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