Evolution
•Evolution is descent with modification; the
idea that living species are descendents of
ancestral species that were different from
present-day ones
•Evolution describes the genetic changes in a
population over time
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Lecture Notes on Evolution - Principles of Biology | BIO 101, Study notes of Biology
Material Type: Notes; Professor: McNamara; Class: Principles of Biology; Subject: Biology; University: Suffolk County Community College; Term: Fall 2009;
Typology: Study notes
Pre 2010
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Evolution
- (^) Evolution is descent with modification; the idea that living species are descendents of ancestral species that were different from present-day ones
- (^) Evolution describes the genetic changes in a population over time
Evolution
- (^) Organisms are adapted to their environment; a good fit
- (^) As descendents of a remote ancestor spread into various habitats over millions and millions of years, they accumulate diverse modifications (adaptations) that fit them to specific ways of life
- (^) = descent with modification (evolution)
Natural Selection
- (^) Natural selection is the process by which favorable, inherited traits become more numerous in successive generations of a population of reproducing organisms
- (^) Over time, natural selection leads to species that are well adapted (highly evolved) to their environments
Natural Selection
- (^) Natural selection is the brain child of Charles Darwin; a naturalist who sailed around the world and noted the unique adaptations of animals in many diverse environments (most notably the Galapagos Islands)
The Principles of Natural Selection
- (^) Variation
- (^) Some individuals, due to heredity or mutation, possess characteristics which make them better adapted to their environment
The Principles of Natural Selection
- (^) Inheritance of Traits
- (^) Best-suited organisms will survive to produce more individuals that share same adaptation
1 Population with varied inherited traits 2 Elimination of individuals with certain traits 3 Reproduction of survivors Certain individuals with a distinct, inherited characteristic will be selected against, while others with a (different) distinct, inherited trait will survive
Let’s look at an example…
Normal allele; vulnerable to pesticides Alternate allele; resistant to pesticides Survivors ‘Resistant’ allele passed to next generation
Evolution
- (^) Remember, evolution is the genetic change in populations over time
- (^) Individuals do NOT evolve; evolution refers to generation-to-generation changes
- (^) Evolution does not lead to perfectly-adapted organisms; natural selection results from environmental factors that vary from place to place and from time to time (a trait that is favorable in one situation may be detrimental in another)
Evolution
- (^) Evolution is a gradual change over time
Evidence for Evolution
Trilobite: 230 mya Seed fern: 150 mya Allosaurus : 65 mya
Evidence for Evolution
- (^) Microevolution – evolution can be observed in nature (pesticide-resistance in insects, Peppered moths/industrial melanism)
- (^) A well-known example of microevolution is the case of the Peppered moths in England during the Industrial Revolution
- (^) Known as “industrial melanism”
Microevolution
- (^) Poor air quality killed the lichens which covered the otherwise dark trees and camouflaged the light moths against predation
- (^) Light moths were predated on; dark moths were not
- (^) (Prior to the industrial revolution, the reverse would be true)
Evidence for Evolution
- (^) Artificial selection – the process by which humans have modified other species by selectively breeding for desired traits
- (^) Darwin got the idea of natural selection from artificial selection! www.flickr.com/photos/terryan www.flickr.com/photos/rinalia/ dchristine/2399227035/ 3285371111/