Chapter 21: The Evidence for Evolution Flashcards
What is selection?
Process which some organisms leave remaining offspring than others.
Dependent on their phenotype and behaviour.
Inheritable traits of certain individuals are passed on in greater proportions to succeeding gen.
What are the five agents of evolutionary change?
Nonrandom mating Gene flow Genetic drift Mutation Selection
Nonrandom mating
Process where individuals possessing particular genotypes tend to couple with another more commonly rather than on random occasions.
Think: nonrandom - not random, i.e. tend to couple more often
Genetic drift
Certain alleles changing at random
Frequencies of certain alleles undergo drastic change randomly
Gene flow
Movement of alleles from one population to another
Powerful agent of change
Mutation
Permanent change in nucleotide sequence of DNA of a cell
E.g. in gene position, gene loss or duplication, insertion of foreign sequences.
What is the ultimate source of genetic variation, consequently making evolution possible.
Individual mutations rarely occur.
Mutation.
‘Absolute Dating’
Radioactive decay
Agent of selection
Not always easily identified
Early human embryos had pharyngeal pouches:
Indicates that one of our earliest ancestors was an aquatic species
Biogeographical studies show that species that live in close proximity
are not always closely related.
Domestication is a form of artificial selection that has resulted in ______selection for some traits
Answer: Unintentional
Horses originated:
55 MYA
_______ is the study of geographic distribution of species, reveals that different geographical areas sometimes exhibit groups of plants/animals with strikingly similar appearance, although may be distantly related
Biogeography
Marsupials & placentals demonstrate _______
convergence.
