MORPHOLOGICAL CHARACTERISTICS, SEXUAL BEHAVIORS AND GENETIC INFORMATION OF HYBRIDS BETWEEN RHESUS Macaca mulatta AND LONG-TAILED MACAQUES M. fascicularis IN KHAO KHIEOW OPEN ZOO, THAILAND

Abstract

Rhesus (Macaca mulatta) and long-tailed (M. fascicularis) macaques are in the same fascicularis species group but live in the different climate zones. Rhesus macaques inhabit the cooler climate (15–35°N) while long-tailed macaques inhabit the warmer climate (20°N–10°S). The natural hybrid zone between these two species is 15–20°N, and difficult to study. This work focused on a hybrid population between these two species which was recently found in Khao Khieow Open Zoo, (KKZ; 13°21′N, 101°06′E) where a group of rhesus macaques was released into the habitat of feral long-tailed macaques about 20 years ago. Their morphological and genetic characteristics and sexual behaviors were evaluated. Photogrammetric method was used to assess %relative tail length (RTL) and contrast of the yellow pelage color (Cb*). %RTL, Cb* together with crown hair, cheek hair, and sex skin reddening were analyzed by Multiple Correspondence Analysis (MCA) and Agglomerative Hierarchical Cluster Analysis (AHCA) and categorized the KKZ macaques into 5 groups of long-tailed like (L4R0), hybrid (L3R1, L2R2 and L1R3), and rhesus-like (L0R4) macaques. Genetic discrimination of the two species and hybrids was done by STAT6 SNP analysis using PCR-RFLP technique. The 745 base pair fragment of STAT6 gene was digested with ApaI and gel electrophoresed which gave two, one and three band patterns that correspond to the G/G genotypes of long-tailed, A/A genotype of rhesus and A/G genotype of hybrid macaques, respectively. Of 118 KKZ samples, 6 (5%), 56 (47%), and 56 (47%) showed A/A, A/G, and G/G genotype, respectively, which were corresponded to their morphological characteristics. The frequency of G (long-tailed) allele in the population from the year 2006 to 2014 was significantly increased from 0.60 to 0.79, indicating a cline to long-tailed macaques. Nineteen adult females were selected from those 5 groups of KKZ macaques, and sexual behaviors including proceptivity, attractivity, and receptivity were collected by scan sampling method, 6–8 days/month from December 2011 to November 2012. All 5 monkey groups showed comparable patterns of sexual behaviors throughout the year. The patterns depicts breeding season with birth peak during March and May, especially in rhesus-like macaque group of which the receptivity was not seen during April and May. The results gained from this study are incongruent with previous reports indicating that rhesus macaques are strict seasonal breeders and long-tailed macaques are non-seasonal breeders. In regard to the morphological, genetic and behavioral studies of KKZ population, it confirms that the hybrids between rhesus and long-tailed macaques show intermediate characteristics between the two species and these characteristics are associated with each other.