Darwin’s Theory of Evolution by Natural Selection Ms. Eramchuk

Darwin’s Theory  Evolution happens to POPULATIONS, NOT INDIVIDUALS

Let’s Talk About Finches!  Lab Questions:  How do the different tools represent different adaptations?  If the environment changed such that the seed type was more abundant, what do you think would happen to the population of that bird?  Does having a different shaped beak or different tool help reduce competition between the birds searching for food? Explain why or why not.

These Hawaiian Honeycreepers all evolved from a single ancestor, which arrived on the islands long ago. With no other birds for competition, the honeycreepers began to feed on different foods. Over many generations, their bills changed to cope with their new diets.

The Concepts of Darwinism  Darwin’s view of life was of ‘descent with modification’: descendants of ancestral forms adapted to different environments over a long period of time  The mechanism for adaptation is called ‘natural selection’, and is based on a number of principles:

Overproduction

 Species produce more offspring than are needed; only a fraction of the offspring survive to reproduce

Competition

Competition:  Offspring in each generation must compete for limited resources; only the strongest will survive and reproduce

Variation

 Characteristics vary in each species and will affect their ability to obtain food, escape predators, or reproduce

Variation A fish with a curved tail is able to swim faster and escape predators. With each generation, more fish with a curved tail will survive to reproduce.

Adaptations

 Individuals which possess favourable adaptations to their environment have a greater change of living longer and reproducing

Natural Selection

 The environment selects plants and animals with optimal traits to be the parents of the next generation

Speciation

 Over many generations, favourable adaptations accumulate in a species and the unfavourable ones disappear

POST ON EDMODO:  Post an example what the term “fittest” means in the phrase “survival of the fittest”  Include a photo and and 1-2 ways that your species has evolved to be well-suited to its environment.  E.g. stick insects blending in with branches