Polydactyly -- extra fingers or sometimes toes -- is one symptom of Ellis-van Creveld syndrome. The syndrome is commonly found among the Old Order Amish of Pennsylvania, a population that experienced the Founder Effect.
The Founder Effect is defined as a type of bottleneck, "a type of genetic drift describing the loss of the allelic variation that accompanies founding of a new population from a very small number of individuals.
I am utterly enamored with evolution. To me, it is not only the central concept of biology, but it is the single most interesting topic in all of science. Nothing fascinates me as much as evolution…
Mutations have an almost universally negative connotation (except in the context of superheros). When people hear the word, they instantly think of disabilities, bizarre disfigurements, and grotesque scenes from science fiction.
Natural selection is probably the most well known of the evolutionary mechanisms, and it is the one that most people think of when someone says, “evolution.” It is, however, often misunderstood, and people frequently fail to appreciate its complexity.
Sexual selection is really best understood as a type of natural selection because it operates off of the same three requirements: 1). The trait is heritable 2). The trait is variable 3). The variation affects individuals’ ability to pass genetic material on to the next generation.
Many people are under the false impression that evolution is always beneficial, but it can actually be quite harmful. This is especially true for evolution via genetic drift.
This simply refers to the movement of genetic information among populations (migration, for example, causes gene flow).