Darwinian Fitness Measurable mathematically; is a relative not an absolute measure The ability of an individual to survive and reproduce in its present environment Natural selection Not goal oriented Does not anticipate environmental changes Increases reproductive success in the current environment Always a generation behind any changes in the environment modifes designs, that is development, anatomy, physiology, ecology, and behavior in a random way Types of Natural Selection Normal distribution Bell shaped curve Can be controlled by multiple genes controlling polygenic phenotypic traits 1- Stabilizing selection The extremes are selected against producing over subsequent generations a population with less variation, reflected in the tighter bell-shaped curve examples: cliff swallows, selection for symmetry, form in animal species 2 - Disruptive selection Individuals with intermediate features are selected against, eventually producing over the subsequent generations a divided result with two distinct phenotypes at the extremes with their own bell-shaped distributions Examples: grove snails 3 – Directional selection Selection acts against one extreme and favors the other Example: peppered moths and pollution; artificial selection pressures; finches and drought Hardy Weinberg Principle (p+q)2 = p2 + 2pq + q2 = 1 p2 = individuals homozygous for first allele 2pq = individuals heterozygous for the alleles q2 = individuals homozygous for second allele Conditions: Selection coefficients sp2(p2)+ s2pq(2pq) + sq2(q2)= 1 where S varies from 1.0 to 0.0
Darwinian Fitness Measurable mathematically; is a relative not an absolute measure The ability of an individual to survive and reproduce in its present environment Natural selection Not goal oriented Does not anticipate environmental changes Increases reproductive success in the current environment Always a generation behind any changes in the environment modifes designs, that is development, anatomy, physiology, ecology, and behavior in a random way Types of Natural Selection Normal distribution Bell shaped curve Can be controlled by multiple genes controlling polygenic phenotypic traits 1- Stabilizing selection The extremes are selected against producing over subsequent generations a population with less variation, reflected in the tighter bell-shaped curve examples: cliff swallows, selection for symmetry, form in animal species 2 - Disruptive selection Individuals with intermediate features are selected against, eventually producing over the subsequent generations a divided result with two distinct phenotypes at the extremes with their own bell-shaped distributions Examples: grove snails 3 – Directional selection Selection acts against one extreme and favors the other Example: peppered moths and pollution; artificial selection pressures; finches and drought Hardy Weinberg Principle (p+q)2 = p2 + 2pq + q2 = 1 p2 = individuals homozygous for first allele 2pq = individuals heterozygous for the alleles q2 = individuals homozygous for second allele Conditions: Selection coefficients sp2(p2)+ s2pq(2pq) + sq2(q2)= 1 where S varies from 1.0 to 0.0
Exam%203%20Study%20Guide%20(revised).docx