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Population Genetics and evolution (Speciation (Divergent Speciation…
Population Genetics and evolution
Population Genetics
deals with the abundance of different alleles within a population and the manner in which a particular allele increase or decreases over time
Factors that Cause the Gene Pool to Change
Muatation
Accidents
Natural Selection
Factors that Are Not Part of Natural Selection
Purpose, Intention, Planning, or Voluntary Decision Making
Speciation
Natural Selection has caused a new species to evolve.
Phyletic Speciation
one species gradually becomes changed that it must be considered a new species
Divergent Speciation
some populations of a species evolve into a new, second species while other populations either continue relatively unchanged as the original , parental species or evolve into new third species.
Phyletic Speciation
Gene Flow
movement of alleles physically through space
Pollen Transfer
Seed Dispersal
Vegetative Propagation
Divergent Speciation
Reproductively Isolated
if alleles that arise in one part of the range do not reach individuals in another part
Abiological Reproductive Barriers
any physical, nonliving feature that prevents two populations from exchanging genes
Allopatric or Geographic Speciation
the original species is physically divided into two or more populations that cannot interbreed
Biological Reproductive Barriers
as biological phenomenon that prevents successful gene flow
Sympatric Speciation
when two groups become reproductively isolated even though they grow together
Prezygotic Isolation Mechanisms
act even before a zygote is formed
Hybrid Sterility
two populations occasionally interbreed or are artificially cross-pollinated and produce viable seed.
Postzygotic Internal Isolation Barriers
two subpopulations must be considered separate species
Hybrid Inviability
the zygote or embryo dies early in development
Adaptive Radiation
special case of divergent evolution
species rapidly diverges into many new species over an extremely short time
Founder Individual(s)
first
Genetic Drift
short evolution
heterozygous island
Convergent Evolution
two may evolve to the point that they resemble each other strongly
Evolution and the Origin of Life
Chemosynthesis
attempts to model the origin of life using only known chemical and physical processes, rejecting all traces of divine intervention
Conditions of Earth Before the Origin of Life
Chemicals present in the Atmosphere
Second Atmosphere
produced by release of gases from the rock matrix composing Earth
from heavy bombardment by meteorites.
Reducing Atmosphere
lack of molecular oxygen and the presence of power reducing agents
Oxygen
Oxidizing Atmosphere
the atmosphere today
derived from the early second atmosphere
addition of oxygen from photosynthesis
