Speciation and phylogeography in Caridina indistincta, a complex of freshwater shrimps from Australian heathland streams

The Caridina indistincta complex is a group of closely related atyid shrimps that inhabit coastal freshwater streams throughout north-eastern Australia. Using mitochondrial DNA sequence data (cytochrome oxidase 1, CO1), we (1) inferred the timing of speciation in the C. indistincta group and (2) examined the intraspecific phylogeographic patterns within the group. Assuming a shrimp-specific rate of CO1 evolution, the level of sequence divergence among species suggests that speciation took place during the Miocene epoch. Within one widespread mainland species, phylogeographic patterns suggest strong geographic 'regionalisation' of mtDNA lineages that are most likely of Pleistocene origin. By contrast, another species comprises two highly divergent mtDNA lineages that occur in sympatry. We suggest that although Pleistocene sea-level regressions appear important in generating population-level phylogeographic patterns, these events were largely unimportant in the formation of species in this group.

Molecular phylogeny and biogeography of the dung beetle genus Temnoplectron Westwood (Scarabaeidae: Scarabaeinae) from Australia’s wet tropics

The landscape of the Australian Wet Tropics can be described as islands of montane rainforest Surrounded by warmer or more xeric habitats. Historical glaciation cycles have caused expansion and contraction of these rainforest islands leading to consistent patterns of genetic divergence within species of vertebrates. To explore whether this dynamic history has promoted speciation in endemic and diverse groups Of insects, we used a combination of mtDNA sequencing and morphological characters to estimate relationships and the tempo of divergence among Australian representatives of the dung beetle genus Temnoplectron. This phylogenetic hypothesis shares a number of well-supported clades with a previously published phylogenetic hypothesis based on morphological data. though statistical support for several nodes is weak. Sister species relationships well-supported in both tree topologies. and a tree obtained by combining the two data sets. suggest that speciation has mostly been allopatric. We identify a number of speciation barriers, which coincide with phylogeographic breaks found in vertebrate species. Large sequence divergences between species emphasize that speciation events are ancient (pre-Pleistocene). The flightless, rainforest species appear to have speciated rapidly. but also in the distant past. (C) 2003 Elsevier Inc. All rights reserved.

The public's knowledge of and support for conservation of Australia's tree-kangaroos and other animals

After providing background on Dendrolagus species in Australia, two consecutive surveys of Brisbane's residents are used to assess public knowledge of tree-kangaroos and the stated degree of support for their conservation in Australia. The responses of participants in Survey I are based on their pre-survey knowledge of wildlife. The same set of participants completed Survey II after being provided with additional information on all the wildlife species mentioned in Survey I. Changes in the attitudes of respondents and their degree of support for the protection and conservation of Australia's tree-kangaroos are measured, including changes in their contingent valuations and stated willingness to provide financial support for such conservation. Reasons for wanting to protect tree-kangaroos are specified and analysed. Furthermore, changes that occur in the relative importance of these reasons with increased knowledge are also examined. Support for the conservation of tree-kangaroos is found to rise with the additional knowledge supplied about all species and is compared with variations in support for protection of other mammals. Support for the conservation of Australia's less well known tropical mammals is found to increase relative to better known mammals (icons) present in temperate areas, such as koalas and red kangaroos. Possible implications of the results for government conservation policies in Australia are examined.

