Evolution of Populations

 

v  Evolution

 

 

v  By studying microevolution, we can test concepts of evolution that we cannot witness in our lifetimes.

o   Microevolution focuses on single populations.

o   Examples: guppy experiment, house sparrow size, mosquito response to global warming trends, bacterial resistance to antibiotics, insect resistance to pesticides

v  Individuals differ from each other because they have different alleles for genes that influence their outward appearance.  Let’s review some of the basic terms in genetics that will be relevant to our discussion. 

o   Chromosome: an elongated structure found in the nucleus of a cell; composed of DNA packaged with proteins

o   Gene: a segment of DNA within the long DNA molecule of the chromosome; most genes contain instructions for the synthesis of a single protein or protein subunit. 

o   Allele: alternative versions of a gene

o   Trait: feature of an organism such as height, flower color, chemical structure of a protein, etc.  Traits are specified by genes. 

o   Genotype:

o   Phenotype:

v  Evolution can be influenced if some individuals reproduce at a higher rate than others, and often differential reproductive success is based on inherited traits.  Example: TTX concentrations

 

 

 

v  Mechanisms of Evolution

o   Natural selection:

 

§  Adaptation:

 

§  3 types of Natural Selection:

·         Directional:

 

 

·         Stabilizing:

 

 

 

·         Disruptive:

 

 

 

§  Sexual selection:

 

 

 

o   Mutation:

 

 

 

o   Gene flow:

 

 

 

o   Genetic drift: