Natural Selection and the Rock Pocket Mouse

Flashcards reviewing the key concepts of natural selection, genetic mutations, and adaptation based on Michael Nachman's study of the rock pocket mouse.

Where is the Valley Of Fire located, and what caused its dark landscape?

It is located in New Mexico and was formed by volcanic eruptions about $1,000$ years ago that spewed a lava river more than $40$ miles long.

Why do dark rock pocket mice on the lava flow still have white underbellies?

Predators attack from above, so there is no selective pressure for dark fur on their bellies.

What evolutionary mechanism drives the change in fur color among the rock pocket mouse population in the Valley Of Fire?

Predators, which are primarily visual hunters like owls, coyotes, foxes, rattlesnakes, and hawks, weed out the mice that do not match their background.

How is a genetic mutation defined in the context of the lecture?

A mutation is a change in the chemical letters that make up genes, caused by a copying error during cell division.

Are genetic mutations inherently good or bad for an organism?

Mutations are neither inherently good nor bad; whether they are favored, rejected, or neutral depends entirely on the environmental conditions the organism inhabits.

What specific genetic difference was discovered between light and dark rock pocket mice from the same desert region?

A difference of $4$ chemical letters in a gene called MC1R, which controls the amount of dark pigment in hair follicles.

If dark fur gives pocket mice a $1\%$ competitive advantage, how long does it take for $95\%$ of the population to become dark?

It takes about $1,000$ years, starting from $1\%$ dark mice in the population.

How long does it take for $95\%$ of the pocket mouse population to turn dark if the dark color provides a $10\%$ advantage?

It takes only $100$ years.

What common misconception about evolution is countered by the rock pocket mouse study?

The misconception that evolution is an entirely random process; while mutations occur at random, natural selection non-randomly sorts winners from losers.

What did Michael Nachman discover when examining dark rock pocket mice from different lava flows hundreds of miles apart?

The dark mice on different lava flows evolved dark fur through completely different genetic changes in different genes, despite looking almost identical.