鸟类分子系统地理学研究进展

分子系统地理学是当代生物地理学的重要分支,是以分子生物学方法重建种内和种上水平的系统发育关系,阐释进化历史,并通过分析近缘生物类群的系统发育关系与其空间和时间分布格局间的相关性构建生物区系历史的研究,是分子生物学与生物地理学结合的产物。中性进化学说和溯祖理论分析的建立,以及线粒体DNA和微卫星标记等分子遗传标记的应用,为分子系统地理学研究的开展提供了理论和实践基础。近年来,分子系统地理方法在鸟类学研究中的应用揭示了许多不同于传统认知的发现,为准确而深入的了解鸟类分子系统地理格局的差异和不同类群的起源中心提供了新颖的证据。目前的研究多从隔离分化说和扩散说的角度对鸟类分子系统地理格局的成因进行分析,而迁徙行为不同对鸟类系统地理格局的影响为成因的解释提供了新的角度。结合区域特点的比较分子系统地理研究,在更广泛的地域和更多类群中开展研究是我国鸟类分子系统地理研究的方向。此外,展望了第二代测序技术对分子生态生物地理研究具有的潜在促进作用。     

啮齿动物分子系统地理学研究进展

系统地理学是研究种间及种内不同种群的形成、现有分布格局的历史原因和演化过程的一门学科。基于分子水平,能够更准确地界定物种分布格局,促进分子系统地理学的形成和发展。近年来,分子系统地理研究的开展,促进了对啮齿动物物种分布格局形成机制的理解。对啮齿动物的种内及种上分类阶元的系统演化关系、起源中心与演化历程、影响系统地理格局的因素、鼠害防控和保护生物学等分子系统地理学方面的研究进行了综述。并提出了啮齿动物分子系统地理学未来发展的四点展望:1)综合性系统地理学研究;2)区域系统地理学研究;3)物种演化的全面系统研究;4)新型分子标记和分析方法的发展。     

青藏高原及其周边地区高山植物谱系地理学研究进展

青藏高原及其周边地区是世界上高山植物最丰富的地区,通过谱系地理学研究可以探讨高山植物演化历史与高原隆升和第四纪冰期的关系。根据对已经报道的36种高山植物的谱系地理分析,其谱系地理模式主要表现为:一、冰期退却到高原边缘的避难所,冰后期回迁到高原面;二、地理隔离造成冰期存在多处避难所(含微型避难所),冰后期发生局域性扩张。青藏高原在晚第三纪的快速隆升促进了物种的分化和成种,而第四纪冰期更是加剧了物种的快速分化,高原隆升和第四纪周期性气候波动是形成青藏高原高山植物现代谱系地理格局的主要原因。横断山脉地区作为第四纪冰期高山植物的主要避难所,在进化生物学和保护生物学方面具有重要启示。最后在物种选择、采样策略、基因片段选择和研究方法等4个方面提出青藏高原地区谱系地理学的研究方向。     

Comparative phylogeography of Nearctic and Palearctic fishes

Combining phylogeographic data from mitochondrial DNA (mtDNA) of Nearctic and Palearctic freshwater and anadromous fishes, we used a comparative approach to assess the influence of historical events on evolutionary patterns and processes in regional fish faunas. Specifically, we (i) determined whether regional faunas differentially affected by Pleistocene glaciations show predictable differences in phylogeographic patterns; (ii) evaluated how processes of divergence and speciation have been influenced by such differential responses; and (iii) assessed the general contribution of phylogeographic studies to conservation issues. Comparisons among case studies revealed fundamental differences in phylogeographic patterns among regional faunas. Tree topologies were typically deeper for species from nonglaciated regions compared to northern species, whereas species with partially glaciated ranges were intermediate in their characteristics. Phylogeographic patterns were strikingly similar among southern species, whereas species in glaciated areas showed reduced concordance. The extent and locations of secondary contact among mtDNA lineages varied greatly among northern species, resulting in reduced intraspecific concordance of genetic markers for some northern species. Regression analysis of phylogeographic data for 42 species revealed significant latitudinal shifts in intraspecific genetic diversity. Both relative nucleotide diversity and estimates of evolutionary effective population size showed significant breakpoints matching the median latitude for the southern limit of the Pleistocene glaciations. Similarly, analysis of clade depth of phylogenetically distinct lineages vs. area occupied showed that evolutionary dispersal rates of species from glaciated and nonglaciated regions differed by two orders of magnitude. A negative relationship was also found between sequence divergence among sister species as a function of their median distributional latitude, indicating that recent bursts of speciation events have occurred in deglaciated habitats. Phylogeographic evidence for parallel evolution of sympatric northern species pairs in postglacial times suggested that differentiation of cospecific morphotypes may be driven by ecological release. Altogether, these results demonstrate that comparative phylogeography can be used to evaluate not only phylogeographic patterns but also evolutionary processes. As well as having significant implications for conservation programs, this approach enables new avenues of research for examining the regional, historical, and ecological factors involved in shaping intraspecific genetic diversity.     

