The New Zealand biota: Historical background and new research.

New Zealand's origin as part of Gondwana, the composition of its ancestral biota, its geographic isolation for 80 million years, its tectonic history of changing shorelines and mountain building, and its changing climate, have all influenced the composition and distribution of its plant and animal communities, and thus its ecology and evolutionary biology. Recent DNA-sequencing studies combined with palaeogeographic analysis suggest that an Oligocene marine transgression had a major genetic bottle-neck effect on the biota and, together with recent advances in avian biogeography and paleontology, are leading to new hypotheses on the origin of many bird groups.