BIO 152 1st Edition Lecture 19Outline of Last LectureII. Action PotentialIII. SynapsesOutline of Current LectureI. Evolution A. Definitions and Preconditions 1. Common Misconceptions B. Artificial Selection 1. Domestication Syndrome Current LectureEvolution IDefinitions and Preconditions- evolution: over time species accumulate differences, thusdescendants are different from ancestors - whale evolution example - change in species over time (many generations) but says nothing aboutwhere these came from (natural selection, genetic drift, randommutations etc) Mechanisms that can lead to evolutionnatural selection: gradual, non-random process by which traits become more or less common in a species based on differential reproduction- artificial selection: non-random process by which traits become more or less common in a species because humans are selecting which organisms These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.have offspring What must be true for evolution through natural selection? - variation in traits must exist in population- can be phenotypic (like a bigger nose) - a protein difference (technically phenotypic but it is not visible) - must lead to differences among lifetime reproductive success - must be genetically transmutable to the next generation **Clicker Question**Selection of pinto beans — size and number shown in graphs on lecture slides. If you wanted to get bigger beans in the third generation, which population would you select from?- answer is D - the mean has moved and has gotten larger when compared to theparental population - don’t want to select from B (or A) because you’ve already donethat, you’re looking for a new selection Why don’t the second generation of beans from group A change size?- A and B are different strains of pinto beans (different geneticbackgrounds) - selected the larger beans and are not seeing them passed on to the nextgeneration - they were already selected for, however even then the trait was notshown in the offspring — means that the trait is non-heritable - in B, the same trait was being selected for, however in that population thetrait was heritable - size should be heritable and usually would be — if you have a field thatisgenetically identical, you will still see phenotypic differences - phenotype and genotype are linked but are not always the same **Clicker Question**What happened in group B?- artificial selection (if evolution was an option that would also be correct, however its evolution by artificial selection, not natural selection- not genetic drift because it is a non-random event (genetic drift must berandom) gene flow is just when a new population mixes with another population and they inter-mateCommon Misconceptions- there is no intentionality (in natural selection), an organism does notdevelop a trait in order to deal with an environmental challenge - change is random, selection is not — changes in the genome, mutationsunderlying genetic variability are random, but what genes are selected foris not random - fitness has to do with reproductive success, not strongest, healthiest,fastest etc. all adaptations are not a perfect fit for an environment, they work with whatthey haveArtificial Selection: proof of concept- if a scientist were to discover dog skeletons thousands of years into thefuture, the large dog might be considered a different species than thesmall dog - because of variability in the genome - some organisms have a wide variability in traits and this allowsfor great differences - cabbage, broccoli, brussels sprouts etc. are all the same species selections for different traits led to all those differences (artificial selection)- **Clicker Question** Irish potato blight caused by organism that infects plants and kills them. Onthe left of the picture in the slides is a resistant plot of potatoes (transgenic,so a gene from a wild potato inserted into the cultivated potato genome) and the right side are non-transgenic potatoes (transgenic are growing fine,and non-transgenic aren’t growing). - Is this an example of evolution? there is a reproductive advantage, the descendants differ from the ancestors (but it is notnatural selection, it is artificial selection), this is a heritable change but instead of coming from a mutation from traditional breeding, you have inserted the gene - but it is still evolution because the species has changedbecause of this Video on Foxes- selected against aggressive behavior in one group and foraggressive behavior in another group - how dogs might have been selected from wolves - showed the difference between tame and aggressive foxes is in theirgenes — had nothing to do with the behavior of the mothers - normal pattern and colored coat changed in some of the foxes - shorter limbs and tails, some kept curled ears and their tales curled —tame foxes beginning to look more like dogs Domestication syndrome: there is suite of traits that tend to go along with domesticated animals (occurs in all animals even though they’re domesticated separately)- floppy ears - shortened snout - pigmentation changes- smaller teeth what you’re ultimately selecting for is less secretion from the adrenal gland,so in delaying the migration of cells to the adrenal gland in infancy, you get a smaller brain, don’t get as much cartilage in the ears etc. (so all these traits happen because of what the selection does to the adrenal