Phenotypic divergence along lines of genetic variance

Natural populations inhabiting the same environment often independently evolve the same phenotype. Is this replicated evolution a result of genetic constraints imposed by patterns of genetic covariation? We looked for associations between directions of morphological divergence and the orientation of the genetic variance-covariance matrix (G) by using an experimental system of morphological evolution in two allopatric nonsister species of rainbow fish. Replicate populations of both Melanotaenia eachamensis and Melanotaenia duboulayi have independently adapted to lake versus stream hydrodynamic environments. The major axis of divergence (z) among all eight study populations was closely associated with the direction of greatest genetic variance (g(max)), suggesting directional genetic constraint on evolution. However, the direction of hydrodynamic adaptation was strongly associated with vectors of G describing relatively small proportions of the total genetic variance, and was only weakly associated with g(max). In contrast, divergence between replicate populations within each habitat was approximately proportional to the level of genetic variance, a result consistent with theoretical predictions for neutral phenotypic divergence. Divergence between the two species was also primarily along major eigenvectors of G. Our results therefore suggest that hydrodynamic adaptation in rainbow fish was not directionally constrained by the dominant eigenvector of G. Without partitioning divergence as a consequence of the adaptation of interest (here, hydrodynamic adaptation) from divergence due to other processes, empirical studies are likely to overestimate the potential for the major eigenvectors of G to directionally constrain adaptive evolution.

Growth performance and management of a mixed rainforest tree plantation

Monoculture plantations of Pinus, Eucalyptus and Acacia have been established oil rainforest lands throughout the world. However, this type of reforestation generally supplies low quality timber and contributes to landscape simplification. Alternatives to exotic monoculture plantations are now beginning to gain momentum with farmers and landholders attempting to establish a variety of rainforest trees in small plantations. When compared to the well studied commercial species, knowledge concerning the growth and management of many of these rainforest species is in its infancy. To help expand this limited knowledge base an experimental plantation of 16 rainforest tree species in a randomised design was established near Mt. Mee, in south-eastern Queensland, Australia. Changes in growth, form (based on stem straightness, branch size and branchiness), crown diameters and leaf area of each species were examined over 5 years. Patterns of height growth were also measured monthly for 31 months. Species in this trial could be separated into three groups based on their overall growth after 5 years and their growth patterns. Early successional status, low timber density, high maximum photosynthetic rates and large total leaf areas were generally correlated to rapid height growth. Several species (including Araucaria cunninghamii, Elaeocarpus grandis, Flindersia brayleyana, Grevillea robusta and Khaya nyasica) had above average form and growth, while all species in the trial had considerable potential to have increased productivity through tree selection. As canopy closure occurred at the site between years four and five, growth increments declined. To reduce stand competition a number of different thinning techniques could be employed. However, simple geometric or productivity based thinnings appear to be inappropriate management techniques for this mixed species stand as they would either remove many of the best performing trees or nearly half the species in the trial. Alternatively, a form based thinning would maintain the site's diversity, increase the average form of the plantation and provide some productivity benefits.

To self, or not to self ... A review of outcrossing and pollen-mediated gene flow in neotropical trees

Despite the typically low population densities and animal-mediated pollination of tropical forest trees, outcrossing and long-distance pollen dispersal are the norm. We reviewed the genetic literature on mating systems and pollen dispersal for neotropical trees to identify the ecological and phylogenetic correlates. The 36 studies surveyed found >90% outcrossed mating for 45 hermaphroditic or monoecious species. Self-fertilization rates varied inversely with population density and showed phylogenetic and geographic trends. The few direct measures of pollen flow (N = 11 studies) suggest that pollen dispersal is widespread among low-density tropical trees, ranging from a mean of 200 m to over 19 km for species pollinated by small insects or bats. Future research needs to examine (1) the effect of inbreeding depression on observed outcrossing rates, (2) pollen dispersal in a wide range of pollination syndromes and ecological classes, (3) and the range of variation of mating system expression at different hierarchical levels, including individual, seasonal, population, ecological, landscape and range wide.

Regional and population-scale influences on genetic diversity partitioning within costa rican populations of the pioneer tree Vochysia ferruginea mart.

