chapter11 Flashcards
There still have macroevolution in modern human population
True
Macroevolution
Changes. In genes frequency influence human genetic and phenotypic variation
The difference between nature selection and others
Natural selection is about change allele frequencies relative to specific environment factor
But mutation,gene flow, genetic drift– infuence what alleles present in population
What happen when environment change
The selection pressure change Nature of the selection might change
The other called about allele frequencies shift
Adaptation
What is “height and weight “
Continues trait , it can shift
What is about Gaussian distribution
Selections for either tail
Bergmann’s rule
Warm areas, slender body type ( smaller - sized ) of its geographical range ;cooler areas more robust body type
Allen’s rule
Warmer area, protruding body parts( limbs ) longer; cooler area, shorter
The principle of Bergmann’s rule and allen’s rule
More/ less surface area to body mass= dissipation/ retention of body heat
The direction of natural selection is influenced by characteristics of the local environment
But not all change occurs as a result of natural selection
Environment influences also associat with ?
Genetic potential complex trait
Directional selection
Increasing the frequency of a trait ( positive favored or adaptive)
Normalizing selection
Removes harmful genes that arose by mutation Average value doesn’t change removes the extreme (against tail
How deal with normalizing selection
Medical interventions & improvements ( NICU,CS)= improved survival Relaxed selection
Relaxed selection
Is a selective phenomena. , selective pressure are either elimated or dramatically reduce
The difference of balancing selection and the other two
It is at genetic level
The feature balancing selection
Occurs when a heterozygous 杂合子（Aa) combination of alleles is positively favorited even though a homozygous 纯合子（aa AA) combination is disfavored
