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33 terms

Evolution Set 2

Relative dating
a technique used to determine which of the two fossils is older
Absolute dating
a techinque used to determine the age of a fossil
radioactive dating
an unstable chemical element that decays, or breaks down , into a different element or elements
half life
the length of time needed for half the atoms of a radioactive isotope to decay
fossil record
the millons of fossils that scientists have collected
relative dating
- rock layers on bottom are older than rock laers on top
- organisms in deeper layers are older than organisms in shallow layers
- the actual age of an organism and/ or rock can be determined by calculating the ratio of radioactive istope to stable material present in a sample
index fossils
fossils that are easy to identify and that we know the age of (because of radioactive dating) can be used to determine the age of a rock of any fossil
geologic time scale
-based on major organisms that dominated in the past
-eras and periods are major divisions
comparative anatomy
structural similarities link related species
-structures analogous/ homologous
analogous structure
-different ancestors
-"analogy"= like
-different underlying structures
-same function
-similar environment
homologous structure
-same ancestor
-"homo" same
-same underlying structure
-different functions
-difffent environments
comparative embryology
similar embryo development in closely related spaces
comparative biochemistry
-similar DNA sequences
-similar gene segments of the DNA
-code for similar traits
-in closely related spaces
plate techtonics
-geological theory
-continental masses that were one land mass that explains
-closely related species have common ancestors on now seperated continents
group of interbreeding individuals that live in the same place at the same time and compete with each other for food, water, and shelter
gene pool
all the genes present in a population
relative frequency
precentage of individuals with a particular allele
natural selection
goverened by genetics- the change in relative frequency of a gene in a given population leads to a change in population and may result in a new species
-DNA replication mistakes
-chemicals in the environment
-gene shuffling from sexual reproduction
directional selection
when individuals at one end of the curve have higher fitness than individuals in the middle or other end
stabilizing selection
when individuals near the center of the curve have higher fitness than individuals at either end of the curve
disruptive selection
when individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle
Hardy- Weinburg Principle
the allele frequency will remain constant if:
- there is random mating
-the population is large
- no movement in or out of the population
- no mutations
- no natural selection for or against any trait
genetic drift
changes in the gene pool due to:
- random mating
- over a long period of time
-no immigration of males and females
- no migration od males and females
- no natural selection for or against any trait
-over time
-new species
-by isolation
- natural barriers
geographic isolation
separation of organisms by geographic features
- lakes, oceans, rivers
-(may result in new species over time)
reproductive isolation
when two different species cannot mate and have successful offspring
-geographic barriers
-anatomy or physiology
-social behaviors
reproductive isolation
two organisms cannot mate
- separated by geographic boundaries
-anatomical differences
- physiological differences
-social behaviors
small changes over a long time
punctuated equilibrium
large changes happen rapidly- periods of no change
adaptive radiation
evolution of many branches of organisms from a single soure
-branch off
-homologous structures
-same origin
- same underlying structure
-different funcions
-come together
-analogous features
-from different origins
- similar environments
-similar functions
-different structures