Reconstruction of the spatio-temporal diversification and ecological niche evolution of Helianthemum (Cistaceae) in the Canary Islands using genotyping-by-sequencing data

Background and AimsSeveral biogeographical models have been proposed to explain the colonization and diversification patterns of Macaronesian lineages. In this study, we calculated the diversification rates and explored what model best explains the current distribution of the 15 species endemic to the Canary Islands belonging to Helianthemum sect. Helianthemum (Cistaceae).MethodsWe performed robust phylogenetic reconstructions based on genotyping-by-sequencing data and analysed the timing, biogeographical history and ecological niche conservatism of this endemic Canarian clade.Key ResultsOur phylogenetic analyses provided strong support for the monophyly of this clade, and retrieved five lineages not currently restricted to a single island. The pristine colonization event took place in the Pleistocene (~1.82 Ma) via dispersal to Tenerife by a Mediterranean ancestor.ConclusionsThe rapid and abundant diversification (0.75–1.85 species per million years) undergone by this Canarian clade seems the result of complex inter-island dispersal events followed by allopatric speciation driven mostly by niche conservatism, i.e. inter-island dispersal towards niches featuring similar environmental conditions. Nevertheless, significant instances of ecological niche shifts have also been observed in some lineages, making an important contribution to the overall diversification history of this clade.     

Effects of aerial dispersal, habitat specialisation, and landscape structure on spider distribution across fragmented grey dunes

Species distribution patterns have been explained by Hutchinson's niche theory, metapopulation theory and source-sink theory. Empirical verification of this framework, however, remains surprisingly scant. In this paper, we test the hypothesis that landscape characteristics (patch size and connectivity), aerial dispersal ability and niche breadth interact in explaining distribution patterns of 29 spider species inhabiting fragmented grey dunes. Distribution patterns only depended on aerial dispersal potential, and the interaction between patch connectivity and area. Niche breadth, measured as the degree of habitat specialisation in the total coastal dune system, did not contribute to the observed distribution patterns. Additional variation in patch occupancy frequency was strongly species-dependent and was determined by different responses to the degree of patch connectivity for ballooning dispersal. Results from this study suggest that dispersal ability largely affects our perception of a species "fundamental niche", and that source-sink and metapopulation dynamics may have a major impact on the distribution of species. From a conservation point of view, specialised (and hence intrinsically rare) species can be predicted to become rarer if fragmentation increases and connectivity decreases. This study is, to our knowledge, one of the few linking species distribution (and not patch occupancy, species diversity or richness) to landscape ecological (patch connectivity and area) and auto-ecological (niche breadth, dispersal potential) features.     

Spatial mismatches between plant biodiversity facets and evolutionary legacy in the vicinity of a major Mediterranean city

The analyses of congruencies among biodiversity components address the issue of conservation priorities, but previously they have been done at coarse scales with limited relevance for conservation actions. Moreover, these former studies consider only the species level components of biodiversity and not the intra-specific evolutionary legacy that influences future biodiversity. This study represents the first assessment of congruencies between various components of plant biodiversity and the evolutionary legacy of a narrow endemic taxon (Arenaria provincialis, Caryophyllaceae). Assessment is conducted in the vicinity of a Mediterranean big city (Marseille, S.E. France) where habitats and flora are threatened by mass tourism and urban sprawl. Our analyses reveal that the different plant biodiversity facets assessed are spatially mismatched and unequally protected. Moreover, by using only species-level components of biodiversity as conservation targets we ignore crucial areas for the evolutionary legacy of this narrow endemic plant. Our results highlight the crucial role of phylogeography as a criterion to target the genetic precursors of future biodiversity in conservation planning.     

The ecology of Lagarostrobos franklinii (Hook.f.) Quinn (Podocarpaceae) in Tasmania. 1. Distribution,floristics and environmental correlates

A state-wide survey of the endemic Tasmanian podocarp Lagarostrobos franklinii (Huon pine) resulted in the recognition of four major community types largely restricted to the river systems of western and southern Tasmania. Continuous variation was found between most of these communities. The floristic variability was found to be correlated with temperature, rainfall and geological gradients. It is suggested that the restricted nature of Huon pine distribution in Tasmania is associated with a slow terrestrial dispersal rate rather than a narrow fundamental niche. There is some evidence to suggest that the species has been further restricted by fire.     

