Presentation on theme: " The change of populations of organisms over generations. The process by which all organisms have developed from older forms of life Old species."— Presentation transcript:
The change of populations of organisms over generations. The process by which all organisms have developed from older forms of life Old species go extinct (mass extinction) and new species arise. DAY 1
A group of organisms similar in structure and heredity capable of producing fertile offspring *breeding within the species…always exceptions to every rule… Examples?
Extra-terrestrial origin Creation/Divine force *Originate from non-living matter * Ch 21 IS THIS EVOLUTION? Once Life is here…evolution can occur- evolution is how life/species change and develop over time.
Abiotic synthesis of small, organic molecules (amino acids, nitrogenous bases) Miller/Urey 1953 ◦ “prebiotic soup”, no free O 2 + lightning + volcanoes = molecule ◦ Meteorites + Clay from volcanic ash Making macromolecules… proteins, nucleic acids Protocells/Protobionts/vesicles Origin of self replication inheritance …RNA or DNA? ◦ First genetic material- RNA, ribozymes-catalytic RNA (ribosomes); protein synthesis Anaerobic Heterotrophs > Chemautotrophs > Photoautotrophs (cyanobacteria) Splitting water*O 2 > Aerobes, Ozone layer > Endosymbiosis Exploring Life’s Origins
Endosymbiosis The road to all Eukaryotes: Endosymbiosis leads to- Membrane bound organelles Cytoskeleton Chromosomes/nucleus Cellular membranes, transport systems
Cyanobacteria Endosymbiosis Land Plants, Animals 200,000- Homo Sapiens (11:59:30) ~3.5 bya Stromatolites Oldest fossils- cyanobacteria
http://www.ucmp.berkeley.edu/precambrian/archean_hadean.php Shark Bay, Austrailia 2-3,000yo high salt content 100yrs to grow 5cm living fossils Cyanobacteria + sediment + Calcium Carbonate form limestone layers… Oldest fossils on Earth
Endosymbiosis *Eukaryotes or Prokaryotes? *Anaerobic or Aerobic? *Heterotrophs or Autotrophs? *Marine or Land? *Cyanobacteria- Importance? *Oldest Fossil? *Endosymbiotic Theory? *Why the diversity explosion? *Amphibians or Reptiles? *Warm or Cold Blooded? WHAT CAME FIRST?? +
FYI… Eon Eras Periods ◦ “firsts” ◦ Major changes in diversity Epochs Ages
Widespread and rapid decrease in the amount of life on earth. Sharp change in diversity and abundance. 98% of Documented Species are now Extinct.
How long will it take? What causes the changes? What evidence do scientists have to support the Theory of Evolution?
1. Fossils 2. Homologous Structures 3. Vestigial Structures 4. Embryonic Development 5. Biochemical Similarities: DNA Sequencing- Universal Code
Fossils are often found in sedimentary rock, which is formed from layers of silt and sand covering dead organisms. Types of Fossils??
In what ways is the fossil record considered biased?
Similar structure and anatomical position (but not necessarily the same function) in different organisms: “ICA” “ICA” = Indicates Common Ancestor Hand, Paw, Fin, Wing??
Same lineage, evolving apart to be more different. For example, bats and horses. Both share the same lineage as mammals, but the limb of the bat became wings while the horse developed hooves. Produces homologous structures
Similar Appearance and Function- does NOT indicate ICA Ex- Bird and Insect Wings Porpoise and Shark Fins Built on a different blueprint
The closer the DNA sequences of 2 organisms are, the more closely related they are. ◦ Humans and chimps have DNA that is 98.4% identical DNA and RNA are carriers of genetic information The genetic code is universal Some Metabolic pathways are conserved (same/similar) across all domains
ARISTOTLE~335 BC Species change over time, moving toward a “perfect state”. LAMARCK 1744-1829 FIRST to clearly state: Types of organisms changed over time because of natural phenomenon not divine force. New species were modified descendants of older species. DAY 2
“OUT”/ Discredited Ideas…. Theory of Need: a change in the environment produced a need for change in organisms 1. Use and Disuse If organs were used- they remained, if unused, they would disappear. “Use it or Lose It”….all inheritable changes 2. Inheritance of Acquired Characteristics Not determined by heredity; ‘acquired traits’ are acquired in ones lifetime in response to ones experience or behavior.
