Demographic bottlenecks and low gene flow in remnant populations of the critically endangered <Emphasis Type="Italic">Berchemiella wilsonii</Emphasis> var<Emphasis Type="Italic">. pubipetiolata</Emphasis> (Rhamnaceae) inferred from microsatellite markers |
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Authors: | Ming Kang Jing Wang Hongwen Huang |
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Institution: | (1) Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei, 430074, China;(2) South China Botanical Garden/South China Institute of Botany, Chinese Academy of Sciences, Guangzhou, Guangdong, 510650, China |
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Abstract: | Berchemiella wilsonii var. pubipetiolata (Rhamnaceae) is an endangered plant with only four remnant populations in eastern China. Population genetic information is
essential for understanding population history and formulating conservation strategies for this species. Thirteen microsatellite
loci were used to investigate genetic variation and population structure of the four remnant populations. Moderate levels
of expected heterozygosity (H
E = 0.466–0.543) and low allelic diversity (A = 3.1–3.6 and A
R = 2.2–2.4, respectively) were observed within populations. Bottleneck tests found three out of four populations to deviate
from mutation-drift equilibrium under the two-phase model (TPM), suggesting a recent population decline, which is congruent
with known demographic history. The evolutionary history of the species seems dominated by genetic drift rather than gene
flow. Low historical gene flow was inferred from several different approaches and N
m ranged from 0.582 by the private allele method to 0.783 by the coalescent method. Contemporary gene flow was also found to
be even lower for only one first generation migrant was detected with individual-based assignment analysis. Restricted pollen
and seed dispersal as well as a recent decline in population size associated with habitat fragmentation may have contributed
to low levels of historical and contemporary gene flow, and resulted in a high genetic differentiation. Under this scenario,
Berchemiella wilsonii var. pubipetiolata populations are expected to display more pronounced population genetic structure in the future as a result of increased inbreeding
and genetic drift. |
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Keywords: | Assignment test Berchemiella wilsonii var pubipetiolata Equilibrium Gene flow Microsatellite |
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