Evolution Flashcards
Evolution
The change in the genes of a population on Earth over time
Microevolution
The changes in one gene pool of a population over generations
Macroevolution
Refers to speciation, the formation of an entirely new species
Population
Consists of all the members of one species in one place
Ex: All lions on Masai plain in Kenya
Evidence of Evolution
Fossil Record, Comparative Anatomy, Comparative Biochemistry, Comparative Embryology, Molecular Biology, Biogeography
Types of Natural Selection
Stabilizing Selection
Disruptive/Diversifying Selection
Directional Selection
Stabilizing Selection
Favors more common intermediate forms & eliminates numbers of extremes
Diversifying or Disruptive Selection
Increases numbers of extreme types in a population
Directional Selection
Changing environmental conditions
Sources of Variation in a Population
Mutation, Gene Flow, Genetic Drift - Bottleneck effect & Founder Effect
Population Stability:
Hardy-Weinberg Equilibrium
Developed a theorem describing a stable, non-evolving environment - allelic frequency does not change
Species
A population whose members have the potential to interbreed in nature & produce viable, fertile offspring
Isolation
Geographic Isolation, Polyploidy, Habitat Isolation, Behavioral Isolation, Temporal Isolation, Reproductive Isolation
Patterns of Evolution
Divergent Evolution, Convergent Evolution, Parallel Evolution, Coevolution, Adaptive Radiation
Divergent Evolution
When population gets isolated from rest of species
Homologous struture
Convergent Evolution
Unrelated species occupy same species
Analogous Structures
Parallel Evolution
Two related species, similar evolutionary adaptions after divergence from common ancestor
Coevolution
Two interacting species with mutual evolutionary set of adaptions
Adaptive Radiations
Emergence of numerous species in same environment from common ancestor
14 finches in Galapagos Islands
Theories About Evolution
Gradualism, Punctuated Equilibrium, Spontaneous Generation
Heterotroph Hypothesis
Theory that the first cells on Earth were anaerobic, heterotrophic prokaryotes
Modifications; animals to land
Lungs, skin, limbs, shell, mechanism for internal fertilization
Modifications; plants to land
Roots, vascular tissue, waxy molecule, seeds, supporting cells
Permian Mass Extinction
Volcanic eruptions, now Siberia
Eruptions emitted CO2 into atmosphere - global climate increased 6 degrees
Cretaceous Mass Extinction
10km wide asteroid crashed into Mexico
Huge cloud of debris blocked sunlight for months
Extinction of many marine & land animals + all dinosaurs, excluding birds
Important Concepts of Evolution
Evo. is not always a slow process
Evo. does not occur at same rate in all organisms
Evo. does not always cause organisms to become more complex
Evo. occurs in populations, not individuals
Evo. is directed by changes in the environment
Fossil Record
Reveals existence of species that have become extinct or have evolved into other species
Comparative Anatomy
Organisms that have similar anatomical structures are related to each other & share a common ancestor
Homologous Structures
Same internal bone structure, function of each varies
Analogous Structures
Same function but not the same underlying structure
Vestigal Structure
Structures that are remnants of an earlier active structure, such as appendix
Evidence that animals have evolved
Comparative Biochemistry
Organisms that have a common ancestor will have common biochemical pathways
Comparative Embryology
Animals that have evolved from a common ancestor go through similar stages in their embryonic development
Molecular Biology
Comparison of the amino acid sequence of cytochrome c among different organisms shows which are most closely related
Biogeography
Supercontinent Pangea separated into seven continents
Industrial Melanism
Darkening due to industrialization
Mutation (Evolution)
Changes in genetic material & are the raw material for evolutionary change
Genetic Drift
Change in the gene pool due to chance
The Bottleneck Effect
Genetic Drift
Natural disasters reduce size of population non-selectively, resulting in loss of genetic variation
Founder Effect
Genetic Drift
Small population breaks away from larger to colonize new area
Rare alleles may be under or overrepresented
Gene Flow
Movement of alleles into or out of a population
Hardy-Weinberg Characteristics of a Stable Population
Pop. must be very large Pop, must be isolated Must be no mutations in the pop. Mating must be random Must be no natural selection
Sources of Variation in a Population
Mutation, Genetic Drift (Bottleneck + Founder Effect), Gene Flow
Geographic Isolation
When species are separated
Polyploidy
Mutation that results from errors during meiosis
Can only breed with polyploid organisms
Habitat Isolation
When 2 organisms live in the same area but encounter each other rarely
Behavioral Isolation
When 2 animals become isolated from each other because of some change in behavior by one member or group
Temporal Isolation
Time
Some plant flower in cooler part of season while other plants flowers in warmer part of growing season
Reproductive Isolation
Closely related species unable to mate because of anatomical incompatibility
Theory of Endosymbiosis
Cell organelles, like mitochondria, were once tiny, free-living prokaryotic organisms that took up permanent residence inside larger prokaryotic cells
Cambrian Explosion
Period of time when every major phylum of animal appeared
Autotrophs
Organisms that make their own food
Heterotrophs
Organisms that must take in all their nutrients
