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Ethnicity, gene flow, and population subdivision in Limón, Costa Rica
1Department of Anthropology. University of South Florida. Tampa, Florida 33620, USA. madrigal@luna.cas.usf.edu
American Journal of Physical Anthropology
|February 15, 2001
Summary
Ethnicity in Limón, Costa Rica, has maintained distinct genetic populations. Analysis of surnames and blood samples revealed limited gene flow, confirming ethnic groups remained separate breeding populations.
Area of Science:
- Population genetics
- Human evolution
- Anthropology
Background:
- Gene flow and genetic structure are influenced by social and historical factors.
- Understanding ethnic group distinctiveness requires analyzing genetic exchange patterns.
- Costa Rica's Limón province hosts diverse ethnic groups with unique histories.
Purpose of the Study:
- To investigate the impact of ethnicity on gene flow between Hispanic-Limonense and Afro-Limonense populations in Costa Rica.
- To determine if ethnic divisions have acted as barriers to genetic exchange.
- To assess the genetic distinctiveness of these two groups.
Main Methods:
- Collected blood samples and surname data from 375 individuals.
- Analyzed two surnames per individual to ascertain parental ethnicity.
- Computed admixture estimates and F(st) values using established formulas and the ADMIX.PAS program.
Main Results:
- Hispanic-Limonense group: 58.66% European, 33.83% Amerindian, 7.51% African ancestry.
- Afro-Limonense group: 10.47% European, 13.57% Amerindian, 75.95% African ancestry.
- F(st) values (0.00558 for Hispanic, 0.05137 for Afro-Limonense) suggest greater genetic drift in the Afro-Limonense group, possibly due to isolation.
Conclusions:
- The two ethnic groups in Limón, Costa Rica, have remained genetically distinct breeding populations.
- Ethnicity has acted as a significant barrier to gene flow between these groups.
- The findings highlight the role of historical isolation in maintaining genetic differentiation.