Biogeographical concordance and efficiency of taxon indicators for establishing conservation priority in a tropical rainforest biota

Prioritizing areas for conservation requires the use of surrogates for assessing overall patterns of biodiversity. Effective surrogates will reflect general biogeographical patterns and the evolutionary processes that have given rise to these and their efficiency is likely to lie influenced by several factors, including the spatial scale of species turnover and the overall congruence of the biogeographical history. We examine patterns of surrogacy for insects, snails, one family of plants and vertebrates from rainforests of northeast Queensland, an area characterized by high endemicity and an underlying history of climate-induced vicariance. Nearly all taxa provided some level of prediction of the conservation values For others. However, despite an overall correlation of the patterns of species richness and complementarity, the efficiency of surrogacy was highly asymmetric.. snails and insects were strong predictors of conservation priorities for vertebrates, but not vice versa. These results confirm predictions that taxon surrogates can be effective in highly diverse tropical systems where there is a strong history of vicariant biogeography, but also indicate that correlated patterns for species richness and/or complementarity do not guarantee that one taxon will be efficient as a surrogate for another. In our case, the highly diverse and narrowly distributed invertebrates were more efficient as predictors than the less diverse and more broadly distributed vertebrates.

Latitudinal variability in symbiont specificity within the widespread scleractinian coral Plesiastrea versipora

We examined the genetic diversity of symbiotic dinoflagellates (Symbiodinium sp.) in the widespread hermatypic coral Plesiastrea versipora from tropical/subtropical (north-eastern Australia) and temperate waters (south-eastern Australia) using restriction fragment length polymorphisms of partial 18S ribosomal DNA (rDNA), together with sequence analysis of partial 28S rDNA. This study revealed that P. versipora associates with at least two distinct genotypes of symbiotic dinoflagellates and that the presence of these genotypes varies with latitude. P. versipora colonies from subtropical and tropical waters contained symbionts belonging to Symbiodinium clade C, while P. versipora colonies at high-latitude sites contained clade B. Variability within the two groups of symbionts (clades H and C) was minimal, suggesting possible host fidelity. The geographically distinct varieties of symbionts within the tissue of this hermatypic coral are likely to be associated with algal physiological differences, which in turn may relate to changing selective pressures as a function of latitude along the eastern Australian seaboard.

Can long-distance dispersal be inferred from the New Zealand plant fossil record?

New Zealand is generally thought to have been physically isolated from the rest of the world for over 60 million years. But physical isolation may not mean biotic isolation, at least on the time scale of millions of years. Are New Zealand's present complement of plants the direct descendants of what originally rafted from Gondwana? Or has there been total extinction of this initial flora with replacement through long-distance dispersal (a complete biotic turnover)? These are two possible extremes which have come under recent discussion. Can the fossil record be used to decide the relative importance of the two endpoints, or is it simply too incomplete and too dependent on factors of chance? This paper suggests two approaches to the problem-the use of statistics to apply levels of confidence to first appearances in the fossil record and the analysis of trends based on the entire palynorecord. Statistics can suggest that the first appearance of a taxon was after New Zealand broke away from Gondwana-as long as the first appearance in the record was not due to an increase in biomass from an initially rare state. Two observations can be drawn from the overall palynorecord that are independent of changes in biomass: (1) The first appearance of palynotaxa common to both Australia and New Zealand is decidedly non-random. Most taxa occur first in Australia. This suggests a bias in air or water transport from west to east. (2) The percentage of endemic palynospecies in New Zealand shows no simple correlation with the time New Zealand drifted into isolation. The conifer macrorecord also hints at complete turnover since the Cretaceous.

Patterns and levels of endemism in the Australian Wet Tropics rainforest: evidence from flightless insects

This study examines the level and pattern of endemism among 274 flightless rainforest insects found in the Wet Tropics region of Australia. Endemism is measured at two nested scales: (1) those confined to the Wet Tropics, termed 'regional endemics'; and (2) the subset of those species confined to a single subregion of the Wet Tropics, termed 'subregional endemics'. Fifty per cent of the regional endemic flightless insects are also subregional endemics compared with 15% of the known regional endemic vertebrates. The four subregions with the most endemic flightless insect species are the uplands of Mt Finnigan, Carbine, Bellenden-Ker/Bartle Frere and Atherton. Multiple regression suggests that the combination of rainforest area and shape explain the most variance (R-2 = 0.603) in the numbers of species of regional endemic insects. However, subregional endemism is not closely correlated with the size or shape of the subregions in which they occur, or a combination of these factors. Candidate refugial and recolonised subregions are identified, and are consistent with data from palaeoclimatic models and refugia identified using other taxa. We group upland subregions into larger areas of endemism using parsimony analysis of endemism. These groupings are consistent with our understanding of the history of the Wet Tropics rainforests.

