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36 Cards in this Set

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  • Back
What are Darwin's three postulates?
1. A population can expand infinitley, but the environment is finite.
2. Natural selection chooses the best adapted animals to survive
3. Variations are transmitted from parents to offspring
Similar traits in unrelated organisms
What were the 3 problems with Darwin's theory?
1. What maintains variation in a population?
2. Why do offspring seem to share characteristics from both parents?
3. How can natural selection add new traits?
What were Mendel's rules?
1. Characteristics of organisms are jointly determined by particles inherited from each parent (gene)
2. Different particles from each parent are equally likely to be transmitted to offspring
A cell divides to create two copies of itself with identical chromosomes
A cell splits in half creating haploid cells, which contain only one copy of each chromosome
Eggs or sperm
Diploid Organism
An organism that has homologous chromosomes
Haploid Cell
The result of meiosis. Contains only one copy of each chromosome
Cell which results from the unity of sperm and egg
When chromosomes get tangled and genes are shuffled around to create more variation
Linked Loci
When loci for different traits occur on the same chromosome...this means that if genes for hair color and eye color were linked, they would both either be recessive or dominate
Correlated Characters
One gene affects multiple traits
Genetic Drift
If a species becomes seperated in two small, isolated areas the gene distrubution will change and new species may evolve
Local vs. Global Optima
Natural selection selects for adaptations that are best at a specific time and place, not necessarily what is best in the long run
Hardy-Weinberg Equilibrium
The frequency of genotypes that result from reproduction will remain in equilibrium as long as there are no outside forces affecting them.
Through genetic drift, all individuals in a population should eventually become homozygous for a certain allele at a particular locus...fixation remains until population introduces a new allele
Homologous Traits
Traits which are due to shared ancestry
Analogous Traits
Traits which are due to convergent evolution
How do scientists detemine whether traits are ancestral?
1. Characteristics appear early in development
2. Characteristics appear early in fossil records
3. Characteristics that appear in outgroups
Biological Species Concept
A species is a group which interbreeds together and are reproductiveley isolated from other groups.
Reproductively Isolated
Organisms cannot breed with other groups (species) of organisms
Ecological Species Concept
Natural selection will choose the best adapted organism, regardless of whether or not there is geneflow.
Character Displacement
If two diverged species are reuinted, the derived differences will cause the two species to compete, thus they would not mate with each other.
Natural selection favors physical or behavioral changes which prevents mating between two diverged species.
Allopatric Speciation
When a species is divided by a barrier, natural selection causes the different populations to adapt to their environments and thus form different species
Sympatric Speciation
When natural selection favors different adaptations regardless of whether the species is experiencing different environments.
Adaptive Radiation
When a single species diversifies to fill many niches
Which superfamily to humans belong to?
Classification system which allows us to arrange a group of species that share a common ancestor
Why is phylogeny important?
1. It is the basis for identification of organisms
2. By comparing a species' ancestors, you can determine why certain adaptations evolved.
3. By realizing which species share common ancestors, we can better compare the features of independent species.
Construction of phylogenies
The use of phylogenies in naming and classification
Ancestrail Trait
A trait which appears early in the evolution of a lineage (was originally there, was not adapted over time)
Derived trait
Features that have evolved since the time of the last common ancestor of the species(s)
Taxonomic group that is related to the group in question