INTRASPECIFIC PHYLOGEOGRAPHY ACROSS THE POINT CONCEPTION BIOGEOGRAPHIC BOUNDARY

Recent studies of intraspecific phylogeography have suggested that the geographic location of genetic discontinuities, or phylogeographic breaks, may frequently coincide with biogeographic boundaries. The concordance is hypothesized to reflect similarity in the processes governing species boundaries and intraspecific lineage boundaries. This concordance has not, however, been widely tested. In the case of the Point Conception biogeographic boundary between the Oregonian and Californian marine biotas, only the supralittoral copepod Tigriopus californicus has been found to have a coincident phylogeographic break. Here I show that the apparent relationship between this break and Point Conception was, in fact, an artifact of insufficient geographic sampling. Mitochondrial DNA analyses of T. californicus populations between Morro Bay and San Diego reveal at least five equally deep phylogeographic breaks in the region (where only one biogeographic boundary is recognized). Limited nuclear DNA sequence data and allozyme data also support the occurrence of multiple genetic discontinuities along this geographic range. Lack of one-to-one correspondence between intraspecific phylogeography and biogeographic boundaries indicates that the processes affecting the genetic differentiation of populations of T. californicus differ from those responsible for determining species distributional limits at the Point Conception biogeographic boundary. A review of genetic data from other species also fails to provide evidence for concordance of biogeography and intraspecific phylogeography across Point Conception. I suggest that the concordance of phylogeography with biogeography will only be pronounced where the biogeographic boundary separates biotas that are phylogenetically related. The numerous cases of interspecific hybrid zones in the region of Cape Canaveral, for example, indicate that many sister-species pairs occur across this biogeographic boundary. Such hybrid zones are not common at Point Conception, and there appears to be no cases of intraspecific phylogeographic breaks associated with this well-recognized biogeographic boundary.     

Contrasting insights provided by single and multispecies data in a regional comparative phylogeographic study

Many single‐species freshwater phylogeographic studies have been carried out in south‐east Queensland; however comparative phylogeography requires multiple lines of evidence to infer deep, significant relationships between landscape and biota. The present study aimed to test conclusions resulting from single taxon studies in a multispecies comparative framework: (1) how influential are river basins in the genetic structure of freshwater species; (2) are there biogeographic frontiers between groups of basins; and (3) could deep intraspecific lineages be explained by a single event? New and existing data from 33 freshwater species (23 fishes and 10 crustaceans) were combined, and both standard single‐species analyses (haplotype networks, genetic distances, Φ_ST) and multispecies methods (hierarchical ABC) were carried out for 1814 sequences from eight basins. More than half of the species displayed a high phylogeographic structure and contained at least two distinct lineages. Almost all of the lineage divergences displayed an element of north/south geographic breaks, with the most influential boundary being between the Mary and Brisbane rivers. Of the 11 basin‐pair multispecies coalescent analyses, four implied a single divergence as being most likely. A regional analysis of deep lineages within 16 taxon‐pairs resulted in a strongly supported inference of a single divergence, probably dating to the Pleistocene. Basin boundaries are a key determinant of phylogeographic patterns for most of these freshwater species, although the specific biogeographic relationship between basins often varies depending on the species. There are a number of influential biogeographic frontiers, with the Brisbane‐Mary being the most important. The finding that a single event may be responsible for multiple deep lineages across the region implies that a highly influential climate change event may have been detected. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 554–569.     

