Indian Ocean ◽  
West Pacific ◽  
The Pacific ◽  
The Indian Ocean ◽  
Indian Ridge

Alvinellids have long been considered to be endemic to Pacific vents until recent discovery of their presence in the Indian Ocean. Here, a new alvinellid is characterized and formally named from recently discovered vents, Wocan, and Daxi, in the northern Indian Ocean. Both morphological and molecular evidences support its placement in the genus Paralvinella, representing the first characterized alvinellid species out of the Pacific. The new species, formally described as Paralvinella mira n. sp. herein, is morphologically most similar to Paralvinella hessleri from the northwest Pacific, but the two species differ in three aspects: (1), the first three chaetigers are not fused in P. mira n. sp., whereas fused in P. hessleri; (2), paired buccal tentacles short and pointed in P. mira but large and strongly pointed in P. hessleri; (3), numerous slender oral tentacles ungrouped in P. mira but two groups in P. hessleri. Phylogenetic inference using the concatenated alignments of the cytochrome c oxidase I (COI), 16S rRNA and 18S rRNA genes strongly supports the clustering of P. mira with two West Pacific congeners, P. hessleri and an undescribed species (Paralvinella sp. ZMBN). The resulting Indian/West Pacific lineage suggests a possible invasion into the Indian Ocean from the West Pacific. This is the third polychaete reported from Wocan hydrothermal field. Among the three species, two including P. mira and Hesiolyra heteropoda (Annelida:Hesionidae) are present in high abundance, forming an alvinellids/hesionids-dominated polychaete assemblage distinct from that at all other Central Indian Ridge and Southwest Indian Ridge vents. Thus, this study expands our understanding of alvinellid biogeography beyond the Pacific, and adds to the unique biodiversity of the northern Indian Ocean vents, with implications for biogeographic subdivision across the Indian Ocean ridges.

scholarly journals The Cumacean (Crustacea: Peracarida) Genus Petalosarsia (Pseudocumatidae) from the Pacific Ocean

Zootaxa ◽  
2012 ◽  
Vol 3320 (1) ◽  
pp. 1 ◽  
Author(s):  
TADASHI AKIYAMA ◽  
SARAH GERKEN
Keyword(s):  
Ventral Surface ◽  
Wide Distribution ◽  
Caspian Region ◽  
West Pacific ◽  
North West ◽  
Sulu Sea ◽  
Tethys Sea ◽  
The North ◽  
The Pacific ◽  
Tasman Sea

The distribution of the cumacean family Pseudocumatidae is restricted to the North Atlantic, Mediterranean and brackishwaters of the Pont-Caspian region, except for three known species of the genus Petalosarsia. The present study describes ninespecies of Petalosarsia from Japanese waters, the Sulu Sea, the North-west Pacific, the Indo-West Pacific, and the Tasman Sea,Australia. The occurrence of P. declivis (Sars, 1865) in northern Hokkaido agrees with the reported circumpolar distribution ofthis species. Four species from the Pacific coast of southern Japan and the East China Sea, P. brevirostris Gamô 1986, P. ovalissp. nov., P. ryukyuensis sp. nov. and P. gamoi sp. nov., are characterized by prominent dorsolateral carinae with teeth anteriorlyand the basis of the 2nd maxilliped with a semicircular plate on the ventral surface. Nine specimens collected from the Sulu Seaincluded five species, P. brevirostris, P. gamoi, P. jonesi sp. nov. P. suluensis sp. nov. and P. longicauda sp. nov. The latterthree species were characterized by no or faint dorsolateral carinae on the carapace. Among them, P. jonesi was similar to P.longirostris from the eastern tropical deep Atlantic. Petalosarsia australis sp. nov. from the Tasman Sea is characterized by onefaint pair of dorsolateral carinae running for the entire length of the carapace. The species richness of Petalosarsia in the SuluSea and the Indo-West Pacific suggests a wide distribution of ancestors of Pseudocumatidae around the ancient Tethys Sea, with the Ponto-Caspian region located near the center. The habitat of Petalosarsia was mostly deeper than 200 m.

scholarly journals Analysis of genome-wide differentiation between native and introduced populations of the cupped oysters Crassostrea gigas and Crassostrea angulata

2018 ◽  
Author(s):  
Pierre-Alexandre Gagnaire ◽  
Jean-Baptiste Lamy ◽  
Florence Cornette ◽  
Serge Heurtebise ◽  
Lionel Dégremont ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Crassostrea Gigas ◽  
The North ◽  
Introduced Populations ◽  
Genome Wide ◽  
Crassostrea Angulata ◽  
The Pacific ◽  
Demographic Inference ◽  
Native And Introduced Ranges

AbstractThe Pacific cupped oyster is genetically subdivided into two sister taxa, Crassostrea gigas and C. angulata, which are in contact in the north-western Pacific. The nature and origin of their genetic and taxonomic differentiation remains controversial due the lack of known reproductive barriers and morphologic similarity. In particular, whether ecological and/or intrinsic isolating mechanisms participate to species divergence remains unknown. The recent co-introduction of both taxa into Europe offers a unique opportunity to test how genetic differentiation maintains under new environmental and demographic conditions. We generated a pseudo-chromosome assembly of the Pacific oyster genome using a combination of BAC-end sequencing and scaffold anchoring to a new high-density linkage map. We characterized genome-wide differentiation between C. angulata and C. gigas in both their native and introduced ranges, and showed that gene flow between species has been facilitated by their recent co-introductions in Europe. Nevertheless, patterns of genomic divergence between species remain highly similar in Asia and Europe, suggesting that the environmental transition caused by the co-introduction of the two species did not affect the genomic architecture of their partial reproductive isolation. Increased genetic differentiation was preferentially found in regions of low recombination. Using historical demographic inference, we show that the heterogeneity of differentiation across the genome is well explained by a scenario whereby recent gene flow has eroded past differentiation at different rates across the genome after a period of geographical isolation. Our results thus support the view that low-recombining regions help in maintaining intrinsic genetic differences between the two species.

scholarly journals Genetic differentiation in two European tree frog (Hyla arborea) metapopulations in contrasted landscapes of western Switzerland

2009 ◽  
Vol 30 (1) ◽  
pp. 127-133 ◽  
Author(s):  
Sylvain Dubey ◽  
Luca Fumagalli ◽  
Sylvain Ursenbacher ◽  
Jérôme Pellet
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Tree Frog ◽  
Genetic Structuring ◽  
Hyla Arborea ◽  
Heterogeneous Landscape ◽  
Loss Of Genetic Diversity ◽  
Suitable Habitats ◽  
Two Sectors

AbstractThe survival of threatened species as the European tree frog (Hyla arborea) is strongly dependent on the genetic variability within populations, as well as gene flow between them. In Switzerland, only two sectors in its western part still harbour metapopulations. The first is characterised by a very heterogeneous and urbanized landscape, while the second is characterised by a uninterrupted array of suitable habitats. In this study, six microsatellite loci were used to establish levels of genetic differentiation among the populations from the two different locations. The results show that the metapopulations have: (i) weak levels of genetic differentiation (FST within metapopulation ≈ 0.04), (ii) no difference in levels of genetic structuring between them, (iii) significant (p = 0.019) differences in terms of genetic diversity (Hs) and observed heterozygozity (Ho), the metapopulation located in a disturbed landscape showing lower values. Our results suggest that even if the dispersal of H. arborea among contiguous ponds seems to be efficient in areas of heterogeneous landscape, a loss of genetic diversity can occur.

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