Evolution and Darwin

Evolution Change over time The processes that have transformed life on earth from it’s earliest forms to the vast diversity that characterizes it today. Theory-a well-supported testable explanation of events that have occurred in the natural world.

Old Theories of Evolution Jean Baptiste Lamarck (early 1800’s) proposed: “The inheritance of acquired characteristics” He proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime, which it passes on to its offspring.

“The Inheritance of Acquired Characteristics” Example: A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

Charles Darwin http://Early Life of Charles Darwin Darwin set sail on the H.M.S. Beagle (1831-1836) to survey the South America to collect plants and animals. On the Galapagos Islands, Darwin observed species that lived no where else in the world. These observations led Darwin to write a book.

Galapagos Islands

Charles Darwin Influences James Hutton Proposed that Earth is shaped by geological forces that took place over long periods of time. Thomas Malthus Proposed that famine, war and poverty limited human population

Charles Darwin Influences Charles Lyell led Darwin to realize that natural forces gradually change Earth’s surface and that the forces of the past are still operating in modern times.

Charles Darwin Wrote in 1859:“On the Origin of Species by Means of Natural Selection” Artificial selection-humans selected the genetic variation that they found useful Proposed a mechanism for evolution: NATURAL SELECTION- nature selected the genetic variation that they found useful

Artificial Selection The selective breeding of domesticated plants and animals by man. Question: What’s the ancestor of the domesticated dog? Answer: WOLF

Natural Selection Individuals with favorable traits are more likely to leave more offspring better suited for their environment. Can’t be seen but results shown Example: English peppered moth (Biston betularia) - light and dark phases

Evolution by Natural Selection Struggle for Existence Members of species regularly compete for food, living space, and other necessities. Survival of the Fittest Fitness: ability of an individual to to survive and reproduce in its environment Adaptation: inherited characteristic that increase an organism chance of survival SURVIVAL OF THE FITTEST-Survive and reproduce the most successfully

Struggle for Existence

Evolution by Natural Selection Descent with Modification All living organisms are related to one another Common Descent Single “Tree of Life” All species were derived from common ancestors

Intermission

Fossil Records

Evidence of Evolution Fossil Record: Fossils and the order in which they appear in layers of sedimentary rock (strongest evidence). Ancestral traits-primitive features that do appear in ancestral form Derived traits-newly evolved features that didn’t appear in ancestors

Evidence of Evolution Biogeography: Geographical distribution of species.

Evidence of Evolution Comparative Anatomy Homologous Structures -Structures that has different mature form but develop from same embryonic tissue. Vestigial structure -Structure that is no longer functioning Analogous structures -Structures that has same mature form but develop from different embryonic tissue.

Evidence of Evolution 4. Comparative embryology Study of structures that appear during embryonic development. 5. Molecular biology: DNA and proteins (amino acids)

Adaptation Adaptation: a trait shaped by natural selection that increases an organism's reproductive success Fitness: a measure of the relative contribution success of the following generation Types of adaptation Camouflage Mimicry Antimicrobial resistance

Summary of Darwin Theory Individual organisms differ and some of the variation is heritable. Organisms produce more offspring than can survive and many that survive don’t reproduce They will compete for limited resources Each unique organisms has different advantages and disadvantages in the struggle of existence. Individuals best suited to their environment and reproduce most successfully. Species alive today are descended with modification from ancestral species that lived in the distant pastSingle tree of life.

Video Darwin: Dangerous Idea