How did the giraffe get its long neck?. More offspring are produced that can possibly survive. BUT...
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Transcript of How did the giraffe get its long neck?. More offspring are produced that can possibly survive. BUT...
How did the giraffe get its long neck?
More offspring are produced that can possibly survive.
BUT populations tend to remain stable
AND there are limited resources
Observation #1
SO the inference is:
There is a struggle for survival between individuals of a population and not all will survive
Aphaenogaster tipuna ants fighting over food
Organisms display a lot of variety in their characteristics
Much of this variety is inherited
OBSERVATION #2
Inference #2:
Those individuals whose inherited traits best fit them to their particular environment will leave more offspring
Inference #3:
This unequal ability of individuals to survive and reproduce will cause a gradual change in the population
Favorable characteristics will accumulate in the population over time
Individuals DO NOT EVOLVE. Populations evolve
Evolution is not caused by a NEED of an individual.
Surviving does not contribute to evolution alone. There also has to be reproduction
Acquired characteristics are not passed down to the next generation.
Adaptations depend on the environment
Fossils provide evidence of the change of life throughout time
Comparative Anatomy
Homologous structures: indicators of a common ancestor
Anatomical
Show divergent evolution
vestigial structures
Homologous structures with no or little function in organism
Embryological homologies
Molecular
Homologies
Compare DNA sequences or proteins (amino acid sequences)
The more differences the longer ago the two species diverged from a common ancestor
Generation to generation change in the frequencies of alleles in the
gene pool
Genetic Drift: changes in allele frequencies due to chance
Causes:natural selection
Gene flow immigration or emigration of individuals (and their genes)Mutation introduces new alleles
Examples of Genetic DriftBottleneck effect
Natural disaster wipes out a portion of a population
Fig. 13-11a-1
Originalpopulation
Fig. 13-11a-2
Originalpopulation
Bottleneckingevent
Fig. 13-11a-3
Originalpopulation
Bottleneckingevent
Survivingpopulation
Example #2Relatively few individuals start a new population in isolation
founder effect
A population that is not evolving is in equilibriumHardy-Weinberg Equilibrium
p=frequency of the dominant alleleq=frequency of the recessive allelep+q=1
p2 +2pq +q2=1
p2 = frequency of homozygous dominants2pq= frequency of heterozygotesq2= frequency of homozygous recessives
Conditions required for a population to maintain Hardy-Weinberg equilibrium
1. Large population2. Random mating3. No natural selection4. No mutation5. No gene flow
Analogous structuresEvolved independently and don’t indicate close relationships
A) Divergent evolution results in homologous structures
B) Convergent evolution results in analogous structures
Population or group of populations that have the potential to interbreed with each other in nature and produce viable offspring
Key idea: reproductive isolation
Fig. 14-3
Fig. 14-3a
Habitat isolation
Fig. 14-3b
Behavioral Isolation
Behavioral Isolation
Fig. 14-3c
Mechanical Isolation
Fig. 14-3d
Gametic Isolation
Fig. 14-3e
Postzygotic BarriersHybrids do not develop into
fertile adults
National Geographichttp://www.youtube.com/watch?v=1zOWYj59BXI
Speciation is the formation of a new species
Often it comes about because of some kind of geographic barrier
Adaptive radiation is a type of speciation
One population evolves into several different species, each with different adaptive characteristics
Phylogenetic trees
Mediumground finch
Cactusground finch
Smalltree finch
Largeground finch
Smallground finch
Large cactusground finch
Sharp-beakedground finch
Vegetarianfinch
Seedeaters
Ground finches
Cactus flowereaters
Budeaters
Tree finches
Insecteaters
Mediumtree finch
Largetree finch
Mangrovefinch
Woodpeckerfinch
Greenwarbler finch
Warbler finches
Which finch is most closely related t the Green warbler finch?
Is the medium ground finch more closely related to the small ground finch or to the large ground finch?
Big eyes
3 toes Loss of tail
• Beastie Activity
Fig. 15-16aa
Igu
ana
TAXA
Longgestation
Du
ck-b
illed
pla
typ
us
Kan
gar
oo
Bea
ver
CH
AR
AC
TE
RS
Character Table
0 00 1
0 10 1Gestation
Hair, mammaryglands 0 11 1
Fig. 15-16ab
Long gestation
Gestation
Hair, mammary glands
Iguana
Duck-billedplatypus
Kangaroo
Beaver
Phylogenetic Tree
Big eyes
3 toes Loss of tail
Figure 15.12A
Pleistocene
Pliocene
Mio
ce
ne
Oli
go
ce
ne
Brown bearPolarbear
Asiaticblack bear
Americanblack bear
Sunbear
Slothbear
Spectacledbear
Giantpanda
RaccoonLesserpanda
Ursidae
Procyonidae
Common ancestralcarnivorans
• For several decades, scientists have classified life into five kingdoms
Classification
Figure 15.14A
MONERA PROTISTA PLANTAE FUNGI ANIMALIA
Earliestorganisms
• This system recognizes two basically distinctive groups of prokaryotes
– The domain Bacteria– The domain Archaea
• A third domain, the Eukarya, includes all kingdoms of eukaryotes
Figure 15.14B
BACTERIA ARCHAEA EUKARYA
Earliestorganisms
A newer system is the 3 Domain system
• Organisms are grouped into progressively larger categories (taxons)
Table 15.10
CLASSIFICATION(TAXONOMY)
DOMAIN KINGDOM PHYLUM CLASS ORDER FAMILY GENUS SPECIES (SMALLEST GROUP)
NAMING OF ORGANISMS
BINOMIAL NOMENCLATUREEX: Homo sapiens
Pan troglodytes (chimpanzee)
FIRST NAME IS GENUS NAMESECOND NAME IS SPECIES NAME
5 KINGDOMS
1) MONERA
2) PROTISTA
3) FUNGI
4) PLANTAE
5) ANIMALIA
http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/Classification-Plants-Other-Organisms.topicArticleId-23791,articleId-23659.html