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Flowering time diversification and dispersal in central Eurasian wild wheat Aegilops tauschii Coss.: genealogical and ecological framework.

Matsuoka Y, Takumi S, Kawahara T - PLoS ONE (2008)

Bottom Line: Timing of flowering is a reproductive trait that has significant impact on fitness in plants.Subsequent genealogical and statistical analyses showed that (1) there exist significant longitudinal and latitudinal clines in flowering time at the species level, (2) the early-flowering phenotype evolved in two intraspecific lineages, (3) in Asia, winter temperature was an environmental factor that affected the longitudinal clinal pattern of flowering time variation, and (4) in Transcaucasus-Middle East, some latitudinal factors affected the geographic pattern of flowering time variation.Postglacial southward dispersal from the TDV zone seems to have been driven by lineages that evolved short-flowering-time phenotypes through different genetic mechanisms in Transcaucasus-Middle East and Asia.

View Article: PubMed Central - PubMed

Affiliation: Fukui Prefectural University, Matsuoka, Eiheiji, Yoshida, Fukui, Japan. matsuoka@fpu.ac.jp

ABSTRACT
Timing of flowering is a reproductive trait that has significant impact on fitness in plants. In contrast to recent advances in understanding the molecular basis of floral transition, few empirical studies have addressed questions concerning population processes of flowering time diversification within species. We analyzed chloroplast DNA genealogical structure of flowering time variation in central Eurasian wild wheat Aegilops tauschii Coss. using 200 accessions that represent the entire species range. Flowering time measured as days from germination to flowering varied from 144.0 to 190.0 days (average 161.3 days) among accessions in a common garden/greenhouse experiment. Subsequent genealogical and statistical analyses showed that (1) there exist significant longitudinal and latitudinal clines in flowering time at the species level, (2) the early-flowering phenotype evolved in two intraspecific lineages, (3) in Asia, winter temperature was an environmental factor that affected the longitudinal clinal pattern of flowering time variation, and (4) in Transcaucasus-Middle East, some latitudinal factors affected the geographic pattern of flowering time variation. On the basis of palaeoclimatic, biogeographic, and genetic evidence, the northern part of current species' range [which was within the temperate desert vegetation (TDV) zone at the Last Glacial Maximum] is hypothesized to have harbored species refugia. Postglacial southward dispersal from the TDV zone seems to have been driven by lineages that evolved short-flowering-time phenotypes through different genetic mechanisms in Transcaucasus-Middle East and Asia.

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Related in: MedlinePlus

Geographic clines of flowering time.A) The relationship between latitude of origin and flowering time (regression coefficient±SE = 1.61±0.14, P<0.0001). B) The relationship between longitude of origin and flowering time (regression coefficient±SE = −0.34±0.05, P<0.0001).
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pone-0003138-g004: Geographic clines of flowering time.A) The relationship between latitude of origin and flowering time (regression coefficient±SE = 1.61±0.14, P<0.0001). B) The relationship between longitude of origin and flowering time (regression coefficient±SE = −0.34±0.05, P<0.0001).

Mentions: Flowering time (i.e., the mean of the three data points) among accessions varied from 144.0 to 190.0 days (mean = 161.3 days). On the basis of flowering time variation (Fig. 3), we categorized the 200 accessions into three phenotypic groups: early-flowering (flowering time <157.0 days, 51 accessions), intermediate-flowering (157.0 days≤flowering time <169.0 days, 122 accessions), and late-flowering (flowering time ≥169.0 days, 27 accessions). Geographically, longitudinal and latitudinal clines were recognizable, with most early-flowering accessions from southern (especially southeastern) habitats and late-flowering accessions from northern habitats (Fig. 1 and 4). The intermediate-flowering accessions were widely spread across the species' range. These results were consistent with [22], in which the authors examined the growth habit of 31 accessions collected from Iran, Afghanistan, and Pakistan and found that early-flowering populations occur in Afghanistan and Pakistan. Accordingly, we assessed the significance of these clines by multiple regression analysis using latitude and longitude as independent variables and flowering times as the response variable. This approach was taken because there was a correlation between latitude and longitude for the origin of accessions (r = −0.45, P<0.0001). Significant effects on flowering time were detected for both latitude (P<0.0001) and longitude (P = 0.0003) (Table 1).


