[MARMAM] New paper on alliance formation in dolphins of Shark Bay

Simon Allen simon.allen at bristol.ac.uk
Thu Mar 25 07:02:43 PDT 2021

G’day Marmamers,

It seems that in at least some circumstances: the blood of the covenant is thicker than the water of the womb. We are pleased to draw to your attention to the latest (open access) paper out of Shark Bay Dolphin Research (www.sharkbaydolphins.org<http://www.sharkbaydolphins.org>).

In summary: We used (very) long-term behavioural and genetic data from well-known individual male dolphins in eastern Shark Bay, Western Australia, comparing a number of traits (including social bond strength, relatedness and age similarity) across two age periods: adolescence and adulthood. Social bond strength during adolescence predicted second-order alliance membership in adulthood, and males preferred others of similar age or older as second-order allies. Non-mating season social bond strength predicted first-order alliance partner preferences during mating season consortships with individual females, and relatedness did not influence partner choice at either alliance level.

This work represents the second data paper out of the stellar PhD by Livia Gerber under the supervision of Michael Krützen. The citation, link to the paper and abstract are as follows:

Gerber L, Wittwer S, Allen SJ, Holmes K, King SL, Wild S, Willems E, Connor RC, Krützen M (2021). Cooperative partner choice in multi-level dolphin alliances. Scientific Reports 11: 6901. https://www.nature.com/articles/s41598-021-85583-x

Investigations into cooperative partner choice should consider both potential and realised partners, allowing for the comparison of traits across all those available. Male bottlenose dolphins form
persisting multi-level alliances. Second-order alliances of 4–14 males are the core social unit, within which 2–3 males form first-order alliances to sequester females during consortships. We compared social bond strength, relatedness and age similarity of potential and realised partners of individual males in two age periods: (i) adolescence, when second-order alliances are formed from all available associates, and (ii) adulthood, when first-order allies are selected from within second-order alliances. Social bond strength during adolescence predicted second-order alliance membership in adulthood. Moreover, males preferred same-aged or older males as second-order allies. Within second-order alliances, non-mating season social bond strength predicted first-order partner preferences during mating season consortships. Relatedness did not influence partner choice on either alliance level. There is thus a striking resemblance between male dolphins, chimpanzees and humans, where closely bonded non-relatives engage in higher-level, polyadic cooperative acts. To that end, our study extends the scope of taxa in which social bonds rather than kinship explain cooperation, providing the first evidence that such traits might have evolved independently in marine and terrestrial realms.

Stay safe and sane.

All the best, Simon

Dr Simon J Allen
Mob: +44 (0) 77047 53101 [UK] / +61 (0) 416 083 653 [AU]
Email: Simon.Allen at bristol.ac.uk<mailto:Simon.Allen at bristol.ac.uk> / Simon.Allen at uwa.edu.au<mailto:Simon.Allen at uwa.edu.au>
Web: http://www.sharkbaydolphins.org
Twitter: @SimonJAllen1

Non-vertical transmission of a dolphin foraging innovation https://www.cell.com/current-biology/fulltext/S0960-9822(20)30756-9
Declines in dolphin survival and reproduction following a heatwave https://www.cell.com/action/showPdf?pii=S0960-9822%2819%2930217-9
Sexual displays involving marine sponges and alliance formation by Australian humpback dolphins http://rdcu.be/w3tL
Abundance and fidelity of dolphins to a trawl fishery https://www.nature.com/articles/s41598-017-05189-0<https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.nature.com%2Farticles%2Fs41598-017-05189-0&data=02%7C01%7C%7C58abd5f0ce074aaa92fe08d6a256357e%7Ceeea3199afa041ebbbf2f6e42c3da7cf%7C0%7C0%7C636874888971540847&sdata=1Kl8aDCzQ6KLGYrs18rdXAly7Bms0j%2BbqJpjSRmSOgY%3D&reserved=0>

“Believe me, my young friend, there is nothing–absolutely nothing–half so much worth doing as simply messing about in boats.” (Kenneth Grahame)
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