THEORY OF NATURAL SELECTION Organisms with traits more favorable to a particular environment are more likely to pass on those traits to their offspring. *Environment plays a key role. (HW Ch 18)
WHERE LAMARCK FAILED: INDIVIDUALS DO NOT EVOLVE, POPULATIONS DO
1856 Alfred Wallace 1858 Papers of Darwin & Wallace read 1859 Publishes his work
1. VARIATIONS exist in individuals within a species (caused by mutations/genetic recombination). Those with favorable variations have an advantage for survival. Live Longer > Produce more offspring > Genes passed on 2. OVERPRODUCTION of offspring: More offspring are produced than can survive, but the population remains fairly constant. 3. STRUGGLE FOR EXISTENCE: Competition for food, space, mates (limiting factors). 4. NATURAL SELECTION –the best adapted are ‘selected’. Survival of the Fittest = best suited for the environment Darwin’s Fittest = Differential Reproductive Success *HW Ch 18
DESCENT OF MODIFICATION: Similarities in related species are due to common ancestry Idea of ‘common descent’ was inspired by BIOGEOGRAPHY (geographical distribution of species) Natural Selection favors Reproductive Success of certain individuals over others in a population. Individuals do not evolve, populations do
The study of the past and present geographic distribution of organisms. DARWIN: Species found on ocean islands tend to resemble species of the nearest mainland, even if the environment is different. Galapagos (South America) Cape Verde Island (Africa) AUSTRALIA: (separate land mass for millions of years). Has distinctive organisms not found anywhere else in the world even though climate is the same. Monotremes: Marsupials HHMS-Mice Natural Selection
Review timelines lab assignment and completed timelines in the classroom ◦ NOTE: 1 Meter stick = 1 Billion Years 4.6 Billion (Age of Earth) = ? 10 cm = ?..........1 cm = ?.........1 mm = 1 million years DAY 3 Textbook….Ch 21
CAN ALSO BE DEFINED AS: Any change in the frequency of alleles from one generation to another. A change in the gene pool of a population over time. A change in frequencies of alleles in the gene pool of a population. Ch 19 -text
MICROEVOLUTION: Genes Mutate Individuals are selected Populations evolve MACROEVOLUTION: LARGE changes, as when new species are formed. Can SEE the changes
The study of genetic variability within a population and the evolutionary forces that act on it. Distinguishes genetic equilibrium* from evolutionary change (*relates to the HARDY-WIENBERG PRINCIPLE; ‘population is at equilibrium’)
1. Genetic Drift – due to chance; relates to size of the population; causes a decrease in variation within the population; Ex- Bottleneck effect; founder effect 2. Gene Flow – relates to isolation; increases variation within a population; Ex- Immigration/Emigration 3. Mutation – substitution of alleles 4. Non-random mating – Ex- Inbreeding (self- pollinating plants); assortive mating (like:like) 5. Natural Selection – differential success in reproduction; only cause likely to be adaptive. (Pop. Genetics Handout, slides) *(These are the ANTITHESIS of H-W conditions)
Genetic Drift: random Gene flow: random migration http://evolution.berkeley.edu Mutation: random Variation ~ Differential Reprod. ~ Heredity Genetic Shuffling; Non-random* Mating 1 2 3 4 5 Adaptive; Not Random Evolutionary Fitness- The number of surviving offspring left to produce the next generation; measure of evolutionary success
Explain the increased frequency of dark moths during the 1880’s in Britain. Explain the decreased frequency of dark (melanic) moths from 1960’s to 80’s Other ways humans have had an impact on variation in other species (or our own)?
