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LD BIO CH 29

LD BIO CHAPTER 29 THE MODERN THEORY OF EVOLUTION

TermDefinition
TWO THEORIES OF EVOLUTION Gradualism & Theory of Punctuated Equilibrium
GRADUALISM Evolution proceeds steadily over time.
PUNCTUATED EQUILIBRIUM Short periods of rapid evolution (dotted lines) and then long periods of time with little or no change
JEAN BAPTISTE LAMARCK Believed that species evolved from preexisting species. (ex: Use and Disuse Theory and Inheritance of acquired characteristics)
USE AND DISUSE THEORY If an organ is used it will be strong and powerful, however, if not used it will wither away. (Ex: muscled not used become smaller and weaker)
INHERITANCE OF ACQUIRED CHARACTERISTIC Ex: A duck developed webbed feet b/c they were needed form swimming and were passed on to offspring.
LAMARCK'S THEORY Giraffes had short necks and they stretched their necks to reach good. Giraffes that stretched their necks passed on their long neck traits to their offspring. (USE AND DISUSE THEORY)
AUGUST WEISMANN German Biologist - that disapproved Lamarck's Theory. His experiment cut off 20 generations of mice tails and all mice had the same length tails as the F1 generation.
ACQUIRED CHARACTERISTICS Do not affect the genes that are carried by the gametes.
CONCEPT OF ADAPTATION Any kind of inherited trait that improves the chances of survival and reproduction for an organism. Although Lamarck was not correct in his theory, he introduced this concept.
CHARLES DARWIN Son of a physician, found his real interest in observing the natural environment and collecting specimens. "Origin of Species". He knew that the Earth changed over time. Noticed that each species changed over time as well. (ex: Galapagos Island)
DARWIN'S THEORY Giraffes varied in neck lengths. When the environment changed only the long necked giraffes could reach food. Short neck giraffes died. Leaving only long necked giraffes to survive and reproduce.
THOMAS R. MALTHUS Wrote an essay on population. Population grow more rapidly than the food available to feed them.
THEORY OF NATURAL SELECTION The process whereby organisms with favorable variations survive and produce more offspring than less well-adapted organisms. (1858)
OVERPRODUCTION Species tend to produce too many offspring for the available food and other necessities of life.
COMPETITION To overproduction, there is a struggle for existence for space, food, water & other limited resources. (ex: 2 seedlings struggling for light, water, & minerals)
VARIATION Members of a population show differences in traits that may make individuals better adapted to survive and to reproduce. (Inheritance of Variations)
NATURAL SELECTION Nature selects most genetically favorable individuals that can adapt to changing environment (survival of the fittest). Organisms that cannot survive die.
ORIGINA OF NEW SPECIES Favorable adaptations accumulate in the species and unfavorable ones disappear. Eventually the accumulated changes become so great that the new species arise (speciation)
WEAKNESS OF DARWIN'S THEORY He did not explain how variations arise. He did not know about Mendel.
ADAPTATION Any kind o inherited trait that improves the chances of survival and reproduction for an organism
BEHAVIORAL ADAPTATION How animals act (Ex: Mating behavior, migration of birds, spawning of fish, & hibernation of animals)
STRUCTURAL ADAPTATION Involve the body of an organism. (Ex: wings of a bird and insects are adapted to flight, fins of fish and webbed feet of ducks are adaptation for swimming)
CAMOUFLAGE Protective adaptation that enables an organism to visually blend into the environment (ex: Chameleon's and octopus blend into their environments)
PHYSIOLOGICAL ADAPTATION Involved the metabolism of an organism. (Ex: Protein web made by spider, poison venom made by snakes and colorful frogs, bears metabolic rate and temperature decreases during winter hibernation allows the animals to survive long, cold periods)
WARNING COLORS Some organisms have bright colors that tells predators to stay away (Ex: Monarch Butterfly, Poison Dart Frog) OR an organism resembles another to avoid predators (Ex: Milk Snake Mimics the coral snake)
HARDY-WEINBERG PRINCIPLE Gene frequencies remain constant from generation to generation if under these conditions: large populations, absence of mutations, absence of migration (in or out), random mating & any condition opposite of this promote change in the gene pool.
GENE FREQUENCY The number or indicating the ratio of a gene to its other alleles in a gene pool.
ADAPTED RADIATION The process by which a species evolves into a number of different species, each occupying a new environment.
REPRODUCTIVE ISOLATION The loss of the ability to interbreed by two isolated groups.
REPRODUCTIVE ISOLATION FACTORS Different reproductive organs or courtship patterns, differences in chromosomes may prevent pairing of chromosomes during fertilization, & females produces eggs at a time when sperm is not fertile.
GEOGRAPHIC ISOLATION The first stage of speciation, in which a population of organisms is prevented from interbreeding with other populations of that species by a natural barrier. (Barriers include mountains, canyons, rivers, highways, climate and even other organisms)
DIRECTIONAL SELECTION A type of natural selection in which an extreme phenotype becomes a favorable adaptation. Usually operates when environment changes or species migrate. New environment favors extreme phenotypes.
THREE FORMS OF SELECTION Directional, Stabilizing, & Disruptive
STABILIZING SELECTION The average phenotype is favorable and extreme phenotypes are unfavorable. (ex: mice too small may not be strong enough to burrow underground and large mice may use too much energy to keep warm)
DISRUPTIVE SELECTION Two opposite phenotypes are favorable & the average phenotype is unfavorable. (Ex: light tan & dark brown crabs can survive in new environment while white mid range colors cannot camouflage against predators).
Created by: desilva13
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