Genetic consequences of sequential founder events by an island-colonizing bird

The importance of founder events in promoting evolutionary changes on islands has been a subject of long-running controversy. Resolution of this debate has been hindered by a lack of empirical evidence from naturally founded island populations. Here we undertake a genetic analysis of a series of historically documented, natural colonization events by the silvereye species-complex (Zosterops lateralis), a group used to illustrate the process of island colonization in the original founder effect model. Our results indicate that single founder events do not affect levels of heterozygosity or allelic diversity, nor do they result in immediate genetic differentiation between populations. Instead, four to five successive founder events are required before indices of diversity and divergence approach that seen in evolutionarily old forms. A Bayesian analysis based on computer simulation allows inferences to be made on the number of effective founders and indicates that founder effects are weak because island populations are established from relatively large flocks. Indeed, statistical support for a founder event model was not significantly higher than for a gradual-drift model for all recently colonized islands. Taken together, these results suggest that single colonization events in this species complex are rarely accompanied by severe founder effects, and multiple founder events and/or long-term genetic drift have been of greater consequence for neutral genetic diversity.

Spatial and temporal patterns in Australian wheat yield and their relationship with ENSO

Spatial and temporal variability in wheat production in Australia is dominated by rainfall occurrence. The length of historical production records is inadequate, however, to analyse spatial and temporal patterns conclusively. In this study we used modelling and simulation to identify key spatial patterns in Australian wheat yield, identify groups of years in the historical record in which spatial patterns were similar, and examine association of those wheat yield year groups with indicators of the El Nino Southern Oscillation (ENSO). A simple stress index model was trained on 19 years of Australian Bureau of Statistics shire yield data (1975-93). The model was then used to simulate shire yield from 1901 to 1999 for all wheat-producing shires. Principal components analysis was used to determine the dominating spatial relationships in wheat yield among shires. Six major components of spatial variability were found. Five of these represented near spatially independent zones across the Australian wheatbelt that demonstrated coherent temporal (annual) variability in wheat yield. A second orthogonal component was required to explain the temporal variation in New South Wales. The principal component scores were used to identify high- and low-yielding years in each zone. Year type groupings identified in this way were tested for association with indicators of ENSO. Significant associations were found for all zones in the Australian wheatbelt. Associations were as strong or stronger when ENSO indicators preceding the wheat season (April-May phases of the Southern Oscillation Index) were used rather than indicators based on classification during the wheat season. Although this association suggests an obvious role for seasonal climate forecasting in national wheat crop forecasting, the discriminatory power of the ENSO indicators, although significant, was not strong. By examining the historical years forming the wheat yield analog sets within each zone, it may be possible to identify novel climate system or ocean-atmosphere features that may be causal and, hence, most useful in improving seasonal forecasting schemes.

Monarchs across the Pacific: the Columbus hypothesis revisited

The 'Columbus hypothesis' suggests that the annual north-south return migration of Danaus plexippus in North America is a very recently evolved behaviour, less than 200 years old. This hypothesis rests, in part, on an analysis of the 19th century spread of the monarch across the Pacific that assumes a continuous east to west movement and is based predominantly on one publication. We review all the contemporary literature and present new analysis of the data. The movement of the monarch across the Pacific in the second half of the 19th century is best explained by a model which involves no more than three spot introductions, directly or indirectly aided by human movement, followed by natural spread of the monarch across island groups. Contemporary records refer to 'boom' and 'bust' population cycles on newly settled islands, which may have led to high rates of monarch movement. We see no evidence in the records to suggest an east to west sweep by monarch populations as suggested by the Columbus hypothesis. (C) 2004 The Linnean Society of London.