Essentially, went from Punnett Square/Mendelian predictions of the probability of specific offspring genotypes based on parental genotypes to determining expected allelic frequencies for entire populations. This definition of evolution was developed largely as a result of independent work in the early 20th century by Godfrey Hardy, an English mathematician, and Wilhelm Weinberg, a German physician. Through mathematical modeling based on probability, they concluded in 1908 that gene pool frequencies are inherently stable but that evolution should be expected in all populations virtually all of the time. They resolved this apparent paradox by analyzing the net effects of potential evolutionary mechanisms. Hardy 1877-1947 Weinberg 1862-1937 The mathematical prediction that allele frequencies do not change from generation to generation in a large population in the absence of micro- evolutionary processes (mutation, genetic drift, etc.) Does NOT exist in nature, however, provides: A means to calculate allelic frequencies A baseline for comparison (non-evolving population to an evolving population)
1. We have a very large population size 2. Isolation from other populations exists (no emigration/immigration) 3. There are no net mutations 4. There is random mating; all breed and produce the same number of offspring 5. There is no natural selection (Handout)
HW formula on the AP Equations Handout p + q = 1 p (dom trait) + q (rec) = 1 (p + q) 2 = p 2 + 2pq +q 2 = 1 WHERE: In a population…. p = freq of the Dominant allele q = freq of the Recessive allele p 2 = freq of individual AA q 2 = freq of individual aa 2pq = freq of individual Aa Diagram of Hardy-Weinberg genotype proportions from male (sperm) and female (egg) contributions. Given a locus with two alleles designated A and a that occur with frequencies p and q, the chart shows the genotype frequencies (p 2, 2pq, and q 2 ) as differently colored areas. Note that the heterozygotes (blue + yellow = green) can be formed in two different ways.
Albinism is a rare genetically inherited trait that is only expressed in the phenotype of homozygous recessive individuals (aa). The most characteristic symptom is a marked deficiency in the skin and hair pigment melanin. This condition can occur among any human group as well as among other animal species. The average human frequency of albinism in North America is only about 1 in 20,000. What have we been given?: Referring back to the Hardy-Weinberg equation (p² + 2pq + q² = 1), the frequency of homozygous recessive individuals (aa) in a population is q². Therefore, in North America the following must be true for albinism: q² = 1/20,000 =.0005 What can we find out from this information? By taking the square root of both sides of this equation, we get: (rounded off) q =.007 In other words, the frequency of the recessive albinism allele (a) is.00707 or ~1 in 140. With this information, what can we solve for? Knowing one of the two variables (q) in the Hardy-Weinberg equation, it is easy to solve for the other (p). P = 1 – q = 1 -.007 =.993 The frequency of the dominant, normal allele (A) is, therefore,.99293 or about 99 in 100. How can we use this information to determine genotypic frequencies? The next step is to plug the frequencies of p and q into the Hardy-Weinberg equation: p² + 2pq + q² = 1 (.993)² + 2 (.993)(.007) + (.007)² = 1.986 +.014 +.00005 = 1 p² (AA) = 98.6% No ‘a’ allele 2pq (Aa) = 1.4% carriers q² (aa) =.005% Albinos
REVIEW WORKSHEET- Problems 1-8,10 front, 1-6 back TEXT p415 1,2 (3) **QUIZ: Day 5 **Given a Phenotype = p 2, q 2, 2pq Allele/Gene Frequency = p,q DAY 3-4
The types of selection relate to the bell curve. The bell curve is altered due to forces of nature favoring certain traits over other. Text p419-21 Day 4
Clutch size (amount of eggs laid) in starlings is between 3 and 6. Clutch size is a genetic trait Human Birth Weight: The optimum birth weight is the one with the lowest mortality weight
Galapagos finches- extended drought, wet periods. The male widowbird collects females for his “harem” by attracting them by the length of his tail. The longer the tail, the more females he attracts and mates with. Rock Pocket Mouse HHMI- Rock Pocket Mouse 10.25
Relatively rare Galapagos Finches Male salmon mate at either 2 years old (Jacks) or 3 yo (hooknoses). Males fight over who will fertilize the female’s eggs. The male salmon are either very small or very large, very few are average size.
Text p424 Gradual change in genotype and phenotype through a series of geographically separated populations as a result of an environmental gradient
The creation of a new species. Evolution of a new species when a population becomes isolated from other members of the species. Scientists put every living thing in one of 8 different taxonomic groups: DOMAIN KINGDOM PHYLUM CLASS ORDER FAMILY GENUS SPECIESHUMANS? Beak of the Finch 15.54
REPRODUCTIVE ISOLATING MECHANISMS Prevention of interbreeding between two different species whose ranges (habitats) overlap. Most species have two or more mechanisms that block a chance occurrence of interbreeding between closely related species.