Flowering time diversification and dispersal in central Eurasian wild wheat Aegilops tauschii Coss.: genealogical and ecological framework.

Matsuoka Y, Takumi S, Kawahara T - PLoS ONE (2008)

Geographic clines of flowering time.A) The relationship between latitude of origin and flowering time (regression coefficient±SE = 1.61±0.14, P<0.0001). B) The relationship between longitude of origin and flowering time (regression coefficient±SE = −0.34±0.05, P<0.0001).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2519791&req=5

pone-0003138-g004: Geographic clines of flowering time.A) The relationship between latitude of origin and flowering time (regression coefficient±SE = 1.61±0.14, P<0.0001). B) The relationship between longitude of origin and flowering time (regression coefficient±SE = −0.34±0.05, P<0.0001).
Mentions: Flowering time (i.e., the mean of the three data points) among accessions varied from 144.0 to 190.0 days (mean = 161.3 days). On the basis of flowering time variation (Fig. 3), we categorized the 200 accessions into three phenotypic groups: early-flowering (flowering time <157.0 days, 51 accessions), intermediate-flowering (157.0 days≤flowering time <169.0 days, 122 accessions), and late-flowering (flowering time ≥169.0 days, 27 accessions). Geographically, longitudinal and latitudinal clines were recognizable, with most early-flowering accessions from southern (especially southeastern) habitats and late-flowering accessions from northern habitats (Fig. 1 and 4). The intermediate-flowering accessions were widely spread across the species' range. These results were consistent with [22], in which the authors examined the growth habit of 31 accessions collected from Iran, Afghanistan, and Pakistan and found that early-flowering populations occur in Afghanistan and Pakistan. Accordingly, we assessed the significance of these clines by multiple regression analysis using latitude and longitude as independent variables and flowering times as the response variable. This approach was taken because there was a correlation between latitude and longitude for the origin of accessions (r = −0.45, P<0.0001). Significant effects on flowering time were detected for both latitude (P<0.0001) and longitude (P = 0.0003) (Table 1).

Bottom Line: Timing of flowering is a reproductive trait that has significant impact on fitness in plants.Subsequent genealogical and statistical analyses showed that (1) there exist significant longitudinal and latitudinal clines in flowering time at the species level, (2) the early-flowering phenotype evolved in two intraspecific lineages, (3) in Asia, winter temperature was an environmental factor that affected the longitudinal clinal pattern of flowering time variation, and (4) in Transcaucasus-Middle East, some latitudinal factors affected the geographic pattern of flowering time variation.Postglacial southward dispersal from the TDV zone seems to have been driven by lineages that evolved short-flowering-time phenotypes through different genetic mechanisms in Transcaucasus-Middle East and Asia.

View Article: PubMed Central - PubMed

Affiliation: Fukui Prefectural University, Matsuoka, Eiheiji, Yoshida, Fukui, Japan. matsuoka@fpu.ac.jp

ABSTRACT
Timing of flowering is a reproductive trait that has significant impact on fitness in plants. In contrast to recent advances in understanding the molecular basis of floral transition, few empirical studies have addressed questions concerning population processes of flowering time diversification within species. We analyzed chloroplast DNA genealogical structure of flowering time variation in central Eurasian wild wheat Aegilops tauschii Coss. using 200 accessions that represent the entire species range. Flowering time measured as days from germination to flowering varied from 144.0 to 190.0 days (average 161.3 days) among accessions in a common garden/greenhouse experiment. Subsequent genealogical and statistical analyses showed that (1) there exist significant longitudinal and latitudinal clines in flowering time at the species level, (2) the early-flowering phenotype evolved in two intraspecific lineages, (3) in Asia, winter temperature was an environmental factor that affected the longitudinal clinal pattern of flowering time variation, and (4) in Transcaucasus-Middle East, some latitudinal factors affected the geographic pattern of flowering time variation. On the basis of palaeoclimatic, biogeographic, and genetic evidence, the northern part of current species' range [which was within the temperate desert vegetation (TDV) zone at the Last Glacial Maximum] is hypothesized to have harbored species refugia. Postglacial southward dispersal from the TDV zone seems to have been driven by lineages that evolved short-flowering-time phenotypes through different genetic mechanisms in Transcaucasus-Middle East and Asia.

Show MeSH
Related in: MedlinePlus