The Elements of Evolution (33-1-5) Selfish Genes

 Selfish Genes

Selfish DNA poses a significant challenge to genome stability and organismal fitness in diverse eukaryotic lineages. It remains unclear why the observed evolutionary patterns conflict with theoretical expectations. ~ American geneticist Katie Clark

Despite the musical symphonic score of genic harmony, sour notes sometimes appear. Selfish genes do exist.

Selfish genetic elements are parasitic replicators that are specialists in ensuring their own transmission despite conferring no benefit, or even exacting a cost, on their bearers. They come in many flavors, such as transposable elements, segregation distorters, female meiotic drivers, and B chromosomes (or accessory chromosomes). ~ Indian microbiologist Nitin Phadnis

Self-centered mitochondrial DNA has been found in yeast, fungi, plants, and animals. Such parasitic sequences are deleterious to a cell or organism; yet they persist.

Selfish genes can preferentially insert themselves into the chromosomes of gametes, thus ensuring their propagation into the next generation. This genetic uppitiness violates the understood laws of inheritance first spelled out by Gregor Mendel.

Some alleles defy Mendel’s law and can increase their chances of being transmitted to the next generation by killing gametes that do not share the same alleles. ~ American biologists Antonis Roka & Dylan Shropshire

The few selfish genes that do exist demonstrate that genomes simply could not function if self-serving genes were the norm.