Australian spiny mountain crayfish and their temnocephalan ectosymbionts: an ancient association on the edge of coextinction?

Hoyal Cuthill, Jennifer F. and Sewell, Kim B. and Cannon, Lester R. G. and Charleston, Michael A. and Lawler, Susan and Littlewood, D. Timothy J. and Olson, Peter D. and Blair, David (2016) Australian spiny mountain crayfish and their temnocephalan ectosymbionts: an ancient association on the edge of coextinction? Proceedings of the Royal Society B: Biological Sciences, 283 (1831). p. 20160585. ISSN 0962-8452 Online ISSN 1471-2954 DOI https://doi.org/10.1098/rspb.2016.0585

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Abstract

Australian 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.

Item Type:	Article
Uncontrolled Keywords:	2016AREP; IA70;
Subjects:	04 - Palaeobiology
Divisions:	04 - Palaeobiology 08 - Green Open Access
Journal or Publication Title:	Proceedings of the Royal Society B: Biological Sciences
Volume:	283
Page Range:	p. 20160585
Identification Number:	https://doi.org/10.1098/rspb.2016.0585
Depositing User:	Sarah Humbert
Date Deposited:	25 May 2016 17:29
Last Modified:	12 Sep 2019 09:38
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3667

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