Presentation on theme: "Molecular-genetic analysis of starfishes Asterias amurensis and A. rubens A.L. Drozdov, I.P. Vladychenskaya,, N.B. Petrov red seastar A. rubens, red seastar."— Presentation transcript:
Molecular-genetic analysis of starfishes Asterias amurensis and A. rubens A.L. Drozdov, I.P. Vladychenskaya,, N.B. Petrov red seastar A. rubens, red seastar A. rubens, common, or Forbes starfish A. forbesi Institute of Marine Biology, FEB RAS, Moscow State Un iversity Asterias amurensis the Northern Pacific seastar and Japanese common starfish
Now A. amurensis has been introduced to the oceanic areas of Tasmania, southern Australia, Alaska, the Aleutian Island, part of Europe and Maine.
A.forbesi (Desor,1848 )(North Atlantic Ocean from the Gulf of Maine to the Gulf of Mexico ) A. rubens A.amurensis Lutken, 1871 ( norther China,China Russia,,Japan. )RussiaJapan Linnaeus, 1758 ( nother Atlantic, common species in North & White seas, west part of Baltic sea )
In this study we analyzed the mitochondria COI genes in A. rubens and A. amurensis. The obtained sequences were aligned with homologous sequences of other species of the North Atlantic and Pacific sea stars, taken from Genbank (www.ncbi.nlm.nih.gov), and held their phylogenetic analysis using the software package MEGA 5.
Phylogene- tic tree of fragment sequences of mitochond- rial COI gene in several species of sea stars.
Phylogenetic trees for Asterias generated using the best-fit maximum likelihood model in each data set (COI: HKY + f ; ITS: F81). (A) Cytochrome c oxidase I phylogeny of inter- and intraspecific Asterias relationships. Here all characters (first, second, and third position) are included; an identical topology is found using parsimony or distance methods, or looking at third-position characters alone. Bootstrap support for each species is indicated by the numbers below each branch. These data do not reject a molecular clock model. The divergence across the Arctic (between A. amurensis and the Atlantic species) is considered to be 3.5 Ma; this generates an estimate of about 3.0 Ma for the divergence between A. rubens and A. amurensis. Biogeography of Asterias: North Atlantic Climate Change and Speciation (after Wares, 2001
The ratio of species of sea stars in common with the North Atlantic and North Pacific in a variety of Arctic regions at depths of m. 1 - the proportion of species (%) in common with the North Atlantic, and 2 - the proportion of species (%) in common with the North Pacific.
The ratio of starfish species with the North Atlantic and North Pacific origin in a variety Arctic regions at depths of m. 1 - the proportion of species (%) from the North Atlantic, 2 - the proportion of species (%) in common with the North Pacific, 3 - species of unknown origin
The proportion of different origins species in the individual basins of the Arctic Ocean. NorS - Norwegian Sea; BarS - Barents Sea; KarS - Kara Sea; LapS - Laptev Sea; ESibS - East Siberian Sea; ChukS - Chukchi Sea; NLGB - Norwegian and Greenland basins; CAB - Nansen and Amundsen; CanB - Canadian Basin. (Krylova, Ivanov, 2012)
The evolutionary relationships between taxa of sea stars, derived by the maximum parsimony method from mitochondrial COI gene sequences.
The results of the analysis indicate a high degree of interspecies isolation studied in this paper types. The level of intraspecific divergence estimated from genetic distances within species clusters varied in the range between and 0.009, while the level of interspecific divergence, as measured by genetic distance between species clusters, varied in the range between and In comparisons with mitochondrial COI marker, evaluation of genetic divergence from nuclear gene markers (ITS 1 and 2, 5.8S rRNA gene) revealed lower level of interspecies divergence, but higher level intergeneric divergence. Analysis of the current geographical distribution of the genus Asterias points to inhabit two species in the North Atlantic. A. forbesii dwells on the shelf of the North American coast from Cape Hatteras to Cape Cape Cod, north of the area which extends A. rubens. European populations which inhabit the shelf of the European Atlantic coast of Iceland to the west of France. The U.S. population A. rubens originally were referred to the species A. vulgaris. Areas of North American populations of A. forbesi and A. rubens overlap to a large part of the shelf around Cape Cape Cod (Franz et al., 1981). Large genetic distances between populations of these species indicate a lack of cross-species hybridization.
Paleontological data show that the penetration of the genus Asterias in the North Atlantic there were at least 3.5 million years ago, followed by trans-Arctic migration was interrupted due to climate change (Worley, Franz, 1983). This date is the starting point for determining the time of divergence between the North Pacific and North Atlantic sea A.amurensis taxa (Wares, 2001). Our results show that the genetic distance between the North Atlantic taxa is no less than between A.amurensis and North Atlantic taxa. Consequently, the exchange of genes between the North Atlantic populations of A. forbesi and A. rubens, too, had to be interrupted not later than 3.5 million years ago.
Molecular-genetic analysis of starfishes Asterias amurensis and A. rubens A.L. Drozdov, I.P. Vladychenskaya,, N.B. Petrov Institute of Marine Biology, FEB RAS, Moscow State Un iversity Asterias amurensis, red sea star A. rubens, common, or Forbes sea star A. forbesi