Koalas: talvez o mais seletivo dos marsupiais

terça-feira, novembro 30, 2010

Koala Bears May Be the 'Pickiest' Marsupials Around

ScienceDaily (Nov. 29, 2010) — Koalas may be the pickiest marsupials around: They evolved to feed almost exclusively on the leaves of Eucalyptus trees, and they are highly selective when it comes to which species and even which individual trees they visit. When the furry leaf-eater settles on a particular tree, it relies on a number of factors, including taste, to make its selection. In a study published in the November issue of Ecology, a journal of the Ecological Society of America (ESA), researchers used koala feeding preferences to design a new method that could help ecologists and conservationists map habitats.

A mother koala with its baby joey. (Credit: iStockphoto/Craig Dingle)

Ben Moore and colleagues from the Australian National University and the Macaulay Land Use Research Institute in Scotland collected and analyzed leaves from all the trees available to koalas in a Eucalyptus woodland using a near-infrared spectroscopic model. To define "palatability" in koala terms, the researchers tested leaves on captive koalas and recorded how much they ate: They found that the koalas ate less foliage when it contained lots of lipid-soluble phenolic chemicals known as formylated phloroglucinol compounds (FPCs). The researchers then tracked koala tree visits in a Eucalyptus woodland to show that tree preferences of wild koalas could be predicted using the taste preferences of the captive koalas. The researchers also determined the chemical composition of the trees' leaves and other factors such as tree size and neighborhood quality, or how attractive each tree's neighbors were to koalas.

Read more here/Leia mais aqui: Science Daily


Moore, Ben D., Ivan R. Lawler, Ian R. Wallis, Colin M. Beale, and William J. Foley. 2010. Palatability mapping: a koala's eye view of spatial variation in habitat quality. Ecology 91:3165–3176. [doi:10.1890/09-1714.1]


Palatability mapping: a koala's eye view of spatial variation in habitat quality

Ben D. Moore1,4, Ivan R. Lawler2,5, Ian R. Wallis1, Colin M. Beale3,6, and William J. Foley1

1Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT 0200 Australia

2School of Earth and Environmental Sciences, James Cook University of North Queensland, Douglas, Queensland 4811 Australia

3Ecology Group, Macaulay Land Use Research Institute, Aberdeen AB158QH United Kingdom

Ecologists trying to understand the value of habitat to animals must first describe the value of resources contained in the habitat to animals and, second, they must describe spatial variation in resource quality at a resolution relevant to individual animal foraging. We addressed these issues in a study of koalas (Phascolarctos cinereus) in a Eucalyptus woodland. We measured beneficial and deterrent chemical characteristics as well as the palatability of trees using a near-infrared spectroscopic model based on direct feeding experiments. Tree use by koalas was influenced by tree size and foliar quality but was also context-dependent: trees were more likely to be visited if they were surrounded by small, unpalatable trees or by large, palatable trees. Spatial autocorrelation analysis and several mapping approaches demonstrated that foliar quality is spatially structured in the woodland at a scale relevant to foraging decisions by koalas and that the spatial structure is an important component of habitat quality.

Keywords: associational defense, Australian Eucalyptus woodland, formylated phloroglucinol compounds, generalized additive mixed modeling, habitat quality, koala, NIRS, patch use, Phascolarctos cinereus, plant secondary metabolites,spatial autocorrelation

Received: September 18, 2009; Revised: February 11, 2010; Accepted: March 3, 2010; Revised: March 25, 2010

4Present address: Ecology Group, Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB158QH United Kingdom. E-mail: b.moore@macaulay.ac.uk

5Present address: Department of the Environment, Water, Heritage and the Arts, GPO Box 787, Canberra, ACT 2601 Australia.

6Present address: Department of Biology (Area 18), P.O. Box 373, University of York, YO105YW United Kingdom.