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Glossary of Biology: EVOLUTION

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Gene Duplication
(mutation)
-occurs in cell division when the chromosoms do not crossover equally

-this causes more than one copy of the genes to be inserted in the genome

-this DNA creates duplication copies of genes that are usless but are susceptible to change and mutation



Genetic Drift
-genetics can measure how frequently an allele shows up in a population

-allele frequency

-when the allele frequency changes as a result of chance this is called genetic drift

ex: 5 in a population of 50 frogs can carry an allele for white spots. If severe weather wipes out half the population we might find that all drogs with the white spot allele dies. This would cause the inheritable trait to disappear. If they survive the white spot allel could become more frequent





Artificial Selection
-selective breeding

- selecting offspring of organisms with desirable traits and breeding them

-those with more desriable traits would survive



Homologous
-structures that share a common origin but different function

-similar bones in similar positions

ex: human hands are for grasping, moles claw are for digging



Analogous
-structures that are similar in function but have no shared origin or anatomy

ex: wings of a birds and bees are not similar in structure but serve the same purpose

Vestigial
-structures that serve no useful function

ex: wisdom teeth

Erasmus Darwin
(1731-1802)
-all life may have a single source
Chevalier Lamarack
(1744-1829)
-environment plays a key role in evoluation

Theory of Acquired traits: changes acquired as a result of adaptation to the environment conditions could be inherited by future generations

Theory disproven: environment can drive evoluation but acquired traits can\'t be inherited



Charles Darwin
(1831)
-Natural Selection
George Buffon
(1701-1788)
-species could change over time and these species create new ones
Radiometric Dating
-radiisotopes are atoms that give off radiation as they break apart or decay

- the rate of decay can be measured accurately

- time required for a quantity to fall to it\'s half life as measured at the beginning of the time period

ex: Uranium from 204g to 102 in 713 million years





Sir Charles Lyell
(1797-1875)
Uniformitarianism:

-the earth underwent and continues to undergo slow gradual change

-erosion, sedimentation



Stabilizing Selection
-occurs when most common of the traits (allels) in a population are favoured by the environment

ex: most babies are born weighing a bit over 3kg. Babies under this can develop mental premature and risk death. Those over this often suffer birth trauma

Insertion of Deletion Mutation
-part of the DNA code is deleted or a new code is inserted

-mostly harmful

Sexual Dimorphism
-striking difference in gender
Sexual Selection
-the selection of any trait that favours a trait that will improve the mating success of an individual
Disruptive Selection
-occurs when individuals with traits of opposite extremes are favoured. The environment may favour more than 1 trait
Directional Selection
-occurs when the environment favours more extreme variation in a population. This can happen when organisms migrate to a new habitat where they encounter new forces of selections

ex: the pepper moth changing to melanic mmoths after pollution covered trees with black soot

Cumulative Selection
- allows the more complex traits to evole

ex: stages of eye complexity in mollusks

Speciation
-evolutuonary formation of a new species

-when changes occur in a psecies this is called microevoluation

Microevolution
-occurs when there are changes in the allele frequency and traits of a population within a species
Reproductive Isolating Mechanisms
-any behavioural, structural or biochemical trait that prevents organisms (of differnt species) from successfully reproducing
Ecological Isolation
-organisms of differeny species live in different habitats to prevent breeding

ex:woodchuck is closely related to the marmot but they live in different fields

Temporal Isolaton
-organisms are reproductively mature at different times

ex: plants bloom in different seasons

Behavioural Isolation
-organisms have distinct mating rituals to attract organisms of the same species

ex: male jumping spiders may not attract different species of female spider

Mechanical Isolation
- a structural difference in reproductive organs that prevent intercourse

- shapre of anthropod\'s penis are different even if species are closely related

Gametic Isolation
- the prevention of fertilization

-sperm and eggs of different species do not recognize each other

Zygotic Mortality
-no zygotes or embryos mature
Hybrid Inviability
-hybrid offspring are unlikely to live long
Hybrid Infertility
-hybrid offspring are sterile(mule)
Natural Selection
-al species have inherited variations of taits

-those with more favourable traits will produce more offspring that are likely to survive

-these traits will be passed on to future generations



Genetic Variation
-Genes aer located at certain positions or(loci on chromosoms
-genese come in different forms called allels

ex:you may have brown eyes but you might carry a gene for blue eyes


Neutral Variation
-one that has no effect on the reproductive success of an individual
Harmful Mutation
-one that reduces the reproductive success of an individual, causing gene malfunction and affecting cell division
Beneficial Mutation
-one that increases reproductive success causing improvement in gene function
Point Mutations
-can cause a neutral mutation if it occur s in an nn-coding area of the DNA

-can cause harmful mutations if it occurs in coding area and affects it negatively

-can cause benefical mutation if it occurs in a coding area and affects it positively



Behavioural Changes
-differences among male and females

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