A fossil is: Any evidence of an organism that lived long ago Sedimentary Rock Almost all fossils are found in How do scientists determine the age of fossils? Relative Dating Absolute Dating The deeper the fossil the older it is Does not give exact ages The Earth is always shifting, so fossils may not be in the original position AKA Radioactive dating Can give an actual age to a fossil Measures the amount of certain radioactive isotopes that are found in the fossil
Charles Darwin Darwin voyaged around the word in the HMS Beagle from 1841-1846 He collected many natural samples and made many observations from his trip around the world that lead to his ideas about natural selection Artificial Selection - Only allowing organisms with desirable traits to breed so they can pass on those traits Evolution by Natural Selection Fitness the ability to survive & reproduce Survival of the fittest In nature living things create more offspring than the environment can support. In any population there will be genetic differences (variations) Evidence for Evolution More individuals with useful variations will survive & pass those traits to the next generation
Bacterial resistance Some bacteria are naturally resistant to antibiotics. They survive and pass this immunity to the next generation Darwin s observations Embryology Nearly all animals have similar structures as they are developing (Embryo early stage of life) Fossils Shows similarities and differences between some ancient creatures and modern living things Biochemistry All living things use DNA & RNA to make proteins & ATP to release energy EVOLUTION Anatomy Homologous Structures Have similar parts but different functions (bird wing-human arm) Analogous Structures Have similar function but different structure (bird wing-insect wing) Vestigial Structures Many living things have similar internal structures A useless structure (ear muscles, appendix, tailbone, body hair)
Population: A group of organisms of one species that live in the same place at the same time Populations evolve not individuals!! Remember, an allele is different forms of a gene Gene Pool All of the genes in a population Allelic v frequency The percentage of a specific allele Hh Hh Hh HH hh Hh HH H = 10/18 =.56 = 56% h = 8/18 =.44 = 44% hh HH When the allelic frequency of a population stays the same over many generations it is called A change in environment will usually disrupt the genetic equilibrium in one of three ways Original Environment Genetic 1) Stabilizing Selection equilibrium Natural selection favors the average individual
2) Directional Selection Natural selection favors one of the extremes 3) Disruptive Selection Natural selection favors both extremes may create 2 different species Speciation - The evolution of a new species For speciation to occur there has to be no mating between the two populations This happens because of Geographic Isolation or Reproductive Isolation When physical barriers separates a population When two populations no longer mate and produce fertile offspring
SPECIATION (cont.) Original population Geographic Isolation Reproductive Isolation Speciation can occur slowly, little by little or in rapid bursts with little change between bursts Gradualism Punctuated equilibrium Divergent Evolution (Adaptive radiation) Many species are formed from one original species Two Types of Evolution Convergent Evolution Organisms that are not closely related evolve similar traits
Classification of living things Kingdom Animalia (Animals) Phylum Chordata (Spinal Cord) Class Mammalia (produce milk for offspring) Order Primate (Opposable thumb/large brain) Family Hominidae (Great Apes) Genus Homo (Upright walkers) Species Sapiens (capable of logical thought, language & introspection)
Eubacteria Archaebacteria Protists Prokaryotes Unicellular Autotrophs or Heterotrophs Most bacteria on Earth Prokaryotes Unicellular Autotrophs or Heterotrophs Live in extreme areas such as thermal vents deep in the ocean Fungi Plants Animals Eukaryotes Unicellular or Multicellular Heterotrophs (Decomposers) Absorb nutrients from organic material in the environment Eukaryotes Multicellular Autotrophs Have cells organized into different tissues Most cannot move from place Eukaryotes Unicellular or Multicellular Autotrophs or Heterotrophs Most live in aquatic environments Eukaryotes Multicellular Heterotrophs Have tissues organized into organs and organ systems Most are mobile
Kingdom: Animalia (animal) Phylum: Chordata (spinal chord) Class: Mammalia (mammals) Order: Primates (opposable thumb, binocular vision, large brains) Family: Hominidae (great apes) Genus: Homo (upright walkers) Species: sapiens (brain capable of abstract reasoning, language and introspection)