Chapter 21 Flashcards
Natural Selection
Variation in traits
Genetic component/heritable
Passing on good alleles more than bad alleles
Phylogenetic tree
Grouping based on similar or difference
Evidence of Natural Selection
3 Conditions
Variation must exist in population
This variation must lead to differences among individuals in reproductive success
Variation among individuals must be genetically transmitted to the next generation
Evidence in natural selection
Peter and Rosemary Grant medium ground finch beak in droughts
(big beak) and normal rain (decreased/ normal size)
Peppered moths and industrial melanism. Black dominant allele. Tutt hypothesis tested by Kettlewell
Artificial selection
Laboratory experiments Drosophila melanogaster (fruit fly) 86 generations later quadrupled bristles but also disruptive pattern
Corn, silver foxes, dogs
Fossil evidence of evolution and 3 events to create fossil
Fossils are the preserved remains of once living organisms, created when 3 events occur
1 Organism buried in sediment very quickly (Tar pits, resin)
2 Calcium in bone or other hard tissue mineralizes quickly
3 Surrounding sediment hardens to for rock
Fossils are rare.
Archaeopteryx -intermediate between bird and dinosaur, transitional species
Absolute dating vs Relative dating
Absolute - age of fossils is estimated by rates of radioactive decay (abundance of isotopes)
Relative - position of the fossil in the sediment, the deeper the older
Anatomical evidence for evolution
Homologous vs Analogous
Strongest evidence supporting evolution cones from comparisons of how organisms develop. Early vertebrate embryos possess pharyngeal pouches that turn into glands and ducts or gill slits
Eyes Mollusks photoreceptors face forwards and vertebrates face backwards
Vestigial structures - have no apparent function, but resemble structures their ancestors possessed
Convergent evolution
Biogeography - the study of the geographic distribution of spp, some plant and animals have similar appearance but are only distantly related.
Convergent evolution - the independent development of similar structures in organisms that are not directly related. It is usually seen in animals and plants that live in similar environments.
Marsupials young are born in an immature condition and geld in a pouch until they develop
Placentals young are not born until they can survive in the external environment (Mammals or dolphins)
Darwin’s critics/criticisms
Evolution is not solidly demonstrated
No fossil intermediates
Intelligent design arguments - organs too complex for a random process to have produced them.
Violation of second law of thermodynamics - increase in entropy
Proteins are too improbable
Natural selection cannot account for major changes in evolutions
Cellular mechanisms are so complex
