Lecture 9: slides 20 - end (Microevolution and Natural Selection)

Heredity

the passing of characteristics from parent to offspring through genes

Allele

determines distinct traits

humans inherit 2 alleles for 1 gene

2 alleles are located on the same spot of a chromosome

Genotype:

an organism’s specific genetic makeup that represents precise alleles

Gene

basic physical and functional unit of heredity

made up of DNA sequences that provide instruction to build proteins ore regulate cellular functions

Transcription

1st process of Gene Expression (DNA - RNA)

4 steps of Transcription

1) Recognize and bind

2) Transcribe

3) Terminate

4) Cap and edit

Translation

2nd process of Gene Expression (RNA - protein)

3 steps of Translation

1) Recognize and Initiate Protein Building

2) Elongate

3) Terminate

Evolution

occurs when a consequence of a certain individual in a population is born with characteristics that make them more likely to survive

Macroevolution

the change in species over time

Microevolution

the change in alleles in a population over time

Population

total # of individuals in a specific area/sharing a common characteristic(s)

5 Primary Evidence of Evolution

1) fossils - preservation

• Radiometric dating - a chemical method that detects how old bones are

2) Biogeography - where and why species live there

3) Comparative Anatomy of Embryology

• homologous structures - wing, arm, and fin

4) Molecular Biology - gene expression

5) Laboratory and Field studies - testing rats for drug efficiency

Allele Frequencies

measure how common a specific gene variant (allele) is within a population

Gene pool

the total of genetic material including all alleles and genes

Allele frequencies in a population =

Gene pool

4 Mechanisms of Evolution

1) Mutation - increase in genetic diversity

2) Genetic Drift - leads to fixation 100% and a decrease in genetic diversity/gene pool

• Founder effect - Amish and 6th finger

• Bottleneck effect - diaspora, genocide, and famine

3) Migration/Gene Flow - increase/decrease in genetic diversity/gene pool

4) Natural Selection - reproductive success

3 Satisfactory Conditions for Evolution to Occur

1) Variation for a trait - running speed in a rabbit can vary

2) Heritability - the trait of running speed is passed on from parent to offspring

3) Differential Reproductive Success - In a population, rabbits with slower running speeds are eaten by foxes, and their traits are less likely to be passed on to the next generation

Fitness

Measures # of reproductions of an individual with a particular phenotype relative to the reproduction of an individual of the same species with an alternative phenotype

• Traits with higher fitness will increase allele frequency

Adaptation

Process which organisms become better matched to their environment - also a specific feature that make an organism more fit

Measurable Effects/Modes

1) Directional - individuals with 1 extreme, from the range of variation in the population, have higher fitness

2) Stabilizing Selection - individuals with intermediate phenotypes are the most fit

3) Disruptive Selection - individuals in both extreme phenotypes have the highest fitness