Bacteria have been living on earth a few billion years longer than the Metazoans, and some of the bacteria evolved to live in very extreme environments such as hot thermal vents or ice. The mitochondria are essentially one lineage of bacteria that live within eukaryotic cells and within any sublineage of eukaryotes such as insects there is not so much diversity in nucleotide composition bias as there is across all bacteria.

The CoxI gene of insect mitochondria averages 69% A+T and 31% G+C while the CoxI gene of mammal mitochondria averages 58% A+T and 42% G+C. It is possible that the higher G+C content in mammals is due to a warm blooded lifestyle, but I am not sure if that is proven.

Anyway, the AT/GC ratio in a group of metazoans such as the insects or the mammals is quite stable and not a major factor to consider when barcoding species within such a lineage.

Bacteria have been living on earth a few billion years longer than the Metazoans, and some of the bacteria evolved to live in very extreme environments such as hot thermal vents or ice. The mitochondria are essentially one lineage of bacteria that live within eukaryotic cells and within any sublineage of eukaryotes such as insects there is not so much diversity in nucleotide composition bias as there is across all bacteria.

The CoxI gene of insect mitochondria averages 69% A+T and 31% G+C while the CoxI gene of mammal mitochondria averages 58% A+T and 42% G+C. It is possible that the higher G+C content in mammals is due to a warm blooded lifestyle, but I am not sure if that is proven.

Anyway, the AT/GC ratio in a group of metazoans such as the insects or the mammals is quite stable and not a major factor to consider when barcoding species within such a lineage.

Thanks Dr. Foley

Very interesting.

Hi Aref

GC content is a good indicator of primer binding and specificity. It will play a crucial role if you are making primers for specific alleles/genotypes/populations.