News: Researchers from the University of Guelph (in Canada) found an unexpected link between chromosome sets in insects and the speed of mitochondrial genome evolution.
About Mitochondria Evolution in Insects
- Mitochondria evolved from bacteria and retain a small independent genome:
- Mitochondria originated when an ancient single-celled ancestor engulfed a bacterium, which later evolved into mitochondria.
- Over time, most bacterial genes moved to the nucleus, leaving a very small mitochondrial genome that produces energy for all cellular functions through adenosine triphosphate (ATP).
- Key Evolutionary Patterns in Insects
- Chromosome Systems in Insects
- Haploid condition: In some insects, males develop from unfertilised eggs and carry only one set of chromosomes, which makes them haploid.
- Diploid condition: Females in these insects develop from fertilised eggs and carry two sets of chromosomes, one from each parent, making them diploid.
- Haplo-diploid system: Ants, bees, and wasps follow this system, where females are diploid and males are haploid, and this method is called haplo-diploid sex determination.
- Diplo-diploid system: In this system, both males and females are diploid and differ only by their sex chromosomes, while both transmit one chromosome from each pair to their gametes.
- Mitochondrial DNA: Mitochondria are inherited only through females-
- Males do not pass mitochondria to offspring, even though mitochondrial function depends on interaction with nuclear genes.
- Unexpected evolutionary link: Despite maternal inheritance, species with haplo-diploid systems showed faster mitochondrial evolution than diplo-diploid species across insect orders.
- The COI Gene: The COI gene shows faster change in haplo-diploid species-
- Cytochrome c oxidase subunit I (COI) is a key mitochondrial protein, and its COI gene is in the mitogenome.
- Using consensus sequences for each insect family, researchers found that haplo-diploid species showed about 1.7 times more protein changes than diplo-diploid species.
- Chromosome Systems in Insects
- Implications for biodiversity tracking: Faster evolution of the COI gene in haplo-diploid insects means genetic barcodes may change unevenly, affecting accurate identification and monitoring of insect biodiversity.
