Results
Data about mitochondrial and Y chromosome markers were collected from 501 people from St. Lucia, Grenada, St. Thomas, Jamaica, St. Kitts, St. Vincent, Dominica, and Trinidad to determine the influence of compulsory migration, separation, and admixture on genetic variety in African-Caribbean populations.
Data analyses of mitochondrial and Y chromosomes showed that Africans in the islands did not lose any genetic diversity and genetic composition after movements. There was variation in the genetic structure across the islands, which the researchers attributed to isolation, variations in sources, the number of slaves, colonization history, and the decline of the indigenous people. About ten percent of the population consisted of a non-African mitochondrial haplogroup. On the other hand, Y chromosome admixture analyses revealed that about 30 percent of Caribbean populations originated from Europeans.
Data were presented in four tables. Table 1 presented sample size, gene average, nucleotide, and diversity compositions from the mtDNA haplogroup. Table 2 captured data related to sample size, haplotype diversity, standard deviation, and frequencies of DYS 287 insertion. Table 3 presented Y chromosome admixture estimates for each island while Table 4 captured the number of participants allocated to each mtDNA haplogroup. There was also a figure map to show the Caribbean islands that were used in the research. While tables and figures were used to present summaries of data, there were elaborate explanations for each table to provide clear accounts of research findings for readers.
Discussion
The study aimed to fill the knowledge gap in the poorly studied biological consequences in African-Caribbean populations and therefore, it contributed to the comprehension of nature and elements of diversity among Africans in the islands.
Findings by these researchers seemed to concur with other previous studies. For instance, they acknowledged small sample sizes of mitochondrial and Y chromosomal loci but the researchers showed that diversity and admixture outcomes were similar to other previous studies by Miljkovic-Gacic et al. 2005; Parra et al. 1998; and Saha & Samuel, 1987 involving African Diaspora.
There was reduced diversity noted in Dominica, which could have occurred due to small samples or some challenges within the community. To support this observation, the researchers noted that the International Data Base of the US Bureau of the Census 2006 also found that Dominica was the least densely populated among all the islands.
Results indicated the variation in the DYS 287 Alu insertion between islands, which was a clear indicator for the African Y chromosome haplogroup E (DE). Similar findings were established in previous studies conducted by Quintana-Murci et al. 1999; Y chromosome Consortium, 2002; and Hammer, 1994.
The results further showed that variations were distributed within the islands’ Caribbean populations. Although the distribution was small, nevertheless it was significant. The researchers further noted that MtDNA haplogroup analysis showed that many Caribbean populations’ maternal ancestry was Africa. Salas et al. (2002) noted similar findings as cited by the researchers.
Conclusion
The study concluded that African genetic distribution within Caribbean islands had stronger links with various colonial activities and specific islands’ demographic characteristics. Major European populations that could have shaped and influenced genetic compositions in the islands included British, French, and Spanish. Overall, the study showed that the observed levels of genetic diversity across Caribbean islands were similar in African populations and this could help in understanding the diverse populations among African Diaspora.