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Transcript
Evolution Natural Selection Genetic Basis of Evolution Speciation The History of the Earth Biological Evolution • Scientists look at the history of living things. Fossils – the remains or impressions of an organisms that lived in the past • Evolution is the changes in a population over time. Population – a group of organisms of the same species that live in the same area • Biological evolution – the change in the gene pool of a population over time • Gene pool – the genes found within a population Charles Darwin • Darwin sailed around the world, making observations on nature. • Patterns of Diversity – organisms well suited to their environment • Common descent – a theory that present organisms descended from past organisms • Descent with modification – the theory that more recent species of organisms are changed descendants of earlier species Ideas that shaped Darwin’s thinking • Belief that many periods of creation in which catastrophic events killed species. • Lyell and Hutton – dynamic earth process have shaped the Earth over many periods of years. The Earth does not look the same as it did when it was first created. Ideas that shaped Darwin’s thinking • Lamarck proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could be passed on to their offspring. This lead to a change in species. Ideas that shaped Darwin’s thinking • Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone Darwin’s Theory of Evolution • Evolution – the process by which modern organisms have descended from ancient organisms (change over time). • Heritable variation in organism is caused by variations in the genes. • Adapts – to change genetically over generations to become more suited to the environment • Modern synthesis – a theory that states evolution involves changes in a population’s gene pool over time Darwin’s Theory of Evolution • Artificial selection – nature provided the variation and humans selected those variations that they found useful Darwin’s Theory of Evolution • Struggle for existence – high birth rates and shortage of life’s basic needs forces organisms into a competition for resources • Survival of the fittest – ability of an individual organism to survive and reproduce successfully in it’s environment • Adaptation – any inherited characteristic that increases an organism’s chance of survival Darwin’s Theory of Evolution • Natural selection – only certain individuals of a population produce new individuals, based on the traits and their suitability to the environment. Man does not intervene in natural selection Darwin’s Theory of Evolution • Organisms tend to produce more offspring than can survive. Overproduction – when organisms produce more offspring than can survive • Individuals in a population vary in many traits. • Individuals with alleles best suited to the environment are more likely to survive. • Individuals that survive produce more offspring. Differential reproduction – individuals leave more offspring that other individuals. Evidence of Evolution • Fossil record – Earth must be very old. • Fossils from older rocks show less diversity that fossils from younger rocks • Fossils could show organisms change from one form to another, however, they don’t exist Evidence of Evolution • Geologic time – all the time that has passed since the Earth formed • Paleontologist – a scientist who studies fossils • Radioactive elements – an element that decays to form another element • Since decay happens over a consistent time, scientists can estimate how old a rock is based on the rate of decay. Evidence of Evolution • Geologic time scale – a table that divides the Earth’s history into time periods • Precambrian period (4 billion years – 550 million years ago) – mostly bacteria and small cellular organisms • Paleozoic period (550 million years – 250 million years ago) – first fishes and land plants, amphibians, and small reptiles – Invertebrates: an animal that does not have a backbone – Vertebrates: an animal that has a backbone Evidence of Evolution • Mesozoic period (250 million years to 65 million years ago) – dinosaurs, first flowering plants and birds, mammals – Reptile – an egg-laying vertebrate that breathes with lungs • Cenozoic period (65 million years ago to present) – mammal evolution and humans Evidence of Evolution • Plate tectonics – a theory that the Earth’s surface is made of large sections of crust that move • Continental drift – a theory that the major landmasses of the Earth move • Magma – hot, liquid rock inside the Earth • Plate – a large section of the Earth’s crust that moves • Crust – the outer layer of the Earth Evidence of Evolution • Geographic distribution of living things • Members of the same species look very different because of the environment Members of different species have similar behaviors and physical traits because of the environment Evidence of Evolution • Homologous structures – different species have similar structures to perform similar functions • Vestigial organs – organs that have little or no use on certain species Evidence of Evolution • Embryology – different species have similar early life stages Genetic Variation • Gene pool – consists of all the genes, including the