Logo image
Back
Pleistocene legacies in the contemporary population genetic structure of an acid-specialised crayfish, the threatened sand yabby Cherax robustus
Preprint

Pleistocene legacies in the contemporary population genetic structure of an acid-specialised crayfish, the threatened sand yabby Cherax robustus

Grace Smith, Tomer Ventura and Catherine Yule
Authorea , Vol.12 May 2026
Atypon
2026
DOI: https://doi.org/10.22541/authorea.15003163/v1
url
https://doi.org/10.22541/authorea.15003163/v1View
Preprint Version Open

Abstract

Following decades of clearing, fragmentation, and degradation of coastal heathlands in southeast Queensland, many endemic species are now threatened with extinction, including the vulnerable sand yabby Cherax robustus (Parastacidae), a freshwater crayfish restricted to 200km 2 of acidic wetlands. Dramatic fluctuations in the biogeography of these wetlands, particularly during the glacial cycles of the Pleistocene, likely shaped the distribution and genetic structure of acid-specialist species, yet their historic and contemporary connectivity remains poorly understood, despite these species being particularly sensitive to habitat fragmentation and environmental change. Here, we investigate the genetic structure of two island and two mainland C. robustus populations within peatlands using DArTseq next-generation DNA sequencing. Analysis of over 7,000 SNP markers indicates population divergence around the Pleistocene-Holocene boundary, with no detectable gene flow between most sites for between 5000 and 13000 years. Geographic proximity did not predict genetic connectivity due to persistent dispersal barriers such as K’gari’s central dune ridge and the Great Sandy Strait. Despite this long-term isolation, we found evidence of genetic erosion in only one population, which should continue to be monitored, however the effect appears natural, predating European arrival in Australia. Populations otherwise appear to have remained genetically healthy where suitable habitat persists, despite thousands of years of isolation. Evidently, sand yabbies are not naturally rare within these stable environments but have become vulnerable through anthropogenic pressures of habitat loss and degradation. The strong population structuring observed means that each population represents a unique genetic lineage, and each lost is irreplaceable. Protecting all remaining habitat and preventing any further degradation is therefore critical to the conservation of this species as well as the wider ecosystem.

Details

Metrics

1 Record Views
Logo image