Calves as social hubs: dynamics of the social network within sperm whale units

It is hypothesized that the primary function of permanent social relationships among female sperm whales (Physeter macrocephalus) is to provide allomothers for calves at the surface while mothers make foraging dives. In order to investigate how reciprocity of allocare within units of sperm whales facilitates group living, we constructed weighted social networks based on yearly matrices of associations (2005–2010) and correlated them across years, through changes in age and social role, to study changes in social relationships within seven sperm whale units. Pairs of association matrices from sequential years showed a greater positive correlation than expected by chance, but as the time lag increased, the correlation coefficients decreased. Over all units considered, calves had high values for all measured network statistics, while mothers had intermediate values for most of the measures, but high values for connectedness and affinity. Mothers showed sharp drops in strength and connectedness in the first year of their new calves' lives. These broad patterns appear to be consistent across units. Calves appeared to be significant nodes in the network of the social unit, and thus provide quantitative support for the theory in which communal care acts as the evolutionary force behind group formation in this species.

[1]  M. Bekoff,et al.  Wild Justice Redux: What We Know About Social Justice in Animals and Why It Matters , 2012 .

[2]  S. Brosnan.  An evolutionary perspective on morality , 2011 .

[3]  V. Nanjundiah.  Evolution of social behaviour , 2010 .

[4]  Edouard Machery,et al.  The Evolution of Morality , 2015 .

[5]  Tim Clutton-Brock,et al.  Cooperation between non-kin in animal societies , 2009, Nature.

[6]  Luke Rendell,et al.  Who Cares? Between-group variation in alloparental caregiving in sperm whales , 2009 .

[7]  Hal Whitehead,et al.  SOCPROG programs: analysing animal social structures , 2009, Behavioral Ecology and Sociobiology.

[8]  Luke Rendell,et al.  Overlapping and matching of codas in vocal interactions between sperm whales: insights into communication function , 2008, Animal Behaviour.

[9]  H. Whitehead,et al.  Heterogeneous social associations within a sperm whale, Physeter macrocephalus, unit reflect pairwise relatedness , 2008, Behavioral Ecology and Sociobiology.

[10]  David Lusseau,et al.  Incorporating uncertainty into the study of animal social networks , 2008, Animal Behaviour.

[11]  Hal Whitehead,et al.  Analyzing Animal Societies: Quantitative Methods for Vertebrate Social Analysis , 2008 .

[12]  H. Whitehead,et al.  Population estimate and inter-island movement of sperm whales, Physeter macrocephalus, in the Eastern Caribbean Sea , 2023, J. Cetacean Res. Manage..

[13]  D. Lusseau.  Evidence for social role in a dolphin social network , 2006, Evolutionary Ecology.

[14]  D. Krakauer,et al.  Policing stabilizes construction of social niches in primates , 2006, Nature.

[15]  M. Nakamichi.  Behavioral characteristics of old female Japanese monkeys in a free-ranging group , 1984, Primates.

[16]  Elisabeth Slooten,et al.  IMPACTS OF COMMERCIAL WHALE WATCHING ON MALE SPERM WHALES AT KAIKOURA, NEW ZEALAND , 2006 .

[17]  K. N. Laland,et al.  Social structure and co-operative interactions in a wild population of guppies (Poecilia reticulata) , 2006, Behavioral Ecology and Sociobiology.

[18]  M. Taborsky,et al.  Contingent movement and cooperation evolve under generalized reciprocity , 2005, Proceedings of the Royal Society B: Biological Sciences.

[19]  J. Mann,et al.  Cultural transmission of tool use in bottlenose dolphins. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[20]  Sebastian Bonhoeffer,et al.  Evolution of cooperation by generalized reciprocity , 2005, Proceedings of the Royal Society B: Biological Sciences.

[21]  Jessica C Flack,et al.  Play signaling and the perception of social rules by juvenile chimpanzees (Pan troglodytes). , 2004, Journal of comparative psychology.

[22]  R. Sapolsky,et al.  A Pacific Culture among Wild Baboons: Its Emergence and Transmission , 2004, PLoS biology.

[23]  H. Whitehead,et al.  Social organization of female sperm whales and their offspring: constant companions and casual acquaintances , 1991, Behavioral Ecology and Sociobiology.

[24]  H. Whitehead.  Sperm Whales: Social Evolution in the Ocean , 2003 .

[25]  V. Braithwaite,et al.  The Long-Term Benefits of Human Generosity in Indirect Reciprocity , 2002, Current Biology.

[26]  S. Mesnick.  Genetic relatedness in sperm whales: Evidence and cultural implications , 2001, Behavioral and Brain Sciences.

