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In The Monkey’s Voyage, I focused on the issue of disjunct distributions, and, in particular, on the burgeoning support from molecular-dating studies for long-distance dispersal over vicariance as the most reasonable explanation for many (but by no means all) distributions broken up by oceans. Michael Heads’ assessment of the book is founded on his long-standing belief, following Croizat, that long-distance dispersal is an insignificant process and, therefore, that disjunctions are virtually always attributable to vicariance. In holding to these notions, Heads offered a series of unsound arguments. In particular, to preserve an ‘all-vicariance’ perspective, he presented a distorted view of the nature of long-distance dispersal, misrepresented current applications of fossil calibrations in molecular-dating studies, ignored methodological biases in such studies that often favour vicariance hypotheses, repeatedly invoked irrelevant geological reconstructions, and, most strikingly, showed a cavalier approach to evolutionary timelines by pushing the origins of many groups back to unreasonably ancient ages. The result was a succession of implausible histories for particular taxa and areas, including the notions that the Hawaiian biota is almost entirely derived from ancient (often Mesozoic) central Pacific metapopulations, that the disjunctions of extremely mobile organisms such as ducks rarely, if ever, result from long-distance dispersal, and that primates were widespread 120 million years before their first appearance in the fossil record. In contrast to Heads’ perspective, a central message of The Monkey’s Voyage is that explanations for disjunct distributions should be evaluated on the basis of diverse kinds of evidence, without strong a priori assumptions about the relative likelihoods of long-distance dispersal and vicariance.
In the present paper, we develop a new biogeographic model for the biota of the Southwest Pacific, using 76 published phylogenies for a range of island endemics or near-endemic organisms. These phylogenies were converted to areagrams by substituting distributions for taxa. Paralogy-free subtrees (3-item statements) were derived from these areagrams and used as input data into LisBeth that uses compatibility analysis and an exhaustive branch and bound algorithm to produce optimal trees. A general areagram is derived from all three-item statements common to the optimal trees. The results of the analysis show that the Melanesian Rift is not a natural biogeographic area; the islands of the Southwest Pacific are more closely related to each other than they are to Australia; and New Caledonia has had a long history of biological isolation. There is support for a general period of mobilism during the mid-Cenozoic when the biota as a whole expanded its range in response to regional uplift. By comparing the general areagram with what is known about the tectonic development of the region, it is possible to both calibrate the nodes of the areagram, and to identify points of conflict between the geological and biological data.
Agaricoid fungi from Patagonia have been vastly studied taxonomically since 1887, and more recently ecologically. We found five generalised tracks and three nodes for a selection of nine ectomycorrhizal and nine saprophytic species. Two areas are supernodes, complex areas supported by many nodes. One of these supernodes could be a result of a lack of sampling in the Strait of Magellan area. The other could imply a biotic radiation and a differential tolerance to more arid climate conditions in the Andes mountain chain around 44.3°S, 71.5°W. Two important areas to focus future sampling of agaricoid fungi are suggested. Generalised tracks obtained match those found for weevils (Coleoptera: Curculionidae) and oribatid mites (Acari: Oribatida) distributed along the Magellanic Forest and Magellanic Moorland provinces of the Andean region. Overlap of generalised tracks among unrelated taxa supports the idea that common processes might have caused the observed patterns. The most significant and undeniable fact is that fungal species present ecological traits that can be vital for studying geological events that have marked the biotic development.
A vicariance model is presented for the origin of Macaronesian endemics and their allopatric American relatives. Trans-Atlantic relationships are identified for 21 taxa in which an endemic Macaronesian clade either has a sister group in the New World or is part of a larger monophyletic group that includes representatives in the New World. Historical implications of this pattern are discussed in relation to current tectonic and geological models for the Central Atlantic and the Macaronesian Islands. The proposed vicariance model identifies a local origin for the Macaronesian endemics from ancestral distributions that already encompassed ancestral Macaronesia and parts of the New and Old World before formation of the Atlantic. The present-day existence of Macaronesian endemics is attributed to sequential colonisation of newly formed islands within the Atlantic from Mesozoic time.
Evolutionary biogeography aims to provide a hierarchical system of biotic regionalisation for areas of the Earth that correspond to natural areas related by their common evolutionary history. In this context, the central Pampean Ranges of Argentina, formed by the mountain systems of Córdoba and San Luis, are immersed in the Chacoan dominion; however, higher-altitude environments of these mountains, namely highland grasslands and tabaquillo forests, have relationships with the Andean region and other Neotropical areas that are different from the Chacoan dominion, which would indicate that the current classification would not be natural. To clarify their biogeographic relationships, a track analysis of the distribution of the biota of vertebrates and vascular plants of the highland grasslands and tabaquillo forests of central Pampean Argentinian Ranges was conducted. The obtained distributional patterns suggest that the area under study has diverse geobiotic origins, both Andean and Neotropical, indicating that, in this area, an interaction of biota with different evolutionary origins occurs; so, its status as a biogeographic province is proposed, belonging to the South American transition zone.
A transition zone shows the overlap between two or more regions and represents an event of biotic hybridisation, where different cenocrons assembled as a result of historical and ecological processes. The Mexican transition zone, the area where the Nearctic and Neotropical regions overlap, includes the following five biogeographical provinces: Sierra Madre Occidental, Sierra Madre Oriental, Sierra Madre del Sur, Transmexican Volcanic Belt and Chiapas Highlands. Within this transition zone, the following five cenocrons have already been recognised: Paleoamerican, Mexican Plateau, Mountain Mesoamerican, Nearctic and Typical Neotropical. We undertook three cladistic biogeographic analyses on the basis of 49 cladograms of terrestrial taxa, partitioning them into three time-slices, namely, Miocene (Mountain Mesoamerican cenocron), Pliocene (Mountain Mesoamerican plus Nearctic cenocrons) and Pleistocene (Mountain Mesoamerican, Nearctic and Typical Neotropical cenocrons). For the Miocene time-slice, we observed a close relationship of the Transmexican Volcanic Belt with the Neotropical region, whereas, for the Pliocene and Pleistocene time-slices, the closest relationship of the Transmexican Volcanic Belt was with the Nearctic region. We conclude that the Transmexican Volcanic Belt may have played a different role according to the cenocron analysed, and that the Mexican transition zone differs in its delimitation depending on the taxa analysed, strengthening the idea that it is a complex area.
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