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Diversity in the reproductive modes of European Daphnia pulicaria deviates from the geographical parthenogenesis.

Dufresne F, Marková S, Vergilino R, Ventura M, Kotlík P - PLoS ONE (2011)

Bottom Line: These newly formed asexual lineages are differentially distributed being found predominantly at high latitudes.Inferred transitions to obligate parthenogenesis have occurred only in HTM, most likely as a result of hybridizations.In contrast to North American populations, these transitions do not appear to involve meiosis suppressor genes and have not been accompanied by polyploidy.

View Article: PubMed Central - PubMed

Affiliation: Département de Biologie, Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, Québec, Canada. france_dufresne@uqar.qc.ca

ABSTRACT

Background: Multiple transitions to obligate parthenogenesis have occurred in the Daphnia pulex complex in North America. These newly formed asexual lineages are differentially distributed being found predominantly at high latitudes. This conforms to the rule of geographical parthenogenesis postulating prevalence of asexuals at high latitudes and altitudes. While the reproductive mode of high-latitude populations is relatively well studied, little is known about the reproduction mode in high altitudes. This study aimed to assess the reproductive mode of Daphnia pulicaria, a species of the D. pulex complex, from high altitude lakes in Europe.

Methodology/principal findings: Variation at eight microsatellite loci revealed that D. pulicaria from the High Tatra Mountains (HTM) had low genotype richness and showed excess of heterozygotes and significant deviations from Hardy-Weinberg expectations, and was thus congruent with reproduction by obligate parthenogenesis. By contrast, populations from the Pyrenees (Pyr) were generally in Hardy-Weinberg equilibrium and had higher genotypic richness, suggesting that they are cyclic parthenogens. Four lakes from lowland areas (LLaP) had populations with an uncertain or mixed breeding mode. All D. pulicaria had mtDNA ND5 haplotypes of the European D. pulicaria lineage. Pyr were distinct from LLaP and HTM at the ND5 gene. By contrast, HTM shared two haplotypes with LLaP and one with Pyr. Principal Coordinate Analysis of the microsatellite data revealed clear genetic differentiation into three groups. HTM isolates were intermediate to Pyr and LLaP, congruent with a hybrid origin.

Conclusion/significance: Inferred transitions to obligate parthenogenesis have occurred only in HTM, most likely as a result of hybridizations. In contrast to North American populations, these transitions do not appear to involve meiosis suppressor genes and have not been accompanied by polyploidy. The absence of obligate parthenogenesis in Pyr, an environment highly similar to the HTM, may be due to the lack of opportunities for hybridization.

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Maximum likelihood phylogeny of mtDNA haplotypes.Statistical support for the major clades is expressed as the percentage bootstrap proportions of 1000 replicates and as the SH-like approximate likelihood ratio probabilities.
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pone-0020049-g003: Maximum likelihood phylogeny of mtDNA haplotypes.Statistical support for the major clades is expressed as the percentage bootstrap proportions of 1000 replicates and as the SH-like approximate likelihood ratio probabilities.

Mentions: Combining new ND5 data with sequences from [11] resulted in a dataset containing 120 polymorphic sites, 100 of which were phylogenetically informative. Maximum-likelihood phylogenetic analysis of this data set resulted in a well-resolved tree (-Ln likelihood  =  2030.665; Figure 3), placing the all haplotypes from the three different regions in Europe (HTM, Pyr and LLaP) into the European D. pulicaria lineage (EuroPC), consistent with the RFLP analysis. Most of the haplotypes from Pyr cluster together and form a clade inside the EuroPC lineage. However, two Pyr sequences were identical with a HTM sequence (DP14_01 haplotype in Figure 3). HTM haplotypes were dispersed within LLaP haplotypes and, in addition, haplotypes DP01_19 and DP03_7 were shared with Lake Ohrid and with Lake Chabařovice and pond Nový, respectively, which suggested postglacial colonization of HTM and LLaP from the same source. Haplotypes of the obligate and cyclic parthenogens (see below) were interspersed in the phylogeny, and some haplotypes were found in obligate as well as cyclic populations (Figure 4).


