Bio 102 1/26-1/28 Notes
Bio 102 1/26-1/28 Notes Bio 102
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This 8 page Class Notes was uploaded by Alyssa Shriver on Tuesday February 2, 2016. The Class Notes belongs to Bio 102 at University of Tennessee - Knoxville taught by Dr. Jeremy Chandler in Spring 2016. Since its upload, it has received 21 views. For similar materials see Introduction to Biology in Biology at University of Tennessee - Knoxville.
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Date Created: 02/02/16
Lecture 1/28/16 Today in science o Sex wars: ant queens take sperm from males of other species Rock pocket mice o Valley of Fires Recreation Area, NM o The mice coat camouflages them from predators MC1R Gene o Lighter mice have two copies of the light allele o Darker mice have one copy or two copies of the black allele Variation and time o How often does a black coat mutation arise? Depends on Mutation rate Reproduction rate Population size Mutation Rate 2 per 10^9 sites in DNA Possible mutation sites in fur gene= 10 Number of copies of fur genes= 2 1 in 25 million offspring have a black coat mutation o Now factor in rate of reproduction: per year >5 offspring o Population size >5,000 females o Total offspring per year= 25,000 o Odd of black mutation: 1 in 25 million o 1 black mouse every 2500 years Is 1 black mouse per 1000 years a high mutation rate? o No Selection and time o How long would it take for every mouse to be black? Depends on S is the selection coefficient S is a relative measure of fitness S is successful at reproducing Is a black mouse produced 101 survivors out of 100 light colored mouse Nonadaptive Evolution o Genetic Drift Change in allele frequencies between generations that occur purely by chance Subset of population reproduces Subset of alleles represented in next generation Decreases genetic diversity of a population Gene Flow o Movement of alleles from one population to another o Urbanization can prevent gene flow, can lead to inbreeding Why is genetic diversity important? o Diverse gene pool gives a population more flexibility to survive in a changing environment o The more genetically diverse a population, the more ways it has to adapt Reintroducing genetic diversity o Must bring in new alleles o Mutation o Gene flow Inbreeding o Mating between closely related individuals o Does not change the allele frequency within a population o Increases the proportion of homozygous individuals to heterozygotes o Ex. Charles Darwin’s marriage Inbreeding Depression o Closely related individuals are more likely to share the same alleles o Negative reproductive consequences for a population o Associated with high frequency of homozygous individuals possessing harmful recessive alleles The Florida Panther o In 1990’s around 30 or less members of the population remaining o Many of the remaining individuals were sick and a multitude of defects ranging from crooked tails to heart conditions in addition to poor sperm quality o In 1995 8 female pumas from Texas were brought in to bolster the population Adaptive and Nonadaptive Mechanisms of Evolution o Natural Selection Individuals with favorable alleles reproduce preferentially, increasing the frequency of these alleles Adaptive Usually genetic diversity decreases—unfavorable alleles may be eliminated from the population o Mutation New alleles are created randomly Nonadaptive Usually genetic diversity increases—new alleles are introduced into the population o Genetic Drift Allele frequencies change due to chance events Nonadaptive Genetic diversity usually decreases—alleles may be eliminated from the population o Gene Flow Alleles move from one population to another Nonadaptive Genetic diversity increases—new alleles are added to the population Homozygous vs. heterozygous review o Tt heterozygous (hybrid) o BB homozygous dominant o Bb homozygous recessive o TT homozygous dominant o Tt homozygous recessive o Bb heterozygous (hybrid) HardyWeinberg equilibrium o In a nonevolving population, allele and genotype frequencies do not change over time o Use to identify genes that have changed because of evolutionary mechanisms o Baseline to judge if a population is evolving o HardyWeinberg equation P2+2pq+q2=1 P2 is the frequency of homozygous dominant 2pq is the frequency of heterozygotes q2 is the frequency of homozygous recessives o Five necessary conditions No mutation introducing new alleles into the population No natural selection favoring some alleles over others An infinitely large population size (and, therefore, no genetic drift) No influx of alleles from neighboring populations (i.e. no gene flow) Random mating of individuals What is a species? o Biological species concept A population of individuals whose members can interbreed and produce fertile offspring Different species cannot mate because they are reproductively isolated 1/26/16 Lecture The Voyage of the Beagle, Evolution, and Speciation What’s the main reason for genetic diversity? o DNA Robert Fitzroy o Captain of the Beagle o Devout in religious beliefs Science of the day theologians o Debated with Darwin on the cruise Alexander von Humboldt o Geologists John Henslow o Darwin’s primary mentor at Cambridge University o Botanist Contributor’s to Darwin’s thinking included: o Charles Lyell Geologist, uniformitarianism The Earth is older than 6,000 years o George Cuvier First to say species go extinct o Thomas Malthus Struggle for existence Carrying capacity: J curve/ S curve o Jean Baptiste de Lamarck Evolution by acquired characteristics First evolution theory Giraffes get taller due