Spatial partitioning of morphological and genetic variation in the New Zealand falcon (Falco novaeseelandiae) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, Palmerston North
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Date
2014
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Massey University
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Abstract
The New Zealand falcon (Falco novaeseelandiae) is a medium sized falcon endemic to New Zealand. New Zealand falcons have a flexible ecology, inhabiting a variety of habitats including bush, coastlines, mountains, open tussock land, farm land and exotic pine forests. Phylogenetic analysis suggests the New Zealand falcon is not sister to or related closely to any species in either Australia or South America as proposed in earlier research. Neither does it appear to fit within in any other major group such as the heirofalcons or the kestrels.
The New Zealand falcon is currently defined as a single variable species with three recognised morphs or races that are referred to as the Bush, Eastern and Southern these appear to differ in colour and size. This proposal was established in 1977 and has since become generally accepted. However, there are alternative hypotheses as to how this variation is size may be spatially partitioned across the New Zealand landscape. A reassessment of the morphometric data in New Zealand falcons is needed to identify how this morphological variance is distributed. Specifically, to identify any evidence for three distinct morphs, in contrast to the alternative hypothesis of a gradient in size consistent with Bergmann’s rule. The analysis suggests that there is little support for the occurrence of three morphs of New Zealand falcon; instead, there is a distinct difference in size between the North and South Islands. There is some evidence of a gradual change corresponding to latitude but this appears to be minimal. Mean wing lengths are significantly longer in male and female falcons in the South Island compared to those in the North Island.
To understand if the size difference between the North and South Islands is an effect of an adaptive response and to examine the extent of gene flow occurring between the two islands a study of neutral genetic markers is needed. Evidence of genetic structure was tested for among New Zealand falcon populations using nuclear and mitochondrial data. Little support for any population structuring was identified. Evidence from this analysis suggests that the falcons are responding to particular environmental conditions within each island resulting in a change in size, however high juvenile dispersal may be preventing the partitioning of gene flow between the North and South Islands.
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Keywords
New Zealand falcon, Falco novaeseelandiae, New Zealand falcon phylogeny, New Zealand falcon genetics, Polymorphism, New Zealand falcon morphology