Australian rainforests: patterns and change

Webb, L. J.; Tracey, J. G.

doi:10.1007/978-94-009-8629-9_22

Cited by 186 publications

(181 citation statements)

References 48 publications

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“…For instance, the proportion of species with wind-dispersed propagules in our sample was 21%, with representatives from 12 families. By contrast, the available data shows that wind dispersal is rare in lowland rain-forest trees of North Queensland (Irvine & Armstrong 1990, Webb & Tracey 1981 and Costa Rica (Levey et al 1994), although it does reach 16% for the large trees of Barro Colorado Island moist forest (Gentry 1982). The relatively high proportion of wind dispersal in New Caledonia may be related to nutrient-deficient soils and the low diversity of vertebrates.…”

Section: Discussionmentioning

confidence: 99%

Reproductive traits of tropical rain-forest trees in New Caledonia

2003

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Reproductive traits of 123 species of rain-forest tree from ultramafic regions of New Caledonia were assessed, mainly from herbarium specimens. Most species had extremely small, simple, pale-coloured flowers that are probably mainly pollinated by small insects, but not including bees. The seeds of most species were considered to be bird dispersed. However, wind is also important for pollination and seed dispersal. The phenological trend was for an increase in the number of species flowering and fruiting around the end of the warm dry season/start of the hot wet season, followed by a decline at the end of the wet season, and lower proportions during the cooler season. Seed size was significantly correlated with fruit size. Other correlations, between flower size and fruit size, and between seed size and seed number, were significant using species as independent observations, but did not hold following phylogenetic correction. Compared with non-dioecious species, dioecious species had significantly larger seeds, and a greater proportion of species with biotic dispersal, abiotic pollination and solitary (female) flowers. The long-term persistence of at least the larger-seeded tree species in New Caledonia is precarious, since the endemic giant pigeon, Ducula goliath, is probably their principal effective disperser, and this species is in decline.

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Section: Discussionmentioning

confidence: 99%

Reproductive traits of tropical rain-forest trees in New Caledonia

2003

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“…The climatic oscillations of the Late Quaternary, with greatly reduced temperature and rainfall at the Last Glacial Maximum ( LGM, 18 thousand years before present, 18 Kya), followed by a permissive cool-wet phase in the Early Holocene (8-7.5 Kya) and then a warm-wet phase (5-3.5 Kya) prior to the establishment of current conditions ( Kershaw & Nix 1988), had profound effects on the distribution of rainforests and of rainforest-dependent fauna in the Wet Tropics ( Williams & Pearson 1997;Graham et al 2006). Retraction of Wet Tropics rainforest to refugia during restrictive climates, the LGM in particular, is supported by evidence from palynology ( Kershaw 1994;Kershaw et al 2005), phytogeography ( Webb & Tracey 1981) and also by spatial modelling of rainforests under varying climates ( Nix 1991;Graham et al 2006;Hilbert et al 2007;VanDerWal et al 2008). Predicted Late Quaternary refugia (figure 1b) vary in spatial scale and connectivity, with a major disjunction centred on the Black Mountain Corridor ( BMC) that separates multiple small refugia in the north from a major refugial area along and adjacent to the escarpment of the Moussalli et al (in press) central Wet Tropics.…”

Section: Introductionmentioning

confidence: 94%

Identification and dynamics of a cryptic suture zone in tropical rainforest

et al. 2009

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Suture zones, shared regions of secondary contact between long-isolated lineages, are natural laboratories for studying divergence and speciation. For tropical rainforest, the existence of suture zones and their significance for speciation has been controversial. Using comparative phylogeographic evidence, we locate a morphologically cryptic suture zone in the Australian Wet Tropics rainforest. Fourteen out of 18 contacts involve morphologically cryptic phylogeographic lineages, with mtDNA sequence divergences ranging from 2 to 15 per cent. Contact zones are significantly clustered in a suture zone located between two major Quaternary refugia. Within this area, there is a trend for secondary contacts to occur in regions with low environmental suitability relative to both adjacent refugia and, by inference, the parental lineages. The extent and form of reproductive isolation among interacting lineages varies across species, ranging from random admixture to speciation, in one case via reinforcement. Comparative phylogeographic studies, combined with environmental analysis at a fine-scale and across varying climates, can generate new insights into suture zone formation and to diversification processes in species-rich tropical rainforests. As arenas for evolutionary experimentation, suture zones merit special attention for conservation.

