Evolution

Theory

a theory is a widely accepted and much tested explanation that ties together lots of observations in science.

Evolution

Change over time

Charles Darwin

-Father of Evolutionary Biology

-in 1831 was hired to be naturalist on HMS Beagle sailed around the world to map coasts (esp. S. America)

- whenever they put into a port Darwin got off boat and explored the lands and collected specimens

- these specimens became support for his theory of Natural Selection

Natural selection

Organisms that are better adapted survive and reproduce at a higher frequency, causing genetic change in the population.

The environment act on variation in a population, causing genetic change in the population over time

direction selection

Type of natural selection that favors one estreme form of a characteristic

disruptive selection

Type of natural selection that favors BOTH extreme forms of a characteristic

Stabilizing selection 

Type of natural selection that favors average individuals

Variation

What does natural selection act on

There is genetic variety in population. This is called____

variation

genetic equilibrium

When the frequency of allele remains the same over generations

No evolution is occurring if a population is in _____

 genetic equilibrium

population

Members of the same species that inhabit a specific place and are able to interbreed to produce fertile offspring

Allele

Alternative form of a gene

gene pool

All of the alleles and characteristics that are found in a population

All of a population genes

Allele frequency 

The percentage of a particular allele in a population

Mutation

Any change in Dna sequence

The source for new alleles and traits that natural selection can act on

natural selection

Mechanism that produces evolution by acting on phenotype variations

Non random mating

Choosing mates based on preferred characteristics

Gene flow

Movement of individuals into and out of a population

Immigration and emigration

Genetic drift

Random events that cause changes in allele frequencies

Especially affects small populations (examples include bottleneck and founder effect)

Emigration

Movement of individuals OUT of population

immigration

Movement of individual INTO a population

Founder effect

Type of genetic drift that is the result of a small population that leaves the main population to form its own colony with a distinct gene pool

The foundation of a new colony that is by chance different genetically from the original population

bottleneck

Type of genetic drift that is the result of a chance event like a catastrophic hurricane

“A natural disaster dragster drastically reduces population size and alter allele frequencies”

speciation

Process by which new species arise…The key is reproductive isolation

What has occurred if two population of penguins become unable to interbreed with one another?(Reproductive isolation)

 behavioral isolation

Different courtship behaviors/signals among species

The albatross “mating dance” is not attractive geese

Seasonal isolation 

If two species are reproductively isolated because they breed at different times

Polyploidy

multiple sets of chromosomes that cause plants to be unable to interbreed with owners that have normal numbers of chromosomes

Geographic isolation

when a physical barrier such as a river or mountain range divides a population

mechanical isolation

physical incompatibility of two species that leads to reproductive isolation

a certain flower has a shape that allows for pollination by

hummingbirds but another flower has a shape that does NOT allow for pollination by hummingbirds.

Punctuated equilibrium

Theory that evolution occurs in fast bursts followed by long periods of genetic equilibrium

gradualism

Theory that evolution occurs due to slow, gradual build-up of adaptations over time  

Convergent Evolution

A pattern of evolution in which unrelated species develop similar adaptations to their environment

Bird wings, bat wings, and butterfly wings

divergent evolution

A pattern of evolution in which species that were once similar to an ancestral species, become increasingly distinct or “diverge”

Two species of butterflies become increasingly different in color pattern over time punctuated

adaptive radiation

Evolution of a species into an array of fit a number of diverse habitats

The galapagos finches are a good example of this phenomenon. It is thought that the variety of finch types developed in order to fit into a variety of habitats

biochemistry

DNA,RNA and protein similarities between species

The amino acid sequence for cytochrome c (a protein) and the DNA sequence that codes for it are similar in a variety of species

embryology

Examining similarities in development between embryos of various species

adaptation

Any characteristic that helps and organism survive and reproduce in an environment

Examples include gills and fins in fish, sharp teeth in predators, antibiotic resistance in bacteria ect

fossils

Remnants or traces of organisms form long ago

The law of superposition, which states that deeper layers of sedimentary rock are older, relates to this line of evidence. Also, mass extinctions are observable

anatomy

Comparing the body structures of different organism

Analogous structures, homologous structures, and vestigial structures

mass extinction

A catastrophic event that results in the loss of large numbers of species(reduced biodiversity)

Analogous structures

Structures that are similar in function but different in structure and are NOt thought to be the result of close common ancestry
Bird wings and butterfly wings

 vestigial structures

Structures that seem to serve little or no function in a modern organism

Thigh bones in snakes, leg bones in whales or wings on flightless birds

Mimicry

A structural adaptation in which one species resembles another species

The viceroy butterfly looks like the bad tasting monarch butterfly and therefore avoids some predation

homologous structures

Structures that are thought to be the result of common ancestry and that are similar in structure but modified in function

The forelimb bones of whales, humans bats and other species, are very similar in structure but have different function

Reproductive isolation

When two formerly interbreeding populations are no longer able to interbreed

This produces new species (causes speciation)

Phenotype

The physical appearance or observable traits of an organism

natural selection acts on this

Camouflage

Adaption in which a species blends in with its environment

Genotype

The genetic makeup of an organism for a specific trait 

A combination of alleles such as Aa

Species

Organisms that can interbreed to produce fertile offspring