Phylogeography sheds light on the central–marginal hypothesis in a Mediterranean narrow endemic plant

Background and Aims

Understanding the factors that shape variation in genetic diversity across the geographic ranges of species is an important challenge in the effort to conserve evolutionary processes sustaining biodiversity. The historical influences leading to a central–marginal organization of genetic diversity have been explored for species whose range is known to have expanded from refugia after glacial events. However, this question has rarely been addressed for Mediterranean endemic plants of azonal habitats such as rocky slopes or screes. In this context, this comprehensive study examined molecular and field data from Arenaria provincialis (Caryophyllaceae), a narrow endemic plant of south-eastern France.

Methods

Across the whole geographic range, an investigation was made of whether high levels of abundance and genetic diversity (estimated from amplified fragment length polymorphism markers) are centrally distributed, to evaluate the relevance of the central–marginal hypothesis. Phylogeographic patterns inferred from chloroplast DNA (cpDNA) were used, applying Bayesian methods to test the influence of past biogeographic events. Multivariate analysis combining phylogeographic and ecological data was used to reveal the historical and ecological distinctiveness of populations.

Key Results

Despite the narrow distribution of A. provincialis, a high level of nucleotide variation is found within cpDNA loci, supporting its persistence throughout the Pleistocene period. The area characterized by the highest genetic diversity is centrally located. Structured phylogeography and Bayesian factor analysis supported the hypothesis that the central area of the distribution was the source of both westward and eastward migrations, probably during arid periods of the Pleistocene, and more recently was a crossroads of backward migrations. By contrast, the two areas located today at the range limits are younger, have reduced genetic diversity and are marginal in the ecological gradients.

Conclusions

This study highlights a case of strong population distinctiveness within a narrow range. Phylogeography sheds light on the historical role of the areas centrally situated in the distribution. The current range size and abundance patterns are not sufficient to predict the organization of genetic diversity.     

Observational evidence that maladaptive gene flow reduces patch occupancy in a wild insect metapopulation

Theory predicts that dispersal throughout metapopulations has a variety of consequences for the abundance and distribution of species. Immigration is predicted to increase abundance and habitat patch occupancy, but gene flow can have both positive and negative demographic consequences. Here, we address the eco‐evolutionary effects of dispersal in a wild metapopulation of the stick insect Timema cristinae, which exhibits variable degrees of local adaptation throughout a heterogeneous habitat patch network of two host‐plant species. To disentangle the ecological and evolutionary contributions of dispersal to habitat patch occupancy and abundance, we contrasted the effects of connectivity to populations inhabiting conspecific host plants and those inhabiting the alternate host plant. Both types of connectivity should increase patch occupancy and abundance through increased immigration and sharing of beneficial alleles through gene flow. However, connectivity to populations inhabiting the alternate host‐plant species may uniquely cause maladaptive gene flow that counters the positive demographic effects of immigration. Supporting these predictions, we find the relationship between patch occupancy and alternate‐host connectivity to be significantly smaller in slope than the relationship between patch occupancy and conspecific‐host connectivity. Our findings illustrate the ecological and evolutionary roles of dispersal in driving the distribution and abundance of species.     

Phylogeography of the eight-barbel loach <Emphasis Type="Italic">Lefua nikkonis</Emphasis> (Cypriniformes: Nemacheilidae): how important were straits in northern Japan as biogeographical barriers?

Many straits in the Japanese archipelago have been proposed as biogeographical boundaries, but there is disagreement regarding their importance as historic barriers against dispersal of terrestrial and freshwater taxa. Mitochondrial DNA haplotype and phylogenetic analyses of Lefua nikkonis, a primary freshwater fish inhabiting northern Japan and descendent from Siberia, revealed that the species is genetically structured within its geographic range, but that two major haplotypes are widely distributed across the Ishikari Lowland of Hokkaido Island as well as across the Tsugaru Strait between Hokkaido and Honshu Islands, two well-known biogeographical boundaries of northern Japan. The two major haplotypes were separated from each other by only one mutational step, and many other haplotypes, including those endemic to the region south of these barriers, have diverged from the major haplotypes, suggesting rapid range expansion and local differentiation. Divergence-time estimates, based on vicariance of the Honshu endemic congener L. echigonia via uplift of the Central Highlands, demonstrated that the southward dispersal of L. nikkonis from Hokkaido Island to Honshu Island occurred less than 0.08–0.19 Mya, suggesting that a land bridge emerged at the Tsugaru Strait during the Riss glaciation. Given that other freshwater taxa crossed the strait earlier (during the Middle Pleistocene), it is likely that land bridges in the strait have repeatedly emerged. The fact that L. nikkonis invaded only the northern part of Honshu, and that many other freshwater species also have the limit of their distribution ranges in this area as well, indicates that a faunal transition zone might persist even without the Tsugaru Strait. Thus, straits and lowlands in northern Japan are likely to have been less important as dispersal barriers to freshwater taxa than is currently thought.     

