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Australian spiny mountain crayfish and their temnocephalan ectosymbionts: an ancient association on the edge of coextinction?
journal contribution
posted on 2023-05-18, 21:06 authored by Hoyal Cuthill, JF, Sewell, KB, Cannon, LRG, Michael CharlestonMichael Charleston, Lawler, S, Littlewood, DTJ, Olson, PD, Blair, DAustralian spiny mountain crayfish (Euastacus, Parastacidae) and their ecotosymbiotic temnocephalan flatworms (Temnocephalida, Platyhelminthes) may have co-occurred and interacted through deep time, during a period of major environmental change. Therefore, reconstructing the history of their association is of evolutionary, ecological, and conservation significance. Here, time-calibrated Bayesian phylogenies of Euastacus species and their temnocephalans (Temnohaswellia and Temnosewellia) indicate near-synchronous diversifications from the Cretaceous. Statistically significant cophylogeny correlations between associated clades suggest linked evolutionary histories. However, there is a stronger signal of codivergence and greater host specificity in Temnosewellia, which co-occurs with Euastacus across its range. Phylogeography and analyses of evolutionary distinctiveness (ED) suggest that regional differences in the impact of climate warming and drying had major effects both on crayfish and associated temnocephalans. In particular, Euastacus and Temnosewellia show strong latitudinal gradients in ED and, conversely, in geographical range size, with the most distinctive, northern lineages facing the greatest risk of extinction. Therefore, environmental change has, in some cases, strengthened ecological and evolutionary associations, leaving host-specific temnocephalans vulnerable to coextinction with endangered hosts. Consequently, the extinction of all Euastacus species currently endangered (75%) predicts coextinction of approximately 60% of the studied temnocephalans, with greatest loss of the most evolutionarily distinctive lineages.
History
Publication title
Proceedings of the Royal Society of London: Biological SciencesVolume
283Issue
1831Article number
20160585Number
20160585Pagination
1-10ISSN
0962-8452Department/School
School of Natural SciencesPublisher
Royal Soc LondonPlace of publication
6 Carlton House Terrace, London, England, Sw1Y 5AgRights statement
Copyright 2016 The Author(s)Repository Status
- Restricted