| The group stability mechanism is the breach of researching the survival strategy of animals, where the mating system and foraging strategy are the two key factors of the group stability mechanism. In Sichuan snub-nosed monkey (Rhinopithecus roxellana), they both are inseparable to the social organization. The basic unit of R. roxellana society consist of one adult male, serveral adult female and their offsprings. The resident male of a unit is often replaced, but the female is relatively stable. This kind of harem is meaningful to the stability of units and troop, and becomes a key issue in researching the group stability mechanism of R. roxellana.On the other hand, kinship is one of the key factors of mating system and social organization of animal. How can female monkeys in a same unit live together long and stable? In order to answer this question, and test if relatedness influence the harem of R. roxellana, and test if relatedness influence the dispersal of females between units, I collect the noninvasive genetic samples from monkeys in West Ridge Troop on the basis of individual identification. The pairwised relatedness coefficient is obtained from microsatellite genotype data, and the relatedness coefficient of different categories classified by unit and gender are compared to study how does the relatedness influence the harem system of R. roxellana, dispersal strategy and social organization. The main results are as follows:1. Compared the effectiveness of method of moment and maximum likelihood in estimating relatedness. By computer simulation, Lynch&Ritland (1999) estimator yield least variance in comprehensive consideration of parent-offspring, full-sibs, half-sibs and unrelated, the variance of corresponding relationship is0.0236,0.0344,0.0350and0.0256. It meet the demands of this study and is selected for estimating relatedness.2.131adult samples and86individuals were collected from West Ridge Troop in ZhouZhi National Nature Reserve by3study periods (in year2005,2008and2011). Fifty-two polymorphic microsatellite loci were segregated from144reported loci in non-human primate using samples from serveral locations in Qinling mountains. And18most polymorphic loci from which were select for this study. Genotype of each individual at each loci was obtain from at least two positive amplification to make sure the correct genotype rate reaches99%. The number of alleles is3.8889±0.7370(mean±SD), observed heterozygosity is0.6179±0.0883, expected heterozygosity is0.6261±0.0601, PIC is0.5572±0.0703, effective number of alleles is2.7514±0.4933, inbreeding coefficient Fls=0.0118±0.1214. All loci were according to the Hardy-Weinberg Equilibrium except D13s321which were exclude from further analysis. These result indicate that the genetic diversity of WRT was in a high level, while the inbreeding level is low.3. According the genotype data, the pairwised relatedness coefficient was calculated. The individual dyads were classified into6categories according to the unit and gender (female-female within unit, female-female within troop, female-male within unit, female-male within troop, male-male within troop, all dyads). By comparing the median of relatedness in different categories, I found that the relatedness of females within unit is significantly different from that that within troop (P<0.0001, Z=4.7170), and the mean relatedness of females within unit is higher than that within troop (F-F in OMU r=0.0673, F-F in Troop r=-0.0049). This result indicate significant kin selection in female monkeys in unit organization, and female kins are prefer to live in a same unit.4. By comparing the destiny and candidate units of dispersing female monkeys, I found female selective disperse into the unit consist her female relatives (P=0.0056, Z=-2.7685), but the selectivity of resident male was not significant (P=0.9274, Z=0.0911).5. Fisher’s test was performed to test whether the genotypes and alleles in males and females were drawn from the same distribution. And the results illustrate that their distribution were significantly different (alleles:χ2=59.64, P=0.0042; genotypes: χ2=58.03, P=0.0063). And extract G-test was performed for each locus, and I found the genotypes and alleles in males and females were drawn from the different distribution at four loci (D7s2204, D19s248, TPOX and D16s540, a=0.05). Which showed there are a large proportion in one of the two gender were migrants, and integrating the field observation data, I infer that the male individuals are more possible to dispersal among troops, and AMU may be the bridge of gene flow between troops. |
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