Final Review Flashcards
3 mechanisms for microevolution
natural selection
genetic drift
gene flow
how can new genes arise
mutations gene duplications
point mutation
change in one base in a gene
effect of point mutations
result in change in protein
can be hidden from selection in recessive alleles
can sometimes be beneficial
five conditions for nonevolving populations(hardy weinberg)
no mutations random mating no natural selection large population sizes no gene flow
three major factors that alter allele frequencies and bring on evolutionary change
Natural selection
Genetic drift
Gene flow
genetic drift
describes how allele frequencies fluctuate unpredictably from one generation to the next
Genetic drift tends to reduce genetic variation through losses of alleles
founder effect
occurs when a few individuals become isolated from a larger population
effects of genetic drift
significant in small populations
can cause allele frequencies to change at random
can lead to a loss of genetic variation within populations
harmful alleles may become fixed
frequency dependent selection
the fitness of a phenotype declines if it becomes too common in the population
speciation
the origin of new species
microevolution
consists of changes in allele frequency in a population over time
macroevolution
refers to broad patterns of evolutionary change above the species level
temporal isolation
Species breed at different times of the day, seasons, or years.
behavioral isolation
Courtship rituals and other behaviors unique to a species
mechanical isolation
Morphological differences can prevent successful completion of mating
gametic isolation
Sperm of one species may not be able to fertilize eggs of another species
sympatric speciatin can take occur
Polyploidy
Sexual selection
Habitat differentiation
polyploidy
is the presence of extra sets of chromosomes due to accidents during meiosis
Far more common in plants than in animals
Polyploidy can produce new biological species in sympatry within a single generation
autopolyploid
is an individual with more than two chromosome sets, derived from a single species
allopolyploid
is a species with multiple sets of chromosomes derived from different species
result of hybrid zones
reinforcement
fusion
stability
Reinforcement (strengthening of reproductive barriers – hybrids cease to form)
Fusion (weakens reproductive barriers – 2 species fuse back together)
Stability ( continues hybrid production)
how life may have started on earth
Abiotic synthesis of small organic molecules
Joining of these small molecules into macromolecules
Packaging of molecules into protocells
Origin of self-replicating molecules
what is the fossil record in favor of
Existed for a long time
Were abundant and widespread
Had hard parts
tetrapods
mammals
gelogic record
Hadean, Archaean, Proterozoic, and Phanerozoic eons
phanerozoic era
last half billion years
Paleozoic, Mesozoic, and Cenozoic
stomatolites
oldest fossils, 3.5 billion years ago
where does O2 come from
from biological reactions
endosymbiont theory
a cell that lives within a host cell
serial endosymbiosis
supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events
Inner membranes are similar to plasma membranes of prokaryotes
Division and DNA structure is similar in these organelles and some prokaryotes
These organelles transcribe and translate their own DNA
Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes
cambrian explosion
refers to the sudden appearance of fossils resembling modern animal phyla in the Cambrian period (535 to 525 million years ago)
Fungi, plants, and animals began to colonize land
about 500 million years ago
rise and fall of groups depends on
speciation
extinction rates within the group
pangea
about 250 million years ago
A deepening of ocean basins
A reduction in shallow water habitat
A colder and drier climate inland
continental drift
A continent’s climate can change as it moves north or south
Separation of land masses can lead to allopatric speciation
