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Understanding the extent of morphological variation in the wild population of Aldabra giant tortoises is important for conservation, as morphological variation in captive populations has been interpreted as evidence for lingering genes from extinct tortoise lineages. If true, this could impact reintroduction programmes in the region. The population of giant tortoises on Aldabra Atoll is subdivided and distributed around several islands. Although pronounced morphological variation was recorded in the late 1960s, it was thought to be a temporary phenomenon. Early researchers also raised concerns over the future of the population, which was perceived to have exceeded its carrying capacity. We analyzed monthly monitoring data from 12 transects spanning a recent 15-year period (1998–2012) during which animals from four subpopulations were counted, measured, and sexed. In addition, we analyzed survival data from individuals first tagged during the early 1970s. The population is stable with no sign of significant decline. Subpopulations differ in density, but these differences are mostly due to differences in the prevailing vegetation type. However, subpopulations differ greatly in both the size of animals and the degree of sexual dimorphism. Comparisons with historical data reveal that phenotypic differences among the subpopulations of tortoises on Aldabra have been apparent for the last 50 years with no sign of diminishing. We conclude that the giant tortoise population on Aldabra is subject to varying ecological selection pressures, giving rise to stable morphotypes in discrete subpopulations. We suggest therefore that (1) the presence of morphological differences among captive Aldabra tortoises does not alone provide convincing evidence of genes from other extinct species; and (2) Aldabra serves as an important example of how conservation and management in situ can add to the scientific value of populations and perhaps enable them to better adapt to future ecological p

Until recently, it was thought that dugongs (Dugong dugon) were extinct in the Seychelles. However, a collection of sightings at Aldabra Atoll, a World Heritage Site in the Seychelles, has renewed interest in dugong distribution in the western Indian Ocean. This article consolidates the records of dugong sightings held in the Aldabra Research Station library and explores their spatial patterning. The locations of sightings (2001-2009) are plotted onto a high-resolution benthic habitat map of the Aldabra lagoon created by classifying a QuickBird satellite remote-sensing image in January 2009. A spatial cluster detection procedure is applied to point records of sightings to reveal a statistically significant cluster of sightings in the north-west of the lagoon, at Bras Monsieur Clairemont, suggesting a mutual co-existence of dugongs and seagrass beds. A habitat suitability model combines the point data set of dugong sightings within the continuous benthic habitat map and identifies the central western area as containing the most suitable habitat for dugong inside the Aldabra lagoon.

Full Text, Thesis (PhD Doctorate), Doctor of Philosophy (PhD), School of Environmental and Applied Science, This thesis investigates historical and current dispersal in Mixophyes fleayi, an endangered, wet forest-restricted frog species, found exclusively on the Great Dividing Range of mid-eastern Australia. The phylogeographic structuring and genetic divergence among isolated forest fragments and the presence of multiple populations within continuous forest is used to investigate historical connectivity of populations and current dispersal. Indirect genetic methods as well as field based direct methods are also used to investigate dispersal and movement. These results are used to explore the consequences of dispersal in terms of conservation and management of the species. Few studies have investigated genetic differentiation between upland mesic rainforest areas in southern parts of Queensland, which potentially acted as historical refugia for rainforest dependant species. The broad scale investigation of genetic diversity and structure in M. fleayi, using sequence variation within the mitochondrial ND2 gene, revealed two scales of genetic structure. Two deeply divergent and geographically isolated lineages were found to group populations across the Brisbane River Valley, with isolation of the Conondale Range in the north from all other populations to the south. This can be attributed to regional isolation of rainforest fragments during the Pliocene. Lower levels of genetic variation and sequence divergence were found across forest fragments within the southern distribution of the species (Springbrook, Mount Barney, McPherson, Main, Upper Richmond and Nightcap Ranges), resulting from more recent fragmentation and restricted dispersal related to expansion and contraction of rainforest habitat during the Pleistocene. Genetic structure among populations indicates that comparatively high levels of genetic differentiation exist on very small geographic scales relative to other amphibian species. These data suggest isolation by distance within forest fragments and significant