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 tipunaAphaenogaster 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 Drift Bottleneck effect Natural disaster wipes out a portion of a population

Fig a-1 Original population

Fig a-2 Original population Bottlenecking event

Fig a-3 Original population Bottlenecking event Surviving population

Example #2 Relatively few individuals start a new population in isolation founder effect

A population that is not evolving is in equilibrium Hardy-Weinberg Equilibrium p=frequency of the dominant allele q=frequency of the recessive allele p+q=1 p 2 +2pq +q 2 =1 p 2 = frequency of homozygous dominants 2pq= frequency of heterozygotes q 2 = frequency of homozygous recessives

Conditions required for a population to maintain Hardy-Weinberg equilibrium 1.Large population 2.Random mating 3.No natural selection 4.No mutation 5.No gene flow

Analogous structures Evolved 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

Fig. 14-3c Mechanical Isolation

Fig. 14-3d Gametic Isolation

Fig. 14-3e Postzygotic Barriers Hybrids do not develop into fertile adults

National Geographic v=1zOWYj59BXI 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

Medium ground finch Cactus ground finch Small tree finch Large ground finch Small ground finch Large cactus ground finch Sharp-beaked ground finch Vegetarian finch Seed eaters Ground finches Cactus flower eaters Bud eaters Tree finches Insect eaters Medium tree finch Large tree finch Mangrove finch Woodpecker finch Green warbler 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 toesLoss of tail

Beastie Activity

Fig aa Iguana TAXA Long gestation Duck-billed platypus Kangaroo Beaver CHARACTERS Character Table Gestation Hair, mammary glands

Fig ab Long gestation Gestation Hair, mammary glands Iguana Duck-billed platypus Kangaroo Beaver Phylogenetic Tree

Big eyes 3 toesLoss of tail

Figure 15.12A Pleistocene Pliocene Miocene Oligocene Brown bear Polar bear Asiatic black bear American black bear Sun bear Sloth bear Spectacled bear Giant panda Raccoon Lesser panda Ursidae Procyonidae Common ancestral carnivorans

For several decades, scientists have classified life into five kingdoms Classification Figure 15.14A MONERAPROTISTAPLANTAEFUNGIANIMALIA Earliest organisms

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 BACTERIAARCHAEAEUKARYA Earliest organisms 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 NOMENCLATURE EX: Homo sapiens Pan troglodytes (chimpanzee) FIRST NAME IS GENUS NAME SECOND NAME IS SPECIES NAME

5 KINGDOMS 1) MONERA 2) PROTISTA 3) FUNGI 4) PLANTAE 5) ANIMALIA