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The Miocene convergence of the Sunda shelf, Sahul shelf and Wallacea facilitated the exchange of previously isolated floras across the Sunda–Sahul Convergence Zone (SSCZ). The SSCZ is a hotspot of biogeographical research; however, phytogeographical patterns across the region remain poorly understood. We conducted multivariate analysis on a comprehensive species checklist of SSCZ vascular plants to quantify the extent of exchange, characterize phytogeographical patterns and investigate their abiotic drivers. We found that Lydekker's and Wallace's Lines are not reflected in floristic composition at any taxonomic level, with 46% of genera distributed across these biogeographical lines. In contrast, environment is significantly correlated with floristic composition, with annual rainfall and seasonality being the strongest correlates. Mainland Asia, Borneo, the Philippines, New Guinea and Australia were major routes of exchange throughout the Cenozoic, possibly because these areas have been persistent landmasses throughout the entire period of convergence. We conclude that Sunda–Sahul floristic exchange has substantially influenced the assembly of the regional flora and that modern phytogeographical patterns have been influenced more by environmental variables and available landmass (i.e. establishment conditions) than by putative barriers to movement such as Wallace's and Lydekker's Lines (i.e. vagility). [ABSTRACT FROM AUTHOR]

Based on a comprehensive literature survey, we determined the sources of the terrestrial vertebrate species on Christmas Island, asking where they originated relative to Wallace's Line (the southern end of the divide lies 1100 km to the east, where the Lombok Strait adjoins the eastern Indian Ocean). The two bats, Pipistrellus murrayi and Pteropus natalis , are from the west. Concerning the endemic and 'resident' bird species, one is from the west (Collocalia natalis), four are from the east (Accipiter fasciatus , Egretta novaehollandiae , Falco cenchroides and Ninox natalis) and the other 15 are ambiguous or indeterminate. Most of the land-locked species are also from the east: rodents Rattus macleari and Rattus nativitatis , and squamates Cryptoblepharus egeriae , Emoia nativitatis and Lepidodactylus listeria. Additionally, two have westerly origins (Crocidura trichura and Cyrtodactylus sadleiri), one is ambiguous (Emoia atrocostata) and another is unknown (Ramphotyphlops exocoeti). West-directed surface currents that flow across the eastern Indian Ocean towards Christmas Island would have facilitated most of the land-animal colonizations. We therefore suggest that Wallace's Line be redrawn such that the landmass is placed on the Australasian side of this fundamental biogeographical boundary. [ABSTRACT FROM AUTHOR]

Archdukes, barons, counts, dukes and marquises are forest-dwelling butterflies found in mainland Asia and most islands of the Indo-Australian archipelago west of Wallace's Line, with only a few species occurring as far east as the Bismarck Archipelago. This pattern is unusual among butterfly groups of the region, which often present more widespread geographical ranges bearing little signature of Lydekker's and Wallace's Lines. Using a molecular multimarker matrix, we infer the first dated phylogeny for this clade and estimate its biogeographical history. We recover the Oriental genus Euthalia as polyphyletic, although other genera are monophyletic. The clade originated in continental Indomalaya in the late Oligocene ~24 Mya, when the Indo-Australian archipelago was at one of the most dynamic stages of its orogeny. Multiple independent colonization events towards the Lesser Sunda Islands, Moluccas, Australia and New Guinea suggest the relative permeability of Lydekker's and Wallace's Lines to these butterflies. Colonization of Melanesia took place twice, probably before the recent formation of Sulawesi. The study of Indo-Australian Adoliadini provides additional evidence that biogeographical barriers long thought to prevent exchange between the Asian and Australian biotas are, in fact, permeable especially to vagile insect lineages in the region. [ABSTRACT FROM AUTHOR]

Disjunct geographical ranges are striking features, often difficult to comprehend without an evolutionary framework. The butterfly genus Charaxes Ochsenheimer, 1816 presents such a fragmented distribution, being distributed from the Mediterranean region, throughout Africa and into the Indo-Australian archipelago, albeit being absent from the northeastern Arabian Peninsula to eastern Pakistan. Among Asian Charaxes, the black rajah Charaxes solon (Fabricius, 1793) represents a unique Asian species in an African clade. Morphological evidence suggests broad phenotypic plasticity across the species range, from India to Wallacea, as exemplified in numerous subspecies placed in four morphological groups. To test species limit hypotheses in this lineage, we generate data for five loci from museum specimens. We include multiple subspecies and all four morphological groups. We recover four genetic clades also supported by geography, morphology and multispecies coalescent analyses. Based on these results, we recognize Charaxes echo Butler, 1867 stat. rev. Charaxes hannibal Butler, 1869 stat. rev. and Charaxes lampedo (Hübner, [1823]) stat. rev. as valid species. Divergence time estimates indicate an origin of this complex in the late Miocene and subsequent diversification in the early Pliocene. Speciation was probably triggered by the late assembly of the Indo-Australian archipelago and by climatic and bathymetric fluctuations in the Miocene. [ABSTRACT FROM AUTHOR]