Biogeographical network analysis of plant species distribution in the Mediterranean region

The delimitation of bioregions helps to understand historical and ecological drivers of species distribution. In this work, we performed a network analysis of the spatial distribution patterns of plants in south of France (Languedoc‐Roussillon and Provence‐Alpes‐Côte d'Azur) to analyze the biogeographical structure of the French Mediterranean flora at different scales. We used a network approach to identify and characterize biogeographical regions, based on a large database containing 2.5 million of geolocalized plant records corresponding to more than 3,500 plant species. This methodology is performed following five steps, from the biogeographical bipartite network construction to the identification of biogeographical regions under the form of spatial network communities, the analysis of their interactions, and the identification of clusters of plant species based on the species contribution to the biogeographical regions. First, we identified two sub‐networks that distinguish Mediterranean and temperate biota. Then, we separated eight statistically significant bioregions that present a complex spatial structure. Some of them are spatially well delimited and match with particular geological entities. On the other hand, fuzzy transitions arise between adjacent bioregions that share a common geological setting, but are spread along a climatic gradient. The proposed network approach illustrates the biogeographical structure of the flora in southern France and provides precise insights into the relationships between bioregions. This approach sheds light on ecological drivers shaping the distribution of Mediterranean biota: The interplay between a climatic gradient and geological substrate shapes biodiversity patterns. Finally, this work exemplifies why fragmented distributions are common in the Mediterranean region, isolating groups of species that share a similar eco‐evolutionary history.     

Narrow endemics to Mediterranean islands: Moderate genetic diversity but narrow climatic niche of the ancient,critically endangered Naufraga (Apiaceae)

Narrow endemics constitute the cornerstone of Mediterranean plant diversity. Naufraga balearica (Apiaceae) is a critically endangered, extremely narrow endemic plant from the western Mediterranean island of Majorca. Because the species belongs to a monotypic genus, N. balearica was hypothesized to be a palaeoendemism. Here we conducted phylogenetic dating, population genetic and climatic niche analyses in order to understand the evolutionary history and conservation perspectives of this flagship species. Phylogenetic dating analysis of nuclear and plastid DNA sequences revealed a late Miocene to early Pliocene divergence between Naufraga and its sister genus Apium, supporting the palaeoendemic status of the former. Amplified fragment length polymorphism (AFLP) markers and plastid DNA sequences of the five Naufraga populations revealed moderate genetic diversity. This diversity is in line with that of other palaeoendemisms from western Mediterranean islands, as revealed by a comparison with 22 other narrow endemic species from this region. Despite the fact that all Naufraga populations are located at a maximum distance of 10 km in a straight line, a strikingly strong population differentiation was found for AFLP markers, which is explained by long-term isolation likely related to short-range pollination and dispersal strategies of the species. While the species is not genetically impoverished, species distribution modelling and microclimatic monitoring revealed that narrow ecological requirements underlie the current extreme rarity of Naufraga and may jeopardize its long-term survival. Our results indicate that a multidisciplinary approach provides powerful tools to develop conservation strategies for evolutionarily singular lineages.     

Quantitative prediction of the distribution and abundance of Vaccinium myrtillus with climatic and edaphic factors

Question: Can the distribution and abundance of Vaccinium myrtillus be reasonably predicted with soil nutritional and climatic factors? Location: Forests of France. Methods: We used Braun‐Blanquet abundance/dominance information for Vaccinium myrtillus on 2905 forest sites extracted from the phyto‐ecological database EcoPlant, to characterize the species ecological response to climatic and edaphic factors and to predict its cover/abundance at the national scale. The link between cover/abundance of the species and climatic (65 monthly and annual predictors concerning temperature, precipitation, radiation, potential evapotranspiration, water balance) and edaphic (two predictors: soil pH and C:N ratio) factors was investigated with proportional odds models. We evaluated the quality of our model with 9830 independent relevés extracted from Sophy, a large phytosociological database for France. Results: In France, Vaccinium myrtillus is at the southern limit of its European geographic range and three environmental factors (mean annual temperature, soil pH and C:N ratio) allow prediction of its distribution and abundance in forests with high success rates. The species reveals a preference for colder sites (especially mountains) and nutritionally poor soils (low pH and high C:N ratio). A predictive map of its geographic range reveals that the main potential habitats are mountains and northwestern France. The potential habitats with maximal expected abundance are the Vosges and the Massif central mountains, which are both acidic mountains. Conclusions: Complete niche models including climate and soil nutritional conditions allow an improvement of the spatial prediction of plant species abundance at a broad scale. The use of soil nutritional variables in distribution models further leads to an improvement in the prediction of plant species habitats within their geographical range.     

