Evolution

1. Evolution

2. Earth’s history as a clock Ceno-zoic Meso-zoic Paleozoic Humans Land plants Origin of solar system and Earth Animals 4 1 Proterozoic Eon Archaean Eon Billions of years ago 2 3 Multicellular eukaryotes Prokaryotes Single-celled eukaryotes Atmospheric oxygen

3. Properties of Life • Organisms: • Do not spontaneously generate • Are composed of cells • Acquire and use energy • Grow and develop • Reproduce • Interact with their environment • Populations evolve (A population is a group of organisms of the same species living in the same geographic area. There is genetic variation in all populations. Individual organisms do not evolve.)

4. Evolution • Charles Darwin’s view of life as expressed in The Origin of Species (1859) contrasted sharply with the traditional beliefs of an Earth that was only a few thousand years old, populated by forms of life that had been created at the beginning and that remained unchanged. • Evolution is fundamental to the study of biology • Evolution is defined as a change in the gene pool of a population • A gene pool is the total group of genes in a population at any one time.

5. Mechanism of Evolution • All populations live in an environment • Population members compete for resources - try to survive and reproduce • Within every population there is genetic variation • Due to this variation, some members of the population will be able to survive and reproduce more successfully in their environment than other members of the population

6. Variation in a population: polymorphism

7. Mechanism of Evolution Organisms that best survive and reproduce in their environment pass their genes on, while organisms with disadvantageous traits will not A population’s gene pool can change over generations if individuals with certain heritable traits produce more viable offspring than other individuals. The process of differential survival and reproduction is known as natural selection The fitness of an organism refers to the contribution it makes to the gene pool of the next generation relative to the contributions of the other members of the population. In other words, a more fit organism survives and reproduces. Natural selection depends on the environment.

8. Artificial Selection Artificial selection is done by breeders; species are modified by humans. Plants and animals are specifically chosen to breed with the desired goal of producing offspring with a specific characteristics. Another example: wild mustard

9. Lateral buds Terminal bud Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Kale Stem Flower and stems Broccoli Wild mustard Kohlrabi Artificial selection

10. Examples of Evolution • There are several classic examples of evolution • The English peppered moth

11. Examples of Evolution There are contemporary examples of evolution as well For each of the following below, think about and discuss how evolution occurs, using the phrases variation in the population, differential survival success, differential reproductive success, change in the gene pool of the population and evolution due to natural selection Antibiotic-resistant strains of bacteria Herbicide-resistant varieties of plants Pesticide-resistant varieties of insects

12. Levels of Evolution • Microevolution is the change in the genetic makeup of a population from generation to generation. It refers to adaptations that are confined to a single gene pool. • Macroevolution refers to evolutionary change greater than a single gene pool, such as the appearance of feathers, that is used to define higher classifications (e.g., domain, kingdom, phylum, class)

13. Speciation • Natural selection can give rise to new species. • If the environment changes over time, or if individuals of a particular species move to a new environment, natural selection may result in adaptations to these new conditions, and ultimately in new species. • Adaptive radiation occurs when many new species arise from a single common ancestor • Adaptive radiation typically occurs when a few organisms make their way to new, distant areas or when environmental changes cause numerous extinctions, opening up ecological niches for the survivors. • Adaptive radiation an occur gradually or in geologically “short” periods of time.

14. (a) Cactus eater. The long,sharp beak of the cactusground finch (Geospizascandens) helps it tearand eat cactus flowersand pulp. (c) Seed eater. The large groundfinch (Geospiza magnirostris)has a large beak adapted forcracking seeds that fall fromplants to the ground. (b) Insect eater. The green warbler finch (Certhidea olivacea) uses itsnarrow, pointed beak to grasp insects. Beak variation in Galápagos finches

15. Time (b) (a) Gradualism model. Species descended from a common ancestor gradually diverge more and more in their morphology as they acquire unique adaptations. Punctuated equilibrium model. A new species changes most as it buds from a parent species and then changes little for the rest of its existence. Two models for the rate of speciation