Whether the impact of a specific barrier type is consistent across multiple levels of biodiversity (e.g. populations vs. species) and whether phylogeographical and biogeographical patterns can be structured by the same isolation force have rarely been investigated in evolutionary studies. We investigated the effect of oceanic barriers on genetic divergence among Xylotrupes beetles from the Indo-Australian Archipelago. We found that zoogeographical regions isolated by oceanic trenches were characterized by endemic lineages/species complexes. Dispersal was rare between regions. We further found that populations separated by oceanic barriers were associated with a significantly higher population subdivision compared with populations not separated by oceanic barriers. We did not, however, detect an increased rate of speciation associated with oceanic barriers, implying that the impact of oceanic barriers on population- vs. species-level genetic divergence may have differed. Although our simulation results suggest limited statistical power for detecting concerted divergence, we hypothesize that the concerted action of a barrier at different levels of biodiversity may depend on the mediating effects of the diversification process itself, such as the duration of speciation and the time required for sympatric species to evolve coexistence. [ABSTRACT FROM AUTHOR]

The characterization of species limits and diversification patterns across the geographically complex Indo-Pacific region has presented biogeographers and evolutionary biologists with great challenges. In the present study, we investigated the brown cuckoo dove ( Macropygia amboinensis s.l.) species complex, whose distribution spans this entire region. We analyzed whether bioacoustic data are congruent with previous plumage-based classifications and whether glacial land bridges have impacted bioacoustic diversification in these doves. Using an unusually large vocal dataset of > 300 recordings from over 30 islands and 24 taxa, we analyzed 29 bioacoustic frequency and temporal parameters and tested for a correlation between geographical and bioacoustic distances. We found a weak correlation between geographical and bioacoustic distances. We identified numerous lineages that are bioacoustically distinct and proposed their elevation to the species level, leading to a doubling of the number of species in this complex and indicating a high proportion of cryptic species-level diversity that has previously gone unrecognized. [ABSTRACT FROM AUTHOR]

Wallacean island populations of two Vespertilioninae bats,Myotis muricolaandScotophilus kuhlii, which have similar geographical ranges, showed marked contrast in the amount and pattern of genetic variation. Within islands, genetic variation was on average much higher inM. muricolabut declined from west to east, whereas all populations ofS. kuhliihad uniformly low levels of genetic variation by mammalian standards.S. kuhliishowed little genetic differentiation between islands and estimates of gene flow were substantial whereas island populations ofM. muricoladiffered markedly and there was a strong isolation-by-distance effect associated with the extent of the sea crossing between islands. Furthermore, the lower mean heterozygosity and small genetic distances between eastern island populations ofM. muricolais evidence that there has been a bottleneck associated with the colonization of this area. The attenuation of genetic diversity to the east is also seen in some other mammalian species and may indicate limits to dispersal and have implications for species management. The patterns of variability inS. kuhliimay be a consequence of its strong dispersal capacity and close association with human activity, which, together with other factors, suggest a panmictic population. © 2004 The Linnean Society of London,Biological Journal of the Linnean Society, 2004,83, 421–431. [ABSTRACT FROM AUTHOR]

Morphological and genetic analyses of Eonycteris spelaea from 15 islands along the Banda Arc, from Sumatra to Timor and including Kalimantan and Sulawesi, revealed considerable divergence between islands and geographical patterning. On the basis of both morphology and genetics, the populations on the large islands of Greater Sunda (Sumatra, Java, Kalimantan and Sulawesi) are generally distinct from one another and from those on the islands in Nusa Tenggara (Lombok to Timor), which form a more cohesive cluster. These differences may be the result of the Nusa Tenggara populations having been colonized more recently than those on the Greater Sunda, and probably from a single source. All biological measures of the relationships between island populations are positively associated with the extent of the sea-crossing between them, indicating the sea is an important barrier to movement. Multivariate analyses show the presence of a marked trend for body size to increase from west to east. However, individuals from Kalimantan are not consistent with this trend, being smaller than predicted, and on the two outer Banda Arc islands of Sumba and Timor animals are a little larger than predicted from the longitudinal trend. These differences could be due to the relative isolation of these populations or differing environmental conditions. There is also a negative relationship between body size and island area, but this is confounded by the longitudinal trend. No significant longitudinal trends in the genetic data were detected and the trend in body size may be an adaptive response to an environmental cline that is known to occur in this region. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79, 511–522. [ABSTRACT FROM AUTHOR]