Niche breadth,environmental landscape,and physical barriers: their importance as determinants of species distributions

Species distributions and their patterns in geographical space have been studied for several decades and explained by theories such as Janzen's, with respect to the nature of dispersal barriers in the Tropics, and Rapoport's, with respect to range size. However, the roles of specific environmental and geographical factors (e.g. ecological niche breadth, geographical barriers, etc.) in shaping species ranges and distributional patterns remain largely unexplored. The present study analyzed predictions from these two theories via analysis of virtual species with respect to biogeographical patterns: virtual species were created across South America, covering all major environments on the continent, and were used to compare effects of niche breadth, environmental availability, connectivity, seasonality, and the presence of known biogeographical barriers (rivers) in shaping species distributions and biodiversity patterns. Geographical ranges varied from narrow to broad, depending on the location of the seed point when comparing species produced with the same niche breadth. Analysis without consideration of seasonality and barriers produced species with broader distributions in the Tropics and narrower distributions in montane and temperate regions of the continent. When seasonality was included, however, broader ranges were concentrated in temperate regions, thus supporting Janzen's idea. Rapoport's rule of broader geographical ranges at higher latitudes was supported only when seasonality and physical barriers were included but not in species with very narrow or very broad niches, suggesting that this ‘rule’ results from interactions among niche breadth, dispersal capabilities, and dispersal barriers. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108 , 241–250.     

Macroecology meets macroevolution: evolutionary niche dynamics in the seaweed Halimeda

Aim Because of their broad distribution in geographical and ecological dimensions, seaweeds (marine macroalgae) offer great potential as models for marine biogeographical inquiry and exploration of the interface between macroecology and macroevolution. This study aims to characterize evolutionary niche dynamics in the common green seaweed genus Halimeda, use the observed insights to gain understanding of the biogeographical history of the genus and predict habitats that can be targeted for the discovery of species of special biogeographical interest. Location Tropical and subtropical coastal waters. Methods The evolutionary history of the genus is characterized using molecular phylogenetics and relaxed molecular clock analysis. Niche modelling is carried out with maximum entropy techniques and uses macroecological data derived from global satellite imagery. Evolutionary niche dynamics are inferred through application of ancestral character state estimation. Results A nearly comprehensive molecular phylogeny of the genus was inferred from a six‐locus dataset. Macroecological niche models showed that species distribution ranges are considerably smaller than their potential ranges. We show strong phylogenetic signal in various macroecological niche features. Main conclusions The evolution of Halimeda is characterized by conservatism for tropical, nutrient‐depleted habitats, yet one section of the genus managed to invade colder habitats multiple times independently. Niche models indicate that the restricted geographical ranges of Halimeda species are not due to habitat unsuitability, strengthening the case for dispersal limitation. Niche models identified hotspots of habitat suitability of Caribbean species in the eastern Pacific Ocean. We propose that these hotspots be targeted for discovery of new species separated from their Caribbean siblings since the Pliocene rise of the Central American Isthmus.     

Crossing barriers in an extremely fragmented system: two case studies in the afro-alpine sky island flora

The flora on the afro-alpine sky islands is renowned for extreme fragmentation, representing a unique natural experiment in biogeography. Here we address the roles of isolation and gene flow, in particular across the narrow Rift Valley (the RV barrier) that cuts through the Ethiopian Highlands (EH), and across the vast low-lying landscape that separates EH from the East African mountains (the EH–EA barrier). We inferred the history of two species with different dispersal mechanisms, but with similar geographic ranges and habitats based on Amplified fragment length polymorphisms (AFLPs). Contrary to our predictions, we found that the populations from opposite sides of the RV barrier were less similar than those from opposite sides of the EH–EA barrier, and that only the supposedly short distance-dispersed species (Trifolium cryptopodium) showed a strong signal of secondary gene flow across the RV barrier. In the wind-dispersed Carduus schimperi, we rather found an evidence for the gene flow between differentiated populations inhabiting different EA mountains. Both species harbored little genetic diversity but considerable genetic rarity in several individual mountains, suggesting long-term isolation and bottlenecks during climatically unfavorable periods. Our genetic data corroborate a division of C. schimperi into three subspecies, but with new delimitation of their ranges, and of T. cryptopodium into two intraspecific taxa. Our findings support the idea that stochasticity may play a major role in shaping extremely fragmented ecosystems such as the afro-alpine. After initial colonization of different mountains, periods of isolation may alternate with unpredictable episodes of intermountain gene flow.     

