Phylogeography of Tibouchina papyrus (Pohl) Toledo (Melastomataceae), an endangered tree species from rocky savannas, suggests bidirectional expansion due to climate cooling in the Pleistocene

Many endemic species present disjunct geographical distribution; therefore, they are suitable models to test hypotheses about the ecological and evolutionary mechanisms involved in the origin of disjunct distributions in these habitats. We studied the genetic structure and phylogeography of Tibouchina papyrus (Melastomataceae), endemic to rocky savannas in Central Brazil, to test hypothesis of vicariance and dispersal in the origin of the disjunct geographical distribution. We sampled 474 individuals from the three localities where the species is reported: Serra dos Pirineus, Serra Dourada, and Serra de Natividade. Analyses were based on the polymorphisms at cpDNA and on nuclear microsatellite loci. To test for vicariance and dispersal we constructed a median-joining network and performed an analysis of molecular variance (AMOVA). We also tested population bottleneck and estimated demographic parameters and time to most recent common ancestor (TMRCA) using coalescent analyses. A remarkable differentiation among populations was found. No significant effect of population expansion was detected and coalescent analyses showed a negligible gene flow among populations and an ancient coalescence time for chloroplast genome. Our results support that the disjunct distribution of T. papyrus may represent a climatic relict. With an estimated TMRCA dated from ～836.491 ± 107.515 kyr BP (before present), we hypothesized that the disjunct distribution may be the outcome of bidirectional expansion of the geographical distribution favored by the drier and colder conditions that prevailed in much of Brazil during the Pre-Illinoian glaciation, followed by the retraction as the climate became warmer and moister.     

Phylogenetic tests of distribution patterns in South Asia: towards an integrative approach

The last four decades have seen an increasing integration of phylogenetics and biogeography. However, a dearth of phylogenetic studies has precluded such biogeographic analyses in South Asia until recently. Noting the increase in phylogenetic research and interest in phylogenetic biogeography in the region, we outline an integrative framework for studying taxon distribution patterns. While doing so, we pay particular attention to challenges posed by the complex geological and ecological history of the region, and the differences in distribution across taxonomic groups. We outline and compare three widely used phylogenetic biogeographic approaches: topology-based methods (TBMs), pattern-based methods (PBMs) and event-based methods (EBMs). TBMs lack a quantitative framework and utilize only part of the available phylogenetic information. Hence, they are mainly suited for preliminary enquiries. Both PBMs and EBMs have a quantitative framework, but we consider the latter to be particularly suited to the South Asian context since they consider multiple biogeographic processes explicitly, and can accommodate a reticulated history of areas. As an illustration, we present a biogeographic analysis of endemic Sri Lankan agamid lizards. The results provide insights into the relative importance of multiple processes and specific zones in the radiation of two speciose lizard clades.     

中国嵩草属植物地理分布模式和适应的气候特征

为了明确嵩草属(Kobresia)植物分布与气候要素的关系, 收集了嵩草属植物地理分布资料和气象台站气候数据, 应用ArcGIS软件及SPSS软件中的聚类分析方法, 分析了嵩草属植物地理分布模式和适应的气候特征。结果显示: 嵩草属植物分布在青藏高原、西北、华北和东北部分地区, 广泛分布13种, 间断分布10种, 分布海拔为1 400-5 000 m, 经度和纬度范围分别为81-112° E和23-46° N。嵩草属植物适应的气候要素平均值范围: 年生物学温度为4-19 ℃, 年平均气温为0-20 ℃, 年平均最高气温为7-28 ℃, 年平均最低气温为-6-16 ℃, 极端最高气温为25-40 ℃, 极端最低气温为-37.0-0.0 ℃, 1月和7月平均气温分别为-14-13 ℃和11-24 ℃, 1月和7月最高气温分别为-7-23 ℃和18-30 ℃, 1月和7月最低气温分别为-22-7 ℃和5-20 ℃, 春夏秋冬季气温分别为-4-19 ℃、9-23 ℃、6-21 ℃和-11-15 ℃, 温暖指数为23-159 ℃, 寒冷指数为-36-0 ℃, 年降水量为154-1 500 mm, 春夏秋冬降水量分别为19-135 mm、53-662 mm、48-545 mm和5-92 mm, Holdridge潜在蒸散量为261-1 100 mm, Thornthwaite潜在蒸发量为399-895 mm, 干燥度为167-786, 湿润指数为179-816, 4-10月日照时数为990-2 100 h。在热量要素平均值较低和中等、降水量与干燥湿润度平均值中等或辐射时数平均值较高范围下分布种数较多。嵩草属植物适应的气候要素极值, 年平均气温最小最大值范围为-6-21 ℃, 年平均最低气温最小值最高气温最大值范围为-12-28 ℃, 极端最低气温最小值最高气温最大值范围为-48-42 ℃, 最冷最热月气温范围为-32-33 ℃, 冬夏季最低最高气温范围为-20-25 ℃, 降水量最小最大值范围为15-1 800 mm, 干燥度最小最大值范围为7-890, 日照时数最小最大值范围为701-2 300 h。在热量要素极值较低、降水量及干燥度极值中等或日照时数极值较大范围下分布种数较多。说明嵩草属植物主要适应于低温亚湿润型和中温湿润型气候。     

