Whiptail Lizards

News Flash! All Women, No Men Required.

Apparently the Feminist Movement began WAY before the 1800’s. The Aspidoscelis’ sexual reproduction, or whiptail lizard, is not the norm. It is parthenogenetic, meaning their eggs develop into embryos without fertilization. When it comes to this planet’s sexual activity and offspring, UNDISPUTEDLY things are not black and white!

NGS Picture Id:2208767In sexual reproduction — the way many life-forms procreate — each parent provides half an offspring’s chromosomes. Over generations, this mating and procreating shuffles the DNA deck, giving sexual reproducers a genetic diversity that helps them adapt to changing environments.

By contrast, asexual reproducers — some 70 vertebrate species and many less complex organisms — “use all the chromosomes they have” to solitarily produce offspring that are genetic clones, says molecular biologist Peter Baumann. Because those organisms are genetically identical, they’re more vulnerable. A disease or an environmental shift that kills one could kill all.

Here’s the muddling grey to rigid black and white: In the case of the whiptail lizards, genus Aspidoscelis, they are all females. Before their eggs form, Baumann’s study found, the females’ cells gain TWICE the usual number of chromosomes — so the eggs get a full chromosome count and genetic variety and breadth (known as heterozygosity) rivaling that of a sexually reproduced lizard.

Why does this occur? Because hundreds of thousands of years ago, Baumann says, lizards of the genus Aspidoscelis had “a hybridization event” — that is, females of one species broke form and mated with males of another species. Those outlier liaisons gave whiptails robust heterozygosity, which has been preserved by the identical replication — essentially, cloning — that occurs in asexual reproduction. It’s a genetic-diversity advantage that today’s females still enjoy and propagate! No, not human females… whiptail lizards! But the same sort of sexual diversity in Homo sapiens might be a great and much-needed change, huh?  😉

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from the November 2016 National Geographic magazine, by Patricia Edmonds

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