different alleles, present in a population • Relative frequency - number of times that an allele occurs in a gene pool • Evolution, in genetic terms is any change in the relative frequency of alleles in a population • Two main sources of genetic variation: mutations and genetic shuffling Genetic Change • Single-gene trait – a characteristic controlled by a single gene • Polygenic trait – a characteristic controlled by many genes • Natural selection on single gene traits can lead to changes in allele frequencies and then to evolution • Recombination – the creation of new combinations of alleles of an offspring Genetic Change • Gene flow – the movement of genes into or out of a population • Genetic drift – the random changes in the gene pool of a small population • Endangered – a condition in which there are almost no organisms of a certain species • Extinction – the death of all members of a species • Habitat – place where an organism lives Genetic Change • Hardy-Weinberg Equilibrium – a principle that states the frequencies of alleles in a population do not change unless evolutionary factors act on the population • In order for the principle to work, changes must occur within a population • p2 + 2pq + q2 = 1 Evolutionary Principles • Microevolution – the minor changes in a population’s allele frequencies from generation to generation – Moths changes from light-colored to darkcolored • Macroevolution – the large-scale changes in a population over long periods of time – Extinctions or may result in a new species • Frequency – the rate of occurrence Speciation • Species – a group of living things that can breed with each other and produce offspring that are fertile, capable of producing offspring • Reproductively isolated – a division between populations that once mated, but can no longer mate and produce fertile offspring • Interbreed – to breed together Speciation • Biological species concept – principle that defines a species as populations that can interbreed and produce offspring – Donkeys and horses mate, but produce mules which are infertile. – Fireflies look similar, but different species do not mate Speciation • Ecological species concept – principle that defines species as populations that can interbreed and produce offspring based on their niche, the way of life of a species – Asexual reproduction – reproduction that involves one parent and no egg or sperm – Organisms that use asexual reproduction can still be defined as a species even though the do not have a mate Speciation • Allopatric speciation – when similar organisms do not interbreed due to physical barriers • Physical barriers could include mountains, forests, deserts, rivers, or oceans • Sympatric speciation – when similar organisms live nearby, but do not interbreed due to differences in behavior • Plant species that are grown for food, different animal mating rituals Speciation • Species become different because of different environments. Occur at different rates. • Stasis – showing little change over time • Punctuated equilibrium – a theory that states species stay the same for a long time, then new species evolve suddenly due to global changes and mass extinctions. • Coordinated stasis – pattern where most species appear at about the same time Speciation • Mass extinctions – the dying out of large numbers of species in a short period of time – One mass extinction 250 million years ago, Dinosaurs died in a mass extinction 65 million years ago – Volcanic eruptions, plate tectonics, asteroids hitting the Earth • Community – a group of different populations that live in the same area Speciation • Co-adaptation – one species becoming dependent on another species – Species come into contact with another species so much that they change with each other • Instantaneous speciation – a new species formed in one to several generations – Fruit flies breed on one plant, while another breed on another plant; genes mutate or combine in a short time Theory of Intelligent Design Age of the Universe/Solar System DNA/Microbiology Evolutionary Myths Intelligent Design • The watch and the watchmaker • Universe and life not made from a series of random processes. • Since non-living and living things show a great deal of complexity, there must be an intelligent designer that created it. Age of the Universe • Approximate age of the universe is between 17 billion and 22 billion years old • Hubble space telescope – furthest electromagnetic radiation detected • What is beyond the universe? • If the universe has an end, it must have a beginning Age of the Solar System • Solar system – approximately 4.6 billion years old • For natural selection and speciation to occur, this is too short a time for the processes to be successful. DNA/Microbiology • “To be or not to be” Image dropping scrabble letters to spell out this sentence! • DNA language is the same, no matter what species. If evolution is true, then DNA should have evolved every time a species evolved and it would not be the same. Blood Clotting Biochemistry Evolutionary Myths • Fossil record does not show intermediary species that prove speciation. • Adaptations do exist, but do not lead to formation of new species (Darwin’s Finches) • Embryology chart • Homologous structures