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The date of historical domestication of dogs has been pushed back to between 15,000–30,000 years ago (estimates vary), a time when hunter-gatherer societies predominated in northern Europe and central Asia. We present insights from evolutionary behavioural ecology suggesting that wolves may have been “tricked” by their social evolution into contributing to the success of prehistoric human families or tribes. Four different wolves (one observed in great detail, as reported in recent book) that were raised by human families exhibited cooperative behaviours that protected their human “pack members.” Such hereditary altruistic behaviours may have been transferred by descent to the first dogs, which helped our ancestors hunt large animals and fight against other human tribes and wild carnivores. We hypothesize that the first need in domestication was for less aggressive wolf behaviour, within the wolf and human coevolution of the cooperative family or tribe that used wolves to increase their competitive fitness advantages.

In otariids, mother's recognition by pups is essential to their survival since females nurse exclusively their own young and can be very aggressive towards non-kin. Antarctic fur seal, Arctocephalus gazella, come ashore to breed and form dense colonies. During the 4-month lactation period, females alternate foraging trips at sea with suckling period ashore. On each return to the colony, females and pups first use vocalizations to find each other among several hundred conspecifics and olfaction is used as a final check. Such vocal identification has to be highly efficient. In this present study, we investigated the components of the individual vocal signature used by pups to identify their mothers by performing playback experiments on pups with synthetic signals. We thus tested the efficiency of this individual vocal signature by performing propagation tests and by testing pups at different playback distances. Pups use both amplitude and frequency modulations to identify their mother's voice, as well as the energy spectrum. Propagation tests showed that frequency modulations propagated reliably up to 64m, whereas amplitude modulations and spectral content greatly were highly degraded for distances over 8m. Playback on pups at different distances suggested that the individual identification is a two-step process: at long range, pups identified first the frequency modulation pattern of their mother's calls, and other components of the vocal signature at closer range. The individual vocal recognition system developed by Antarctic fur seals is well adapted to face the main constraint of finding kin in a crowd.

Abstract Background Recent developments in high-throughput methods of analyzing transcriptomic profiles are promising for many areas of biology, including ecophysiology. However, although commercial microarrays are available for most common laboratory models, transcriptome analysis in non-traditional model species still remains a challenge. Indeed, the signal resulting from heterologous hybridization is low and difficult to interpret because of the weak complementarity between probe and target sequences, especially when no microarray dedicated to a genetically close species is available. Results We show here that transcriptome analysis in a species genetically distant from laboratory models is made possible by using MAXRS, a new method of analyzing heterologous hybridization on microarrays. This method takes advantage of the design of several commercial microarrays, with different probes targeting the same transcript. To illustrate and test this method, we analyzed the transcriptome of king penguin pectoralis muscle hybridized to Affymetrix chicken microarrays, two organisms separated by an evolutionary distance of approximately 100 million years. The differential gene expression observed between different physiological situations computed by MAXRS was confirmed by real-time PCR on 10 genes out of 11 tested. Conclusions MAXRS appears to be an appropriate method for gene expression analysis under heterologous hybridization conditions.

The vocal signature in a species of the genus Eudyptes, the macaroni penguin is examined to find whether voice signature would extend to other nest-building penguins. The findings indicate an original and simple signature system in macaroni penguins.

Mate choice is particularly important in slow-breeding species, like king penguins (Aptenodytes patagonicus), because a poor choice of mate can not be corrected for a year or more. King penguin males are not territorial, so females are unable to assess a males quality based on his territory and therefore must use another cue. Immune strength may be reflected by ornamental bill or feather color, traits that are especially revealing in penguins because the birds have no opportunity to feed during molt. We tested the hypothesis that plumage color in the king penguin reflects an individuals immunocompetence, by presenting birds with a phytohaemaglutinin (PHA) challenge and measuring the T-cell lymphocyte response 24 hours later. We captured 53 unpaired adult males on Possession Island, in the Crozet Archipelago (46[degrees]25S, 51[degrees]45E), then measured ornamental colors on the upper breast, the auricular patch, and the beak spot. To assess immune strength, we measured footweb thickness before, and 24 hours after, injecting a 500 [micro]l bolus of distilled water containing 500 [micro]l of PHA into the footweb. All males showed a response to the PHA challenge, with a mean (+/- SE) swelling of 2.27 (+/- 0.12) mm, and all color measures showed substantial variation. Only breast hue showed a significant relationship with footweb swelling ([r.sub.s]=-0.33, n=53, p=0.015). Breast hue varies from a yellow/orange color (lower hue values) to a rusty brown color (higher hue values), so this result indicates that birds with less-darkly colored breast patches showed the strongest response to challenge with PHA. We conclude that ornamental color does reflect immune strength in the king penguin, although the various ornaments seem to have different signal contents that may represent differences in physiological trade-offs or differences in absorption of the pigment underlying these colors.