I.PREZYGOTIC BARRIERS: Barriers in place to prevent fertilization/ mating of two different species 1. Temporal isolation 2. Habitat isolation 3. Behavioral Isolation 4. Mechanical Isolation 5. Gametic Isolation TEXT p430
II.POSTZYGOTIC BARRIERS: Functions after fertilization, prevents development of viable, fertile offspring 1. Reduced Hybrid Viability 2. Hybrid Sterility 3. Hybrid Breakdown TEXT p430-431 *Preserve genetic integrity of a species by preventing gene flow
Two species of garter snakes: one lives mainly in water while the other is mainly terrestrial. The eastern spotted skunk mates in late winter; the western spotted skunk mates in late summer.eastern spotted skunk Blue-footed boobies of the Galapagos perform a courtship display unique to the species. Boobies: These 2 species of snails have opposite spirals in their shells so their genital openings are not aligned. http://bio1151b.nicerweb.net/Locked/media/ch24/
Gametes of red and purple sea urchins are released into the water, but are unable to fuse. Some salamander subspecies of the genus Ensatina can hybridize, but hybrids do not complete development or are frail. A mule is the robust but sterile hybrid between a male donkey and a female horse. Hybrids of two rice strains are vigorous and fertile, but the next generation (center) may be sterile.
I.Allopatric Speciation: “Different /native land” Subpopulation becomes physically separated from the original population…how? 1. Mountains emerge 2. Glaciers migrating 3. Land Bridges Develop 4. Rivers Shift TEXT p433 *Most Common Method of speciation, especially in animals
II. Sympatric Speciation: “ Together/native land” New species develops in the same geographic region as the parent population ◦ **Common in Plants ◦ Polyploidy (2 or more chromosome sets) ◦ Allopolyploidy (interspecific hybrid- multiple sets of chromosomes from 2 or more species) TEXT p435, fig 20-9 * Can occur in animals, but how is debated. (Not due to polyploidy)
1. New species may not compete successfully with parent species; goes extinct 2. New species may co-exist with the parent species 3. New species may outcompete parent species; hybrid may replace the parent(s) TEXT p436, fig 20-10
Geographic Isolation Kaibab Squirrels- Gr.Canyon Common in plants; change in ploidy (# chromosomes) and ecology 80% of all flowering plants- polyploids hybridization Lizards in an evolutionary tree 17.45
I. Gradualism: Continuous over long periods of time; gradual accumulation of adaptive characteristics 2. Punctuated Equilibrium long periods of stasis interrupted by short* periods of rapid speciation (*’short’may be thousands of years) TEXT p438 *
Large-scale phenotype in populations warrant their placement in taxonomic groups at the species level and higher. Dramatic evolutionary changes that occur over long time spans. Dominated by multiple microevolutionary processes or external, chance events…or both? Important Aspects of Macroevolution: 1. Appearance of evolutionary novelties 2. Adaptive Radiation 3. Mass Extinction Also related: 4. Earth’s Geological History Ch 20 p439
Huge differences in phenotype leading to different taxonomic groups. Comes from pre-existing structures….examples? Jointed appendages, feathers Originate from modifications of pre-existing structures May be due to: Changes in control/regulatory genes (on/off switch) Preadaptions (changed from one role/repurposed) Changes in Allometric Growth “different measure” Paedomorphosis “child form” Epigenetics 1.47 Epigenetics and Gene ExpressionEpigenetics and Gene Expression utah.edu
Due to Allometric Growth Varied rates of growth for different body parts Examples… (Text p440) sunfish Skull Fiddler crab T Rex
When juvenile characteristics are retained into the adult stage This is an example of varied changes in timing of development Text p 440
The evolutionary diversification of many related species from one or a few ancestral species in a relatively short period. Adaptive zones- new ecological opportunities. *Divergent Evolution
Opening of ‘adaptive zones’ – allowed for new species to develop