两种竹鸡线粒体DNA的遗传变异

采用PCR和直接测序的方法测定灰胸竹鸡(Bambusicola thoracica)与棕胸竹鸡(B.fytchii)线粒体DNA(mtDNA)控制区1142bp的序列,分析二者间的遗传变异。两种竹鸡间共发现32个变异位点,其中20个转换,12个颠换。灰胸竹鸡mtDNA控制区的碱基含量T34.26%、C25.98%、A24.84%和G14.96%,棕胸竹鸡的分别是T34.47%、C25.60%、A25.03%和G14.93%。t-检验分析显示,两种竹鸡mtDNA控制区的T和C含量差异显著。在系统发生树上,两种竹鸡在系统发生树各聚成一支,支持率达到100%。两种竹鸡间的遗传距离是0.0396。根据分子钟计算,它们大约在200万年前分歧进化。推测它们的物种形成主要受更新世第二次寒冷期的影响。

Genetic Variation between Bambusicola thoracica and B.fytchii Based on Mitochondrial DNA

Polymerase chain reaction and direct sequencing methods were used to analyze the genetic variation between Bambusicola thoracica and B.fytchii.A total of 1 142 nucleotides of the mitochondrial DNA control region were sequenced.There are 32 variable positions,with 20 transitions and 10 transversions.The nucleotide composition of B.thoracica mtDNA D-loop was:34.26% T,25.98% C,24.84% A and 14.96% G.That of B.fytchii was:34.47% T,25.60% C,25.03% A and 14.93% G.There were very significant differences in T and C nucleotide composition between the two bamboo partridges.The phylogenetic tree grouped two bamboo partridges into two deeply divergent clusters(supported by BP=100%).Genetic distance was 0.039 6 between the two partridges.Calibrated rates of molecular evolution suggested that they could have speciated 2.00 million years ago,affected by the Pleistocene second frigid.