Shifting ranges of two tree weta species (Hemideina spp.): competitive exclusion and changing climate
Article first published online: 4 DEC 2013
© 2013 John Wiley & Sons Ltd
Journal of Biogeography
Volume 41, Issue 3, pages 524–535, March 2014
How to Cite
Bulgarella, M., Trewick, S. A., Minards, N. A., Jacobson, M. J., Morgan-Richards, M. (2014), Shifting ranges of two tree weta species (Hemideina spp.): competitive exclusion and changing climate. Journal of Biogeography, 41: 524–535. doi: 10.1111/jbi.12224
- Issue published online: 11 FEB 2014
- Article first published online: 4 DEC 2013
- Massey University Research Grant. Grant Number: MURF2010
- Royal Society of New Zealand. Grant Number: PVT–601
- Biotic interactions;
- climate change;
- Hemideina ;
- mitochondrial DNA;
- New Zealand;
- range shifts;
- species range
Species' responses to climate change are likely to depend on their ability to overcome abiotic constraints as well as on the suite of species with which they interact. Responses to past climate change leave genetic signatures of range expansions and shifts, allowing inferences to be made about species' distributions in the past, which can improve our ability to predict the future. We tested a hypothesis of ongoing range shifting associated with climate change and involving interactions of two species inferred to exclude each other via competition.
The distributions of two tree weta species (Hemideina crassidens and H. thoracica) were mapped using locality records. We inferred the likely modern distribution of each species in the absence of congeneric competitors with the software Maxent. Range interaction between the two species on an elevational gradient was quantified by transect sampling. Patterns of genetic diversity were investigated using mitochondrial DNA, and hypotheses of range shifts were tested with population genetic metrics.
The realized ranges of H. thoracica and H. crassidens were narrower than their potential ranges, probably due to competitive interactions. Upper and lower elevational limits on Mount Taranaki over 15 years revealed expansion up the mountain for H. thoracica and a matching contraction of the low elevation limits of the range of H. crassidens. The observed nucleotide diversity in H. thoracica was consistent with a species that persisted in northern areas during Pleistocene glacial periods, from where it expanded at warmer times. In contrast, a two-tailed distribution of nucleotide diversity in H. crassidens was as expected for a species that expanded northwards during glacials and southwards during interglacials.
Range shifts resulting from climate change involve complex species interactions. Competition among related species is an important factor limiting realized ranges. In New Zealand, H. thoracica is likely to continue to displace H. crassidens as human-induced global warming proceeds.