Evolution Chapter 15
Two schools of thought Creation – God worshipping people Evolution – atheist
Creation vs. Evolution CreationEvolution DefinitionGod created everything in the universe Change of organisms over a long period of time Time of Earth’s existence More than 4,000 years 4.5 billion years Life started withGod made animals, plants, and people A single cell organism
Creation vs. Evolution Issue # 1: The origin of the earth Creation – God (or an intelligent designer) created the heavens and earth Evolution – several ideas (have not decided on one theory) Solar nebular theory – Hydrogen and helium came together to form stars. When stars die, they explode releasing clouds of gas and dust. The dust started to stick together. Over millions of years, they formed planets.
Creation vs. Evolution
Issue # 2: People believed the earth was flat Columbus “proved” that the earth is round in the 15 th century Isaiah 40: states that the earth has a circular shape
Evolution Evolution – a change in an organism over a long period of time Charles Darwin – the father of evolution Darwin had some proof to support his theory The shape of fossils Darwin’s time on the HMS Beagle Darwin’s trip to the Galapagos Islands Located off of South America Galapagos tortoises and Galapagos finches
Evolution Galapagos tortoises
Evolution Galapagos finches
Artificial Selection Artificial selection – breeding organisms with specific traits in order to produce offspring with identical traits Man chooses which traits organisms should have Example – dogs and cows
Artificial Selection Example – beef cows vs. dairy cows
Natural Selection Natural selection – occurs when organisms with favorable variations survive, reproduce, and pass their variations to the next generation Selection occurs on its own or “naturally” Example – birds with long tail feathers
Natural Selection Darwin called natural selection “survival of the fittest” Stronger organisms with preferred traits lived and made fertile offspring Example – Two populations of fish One population is faster than the other Natural selection would favor which population? “X” indicates faster swimmer
Natural Selection Natural selection would favor polar bears in the arctic and grizzly bears in the taiga. Why?
Adaptations: Evidence for Evolution Adaptation – any variation that aids an organism’s chances of survival in its environment Adaptations in species develop over many generations Adaptations of a frog
Adaptations: Evidence for Evolution Several forms of adaptations: Mimicry – a structural adaptation that enables one species to resemble another species
Adaptations: Evidence for Evolution Aggressive mimicry – a technique used by some animals to lure prey to them by mimicking something else Angler fish
Adaptations: Evidence for Evolution Aggressive mimicry Golden orb weaver will weave heavy zig-zag lines of web to attract insects Found in Australia
Adaptations: Evidence for Evolution Aggressive mimicry Snapping turtle’s tongue resembles a worm
Adaptations: Evidence for Evolution Camouflage – an adaptation that enables species to blend with their surroundings
Adaptations: Evidence for Evolution Warning coloration – A protection adaptation used by some animals that uses color to warn other animals to keep away Yellow jacket Poison dart frog
Other Evidence for Evolution Anatomy Homologous structures – structures with common evolutionary origins Provides evidence of evolution from a common ancestor Examples: forelimbs of lizards, whales, humans, and birds
Other Evidence for Evolution Analogous structures – structures that do not have a common evolutionary origin but are similar in function
Other Evidence for Evolution Insect Pterodactyl Bat Bird Analogous structures
Other Evidence for Evolution Vestigial structure – a structure in a present- day organism that no longer serves its natural purpose, but was probably useful to an ancestor Example: appendix
Other Evidence for Evolution Embryology – the earliest stage of growth and development of both plants and animals
Population Genetics and Evolution Evolution occurs on populations, not individuals Variation coupled with natural selection fuels evolution Gene pool – all of the alleles in a population’s genes
Population Genetics and Evolution Natural selection acts on variations Stabilizing selection –favors average individuals in a population Directional selection – favors one of the extreme variations of a trait Disruptive selection – individuals with either extreme of a trait’s variation are selected for Tends to eliminate intermediate phenotypes
The Evolution of Species Speciation – the evolution of a new species Several ways for speciation to occur: Geographical isolation – a physical barrier divides a population
The Evolution of Species Reproduction isolation – formerly interbreeding organisms can no longer mate and produce fertile offspring
Patterns of Evolution Adaptive radiation (divergent evolution) – an ancestral species evolves into an array of species to fit a number of diverse habitats Laysan finches from the Hawaiian islands
Patterns of Evolution Convergent evolution – occurs when unrelated species evolve similar traits