气候因子对橘小实蝇生长发育及地理分布的影响

文章概述橘小实蝇Bactrocera dorsalis(Hendel)生活史、地理分布和生态要求的基础上,分析温度、湿度、降雨以及气候因子与橘小实蝇生长发育的关系,以及对橘小实蝇地理分布的影响。综述结果表明:喜湿热,厌干冷是橘小实蝇主要的生态学特征,低温与干旱不利于其生长发育;温度是橘小实蝇纬度分布中最主要的影响因子,冬季低温是中高纬度分布的主要限制因子,夏季高温是低纬度地区的限制因素之一,降雨影响橘小实蝇在经度上的分布范围。     

未来气候变化情景下中国植物物种地理分布变化趋势研究进展（附录）

分析气候变化对植物地理分布的影响,对生物多样性保护适应气候变化有重要意义。该文基于2010年以来发表的220篇文献,总结分析了未来气候变化情景下中国植物地理分布变化的研究进展,讨论了存在的问题和不足,展望了未来的研究方向。结果表明：(1)自2010年以来,我国学者对未来气候变化情景下中国1 058种植物中地理分布变化特征进行了分析,其中地理分布变化信息明确的仅有636种。(2)未来气候变化情景下,518种被子植物中195种地理分布范围呈增加趋势,245种呈减少趋势;57种裸子植物中12种地理分布范围呈增加趋势,38种呈减少趋势;1种蕨类植物分布范围呈增加趋势;60种苔藓植物中7种地理分布范围呈增加趋势,53种呈减少趋势;其他植物的地理分布范围表现为不一致或缺少变化信息。(3)未来气候变化情景下,植物地理分布格局明确呈现向西北、华北或东北迁移的有137种,同时向高纬度和高海拔迁移的有19种,仅向高纬度迁移的有125种,其他植物表现为不同方向迁移或缺乏迁移信息。(4)未来气候变化情景下,在概率大于0.6时,约有32种被子植物、42种裸子植物和48种苔藓植物地理分布范围将面临完全丧失的风险,而不考虑概率下约有57种被子植物和96种裸子植物地理分布范围将面临丧失的风险。研究不足包括(1)研究植物种数较少;(2)选择气候变化情景和模型单一;(3)缺乏对气候和其他环境因子综合考虑与多模型的对比研究;(4)缺少系统分析未来气候变化情景下植物地理分布范围丧失风险等。综上认为,未来在丰富研究植物种数的同时,需要加强利用多种气候变化情景,发展适合中国区域特色的生态位模型,开展多种气候变化情景下不同植物地理分布变化的对比研究,并且也需要加强气候变化情景下植物地理分布范围丧失风险的分析等。     

Microsatellite DNA analyses of a highly disjunct New Zealand tree reveal strong differentiation and imply a formerly more continuous distribution

Although New Zealand is a biodiversity hotspot, there has been little genetic investigation of why so many of its threatened and uncommon plants have naturally disjunct distributions. We investigated the small tree Pseudopanax ferox (Araliaceae), which has a widespread but highly disjunct lowland distribution within New Zealand. Genotyping of nuclear microsatellites and a chloroplast locus revealed pronounced genetic differentiation and four principal genetic clusters. Our results indicate that the disjunct distribution is a product of vicariance rather than long‐distance dispersal. This highlights the need to preserve multiple populations when disjunct distributions are the result of vicariance, rather than focusing conservation efforts on a core area, in order to retain as much as possible of a species’ evolutionary legacy and potential. Additionally, based on our genetic findings and the ecology of P. ferox, we hypothesize that it was more continuously distributed during the drier (but not maximally colder) interstadials of glacial periods and/or on the fertile soils available immediately postglacial. We further hypothesize that P. ferox belongs to a suite of species of drought‐prone and/or fertile habitats whose distributions are actually restricted during warmer and wetter interglacial periods, despite being principally of the lowlands. Our genetic data for P. ferox are also the first consistent with the survival during the Last Glacial Maxima of a lowland tree at high latitudes in the south‐eastern South Island.