The historical biogeography of the southern group of the sucker genus Moxostoma (Teleostei: Catostomidae) and the colonization of central Mexico

The historical biogeography of the southern group of Moxostoma Rafinesque, 1820, a genus of Nearctic freshwater fishes belonging to the Catostomidae, along its entire distribution in North America was inferred to: (1) determine the biogeographical events responsible for its current pattern of diversity and distribution; (2) correlate the climatic and geologic history of the region with the biogeographical pattern observed; and (3) trace the colonization route into central Mexico and the western Pacific slope drainages. The sequences of mitochondrial cytochrome b and the third intron of the growth hormone were obtained for the members of the southern group and related species of the Catostomidae. Phylogenetic analyses and relaxed molecular clock analyses were performed to determine the relatedness of the species and to estimate divergence times. To uncover biogeographical patterns, a dispersal–extinction–cladogenesis (DEC) analysis was conducted. The phylogenetic analyses were consistent with the historical hydrographic scenario in the region. The divergence times show that the southern group evolved during the Pliocene–Pleistocene. The DEC analyses showed that vicariance and dispersal played an important role in the current distribution patterns of the lineages in central Mexico, and allow us to trace an independent route of colonization from the northern areas of North America into central Mexico.     

Dispersal limitation and geographical distributions of mammal species

Aim To relate the dispersal limitation of endemic terrestrial mammals in Mexico to species life‐history traits and latitude. Location Mexico. Methods We modelled species ecological niches projected as potential distributions (P) using point occurrence data and 19 environmental variables for 89 endemic mammal species, and compared the areas covered by these ecological niche models with maps of species actual distributions (R) based on minimum convex polygons connecting marginal records based on museum specimens. We correlated body mass, food habits (herbivore, omnivore, insectivore, frugivore/granivore), volant and non‐volant (fossorial, arboreal, terrestrial) habits and mean latitude to the proportion of occupancy of species potential distributional areas (R/P). Results R and P were significantly positively correlated, with an overall average R/P ratio of 0.49. Less than half of the endemics (41 species) had a high occupancy (R/P values ranging from 0.50 to 0.90); a few (four species) showed full occupancy (> 0.90). Body mass and food habits were not correlated with R/P, but latitude showed significant correlations with R/P; volant mammals tended to show higher R/P values than non‐volant mammals. Main conclusions Few species filled most of the spatial extent of their ecological niches. Life‐history traits were generally poor predictors of proportional occupancy of species potential distributions. Endemics occurring at higher latitudes showed higher occupancy, suggesting that abiotic factors are likely to limit their distributions. Conversely, species at lower latitudes showed lower occupancy, suggesting that their distributions are limited by biotic factors and/or by geographical or historical barriers that prevent dispersal. The dispersal abilities of volant compared with non‐volant endemics can explain the higher occupancy in species potential distributions in the former group. These trends provide a baseline for exploring the importance of life‐history traits and abiotic versus biotic factors in limiting species distributions.     

Ecological consequences of contrasting dispersal syndromes in New World Ephedra: higher rates of niche evolution related to dispersal ability

In this study we selected the New World species of Ephedra to understand the ecological consequences of different dispersal syndromes. The twenty‐three species of Ephedra in the New World have a disjunct distribution in North and South American arid and semi‐arid habitats, exhibiting three dispersal syndromes related to dispersal by birds, wind and rodents. Using DNA sequence data we inferred phylogenetic relationships and lineage divergence times, and used these estimates to test different ecological assumptions. Using comparative methods we tested for correlations between dispersal syndromes and a set of ecological variables (niche breadth, niche evolution, distributional ranges and niche position). We found that speciation events in the New World coincided with the expansion of arid habitats in this region. We suggest that the bird dispersal syndrome is related with higher rates of climatic niche evolution for all variables used, including aridity index, mean annual temperature and mean annual precipitation. Distribution ranges were correlated with niche breadth, they were however not significantly different between dispersal syndromes. Species inhabiting the extremely arid regions on niche axes had narrower niche breadths. We conclude that species whose seeds are dispersed by birds have colonized a broader set of habitats and that those with wind and rodent dispersal syndromes might have promoted the colonization of more arid environments.     

