Introduction to EVOLUTION Biology 11 1 How the

Introduction to EVOLUTION Biology 11 1

How the Turtle Got its Shell. . . 260 million old fossil shows how the turtle got its shell. . . basically back bones fused together. 2

T. Rex was a Chicken? ? ? In 2003, scientists discovered preserved soft tissue in a 68 million-year old thighbone of a T. Rex. In 2007, this tissue was tested twice (independently) and indicated that the T. Rex is likely related to the present day chicken. 3

EVOLUTION 1. PRESCRIBED LEARNING OUTCOMES and VOCABULARY 2. VIDEO: The Origin of Species: The Making of a Theory 3. TEXTBOOK PGS : Chapter 14 pg 290 -317 4

Warm Up Activity On a separate sheet of paper, write down some responses to the following questions: 1. What is evolution? What do you already know about it? 2. Where did all the different types of plants and animals on Earth get here? How did humans appear on Earth? 3. Are we the most advanced, perfected, important form of life on earth? 5

A Brief History of the Theory of Evolution Creationalism: the religious belief that all life was made by a supernatural being and that species have not changed Jean-Baptiste Lamarck- In early 1800’s, proposed animals evolve through inheritance of acquired characteristics (not true!) 6

A Brief History of the Theory of Evolution Charles Darwin (with help from Alfred Russel Wallace) first presented his theory of evolution through Natural Selection in 1859. Voyage of the BEAGLE 7

A Brief History of the Theory of Evolution Darwin suggests there was variation in a population and that those that are best suited to the environment survive and pass on their traits to their offspring 8

Evidence for Evolution 1. Direct evidence in stone (=fossils) -generally, deeper specimens are more ancient ACTIVITY: The Evolution of Barbellus Cut and Paste 2. Geological time scale (=rock layers) -use radioactive carbon dating to determine age of the rock (and fossils within it) 9

Evidence for Evolution 3. Living organisms have similarities in early development -the embryos of many different species look similar 4. Living organisms have similarities in Body Structure -includes homologous structures (same ancestor, different function, e. g. dog limbs, human arms, fish fins) 10

Evidence for Evolution 5. Similarities in chemical compounds (DNA, proteins, amino acids) ACTIVITY: Evidence for Evolution Worksheet 11

Key Aspects Proposed by Darwin… 1. There is variation of TRAITS within a population e. g. eye colour, height, ability to run fast, etc This is called a BELL CURVE Variation of a trait within a population may be large (wide curve) or small (skinny curve) 12

Key Aspects Proposed by Darwin… 2. Birthrates are high so populations should GROW (like, out of control!) We only see this happening with humans…but why? 13

Key Aspects Proposed by Darwin… 3. A struggle for existence ensures population controls -competition between individuals (NICHES) • a NICHE is the combination of an organism’s “profession” and the place in which it lives • no two species can occupy the same niche in the same location for a long period of time They will compete for food and home! The more efficient species will survive and reproduce; the other will leave or die 14

Key Aspects Proposed by Darwin… There is also struggle through. . . -predators -environment stresses 15

Key Aspects Proposed by Darwin… What do we conclude is happening? NATURAL SELECTION= the process that results in the most FIT organisms producing offspring This is similar to ARTIFICIAL SELECTION (human breeding of plants and animals) but without human influence and taking a longer time 16

Natural Selection Survival of the fittest- only those organisms best adapted to an environment will survive, produce offspring, and pass on their genes. Well-suited traits= survive! (genes passed on) Poorly-suited traits= death! (genes not passed on) 17

An Example of Natural Selection The Peppered Moth the trait is moth colour (controlled by genes/DNA) the selective pressure is predators the trait varies within the population and changes over time nonpolluted forest, lots of lichen polluted forest, lots of soot but no lichen Activity: Peppered Moth Simulation Game 18

The Events of Natural Selection STEPS: 1. Variety exists in a population (favourable and unfavourable) 2. A selective pressure acts on the population -e. g. limited types of food available to birds selects for a particular type of bird beak (strong for nuts, sharp for insects etc) 3. A portion of the population is removed due to the action of the selective pressure. These animals were less fit and die. 19

