Theory of Evolution Chapter 15

Theory Science = Hypotheses that pass testing. Highest honor in science. Science = Hypotheses that pass testing. Highest honor in science. Common Usage = An idea, not necessarily supported with facts or tests. Common Usage = An idea, not necessarily supported with facts or tests.

How did living things achieve so much variety? Answer: Changes in DNA (mutations!)

Gradualism vs. Punctuated Equilibrium Gradualism- small mutations that occur frequently. Gradualism- small mutations that occur frequently. Punctuated Equilibrium- many mutations that occur all at once Punctuated Equilibrium- many mutations that occur all at once

Jean Baptiste Lemarck Use and disuse. Use and disuse. A giraffe’s neck is long after many generations of giraffe’s stretching their necks. A giraffe’s neck is long after many generations of giraffe’s stretching their necks. Can you see what is wrong with this???? Can you see what is wrong with this????

Endler Experimented with Guppies. Experimented with Guppies. Without predators… Without predators… increase in male guppies with large and brightly colored tails, because they are favored by females. increase in male guppies with large and brightly colored tails, because they are favored by females. With predators… With predators… decrease in male guppies with large and brightly colored tails, because the flashier fish are eaten by predators. decrease in male guppies with large and brightly colored tails, because the flashier fish are eaten by predators.

Charles Darwin Rode in HMS Beagle along coastal South America. Rode in HMS Beagle along coastal South America. Noticed variety in tropical life. Noticed variety in tropical life. Survival of the fittest. Survival of the fittest. All life is linked from a common ancestor. All life is linked from a common ancestor. Darwin never used the word ‘evolution.’ Did you know…

Darwin’s Voyage

Galapagos Islands

Galapagos Islands--A laboratory for evolutionary biology

DARWIN‘SFINCHESDARWIN‘SFINCHES

Darwin’s Theory of Natural Selection  There is variation within a population.  Some variations are good (helpful).  Not all young produced in a generation can survive!  This leads to a struggle for existence.  Survival of the fittest.  Those that survive and reproduce are those with the best variations for that specific environment.

Species Group of similar organisms. Group of similar organisms. Can interbreed successfully in nature. Can interbreed successfully in nature.  Offspring are healthy  Offspring are fertile (can reproduce)

These organisms are not new species…Why? Mule Mule Liger Answer… They are sterile! (Cannot produce children.)

Speciation Evolution of several species from 1 ancestor species. Evolution of several species from 1 ancestor species. Can be from isolation. Can be from isolation.  Geographic isolation  Reproductive isolation

Geographic Isolation Organisms are separated by a barrier. Organisms are separated by a barrier.  Islands that have broken apart.  Earthquake produces a large crack.

Reproductive Isolation Organisms that used to breed don’t any longer. Organisms that used to breed don’t any longer. Many Reasons… Many Reasons…  They now make sterile offspring.  They now mate in different seasons.

Mutations are successful if they help the organism survive and produce fertile offspring!

Evidence for Evolution Fossils Fossils DNA similarities DNA similarities Homologous Structures Homologous Structures Similar embryo development Similar embryo development

Fossil Evidence The age of fossils can be determined by radioactive decay OR by dating rocks around them. The age of fossils can be determined by radioactive decay OR by dating rocks around them. Fossils of simpler organisms are found in older rocks. Fossils of simpler organisms are found in older rocks. Fossils of more complex organisms are found in newer rocks. Fossils of more complex organisms are found in newer rocks. Fossil Evidence

How fossils are “made”… Fossil Evidence

Dating Fossils Fossil Evidence

1. Amount is constant (100% 14 C) while alive. 2. Organism dies C amount declines (due to radioactive decay) when organism dies. Fossil Evidence 14 Carbon Dating

DNA Similarities DNA Evidence The more similar the DNA, the more closely related organisms are. The more similar the DNA, the more closely related organisms are.  Your DNA is closer to your sister’s than your cousin’s.  Your DNA is closer to a pig than a duck.

Similarities in DNA show how closely related organisms are to each other. DNA Evidence

Comparing chromosomes of humans and chimpanzee Comparing chromosomes of humans and chimpanzee DNA Evidence

Chromosomes: Human Chimpanzee Gorilla Orangutan DNA Evidence

Hominoid Cladogram: Lengths and positions of arrow lines reflect the: Lengths and positions of arrow lines reflect the:  # of chromosome changes  relative timing  likely relationship ‘A’ refers to the Ancestral origin. ‘A’ refers to the Ancestral origin. DNA Evidence

Humans did NOT evolve from apes! We had a similar ancestor and BOTH of us evolved from that ancestor. We had a similar ancestor and BOTH of us evolved from that ancestor. It’s no wonder that we have many of the same DNA sequences! It’s no wonder that we have many of the same DNA sequences! DNA Evidence

Homologous Structures Similar bone structures. Similar bone structures. Homologous Evidence

Similar Embryo Development Embryos in all animals go through similar stages. Embryos in all animals go through similar stages. Humans even produce pharyngeal slits that are not seen later. Humans even produce pharyngeal slits that are not seen later. Embryo Evidence

Other Stuff…

Analogous Structures Similar function evolves separately! Similar function evolves separately!

2 Versions of the Hominoid Family Tree

Lucy Discovered in Discovered in million year old bones. 3.2 million year old bones. Almost half of her bones were found! Almost half of her bones were found! Ethiopia (in Africa) Ethiopia (in Africa) 3 feet, 8 inches tall!

Evolution Observed: Peppered Moths Light moths Dark moths Less pollutionMore pollution

Opposition to the Theory of Evolution Evolutionary theory, more than any other scientific theory, is regularly challenged. Evolutionary theory, more than any other scientific theory, is regularly challenged. Much of the objection comes from a mistaken view of what a scientific theory represents. Much of the objection comes from a mistaken view of what a scientific theory represents.

– –Some of the evidence for evolution is historical in nature, and cannot be demonstrated experimentally. – –Consistency in the evidence derived from many sources, using many methods, from within biology (e.g., embryology, biochemistry) and from other disciplines (geology, nuclear chemistry), for more than a hundred years has convinced most scientists that the core principles of evolution accurately describe the story of life on Earth.

The End

Observation #5 Much of this variation is heritable. Much of this variation is heritable.  Survival is not random, but depends in part on the hereditary constitution of the surviving individuals. Those individuals whose inherited characteristics fit them best to their environment are likely to leave more offspring than less fit individuals.  This unequal ability to survive and reproduce will lead to a gradual change in a population