Genetic Structure of Sympatric Sexually and Parthenogenetically Reproducing Population ofChara canescens(Charophyta)

Abstract

Individuals that reproduce parthenogenetically do not have to produce males and can therefore produce twice as many female offspring. With this twofold reproduction advantage of asexual reproduction, the question of how sex persists in the short term remains unresolved. In the dioecious charophyte Chara canescens, both parthenogenetically reproducing females and sexually reproducing females and males occur sympatrically at only one site in Europe: Neusiedler See-Seewinkel (Austria). By means of four nuclear species-specific microsatellite loci, we examined the interaction between coexisting sexuals and parthenogens by analysing the population structure and gene flow between both reproduction systems. Using a Bayesian assignment method, we found that the sites encompassed two genetically distinct clusters of individuals. The first cluster included genotypes of sexual individuals, which are genetically distinct from a second cluster which included parthenogenetic individuals and few sexually reproducing males, which are genetically identical to the parthenogenetic individuals. However, an analysis of the population genetic structure found no differences with respect to genotypic variation, clonal diversity, and population differentiation between the sympatric parthenogenetically and the sexually reproducing populations. The results indicated that the parthenogenetic individuals cannot outcompete the sexually reproducing individuals.

Some Charophyta (Charales) from Coastal Temporary Ponds in Velipoja Area (North Albania)

“…4) recorded here as new to Albania was found to grow in all surveyed localities, but in localities 1 and 5 was more abundant. The species represents populations with only female plants, like in the northern parts of Europe and Mediterranean coast [19,26,27]. In the area, it covers ponds bottom at a depth of 0.1-0.2 m, forming a monospecific population or associated with Chara baltica and Chara aspera or Tolypella glomerata.…”

“…Chara canescens is common in the northern hemisphere and its occurrence is restricted to brackish waters [3,4,21,27,28]. In Europe, it is found scattered along the coasts and in south east of the continent, many localities have been lost [4,28].…”

Rediscovery of Chara canescens Loiseleur in Serbia

“…A very unique peculiarity of C. canescens within the genus Chara is the occurrence of parthenogenesis, which, moreover, is just an option to sexual reproduction (Krause 1997). However, bisexual populations are rare and most of the populations known in Europe consist of parthenogetic female individuals exclusively (Küster et al 2004;Schaible et al 2011). In a parthenogenetic population of C. canescens, asexual reproduction is obligatory and irreversible; specimens cannot reproduce vegetatively, but only by oospore germination.…”

“…Being an annual species, growth is fast and reproduction relies on semelparity for sexual as well as parthenogenetic individuals (Blindow & Schubert 2004;Schaible et al 2012). Extant bisexual populations are extremely rare and limited to a few localities in Europe -Austria (the border area between Austria and Hungary) and Spain (Cirujano et al 2008;Schaible & Schubert 2008;Schaible et al 2011). An extinct bisexual population is also well documented by herbarium material collected close to Montpellier in France (Corillion 1957(Corillion , 1975.…”

“…Considering the presence of several more waterbodies of the same origin as the Plava Banja pond near the city of Kikinda and many more in the wider area of the Vojvodina province, we emphasise that the distribution of C. canescens should be carefully investigated. Such mapping and monitoring should be conducted especially in order to check for the existence of sexually reproducing populations such as have been observed at sites with a comparable climatic background (Corillion 1957(Corillion , 1975Cirujano et al 2008;Schaible et al 2011). Possible confirmation of male specimens would make such a population one of very few in Europe (Schaible et al 2011).…”