evolutionevolutionevolutionevolution. questions to ponder true/false 1. you can web your hands if...
TRANSCRIPT
Questions to Ponder Questions to Ponder TRUE/FALSETRUE/FALSE
1.1. You can web your hands if you try. You can web your hands if you try. 2.2. You can acquire traits in your lifetime that will You can acquire traits in your lifetime that will
help you survive.help you survive.3.3. All organisms have the same chance for All organisms have the same chance for
survival. survival. 4.4. All organisms need the same favorable trait. All organisms need the same favorable trait. 5.5. Evolution of most organisms occurs during Evolution of most organisms occurs during
their lifetime. their lifetime.
THEORIES OF EVOLUTION: THEORIES OF EVOLUTION: LAMARCK VS. DARWIN LAMARCK VS. DARWIN
Lamarck (1744-1829)Lamarck (1744-1829) Darwin (1809-1882)Darwin (1809-1882)
LAMARCK’S THEORIESLAMARCK’S THEORIES Jean Baptiste de Lamarck (1744-1829)Jean Baptiste de Lamarck (1744-1829)
TheoryTheory: Similar species descend from a : Similar species descend from a common ancestor (evident in fossil record)common ancestor (evident in fossil record)
To Explain how species change he hypothesized:To Explain how species change he hypothesized: Acquired traitAcquired trait: a trait NOT determined by : a trait NOT determined by
genes, it arises during an organisms lifetime as genes, it arises during an organisms lifetime as a result of behavior and can be passed onto a result of behavior and can be passed onto offspring offspring
Acquired TraitAcquired Trait Example: giraffes Example: giraffes
evolved their long evolved their long necks by each necks by each generation generation stretching further stretching further to get leaves in to get leaves in trees and that this trees and that this change in body change in body shape was then shape was then inherited. inherited.
CHARLES DARWIN (1809-1882)CHARLES DARWIN (1809-1882)
Darwin was recommended to be a Darwin was recommended to be a naturalist on the ship H.M.S. Beagle naturalist on the ship H.M.S. Beagle
Sailed around the World in Beagle for five Sailed around the World in Beagle for five years-collected specimens and recorded years-collected specimens and recorded lots of data lots of data
Darwin reasoned that Earth is dynamic, Darwin reasoned that Earth is dynamic, constantly changing –earthquakes, constantly changing –earthquakes, volcanoes, mountain formation- volcanoes, mountain formation-
Changes are a long slow process-Changes are a long slow process-organisms must adapt to changes or ? organisms must adapt to changes or ?
Darwin’s TheoriesDarwin’s Theories
Descent with ModificationDescent with Modification Newer forms appearing in the fossil record are Newer forms appearing in the fossil record are
modified descendents of older species modified descendents of older species
All species had All species had descended from one or a few descended from one or a few original types of life original types of life
Modification by Natural SelectionModification by Natural Selection
Describes how evolution occurs!Describes how evolution occurs!
1.1. Living things face a constant Living things face a constant strugglestruggle for for existenceexistence
**organisms in nature produce more than **organisms in nature produce more than can survive**can survive**
2. Variation exists within populations: 2. Variation exists within populations: - mutation - mutation
- Crossing Over/Independent - Crossing Over/Independent
Assortment (make different gametes)Assortment (make different gametes)
- Sexual reproduction - Random - Sexual reproduction - Random fusionfusion
of two gametesof two gametes Through mutation three variations of neck length exist: Short, Medium and long necks.