Diversity in the reproductive modes of European Daphnia pulicaria deviates from the geographical parthenogenesis.

Dufresne F, Marková S, Vergilino R, Ventura M, Kotlík P - PLoS ONE (2011)

Maximum likelihood phylogeny of mtDNA haplotypes.Statistical support for the major clades is expressed as the percentage bootstrap proportions of 1000 replicates and as the SH-like approximate likelihood ratio probabilities.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3104988&req=5

pone-0020049-g003: Maximum likelihood phylogeny of mtDNA haplotypes.Statistical support for the major clades is expressed as the percentage bootstrap proportions of 1000 replicates and as the SH-like approximate likelihood ratio probabilities.
Mentions: Combining new ND5 data with sequences from [11] resulted in a dataset containing 120 polymorphic sites, 100 of which were phylogenetically informative. Maximum-likelihood phylogenetic analysis of this data set resulted in a well-resolved tree (-Ln likelihood  =  2030.665; Figure 3), placing the all haplotypes from the three different regions in Europe (HTM, Pyr and LLaP) into the European D. pulicaria lineage (EuroPC), consistent with the RFLP analysis. Most of the haplotypes from Pyr cluster together and form a clade inside the EuroPC lineage. However, two Pyr sequences were identical with a HTM sequence (DP14_01 haplotype in Figure 3). HTM haplotypes were dispersed within LLaP haplotypes and, in addition, haplotypes DP01_19 and DP03_7 were shared with Lake Ohrid and with Lake Chabařovice and pond Nový, respectively, which suggested postglacial colonization of HTM and LLaP from the same source. Haplotypes of the obligate and cyclic parthenogens (see below) were interspersed in the phylogeny, and some haplotypes were found in obligate as well as cyclic populations (Figure 4).

Bottom Line: These newly formed asexual lineages are differentially distributed being found predominantly at high latitudes.Inferred transitions to obligate parthenogenesis have occurred only in HTM, most likely as a result of hybridizations.In contrast to North American populations, these transitions do not appear to involve meiosis suppressor genes and have not been accompanied by polyploidy.

View Article: PubMed Central - PubMed

Affiliation: Département de Biologie, Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, Québec, Canada. france_dufresne@uqar.qc.ca

ABSTRACT

Background: Multiple transitions to obligate parthenogenesis have occurred in the Daphnia pulex complex in North America. These newly formed asexual lineages are differentially distributed being found predominantly at high latitudes. This conforms to the rule of geographical parthenogenesis postulating prevalence of asexuals at high latitudes and altitudes. While the reproductive mode of high-latitude populations is relatively well studied, little is known about the reproduction mode in high altitudes. This study aimed to assess the reproductive mode of Daphnia pulicaria, a species of the D. pulex complex, from high altitude lakes in Europe.

Methodology/principal findings: Variation at eight microsatellite loci revealed that D. pulicaria from the High Tatra Mountains (HTM) had low genotype richness and showed excess of heterozygotes and significant deviations from Hardy-Weinberg expectations, and was thus congruent with reproduction by obligate parthenogenesis. By contrast, populations from the Pyrenees (Pyr) were generally in Hardy-Weinberg equilibrium and had higher genotypic richness, suggesting that they are cyclic parthenogens. Four lakes from lowland areas (LLaP) had populations with an uncertain or mixed breeding mode. All D. pulicaria had mtDNA ND5 haplotypes of the European D. pulicaria lineage. Pyr were distinct from LLaP and HTM at the ND5 gene. By contrast, HTM shared two haplotypes with LLaP and one with Pyr. Principal Coordinate Analysis of the microsatellite data revealed clear genetic differentiation into three groups. HTM isolates were intermediate to Pyr and LLaP, congruent with a hybrid origin.

Conclusion/significance: Inferred transitions to obligate parthenogenesis have occurred only in HTM, most likely as a result of hybridizations. In contrast to North American populations, these transitions do not appear to involve meiosis suppressor genes and have not been accompanied by polyploidy. The absence of obligate parthenogenesis in Pyr, an environment highly similar to the HTM, may be due to the lack of opportunities for hybridization.

Show MeSH
Related in: MedlinePlus