Vicariance

The Austral biota reveals many links between Australasia and South America that have challenged biogeographers for many years. Nothofagus, the Southern Beech, is probably the classical example. With the general acceptance of continental drift, the break-up of Gondwana is regarded as primarily responsible for many disjunct patterns expressed in the Southern Hemisphere biota. Vicariance biogeography is the principal tool used to investigate biogeographic patterns of extant plant groups, resulting in areagrams or general area cladograms. These are often at odds with current geological knowledge, and on this basis, alternative hypotheses of area relationships and geological history have, therefore, been suggested. One such areagram was recently advocated by Linder & Crisp (1995) in a biogeographic analysis of Nothofagus. Three explanations, often in combination, account for incongruence: long-distance dispersals, extinctions, and erroneous geological models. All of these parameters ought to be considered in the analysis. Here we report the result of a historical biogeographic analysis of Nothofagus where we compare the reconciled trees between a well-supported Nothofagus phylogeny and two geological hypotheses: (I) the current view of Gondwana break-up. and (2) the areagram by Linder & Crisp. Our analysis makes use of extant and extinct taxa, as well as the assumption of long-distance dispersals as defined by maximized vicariance. Our results show that Nothofagus existed prior to the break-up of Gondwana and, most importantly, its present distribution supports, and is dependent upon, the traditional break-up sequence of East Gondwana. compatible with three vicariance events. The areagram, conceived as an alternative geological hypothesis, presents a more parsimonious solution, but fails to explain numerous past distributions in areas such as Antarctica, South America, and Tasmania. We therefore recommend a conservative approach to use (general) areagrams in historical biogrography.

Dispersals versus vicariance events and the presence of subgenus Brassospora in New Caledonia are two riddles of Nothofagus biogeography, a genus also distributed in New Guinea, New Zealand, South America, Southeast Australia, and Tasmania. Within a cladistic framework using the software COMPONENT 2.0, we demonstrate that most parsimonious area cladograms (areagrams) sensu cladistic biogeography need not always be the most plausible explanation nor reflect alternative geological hypotheses. The most parsimonious Nothofagus history sensu historical biogeography is reconstructed where a
minimum of dispersed taxa is hypothesized and vicariance events are identified. A fully resolved well-established Nothofagus phylogeny was reconciled with three geological hypotheses (geograms) of East Gondwana break-up: (a) the conventional view, (b) an Australian–New Caledonian relationship, and (c) a biotic inter-change between New Guinea and New Caledonia. Fossils determined to subgenus were optimized to the predicted lineages in the reconciled tree. Due to extensive extinctions, a maximum of three vicariance events are inferred, all being basal in the subgenera, an indication of subgeneric diversification prior to the break-up of Gondwana. Two taxa, N. gunnii and N. menziesii, are hypothesized as being long-distance dispersed. The most parsimonious solution suggests a close relationship between New Guinea and New Caledonia, supporting a Brassospora colonization route, but this hypothesis fails to predict numerous extinct lineages observed in the fossil record and thus must be rejected. The traditional break-up sequence of Gondwana is not the most parsimonious solution, indicating one incongruent node, but causes no overall incongruence with the fossil record. Considering all parameters, the occurrence of Brassospora in New Caledonia is most parsimoniously explained as a single colonization event from New Zealand where the subgenus subsequently went extinct in the Pliocene.

The evolutionary centre of origin of Nothofagus (Nothofagaceae) remains an open question. Competing hypotheses suggest either a South American or Australasian source area for Nothofagus. Antarctica, once part of Gondwana and densely vegetated in the Cretaceous, was certainly important for the diversification of the genus but cannot be included in current modelling due to its lack of extant species. By using Bremer’s (1992), Ronquist’s (1994) and Hausdorf’s (1998) methods, all based on cladistic philosophy, analyses of the modern areas of endemism being part of the ancestral area of Nothofagus were undertaken. Southern South America was distinctly identified as the likely ancestral area by Bremer’s and Hausdorf’s methods. This result is supported by the current fossil record. Ronquist’s method was not decisive and yielded ambiguous results, suggesting a larger, combined ancestral area. These results do not favour Australasia, or parts thereof, being an important area for Nothofagus origin. Bremer’s and Hausdorf’s methods identified New Zealand as the second most plausible source area, a result partly supported by the fossil record.

The distributions of 51 non-human primate species are used for Parsimony Analysis of Endemicity (PAE) to determine the relationships among 14 interfluvial regions in the Amazon basin, South America. Two most parsimonious cladograms were found. The strict consensus tree of these cladograms suggests an early separation between Lower Amazonia (eastern) and Upper Amazonia (western). The major clusters of interfluvial regions identified in the PAE cladogram are congruent with the areas of endemism delimited for birds. When interfluvial regions are converted into avian areas of endemism, the PAE cladogram is congruent with one of the two general areas cladograms suggested for Amazonia based on phylogenies of several clades of forest birds. Our analysis suggests that PAE can be used as a tool to objectively identify areas of endemism at an intra-continental scale as well as to make historical inferences. However, the value of a PAE cladogram in this latter application should be always evaluated by congruence with area cladograms built upon cladistic biogeography procedures.

