In this study heteroplasmy genotyping of green sea turtles,
Chelonia mydas, using high throughput sequencing (HTS) was used to better
understand SNP and mtSTR in the mitochondrial genome and its variation within
individuals across generations. HTS allows for the observing of mtDNA on the
repeating the D-loop, which is not under strong selective pressure.
Heteroplasmy is the existence of mitochondrial DNA (mtDNA) variant within a
cell. Mitochondrial DNA is 0.001% of genomic content and due to oxidative phosphorylation,
mutations that occur in mtDNA are directly associated to inherited diseases. Since
heteroplasmy deals with variation in mtDNA the haplotypes passed down to
generations, the mtDNA comes from maternal inheritance. Population sizes green
turtles will determine the variation in haplotypes especially depending on the
amount of female turtle populations. The maternal inheritance of mtDNA has a
large influence on heteroplasmy due to the number of mitochondria passed, the
DNA inherited and mutations along with it. Due to mtDNA being only maternally
inherited and the low population sizes of green turtles, the passed down mtDNA
has low genetic diversity, low mutation rates, and low rates of new generations.
A shift in haplotypes from maternal inheritance will signal genetic
bottlenecking during oogenesis meaning heteroplasmy will increase with larger
populations and decrease in diversity with smaller populations. This study
found haplotypes in individuals of green turtles in foraging grounds more than
nesting sights meaning there mixing of stocks and the HTS revealed that
heteroplasmy is low in frequency among these individuals.
https://www.nature.com/articles/s41598-019-56918-6.pdf
https://pubmed.ncbi.nlm.nih.gov/22578655/
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