The neotropical pioneer species Vochysia ferruginea is locally important for timber and is being increasingly exploited. The sustainable utilisation of this species would benefit from an understanding of the level and partitioning of genetic diversity within remnant and secondary regrowth populations. We used data from total genome (amplified fragment length polymorphism, AFLP) and chloroplast genome markers to assay diversity levels within seven Costa Rican populations. Significant chloroplast differentiation between Atlantic and Pacific watersheds was observed, suggesting divergent historical origins for these populations. Contemporary gene flow, though extensive, is geographically constrained and a clear pattern of isolation by distance was detectable when an inter-population distance representing gene flow around the central Costa Rican mountain range was used. Overall population differentiation was low (F-ST = 0.15) and within-population diversity high, though variable (H-s=0.16-0.32), which fits with the overall pattern of population genetic structure expected for a widespread, outcrossed tropical tree. However genetic diversity was significantly lower and differentiation higher for recently colonised and disturbed populations compared to that at more established sites. Such a pattern seems indicative of a pioneer species undergoing repeated cycles of colonisation and succession.

Applying network analysis to the conservation of habitat trees in urban environments: a case study from Brisbane, Australia

In Australia more than 300 vertebrates, including 43 insectivorous bat species, depend on hollows in habitat trees for shelter, with many species using a network of multiple trees as roosts, We used roost-switching data on white-striped freetail bats (Tadarida australis; Microchiroptera: Molossidae) to construct a network representation of day roosts in suburban Brisbane, Australia. Bats were caught from a communal roost tree with a roosting group of several hundred individuals and released with transmitters. Each roost used by the bats represented a node in the network, and the movements of bats between roosts formed the links between nodes. Despite differences in gender and reproductive stages, the bats exhibited the same behavior throughout three radiotelemetry periods and over 500 bat days of radio tracking: each roosted in separate roosts, switched roosts very infrequently, and associated with other bats only at the communal roost This network resembled a scale-free network in which the distribution of the number of links from each roost followed a power law. Despite being spread over a large geographic area (> 200 km(2)), each roost was connected to others by less than three links. One roost (the hub or communal roost) defined the architecture of the network because it had the most links. That the network showed scale-free properties has profound implications for the management of the habitat trees of this roosting group. Scale-free networks provide high tolerance against stochastic events such as random roost removals but are susceptible to the selective removal of hub nodes. Network analysis is a useful tool for understanding the structural organization of habitat tree usage and allows the informed judgment of the relative importance of individual trees and hence the derivation of appropriate management decisions, Conservation planners and managers should emphasize the differential importance of habitat trees and think of them as being analogous to vital service centers in human societies.

Genetic population structure and call variation in a passerine bird, the satin bowerbird, Ptilonorhynchus violaceus

Geographic variation in vocalizations is widespread in passerine birds, but its origins and maintenance remain unclear. One hypothesis to explain this variation is that it is associated with geographic isolation among populations and therefore should follow a vicariant pattern similar to that typically found in neutral genetic markers. Alternatively, if environmental selection strongly influences vocalizations, then genetic divergence and vocal divergence may be disassociated. This study compared genetic divergence derived from 11 microsatellite markers with a metric of phenotypic divergence derived from male bower advertisement calls. Data were obtained from 16 populations throughout the entire distribution of the satin bowerbird, an Australian wet-forest-restricted passerine. There was no relationship between call divergence and genetic divergence, similar to most other studies on birds with learned vocalizations. Genetic divergence followed a vicariant model of evolution, with the differentiation of isolated populations and isolation-by-distance among continuous populations. Previous work on Ptilonorhynchus violaceus has shown that advertisement call structure is strongly influenced by the acoustic environment of different habitats. Divergence in vocalizations among genetically related populations in different habitats indicates that satin bowerbirds match their vocalizations to the environment in which they live, despite the homogenizing influence of gene flow. In combination with convergence of vocalizations among genetically divergent populations occurring in the same habitat, this shows the overriding importance that habitat-related selection can have on the establishment and maintenance of variation in vocalizations.

