Changes Time http://evolution.berkeley.edu/evosite/evo101/index.shtml

The theory of Evolution Evolution is known as the gradual change in the characteristics of a species over time.

The theory of Evolution Evolution is known as the gradual change in the characteristics of a species over time. A species is a group of organisms whose members look alike and successfully reproduce among themselves.

The Theory of Evolution Charles Darwin is considered to be the founder of modern evolutionary theory.

Other Terms to Know: Genetic Drift - Random fluctuations in the frequency of the appearance of a gene in a small isolated population, presumably owing to chance rather than natural selection.

Other Terms to Know: Gene Flow- Transfer of genes from one population to another of the same species, as by migration or the dispersal of seeds and pollen.

Other Terms to Know: Mutation - a change in a DNA sequence, usually occurring because of errors in replication or repair

Other Terms to Know: Recombination – AKA Crossing Over - a process in which pairs of chromosomes swap DNA with one another. This happens during gamete formation.

The Theory of Evolution On the Origin of Species established evolution by common descent as the dominant scientific explanation of diversification in nature.

Natural selection is a mechanism for changes in populations that occurs when organisms with favorable variations survive, reproduce, and pass on traits to the next generation. Artificial selection is the breeding of certain traits over others.

Evidence for Evolution Biogeography (“Bio” – Life; “Geo” – Earth) is the study of how species are distributed spatially across the landscape (geographically). The distribution pattern across the globe of many species does not make sense, unless they shared a common ancestor. Evolutionary theory predicts that modern species should be found close to where their ancestors were, regardless of the environmental conditions.

Evidence for Evolution Islands should contain plants and animals that are closely related to the species on the nearest mainland, even if the mainland and island have different environments. This indicates that early ancestors of species migrated and as the environments changed, the organisms adapted to their unique island environment over time.

Evolutionary theory of biogeographical distribution also fits in with the idea of continental drift. Similarites among species of plants and animals that are located on different continents could be a result of a common ancestor before the continents separated.

Evidence for Evolution Figure A shows the land bridges between continents in past geological time and Figure B shows the barriers formed when the land bridges were submerged under water.

Evidence for Evolution The fossil record for the camel indicated that evolution of camels started in North America, from which they migrated across the Bering Strait into Asia and hence to Africa, and through the Isthmus of Panama into South America. Once isolated, they evolved along their own lines, giving the modern camel in Asia and Africa and llama in South America.

Evidence for Evolution All living things contain similar DNA, RNA, and proteins. By comparing DNA sequences of two organisms, scientists can determine whether or not the organisms are closely related. The relationship can then be used to construct evolutionary pathways.

How many amino acid sequence differences between humans and: Horse? Tuna? Monkey?

A B C D E F G H

Evidence for Evolution Fossils also provide evidence for evolution. Fossils are the remains of once-living things that are preserved in Earth’s rocks.

Evidence for Evolution Fossils have found that many simpler life forms exist early in Earth’s history. The oldest fossils found are bacteria that lived 3.8 billion years ago.

Evidence for Evolution Other kinds of evidence that support organic evolution are adaptations. Anatomical Physiological Behavioral

about these structures? What do you notice about these structures?

Anatomical Homologous structures have different function but the SAME structures. These similarities indicates that the organisms probably had a common (the SAME) evolutionary origin.

about these structures? AND … what do you notice about these structures?

Anatomical Analogous structures have body parts that are similar in function but different in structure. These indicate that the organisms had different yet related ancestors.

Anatomical Some anatomical adaptations involve changes in the structure of body parts: mimicry and camouflage. Mimicry enables an organism to copy the appearance of another species.

MIMICRY

Milk Snake Coral Snake

Anatomical Some adaptations involve changes in the structure of body parts: mimicry and camouflage. Camouflage is a structural adaptation that enables an organism to blend in with its surroundings.

CAMOUFLAGE

Functionless Structures (Vestigial) ?? Some body structures, such as the human appendix and the eyes of cave fish, have reduced forms. These structures support the theory of evolution because they show structural changes over time.

Physiological Adaptations Some adaptations are physiological or changes in an organisms metabolic processes. Keep in mind that all things are made up of cells and the organelles are structurally and functionally similar in most organisms.

Physiological Adaptations Organisms are constantly changing to adapt to their environment. Take a look at organisms that have been exposed to antibiotic and pesticides. The organisms that survive have become selected because they are physiologically more resistant.

Imagine that there are 10 bacteria growing on your hand.

You use Germ-x to clean your hand everyday.

After 4 days, there are still 3 bacteria on your hands that have survived.

Is there anything special about these bacteria. Yes Is there anything special about these bacteria? Yes..they have something about their DNA that has made them different and strong enough to survive. So now what will happen?

Those 3 that are “resistant” will undergo Mitosis.

And after a week, your hands will be covered with tons of bacteria that are ALL resistant to Germ-X. 

Take a Look!! What do you notice about these organisms?

Embryology Early drawings done by scientists (like the one seen on the previous slide) were found to be “made up”. These drawings were used for many years to support the theory of evolution. Although these pictures have since been found to be fraudulent, there is still evidence today that states that at the embryological level, there are similarities…

Embryology The study of the development of embryos is the field of embryology. Studies of certain embryos indicate evolution from a common ancestor.