Principles, Populations, The history of life Evolution Principles, Populations, The history of life

Concept 10.1 Concept of Evolution Process of biological change by which descendants come to differ from their ancestors Search for reasons for Earth’s great biological diversity

Naturalist An expert in or student of natural history In Evolution 10.1 Naturalist An expert in or student of natural history In Evolution Carolus Linnaeus Georges Buffon Erasmus Darwin Jean-Baptiste Lamarck These men laid the foundations in the early ideas of evolution

Scientists and their Contributions 10.1 Scientists and their Contributions Carolus Linnaeus- proposed a new system of organizations for plants animals, minerals, based upon their similarities Georges Buffon- discussed important ideas about relationships among organisms, sources of biological variation, and the possibility of evolution Erasmus Darwin- considered how organisms could evolve through mechanisms such as competition Jean-Baptiste Lamarck- presented evolution as occurring due to environmental changes over long periods of time

Theories of Geological Change 10.1 Catastrophism Different fossils could be found in different rock layers States that natural disasters have occurred shaping landforms and causing species to go extinct Gradualism States that changes in landforms resulted from slow changes over time Gradual change of a species through evolutions Still referenced today Uniformitarianism States that the geologic processes were uniform through time Changes occur at a constant rate and are ongoing Favored theory of geologic change

Darwin’s Observations 10.2 Darwin’s Observations Variation Difference in the physical traits among individuals Interspecific-among species groups Intraspecific-one species Adaptation Feature that allows the organism to better survive in its environment Ability to adapt to the surroundings can lead to genetic change Based on his observations, he believed that geologic processes add up over time in a uniform manner (uniformitarianism)

Darwin’s Evidence

Selection Artificial Selection (breeding) Heritability 10.3 Selection Artificial Selection (breeding) Humans make use of the genetic variation in plants and animals and choose the favorable genes Heritability The ability of a trait to be passed down through generations Natural Selection Nature chooses the traits to pass on Traits are only selected if they give the organism advantages Affects phenotypes (physical traits)

10.3 Natural Selection Four main principles in the theory of Natural Selection Variation -Heritable differences in populations Overproduction -An increase in offspring, increases competition for resources Adaptation -Beneficial traits allow some organisms to thrive Descent with modification -The beneficial traits will be passed on over time, producing a species that is suited for survival and reproduction

Evidence of Evolution 10.4 Fossils Geography Embryology Anatomy Fossil record set a time frame Geography Study of distribution of similar populations Embryology Similarities between larvae of different species Anatomy Homologous structures -similar in structure, different functions Analogous structures -similar in function, different structure Vestigial structures -remnants of structures found in ancestors

Evolution of Populations

11.1 Genetic Variation Genetic variation increases the chances for members of a population to survive The greater the variation in phenotypes, the greater chances of survival in a changing environment Variation is stored in a gene pool, which factors in allele frequency

Distributions of Traits 11.2 Distributions of Traits Normal Distribution -The frequency is highest near the middle value and decreases towards the extremities -Phenotypes near the middle are most common creating a bell shaped curve

Selection changes distributions 11.2 Selection changes distributions Microevolution- observable change in allele frequency Can change the distribution in 3 ways Directional Selection Occurs when extreme phenotypes are favored Ex: drug resistant bacteria Stabilizing Selection The intermediate phenotype is favored Ex: Gall size in goldenrods Disruptive Selection The extreme phenotypes are favored Ex: feather color in birds

Directional Stabilizing Directional Name that distribution

Genetic Drift 11.3 Movement of alleles between populations leads to gene flow This change in frequency occurs in two ways: Bottleneck Effect Genetic drift occurs after the population has been greatly reduced Founder Effect Genetic drift occurs after a small number of the population leave and colonize a new area

Genetic Drift

Hardy-Weinberg Equilibrium 11.4 Hardy-Weinberg Equilibrium Found a way to predict population frequencies using five conditions If these conditions are met, then the population is not evolving Very large population No emigration or immigration No mutations Random mating No natural selection

Hardy-Weinberg Equation 11.4 Hardy-Weinberg Equation While populations rarely meet the criteria, this formula can be used to compare data p2 + 2pq + q2 = 1 p = the frequency of the dominant allele (TT) q = the frequency of the recessive allele (tt)

Five factors of evolution 11.4 Five factors of evolution The Hardy-Weinberg equilibrium is not common in nature In nature, populations evolve in response to environmental factors such as: Genetic drift Gene flow Mutation Sexual selection Natural selection

Evolution, Isolation, Speciation 11.5 If gene flow stops then isolation occurs Isolation leads to speciation, which is a rise of two or more species from one existing species Examples include: Behavioral Isolation -mating behaviors Reproductive Isolation -populations can no longer mate with each other Geographic Isolation -physical barriers divide a population Temporal Isolation - timing prevents reproduction

11.6 Patterns in Evolution The effects of natural selection add up over many generations Mating throughout generations is NOT random The evolutionary paths of two or more species can become connected through the process of coevolution Extinction and speciation events also appear in patterns in the fossil record

The History of Life

The Fossil Record 12.1 Fossils are more diverse than the giant dinosaur skeletons seen in museums Fossils can be produced in several ways Permineralization Natural casts Trace fossils Amber preserved fossils Preserved remains

Aging Fossils 12.1 Relative vs Radiometric dating Relative- estimates the time during which an organism lived by comparing rock samples Radiometric- uses natural decay of isotopes Isotopes are atoms that have the same number of protons but different number of neutrons An isotopes half-life is not effected by environmental conditions such as temperature of pressure

Radiocarbon dating

Geologic Time Scale Index fossils are another tool to determine the age of rock layers These fossils give information of a specific time span over large geographic areas The time scale represents Earth’s major changes and consists of three major units Eras Periods Epochs

Geologic Scale 12.2 Paleozoic Mesozoic Cenozoic Ancient life 542-299 mya Mesozoic Middle life 251-145 mya Cenozoic Recent life 65 mya-present

12.5 Paleozoic Members of every major animal group evolved within only a few years More than 90% of marine life and 70% of land species went extinct Multicellular animals radiated The first vertebrates evolved Also known as the Cambrian explosion!

Mesozoic 12.5 Known as the age of reptiles Oldest direct ancestor of mammals first appeared Three periods: Triassic Jurassic Cretaceous - ended with a bang!!!

Cenozoic Includes present time Two periods: Tertiary- Quaternary- placental animals and monotremes Homo sapiens evolved (100,000 ya) Quaternary- Included ice ages, the last of which occurred 10,000 years ago

Primate Evolution 12.6 During the Cretaceous period primates evolved Characteristics included: Flexible hands and feet Forward looking eyes Enlarged brains Opposable thumbs

12.6 Family Differences Culture and tools are key components in human evolution Utilization of tools lead to levels of cultural adaptations and sophistication of humans Human evolution would not have advanced as it did without an enlarging skull and brain size