Prosopis laevigata microsatellite and sequence alignment data

Patterns of genetic and phylogeographic structure and recent population
history of plant species in the Mexican arid zones has been scarcely
investigated. Prosopis laevigata is the most widely spread species of
mesquite in Mexico, with extensive populations in the arid and semi-arid
zones of the central and northern plateaus and scattered presence in
southern Mexico. We evaluated the genetic and phylogeographic structure of
this species to infer its recent demographic history. We genotyped six
nuclear microsatellite loci and sequenced the psbA3´-trnH chloroplast DNA
(cpDNA) region in individuals from 21 populations covering the whole
distribution of the species. Nuclear genetic diversity was moderately high
(HE=0.527) and genetic differentiation was moderate (FST=0.16). A positive
correlation between genetic diversity and latitude was observed. The cpDNA
analyses indicated a lack of phylogeographic structure in P. laevigata
(GST=0.090, NST=0.101; P=0.497). Historical demography statistics
indicated a population expansion supported by a skyline plot analysis, the
star-like shape of the haplotype network, and the unimodal shape of the
mismatch distribution. Ecological niche modeling suggested a contracted
distribution into west-central Mexico during the Last Interglacial (~140
Ka), followed by an expansion in both northwards and southwards directions
in the Last Glacial Maximum (~22 Ka), which continued in the mid-Holocene
(~6 Ka) and the present. Results are congruent with a recent population
growth and colonization of newly opened arid zones by P. laevigata
populations. This pattern is consistent with the high capacity of
colonization of nutrient-poor areas, high germination rates and resistance
to drought reported for Prosopis species

墨西哥干旱地区植物物种的遗传与系统地理结构模式及近期种群历史尚未得到充分研究。Prosopis laevigata是墨西哥分布最广的牧豆树（mesquite）物种，在中部和北部高原的干旱及半干旱区域具有广泛种群，在墨西哥南部则呈零散分布。本研究评估了该物种的遗传与系统地理结构，以推断其近期种群历史。我们对覆盖该物种全分布区的21个种群个体进行了6个核微卫星位点（nuclear microsatellite loci）的基因分型，并对叶绿体DNA（cpDNA）的psbA3´-trnH区域进行了测序。核遗传多样性中等偏高（HE=0.527），遗传分化程度中等（FST=0.16）。观察到遗传多样性与纬度之间存在正相关关系。cpDNA分析表明P. laevigata缺乏系统地理结构（GST=0.090，NST=0.101；P=0.497）。历史种群统计分析显示种群存在扩张，这一结论得到天际线图分析、单倍型网络的星状结构以及错配分布的单峰形态的支持。生态位模型（Ecological niche modeling）表明，该物种在末次间冰期（约14万年前）的分布收缩至墨西哥中西部，随后在末次盛冰期（约2.2万年前）向南北双向扩张，并在中全新世（约6千年前）及至今持续扩张。研究结果与P. laevigata种群近期的增长及对新生干旱区域的殖民化过程一致。这种模式与牧豆树属（Prosopis）物种已报道的在贫营养区域的高殖民能力、高萌发率及耐旱性相符。