Monarchs in Australia: On the winds of a storm?

The monarch butterfly, Danaus plexippus, is one of Australia's best-known exotic butterflies, being first recorded here in the spring/summer of 1870/1871. However, the source of the original population is unknown. Using historical records we suggest that the most likely source of the founder population was from Vanuatu and/or New Caledonia. Many almost simultaneous 'first records' for the butterfly in Australia suggest that a large, well-distributed population was present when first noticed. While such a population may have developed from a limited number of individuals flying across the Coral Sea, the well documented, very dramatic appearance of large monarch populations in Australia does not appear to fit this model. Rather, we hypothesise that large numbers of monarchs were carried to Australia on cyclonic winds: no fewer that 3 cyclones hit the Queensland coast in early 1870. If one or more of these cyclones tracked from the Vanuatu/New Caledonia chain, then they may have transported monarchs. Once established on the central/northern Queensland coast, natural migration would account for the appearance of butterflies further south.

Distribution of the monarch butterfly, Danaus plexippus (L.) (Lepidoptera : Nymphalidae), in western North America

The standard model for the migration of the monarch butterfly in western North America has hitherto been movement in the autumn to overwintering sites in coastal California, followed by a return inland by most individuals in the spring. This model is based largely on observational and limited tagging and recovery data. In this paper we test the model by plotting many years of museum and collection records on a monthly basis on a map of the region. Our plots suggest a movement of Oregon, Washington and other north-western populations of summer butterflies to California in the autumn, but movement of more north-easterly populations (e.g. from Idaho and Montana) along two pathways through Nevada, Utah and Arizona to Mexico. The more westerly of these two pathways may follow the Colorado River south as indicated by museum records and seasonal temperature data. The eastern pathway may enter northern Utah along the western scarp of the Wasatch Mountains and run south through Utah and Arizona. Further analysis of distributions suggests that monarch butterflies in the American West occur primarily along rivers, and there are observations indicating that autumn migrants often follow riparian corridors. More data are needed to test our new model; we suggest the nature of the data required. (c) 2005 The Linnean Society of London.

Feral goat eradications on islands

Introduced mammals are major drivers of extinction. Feral goats (Capra hircus) are particularly devastating to island ecosystems, causing direct and indirect impacts through overgrazing, which often results in ecosystem degradation and biodiversity loss. Removing goat populations from islands is a powerful conservation tool to prevent extinctions and restore ecosystems. Goats have been eradicated successfully from 120 islands worldwide. With newly developed technology and techniques, island size is perhaps no longer a limiting factor in the successful removal of introduced goat populations. Furthermore,. the use of global positioning systems, geographic information systems, aerial hunting by helicopter specialized bunting dogs, and Judas goats has dramatically increased efficiency and significantly reduced the duration of eradication campaigns. Intensive monitoring programs are also critical for successful eradications. Because of the presence of humans with domestic goat populations on large islands, future island conservation actions will require eradication programs that involve local island inhabitants in a collaborative approach with biologists, sociologists, and educators. Given the clear biodiversity benefits, introduced goat populations should be routinely removed from islands.

Conservation action in the Galapagos: Feral pig (Sus scrofa) eradication from Santiago Island

Introduced mammals are major drivers of extinction and ecosystem change. As omnivores, feral pigs (Sus scrofa) are responsible for wholesale adverse effects on islands. Here, we report on the eradication of feral pigs from Santiago Island in the Galápagos Archipelago, Ecuador, which is the largest insular pig removal to date. Using a combination of ground hunting and poisoning, over 18,000 pigs were removed during this 30-year eradication campaign. A sustained effort, an effective poisoning campaign concurrent with the hunting program, access to animals by cutting more trails, and an intensive monitoring program all proved critical to the successful eradication. While low and fluctuating control efforts may help protect select native species, current eradication methods, limited conservation funds, and the potential negative non-target impacts of sustained control efforts all favor an intense eradication effort, rather than a sustained control program. The successful removal of pigs from Santiago Island sets a new precedent, nearly doubling the current size of a successful eradication, and is leading to more ambitious projects. However, now we must turn toward increasing eradication efficiency. Given limited conservation funds, we can no longer afford to spend decades removing introduced mammals from islands.