Transcript Evolution
Evolution Evolution- change in population over time Evolution- Darwin Darwin father of modern evolutionary theory Galapagos Islands HMS Beagle Darwin HMS Beagle Trip around the world Scientists who influenced Darwin Lamarck- organisms change due to the pressures of their environment, traits are acquired He proposed that by using or not using its body parts, an individual tends to develop certain characteristics, which it passes on to its offspring. Scientists who influenced DarwinLamarck Example: A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring. Natural Selection Natural Selectionorganisms with traits best suited to the environment survive have more offspring Natural Selection Example: Peppered Moths during the Industrial Revolution Natural Selection Extinction- permanent loss of a species 5 mass extinctions throughout history Evidence for Evolution 1. 2. 3. 4. 5. 6. Fossils Comparative anatomy Comparative embryology Biochemistry Genetic evidence Direct evidence Evidence for Evolution 1. Fossils mold or cast of organism left in rock, fossilized bone and teeth life becomes more complex over time record is incomplete Evidence for Evolution Most complete fossil record is for the horse Evidence for Evolution Relative dating layers in rock bed used to date organisms Deeper is older, shallow is younger Evidence for Evolution tell when organisms lived in reference to other organisms older organisms show simpler body structure, while more recent organisms are more complex many fossils show strong similarities to existing organisms Evidence for Evolution Radioisotope dating- uses half-life of element to estimate age of organism Carbon is used frequently Evidence for Evolution phylogenydescription of the lines of descent of plants and animals as they lived from one to the next (how they are related) Evidence for Evolution 2. Comparative Anatomy- the study of the structures of different organisms homologous parts modified structures among different groups of descendants Evidence for Evolution Comparative Anatomy Evidence for Evolution Comparative Anatomy analogous partsstructures in organisms that have no common origin but serve the same function Example: bird’s wing, bat’s wing and insect’s wing Evidence for Evolution Comparative Anatomy vestigial organs- organs having no functions in the living organism Vestigial toes in the horse Vestigial pelvis and femur in whales Evidence for Evolution Comparative Anatomy Vestigial spurs on a snake Evidence for Evolution Comparative Anatomy What vestigial organ do we have???? Evidence for Evolution 3. Comparative Embryology the study of developing plants and animals Evidence for Evolution Below is the pictures of embryos for a fish, human, rabbit, tortoise, and chicken. Can you guess which one is each type of organism? 1 2 3 4 5 Evidence for Evolution Comparative Embryology Here the pictures of the second set of development is added. Can you tell now? 1 2 3 4 5 Evidence for Evolution How about now? 1 2 3 4 5 Evidence for Evolution Comparative Embryology- The complete picture Evidence for Evolution 4. Biochemistry comparison of DNA and proteins in the body Example: comparison of hemoglobin (blood protein) in human, chimp, and dog. Human and chimp hemoglobin more alike than dog Evidence for Evolution The closer related the fewer differences in DNA and proteins Evidence for Evolution 5. Genetic Evidence Mutationsmistakes in the genetic code Causes changes in populations over time Evidence for Evolution 6. Direct Evidence Rapid Evolution Strains of bacteria becoming resistant to antibiotics Weeds and pesticides Insects and pesticide Adaptations Adaptation- change in a species that makes it better suited to its hump to store nutrition during environment Along trips or when food or water Fur inside the ears to protect inner ear from sand Nostrils that close to keep sand out Calluses on the the knees to protect from abrasion is scarce Long eyelashes to protect their eyes from the sand when the wind is blowing Large feet for standing in the sand Types of Adaptations Structural Changes in structure or anatomy Example: bird’s beak or claws Mimicry- a harmless species resembles a harmful one, predators learn to avoid both species Camouflage- species features blend in with the environment Mimicry Camouflage Types of Adaptations Physiological Changes in chemical makeup Examples: digestion enzymes, snake venom, octopus ink Types of Adaptations Behavioral Responses to the environment Example: bird migration Mechanisms for Evolution Species- group of organisms that can interbreed AND produce viable offspring Populations evolve NOT individuals Origin of a Species Common Misperception: Individuals Evolve Species evolve NOT individuals “And now there go the Wilsons!... Seems Like everyone’s evolving except us!” Mechanisms for Evolution Gene pool- all the alleles for a trait in the population Over time gene pools shift to traits that are best suited to the environment Allelic frequency- the percent of any specific gene in a population Genetic Equilibrium- when the percentage of alleles in a population remains stable over time Natural Selection acts on variation in a population 1. stabilizing – favors average individual 2. directional – favors one extreme variation 3. disruptive – favors both extremes of variation Natural Selection acts on variation in a population Stabilizing selection Directional Selection Disruptive selection Origin of Life on Earth Spontaneous generation- nonliving materials can produce life, life could be created out of nothing, from the air Disproving Spontaneous Generation Origin of Life Biogenesis- living organisms only come from other living organisms Origin of Cells Earth approximately 4.6 billion years old Beginning- earth’s atmosphere Hot, gases like CO2 and nitrogen, little O2 Gases helped to create the atmosphere Origin of Cells 3.5 to 4 billion years ago Organic Molecules Protocells Prokaryotic cells (heterotrophs) First simple autotrophs/producer Eukaryotic cells Multicellular organisms Origin of a Species Speciation – formation of a new species, members of similar populations no longer interbreed Origin of a Species Geographic Isolation Physical barrier divides population River, canyon, mtn. splits group Two species of squirrel split by the Grand Canyon Patterns in Evolution Adaptive radiation – one ancestral species evolves into a number of species to exploit a number of habitats. Patterns in Evolution Divergent evolution- one species evolves into two species with different characteristics (get more and more different from each other) Patterns in Evolution Convergent evolution – distant or unrelated species evolve similar characteristics to take advantage of similar environments Example: fish and dolphin Evolution