Chapter 10: Evolution Flashcards
evolution
-change in allele frequencies in a population
measuring age
- radiometric dating
- paleomagnetic dating
old conditions of Earth
- no free oxygen until cyanobacteria, leading to the Cambrian Explosion
- carbon, nitrogen, water
- lightning and U.V. radiation provided energy
homologous structures
- same structure, different function
- reflect common ancestry
analogous structures
- different structure, same function
- shows adaptation to similar environments
vestigial structures
-no longer useful (appendix)
adaptive radiation
- animals adapt and fill every available niche
- emergence of numerous species from a common ancestor introduced into an environment
Hutton
-gradualism: Earth was molded by gradual change
Lamarck
-inheritance through use and disuse
directional selection
-favors one extreme (antibiotic resistance)
diversifying selection
-favors 2 extremes
stabilizing selection
-favors individuals in the middle
balanced polymorphism
-one population divided into 2 types
sexual dimorphism
-difference in appearance between males and females
sexual selection
-selection based on variation in secondary sexual characteristics related to competing for mates
cline
-graded variation in phenotype of an organism
frequency-dependent selection
- AKA minority advantage
- decrease frequency of common phenotypes
genetic drift
-change in a gene pool due to chance
bottleneck effect
-natural disasters that reduce the size of a population unselectively, resulting in the loss of genetic variation
founder effect
- small population breaks away from old population to colonize a new area
- alleles are not represented equally
gene flow
- movement of alleles in and out of a population
- increases diversity
Hardy-Weinberg conditions for no evolution
- population must be large
- isolated from other populations
- no mutations
- mating random
- no natural selection
species
-population whose members have the potential to interbreed and produce viable,fertile offspring
reproductive isolation
- prezygotic: habitat, temporal, behavioral, mechanical, gametic
- postzygotic: hybrid sterility, hybrid inviability (dies), and hybrid breakdown (eventually becomes more weak or sterile through generations)
speciations
-creation of new species
allopatric speciation
-caused by geographic isolation
sympatric speiation
- no geographic barrier
- polyploidy
- habitat, behavioral (nocturnal vs. daytime), temporal (become sexuallymature in different seasons), and reproductive isolation
polyploidy
-more than 2 complete sets of chromosomes, can form from nondisjunction (no separation of homologous chromosomes, leading to 4n etc.)
convergent evolution
-unrelated species occupy the same environment, leading to similar adaptations
parallel evolution
-2 related species that have similar evolutionary adaptations after their divergence from a common ancestor
coevolution
-influence of two interacting populations on the evolutionary history
punctuated equilibrium
- popular theory of evolution
- new species appear after long periods of stasis
Miller and Urey
-proved that organic molecules formed in early conditions
anaerobic hetertrophic prokaryotes
-first cells on earth
endosymbiosis
- chloroplast and mitochondria have their own DNA
- DNA C and M is more like prokayotic DNA than eukayotic (not wrapped with histones)
- have double membranes (inner belongs to symbiont, outer belongs to host plasma membrane)
