Biology: EVOLUTION
Terms
undefined, object
copy deck
-
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