Evolution Natural Selection

Review Spontaneous Generation Vital Force Living things come from nonliving things Vital Force The air contains something that produces microorganisms

Review When was the Earth formed? What were the first life forms? 4.6 billion years ago What were the first life forms? Prokaryotic cells Define Evolution. Describes how things change over time

Thoughts in 18th Century Scientists believed species were permanent and unchanging Earth was only thousands of years old Scientists began to present evidence that species change over time and that the Earth is much older.

Scientists are influenced by other scientists James Hutton: a geologist in 1785 Realized that certain kinds of rocks are formed from molten lava Some other rocks form very slowly, as sediments build up and are squeezed into layers Froces beneath Earth’s surface push rock layers upward and build mountain ranges Mountains can be warn down by rain, wind, heat and cold

Scientists are influenced by other scientists Charles Lyell-1830-1833 Laws of nature are constant over time and that scientists must explain past events in term of processes they can observe in the present

Hutton and Lyell Laws of nature concluded that Earth is extremely old and that the processes that changed Earth in the past are the same processes that operate in the present

Jean-Baptiste Lamarck French Naturalist Suggested that organisms could change during their lifetimes by selectively using or not using various parts Suggested that individuals could pass these acquired traits on to their offspring, causing change over time

Jean Baptiste Lamarck 1809 Inheritance of Acquired Characteristics Individuals acquired traits during lifetime as a result of experience then can pass those traits onto their offspring. Larger muscles from work, children would have larger muscles

Thomas Malthus English Economist 1798- notes humans were being born faster that dying causing over crowding Forces working against population growth, include war, famine, and disease Applied to other organisms as well

Alfred Russel Wallace English naturalist working in Malaysia 1850’s Thoughts were almost identical to Darwin’s which caused Darwin to publish book

Charles Darwin 1809-1882 Traveled on the Beagle Noticed similar organisms around the world Did a lot of work on Galapagos Islands off of South America Wrote book On the Origin of Species by Means of Natural Selection Used the phrase Descent with modification Beaks of finches on Galapagos Islands

Natural Selection Four main parts of Darwin’s reasoning Overproduction: more offspring can be produced than can survive to maturity Genetic Variation: individuals within a population have different traits Struggle to Survive: individuals must compete with each other for limited resources Differential Reproduction: individuals that have certain traits are more likely to survive and reproduce

Speciation Speciation: the formation of new species Convergent Evolution: different species evolve similar traits because of environment they live in These species are not related Divergent Evolution: organisms begin to look different because of the environment they live in Adaptive Radiation: a new species in a new environment will undergo divergent evolution until population fills many part of the environment

Speciation Geographic Isolation: a population is split due to the habitat becoming divided Ex: canyons, mountain ranges, bodies of water, deserts, accidentally transported to new area Reproductive Isolation: there are barriers to successful breeding between population groups in same area Prezygotic: before fertilization Ex. Mating calls, time of mating Postzygotic: after fertilization Ex: offspring cannot reproduce

Rates of Speciation Gradualism: changes occur at a regular, gradual rate Punctuated Equilibrium: Many years of no change, then all of the sudden have a significant change

Evidence of Evolution Fossil: remains or traces of an organism from long ago. Biogeography: study of the location of organisms Animals that seemed closely related yet are adapted to different environments in nearby regions. Animals that seemed unrelated but have similar adaptations to similar environments

Evidence of Evolution Anatomy and Embryology Anatomy: the study of body structure Embryology: the study of how organisms develop Homologous Structures: anatomical structures that occur in different species and that originates by common ancestor Ex: human, penguin, alligator, bat all have a humerus, radius, and ulna

Evidence of Evolution Biological Molecule Analogous Structure: structures that have similar functions but different structures Ex: wings of birds and insects Vestigial Structure: structure that have no known function Ex: tailbone, appendix Biological Molecule DNA and RNA The greater number of similarities between any given species the more closely related