**POPULATIONS
HAVE
VARIATIONS**
3. 3. Non-random Non-random SurvivalSurvival and Reproduction and Reproduction
-Individuals with traits best -Individuals with traits best suitedsuited to their to their environment (environment (favorable traitsfavorable traits) survive and ) survive and reproduce in high numbers reproduce in high numbers
** SOME VARIATIONS ARE FAVORABLE**** SOME VARIATIONS ARE FAVORABLE**
-Having a high number of favorable traits gives -Having a high number of favorable traits gives the organisms an the organisms an adaptive advantageadaptive advantage
The long neck giraffe has the “best advantage” and therefore reproduces more than the others
4. These favorable traits have to be heritable (able 4. These favorable traits have to be heritable (able to be passed down to offspring)to be passed down to offspring)
**SURVIVORS HAVE FAVORABLE TRAITS TO **SURVIVORS HAVE FAVORABLE TRAITS TO PASS TO OFFSPRING**PASS TO OFFSPRING**
- Fitness:- Fitness: organisms ability to survive and organisms ability to survive and pass pass on its geneson its genes
Long neck giraffes have baby long neck giraffes
5. 5. Adaption:Adaption: The number of organisms with The number of organisms with favorable traits increases favorable traits increases
Populations Populations geneticallygenetically change to become change to become more suited to the environmentmore suited to the environment
The entire population of giraffes now ALL have long necks
**POPULATIONS
CHANGE OVER
TIME**
Summary: Summary:
Natural selection is not an active process: Natural selection is not an active process: the environment “selects” the traits that the environment “selects” the traits that are favorable and those that are not are favorable and those that are not
If the environment changes, so must the ...If the environment changes, so must the ...
Outcomes of Natural SelectionOutcomes of Natural Selection
Most traits resemble bell curve for Most traits resemble bell curve for phenotypesphenotypes
Natural Selection can alter variation in a population in three ways:
Stabilizing Selection Stabilizing Selection
Favors individuals with the Favors individuals with the averageaverage phenotype of the trait (average form have phenotype of the trait (average form have the highest fitness)the highest fitness)
Directional SelectionDirectional Selection
Environmental conditions favor individuals Environmental conditions favor individuals of one of one extremeextreme phenotype phenotype
Disruptive Selection Disruptive Selection
Environmental conditions favor individuals Environmental conditions favor individuals of both of both extremesextremes of the phenotype. of the phenotype.
Can lead to creation of a new speciesCan lead to creation of a new species
SameStructureDifferentFunction
HomologousStructure
SameFunctionDifferentStructure
AnalogousStructure
ReducedFunction
ofbody part
VestigialStructure
similiarembryos
Similaramino acids
andproteins
similarDNA
Law ofSuperpositionNew layers on
top of old layers
incompleterecordof life
on Earth
Evidence of Evolution
SameStructureDifferentFunction
HomologousStructure
SameFunctionDifferentStructure
AnalogousStructure
ReducedFunction
ofbody part
VestigialStructure
ComparativeAnatomy
similiarembryos
Embryology
Similaramino acids
andproteins
similarDNA
MolecularBiology
Law ofSuperpositionNew layers on
top of old layers
incompleterecordof life
on Earth
FossilRecord
Evidence of Evolution
Evidence of EvolutionEvidence of EvolutionComparative AnatomyComparative Anatomy
Homologous Structures: same structure but Homologous Structures: same structure but different functiondifferent function
Evidence of EvolutionEvidence of EvolutionComparative AnatomyComparative Anatomy
Analogous StructureAnalogous Structure
- same function but same function but
different structuresdifferent structures
Evidence of EvolutionEvidence of EvolutionComparative AnatomyComparative Anatomy
Vestigial Structure - body part that is Vestigial Structure - body part that is reduced or has no usereduced or has no use
Patterns of Evolution Patterns of Evolution
Ways species change to adapt to their habitats:
o Coevolution
o Convergent Evolution
o Divergent Evolution
Patterns of Evolution Patterns of Evolution
Coevolution:Coevolution: Two or more species change Two or more species change together!together!
Examples:Examples:
1)1) Predator/PreyPredator/Prey
2)2) Plant and pollinatorPlant and pollinator
Patterns of Evolution Patterns of Evolution Convergent: Convergent: Two dissimilar species Two dissimilar species
becoming similarbecoming similar
Environment selects for similar Environment selects for similar phenotype (but ancestors were phenotype (but ancestors were different)different)