Lesley Hughes

Biological consequences of global warming: is the signal already apparent?

Increasing greenhouse gas concentrations are expected to have significant impacts on the worlds climate on a timescale of decades to centuries. Evidence from long-term monitoring studies is now accumulating and suggests that the climate of the past few decades is anomalous compared with past climate variation, and that recent climatic and atmospheric trends are already affecting species physiology, distribution and phenology.

Predicting Dispersal Spectra: A Minimal Set of Hypotheses Based on Plant Attributes

1 The dispersal mode adopted by a plant species is frequently associated with other attributes of the plant and its habitat. In this paper we review these associations and present a set of hypotheses which, when considered together, make a probabilistic prediction of the dispersal mode adopted by a plant species. When applied to a species list, the hypotheses can be used to generate a prediction of its dispersal spectrum, i.e. the percentages of different dispersal modes that have been adopted. 2 The formulation of such a set of hypotheses has several purposes: (i) to summarize existing knowledge about dispersal adaptations and their interrelations with other attributes of plants and their habitats; (ii) to couch that knowledge in such a way that falsifiable predictions can be made; (iii) to arrive at provisional conclusions about which factors are the most important in shaping the evolution of dispersal mode in different plants or different environments. 3 The review of relationships between dispersal mode and other attributes of plants and their habitats lead to the following provisional conclusions; (i) seeds larger than 100 mg tend to be adapted for dispersal by vertebrates while those smaller than 0.1 mg tend to be unassisted; most seeds, however, are between 0.1 and 100 mg, and in this range all of the dispersal modes are feasible; (ii) plant growth form and stature (sometimes in relation to the canopy height of the vegetation) seem to exclude certain dispersal modes; (iii) the availability of specific dispersal vectors seems rarely to be an important determinant of dispersal mode; (iv) attributes of the physical environment also seem rarely to be important, except indirectly through their influence on plant stature and seed size.

Major conservation policy issues for biodiversity in oceania

Oceania is a diverse region encompassing Australia, Melanesia, Micronesia, New Zealand, and Polynesia, and it contains six of the worlds 39 hotspots of diversity. It has a poor record for extinctions, particularly for birds on islands and mammals. Major causes include habitat loss and degradation, invasive species, and overexploitation. We identified six major threatening processes (habitat loss and degradation, invasive species, climate change, overexploitation, pollution, and disease) based on a comprehensive review of the literature and for each developed a set of conservation policies. Many policies reflect the urgent need to deal with the effects of burgeoning human populations (expected to increase significantly in the region) on biodiversity. There is considerable difference in resources for conservation, including people and available scientific information, which are heavily biased toward more developed countries in Oceania. Most scientific publications analyzed for four threats (habitat loss, invasive species, overexploitation, and pollution) are from developed countries: 88.6% of Web of Science publications were from Australia (53.7%), New Zealand (24.3%), and Hawaiian Islands (10.5%). Many island states have limited resources or expertise. Even countries that do (e.g., Australia, New Zealand) have ongoing and emerging significant challenges, particularly with the interactive effects of climate change. Oceania will require the implementation of effective policies for conservation if the regions poor record on extinctions is not to continue.

Phenological changes in the southern hemisphere.

Current evidence of phenological responses to recent climate change is substantially biased towards northern hemisphere temperate regions. Given regional differences in climate change, shifts in phenology will not be uniform across the globe, and conclusions drawn from temperate systems in the northern hemisphere might not be applicable to other regions on the planet. We conduct the largest meta-analysis to date of phenological drivers and trends among southern hemisphere species, assessing 1208 long-term datasets from 89 studies on 347 species. Data were mostly from Australasia (Australia and New Zealand), South America and the Antarctic/subantarctic, and focused primarily on plants and birds. This meta-analysis shows an advance in the timing of spring events (with a strong Australian data bias), although substantial differences in trends were apparent among taxonomic groups and regions. When only statistically significant trends were considered, 82% of terrestrial datasets and 42% of marine datasets demonstrated an advance in phenology. Temperature was most frequently identified as the primary driver of phenological changes; however, in many studies it was the only climate variable considered. When precipitation was examined, it often played a key role but, in contrast with temperature, the direction of phenological shifts in response to precipitation variation was difficult to predict a priori. We discuss how phenological information can inform the adaptive capacity of species, their resilience, and constraints on autonomous adaptation. We also highlight serious weaknesses in past and current data collection and analyses at large regional scales (with very few studies in the tropics or from Africa) and dramatic taxonomic biases. If accurate predictions regarding the general effects of climate change on the biology of organisms are to be made, data collection policies focussing on targeting data-deficient regions and taxa need to be financially and logistically supported.

