evolution Flashcards
what did Darwin and Wallas observe?
pattern
hypothesized process
what is pattern?
organisms only live in environments to which they are well adapted
what is hypothesized process?
environmental factors prevent any organism that is not well adapted from successfully reproducing (natural selection)
what is darwins theory of evolution?
variation exists among individuals of a population
variation is heritable
variation affords different traits to individuals
competition exists among individuals
variation provides material for natural selection to act on
an organism suited to its environment is more likely to survive
what is natural selection?
observable way for life to change
how are traits coded for?
by DNA which forms genes on a chromosome
characteristics of sexual reproduction?
offspring inherit genetic material from their parents
results in recombination of genetic material
new combinations in every generation
23 chromosomes for each sperm and egg
characteristics of mutation?
random in DNA
arise and can spread through a population
provide genetic variation which leads to evolution
small changes are good, large changes are harmful
types of mutations?
deletions
duplications
inversions
what is a deletion mutation?
DNA pair is removed from the strand
what is a duplication mutation?
DNA is repeated
what is an inversion mutation?
DNA bases are reversed in order
what does fitness refer to?
probability of successful reproduction
ability to survive
find a mate
produce viable offspring
what happens when the environment changes?
the traits that are beneficial also change
what does natural selection affect?
the individual
what is evolution?
a change in gene frequency within a population from generation to generation
what is selective breeding?
the ability to choose desirable traits
characteristics of large populations?
more genetic material
new traits take longer to express themselves
more variability
characteristics of small populations?
evolve rapidly
fitness traits are spread through the population more readily
less variability
vulnerable to rapid extinction
what is convergent evolution?
different structures evolved independently and differently from the same structure
what are analogous structures?
the same structure but cant be traced back to the same ancestor
what is small scale decent with modification?
changes in gene frequency in a population from one generation to the next
what is large scale decent with modification?
decent of different species from a common ancestor over many generations
what is the biological species concept?
members of a population who can breed and produce viable offspring
can be observed in nature
what is the morphological species concept?
species distinguished based on physical differences
how do we define species?
by the biological species concept
how do we differentiate species in fossil record?
by the morphological species concept
what is rapid eveolution?
nothing in between the before and after
what is gradual evolution?
can see each step and progression in the change
how do we track biodiversity in fossil record?
sum total of different taxa
affected by rates of origin and extinction
what is the origination rate?
rate at which new taxa evolve/ are found in fossil record
what is the extinction rate?
the rate at which taxa go extinct through geologic time
end of a genetic lineage
what are mass extinctions?
when the extinction rate increases exceeds the origination rate
what do mass extinctions result in?
a decrease in global biodiversity
