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The discipline of historical biogeography seeks to understand the contribution of earth history to the generation of biodiversity. Traditionally, the study of historical biogeography has been approached by examining the distribution of a biota at or above the species level. While this approach has provided important insights into the relationship between biological diversity and earth history, a significant amount of information recorded below the species level (intraspecific variation), regarding the biogeographical history of a region, may be lost. The application of phylogeography - which considers information recorded below the species level - goes some way to addressing this problem. Patterns of intraspecific molecular variation in wide-ranging taxa can be useful for inferring biogeography, and can also be used to test competing biogeographical hypotheses (often based on the dispersal-vicariance debate). Moreover, it is argued here that phylogeographical studies have recently begun to unite these two disparate views, in the recognition that both dispersal and vicariance have played fundamental roles in the generation of biodiversity. Freshwater dependent taxa are ideal model organisms for the current field of research, as they reflect well the underlying biogeographical history of a given region, due to limited dispersal abilities - their requirement for freshwater restricts them. To this end, this study documented the phylogeographical history of the giant freshwater prawn (Macrobrachium rosenbergii) utilising both mitochondrial (COI & 16S) and nuclear (microsatellite) markers. Samples (n = ~1000) were obtained from across most of the natural distribution of M. rosenbergii [Southern and South East (SE) Asia, New Guinea, northern Australia]. Initial phylogenetic analyses identified two highly divergent forms of this species restricted to either side of Huxley's extension of Wallace's Line; a pattern consistent with ancient vicariance across the Makassar Strait. Subsequent analyses of molecular variation within the two major clades specifically tested a number of biogeographical hypotheses, including that: 1.) a major biogeographical transition zone between the Sundaic and Indochinese biotas, located just north of the Isthmus of Kra in SE Asia, results from Neogene marine transgressions that breached the Isthmus in two locations for prolonged periods of time; 2.) Australia's Lake Carpentaria [circa 80 000 - 8 500 before present (BP)] facilitated genetic interchange among freshwater organisms during the Late Pleistocene; 3.) sea-level fluctuations during the Pleistocene constrained evolutionary diversification of M. rosenbergii within the Indo-Australian Archipelago (IAA); and 4.) New Guinea's Fly River changed course from its current easterly outflow to flow westwards into Lake Carpentaria during the Late Pleistocene. The results support hypotheses 1-3, but not 4. The potential for phylogeography to contribute significantly to the study of historical biogeography is also discussed.

In recent years landscape-scale fires have occurred in mainland Southeast Asia, including important protected areas (PAs). There has been increasing concern that landscape-scale fires are degrading the seasonally dry evergreen forest (SEF) element of the forest mosaic to more open deciduous forest and savanna, with serious implications for biodiversity conservation. Present management approaches, including fire suppression and prescribed burning, have not been effective managing for landscape-scale fire. Research was undertaken to investigate the occurrence, cause, effect, frequency and predictability of fire in SEF. SEF has the greatest species biodiversity in the forest mosaic and is potentially the most affected by fire, yet little research has been done on fire in SEF in mainland Southeast Asia. Huai Kha Khaeng (HKK) Wildlife Sanctuary in Thailand was selected as the study area. The objectives included: 1) investigate the area of SEF burned in HKK from 1988 to 2002; 2) investigate the conditions for fire in SEF; 3) determine whether the area of SEF in HKK declined as a result of fire; 4) determine the frequency of fire season years between 1984 and 2001 with the conditions for fire spread in SEF; and 5) determine whether there is a significant relationship between pre-fire season drought codes (Keetch-Byram Drought Index (KBDI) and Canadian Drought Code (DC)) and identified SEF fire season years for 1981 to 2003. Methods included: development of a Landsat fire history with associated interviews and reconnaissance field checks; fieldwork lighting test fires and measuring fuel characteristics; remote sensing change detection work using Landsat imagery; generation of a twenty-one year daily relative humidity minimum record for SEF; and logistic regression of the pre-fire season drought code values with identified SEF ‘fire’ and ‘non-fire’ years. Results showed: 1. Extensive areas of SEF have burned, but that Landsat imagery was not suitable for detecting fire in intact SEF. 2. SEF burned in years when there were fires burning adjacent to SEF in mid March and the moisture content of the SEF leaf litter fuel was less than 15%. 3. Fifteen percent of SEF in HKK has been either degraded or converted to deciduous forest forms in 12 years. 4. Conditions for fire spread in SEF occurred four times in 17 consecutive years. 5. A significant relationship exists between both the Keetch-Byram Drought Code (KBDI) and Canadian Drought Code (DC) and the SEF fire years. Implications are that large-scale fires have adversely affected intact SEF in HKK, and that the current damaging situation can be expected to continue. Whereas the extent of burning in intact SEF is not known, the need to manage the situation is immediate. Landscape-scale fires in HKK can be managed by using January 31st drought code values to predict potential large-scale fire years, followed by an aggressive fire suppression campaign in those years. In other years, fires can be allowed to burn without serious threat to the forest mosaic, and should to some extent be encouraged to maintain open deciduous forests and savanna. Additional research is required to determine whether a similar approach can be used for protected areas in other parts of the region.