Abstract:
Marron, Cherax tenuimanus and Cherax cainii (Austin) being two of the largest
freshwater crayfish species in the world, are highly sought after by recreational anglers
and form the basis of an expanding aquaculture industry in western Australia. This study
investigates the potential for using mitochondrial protein coding gene regions for
studying geographic patterns of genetic divergence among marron populations. Partial
sequences of Cytochrome b (Cyt b) (471 bp) and Cytochrome Oxidase I (COI) (600bp)
gene regions were obtained from marron representing 13 populations from southwest
Western Australia, and from Kangaroo Island, South Australia. Two data sets that
derived from Cyt b and COI gene regions showed significant phylogenetic signal. Within
C. cainii, twelve COI and ten Cyt b haplotypes were observed from the 14 locations with
little intrapopulation diversity and with few haplotypes found at more than one location.
Average divergence between species is Average divergence within C. cainii is 0.64% for
Cyt b and 1.58% for COI gene region. Average divergence between C. cainii and C.
tenuimanus is 12.17% and 5.89% for Cyt b and COI gene regions respectively. The
phylogenetic analyses indicated that the two marron species, C. tenuimanus and C. cainii
are quite divergent and provide evidence for geographic fragmentation in C. cainii. In C.
cainii, the most significant phylogenetic structure was among samples from Western
Australia’s south coast river systems compared to the samples from the northern part of
the species distribution which showed much less diversity. The study indicates that both
the COI and Cyt b gene regions will be valuable for studying geographic population
structure within the widespread species, C. cainii.
