Patterns of regional endemism among New Zealand invertebrates

ABSTRACT

Biodiversity is unevenly distributed worldwide in terms of both species diversity and species endemism. Although centres of endemism are a conservation priority, both patterns and drivers of endemism are poorly understood in New Zealand. Here we explore whether invertebrate species distribution records in New Zealand represent the complete geographic range of species. We use distribution records of 2,322 invertebrate species to survey variation in range size and regional-endemism among 28 New Zealand regions, and explore the correlates of diversity and regional-endemism. Our data suggest patterns of regional-endemism in New Zealand invertebrates are not artefacts of sampling effort and the majority of species are not widespread. We found that endemism-score (which is a measure that corrects for species diversity) correlates positively with the relative size of the region three million years ago. Five variables (and their interactions) contributed to the relative level of invertebrate species endemism within a region (in a generalised linear model). Level of endemism tends to be lower in regions with greater geographic connectivity. This suggests that high levels of regional-endemism are not simply the product of the accumulation of species over time, but depends on the ability of a region to retain local species.

KEYWORDS:

• Diversity
• endemism
• extinction
• geology
• invertebrates of New Zealand
• range size

Acknowledgements

Matt Irwin, Lesley Essen and Jean Sanderson helped organise data. The research was aided by a Massey University Research Fund grant to M.M.R. and scholarships to B.T.S. from Massey University, the Brian Mason Scientific & Technical Trust, and the NZ Entomological Society. We appreciate the support of the Phoenix group (www.evolves.massey.ac.nz). The manuscript was improved by constructive criticism from Matt McGlone and two anonymous reviewers.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

Data associated with the paper from Fauna of New Zealand series https://www.landcareresearch.co.nz/publications/books/fauna-of-nz-series

ORCID

Mary Morgan-Richards http://orcid.org/0000-0002-3913-9814

Additional information

Funding

This work was supported by Massey University under Grant MURF 2014 & Doctoral scholarship to BTS; Brian Mason Scientific & Technical Trust and New Zealand Entomological Society.