Evolution Flashcards
population
individuals of the same species that are living in the same area at the same time
individuals do not
evolve
evolutionary processes act on
populations
darwin noticed that species in temperate south america more similar to
species in tropical south america than species in temperate europe
darwin noticed species on Galapagos were
endemic, specific to island, but similar to mainland animals
darwin noticwed flora and fauna
varies island to island
darwins hypothesis after the Beagle voyage
animals on islands originate from mainland and underwent change
lamarck
though species change was always progressive and inheritance of acquired characteristics
darwin and lamarck
darwin agreed that species aren’t static, but disagreed on mechanism of change
lyell
uniformitarianism - earth shaped by slow processes that still happen, so study processes to understand the past
darwin and lyell
can slow processes also impact the natural world
cuvier
catastrophism - earth shaped by rapid, violent events that cause mass exntinctions (didnt believe in evolution tho)
darwin and cuvier
agreed with cyclic extinctions, lead him to believe that different species lived at different times
malthus
populations grew at faster rate than food supply so there will always be struggle to exist
malthus and darwin
resources finite, organisms struggle to exist
what pushed darwin to publish On the Origin of Species in 1859
received a letter from Wallace, who developed theory of natural selection on his own
theory of evolution has two components
patterns and processes
patterns
descent with modification
descent with modification based on observations of
change over time and species alive today descended from species in past
process
mechanisms that cause the patterns
process that was apparent during Darwin’s time
natural selection
natural selection
increased survival/reproduction of some individuals because of certain traits in a certain environment
processes that came after Darwin’s time
genetic drift, gene flow, mutation
4 points evidence of species change over time
earth is 4.6 billion years old, 99% of species that ever lived have gone extinct, living species resemble fossil species in same region, vestigial traits
radiometric dating
used to find age of rock layers
first signs of life occur
3.7-4.3 billion years old, microfossils
darwinian trickle
low constant level of extinction
transitional form/features
show change and species development over time
vestigial traits
reduced or incompletely developed traits found in living organisms, that have no/reduced function but are similar to functional traits in other species
2 points evidence of descent from common ancestor
closely related species live in same geographical area, homologous traits
example of closely related species in same geographical area
Galapagos mockingbirds are unique to each island but similar to each other - all descended from mainland bird
homologous trait
similar in DNA, RNA, or amino acid sequence
example of homologous trait
Pax6 gene in mouse - for eye development locator - has different DNA homolgy with similar genes in other species, but 100% protein homology
developmental homology
similarity during development, such as gill pouch
structural homology
similarity in structure, such as 1-2-many bone organization in limbs
artificial selection
breeders can select for specific traits
darwins first posulate for natural selection
individuals in population do not look alike (variation exists)
darwins second postulate
some of the trait differences are heritable
darwins third postulate
resources are finite - struggle for existence
darwins fourth postulate
some variants will survive and reproduce better than others
fitness
ability to survive and produce viable offspring relative to others in the population
measure fitness by
counting and comparing number of surviving offspring
adaptation
heritable trait that increases fitness
neo darwinism
fusion of work by darwin, mendel, population genetics, paleontology, geology, cytology
mutations lead to
variants
evolution
change in frequency of variants in a population due to natural selection, mutation, gene flow, genetic drift
natural selection cannot happen continuously because it would
eliminate variation
acclimatization
change in phenotype of an individual that occurs in response to environment (acclimatization does not equal adaptation)
why doesn’t evolution perfect traits
some traits subject to genetic/historic constaints such as beaks for large seeds
pleiotropy
single allele affects multiple traits