Comparative phylogeography as an integrative approach to historical biogeography

Phylogeography has become a powerful approach for elucidating contemporary geographical patterns of evolutionary subdivision within species and species complexes. A recent extension of this approach is the comparison of phylogeographic patterns of multiple co-distributed taxonomic groups, or 'comparative phylogeography.' Recent comparative phylogeographic studies have revealed pervasive and previously unrecognized biogeographic patterns which suggest that vicariance has played a more important role in the historical development of modern biotic assemblages than current taxonomy would indicate. Despite the utility of comparative phylogeography for uncovering such 'cryptic vicariance', this approach has yet to be embraced by some researchers as a valuable complement to other approaches to historical biogeography. We address here some of the common misconceptions surrounding comparative phylogeography, provide an example of this approach based on the boreal mammal fauna of North America, and argue that together with other approaches, comparative phylogeography can contribute importantly to our understanding of the relationship between earth history and biotic diversification.     

The odd couple: contrasting phylogeographic patterns in two sympatric sibling species of woodlouse‐hunter spiders in the Canary Islands

Comparative phylogeography seeks for commonalities in the spatial demographic history of sympatric organisms to characterize the mechanisms that shaped such patterns. The unveiling of incongruent phylogeographic patterns in co‐occurring species, on the other hand, may hint to overlooked differences in their life histories or microhabitat preferences. The woodlouse‐hunter spiders of the genus Dysdera have undergone a major diversification on the Canary Islands. The species pair Dysdera alegranzaensis and Dysdera nesiotes are endemic to the island of Lanzarote and nearby islets, where they co‐occur at most of their known localities. The two species stand in sharp contrast to other sympatric endemic Dysdera in showing no evidence of somatic (non‐genitalic) differentiation. Phylogenetic and population genetic analyses of mitochondrial cox1 sequences from an exhaustive sample of D. alegranzaensis and D. nesiotes specimens, and additional mitochondrial (16S, L1, nad1) and nuclear genes (28S, H3) were analysed to reveal their phylogeographic patterns and clarify their phylogenetic relationships. Relaxed molecular clock models using five calibration points were further used to estimate divergence times between species and populations. Striking differences in phylogeography and population structure between the two species were observed. Dysdera nesiotes displayed a metapopulation‐like structure, while D. alegranzaensis was characterized by a weaker geographical structure but greater genetic divergences among its main haplotype lineages, suggesting more complex population dynamics. Our study confirms that co‐distributed sibling species may exhibit contrasting phylogeographic patterns in the absence of somatic differentiation. Further ecological studies, however, will be necessary to clarify whether the contrasting phylogeographies may hint at an overlooked niche partitioning between the two species. In addition, further comparisons with available phylogeographic data of other eastern Canarian Dysdera endemics confirm the key role of lava flows in structuring local populations in oceanic islands and identify localities that acted as refugia during volcanic eruptions.     

Intraspecific sequence variation of chloroplast DNA among the component species of evergreen broad-leaved forests in Japan

For the purpose of phylogeographic study of lucidophyllous (evergreen broad-leaved) forests in Japan, we surveyed intraspecific chloroplast DNA (cpDNA) variation in 41 component species of such forests. Intraspecific cpDNA variations were detected in 14 species. In 15 species and one species group, 16 non-coding cpDNA regions were examined to find intraspecific sequence variation. The extent of variation in these regions was compared. The largest amount of intraspecific variation was detected in the rps16 region. A relatively large amount of intraspecific variation was detected in the petD-rpoA, rpl16, and trnL-F regions. It is suggested that these regions of cpDNA would be useful for detecting intraspecific variation in plant species, and could provide valuable information for various research purposes.     

Comparative phylogeography of diadromous and freshwater daces of the genus <Emphasis Type="Italic">Tribolodon</Emphasis> (Cyprinidae)

Far Eastern daces, genus Tribolodon (Cyprinidae), are thought to have diversified and developed unique diadromous life histories under changing conditions in the Sea of Japan and the surrounding environment. To examine the relationships between life history traits, distribution, and genetic population structures, we conducted a comparative phylogeographic analysis using partial mtDNA sequence data from samples collected over almost the full ranges of all four Tribolodon species. Phylogenetic analyses revealed several intraspecific haplotype groups that differentiated in the early Pleistocene to the Pliocene with or without geographic overlaps. A time-calibrated phylogeny suggested that the relatively smaller geographic ranges of the strictly freshwater species, T. sachalinensis and T. nakamurai, were explained not by the recent origins of these species, but by their limited dispersal abilities and smaller historical population sizes. The wider-ranging diadromous species, T. brandtii and T. hakonensis, exhibited similar major phylogeographic structures in their distributions, but the chronological order and timing of formation of this structure largely differed between the two species. In addition to those differences, the overlapping patterns of the differentiated intraspecific lineages in these species suggest dynamic, but somewhat restricted dispersal during the Plio-Pleistocene. Tribolodon hakonensis, one of the most widespread species of East Asian freshwater fishes, included both common and unique phylogeographic patterns compared to other fish species; the unique patterns (i.e., its wide range across freshwater biogeographic boundaries like the sea and mountains) would reflect its ecological features as a remarkable generalist inhabiting lakes, upper and lower reaches of rivers, and even coastal areas.     

