Modelling the emergence and stability of a vertically transmitted cultural trait in bottlenose dolphins
Highlights
► Sponging is a vertically, socially transmitted foraging behaviour in bottlenose dolphins. ► We investigated sponging stability and establishment with an individual-based model. ► Sponging is stably transmitted under certain conditions of learning fidelity and fitness benefits. ► Based on pairwise relatedness, sponging might have been present for at least 120 years.
Section snippets
The Sponging Behaviour
Despite the low likelihood predicted for vertically, socially transmitted behaviours to be established and maintained, at least one such behaviour (‘sponging’) has been established in each of the two gulfs of Shark Bay, Western Australia (Smolker et al. 1997; Mann et al. 2008; Bacher et al. 2010). A subset of the bottlenose dolphin population wears conical marine sponges on their rostra when apparently foraging along the seafloor (Smolker et al. 1997; Mann et al. 2008). This behaviour appears
The Model
We built an individual-based model of a diploid, sexually reproducing dolphin population in Matlab R2010a (MathWorks, Natick, MA, U.S.A.). Simulations were run and then compared to empirical results from the eastern and western gulfs of Shark Bay independently. The two populations are connected by high dispersal (number of migrants is much greater than one; Crow & Kimura 1970; Krützen et al. 2004a); however, the 110 km separation between the study sites has led to low, but significant, genetic
Sponger Stability
The simulations show that an initial proportion of 0.05 female spongers in the population does not change significantly, under certain conditions of learning fidelity of daughters born to spongers, and fitness benefits for spongers compared to nonspongers (Fig. 1). For example, if the learning fidelity equals 1, there cannot be any fitness costs for spongers otherwise sponging will disappear. With lower learning fidelity, progressively higher fitness benefits are required for stability of the
Discussion
Enquist et al. (2010) showed that conditions for stable vertical transmission from a single cultural parent exist, but are so restrictive as to be very unlikely. However, in this study, we used a different modelling approach to show that there are conditions that allow stable vertical social transmission from a single cultural parent, and that these conditions are representative of a natural population in which vertical transmission is supported by genetic data. Our stochastic model did not
Acknowledgments
This study was inspired by work to be published elsewhere and funded by Sea World Research and Rescue Foundation, National Geographic Society, Claraz-Schenkung, A.-H. Schultz Stiftung and Julius-Klaus Stiftung (grants to Michael Krützen, Lars Bejder and W.S.). We thank Janet Mann, Eric Patterson, Simon Allen and three anonymous referees for their helpful comments. A.M.K. was supported by a UNSW University International Postgraduate Award and by the E&ERC.
References (44)
- et al.
A comparison of association indices
Animal Behaviour
(1987) Microsatellite mutations in the germline: implications for evolutionary inference
Trends in Genetics
(2000)- et al.
Home range overlap, matrilineal and biparental kinship drive female associations in bottlenose dolphins
Animal Behaviour
(2010) - et al.
Developmental evidence for foraging traditions in wild bottlenose dolphins
Animal Behaviour
(2009) - et al.
2.6-Million-year-old stone tools and associated bones from OGS-6 and OGS-7, Gona, Afar, Ethiopia
Journal of Human Evolution
(2003) - Ackermann, C. 2008. Contrasting vertical skill transmission patterns of a tool use behaviour in two groups of wild...
- et al.
Genes or culture: are mitochondrial genes associated with tool use in bottlenose dolphins (Tursiops sp.)?
Behavior Genetics
(2010) - et al.
Habituated dolphins (Tursiops sp) in Western Australia
Journal of Mammalogy
(1985) - et al.
The bottlenose dolphin: social relationships in a fission–fusion society
- et al.
Observational conditioning of fear to fear-relevant and fear-irrelevant stimuli in rhesus monkeys
Journal of Abnormal Psychology
(1989)
An Introduction to Population Genetics Theory
Individual-based modeling of ecological and evolutionary processes
Annual Review of Ecology, Evolution, and Systematics
One cultural parent makes no culture
Animal Behaviour
Individual variation in prey selection by sea otters: patterns, causes and implications
Journal of Animal Ecology
Social learning in animals: empirical studies and theoretical models
BioScience
Introduction to Population Genetics
Social learning of diet and foraging skills by wild immature Bornean orangutans: implications for culture
American Journal of Primatology
Cultural drift: a primary process of culture change
Journal of Anthropological Research
Population structure in an inshore cetacean revealed by microsatellite and mtDNA analysis: bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia
Marine Mammal Science
‘O father: where art thou?’ Paternity assessment in an open fission-fusion society of wild bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia
Molecular Ecology
Cited by (16)
Integrating Genetic, Environmental, and Social Networks to Reveal Transmission Pathways of a Dolphin Foraging Innovation
2020, Current BiologyCitation Excerpt :However, due to the limited number of observations of those individuals, it may also be that we failed to capture some of the connections with other shellers in our dataset. In this context, it is worth noting that sponging appears to have arisen independently in each gulf of Shark Bay [48], highlighting the potential for complex behavioral innovations in this population. Along with sponging [6, 9, 49], shelling represents only the second reported case of tool use in dolphins.
Spatial consequences for dolphins specialized in foraging with fishermen
2018, Animal BehaviourCitation Excerpt :Given the extended parental care period, the cooperative foraging techniques may be passed down from mothers to offspring (Simões-Lopes et al., 2016). In these two aspects—innovation and vertical transmission—foraging with fishermen resembles the well-studied foraging specialization of dolphins that use marine sponges as tools in Shark Bay (e.g. Kopps et al., 2014; Kopps & Sherwin, 2012; Krützen et al., 2005). At the same time, dolphins learn from unrelated individuals, and this horizontal transmission can occur simultaneously with the tendency to interact more often with those individuals who forage in the same way.
Coviability as a scientific paradigm for an ecological transition, from an overview to a definition
2019, Coviability of Social and Ecological Systems: Reconnecting Mankind to the Biosphere in an Era of Global Change: The Foundations of a New Paradigm