For animals living in mixed-sex social groups, females who form strong social bonds with other females live longer and have higher offspring survival [1-3]. These bonds are highly nepotistic, but sometimes strong bonds may also occur between unrelated females if kin are rare [2, 3] and even among postdispersal unrelated females in chimpanzees and horses [4, 5]. Because of fundamental differences between the resources that limit reproductive success in females (food and safety) and males (fertilizations), it has been predicted that bonding among males should be rare and found only for kin and among philopatric males [6] like chimpanzees [7-9]. We studied social bonds among dispersing male Assamese macaques (Macaca assamensis) to see whether males in multimale groups form differentiated social bonds and whether and how males derive fitness benefits from close bonds. We found that strong bonds were linked to coalition formation, which in turn predicted future social dominance, which influenced paternity success. The strength of males' social bonds was directly linked to the number of offspring they sired. Our results show that differentiated social relationships exert an important influence on the breeding success of both sexes that transcends contrasts in relatedness.

Background: Bengal tiger Panthera tigris tigris the National Animal of India, is an endangered species. Estimating populations for such species is the main objective for designing conservation measures and for evaluating those that are already in place. Due to the tiger's cryptic and secretive behaviour, it is not possible to enumerate and monitor its populations through direct observations; instead indirect methods have always been used for studying tigers in the wild. DNA methods based on non-invasive sampling have not been attempted so far for tiger population studies in India. We describe here a pilot study using DNA extracted from faecal samples of tigers for the purpose of population estimation.

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BackgroundNon-invasively collected samples allow a variety of genetic studies on endangered and elusive species. However due to low amplification success and high genotyping error rates fewer samples can be identified up to the individual level. Number of PCRs needed to obtain reliable genotypes also noticeably increase.MethodsWe developed a quantitative PCR assay to measure and grade amplifiable nuclear DNA in feline faecal extracts. We determined DNA degradation in experimentally aged faecal samples and tested a suite of pre-PCR protocols to considerably improve DNA retrieval.ResultsAverage DNA concentrations of Grade I, II and III extracts were 982pg/µl, 9.5pg/µl and 0.4pg/µl respectively. Nearly 10% of extracts had no amplifiable DNA. Microsatellite PCR success and allelic dropout rates were 92% and 1.5% in Grade I, 79% and 5% in Grade II, and 54% and 16% in Grade III respectively. Our results on experimentally aged faecal samples showed that ageing has a significant effect on quantity and quality of amplifiable DNA (p<0.001). Maximum DNA degradation occurs within 3 days of exposure to direct sunlight. DNA concentrations of Day 1 samples stored by ethanol and silica methods for a month varied significantly from fresh Day 1 extracts (p<0.1 and p<0.001). This difference was not significant when samples were preserved by two-step method (p>0.05). DNA concentrations of fresh tiger and leopard faecal extracts without addition of carrier RNA were 816.5pg/µl (±115.5) and 690.1pg/µl (±207.1), while concentrations with addition of carrier RNA were 49414.5pg/µl (±9370.6) and 20982.7pg/µl (±6835.8) respectively.ConclusionsOur results indicate that carnivore faecal samples should be collected as freshly as possible, are better preserved by two-step method and should be extracted with addition of carrier RNA. We recommend quantification of template DNA as this facilitates several downstream protocols.