Terms in this set (57)
What is Evolution
the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.
An educated guess
well-tested explanation that unifies a broad range of observations
proposed that the Earth is shaped by geological forces over extremely long periods of time, and that the Earth is very old
Proposed changes in the environment causes use/disuse of specific organisms
Small changes on Earth's surface have gradually occurred over long periods of time
Different traits of an individual in the group it belongs
A trait that helps an organism survive and reproduce
when humans determine which individuals breed, typically with a preconceived set of traits in mind
Four conclusions Darwin made about how evolution occurs
1. Struggle for survival exists in nature
2. Certain variations allow individuals to survive better in an environment
3. Over long periods of time, natural selection produces organisms that have different structures, establish different niches, or occupy different habitats
4. Genes contain multiple alleles. often several alleles and organisms can have hidden alleles.
survival of the fittest
Process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection
Descent with modification
Each living species has descended over time with changes from other species over time.
5 Main sources of evidence to support the theory of evolution
1. Fossil Record
2. Geographic Distribution of Living Species
3. Structural Similarities of Related Life Forms
4. Chemical Similarities in DNA
How does the fossil record provide evidence for evolution?
It shows how organisms have evolved over time
Relative Age Dating
Age determined by comparing placement with that of fossils in other layers of rock
Radioactive Age Dating
Assigns specific age to fossil
Similar but unrelated organisms live in different locations due to different lines of evolutionary descent.
Structures that have different mature forms in different organisms but develop from the same embryonic structure(Same development, different structure)
Organ that serves no useful function in an organism
Structures that evolve separately to perform a similar function
How Do Chemical Similarities Support the Theory of Evolution?
All proteins are coded through 20 types of Amino Acids
How do embryos support evolution?
Embryos look similar during early summer development
A population is a group of individuals of the same species that interbreed.
Consists of all the genes including all the different alleles that are present in a population
Two main sources of genetic variation
Mutations: Any change in the sequence of DNA
Recombination: Natural formation of genetic combinations in offspring not present in parents.
What does a normal distribution of traits show us
Bell Curve: Frequency of phenotype is highest at mean value and decreases near end.
Takes place when individuals at one end of the curve have higher fitness than peeps in the middle and the other end.
Individuals near the center of the curve have higher fitness than individuals at either end
Takes place when individuals at the upper and lower ends of the curve have higher fitness than the individuals near the center.
Movement of alleles from one population to another
What is gene flow affected by?
Affected by mobility, barriers, and environment.
Random changes in allele frequencies that occur in a small population
A change in allele frequency following a dramatic reduction in the size of a population
Change in allele frequencies as a result of the migration of a small subgroup of a population
What does the Hardy-Weinberg equilibrium describe?
populations that are not evolving
5 conditions required to maintain genetic equilibrium
1. Random mating
2. The population must be very large
3. There can be no movement in and out of the population
4. There can be no mutations
5. There can be no natural selection
Whats the Equation
Frequency of homozygous dominant genotype (AA)
Frequency of heterozygous genotype (Aa)
frequency of homozygous recessive genotype (aa)
Frequency of A
Frequency of a
Formation of new species
A group of similar organisms that can breed and produce fertile offspring.
Separation of species or populations so that they cannot interbreed and produce fertile offspring
3 types of reproductive isolation
Behavioral, geographic, temporal
Technically able to reproduce but have different ways to mate(Different mating calls)
Form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water
Form of reproductive isolation in which two populations reproduce at different times
5 Patterns of evolution
2. Convergent Evolution
3. Divergent Evolution
5. Punctuated Equilibrium
A term that typically describes a species that no longer has any known living individuals.
Process by which unrelated organisms independently evolve similarities when adapting to similar environments
the process by which two or more related but reproductively isolated populations become more and more dissimilar(homologous)
The theory that evolution occurs slowly but steadily
evolution happens in spurts rather than being steady
Process by which two species evolve in response to changes in each other
Gradualism vs. Punctuated Equilibrium
Gradualism is the idea that organisms change gradually and steadily over time, punctuated equilibrium is equilibrium that is interrupted by brief periods of more rapid change