The Events of Natural Selection 4. Survivors pass on favorable traits to their offspring. -traits are determined by proteins, which are controlled by genes (DNA) -through reproduction, you pass on your genes to your offspring 5. The distribution of favourable traits shift in the population (more of the offspring have the trait) 6. The selective pressure acts (with similar results) on the population for many generations Ha ha, you can’t hurt me now!!! I’m RESISTANT 20

Types of Natural Selection There are 3 types: 1) Directional Selection -one extreme trait is selected against- this is a less common trait found on the edge of the curve -population shifts to the right or to the left (depends on which trait is being selected against) -the average changes e. g. giraffe neck length; selection for taller necks resulted in longer necks becoming more common 21

Types of Natural Selection 2) Stabilizing Selection -two extreme traits are selected against- these are less common traits found on both edges of the curve -population does not shift, but has less variety of traits -the average does not change, but the FREQUENCY of the average trait has increased e. g. flower colour; selection against white and red flowers resulted in pink flowers becoming more common; red and white flowers become less common 22

Types of Natural Selection 3) Disruptive Selection -the two extreme traits are favoured- the most common trait is selected against -population splits in two; this may over time lead to two separate species e. g. bird colour; selection against grey birds resulted in white and black birds becoming more common; grey birds become less common 23

In Summary: Activity: Worksheets (X 2) on Types of Natural Selection 24

A New Species Evolves! Species= a group of organisms that can breed with one another and produce fertile offspring in a natural environment Speciation= the process of new species evolving from an old one **New species usually form only when POPULATIONS are isolated or separated** Population- groups of organisms of the same species whose members can breed with one another; more than 5 individuals 25

Isolation of a Population Pre-zygotic Isolation 1) Geographical barriers- rivers, mountains, roads 2) Behavioural differences- Courtship behaviours or fertile periods Eww. . Budgie- budgie Budgie lovebird 26

Isolation of a Population Cont’d 3) Habitat Preference- live in different places in an area e. g. meadow vs. wooded areas 4) Mating Seasons Differences e. g. frogs in Texas breed 2 -3 months earlier than frogs elsewhere 5) Body Size or structural differencese. g a tiny poodle will not mate with a large husky 27

Isolation of a Population Cont’d Post-zygotic Isolation: 1) Sterile offspring- e. g. ) a donkey and a horse give rise to a sterile offspring 2) Offspring die after being born 3) Aborted during pregnancy 28

A New Species Evolves! If two populations are reproductively isolated, natural selection is different for each group. results in each population become better adapted to different environments. over time, their separate gene pools gradually become more dissimilar, leading to two separate species. 29

Another Example of Speciation: Darwin’s Finches Found on various nearby islands; beaks adapted to the type of food they eat 30

An Example of Speciation: Darwin’s 13 Finches 1. Founding Fathers and Mothers- first explorers to arrive at Island A 2. Separation of Populations- birds fly from Island A to Island B (ocean is a geographical barrier) 3. Changes in the Gene Pool- populations on ach island became adapted to the needs of their environments (i. e. beak size) 4. Reproductive Isolation-difference in beak size makes species A look unworthy to mate with to species B. They will no longer interbreed; this leads to separate species 5. Sharing the Same Island- leads to coexistence (if they live in different niches), extinction (if they live in the same niche), or further evolution are possible ACTIVITY: Gizmo: Rainfall and Bird Beaks (Metric) 31

What Darwin didn’t know… Why do we have such variation? different combinations of GENES passed on through sexual reproduction changed by MUTATIONS in your DNA ACTIVITY: Ph. ET Natural Selection http: //phet. colorado. edu/en/simulation/natural-selection You have inherited your traits from your parents! Thanks dad and especially mom! Video: http: //www. youtube. com/watch? v=os. Wu. Wjbe. O-Y 32

Thanks DNA! 33

Structure of DNA • Deoxyribonucleic acid is made up of many nucleotide subunits. • a nucleotide consists of a sugarphosphate backbone and a nitrogenous base • Bases: Adenine, Guanine, Thymine or Cytosine • Complimentary base pairing is A-T and C-G only! • Bases bonded by weak H-bonds ACTIVITY: Modelling DNA Cut and Paste 34

