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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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Principal Coordinate Analysis of microsatellite data.The first two principal coordinate axes are shown that represent 24% and 14% of the variation. K-means groups are represented with polygons surrounding isolates from Pyr lakes (green triangles) and ponds (green squares), from HTM (red circles), and from LLaP (blue diamonds).
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pone-0020049-g002: Principal Coordinate Analysis of microsatellite data.The first two principal coordinate axes are shown that represent 24% and 14% of the variation. K-means groups are represented with polygons surrounding isolates from Pyr lakes (green triangles) and ponds (green squares), from HTM (red circles), and from LLaP (blue diamonds).

Mentions: Principal Coordinate Analysis (PCoA) revealed relatively good separation of populations from the geographic regions with the first two axes accounting for 24% and 14% of the variation (Figure 2). The calinski criterion obtained with CascadeKM indicated that three groups best represented our data. The first group included isolates from Pyr lakes, the second group included isolates from LLaP, and the third group included isolates from HTM, Pyr ponds and lakes, and LLaP. HTM isolates were intermediate those from Pyr lakes and LLaP. Furthermore, these results showed the presence of admixture between isolates from Pyr lakes and Pyr ponds (Figure 2).


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)

Principal Coordinate Analysis of microsatellite data.The first two principal coordinate axes are shown that represent 24% and 14% of the variation. K-means groups are represented with polygons surrounding isolates from Pyr lakes (green triangles) and ponds (green squares), from HTM (red circles), and from LLaP (blue diamonds).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0020049-g002: Principal Coordinate Analysis of microsatellite data.The first two principal coordinate axes are shown that represent 24% and 14% of the variation. K-means groups are represented with polygons surrounding isolates from Pyr lakes (green triangles) and ponds (green squares), from HTM (red circles), and from LLaP (blue diamonds).
Mentions: Principal Coordinate Analysis (PCoA) revealed relatively good separation of populations from the geographic regions with the first two axes accounting for 24% and 14% of the variation (Figure 2). The calinski criterion obtained with CascadeKM indicated that three groups best represented our data. The first group included isolates from Pyr lakes, the second group included isolates from LLaP, and the third group included isolates from HTM, Pyr ponds and lakes, and LLaP. HTM isolates were intermediate those from Pyr lakes and LLaP. Furthermore, these results showed the presence of admixture between isolates from Pyr lakes and Pyr ponds (Figure 2).

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