Micro-Evolution

All animals are the result of macro-evolution. Micro-evolution only relates to a small portion of a species evolutionary timeline. Since most evolution is slow and gradual, we as humans commonly can only observe a small amount of changes in our life time. House sparrows have adapted to the climate of North America, mosquitoes have evolved in response to global warming, and insects have evolved resistance to our pesticides. These are all examples of micro-evolution.

Micro-Evolution vs. Macro-Evolution

The only difference between the two is the amount of changes that have occurred. It’s the same as a little amount of candy and a lot of candy, the difference is only in the amount. Since our DNA changes a slight bit with every single offspring the addition of changes is constant and a little will become a lot over time. When the amount changes add up enough that the animal stops resembling the species it derived from it is called macro-evolution. Micro-evolution is just evolution on a small scale.

Birds

Birds are very adaptive, resulting in great varieties of each species. All of the 14 species of finches on the Galápagos Islands evolved from one ancestral species, which arrived from South America two million years ago, to adapt to its surroundings and competition for food. The woodpecker finch's beak evolved to drill holes in trees and the vampire finch evolved to drink blood from other birds.

Researchers from Princeton University observed a species of ground finch in the Galápagos Islands. Within less than just two decades the finches haves evolved smaller beaks and most of these changes happened within just one generation. The evolution from medium to small beaks was a direct result of competition for food with large ground finch (arrived in 1982) and a clear display of natural selection. These finches adapted by evolving even smaller beaks that are more suitable for breaking open smaller seeds that the larger and dominant finch don’t bother with.

Dogs

Today canines include 35 species that vary almost as much as domestic dogs do, from stumpy Brazilian bushdogs to lanky maned wolves. Canines live everywhere from the tundra to rainforest, on every continent except Antarctica. Because of this we see a larger variety in the appearance of canines as they have each evolved traits to adapt to each area. Crossbreeding can be considered micro-evolution. It is the process of breeding 2 animals or plants, often with the intention of creating offspring that share the traits of both parent lineages. Most domestic dogs are the result of crossbreeding.

Hesperocyonines evolved in North America about 40 million years ago and looked like a cross between a weasel and a fox. The hesperocyonines became extinct about 15 million years ago but gave rise to all others "dogs."

Borophagines, largest canine ever, began flourishing about 34 million years ago and were hyena-like animals with huge jaw muscles and sturdy teeth. They became extinct about 3 million years ago.

Canines includes the extinct dire wolf and all living species of canines. This group occurred only in North America until 7 million years ago, when some species crossed a land bridge to Asia.

Polar Bears

We have a well documented resources of fossil transistions that lead us to the Polar Bear's first existance. About 100,000 to 250,000 years ago a number of brown bears, simular to grizzly bears, made their way up north. Due to the harsh artic conditions, over the next 20,000 years the brown bear evolved to have a thicker coat to fight the cold and lighter fur to blend in with it's surroundings. Polar bears are still evolving and adapting to thier surroundings, thier teeth are different and more addaptive than that of their ancestors from just a few thousand years ago. Kurten, a specialist in the history of bears mentions "From the early Ursus minimus of 5 million years ago to the late Pleistocene cave bear, there is a perfectly complete evolutionary sequence without any real gaps. The transition is slow and gradual throughout, and it is quite difficult to say where one species ends and the next begins." "The history of the cave bear becomes a demonstration of evolution, not as a hypothesis or theory but as a simple fact of record."

Corn

Plants and crops are also subject to evolution and domestication. Take for example corn, modern corn is actually an evolutionary descendent of a plant called teosinte. Instead of nature and natural selection regulating which genes get passed down, man stepped in to decided what genes were favorable enough to be passed down. Between 6,000 and 10,000 years ago, Native Americans domesticated teosinte by only planting seeds from those with the most kernels and discarding the rest. Their goal was to improve the ear and its kernels. A teosinte ear is only 2 to 3 inches long with five to 12 kernels, compare that to modern domesticated corn's 12-inch ear that boasts 500 or more kernels!