Pigmentation is a readily scorable and quantitative human phenotype, making it an excellent model for studying multifactorial traits and diseases. Convergent human evolution from the ancestral state, darker skin, towards lighter skin colors involved divergent genetic mechanisms in people of European vs. East Asian ancestry. It is striking that the European mechanisms result in a 10–20-fold increase in skin cancer susceptibility while the East Asian mechanisms do not. Towards the mapping of genes that contribute to East Asian pigmentation there is need for one or more populations that are admixed for ancestral and East Asian ancestry, but with minimal European contribution. This requirement is fulfilled by the Senoi, one of three indigenous tribes of Peninsular Malaysia collectively known as the Orang Asli. The Senoi are thought to be an admixture of the Negrito, an ancestral dark-skinned population representing the second of three Orang Asli tribes, and regional Mongoloid populations of Indo-China such as the Proto-Malay, the third Orang Asli tribe. We have calculated skin reflectance-based melanin indices in 492 Orang Asli, which ranged from 28 (lightest) to 75 (darkest); both extremes were represented in the Senoi. Population averages were 56 for Negrito, 42 for Proto-Malay, and 46 for Senoi. The derived allele frequencies for SLC24A5 and SLC45A2 in the Senoi were 0.04 and 0.02, respectively, consistent with greater South Asian than European admixture. Females and individuals with the A111T mutation had significantly lighter skin (p = 0.001 and 0.0039, respectively). Individuals with these derived alleles were found across the spectrum of skin color, indicating an overriding effect of strong skin lightening alleles of East Asian origin. These results suggest that the Senoi are suitable for mapping East Asian skin color genes.

Heterozygosityfor chromosomal arrangements was investigated in four species of the nasuta complex. D. sulfurigaster albostrigata, D. albomicans and D. kohkoa are highly polymorphic whereas D. puluua is monomorphic.Inversions were identified with the aid of photographic chromosome maps. The geographic distribution and frequencies of inversions detected and their possible phylogenies were discussed.

The genetic variation of Trigonobalanus verticillata , the most recently described genus of Fagaceae, was studied using chloroplast DNA sequences and AFLP fingerprinting. This species has a restricted distribution that is known to include seven localities in tropical lower montane forests in Malaysia and Indonesia. A total of 75 individuals were collected from Bario, Kinabalu, and Fraser's Hill in Malaysia. The sequences of rbc L , mat K, and three non-coding regions ( atp B -rbc L spacer, trn L intron, and trn L -trn F spacer) were determined for 19 individuals from these populations. We found a total of 30 nucleotide substitutions and four length variations, which allowed identification of three haplotypes characterizing each population. No substitutions were detected within populations, while the tandem repeats in the trn L -trn F spacer had a variable repeat number of a 20-bp motif only in Kinabalu. The differentiation of the populations inferred from the cp DNA molecular clock calibrated with paleontological data was estimated to be 8.3 MYA between Bario and Kinabalu, and 16.7 MYA between Fraser's Hill and the other populations. In AFLP analysis, four selective primer pairs yielded a total of 431 loci, of which 340 (78.9%) were polymorphic. The results showed relatively high gene diversity ( H S = 0.153 and H T = 0.198) and nucleotide diversity ( π S = 0.0132 and π T = 0.0168) both within and among the populations. Although the cp DNA data suggest that little or no gene flow occurred between the populations via seeds, the fixation index estimated from AFLP data ( F ST = 0.153 and N ST = 0.214) implies that some gene flow occurs between populations, possibly through pollen transfer.

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