Chapter 3: Genetics and Evolution. Chapter 4: Human Variation. Flashcards
(21 cards)
The Principles of Natural Selection
- Variation
- Differential Reproductive Success
- Heritability
The Principles of Natural Selection
The giraffe’s long neck is adaptive for eating tree leaves high off the ground
Observed Examples of Natural Selection
Directional selection
Normalizing selection
Balancing selection
Heredity:
Gregor Mendel’s Experiments
Dominant
The allele of a gene pair that is always phenotypically expressed in the heterozygous form.
Recessive
An allele phenotypically suppressed in the heterozygous form and expressed only in the homozygous form
Genotype
The total complement of inherited traits or genes of an organism
Phenotype
The observable physical appearance of an organism, which may or may not reflect its genotype or total genetic constitution.
Genes
Conveyors of Inherited Traits
Homozygous
Possessing two identical genes or alleles in corresponding locations on a pair of chromosomes
Heterozygous
Possessing differing genes or alleles in corresponding locations on a pair of chromosomes.
Mitosis
Split into identical cells from original cells (parents cells)
Meiosis
Makes you. Cells split into new cells.
Acclimatization
Impermanent physiological changes that people make when they encounter a new environment.
Influence of the Cultural Environment
Culture allows humans to modify their environments, and such modifications may lessen the likelihood of genetic adaptations and physiological acclimatizations.
Bergmann’s rule
The slenderer populations of a species inhabit the warmer parts of its geographic range, and the more robust populations inhabit the cooler areas.
Allen’s rule
Protruding body parts(e.g., limbs) are relatively shorter in the cooler areas of a species’ range than in the warmer areas. Research comparing human populations tends to supportAllen’s rule.
Other forms of physical variation
Skin Color (Gloger's RuleClinal Variation) Adaptation to High Altitude Susceptibility to Infectious Diseases Sickle-Cell Anemia Lactase Deficiency
Height
Differences in human size seem to be the result of both adaptations and acclimatizations, with both of these, in turn, affected by cultural factors such as nutrition and stress.
Cloning
The exact reproduction of an individual from cellular tissue
Genetic engineering
The substitution of some genes for others—is increasingly practiced in nonhuman organisms