Abstract: Genetic variation within species—a priority for biodiversity conservation—is influenced by natural selection, demography, and stochastic events such as genetic drift. We evaluated the role of these factors in 14 codistributed species of reptiles and amphibians on the Indonesian island of Halmahera by testing whether their molecular variation was correlated with geographic distance, ecology, riverine barriers, or Halmahera's paleoisland precursors. We found support for isolation by distance effects in four species. Two of these four were also significantly affected either by rivers or by ecology. A fifth species was significantly affected by ecology and a sixth was significantly affected by Halmahera's paleoislands. [Correction added after publication 9 December 2009: the previous sentence was edited for clarity.] These findings—the most comprehensive survey of multispecies genetic variation on Halmahera to date—bode well for the efficacy of the recently established Aketajawe-Lolobata National Park in conserving a substantial component of vertebrate genetic variation on this island. Future success of conservation efforts will depend crucially, of course, on funding for and enforcement of conservation management of this park.Resumen: La variación genética intraespecífica—una prioridad para la biología de la conservación—es influida por la selección natural, la demografía y eventos estocásticos como la deriva génica. Evaluamos el papel de estos factores en 14 especies de anfibios y reptiles codistribuidas en la Isla Halmera, Indonesia probando sí la variación molecular se correlaciona con la distancia geográfica, la ecología, las barreras ribereñas o los precursores paleoinsulares de Halmahera. Encontramos soporte para los efectos del aislamiento por distancia en cuatro especies. La estructura genética de dos especies fue afectada por la ecología, una especie fue afectada significativamente por los ríos, y una especie fue afectada por las paleoislas de Halmahera. Estos hallazgos—el muestreo más integral de la variación genética de especies de Halmahera a la fecha—son promisorios para la eficacia del recién establecido Parque Nacional Aketajawe-Lolobata en la conservación de un componente sustancial de la variación genética de vertebrados en esta isla. Por supuesto que el éxito futuro de los esfuerzos de conservación dependerá crucialmente del financiamiento para y la puesta en práctica de la gestión de conservación de este parque.Resumen: La variación genética intraespecífica—una prioridad para la biología de la conservación—es influida por la selección natural, la demografía y eventos estocásticos como la deriva génica. Evaluamos el papel de estos factores en 14 especies de anfibios y reptiles codistribuidas en la Isla Halmera, Indonesia probando sí la variación molecular se correlaciona con la distancia geográfica, la ecología, las barreras ribereñas o los precursores paleoinsulares de Halmahera. Encontramos soporte para los efectos del aislamiento por distancia en cuatro especies. La estructura genética de dos especies fue afectada por la ecología, una especie fue afectada significativamente por los ríos, y una especie fue afectada por las paleoislas de Halmahera. Estos hallazgos—el muestreo más integral de la variación genética de especies de Halmahera a la fecha—son promisorios para la eficacia del recién establecido Parque Nacional Aketajawe-Lolobata en la conservación de un componente sustancial de la variación genética de vertebrados en esta isla. Por supuesto que el éxito futuro de los esfuerzos de conservación dependerá crucialmente del financiamiento para y la puesta en práctica de la gestión de conservación de este parque.

The Red Sea has had a profound biogeographic effect on organisms with Afro-Asian distributions, resulting in complex patterns of admixture on the Arabian Peninsula. We investigate the phylogenetic affinities of a monitor lizard (Varanus yemenensis) restricted to the southwestern Arabian Peninsula by sequencing all African monitor species and several Asian monitor species for the mitochondrial gene ND2 and the nuclear marker RAG-1. We find evidence that V. yemenensis is of African origin, being most closely related to the white-throat monitor, V. albigularis, an African species complex distributed from the Horn of Africa to southern Africa. Using divergence-dating analyses, we investigate several biogeographic hypotheses to infer the likely mechanism of colonization of the Arabian Peninsula by this species. Our results reveal that both dispersal across a southern land bridge and overwater dispersal are potential explanations. The patterns observed in V. yemenensis are contrasted with other taxa having similar Afro-Arabian disjunct distributions to better understand the complex biogeographic history of this region.► Varanus yemenensis is a recently described monitor lizard restricted to the southwestern Arabian Peninsula. ► Based on mitochondrial and nuclear data, V. yemenensis is determined to be of African origin, rather than Asian origin. ► Varanus yemenesis is most closely related to Varanus albigularis microstictus. ► Divergence dating reveals a late Miocene to early Pliocene split. ► Both an overwater dispersal event or southern land bridge dispersal can explain the original colonization event.

