East African origins for Madagascan chickens as indicated by mitochondrial DNA

Abstract

The colonization of Madagascar by Austronesian-speaking people during AD 50-500 represents the most westerly point of the greatest diaspora in prehistory. A range of economically important plants and animals may have accompanied the Austronesians. Domestic chickens (Gallus gallus) are found in Madagascar, but it is unclear how they arrived there. Did they accompany the initial Austronesian-speaking populations that reached Madagascar via the Indian Ocean or were they late arrivals with Arabian and African sea-farers? To address this question, we investigated the mitochondrial DNA control region diversity of modern chickens sampled from around the Indian Ocean rim (Southeast Asia, South Asia, the Arabian Peninsula, East Africa and Madagascar). In contrast to the linguistic and human genetic evidence indicating dual African and Southeast Asian ancestry of the Malagasy people, we find that chickens in Madagascar only share a common ancestor with East Africa, which together are genetically closer to South Asian chickens than to those in Southeast Asia. This suggests that the earliest expansion of Austronesian-speaking people across the Indian Ocean did not successfully introduce chickens to Madagascar. Our results further demonstrate the complexity of the translocation history of introduced domesticates in Madagascar.

Keywords: Madagascar; chicken; dispersal; human migration; mitochondrial DNA.

Figure 1.

Frequency distribution of chicken mitochondrial DNA haplogroup in the region under study (blue, haplogroup D; white, haplogroup E; grey, other haplogroups) with geographical location and sample size noted. Sample localities are Azerbaijan (AZR), Bangladesh (BLH), Burma (BUR), India (IND), Iran (IRA), Irian Jaya (IRJ), Java (JAV), Kalimantan (KAL), Kenya (KEN), Korea (KOR), Laos (LAO), Madagascar (MAD), Malawi (MLW), Maluku (MLK), Nigeria (NIG), Nusa Tenggara (NUS), Pacific (PAC; Fiji, Solomon and Vanuatu), Philippines (PHL; Luzon, Visayas and Mindanao), Saudi Arabia (SAU), South China (SC), Sri Lanka (SRI), Sudan (SUD), Sulawesi (SUL), Sumatra (SUM), Thailand (THA), Turkmenistan (TRK), Vietnam (VIE) and Zimbabwe (ZIM).

Figure 2.

Multidimensional scaling plots (MDS) for pairwise population Slatkin's linearized F_ST for (a) 3128 chickens from Asia (orange), Africa (red), ISEA (green) and the Pacific (blue) using all haplogroups. (b) 1081 haplogroup D chickens from the same regions. Azerbaijan, Iran, Korea, Saudi Arabia, Sudan and Turkmenistan are not present in plot B because they do not contain haplogroup D lineages. See figure 1 for locality abbreviations.

Figure 3.

Median-joining network depicting the relationship of D haplotypes of chickens from East Africa and Madagascar (blue), South Asia (black) and Indonesia (green) using all observed D haplotypes regardless of frequency. Stars mark the position of the Madagascan samples. Inferred haplotypes are indicated by small red dots.

Figure 4.

Median-joining (MJ) network of mtDNA-CR D haplotypes observed in Madagascar (purple), Africa (blue), South Asia (brown) and Indonesia (green) excluding most haplotypes represented by one sample. The circle sizes are proportional to the haplotype frequencies and the length of the lines corresponds to the number of mutations connecting haplotypes.