[27]  Peter L. Tyack,et al.  Cetacean societies : field studies of dolphins and whales , 2001 .

[28]  L. McLoughlin,et al.  PRELIMINARY STATEMENT , 2001 .

[29]  T. J. Roper,et al.  Activity synchrony and social cohesion: a fission-fusion model , 2000, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[30]  Jessica C. Flack,et al.  Any animal whatever. Darwinian building blocks of morality in monkeys and apes , 2000 .

[31]  H. Whitehead.  Variation in the visually observable behavior of groups of Galapagos sperm whales , 1999 .

[32]  O. Leimar,et al.  Sex–biased dispersal in sperm whales: contrasting mitochondrial and nuclear genetic structure of global populations , 1999, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[33]  Hal Whitehead,et al.  Techniques for Analyzing Vertebrate Social Structure Using Identified Individuals: Review and Recommendations , 1999 .

[34]  K. Gibson,et al.  Mammalian social learning : comparative and ecological perspectives , 1999 .

[35]  H. Whitehead,et al.  Sperm whale social units : variation and change , 1998 .

[36]  M. N,et al.  The Dynamics of Indirect Reciprocity , 1998 .

[37]  H. Whitehead,et al.  Patterns of kinship in groups of free-living sperm whales (Physeter macrocephalus) revealed by multiple molecular genetic analyses. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[38]  H. Whitehead.  Babysitting, dive synchrony, and indications of alloparental care in sperm whales , 1996, Behavioral Ecology and Sociobiology.

[39]  H. Whitehead,et al.  Polymorphic microsatellites from sperm whales and their use in the genetic identification of individuals from naturally sloughed pieces of skin , 1996, Molecular ecology.

[40]  O. Leimar,et al.  The evolution of cooperation in mobile organisms , 1993, Animal Behaviour.

[41]  H. Whitehead,et al.  Assessing the stock identity of sperm whales in the eastern equatorial Pacific , 1993 .

[42]  R. Payne,et al.  RESTRICTABLE DNA FROM SLOUGHED CETACEAN SKIN; ITS POTENTIAL FOR USE IN POPULATION ANALYSIS , 1992 .

[43]  M. Pavelka.  Sociability in Old Female Japanese Monkeys: Human versus Nonhuman Primate Aging , 1991 .

[44]  H. Whitehead,et al.  OBTAINING SKIN SAMPLES FROM LIVING SPERM WHALES , 1990 .

[45]  M. Nowak,et al.  The evolution of stochastic strategies in the Prisoner's Dilemma , 1990 .

[46]  Charlotte K. Hemelrijk,et al.  Models of, and tests for, reciprocity, unidirectionality and other social interaction patterns at a group level , 1990, Animal Behaviour.

[47]  H. Whitehead,et al.  Observations on the composition and behaviour of groups of female sperm whales near the Galapagos Islands , 1989 .

[48]  Hal Whitehead,et al.  Distinctive vocalizations from mature male sperm whales (Physeter macrocephalus) , 1988 .

[49]  Steven J. Schwager,et al.  A comparison of association indices , 1987, Animal Behaviour.

[50]  P. C. Lee,et al.  Allomothering among African elephants , 1987, Animal Behaviour.

[51]  N. Burley,et al.  Social Evolution, Robert Trivers. Benjamin/Cummings, Menlo Park, Calfornia (1985), xvii, +462, Price £19.95 in U.K., $18.95 in U.S.A. (paperback) , 1986 .

[52]  Gary D. Schnell,et al.  Statistical comparison of proximity matrices: applications in animal behaviour , 1985, Animal Behaviour.

[53]  M. Hauser,et al.  Old age and its behavioral manifestations: a study on two species of macaque. , 1984, Folia primatologica; international journal of primatology.

[54]  W. Hamilton,et al.  The evolution of cooperation. , 1984, Science.

[55]  S. Hrdy.  "Nepotists" and "Altruists": The Behavior of Old Females Among Macaques and Langur Monkeys , 1981, Other Ways of Growing Old.

[56]  J. Quadagno,et al.  Other Ways of Growing Old: Anthropological Perspectives , 1981 .

[57]  P. Best.  Social Organization in Sperm Whales, Physeter macrocephalus , 1979 .

[58]  P. Waser.  Postreproductive survival and behavior in a free-ranging female mangabey. , 1978, Folia primatologica; international journal of primatology.

[59]  R. D. Alexander,et al.  The evolution of social behavior , 1974 .

[60]  N. Mantel.  The detection of disease clustering and a generalized regression approach. , 1967, Cancer research.

[61]  A. Gouldner.  THE NORM OF RECIPROCITY: A PRELIMINARY STATEMENT * , 1960 .