Biodiversity conservation planning tools: Present status and challenges for the future

Species extinctions and the deterioration of other biodiversity features worldwide have led to the adoption of systematic conservation planning in many regions of the world. As a consequence, various software tools for conservation planning have been developed over the past twenty years. These, tools implement algorithms designed to identify conservation area networks for the representation and persistence of biodiversity features. Budgetary, ethical, and other sociopolitical constraints dictate that the prioritized sites represent biodiversity with minimum impact on human interests. Planning tools are typically also used to satisfy these criteria. This chapter reviews both the concepts and technical choices that underlie the development of these tools. Conservation planning problems can be formulated as optimization problems, and we evaluate the suitability of different algorithms for their solution. Finally, we also review some key issues associated with the use of these tools, such as computational efficiency, the effectiveness of taxa and abiotic parameters at choosing surrogates for biodiversity, the process of setting explicit targets of representation for biodiversity surrogates, and

Roost tree characteristics determine use by the white-striped freetail bat (Tadarida australis, Chiroptera : Molossidae) in suburban subtropical Brisbane, Australia

We examined factors affecting roost tree selection by the white-striped freetail bat Tadarida australis (Chiroptera: Molossidae), a large insectivorous bat in suburban Brisbane, Australia. We compared biophysical characteristics associated with 34 roost trees and 170 control trees of similar diameter, height and tree senescence characters. Roost trees used by the white-striped freetail bat had significantly higher numbers of hollows in the trunk and branches (P < 0.003) and were more likely to contain a large trunk cavity with an internal diameter of > 30 cm (P < 0.001) than control trees. These trees also accommodated more species of hollow-using fauna (P = 0.005). When comparing roost trees with control trees of similar diameters and heights, roost trees were on average at a later stage of tree senescence (P < 0.001). None of the roost trees were found in the large forest reserves fringing the Brisbane metropolitan area despite these areas being used for foraging by the white-striped freetail bat. Although all tree locations in this study were in modified landscapes, roost trees tended to be surrounded by groups of trees and undergrowth. Roost trees provide important habitat requirements for hollow-using fauna in suburban, rural and forested environments.

Modeling the age of tropical moist forest fragments in heavily-cleared lowland landscapes of Colombia

Increasingly, large areas of native tropical forests are being transformed into a mosaic of human dominated land uses with scattered mature remnants and secondary forests. In general, at the end of the land clearing process, the landscape will have two forest components: a stable component of surviving mature forests, and a dynamic component of secondary forests of different ages. As the proportion of mature forests continues to decline, secondary forests play an increasing role in the conservation and restoration of biodiversity. This paper aims to predict and explain spatial and temporal patterns in the age of remnant mature and secondary forests in lowland Colombian landscapes. We analyse the age distributions of forest fragments, using detailed temporal land cover data derived from aerial photographs. Ordinal logistic regression analysis was applied to model the spatial dynamics of mature and secondary forest patches. In particular, the effect of soil fertility, accessibility and auto-correlated neighbourhood terms on forest age and time of isolation of remnant patches was assessed. In heavily transformed landscapes, forests account for approximately 8% of the total landscape area, of which three quarters are comprised of secondary forests. Secondary forest growth adjacent to mature forest patches increases mean patch size and core area, and therefore plays an important ecological role in maintaining landscape structure. The regression models show that forest age is positively associated with the amount of neighbouring forest, and negatively associated with the amount of neighbouring secondary vegetation, so the older the forest is the less secondary vegetation there is adjacent to it. Accessibility and soil fertility also have a negative but variable influence on the age of forest remnants. The probability of future clearing if current conditions hold is higher for regenerated than mature forests. The challenge of biodiversity conservation and restoration in dynamic and spatially heterogeneous landscape mosaics composed of mature and secondary forests is discussed. (c) 2004 Elsevier B.V. All rights reserved.

Comparative phylogeography of two open forest frogs from eastern Australia

We investigated the phylogeography of two closely related Australian frog species from open forest habitats, Limnodynastes tasmaniensis and L. peronii, using mitochondrial ND4 sequence data. Comparison of our results with previous work on Litoria fallax allowed us to test the generality of phylogeographic patterns among non-rainforest anurans along the east coast of Australia. In general, there was no strong evidence for congruence between overall patterns of genetic structure in the three species. However, phylogenetic breaks congruent with the position of the Burdekin Gap were detected at some level in all species. As previously noted for closed forest taxa, this area of dry habitat appears to have been an important influence on the evolution of several open forest taxa. There were broad geographic similarities in the phylogenetic structuring of southern populations of L. peronii and L. tasmaniensis. Contrarily, although the McPherson Range has previously been noted to coincide geographically with a major mtDNA phylogenetic break in Litoria fallax this pattern is not apparent in L. peronii or L. tasmaniensis. It appears that major phylogeographic splits within L. peronii and L. tasmaniensis may predate the Quaternary. We conclude that phylogeographies of open forest frogs are complex and more difficult to predict than for rainforest taxa, mainly due to an absence of palaeomodels for historical distributions of non-rainforest habitats. (C) 2001 The Linnean Society of London.

Improving drought tolerance in rainfed lowland rice: An example from Thailand

A large portion of the world's poor farm in rainfed systems where the water supply is unpredictable and droughts are common. In Thailand there are approximately 6.2 million ha of rain fed lowland rice, which account for 67% of the country's total rice-growing area. This rice system is often characterised by too much and too little water in the same season. Farmers' estimates of their annual losses to drought are as high as 45% in the upper parts of the toposequence. In contrast to irrigated rice systems, gains from crop improvement of rainfed rice have been modest, in part because there has been little effort to breed and select for drought tolerance for the target rainfed environments. The crop improvement strategy being used in Thailand considers three mechanisms that influence yield in the drought prone targets: yield potential as an important mechanism for mild drought (where yield loss is less than 50%), drought escape (appropriate phenology) and drought tolerance traits of leaf water potential, sterility, flower delay and drought response index for more severe drought conditions. Genotypes are exposed to managed drought environments for selection of drought tolerant genotypes. A marker assisted selection (MAS) scheme has been developed and applied for selection of progenies in the backcrossing program. The plant breeding program uses rapid generation advance techniques that enable early yield testing in the target population of environments (TPE) through inter-station (multi-location yield testing) and on-farm trials. A farmer participatory approach has been used to identify the TPE for the breeding program. Four terrace paddy levels have been identified, upper (drought), middle (drought prone to favorable) and lower (flooded). This paper reports the change in the breeding program for the drought prone tainted lowland rice environments of North and Northeast Thailand by incorporating our knowledge on adaptation and on response of rice to drought. (c) 2005 Elsevier B.V. All rights reserved.

Modelling the conversion of Colombian lowland ecosystems since 1940: Drivers, patterns and rates

In biologically mega-diverse countries that are undergoing rapid human landscape transformation, it is important to understand and model the patterns of land cover change. This problem is particularly acute in Colombia, where lowland forests are being rapidly cleared for cropping and ranching. We apply a conceptual model with a nested set of a priori predictions to analyse the spatial and temporal patterns of land cover change for six 50-100 km(2) case study areas in lowland ecosystems of Colombia. Our analysis included soil fertility, a cost-distance function, and neighbourhood of forest and secondary vegetation cover as independent variables. Deforestation and forest regrowth are tested using logistic regression analysis and an information criterion approach to rank the models and predictor variables. The results show that: (a) overall the process of deforestation is better predicted by the full model containing all variables, while for regrowth the model containing only the auto-correlated neighbourhood terms is a better predictor; (b) overall consistent patterns emerge, although there are variations across regions and time; and (c) during the transformation process, both the order of importance and significance of the drivers change. Forest cover follows a consistent logistic decline pattern across regions, with introduced pastures being the major replacement land cover type. Forest stabilizes at 2-10% of the original cover, with an average patch size of 15.4 (+/- 9.2) ha. We discuss the implications of the observed patterns and rates of land cover change for conservation planning in countries with high rates of deforestation. (c) 2005 Elsevier Ltd. All rights reserved.