Protein Synthesis DNA makes proteins physical traits Involves 2 steps: 1. Transcription -DNA unzips, a copy of RNA is made in the nucleus 2. Translation -RNA leaves the nucleus and is “read” by a ribosome. TRNA matches the codons on RNA and brings amino acids. A chain of amino acids is formed = protein. Protein Synthesis Animation: http: //www. learnerstv. com/animation/biology/Proteinsynthesis. swf ACTIVITY: Protein Synthesis Comic 35

The Role of DNA & Mutations Speciation involves changes in PHENOTYPE (physical characteristics) that arise due to changes in GENOTYPE (genetic code, or DNA) Changes in DNA are called MUTATIONS Most (99%) mutations are HARMFUL and lead to DEATH! Some mutations are beneficial and improve the FITNESS of an individual. This potentially allows for more offspring, which will carry the mutation/new phenotype. 36

The Role of DNA & Mutations Fast Rabbit Escapes! Slow Rabbit Does Not Escape 37

The Role of DNA & Mutations ACTIVITY: Identify the Mutation Worksheet and Mechanisms of Evolution W/S 38

Mating Across Species An aside: some cross-species mating can occur but this is VERY, VERY rare!! Horse + zebra = zorse Shark + horse. . just kidding here! Lion + tiger = liger 39

Types of Speciation 1. Divergent Evolution (also known as Adaptive Radiation) -one species gives rise to many species that live in different niches -HOMOLOGOUS STRUCTURES (same ancestor but not necessarily same function)are evidence divergent evolution 40

Types of Speciation 2. Convergent Evolution -when two different organism produce species that are similar in appearance and behaviour -ANALOGOUS STRUCTURES (have same function but no common ancestor) are seen in convergent evolution 41

Types of Speciation 3. Parallel Evolution -when two different species evolve independently of one another- maintaining the same level of similarity -the two species usually do not live in the same niche 42

Parallel Evolution Example 43

VESTIGIAL STRUCTURES These are body structures that no longer serve its original purpose Examples: Whales have remnant “legs” Video: Whale Evolution http: //www. youtube. com/watch? v=8 cn 0 kf 8 mh. S 4 44

Shaping the Evolutionary Theory Hardy and Weinburg developed a mathematical model for evolution. They found that evolution will not occur in a population unless ALLELIC FREQUENCIES are acted apon = HARDY-WEINBURNG PRINCIPLE ALLELE= genetic trait; an alternative form of a characteristic that can be inherited e. g. Blue eyes, brown eyes, green eyes ALLELIC FREQUENCY= percentage of alleles in a population 45

Shaping the Evolutionary Theory A non-changing population (no change in allelic frequency) is said to be in GENETIC EQUILIBRIUM Five conditions for H-W Principle to work: 1. No genetic drift Of course, these 2. No gene flow happen in the real 3. No mutations world, so this model is not perfect 4. No selective mating 5. No natural selection Activity: Chapter 15 -2 - Mechanisms of Evolution Part I fitb 46

Rate of Speciation There are 2 models: the gradual change model and the punctuated equilibrium model of evolution 1. Gradual Change Model -occurs SLOWLY -consistent levels of change over time 47

Rate of Speciation 2. Punctuated Equilibrium Model -sudden big change followed by periods of little to no change Activity: Chp 15. 2 Mechanisms of Evolution Part II Read & fitb w/s 48

Other Agents of Evolutionary Change Natural selection and mutation are NOT the only way speciation occurs! Other agents of evolutionary change: 1. Genetic drift 2. Gene flow 3. Non-random mating 49

Other Agents of Evolutionary Change 1. Genetic drift (aka allelic drift) -is the change in frequency of a gene variant (ALLELE) due to RANDOM SAMPLING/CHANCE (e. g. fire, avalanche, etc) 50

Other Agents of Evolutionary Change 2. Gene flow (aka migration) -is the transfer of alleles or genes from one population to another. 51

Other Agents of Evolutionary Change 3. Non-random mating- humans use non-radom mating on plants and animals (selective breeding) 52

In Summary Simpson’s evolution video 53