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Genetic divergence and phylogeographic history of two closely related species (Leucomeris decora and Nouelia insignis) across the 'Tanaka Line' in Southwest China.

Zhao YJ, Gong X - BMC Evol. Biol. (2015)

Bottom Line: The study revealed comprehensive species divergence and phylogeographic histories of N. insignis and L. decora divided by the Tanaka Line.The phylogeographic pattern inferred from cpDNA reflected ancestrally shared polymorphisms without post-divergence gene flow between species.The marked genealogical lineage divergence in nDNA provided some indication of Tanaka Line for its role as a barrier to plant dispersal, and lent support to its importance in promoting strong population structure and allopatric divergence.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650204, China. zyy36920@126.com.

ABSTRACT

Background: Leucomeris decora and Nouelia insignis (Asteraceae) are narrowly and allopatrically distributed species, separated by the important biogeographic boundary Tanaka Line in Southwest China. Previous morphological, cytogenetic and molecular studies suggested that L. decora is sister to N. insignis. However, it is less clear how the two species diverged, whether in full isolation or occurring gene flow across the Tanaka Line. Here, we performed a molecular study at the population level to characterize genetic differentiation and decipher phylogeographic history in two closely related species based on variation examined in plastid and nuclear DNAs using a coalescent-based approach.

Results: These morphologically distinct species share plastid DNA (cpDNA) haplotypes. In contrast, Bayesian analysis of nuclear DNA (nDNA) uncovered two distinct clusters corresponding to L. decora and N. insignis. Based on the IMa analysis, no strong indication of migration was detected based on both cpDNA and nDNA sequences. The molecular data pointed to a major west-east split in nuclear DNA between the two species corresponding with the Tanaka Line. The coalescent time estimate for all cpDNA haplotypes dated to the Mid-Late Pleistocene. The estimated demographic parameters showed that the population size of L. decora was similar to that of N. insignis and both experienced limited demographic fluctuations recently.

Conclusions: The study revealed comprehensive species divergence and phylogeographic histories of N. insignis and L. decora divided by the Tanaka Line. The phylogeographic pattern inferred from cpDNA reflected ancestrally shared polymorphisms without post-divergence gene flow between species. The marked genealogical lineage divergence in nDNA provided some indication of Tanaka Line for its role as a barrier to plant dispersal, and lent support to its importance in promoting strong population structure and allopatric divergence.

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Mismatch distribution for cpDNA sequence data in Leucomeris decora(a, b) and Nouelia insignis(c, d), under the spatial expansion model (a, c) and demographic expansion mode (b, d), respectively. The line with hollow dot shows observed values, while the line with solid dot represents expected values under the model of spatial/demographic expansion
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Fig5: Mismatch distribution for cpDNA sequence data in Leucomeris decora(a, b) and Nouelia insignis(c, d), under the spatial expansion model (a, c) and demographic expansion mode (b, d), respectively. The line with hollow dot shows observed values, while the line with solid dot represents expected values under the model of spatial/demographic expansion

Mentions: Neither the Tajima’s D nor Fu’s Fs neutrality tests yielded significantly negative results for all L. decora populations or N. insignis populations (Table 3). Similarly, the mismatch distribution was multimodal for L. decora populations with uniformly significant SSD and HRag values. However, the unimodal distribution pattern with non-significant SSD and HRag values was presented by all N. insignis populations under the demographic expansion model (Fig. 5). All these observations indicate the absence of expansion events.Table 3


Genetic divergence and phylogeographic history of two closely related species (Leucomeris decora and Nouelia insignis) across the 'Tanaka Line' in Southwest China.

Zhao YJ, Gong X - BMC Evol. Biol. (2015)

Mismatch distribution for cpDNA sequence data in Leucomeris decora(a, b) and Nouelia insignis(c, d), under the spatial expansion model (a, c) and demographic expansion mode (b, d), respectively. The line with hollow dot shows observed values, while the line with solid dot represents expected values under the model of spatial/demographic expansion
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4495643&req=5

Fig5: Mismatch distribution for cpDNA sequence data in Leucomeris decora(a, b) and Nouelia insignis(c, d), under the spatial expansion model (a, c) and demographic expansion mode (b, d), respectively. The line with hollow dot shows observed values, while the line with solid dot represents expected values under the model of spatial/demographic expansion
Mentions: Neither the Tajima’s D nor Fu’s Fs neutrality tests yielded significantly negative results for all L. decora populations or N. insignis populations (Table 3). Similarly, the mismatch distribution was multimodal for L. decora populations with uniformly significant SSD and HRag values. However, the unimodal distribution pattern with non-significant SSD and HRag values was presented by all N. insignis populations under the demographic expansion model (Fig. 5). All these observations indicate the absence of expansion events.Table 3

Bottom Line: The study revealed comprehensive species divergence and phylogeographic histories of N. insignis and L. decora divided by the Tanaka Line.The phylogeographic pattern inferred from cpDNA reflected ancestrally shared polymorphisms without post-divergence gene flow between species.The marked genealogical lineage divergence in nDNA provided some indication of Tanaka Line for its role as a barrier to plant dispersal, and lent support to its importance in promoting strong population structure and allopatric divergence.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650204, China. zyy36920@126.com.

ABSTRACT

Background: Leucomeris decora and Nouelia insignis (Asteraceae) are narrowly and allopatrically distributed species, separated by the important biogeographic boundary Tanaka Line in Southwest China. Previous morphological, cytogenetic and molecular studies suggested that L. decora is sister to N. insignis. However, it is less clear how the two species diverged, whether in full isolation or occurring gene flow across the Tanaka Line. Here, we performed a molecular study at the population level to characterize genetic differentiation and decipher phylogeographic history in two closely related species based on variation examined in plastid and nuclear DNAs using a coalescent-based approach.

Results: These morphologically distinct species share plastid DNA (cpDNA) haplotypes. In contrast, Bayesian analysis of nuclear DNA (nDNA) uncovered two distinct clusters corresponding to L. decora and N. insignis. Based on the IMa analysis, no strong indication of migration was detected based on both cpDNA and nDNA sequences. The molecular data pointed to a major west-east split in nuclear DNA between the two species corresponding with the Tanaka Line. The coalescent time estimate for all cpDNA haplotypes dated to the Mid-Late Pleistocene. The estimated demographic parameters showed that the population size of L. decora was similar to that of N. insignis and both experienced limited demographic fluctuations recently.

Conclusions: The study revealed comprehensive species divergence and phylogeographic histories of N. insignis and L. decora divided by the Tanaka Line. The phylogeographic pattern inferred from cpDNA reflected ancestrally shared polymorphisms without post-divergence gene flow between species. The marked genealogical lineage divergence in nDNA provided some indication of Tanaka Line for its role as a barrier to plant dispersal, and lent support to its importance in promoting strong population structure and allopatric divergence.

Show MeSH
Related in: MedlinePlus