Patterns In Evolution

Download Report

Transcript Patterns In Evolution

Patterns In Evolution
Two Major Patterns Observed
• Macroevolution: evolution of groups larger
than an individual species. Takes a long period
of time
Macro= looking at bigger sections
of evolution
The 6 Patterns that influence how
macroevolution occurs are…
1-Mass Extinctions 2-Adaptive Radiation
3-Convergent or Divergent Evolution
5-Punctuated Equilibrium
Mass Extinction
• Loss of complete huge number of species and
ecological systems
• Causes could be:
– large asteroid during the Cretaceous period l
throwing huge amonts of dust and vapor
altering global climate affects organisms…like
– Volcanic eruptions, continental shifts, changing
sea levels, other major environmental changes
Adaptive Radiation
• A single species or a small group of species
evolved into several different forms and live in
different ways
– Darwin’s Finches
Convergent Evolution
• Unrelated organisms come to
resemble each other
• This effect is due to different
organisms undergoing adaptive
radiation in different places BUT
in ecologically similar
• Face similar environmental
• Examples: streamlined bodies
and flippers of water organism (
shark, dolphin, seals, penguins)
Convergent Evolution
Divergent Evolution
• Because of different environments organisms
begin to look more and more different over
• Ex) Dog and Wolf
• Two species evolve in response to each other
due to ecological interactions
– Flowers and insects(Madagascar orchid and hawk
– Plants and plant eating insects: plants have
developed poisons to prevents plant eating
insects from feeding on them. Natural selection in
insect eating plant favored variants that could
alter, inactivate, or eliminate the poisons both
organisms change in response to each other
Macroevolution is also influenced
by… RATE
• Rate= how quickly the evolution occurs
Quick= Punctuated Equilibrium
Gradual= Gradualism
Punctuated Equilibrium
• Pattern of long, stable periods interrupted by
brief periods of rapid changes. Punctuated on
the right
When does this type of evolution
• Small populations become isolated from the
main part of the population .Population
changes quicker because genetic changes can
spread more quickly among fewer organism
• Small group of organisms migrate to a new
slow change in a population over a long period
of time
• Quick change in gene frequency within a
• Quicker then macroevolution.
• observed over short periods of
Examples: Antibiotic resistance,
Pesticide resistance
Antibiotic resistance
Bacteria can evolve quicker when they are
resistant to the antibiotic. This is because of
genetic shuffling due to their quick
reproduction rateswhich means more
chances for mutation (changes) less likely to
be killed by antibiotics if they have changed
their genes SO SMART!!
Microevolution example
• Imagine that you go to the mountaintop this year, sample these beetles,
and determine that 80% of the genes in the population are for green
coloration and 20% of them are for brown coloration. You go back the next
year, repeat the procedure, and find a new ratio: 60% green genes to 40%
brown genes.
• You have detected a micro evolutionary pattern: a change in gene
frequency. A change in gene frequency over time means that the
population has evolved.
What caused the microevolution?
Mutations in genes
Migration of organism
Genetic Drift of alleles
Natural Selection of the environment for a
given trait