AP Bio unit 7 (natural selection)

differential survival

individuals with more favorable phenotypes are more likely to survive and reproduce more offspring, thus passing traits to subsequent generations

caused by competition for limited resources

differential reproduction

Some individuals in a population lead behind more offspring than others due to advantages treat, helping them survive in causing these advantages to pass on to the next generation

evolutionary fitness

The adaptations that help an organism fit the environment better to survive and reproduce, and is measured by reproductive success

convergent evolution

when similar selective pressures result in similar phenotypic adaptations in different populations or species

When two different species become more similar, but have no shared common evolution

• Evolved similar solution to similar problems

• analogous Structures

• ex: Birds and insects

geographical evidence of evolution

The distribution of species across earth corresponds with the movement of tectonic plates and continental drift over geological time

Geological evidence of evolution

Life changes overtime through the fossil evidence

physical evidence of evolution

Observable tangible remains structures that show how living things change over time

biochemical evidence of evolution

Shows that all living things share a common ancestor by comparing molecules like DNARNA and proteins across different species

mathematical evidence of evolution

Statistical and probability models that show how gene frequencies change overtime in living populations

fossil record

shows common ancestry and transition species

Can be dated by:

• The age of the rocks where the fossil is found

• The rate of decay of isotopes, including carbon 14

• Geographical data

anatomical record

shows homologous structures, analogous structures, embryology, and development vestigial structures that reveal common ancestry

homologous structure / morphological homologies

Physical features or body parts and different species that share common evolutionary ancestor, even if they now serve different functions

Result from divergent evolution where one ancestral form splits, and develops distinct modifications

Have similar underlying structural layouts or bone arrangements

analogous structures

Biological features in different species that have a similar function, but different evolutionary origins and internal anatomy

Are the result of convergent evolution

vestigial structures

Body parts or behaviors that have lost their original ancestral function through evolution

molecular record

Comparison of DNA nucleus, high sequences, and or protein amino acid sequences provides evidence for evolution in common ancestry

divergent evolution

The accumulation of differences between related population that leads to the formation of a new species

adaptive radiation

Type of divergent evolution, where many species rapidly evolved from an ancestral species usually due to new environmental pressures

artificial selection

Human caused evolution

population

A localized group of individuals capable of interbreeding and producing fertile offspring

locus

The location of a gene on a chromosome

gene pool

Consist of all the leads for all loci in a population

polymorphism

Coexistence of two or more distinct forms of individuals (Morphs) Within the same population

Geographic variation

Differences between gene pools of separate populations or population sub groups

mutation

Changes in the nucleotide sequence of DNA

genetic drift

How alle frequencies change unpredictably from one generation to the next

A nonselective process occurring in small populations

ex: bottlenecks and founder effect

bottleneck effect

A sudden reduction in population size due to a change in the environment

ex: natural disasters

founder effect

Occurs when a few individuals become isolated from a larger population

gene flow/migration

The movement of alleles among populations

selection

act on any trait that affects survival or reproduction

four effects of genetic drift

1. Is significant in small populations

2. Causes allele frequencies to change at random

3. Can lead to a loss of genetic variation within populations

4. can cause harmful alleles to become fixed

four types of selection

1. Predation selection

2. Physiological selection

3. Sexual selection

4. Artificial selection

predation selection

acts on both predator and pray

• Speed

• Behaviors

• Camouflage and mimicry

• Defenses, physical and chemical

physiological selection

Acting on body functions

• Disease resistance

• Physiological efficiency, such as using oxygen food and water

• Biochemical versatility

• Protection from injury

sexual selection

Acting on reproductive success

• Attractiveness to potential mate

• Fertility of gametes

• Successful rearing of offspring

May act in opposition to natural selection

ex: lions mane

sexual dimorphism

The condition where male and female members of the same species have distinct physical or behavioral differences beyond their reproductive organs

artificial selection

artificial breeding can use variations in populations to create vastly different breeds and varieties

ex: Selective breeding

heterozygote advantage

Occurs when heterozygotes have a higher fitness then do both homozygotes

three modes of selection

1. Directional selection

2. Disruptive selection

3. Stabilizing selection

directional selection

favors individuals at one end of the phenotypic range

disruptive selection

Favors individuals at both extremes of the phenotypic range

stabilizing selection

Favors intermediate variance and acts against Extreme phenotypes

four reasons why natural selection cannot pass perfect organisms

1. Selection can act only on existing variations

2. Evolution is limited by historical constraints

3. adaptations are often compromises

4. Chance, natural selection, and environment interact

Hardy Weinberg principal

Describes a population that is not evolving

States that frequencies of alleles and genotypes in a population or remain constant from generation to generation

A model for describing and predicting a legal frequencies in a non-evolving population

mendelian inheritance

Preserves genetic variation in a population

conditions for Hardy Weinberg equilibrium

1. Large population size

2. No mutations

3. Random mating

4. No natural selection

5. No gene flow/migration

Hardy Weinberg equation

Calculate a little frequencies in a population from genotype frequency

p²+2pq+q²=1

p=q=1

p² & q² Represent the frequencies of the homozygous genotypes ( Each represent frequency of one allele in the population)

2pq represents the frequency of the heterozygous genotype

three factors that altered allele frequencies and bring about most evolutionary change

1. natural selection

2. Genetic drift

3. Gene flow/migration