Evolution Flashcards
Theory of evolution by natural selection
- _____ differences between individuals in a population
- Heritable alleles produce _____ that affect the ability of an organism to survive and have offspring
- Some individuals have phenotypes that allow them___, ___, and ___
- Individuals with phenotypes allowing _____ will pass their alleles more frequently than those who do not
- Overtime, alleles leading to more offspring will become _____, while others will become less abundant in the gene pool
Theory of evolution by natural selection
- Heritable differences between individuals in a population
- Heritable alleles produce phenotypes that affect the ability of an organism to survive and have offspring
- Some individuals have phenotypes that allow them to survive longer, be healthier and have more offspring
- Individuals with phenotypes allowing more offspring will pass their alleles more frequently than those who do not
- Overtime, alleles leading to more offspring will become more abundant, while others will become less abundant in the gene pool
Evolutionary fitness
How successful individual is on passing its alleles to future generations
Two sources of genetic variation in populations
New alleles (mutations) and new combinations of existing alleles (sexual reproduction)
Directional selection
polygenic traits follow a bell-shaped curve of expression, most individuals are around the average
as one extreme, gets eliminated, the population shifts toward the other extreme
short giraffes die, so there are more tall giraffes
Divergent selection
Removes members near the average leaving those at either end.
The pop is split in two and could lead to a new species
Ex: small deer can hide and large deer can fight but medium are too big to hide and too small to fight so they die off
Stabilizing selection
Both extremes of one trait are selected against, driving pop toward the average
Ex: Birds too large and too small are eliminated because they cannot mate
Artificial selection
Humans intervene in the mating od animals and plants to achieve desired traits through controlled mating
Puppy mating
Sexual selection
Animals don’t choose mates randomly, but have evolved to rituals and physical displays to attracting and choosing a mate
Kin selection
Animals that live socially share alleles with others and sacrifice themselves for the sake of the alleles they share with another individual
A female lion sacrifices herself to save her sisters children
Species
Group of organisms capable of reproducing with one another
Reproductive isolation:
Two types
Keeps existing species seperate
Prezygotic and postzygotic
Prezygotic reproductive isolation:
Postzygotic reproductive isolation:
Pre: prevent formation of hybrid zygote via barriers
Post: prevent development, survival or reproduction of hybrid individuals / prevent gene flow if fertilization does occur
5 prezygotic barriers
Ecological: can’t mate, live in diff habitats so cannot access one another
Temporal: mate at diff times of day, season or year
Behavioral: rituals before mating
Mechanical: genital organs/structures not compatible for mating
Gametic: sperm from one species cannot fertilize the egg of another species
3 post-zygotic barriers
Hybrid inviability: hybrid offspring does not develop or mature normally / die in embryonic stage
Hybrid sterility: born and develops normally bur doesn’t produce gametes / incapable of breeding
Hybrid breakdown: two hybrids mate successfully and produce hybrid offspring but this generation is biologically defective
Cladogenesis
Creating new species from existing species
Homologous structures
physical features shared by two species as a result of a common ancestor
dog feet and human feet suggest all came from ancestor with feet
Analogous structures
serve same function in two different species but not due to the same human ancestor
flagellum of sperm and bacteria flagellum
Binomial classification system
Each organism is given two names: species and genus
Genus capitalized and species not i.e., Homo sapien
8 principle taxonomic categories and the mnemonic
Dumb King Phillip Came Over For Great Soup
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Early atmosphere was a reducing environment meaning
Electron donors were prevalent so no O2 was in the atmosphere because it is an electron acceptor
Lab recreations of the early atmosphere result in spontaneous formation of AA, carbs, lipids and ribonucleotides
Abiotic synthesis
Absence of enzymes in the early atmosphere, metal ions on the rocks surfaces and clay acted as catalysts
Proteinoids
Polypeptides made via abiotic synthesis
Microspheres
Proteinoids in water spontaneously form droplets
When lipids are added to microspheres, ___ form
Lipsomes
Coacervates
Made with preexisting enzymes capable of catalyzing reactions
Protobionists resemble cells in that they:
Contain a protected inner environment and perform chemical reactions
Can reproduce (too large: split in half)
Don’t have an organized mechanism of heredity
What makes up protobionists?
Microspheres, liposomes and coacervates