16. Mutations • Mutations are changes in the DNA (i.e., genes) of organisms • These can be caused by chemicals, UV radiation, X-rays, and other forms of radioactivity • Depending on where the mutation occurs and how extensive it is, the organism could • die • survive with no changes • survive with changes but not pass the changes on • survive and pass on the changes to offspring

17. Genetic Engineering/Genetic Modification Biotechnology is the process of manipulating organisms or their components for the purpose of making useful products. Genetic engineering is the process of manipulating genes and genomes & often includes making recombinant DNA. Recombinant DNA is DNA that has been artificially made, using DNA from different sources and different species. An example is the introduction a human gene into an E. coli bacterium to make large quantities of insulin. Agriculture has been making use of GE technology for about 20 years

18. 2 1 3 Genes conferring useful traits, such as pest resistance, herbicide resistance, delayed ripening, and increased nutritional value, can be transferred from one plant variety or species to another using the Ti plasmid as a vector. Agrobacterium tumefaciens RESULT APPLICATION TECHNIQUE Tiplasmid Site where restriction enzyme cuts The Ti plasmid is isolated from the bacterium Agrobacterium tumefaciens. The segment of the plasmid that integrates into the genome of host cells is called T DNA. T DNA DNA with the gene of interest Isolated plasmids and foreign DNA containing a gene of interest are incubated with a restriction enzyme that cuts in the middle of T DNA. After base pairing occurs between the sticky ends of the plasmids and foreign DNA fragments, DNA ligase is added. Some of the resulting stable recombinant plasmids contain the gene of interest. Recombinant Ti plasmid Recombinant plasmids can be returned to Agrobacterium, which is then applied as a liquid suspension to the leaves of susceptible plants, infecting them. Once a plasmid is taken into a plant cell, its T DNA integrates into the cell‘s chromosomal DNA. Transformed cells carrying the transgene of interest can regenerate complete plants that exhibit the new trait conferred by the transgene. Plant with new trait Transgenic plants

19. A tobacco plant expressing a firefly gene

20. Genetic Engineering Issues How does GE technology work? How is GE technology similar to traditional selective breeding techniques? How is it different? What were some of the concerns demonstrated in the video and in the readings?  What were the pros and cons of this technology as identified in the video and the readings?  What recommendations would you make regarding the implementation of this technology? What other information would you like to know?

21. Biodiversity & Extinction

22. Biodiversity • To date, approximately 1.8 million species have been discovered • About 13,000 new species are discovered every year • An estimated 4 to 40 million species may actually inhabit our planet • 99% of all the species that have ever existed are extinct, yet we currently have the greatest diversity of life in geologic history • We are in the 6th great extinction episode, with the current extinction rate about 27,000 species per year • The cause of this massive extinction – humans (HIPPO) • Normal extinction rate is between 20 & 30 species per year

23. Extinction • The current rate of extinction is exceptional - 100 to 1000 times greater than normal • On average, a distinct plant or animal species becomes extinct every 20 minutes, and may be as high as 130 species extinctions per day • More than 11,000 plant and animal species, including 24% of all mammals, are in immediate danger of extinction due to human activities

24. Small population Genetic drift Inbreeding Lower reproduction Higher mortality Loss of genetic variability Reduction in individual fitness and population adaptability Smaller population Extinction Vortex

25. Extinction • There have been 5 great extinction periods in geologic history, with the most recent occurring 65 million years ago • These periods are loosely defined as times when more than half of all species become extinct • After each extinction, it took upwards of 10 million years for species richness to recover • Even when biodiversity is restored, once a particular species is extinct it is gone forever • Cycles of extinction followed by speciation can be influenced by changes in climate (due to meteorite or asteroid collisions), continental drift, and currently – by human actions

26. John C. Sawhill Nature Conservancy “In the end, our society will be defined not only by what we create, but by what we refuse to destroy.”