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Earth Notes - Lizard Parthenogenesis

Flagstaff, AZ – Earth Notes: For Whiptail Lizards, No Male Needed

In the world of genetics, variety isn't just the spice of life it's the cornerstone. Genetic variation helps species adapt to environmental changes like drought and disease. When each individual within a given species has a unique set of genes, each is equipped with a slightly different set of survival tools.

For most animals, sexual reproduction ensures genetic resiliency. Each parent contributes half the genetic material to a newborn, creating a new combination of genes each time egg and sperm unite.

But some animals from water fleas to sharks reproduce through a radically different process called parthenogenesis. In this process, females produce offspring from unfertilized eggs without any male genes.

Here in the Southwest, many species of whiptail lizards reproduce parthenogenetically. Recent research shows how one species, the Common Checkered Whiptail, avoids losing genetic information without sexual reproduction.

This whiptail, a fast desert runner, lives in parts of Texas, Colorado, and New Mexico. It derives from the union of two related whiptail species, giving it plenty of hybrid vigor from the start.

When producing eggs, the lizard employs a cell division process that ensures that each egg contains the same genetic information as its mother. There's no gain in genetic variability, but there's no loss either.

Parthenogenetic reproduction has its advantages. A single female can populate new habitat, and females don't need to expend energy searching for mates. How sustainable is this strategy? Ecologists debate that; meanwhile, the all-female population of Common Whiptail Lizards seems to be managing just fine without males.

-Alexandra Murphy