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Participants: Dr Matthew Symonds (PI), Dr Glenn Tattersall (Brock University, Canada), Prof Andrew F Bennett
Aims and Background Climate influences many aspects of animal biology and diversity, including their body shape. Theory suggests that appendages such as legs, tails, ears etc., will be smaller in animals living in colder environments in order to reduce heat loss (a pattern known as Allen’s rule). In birds, beaks play an underappreciated, but vital, role in regulating body temperature, and there is evidence that beak size changes with climatic gradients. This project will conduct a global examination of the geographic patterns of inter- and intra- specific variation in the size and shape of bird beaks in order to answer the questions “Is there are global pattern to beak size in birds and is it related climate?” Using comparative morphological, ecological and phylogenetic data, the project will assess whether certain bird lineages exhibit stronger climatic effects on beak size, and if so, determine what are the ecological attributes (e.g. resource use, habitat, life history) of these lineages that make them more susceptible to these effects.
Scientific significance and innovation: The project’s significance lies in its investigation of how climate drives change in an important physical aspect of a major lineage of animals. Bird beaks are iconic structures in evolutionary biology. Many studies have shown how the selection on these appendages is intimately associated with foraging, competition, vocalisation and sexual selection, but their thermoregulatory role is rarely considered. The project will elucidate clearly the role of climate and thermoregulation in driving the size and shape of these characteristic body parts. More generally, the effect of climate on appendage size is a neglected field of study in evolutionary ecology. Allen’s rule was proposed in 1877, but its effect has never been considered in a wide context. This is surprising because it has the capacity to explain both global patterns of diversity in body shape in birds. Geographic variation is an important part of intraspecific diversity and, since it is typically linked to selective forces, is important in speciation. In birds, many of the subspecific classifications are based on variation in body part size, which may actually be the result of Allen’s rule. Therefore, understanding the bases of these clines is essential to correctly identifying threatened species and for drawing up management plans for their conservation.
Potential national benefit and strategic alignment with the aims of the CIE: The key benefit from the research will be a gain in understanding of how climate drives the evolution of animal morphology through its investigation of bird beak size. As such, this research links to the National Research Priority: An Environmentally Sustainable Australia (Priority Goal: Responding to climate change and variability). The vision of the CIE is to address the fundamental question of how life reacts to change on both short and long time scales. The analysis of the way bird beaks vary in response to climate differences on an evolutionary timescale squarely fits with this vision. Likewise, the combination of ecological and evolutionary approaches to examine population and interspecific responses to ambient environment reflects the research approach of the CIE.