Final Answer:
Mitochondrial DNA (mtDNA) exhibits greater genetic diversity than the Y chromosome in human populations due to its maternal inheritance and lack of recombination. Maternal transmission ensures the accumulation of mutations over generations, contributing to increased diversity. The absence of recombination events further maintains and enhances this diversity in mtDNA.
Step-by-step explanation:
In human populations, the disparity in genetic diversity between mitochondrial DNA (mtDNA) and the Y chromosome arises from their distinct inheritance patterns and molecular characteristics. MtDNA is exclusively inherited maternally, passed down from mother to offspring. During fertilization, the mitochondria in the sperm are typically excluded, leading to a lack of paternal contribution to mtDNA. This maternal inheritance results in a continuous lineage of mitochondrial genomes through the maternal line, allowing for the accumulation of genetic variations over generations without recombination.
Contrastingly, the Y chromosome is inherited paternally and experiences recombination during meiosis, where genetic material is exchanged between homologous chromosomes. Recombination contributes to a reduction in genetic diversity on the Y chromosome compared to mtDNA. The absence of recombination in mtDNA, coupled with its higher mutation rate, further accentuates its diversity. Mutations in mtDNA accumulate steadily over time, providing a record of maternal ancestral lineages.
In summary, the greater genetic diversity observed in mtDNA compared to the Y chromosome in human populations is attributed to the combination of maternal inheritance and the absence of recombination in mtDNA, facilitating the preservation and accumulation of genetic variations along maternal lineages over evolutionary timescales.
Complete Question:
Why is there generally greater mitochondrial DNA (mtDNA) diversity compared to Y chromosome diversity in human populations?