Grobler Petrus C J, Daniels Savel R
Evolutionary Genomics Group, Department of Botany and Zoology Stellenbosch University Matieland South Africa.
Ecol Evol. 2024 Sep 13;14(9):e70285. doi: 10.1002/ece3.70285. eCollection 2024 Sep.
During the present study, the phylogeography of the wetland specialist, freshwater crab, , was investigated and compared to that of the ubiquitous, generalist, , using DNA sequence data from the mitochondrial cytochrome oxidase subunit one (COI). We inferred the evolutionary history of each species and compared their population-level genetic structure by constructing haplotype networks and using an analysis of molecular variation. Additionally, we explored the evolutionary relationship between southern African lentic and lotic freshwater crab species by examining the usefulness of carapace attributes in relation to genetic indices and a species' assumed dispersal capacity. In the lentic species, , a single interconnected haplocluster characterized by shared haplotypes was observed, suggesting marked maternal dispersal, a result corroborated by the low values. In contrast, for the lotic species, two distinct haploclusters and marked genetic differentiation was observed indicating the absence of maternal dispersal, a result corroborated by the high values. The phylogenetic relationship in was further investigated using a maximum likelihood and Bayesian inference analyses with the addition of sequence data from the mitochondrial 16S rRNA locus to estimate divergence times. Three species delimitation methods (ASAP, PTP, and bGMYC) were used to explore the presence of distinct lineages in . The phylogenetic results indicated that within two clades were present, while divergence time estimates suggest cladogenesis during the middle to late Pleistocene. The species delimitation methods used showed moderate congruence, however all oversplit the number of putative lineages. Our results indicated that is a species complex comprised of two cryptic lineages, occurring in sympatry contemporarily possibly alluding to secondary contact. Carapace height was found to have no discernible influence on the genetic indices and presumed dispersal capabilities of mainland southern African freshwater crab species. The importance of our results are discussed in terms of conservation of freshwater habitats.
在本研究中，利用线粒体细胞色素氧化酶亚基I（COI）的DNA序列数据，对湿地特有种淡水蟹的系统地理学进行了调查，并与常见的广布种进行了比较。我们推断了每个物种的进化历史，并通过构建单倍型网络和使用分子变异分析来比较它们在种群水平上的遗传结构。此外，我们通过研究甲壳特征与遗传指标以及物种假定扩散能力之间的关系，探讨了南部非洲静水和流水淡水蟹物种之间的进化关系。在静水物种中，观察到一个以共享单倍型为特征的单一相互连接的单倍型簇，表明有明显的母系扩散，低FST值证实了这一结果。相比之下，对于流水物种，观察到两个不同的单倍型簇和明显的遗传分化，表明不存在母系扩散，高FST值证实了这一结果。利用最大似然法和贝叶斯推断分析，并添加线粒体16S rRNA基因座的序列数据来估计分歧时间，进一步研究了该属的系统发育关系。使用三种物种界定方法（ASAP、PTP和bGMYC）来探索该属中不同谱系的存在。系统发育结果表明，该属内存在两个分支，而分歧时间估计表明分支发生在更新世中期至晚期。所使用的物种界定方法显示出适度的一致性，但都过度划分了假定谱系的数量。我们的结果表明，该属是一个由两个隐存谱系组成的物种复合体，目前同时存在于同域分布中，这可能暗示了二次接触。发现甲壳高度对南部非洲大陆淡水蟹物种的遗传指标和假定扩散能力没有明显影响。我们从淡水栖息地保护的角度讨论了研究结果的重要性。
