Introduction to Evolution Chapter 15

DO NOW !!! What is the connection between the words EVOLUTION AND REVOLUTION

What is Evolution ??? Evolution is “change over time” It is the process by which modern organisms have descended from ancient organisms

What is a Theory  A well supported testable explanation of a phenomena that have occurred in the natural world We are going to discuss and learn about the Theory of Evolution

Charles Darwin “Father of Evolution” Set sail on the H.M.S Beagle from England all around the world, especially the Galapagos Islands He made numerous observations during his travels

Darwin ’ s Observation ’ s DIVERSITY !!!!!! Living organisms and Fossils Amongst the Galapagos Islands Darwin noted that there were difference in climate, vegetation, and varieties in plant and animal types

Inferring in Groups Make inferences about what particular species of animals need to survive in the Galapagos Islands ** Remember it’s not only their PHYSICAL characteristics of any organisms that make it survive but also its behavior and relationship with its environment

Darwin Presents His Case

On the Origin of Species Darwin summarizes 6 main points #1 OVERPRODUCTION –most species produce far more offspring than are needed to maintain the population #2 COMPETITION – since living space and food are limited, offspring in each generation must compete. Only a small fraction survive long enough to reproduce

Main Points (continued) #3 VARIATION - The characteristics of the individuals in any species are NOT exactly alike. They may differ in the exact size or shape of a body, in strength, and in speed. These differences are called VARIATIONS. Others may affect the individual’s ability to get food, to escape enemies, or to find a mate.

#4 ADAPTATIONS –Because of variations, some individuals will be better adapted to survive and reproduce than others. In competition for existence, the individuals that have favorable adaptations to their environment will have a greater chance of living long enough to reproduce. An adaptation is any kind of inherited trait that improves an organism’s chance of survival and reproducing

#5 NATURAL SELECTION - “ Nature selects the survivors”. Individuals with variations that make them better adapted to their environment survive and reproduce in greater numbers than without such adaptations.

#6 SPECIATION –Over many generations, favorable adaptations gradually accumulated changes become so great that the net result is a new species.

Natural Variation VS Artificial Selection According to Darwin, natural selection is the differences among individuals in a species Naturally. In artificial selection, nature provided the variation among different organisms, and HUMANS selected those variations they found useful.

The Struggle for Existence Each member of a species must compete regularly to obtain food, living space, and other necessities for life. Those prey that are faster, better camouflaged, or better protected can avoid being caught.

Survival of the Fittest FITNESS – is the ability of an organism to survive and reproduce Individuals the are better adapted or MORE FIT are more apt to survive

Evolution of Populations Over time, it is a population that evolves not an individual organism

Descents with Modifications Each living species has descended, with changes, from other species over time According to the principle known as common descent, all species-both living and extinct were derived from a common ancestor

Evidence of Evolution Fossil records Geographic distribution of living species Homologous Body Structures- structures that have different mature forms but developed from the same embryonic development

Comparative Anatomy Homologous structures have similar structures and similar embryological development but have different forms and functions ( example human hand, whale flipper) Analogous structures have similar external forms and functions but different internal structures (example bird wing and insect wing)

Vestigial Structures Structures that are remnants of structures that were functional in an ancestral form In the human, wisdom teeth, the coccyx, and the appendix

Embryological Similarities Many embryos look very similar during the early stages of development