Evolution

Lamarck’s Theory of Acquired Inheritance (early 1800s) Jean Baptiste Lamarck Observed fossil records and the current diversity of life Suggested that organisms evolved by the process of adaptation Traits gained during a lifetime could then be passed on to the next generation

More offspring are produced that can possibly survive. BUT populations tend to remain stable AND there are limited resources Observation #1 Charles Darwin

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 that 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

Artificial selection

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

Evidence of Evolution Fossil Record Biogeography Comparative anatomy Comparative embryology Molecular Biology

Evidence: Fossil Record Fossils –preserved remnants or impressions left by organisms that lived in the past. –often found in sedimentary rocks.

Fossil Formation 1.Dead animal sinks. Tissue begins to decay 2.Carcass covered with sediment. Lower layers turn to rock. 3.Rock is folded. 4.Fossil is exposed at the surface.

The fossil record Is the ordered sequence of fossils as they appear in rock layers. Reveals the appearance of organisms in a historical sequence. Fits with other evidence of evolution.

Generally less complex forms of life are found in oldest rocks. The fossil record

Evidence: Biogeography The geographic distribution of species Darwin noted that Galápagos animals –Resembled species of the South American mainland more than animals on similar but distant islands

Evidence: Comparative Anatomy Comparison of body structures between different species –Similarities give signs of common descent/common ancestor Homologous structures—features that have similar structure but may have different functions

Evidence: Comparative Anatomy Vestigial structures—Small body structures that may have been functional in the ancestors of a species, but have no or limited function at the present time

vestigial structures

Evidence: Comparative embryology Different organisms go through similar embryonic stages All vertebrates have an embryonic stage in which gill pouches and post-anal tail—evidence of a common ancestor

Molecular Biology Study of molecular basis of genes Universality of genetic code Conservation of amino acid sequences in proteins such as hemoglobin/cytochrome C

Figure 13.13

For each example below, identify the type of evidence of evolution 1.Cats and humans both have muscles for moving their ears 2. 3.The start codon places methionine at the first amino acid position for virtually all proteins 4. Over the past 47 million years the location of the nostrils are seen to have shifted posteriorly in relatives to the modern day dolphin

Generation to generation change in the frequencies of alleles in the gene pool Causes: Natural selection Genetic drift Gene flow Mutation

Natural selection

Genetic Drift: changes in allele frequencies due to chance Ex #1: Natural disaster wipes out a portion of a population

Fig a-3 Original population Bottlenecking event Surviving population

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

Gene flow immigration or emigration of individuals (and their genes) Population APopulation B

Mutation introduces new alleles

A population that is not evolving is in equilibrium Hardy-Weinberg Equilibrium mathematically describes these populations 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

There are 100 students in a class. Ninety-six did well in the course whereas four blew it totally and received a grade of E. In the highly unlikely event that these traits are genetic rather than environmental, if these traits involve dominant and recessive alleles, and if the four (4%) represent the frequency of the homozygous recessive condition, calculate the following: The frequency of the recessive allele. The frequency of the dominant allele. The frequency of heterozygous individuals.

Within a population of butterflies, the color brown (B) is dominant over the color white (b). And, 40% of all butterflies are white. Given this informationm calculate the following: The percentage of butterflies in the population that are heterozygous. The frequency of homozygous dominant individuals.

You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following: The frequency of the "aa" genotype. The frequency of the "a" allele. The frequency of the "A" allele. The frequencies of the genotypes "AA" and "Aa."

Comparative Anatomy

Homologous structures: indicators of a common ancestor Anatomical Show divergent evolution

A) Divergent evolution  results in homologous structures B) Convergent evolution  results in analogous structures

Analogous structures Evolved independently and don’t indicate close relationships

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. 14-3a Habitat isolation

Fig. 14-3b Behavioral Isolation

Fig. 14-3c Mechanical Isolation

Fig. 14-3d Gametic Isolation

Fig. 14-3e

National Geographic v=1zOWYj59BXI v=1zOWYj59BXI

Formation of new species -sometimes from geographic isolation Speciation

Parent species 2n = 6 Tetraploid cells 4n = 12 Diploid gametes 2n = 6 2 Viable, fertile tetraploid species 4n = 12 Self- fertilization 3 Speciation without geographic isolation Polyploidy  occurs in plants

Species A 2n = 4 Gamete n = Species B 2n = 6 Gamete n = 3 Sterile hybrid n = 5 Chromosomes not homologous (cannot pair) Viable, fertile hybrid species 2n = 10 3 Formation of hybrid that reproduces asexually and later (through errors in cell divisions) becomes fertile is common in plants

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

feathers

Beastie Activity

Big eyes 3 toestail

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

–Earth formed 4.6 billion years ago –Oldest fossils are 3.5 billion years old Photosynthetic bacteria in stromatolites –Heterotroph hypothesis –first living things (heterotrophs) are thought to be simpler and arose much earlier –Heterotrophs have much simpler metabolism, occurred before autotrophs Copyright © 2009 Pearson Education, Inc. EARLY LIFE

Chemical conditions Physical conditions Abiotic synthesis of monomers Formation of polymers Packaging of polymers into protobiontsprotobionts Self-replication Stage 1 Stage 2 Stage 3 Stage 4 Copyright © 2009 Pearson Education, Inc. Possible evolution of chemicals that could result in first cells

Possible composition of Earth’s early atmosphere –H 2 O vapor –N2–N2 –CO 2, CH 4, NH 3, –H 2, and H 2 S Energy sources –Lightning, volcanoes, UV radiation

Copyright © 2009 Pearson Education, Inc. Stage 1: Abiotic synthesis of monomers –Organic molecules were produced in the lab using molecules and energy sources thought to be on primitive earth

Copyright © 2009 Pearson Education, Inc. Stage 2: The formation of polymers –Monomers could have combined to form organic polymers –Same energy sources

Copyright © 2009 Pearson Education, Inc. Stage 3: Packaging of polymers into protobionts –Polymers could have aggregated into complex, organized, cell-like structures

Monomers Formation of short RNA polymers: simple “genes” 1 Assembly of a complementary RNA chain, the first step in replication of the original “gene” 2 protocells –Stage 4: Self-replication –RNA may have served both as the first genetic material and as the first enzymes

First organisms were prokaryotic eukaryotic organisms evolved later

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