Cryptic Species? Patterns of Maternal and Paternal Gene Flow in Eight Neotropical Bats

Levels of sequence divergence at mitochondrial loci are frequently used in phylogeographic analysis and species delimitation though single marker systems cannot assess bi-parental gene flow. In this investigation I compare the phylogeographic patterns revealed through the maternally inherited mitochondrial COI region and the paternally inherited 7(th) intron region of the Dby gene on the Y-chromosome in eight common Neotropical bat species. These species are diverse and include members of two families from the feeding guilds of sanguivores, nectarivores, frugivores, carnivores and insectivores. In each case, the currently recognized taxon is comprised of distinct, substantially divergent intraspecific mitochondrial lineages suggesting cryptic species complexes. In Chrotopterus auritus, and Saccopteryx bilineata I observed congruent patterns of divergence in both genetic regions suggesting a cessation of gene flow between intraspecific groups. This evidence supports the existence of cryptic species complexes which meet the criteria of the genetic species concept. In Glossophaga soricina two intraspecific groups with largely sympatric South American ranges show evidence for incomplete lineage sorting or frequent hybridization while a third group with a Central American distribution appears to diverge congruently at both loci suggesting speciation. Within Desmodus rotundus and Trachops cirrhosus the paternally inherited region was monomorphic and thus does not support or refute the potential for cryptic speciation. In Uroderma bilobatum, Micronycteris megalotis and Platyrrhinus helleri the gene regions show conflicting patterns of divergence and I cannot exclude ongoing gene flow between intraspecific groups. This analysis provides a comprehensive comparison across taxa and employs both maternally and paternally inherited gene regions to validate patterns of gene flow. I present evidence for previously unrecognized species meeting the criteria of the genetic species concept but demonstrate that estimates of mitochondrial diversity alone do not accurately represent gene flow in these species and that contact/hybrid zones must be explored to evaluate reproductive isolation.     

Lizards as model organisms for linking phylogeographic and speciation studies

Lizards have been model organisms for ecological and evolutionary studies from individual to community levels at multiple spatial and temporal scales. Here we highlight lizards as models for phylogeographic studies, review the published population genetics/phylogeography literature to summarize general patterns and trends and describe some studies that have contributed to conceptual advances. Our review includes 426 references and 452 case studies: this literature reflects a general trend of exponential growth associated with the theoretical and empirical expansions of the discipline. We describe recent lizard studies that have contributed to advances in understanding of several aspects of phylogeography, emphasize some linkages between phylogeography and speciation and suggest ways to expand phylogeographic studies to test alternative pattern‐based modes of speciation. Allopatric speciation patterns can be tested by phylogeographic approaches if these are designed to discriminate among four alternatives based on the role of selection in driving divergence between populations, including: (i) passive divergence by genetic drift; (ii) adaptive divergence by natural selection (niche conservatism or ecological speciation); and (iii) socially‐mediated speciation. Here we propose an expanded approach to compare patterns of variation in phylogeographic data sets that, when coupled with morphological and environmental data, can be used to to discriminate among these alternative speciation patterns. [Correction made after online publication (28/07/2010): (minor deletion in the last line of the abstract)].     

