The Alpine Fault biogeographic hypothesis revisited

Area of Science:

• Geosciences, Biogeography, Evolutionary Biology

Background:

• The New Zealand Alpine Fault, a major boundary between the Australian and Pacific Plates, has experienced significant right-lateral displacement.
• A notable distribution gap exists in central South Island taxa, traditionally attributed to glacial extirpation.
• This gap is often filled by closely related taxa across diverse ecological niches, including alpine and intertidal species.

Purpose of the Study:

• To address critiques of the Alpine Fault biogeographic hypothesis.
• To clarify misunderstandings regarding geological and biological aspects of the hypothesis.
• To demonstrate the hypothesis's validity as a multi-area statement.

Main Methods:

• Re-evaluation of geological data concerning fault inception and movement.
• Analysis of phylogenetic and track data for plant and animal taxa.
• Critique of previous interpretations of biogeographic disjunctions.

Main Results:

• Critiques by Wallis and Trewick (2001) are refuted by addressing misunderstandings of fault dynamics and taxon relationships.
• The Alpine Fault hypothesis is shown to be a robust multi-area biogeographic statement, not a simple two-area comparison.
• The central South Island distribution gap is explained by tectonic movement along the Alpine Fault.

Conclusions:

• The Alpine Fault's movement, not glacial events, is the primary driver of observed biogeographic disjunctions in New Zealand.
• The Alpine Fault biogeographic hypothesis is supported by a more nuanced understanding of geology and evolutionary biology.
• Further research into tectonic influences on biodiversity is warranted.