Biomedical subjects

Ben D Moore

Publications and source records attributed to Ben D Moore.

4 recordsLinked to original sources

PubMed2005

Tree use by koalas in a chemically complex landscape.

Although defence against herbivores is often argued to be the main action of plant secondary metabolites (PSMs), very few examples have demonstrated that intraspecific variation in PSM concentrations influences foraging by wild vertebrate herbivores. Experiments with captive animals often indicate that PSM concentrations influence how much herbivores eat from individual plants, but these experiments do not replicate the subtle trade-offs in diet selection faced by wild animals, which must avoid predators and extremes of weather, interact with conspecifics, and achieve a balanced, nutritious diet, while avoiding intoxication by PSMs. We characterized the foliar chemistry of every tree from two Eucalyptus species available to a population of koalas (Phascolarctos cinereus) and considered rates of tree visitation over a ten-year period. We show that visitation rate was most strongly influenced by tree size, but that koalas also visited trees less frequently if the foliage contained either high concentrations of deterrent PSMs known as formylated phloroglucinol compounds, or low concentrations of nitrogen. Consequently, plant chemistry restricts the use of trees by this herbivore, and thus limits the food available to koalas and potentially influences koala populations.

Animals↗

PubMed2005

Eucalyptus foliar chemistry explains selective feeding by koalas.

The koala is the quintessential specialist herbivore, feeding almost exclusively on Eucalyptus foliage. Consequently, the limitations imposed on the koala's diet by plant defences indicate the extent to which evolutionary adaptations allow mammalian herbivores to circumvent such defences. We tested whether a recently discovered group of plant secondary metabolites, the formylated phloroglucinol compounds (FPCs), deters koalas from feeding on some eucalypt foliage. We found that captive koalas ate less foliage in a single night from trees with high FPC concentrations. Individual trees also differ in the types of FPC they possess, but for a given eucalypt species, most FPCs were similarly effective deterrents. Two closely related and sympatric eucalypt species could be clearly separated by the amounts that koalas ate from each; however, this difference could not be explained by total FPC concentrations alone. We suggest, that in this case, the presence of a distinct type of FPC deters koala herbivory on the less palatable species, and may have facilitated the evolutionary divergence of these species. We conclude that plant defences probably play an important role in determining the distribution and abundance of koalas.

Animals↗

PubMed2005

Plant secondary metabolites and vertebrate herbivores--from physiological regulation to ecosystem function.

Plant secondary metabolites can constrain the diet of vertebrates and these effects can flow through to community dynamics. Recent studies have moved beyond attempting to correlate diet choice with secondary metabolite profiles and instead focus on mechanisms that animals use to detect toxins and to regulate their intake and absorption. These include molecularly determined taste specificity, serotonin-mediated learning and the control of toxin absorption by permeability-glycoproteins. Focus on the detoxification pathways employed by specialist and generalist herbivores has facilitated explicit tests of the long-standing hypothesis that detoxification rates limit feeding. Understanding the molecular basis of differences amongst species in their tolerance of plant secondary metabolites opens many opportunities for understanding the evolutionary history of interactions between vertebrates and their food plants.

Animals↗

PubMed2004

Antiherbivore chemistry of Eucalyptus-cues and deterrents for marsupial folivores.

Formylated phloroglucinol compounds (FPCs) are the single most important factor determining the amount of foliage that marsupial folivores eat from individual Eucalyptus trees. Folivores need to recognize which trees contain FPCs if they are to avoid them and forage efficiently, they are challenged by great diversity in the types and quantities of FPCs present, even within eucalypt species. We investigated the relationship between FPCs and terpenoids in species with both simple and complex FPC profiles and found strong positive correlations between terpenes generally, and several monoterpenes in particular, and FPCs. Terpene cues also indicated qualitative differences in trees' FPC profiles. We describe significant qualitative and quantitative variation in FPCs in several species that are important food sources for marsupial folivores. New discoveries include the fact that macrocarpals occur as two major, distinct groups and several new dimeric acylphloroglucinols from Eucalyptus strzeleckii. These patterns add to the chemical complexity of the foraging environment for folivores.

Animals↗