Methods in comparative phylogeography, and their application to studying evolution in the north american aridlands

Historical biogeography and comparative phylogeography havemuch in common. Both seek to discover common historical patternsin the elements of biotas, although typically at different tiersof evolutionary history. Comparative phylogeography is basedon phylogeographic analyses of multiple taxa, usually widespreadspecies. By comparing the phylogeographic structures of numerouswidespread sympatric species, one can infer whether the currentfauna has been historically stable, as evidenced by the relativefrequency of geographically congruent reciprocally monophyleticgroups. Alternatively, if species distributions are ephemeralover evolutionary time, a mixture of phylogeographic structuresis expected. Coalescence analyses contribute information abouthistory irrespective of whether haplotype phylogenies are structuredor not. In the aridlands of North America, several isolatingevents are evident in the phylogeographic patterns of birds,mammals and herps. A mid-peninsular seaway in Baja California,dated at ca. one million years before present, had a pervasiveeffect, with 13 of 16 assayed species showing a concordant split.Hence, this community appears to have been a stable assemblageof species over the past one million years. In contrast, theavifauna of the Sonoran-Chihuahuan deserts consists of two specieswith a concordant split and three other species that are undifferentiatedacross both deserts. Hence, the species in this area have haddifferent histories. The Baja biota appears to resemble itsancestral configuration to a greater degree than the Sonoran-Chihuahuanone. A deeper evolutionary event separated taxa in Baja Californiafrom the eastern deserts, showing that the aridlands fauna wasaffected by events at different times resulting in overlaintiers of history.     

Sequence capture and next‐generation sequencing of ultraconserved elements in a large‐genome salamander

Amidst the rapid advancement in next‐generation sequencing (NGS) technology over the last few years, salamanders have been left behind. Salamanders have enormous genomes—up to 40 times the size of the human genome—and this poses challenges to generating NGS data sets of quality and quantity similar to those of other vertebrates. However, optimization of laboratory protocols is time‐consuming and often cost prohibitive, and continued omission of salamanders from novel phylogeographic research is detrimental to species facing decline. Here, we use a salamander endemic to the southeastern United States, Plethodon serratus, to test the utility of an established protocol for sequence capture of ultraconserved elements (UCEs) in resolving intraspecific phylogeographic relationships and delimiting cryptic species. Without modifying the standard laboratory protocol, we generated a data set consisting of over 600 million reads for 85 P. serratus samples. Species delimitation analyses support recognition of seven species within P. serratus sensu lato, and all phylogenetic relationships among the seven species are fully resolved under a coalescent model. Results also corroborate previous data suggesting nonmonophyly of the Ouachita and Louisiana regions. Our results demonstrate that established UCE protocols can successfully be used in phylogeographic studies of salamander species, providing a powerful tool for future research on evolutionary history of amphibians and other organisms with large genomes.     

Deciphering the global phylogeography of a coastal shrub (Scaevola taccada) reveals the influence of multiple forces on contemporary population structure

The phylogeography of coastal plant species is heavily influenced by past sealevel fluctuations, dispersal barriers, and life-history traits, such as long-distance dispersal ability of the propagules. Unlike the widely studied mangroves, phylogeographic patterns have remained mostly obscure for other coastal plant species. In this study, we sampled 42 populations of Scaevola taccada (Gaertn.) Roxb., a coastal shrub of the family Goodeniaceae, from 17 countries across its distribution range. We used five chloroplast DNA (cpDNA) and 14 nuclear microsatellite (simple sequence repeat [SSR]) markers to assess the influence of abiotic factors and population genetic processes on the phylogeographic pattern of the species. Geographical distribution of cpDNA haplotypes suggests that the species originated in Australia, followed by historical dispersal and expansion of its geographic range. Multiple abiotic factors, including the sealevel changes during the Pleistocene, the presence of landmasses like the Malay Peninsula, and contemporary oceanic circulation patterns, restricted gene flow between geographically distinct populations, thereby creating low haplotype diversity and a strong population structure. Population genetic processes acted on these isolated populations, leading to high nuclear genetic diversity and population differentiation, as revealed from analyzing the polymorphic SSR loci. Although genetic divergence was mostly concordant between cpDNA and SSR data, asymmetrical gene flow and ancestral polymorphism could explain the discordance in the detailed genetic structure. Overall, our findings indicate that abiotic factors and population genetic processes interactively influenced the evolutionary history and current phylogeographic pattern of S. taccada across its distribution range.     

Statistical phylogeography

While studies of phylogeography and speciation in the past have largely focused on the documentation or detection of significant patterns of population genetic structure, the emerging field of statistical phylogeography aims to infer the history and processes underlying that structure, and to provide objective, rather than ad hoc explanations. Methods for parameter estimation are now commonly used to make inferences about demographic past. Although these approaches are well developed statistically, they typically pay little attention to geographical history. In contrast, methods that seek to reconstruct phylogeographic history are able to consider many alternative geographical scenarios, but are primarily nonstatistical, making inferences about particular biological processes without explicit reference to stochastically derived expectations. We advocate the merging of these two traditions so that statistical phylogeographic methods can provide an accurate representation of the past, consider a diverse array of processes, and yet yield a statistical estimate of that history. We discuss various conceptual issues associated with statistical phylogeographic inferences, considering especially the stochasticity of population genetic processes and assessing the confidence of phylogeographic conclusions. To this end, we present some empirical examples that utilize a statistical phylogeographic approach, and then by contrasting results from a coalescent-based approach to those from Templeton's nested cladistic analysis (NCA), we illustrate the importance of assessing error. Because NCA does not assess error in its inferences about historical processes or contemporary gene flow, we performed a small-scale study using simulated data to examine how our conclusions might be affected by such unconsidered errors. NCA did not identify the processes used to simulate the data, confusing among deterministic processes and the stochastic sorting of gene lineages. There is as yet insufficient justification of NCA's ability to accurately infer or distinguish among alternative processes. We close with a discussion of some unresolved problems of current statistical phylogeographic methods to propose areas in need of future development.     

A striking lack of genetic diversity across the wide-ranging amphibian <Emphasis Type="Italic">Gastrophryne carolinensis</Emphasis> (Anura: Microhylidae)

We examine phylogeographic structure across a wide-ranging microhylid frog (Gastrophryne carolinensis) using both mitochondrial (mtDNA) and nuclear (AFLP) data. Species with similar ecological characteristics such as large range size, low vagility, or existence across known biogeographic barriers, often are comprised of multiple, cryptic lineages. Surprisingly, our analyses of both portions of the genome show very little phylogeographic or population genetic structure. The family Microhylidae is one of the largest families of anurans with over 60 genera and around 400 species distributed across much of the world (Americas, Asia, Africa, and Madagascar), but very few phylogeographic studies have assessed intraspecific genetic diversity across the mitochondrial and nuclear genomes. Our results suggest that G. carolinensis, one of only three species of microhylid native to the US, has experienced a severe population bottleneck with subsequent range expansion. Comparable molecular data from closely related microhylids, in addition to demographic and ecological analyses, will provide valuable insight into patterns of genetic diversity and the processes driving phylogeographic diversity in these wide-ranging frogs.     

分子系统地理学及其应用

分子系统地理学是20世纪70年代中期伴随着对线粒体DNA的认识而开始酝酿发展的,本文回顾了该学科自诞生以来的发展简史,阐述了其研究内容,着重从3个方面介绍了该领域在其它相关学科中的研究进展,总结了该学科存在的问题,并提出重点应解决的3个问题：1）将细胞器基因与遗传信息更为丰富的核基因相结合;2）合生理论在非平衡种群中的发展应用;3）提高对分化时间估计的精确性。     

Phylogeographically concordant chloroplast DNA divergence in sympatric Nothofagus s.s. How deep can it be?

? Here, we performed phylogenetic analyses and estimated the divergence times on mostly sympatric populations of five species within subgenus Nothofagus. We aimed to investigate whether phylogenetic relationships by nuclear internal transcribed spacer (ITS) and phylogeographic patterns by chloroplast DNA (cpDNA) mirror an ancient evolutionary history that was not erased by glacial eras. Extant species are restricted to Patagonia and share a pollen type that was formerly widespread in all southern land masses. Weak reproductive barriers exist among them. ? Fifteen cpDNA haplotypes resulted from the analysis of three noncoding regions on 330 individuals with a total alignment of 1794 bp. Nuclear ITS data consisted of 822 bp. We found a deep cpDNA divergence dated 32 Ma at mid-latitudes of Patagonia that predates the phylogenetic divergence of extant taxa. Other more recent breaks by cpDNA occurred towards the north. ? Complex paleogeographic features explain the genetic discontinuities. Long-lasting paleobasins and marine ingressions have impeded transoceanic dispersal during range expansion towards lower latitudes under cooler trends since the Oligocene. ? Cycles of hybridization-introgression among extant and extinct taxa have resulted in widespread chloroplast capture events. Our data suggest that Nothofagus biogeography will be resolved only if thorough phylogeographic analyses and molecular dating methods are applied using distinct genetic markers.