Convergence of elaiosomes and insect prey: evidence from ant foraging behaviour and fatty acid composition

1. Elaiosomes are lipid-rich appendages on the seeds of some plant species that promote dispersal of the seeds by ants. In this study we investigated the hypothesis that elaiosomes on seeds have converged in composition and attractiveness with the insect prey of ants. 2. The fatty acid compositions of 12 species of elaiosomes were compared to seeds of the same species and to seven orders of insects. The fatty acid compositions of the elaiosomes were more like those of insects than seeds; the levels of palmitic, palmitoleic, stearic and oleic acids in elaiosomes and insects were particularly similar. 3. The response of six ant species to the diglyceride 1,2-diolein was compared. This lipid is purported to be the principal attractant in elaiosomes and a review of the literature revealed that it is also an important component of insect haemolymph

Climate change and its impact on Australia's avifauna

Abstract Relative to the northern hemisphere, little is known about the effect of climate change on southern hemisphere birds, although the impact could be significant. Here we review the effects of climate change on birds that have been documented or predicted, with particular reference to Australian species. Potential impacts include changes in geographic range, movement patterns, morphology, physiology, abundance, phenology and community composition. The evidence suggests that these changes are already happening, both overseas and in Australia, but more research is needed to determine the extent of these impacts and how to conserve birds in the face of climate change. Management options include promoting adaptation and resilience, intensive management of sensitive species, and improved planning for mitigation techniques and monitoring.

Removal Rates of Seeds Adapted for Dispersal by Ants

To learn what scope there may be for a mother plant to modify whether her seeds are removed by ants, and how quickly, we investigated (1) how initial seed removal by ants may vary in times (years, season, time of day) and space (within and between sites, and (2) how large these sources of variation are. We focused on seed of two common ant—dispersed species in a field experiment on 20 x 20 m plots at each o three sites in Kuringai Chase National Park in southeast Australia. The most important influence on removal rate over the first 12 h of exposure was the precise location of seeds on the ground (54% of total variation). This variation did not persist over longer periods of time and, except during winter, all seeds had a high probability of being removed within 2—3 d. Time of year also had a strong influence had a strong influence on removal rate (21% of total variation) with the highest rates occurring in summer and the lowest in winter. These changes were mainly attributable to changes in ambient temperature. Differences in removal rates between the two seed species used was the third most important source of variation (4%). There was significant variation in removal rate between the same months in different years, in two of the three between—year comparisons. The effect of year, and of interactions between year and other factors, accounted for between 7 and 18% of total variation. Complementary experiments showed that ants were the only important removers of seed at the study sites and that seed age up to 1 yr did not influence removal rate. Experiments comparing removal rates of clumped seeds to those of single seeds showed no consistence difference. The high probability of removal of elaiosome—bearing seeds within 2—3 d of seedfall means it is unlikely that ant—dispersed plants in this vegetation ever face the problem of their seeds not being encountered and transported by an ant. Instead, the problem may be how to be removed by those ant species whose behavior will give the seed the best chance of survival and establishment.

Effects of elevated CO2 on five plant‐aphid interactions

We investigated interactions between five species of phloem‐feeding aphids (Homoptera: Aphididae) and their host plants at elevated CO2; Acyrthosiphon pisum (Harris) on Vicia faba L., Aphis nerii Boyer de Fonscolombe on Asclepias syriaca L., Aphis oenotherae Oestlund on Oenothera biennis L., Aulacorthum solani (Kaltenbach) on Nicotiana sylvestris Speg. & Comes and Myzus persicae (Sulzer) on Solanum dulcamara L. Host plants grown at elevated CO2 generally had greater biomass, leaf area and C:N ratios than those grown at ambient CO2, while plants with aphids had lower biomass and leaf area than those without aphids.

Mobile Gene Cassettes: A Fundamental Resource For Bacterial Evolution

Horizontal gene transfer increases genetic diversity in prokaryotes to a degree not allowed by the limitations of reproduction by binary fission. The integron/gene cassette system is one of the most recently characterized examples of a system that facilitates horizontal gene transfer. This system, discovered in the context of multidrug resistance, is recognized in a clinical context for its role in allowing pathogens to adapt to the widespread use of antibiotics. Recent studies suggest that gene cassettes are common and encode functions relevant to many adaptive traits. To estimate the diversity of mobile cassettes in a natural environment, a molecular technique was developed to provide representative distributions of cassette populations at points within a sampling area. Subsequently, statistical methods analogous to those used for calculating species diversity were employed to assess the diversity of gene cassettes within the sample area in addition to gaining an estimate of cassette pool size. Results indicated that the number of cassettes within a \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape