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Anemonas reproduccion asexual


In this paper we use allozyme analyses to demonstrate that individuals in Anthopleura krebsi aggregates are monoclonal.

Additionally, sympatric samples of the red and the green colour-morphs of A. All individuals within aggregates of the green colour-morph were found to be identical over the Anemonas reproduccion asexual polymorphic loci analysed. Cnidaria, allozymes, clones, fission, molecular systematics. Sea anemones are polyp animals of Actiniaria, an order of skeletonless Anthozoa.

Longitudinal fission has traditionally been acknowledged as the most common type of asexual reproduction in sea anemones of the family Actiniidae Shick This type of reproduction has important ecological consequences, since it often leads to the production of geographically restricted clones, which can out-compete exclusively sexually reproducing species Jackson Other three species of this genus have been inferred to reproduce asexually based upon their aggregation habit and the irregularity of some characters like number of mesenteries and siphonoglyphs.

The best approach for the confirmation of the presence of asexual reproduction in natural Anemonas reproduccion asexual is the study of composite genotypes using genetic markers JacksonAvise Genetic markers Anemonas reproduccion asexual been used successfully to determine the asexual origin of broods of several species of sea anemones Gashout and OrmondCarter and ThorpSchaeferMonteiro et a l.

The rationale behind the usage of molecular markers to study asexual reproduction is that it is extremely unlikely that two sexually produced individuals will be identical over a large number of polymorphic loci.

The two types occur sympatrically on the same position in the intertidal area. Bigger studied the aggressive behaviour of A. No aggression was observed between individuals from the same putative clone, neither between individuals supposedly from different clones of the "red" colour-morph.

The constant antagonism between the anemones of the two colour-morphs, compared to the small aggression between clones Anemonas reproduccion asexual the red morph or some of the clones of the green morph, could be an indication that all anemones of the red morph Anemonas reproduccion asexual members of one single clone, whereas the green anemones belonged to different clones, or that, instead of being between individuals of the same species, the aggression was interspecific like that observed between the clonal and solitary forms of A.

In this case, the two colour-morphs should be raised to specific status. The aims of this paper were, thus, to verify whether individuals in A. Materials and methods a Collection of samples: Care was taken to collect individuals Anemonas reproduccion asexual were at least 2 meters apart as in Monteiro et al.

The anemones were usually found in horizontal crevices on the upper area of the intertidal zone on the shore side of a beach rock sensu Guilcher These individuals would normally be inferred to be "clone-mates", based on their proximity and their homogeneity in colour and size. All anemones were transported alive in seawater and maintained in an aquarium until electrophoresis, which occurred no later than one week after collection.

Samples were ground with a glass rod in a cold solution 1: Stains for seventeen enzymes were tested, of which thirteen yielded reproducible results Table 2.

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The electrophoretic work was divided into two phases: Second, the genotypes of the putative clone-mates were determined for the more polymorphic enzymes, to verify whether they indeed belonged to monoclonal colonies. For that, we used the composite probability of complete identity over all polymorphic loci analysed, using the gene frequencies of the green morph estimated in the first part of the work as in Monteiro et al. Results Comparison between colour morphs: Gene frequencies of the two colour morphs of Anthopleura Anemonas reproduccion asexual studied are given in Table 3.

A pair-wise comparison of the genotypes of the anemones of each colour morph demonstrated that each anemone collected within each colour morph was genetically unique. Comparison between putative clone-mates: The genotypes of the individuals within each of the two putative clones analysed were identical over the five polymorphic loci analysed Clone 1: Discussion The main results of this work were the genetic demonstration of asexual reproduction in Anthopleura krebsi and the high genetic similarity between its green and red colour morphs.

The genetic study of the two groups of individuals supposed to be clones, demonstrates that they originated through asexual reproduction. Given the high level of gene variation observed "Anemonas reproduccion asexual" A.

The complete genotype identity of the anemones within each clone, thus, clearly shows that they are clone-mates.

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Populations of sea anemones that have facultative asexual reproduction are usually found, in the intertidal zone, to consist of locally distributed clones e. The population of A. The two clones studied were genetically distinct, regardless of the relatively short distance 2m between them.

Since, during the fieldwork, care was taken to avoid collecting samples closer than 2 meters from each other, it can be said that clones in this species are unlikely to be spread "Anemonas reproduccion asexual" areas larger than 2 meters, at least in the region studied.

Therefore, it appears that A. Sympatric samples of different morphs should, if conspecific, be freely interbreeding. This means that, within sampling errors, they should have the same gene frequencies at each gene locus. They should be different only at the loci coding for the morphological difference used to separate them in the first place, and perhaps some closely linked loci.

Usually, conspecific populations of marine invertebrates Anemonas reproduccion asexual gene identity values above 0. The sympatric populations of the red and green morphs of A.

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This result and the absence of diagnostic loci, indicates that there is no restriction to gene flow between the two colour morphs of A. Colour has been considered a unreliable character for sea anemone taxonomy Stephenson However, in many cases it has proven to be a good first evidence of interspecific differences: Contrastingly, no genetic differences were observed McFadden et al.

Also, colour morphs of Adamsia carcioniopados "pink" and "white" mesenteric filamentsof Anemonia viridis "green" and "red" columns and of Metridium senile "brown" and "white" columns from Britain A. Russo, unpublished results did not display any major genetic differences. There appears to be a strong bias in the literature for molecular systematics papers describing the detection of genetic isolation between colour morphs, in detriment of those indicating that they were conspecific.

Molecular systematics has, indeed, demonstrated that, many times, Anemonas reproduccion asexual variation treated by taxonomists as phenotypic plasticity or intraspecific polymorphism was in fact due to interspecific differences reviewed in Knowlton However, because of the publication bias in the field, this trend has been exaggerated, to a point that some may prematurely conclude that most of the described colour morphs in marine invertebrates do belong to different species.

We believe that the best way to obtain a more balanced view of this Anemonas reproduccion asexual will be through the publication not only of molecular systematics papers demonstrating hidden species, but also of those presenting genetic evidence of conspecificity between colour morphs.

Transcript of LAS ANÉMONAS O...

Anemonas reproduccion asexual Markers, Natural History and Evolution. Enzymes as taxonomic characters. Adaptive and Taxonomic Significance. The effects of asexual reproduction and intergenotypic aggression on the genotypic structure of populations of the sea anemone Actinia tenebros a. Systematic position and morphological and microanatomical revision. Morphological and microanatomical study of Anthopleura krebsi Duchassaing and Michelotti, Cnidaria, Anthozoa, Actiniidaea new record in Brazil.

Interspecific and intraspecific acrorhagial aggressive behavior among sea anemones: Asexual reproduction and genetic determination of colour patterns within populations of the subtidal sea anemone Anthothoe albocinct a.

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