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“…In general, attempts to locate and circumscribe historical refugia in tropical rainforest systems have proved contentious (41,42), and the same is true for the Australian wet tropics where there is some discrepancy between inferences from paleoclimatic models (12), current phytogeography (17), and evidence for drier sclerophyll vegetation and burning within putative refugia (20). Although consistent phylogeographic divisions across the BMC in vertebrates support the division between the major northern and southern refugia predicted by modeling (22), further details are obscured for vertebrates by varying histories of local extinction and expansion, stochastic variance of gene trees, or both (43).…”

Section: Implications For Biogeography and Evolution In The Wet Tropicsmentioning

confidence: 99%

“…This long-term decline, and particularly the Pleistocene climate oscillations, appears to have driven cycles of contraction and expansion of rainforest, probably structured around montane remnants surrounded by dry sclerophyll woodlands (16). These montane blocks are centers of endemism and have been proposed as Pleistocene refugia (17)(18)(19), and form the basis of the recognized subregions within the Wet Tropics (see Table 1 and Fig. 1).…”

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confidence: 99%

Reconciling paleodistribution models and comparative phylogeography in the Wet Tropics rainforest land snailGnarosophia bellendenkerensis(Brazier 1875)

Hugall

Moritz

Moussalli

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

390

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Comparative phylogeography has proved useful for investigating biological responses to past climate change and is strongest when combined with extrinsic hypotheses derived from the fossil record or geology. However, the rarity of species with sufficient, spatially explicit fossil evidence restricts the application of this method. Here, we develop an alternative approach in which spatial models of predicted species distributions under serial paleoclimates are compared with a molecular phylogeography, in this case for a snail endemic to the rainforests of North Queensland, Australia. We also compare the phylogeography of the snail to those from several endemic vertebrates and use consilience across all of these approaches to enhance biogeographical inference for this rainforest fauna. The snail mtDNA phylogeography is consistent with predictions from paleoclimate modeling in relation to the location and size of climatic refugia through the late Pleistocene-Holocene and broad patterns of extinction and recolonization. There is general agreement between quantitative estimates of population expansion from sequence data (using likelihood and coalescent methods) vs. distributional modeling. The snail phylogeography represents a composite of both common and idiosyncratic patterns seen among vertebrates, reflecting the geographically finer scale of persistence and subdivision in the snail. In general, this multifaceted approach, combining spatially explicit paleoclimatological models and comparative phylogeography, provides a powerful approach to locating historical refugia and understanding species' responses to them. P hylogeography seeks to reveal biogeographical history of species and the habitats they occupy via (i) qualitative spatial association of divisions between monophyletic clusters of alleles with biogeographic barriers, and (ii) quantitative estimates of historical population size (1-4). Much of this work has focused on mitochondrial DNA; however, stochastic variance limits our confidence in reconstructions of history from a single gene. One approach solving this limitation is to sample more genes (5). A more common approach is comparative phylogeography (6) in which sequence variation is surveyed at a single gene for multiple species across the same landscape. A limitation here is that histories of local extinction and recolonization may vary among species despite a common history of habitat fluctuation.To improve inference of historical biogeography, we need to incorporate spatially explicit evidence from paleoecology into interpretation of species' phylogeography. Some recent studies have promoted the use of fossil evidence along with phylogeography to estimate historical distributions (7) or have examined sequence variation in the fossils themselves (e.g., refs. 8 and 9) However, appropriate fossils are sparse or nonexistent for most taxa. We explore a novel and more widely applicable approach that uses paleoclimatological models of species' distributions in conjunction with phylogeography.

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Australian rainforests: patterns and change

Cited by 186 publications

References 48 publications

Reproductive traits of tropical rain-forest trees in New Caledonia

Reproductive traits of tropical rain-forest trees in New Caledonia

Identification and dynamics of a cryptic suture zone in tropical rainforest

Reconciling paleodistribution models and comparative phylogeography in the Wet Tropics rainforest land snailGnarosophia bellendenkerensis(Brazier 1875)

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