What can we learn from selfish loci that break Mendel’s law?

S. E. Zanders,  PLOS Biology,  20:e3001700. 2022.

Mendel’s law of segregation provides a critical foundation for genetic inquiry It is not, however, without exceptions Historically, 2 such exceptions (sex chromosome linkage and chromosome missegregation in meiosis) were used by Drosophila geneticists to help demonstrate that genes are carried on chromosomes Looking forward, modern geneticists interested in understanding the mechanisms of heredity have much to learn from additional exceptions to Mendel’s law In particular, selfish genes that break Mendel’s law of segregation to gain a transmission advantage into the next generation are likely to be oversized contributors to shaping the process of sexual reproduction These selfish genes exploit reproduction such that a given selfish locus is transmitted to more than half of the offspring produced by an organism There are a variety of selfish DNAs, but here I will focus on transposable elements and drive loci as examples Transposable elements can generate novel copies of themselves using copy and paste or cut and paste mechanisms Importantly, transposable elements are selected to mobilize in the germline as that allows new copies to be passed on to subsequent generations Drive loci preferentially bias their own transmission such that a driver+ /driver− heterozygote will pass the driver+ allele to more than half of its viable progeny Drivers are diverse and can act during meiosis, gametogenesis, or post-fertilization Both transposable elements and drivers are found throughout eukaryotes, including humans

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