A new subspecies of Heraclides androgeus (Lepidoptera: Papilionidae) and its biogeographical aspects. Heraclides androgeus epidaurus was described and illustrated by Godman & Salvin in 1890 based on specimens obtained in Veracruz, indicating that their distribution encompassed both the Pacific and Atlantic sides of Mexico. Later authors commented that there were morphological differences between the male wings from both populations. We analyzed, described and nominated Heraclides androgeus reyesorum ssp. nov. Vargas, Llorente…

We used inferences of phylogeographical structure and estimates of divergence times for three species of gophersnakes (Colubridae: Pituophis) distributed across the Mexican Transition Zone (MTZ) to evaluate the postulated association of three Neogene geological events (marine seaway inundation of the
Isthmus of Tehuantepec, formation of the Transvolcanic Belt across central Mexico, and secondary uplifting of the Sierra Madre Occidental) and of Pleistocene climate change with inter- and intraspecific diversification.

ABSTRACT AimThe aim of this study was to understand the biogeography of Brachygastra. As the spatial component of evolution is of fundamental importance to understanding the processes shaping the evolution of taxa, the known geological history of the Neotropical region was used together with the current phylogeny and distribution of species to investigate questions concerning the biogeography of Brachygastra: the ancestral ranges of Brachygastra species; their areal relationships and their congruence with previously published hypotheses; the possible associated vicariance events and the influence of land bridges between North and South America, and the split between the Amazon and Atlantic forests.LocationNeotropical region, from Mexico to central Argentina and southern USA.Methods Statistical dispersal–vicariance analysis (S-DIVA) was used to reconstruct the possible ancestral ranges of Brachygastra species based on their phylogeny (divided into three groups, lecheguana, scuttelaris and smithii). A Brooks parsimony analysis (BPA) and component analysis were performed to reconstruct the areal relationships of these species within the Neotropics.ResultsS-DIVA suggested a widespread, South American ancestral region for Brachygastra. The ancestral B. azteca probably reached the Nearctic before a posterior vicariance event separated it from the species groups ((lecheguana (scutellaris + smithii))), that stayed in the Atlantic forest. The ancestral (scutellaris + smithii groups) possibly reached the Amazon by dispersal, and the subsequent vicariance event splitting the Atlantic forest and Amazon separated the groups into scutellaris in the Atlantic forest and smithii in the Amazon. BPA and component analyses suggested that the Nearctic was a sister area to other regions, the Andes and Mesoamerica was a sister area to the Neotropical regions and the Amazon was closely related to the Atlantic forest.Main conclusionsThe phylogeny and distribution of Brachygastra suggest the influence of a land bridge between the Northern and Southern Hemispheres affecting the cladogenesis of B. azteca and the importance of the formation of the two blocks of forests in South America to the cladogenesis of the main groups of Brachygastra. Future comparisons between the distribution patterns of other taxa should enable a more precise identification of the possible events and outcomes, adding robustness to the hypothesized areal relationships.

Genetic structure within marine species may be driven by local adaptation to their environment, or alternatively by historical processes, such as geographic isolation. The gulfs and seas bordering the Arabian Peninsula offer an ideal setting to examine connectivity patterns in coral reef fishes with respect to environmental gradients and vicariance. The Red Sea is characterized by a unique marine fauna, historical periods of desiccation and isolation, as well as environmental gradients in salinity, temperature , and primary productivity that vary both by latitude and by season. The adjacent Arabian Sea is characterized by a sharper environmental gradient, ranging from extensive coral cover and warm temperatures in the southwest, to sparse coral cover, cooler temperatures, and seasonal upwelling in the northeast. Reef fish, however, are not confined to these seas, with some Red Sea fishes extending varying distances into the northern Arabian Sea, while their pelagic larvae are presumably capable of much greater dispersal. These species must therefore cope with a diversity of conditions that invoke the possibility of steep clines in natural selection. Here, we test for genetic structure in two widespread reef fish species (a butterflyfish and surgeonfish) and eight range-restricted butterflyfishes across the Red Sea and Arabian Sea using genome-wide single nucleotide polymorphisms. We performed multiple matrix regression with randomization analyses on genetic distances for all species, as well as reconstructed scenarios for population subdivision in the species with signatures of isolation. We found that (a) widespread species displayed more genetic subdivision than regional endemics and (b) this genetic structure was not correlated with contemporary environmental parameters but instead may reflect historical events. We propose that the endemic species may be adapted to a diversity of local conditions, but the widespread species are instead subject to ecological filtering where different combinations of genotypes persist under divergent ecological regimes.

Vicariance is thought to have played a major role in the evolution of modern parrots. However, as the relationships especially of the African taxa remained mostly unresolved, it has been difficult to draw firm conclusions about the roles of dispersal and vicariance. Our analyses using the broadest taxon sampling of old world parrots ever based on 3219 bp of three nuclear genes revealed well-resolved and congruent phylogenetic hypotheses. Agapornis of Africa and Madagascar was found to be the sister group to Loriculus of Australasia and Indo-Malayasia and together they clustered with the Australasian Loriinae, Cyclo- psittacini and Melopsittacus. Poicephalus and Psittacus from mainland Africa formed the sister group of the Neotropical Arini and Coracopsis from Madagascar and adjacent islands may be the closest relative of Psittrichas from New Guinea. These biogeographic relationships are best explained by independent col- onization of the African continent via trans-oceanic dispersal...