EVOLUTION Key Points Heritable characteristics increase or decrease

EVOLUTION

Key Points Heritable characteristics increase or decrease an organisms chance of survival Evolution is the change of the genetic makeup of a population over time More closely related organisms have more closely related DNA and proteins Many organisms have similar structures, and many organisms develop similarly

Key Points Mutations that lead to evolution occur randomly All species on earth are related by a common ancestor The fossil record shows organisms that are no longer alive Environmental pressures, genetic drift, mutation and competition for resources lead to evolution

How did life on earth begin? There are many theories Information about early earth comes from rocks The earth is ~4. 6 billion years old The oldest clues about life on earth are ~3. 5 billion years old

Fossils Fossils are preserved evidence of organisms 99. 9% of all organisms are extinct Very few organisms become fossilized Many fossils are casts � Minerals fill in the

Dating Methods Relative Dating A technique where items (rocks or fossils) are dated by comparing the soil layers The Law of Superposition Sedimentary rock is deposited in layers � Older layers are deeper � Newer layers are on top � Explain the picture?

Dating Methods Radiometric Dating Uses radioactive isotopes to date rocks or organic material � Uses the half life of the isotope Carbon-14 Decays to Nitrogen-14 � Half life is 5730 years � Can date organisms up to 50, 000 years � Potassium-40 Used to date older items � Can only be used to date �

Geologic Time Represents major geologic events

Spontaneous Generation. A Hypothesis � Spontaneous Francisco generation- life arises from no life Redi’s experiment opposes the hypothesis

Biogenesis- a theory Biogenesis- life arises from life Louis Pasteur – biogenesis is true for microorganisms

Origins of Life Simple organic molecule formation Organic molecules could be synthesized by simple reactions UV light from the Sun and lightning may have been the primary energy source Shark Bay, Australia

Miller and Urey Simple organic molecules are made from inorganic molecules Conditions were like that of early earth

Cell Evolution Prokaryotes evolved first � Archea most closely resemble earth’s first life � They are autotrophs, energy does not come from the sun, they do not need oxygen Photosynthesizing prokaryotes evolved next � Oxygen was just a byproduct Eukaryotes evolved by prokaryotes developing symbiotic relationships

Endosymbiont Theory

STOP You are a Paleontologist Activity

Brontosaurus Old New

Natural Selection

Darwin & Natural Selection Darwin was a naturalist on the HMS Beagle � He was also a companion to the captain � He collected biological samples Darwin collected many birds, mockingbirds and finches on the Galapagos Islands � Each island had similar birds, but they were slightly different

Example of Adaptive Radiation

Beaks – specific for diet

Artificial Selection and Natural Selection Humans could changes species (such as dogs) by artificial selection Darwin’s Hypothesis � New species could appear gradually through small changes in ancestral species � Support:

Natural Selection Individuals in a population show variation Variations are inherited Organisms have more offspring than can survive on the available resources Variations that increase reproductive success will have a greater chance of being passed on

Convergent evolution Divergent evolution

Support for Evolution Fossils � Fossils show species that lived long ago � Ancient species share similarities with living species Glyptodont Armadillo

Support for Evolution Derived traits: newly evolved features that do not appear in common ancestors � Feathers Ancestral traits � More primitive features that do appear in ancestral forms

Homologous Structures Anatomically similar structures inherited from a common ancestor � Structures are used for different purposes

Vestigial Structures that are reduced in form � They are useful in related organisms Features of ancestors that are no longer useful will become smaller or lost over time

Analogous Structures used for the same purpose but are not from a common ancestor

Comparative Embryology Vertebrate embryos look very similar as embryos Develop differently as they get older

More Comparative Embryology

Comparative Biochemistry Common ancestry can be seen in metabolic molecules � DNA � Amino acid sequences More closely related organisms have similar sequences

How Organisms Evolve

“Blue Skinned People” The Fugate Family Affects an entire family from isolated Appalachia (Kentucky) Skin tinged blue almost “purple” Recessive diseases Methemoglobinemia � � Family had a deficiency in the enzyme called cytochrome-b 5 methemoglobin reductase � Blood disorder in which an abnormal amount of methemoglobin -- a form of hemoglobin Hemoglobin - responsible for distributing oxygen to the body “blue” hemoglobin never converted to “red” hemoglobin No side health effects � Many Futates lived into their 80 s and 90 s. Martin Fugate came to Troublesome Creek from France in 1820 and family folklore says he was blue. His wife carried the recessive gene. Of their seven children, four were reported to be blue

Genetic Drift Change in allele frequency � Caused by chance � Seen in small populations

Founder Effect A small sample of a population emigrate to a new area Alleles that were uncommon in the parent population become popular Population Bottleneck The population almost goes extinct A few surviving members survive and reproduce

Gene Flow Immigration and emigration Increases variation within a population Nonrandom Mating Promotes inbreeding Can cause alleles frequency to change Female is usually choosey Male usually displays traits

Types of Selection The best suited individuals survive Derive a situation that could cause each graph.

Human Evolution

Human Evolution What is a primate (Ape) � Manual dexterity � Flexible bodies � Limber shoulders and hips � Large Brain � Can solve problems � Social � Newborns dependent on mother � Have fewer offspring Are you an ape?

Humans Bipedalism- changing environment Large Brain- evolved after bipedalism

Primate/human Tree

So, are we an ape?