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Panbiogeographic analysis is now used by many authors, but it has been criticised in recent reviews, with some critics even suggesting that studies using the method should not be accepted for publication. The critics have argued that panbiogeography is creationist, that it rejects dispersal, that its analyses are disingenuous, and that it deliberately ignores or misrepresents key evidence. These claims are examined here, and are all shown to be without foundation. The distributions of the molecular clades of ratites have not been mapped before, and they are considered here in some more detail as a case study illustrating panbiogeographic methodology.
Uncertainty in identifying Allocasuarina shrubs of the North Coast botanical region of New South Wales and south-eastern Queensland prompted investigation of species limits using morphological and cytological data. PATN analysis using 36 morphometric characters, seedling morphology and cytogenetic analysis supported the existing circumscription of A. defungens and A. simulans. Trees of A. littoralis were observed throughout the study area and the distinct morphology of the diploid and polyploid forms is noted. Further work is required to establish whether these differences are consistent over the full range of the species. Shrubby plants of A. sect. Cylindropitys, other than the above species, growing along the NSW North Coast are currently known by several names, including A. defungens × A. littoralis. These plants were found to be morphologically most similar to A. emuina and A. thalassoscopica from south-eastern Queensland and to have similar phenotypes. Allocasuarina thalassoscopica is recircumscribed on morphological characters to encompass these shrubby plants in New South Wales and A. emuina and A. thalassoscopica from south-eastern Queensland. A key is provided for identification of plants of A. sect. Cylindropitys. Counts of chromosomes found that recircumscribed A. thalassoscopica is tetraploid and A. defungens is triploid at Nabiac but tetraploid at Khappinghat Nature Reserve. The results of the present study are consistent with a hypothesis of parallel evolution, which is possibly due to edaphic factors and requires further study.
This article reviews the methods of biogeographic analysis in current use, as summarised by Alan de Queiroz, 2014 (The Monkey’s Voyage, Basic Books, New York). The methods rely on molecular clock dates (the weakest part of molecular research) rather than analysis of the distributions of clades defined in phylogenies (the strongest part of the research). One of the main findings of the molecular work is the unexpected, high levels of geographic structure in clades, especially allopatry. The modern synthesis and many molecular clock studies suggest that allopatric speciation is caused by founder dispersal, whereas panbiogeography attributes it to vicariance. De Queiroz and many modern studies have accepted that panbiogeography ignores critical evidence, and that vicariance theory was dominant in the 1970s–1990s, but has since declined. Closer examination shows that these claims are incorrect. Other popular misconceptions include the ideas that fossils and fossil-calibrated molecular clocks provide maximum possible ages of clades, that vicariance theory rejects the fossil record and molecular clock dates, that DNA sequences ‘reveal’ long-distance dispersal, that distribution is chaotic, and that chance dispersal can generate repeated patterns. The conclusions of modern island biogeography, as discussed in detail by de Queiroz, are reviewed here for the following islands: São Tomé and Príncipe in the Gulf of Guinea, Madagascar, the Seychelles, New Zealand, the Chatham Islands off mainland New Zealand, New Caledonia, Norfolk Island, the Hawaiian Islands, the Falkland Islands and Fernando de Noronha off Brazil. Biogeographic analyses of particular groups are illustrated here with respect to ratite birds and primates. Finally, modern methods of ancestral-area analysis are reviewed. These make the unjustified assumption that the location of a basal paraphyletic grade represents a centre of origin.
The genus Melicytus (Violaceae), formerly regarded as comprising a single species, M. dentatus, in mainland Australia and Tasmania, is revised. We recognise M. dentatus, M. angustifolius subsp. angustifolius and M. angustifolius subsp. divaricatus following detailed herbarium and field studies, and morphological and molecular analyses. Full nomenclature is provided, and each species and subspecies is illustrated and mapped.