Macroevolution/Microevolution
Macroevolution- One genus or familyfamily evolves into another….due to largelarge scale changes that take place over longlong periods of time.
Microevolution- SmallSmall scale changes within a species to produce new varieties or speciesspecies in a relatively shortshort amount of time.
Macroevolution/Microevolution
Both involve changes in alleleallele frequencies in genegene pools
The differencedifference is largely one of approach approach and scalescale
Each offers offers different insightsinsights into the evolutionevolution process
Macroevolution/MicroevolutionMacroevolution/Microevolution
Macroevolution1. Large-scale changes in gene
frequencies
2. Occurs over a longer longer (geological) time period time period
3. Occurs at or above the level level of speciesof species in separatedseparated gene pools
4. Consists of extendedextended
microevolutionmicroevolution
Microevolution1. Small-scaleSmall-scale changes in
gene frequencies
2. Occurs over a few few generationsgenerations
3. Occurs within a specieswithin a species or population in samesame gene pool
4. Refers to smallersmaller
evolutionaryevolutionary changes
Macroevolution/MicroevolutionMacroevolution/Microevolution
Macroevolution5. Has notnot been
directly observedobserved
6. Evidence based on
remnants remnants of the past past
7. Example: Birds from reptiles
Microevolution5. ObservableObservable
6. Evidence produced
by experimentationexperimentation
7. Example: Bacterial
resistance to
antibiotics
Dog Variability When bred for certain traits, dogs become different and distinctive. This is a common example of microevolution—changes in size, shape, and color—or minor genetic alterations. It is not macroevolution: an upward, beneficial increase in complexity.
Macroevolution/MicroevolutionMacroevolution/Microevolution
Patterns of MacroevolutionPatterns of Macroevolution
A. Mass Extinctions
B. Adaptive Radiation
C. Convergent Evolution
D. Coevolution
E. Gradualism
F. Punctuated Equilibrium
G. Developmental Genes
These are theories/models of evolution
Mass Extinctions ManyMany types of living things
became extinct at the same timeat the same time. Disrupted energy flowenergy flow caused
food websfood webs to collapsecollapse SpeciesSpecies disappeareddisappeared. Left habitatshabitats/niches openopen Resulted in burst of evolutionburst of evolution of
new species in new habitat
Mass ExtinctionsMass Extinctions
Possible causes– AsteroidsAsteroids hitting earth– VolcanicVolcanic eruptions– Continental driftdrift– Sea levelsSea levels changing
Adaptive Radiation (divergent evolution)
The evolution of an ancestral ancestral speciesspecies, into many diversemany diverse species, each adapted to a different habitatdifferent habitat
Many new speciesspecies diversify from a common ancestorcommon ancestor .
The new species livelive in differentdifferent ways thanthan the original original species did.
Adaptive RadiationAdaptive Radiation
Hawaiian honeycreepers
Variation in color and bill shape is related to their habitat and diet
Convergent EvolutionConvergent Evolution OppositeOpposite of divergent evolutiondivergent evolution (adaptive
radiation) UnrelatedUnrelated organismsorganisms independently evolve evolve
similaritiessimilarities when adapting to similarsimilar environments, or ecological nichesniches
Analogous structuresAnalogous structures are a result of this process
Example: penguin limb/whale flipperflipper/fish finfin The wings of insects, birds, and bats all serve
the same functionsame function and are similar in structuresimilar in structure, but each evolved independently independently
Convergent EvolutionConvergent Evolution
Similar body shapes and
structures have evolved in the
North American cacti...and in the
euphorbias in Southern Africa
Coevolution The mutual evolutionary influence between two
species When two species evolve in response to changes
in each other They are closely connected to one another by
ecological interactions (have a symbiotic relationship) including:– Predator/prey – Parasite/host – Plant/pollinator
Each party exerts selective pressures on the other, thereby affecting each others' evolution
CoevolutionCoevolution
Bumblebees and the flowers the they pollinate have co-evolved so that both have become dependent on each
other for survival.
CoevolutionCoevolution Praying Mantis simulates plant to protect itself
from predators and eats pests that are attracted to and feed on the plant, so it protects the plant.
Gradualism The evolution of new species by
gradual accumulation of small genetic changes over long periods of time
Emphasizing slow and steady change in an organism
Occurs at a slow but constant rate Over a short period of time it is hard to
notice
Punctuated Equilibrium Stable periods of no change (genetic
equilibrium) interrupted by rapid changes involving many different lines of descent
Opposite of gradualism Rapid events of branching speciation
Developmental GenesDevelopmental GenesDevelopment is a progressive
processThere are a variety of certain
developmental genes that regulate the timing of certain events
Developmental GenesHox genes – are master control
genesSome alter the position of an
organOthers alter
when things happen
Lamb born with seven legs
Hox GenesHox Genes
Determine body plansFunction in patterning the
body axisProvide the
identity of particular body regions
Hox Genes They are general purpose in the sense
that they are similar in many organisms
It doesn’t matter if it’s a mouse’s head or a fly’s head that is being built, the same gene directs the process
Hox Genes Most insects have two pairs of wings However, flies have one set of flying
wings and one set of small balancing wings
A single mutation in the gene will result in a fly with two complete sets of flying wings
This mutation results in an organ appearing in the wrong place.
Hox GenesHox Genes Hox Genes control
development and are common to most organisms.
Four groups of similar Hox Genes, shown in color, appear to control related regions of the human body and the fly.
Each box represents a single Hox Gene.
Illustration by Lydia Kibiuk, Copyright © 1994 Lydia Kibiuk.
Hox Genes Hox genes
determine the form, number, and evolution of repeating parts, such as the number and type of vertebrae in animals with backbones.
In the developing chick (left), the Hoxc-6 gene controls the pattern of the seven thoracic vertebrae (highlighted in purple), all of which develop ribs. In the garter snake (right), the region controlled by the Hoxc-6 gene (purple) is expanded dramatically forward to the head and rearward to the cloaca.
Patterns of Macroevolution
that are
can undergo can undergo can undergo can undergo can undergo
in underunderform inin
Species
Unrelated Related
Inter-relationships
Similar environments
Intense environmental
pressure
Smallpopulations
Different environments
Coevolution Convergent evolution Extinction
Punctuated equilibrium
Adaptive radiation
Flow ChartFlow Chart