Climatic Niche Conservatism and Biogeographical Non-Equilibrium in Eschscholzia californica (Papaveraceae), an Invasive Plant in the Chilean Mediterranean Region

Species climate requirements are useful for predicting their geographic distribution. It is often assumed that the niche requirements for invasive plants are conserved during invasion, especially when the invaded regions share similar climate conditions. California and central Chile have a remarkable degree of convergence in their vegetation structure, and a similar Mediterranean climate. Such similarities make these geographic areas an interesting natural experiment for testing climatic niche dynamics and the equilibrium of invasive species in a new environment. We tested to see if the climatic niche of Eschscholzia californica is conserved in the invaded range (central Chile), and we assessed whether the invasion process has reached a biogeographical equilibrium, i.e., occupy all the suitable geographic locations that have suitable conditions under native niche requirements. We compared the climatic niche in the native and invaded ranges as well as the projected potential geographic distribution in the invaded range. In order to compare climatic niches, we conducted a Principal Component Analysis (PCA) and Species Distribution Models (SDMs), to estimate E. californica''s potential geographic distribution. We also used SDMs to predict altitudinal distribution limits in central Chile. Our results indicated that the climatic niche occupied by E. californica in the invaded range is firmly conserved, occupying a subset of the native climatic niche but leaving a substantial fraction of it unfilled. Comparisons of projected SDMs for central Chile indicate a similarity, yet the projection from native range predicted a larger geographic distribution in central Chile compared to the prediction of the model constructed for central Chile. The projected niche occupancy profile from California predicted a higher mean elevation than that projected from central Chile. We concluded that the invasion process of E. californica in central Chile is consistent with climatic niche conservatism but there is potential for further expansion in Chile.     

Did southern Western Ghats of peninsular India serve as refugia for its endemic biota during the Cretaceous volcanism?

The Western Ghats (WG) of south India, a global biodiversity hotspot, has experienced complex geological history being part of Gondwana landmass and encountered extensive volcanic activity at the end of Cretaceous epoch. It also has a climatically and topographically heterogeneous landscape. Thus, the WG offer a unique setting to explore the influence of ecological and geological processes on the current diversity and distribution of its biota. To this end, three explicit biogeographical scenarios were hypothesized to evaluate the distribution and diversification of wet evergreen species of the WG – (1) southern WG was a refuge for the wet evergreen species during the Cretaceous volcanism, (2) phylogenetic breaks in the species phylogeny would correspond to geographic breaks (i.e., the Palghat gap) in the WG, and (3) species from each of the biogeographic subdivisions within the WG would form distinct clades. These hypotheses were tested on the centipede genus Digitipes from the WG which is known to be an ancient, endemic, and monophyletic group. The Digitipes molecular phylogeny was subjected to divergence date estimation using Bayesian approach, and ancestral areas were reconstructed using parsimony approach for each node in the phylogeny. Ancestral‐area reconstruction suggested 13 independent dispersal events to explain the current distribution of the Digitipes species in the WG. Among these 13 dispersals, two dispersal events were at higher level in the Digitipes phylogeny and were from the southern WG to the central and northern WG independently in the Early Paleocene, after the Cretaceous Volcanism. The remaining 11 dispersal events explained the species’ range expansions of which nine dispersals were from the southern WG to other biogeographic subdivisions in the Eocene‐Miocene in the post‐volcanic periods where species‐level diversifications occurred. Taken together, these results suggest that southern WG might have served as a refuge for Digitipes species during Cretaceous volcanism.     

Gondwanan break-up: legacies of a lost world?

Fierce debate surrounds the history of organisms in the southern hemisphere; did Gondwanan break-up produce ocean barriers that imposed distribution patterns on phylogenies (vicariance)? Or have organisms modified their distributions through trans-oceanic dispersal? Recent advances in biogeographical theory suggest that the current focus on vicariance versus dispersal is too narrow because it ignores 'geodispersal' (i.e. expansion of species into areas when geographical barriers disappear), extinction and sampling errors. Geodispersal produces multiple, conflicting vicariance patterns, and extinction and sampling errors destroy vicariance patterns. This perspective suggests that it is more difficult to detect vicariance than trans-oceanic dispersal and that specialized methods must be applied if an unbiased understanding of southern hemisphere biogeography is to be achieved.