to stretching Alfred Russel Wallace Independently Drew the Same Conclusions as Darwin o Papers from Wallace and Darwin were jointly presented to the Linnaean Society in 1858 The Second Voyage of the Beagle o 18311836 o Different species on different islands o Origin of species study Dust collected from the masthead on the Beagle o Some of the original samples were added to growth medium and cultivated viable organisms after over one hundred of years in storage Numerous fungi, bacteria were found There are the same organisms everywhere in the world, but once they get to a place, natural selection occurs and decides whether or not the organism thrives or doesn’t Bioluminescence is when oxygen in high concentrations can be harmful to microorganisms Darwin visited Brazil’s Atlantic rainforest before lodging began, and discovered the incredible diversity of its flora and fauna which differed greatly from Great Britain’s. Discomfort with Evolution o The upheaval surrounding evolution began with publication of On the Origin of Species and continues nearly 150 later o An early disparaging view of evolutionary theory and its creator An early disparaging view of evolutionary theory and its creator. Darwin’s voyage of the Beagle o In Argentina he found fossils of extinct mammals and discovered that they were closely related to species that no longer existed What percent of species are extinct? o 99% o Most of the extinctions are what we call “background extinctions” Background Extinction o The ongoing extinction of individual species due to environmental or ecological factors such as climate change, disease, loss of habitat, or competitive disadvantage in relation to other species. Background extinction occurs at a fairly steady rate over geological time and is the result of normal evolutionary processes, with only a limited number of species in an ecosystem being affected at any one time. Voyage to the Galapagos Islands o In the Galapagos Islands he discovered that animals like birds and turtles differed slightly from one island to another o The HMS Beagle stayed at the Galapagos Islands from September 15 through October 20, 1835 Galapagos Giant Tortoises o Galapagos in Spanish for saddle/tortoise o Although the Galapagos tortoises looked pretty much alike to Darwin, Nicholas Dawson, the Englishman in charge of Ecuador’s penal colony on Charles Island, told Darwin that he could tell which island any particular tortoise cam from, because there were slight differences from one island to the next. o Again, the significance of this was no evident to Darwin until after he had returned to England and thought about it Galapagos Island finches o Four species of finches found on the Galapagos Islands o Darwin did not realize they were all finches, but the English ornithologist John Gould told him they were; Gould identified a total of 13 different species among Darwin’s specimens o The Galapagos finches have been extensively studied since Darwin’s time, and their evolution (back and forth) recorded Galapagos Marine Iguanas o Their diet consists of mostly seaweed, which is unusual for land animals such as the iguana o Their feet are webbed so they can swim in the sea o On land they are sluggish in movements but swim with ease and quickness in the sea o They regulate their temperature by either laying flat on the lava to catch the heat or perching up to catch the breeze o The brightly colored lizards are colored that way from eating plentiful seaweed and this attracts female lizards because the male is healthy therefore the offspring with be healthy o Colors due from algal blooms in summer and feeding on those blooms El Nino Effect on marine iguanas? o Dries up all the algal, therefore all the iguanas starve and more than 99% of the iguanas die off The Galapagos Islands o “Both in space and time, we seem to be brought somewhat near to that great fact that mystery of mysteries the first appearance of new beings on this Earth” o Darwin’s notebooks on the voyage of the Beagle totaled to 1,383 pages on geology, and 368 pages on zoology What comes to mind when you see the word “ecosystem”? o Life o Animals o Plants o Environment o Habitat o Other Urban Evolution o Studying evolution in Manhattan Population genetics o Study of the genetic makeup if populations and how genetic composition changes o Gene pool; total collection of alleles in a population o Identify allele frequency o If the gene pol changes over the course of generations, then evolution has occurred o Changes in allele frequency over time o Population evolves o Good, bad, or neutral consequences result in the population becoming more adapted to its environmentnatural selection results in a population adapting What causes changes in allele frequency? o Natural Selection Population is better adapted o Nonadaptive Evolution Caused by mutation, genetic drift, and gene flow Nonadaptive Evolution o Genetic Drift Changes in allele frequencies between generations that occurs purely by chance Subset of population reproduces Subset of alleles represented in next generation Decreases genetic diversity of a population Evidence for Genetic Drift o Researchers collected tail DNA from 312 mice at 15 locations in NYC. One they analyzed each mouse’s DNA, the researchers wanted to get a sense of how related the populations were. They assigned mice with similar genotypes particular colors and sorted all the mice by location. They found that mice within a population shared more alleles with one another than they did with mice from other populations.
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