Research Interests of the Owens Lab:

We study the ecological and genetic basis of diversification, using empirical, molecular and comparative methods. This work uses approaches developed in the fields of ecology, behaviour, quantitative genetics and evolution. Most of our study organisms are vertebrates, particularly birds.

Figure 1: Heron Island, where we have a long-term research project on the Capricorn silvereye (Zosterops lateralis chlorocephala). Heron Island is a subtropical island at the southern tip of the Great barrier Reef off the East coats of Australia. The local race of silvereye is up to 40% larger than it's mainland counterpart (Z.l.familiaris).

(1) Speciation, sexual signals and colouration

Why do closely-related species often have such very different sexual displays and sexual ornaments? The traditional explanation is that interspecific variation in sexual displays represent 'reproductive character displacement', that is an adaptation to prevent hybridisation with the other species. However, equally plausible explanations include the hypotheses that (i) closely-related species have different signals because they live in subtly different signalling environments, or (ii) racial differences are due to neutral genetic mechanisms such as drift or founder events, or (iii) differences in sexual displays evolve through cultural evolution via sexual imprinting. We test these conflicting hypotheses using a combination of marker-based estimates of genetic covariance, field-based experiments, mate choice trials in the laboratory, quantitative measurement of reflectance spectra, and comparative approaches.

We also have related projects on the function of carotenoid-based colouration, fluorescence in parrots, and UV-reflective colouration.

(2) Divergence in ecology and morphology in island-dwelling birds

Island-dwelling races are often very different from their mainland counterparts, in terms of morphology, behaviour and ecology. Insular races of passerine birds, for instance, are often much larger than their mainland counterparts, whereas insular races of non-passerine are generally larger than expected. The traditional explanation for these sorts of shifts are based on selection acting of feeding behaviour due to changes in the level of interspecific competition. Again, however, there are several other explanation including other forms of selection and neutral mechanisms. We are currently testing these competing hypotheses using the island-dwelling birds of the South West Pacific and the North Atlantic, using neutral genetic marker-based methods to estimate quantitative genetic parameters such as heritability and genetic covariance.

	Figure 2: Two races of white-eye from Norfolk Island in the South West Pacific. The bird on the left is Zosterops tenuirostris while the bird on the left is the Norfolk Island race of Zosterops lateralis. We are studying the processes that have led to such divergence in body size (and behaviour).
Figure 3: Heron Island silvereye, like many island-dwelling birds this race is unusually tame.

(3) Hotspots, biodiversity and extinction

Why have different lineages suffered such very different evolutionary fates, in terms of rates of extinction and cladogenesis? One set of explanations suggests that differences between lineages in macroevolutionary parameters is simply due to chance, with there being no consistent differences in terms of intrinsic biological characteristics between 'winners' and 'losers'. Most of our work suggests that this is not the case, as we have identified a series of robust ecological correlates of variation in both extinction-rate and species-richness. The ongoing challenge is to demonstrate empirically why traits such as ecological specialisation is associated with patterns of extinction and speciation. We are now extending our work to macrecological questions, such as the latitudinal gradient in species richness, the ecological basis of 'biodiversity hotspots', and geographic variation in rates of genetic recombination. This new work combines traditional phylogeny-based comparative methods with new approaches to bioinfomatic mining of genomic databases.

Figure 4: Lord Howe Island rails. This species is a conservation classic, having been brought back from the brink of extinction by a captive-breeding program. We are studying why some lineages, such as the rails, are so vulnerable to extinction.

Selected Publications: (Click here for full Publication List)

Bennett, P.M. & Owens, I.P.F. (2002) Evolutionary Ecology of Birds: Life History, Mating System and Extinction. Oxford University Press. PUBLISHER'S WEBPAGE

Arnold, K.E., Owens,I.P.F. & Marshall, N.J. (2002) Fluorescent signalling in parrots. Science 295, 92.PDF COPY

Clegg,S.M, Degnan, S.M., Kikkawa, J., Moritz, C., Estoup, A. & Owens, I.P.F. (2002) Genetic consequences of sequential founder events in a natural system. Proc. Nat. Acad. Sci. USA 99, 8127-8132. PDF COPY: COMMENTARY

Fisher, D.O. & Owens, I.P.F. The comparative method in conservation biology: extinction, introduction and invasion. Trends in Ecology & Evolution (2004), 19, 391-398. PDF COPY

Owens, I.P.F. (2002) Sex differences in mortality rates. Science 297, 2008-2009. PDF COPY

Owens, I.P.F. and Bennett, P.M. (2000) Ecological basis of extinction risk in birds: habitat loss versus human persecution and introduced predators. Proc. Nat. Acad. Sci. USA 97, 12144-12148. PDF COPY

Owens, I.P.F., Bennett, P.M. & Harvey, P.H. (1999) Species-richness among birds: body size, life history, sexual selection or ecology? Proceedings of the Royal Society of London B 266, 933-940. PDF COPY

Scott, S.N., Clegg, S.C., Kikkawa, J. & Owens, I.P.F. (2003) Morphological shifts in island-dwelling passerines: the roles of generalist foraging and niche expansion. Evolution  57, 2147-2156. PDF COPY

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