Abstract:
The New Zealand coastline and marine environment is a diverse place and presents
plenty of dispersal obstacles to many of the organisms that live there. This thesis
investigates the phylogeography of one of the most common fish species around the
coast of New Zealand, the endemic wrasse Notolabrus celidotus, using the
mitochondrial DNA control region and compares genetic variability to another common
New Zealand wrasse, Notolabrus fucicola in a local setting. These species are part of a
tribe of temperate fish, the pseudolabrines, which can be found throughout the South
and North-West Pacific. The phylogeny of this tribe was also analysed using the
mitochondrial 16S gene to investigate the relationships among the New Zealand
pseudolabrines and to those species elsewhere. The results suggest that pseudolabrines
from mainland New Zealand are closely related and are likely to have originated from
southern Australia while species from the Kermadec Islands and other northern islands
are more closely related to the species of eastern Australia. The Notolabrus and
Pseudolabrus genera should be reviewed to remedy paraphyly of Pseudolabrus.
Furthermore, N. celidotus shows no population structuring throughout its range and
appears to be rapidly expanding. Genetic variability was similar for both N. celidotus
and N. fucicola. The results suggest that the pseudolabrine tribe has made multiple
migrations to New Zealand where Notolabrus celidotus was able to spread around the
three main islands and, likely facilitated by a long planktonic larval duration, was able
to maintain high gene flow among populations.
