Unit 3, Week 3: Evolution
Unit 3, Week 3: Evolution BIOL 1108
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This 7 page Class Notes was uploaded by Skyler Tuholski on Monday October 26, 2015. The Class Notes belongs to BIOL 1108 at University of Georgia taught by Dr. Farmer in Fall 2015. Since its upload, it has received 173 views.
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Date Created: 10/26/15
Evolution Monday October 19 2 15 1222 PM IN THE NEWS Who s your great 40000 y o grandpa from Johannesburg South Africa 0 Homo naledi O 0000 0 Found in the back chamber of a cave in South Africa along with 15 other bodies from babies to elderly Skull shape similar to early Homo species Possibly the earliest branch of our lineage There were 5 or 6 different hominid species living in that part of Africa In order to get their bones way back into that chamber they had to be carried by someone I Evidence of intentional burial This is the first time this species has been identified 0 Guest speaker Hannah Morris O 0000 Brain was a little smaller than ours about the size of orange Shoulder and trunk are more primitive Fingers are long and curved more like Australopithecus Feet are just a tiny bit flatter Overall they are very similar to us Evolution Learning Objectives What is a chromosome What is a karyotype What produces a banding pattern on chromosomes How can a karyotype be used to make comparisons between different taxa How does a karyotype compare to gene sequencing 0 Clicker Question Who was the first person to suggest that humans and the other great apes be grouped together 0 Carolus Linnaeus I Swedish naturalist who categorized all living things today I Defined our genus originally as Homo diurnis man of the day and homo nocturnus man of the night orangutans SO he included the orangutan in with the same group as humans I Gorillas weren39t included because Westerners didn39t know about gorillas I He knew grouping primates and humans would cause controversy but didn39t know any reason for separating them I 100 years later in 1850 Charles Darwin published the Origin of Species I All the theologians went against Darwin for his idea of evolution 0 Clicker Question What is the primary reason that some people have difficulty accepting that humans and the other great apes share a common ancestor O RELIGION Biology Page 1 Humans and chimpanzees are almost 99 identical genetically 0 They also have nearly identical muscle groups and even an appendix 1871 Charles Darwin wrote The Descent of Man that acknowledged similarity between humans and many other apes 0 Claim based on comparative anatomy 0 Behavior of animal had humanlike interactions 0 They have the same types of behaviors and emotions that we do kindness jealousy laughter mourning rage empathy Lucy O Australopithecus afarensis 0 Found in Ethiopia 32 mya 0 Adult female quot25 yo 0 Bipedal walked on 2 feet like us Clicker Question How did scientists do comparative genetics before DNA sequencing was invented in the 19703 0 By looking directly at genes under a microscope WaldeyerHartz and others used a staining technique that allowed him to visualize chromosomes in cells that were about to undergo division so at metaphase 0 Used Hematoxylin a compound extracted from the heartwood of the logwood tree to stain I Giemsa stain is used in quotGbandingquot to stain chromosomes because it attaches itself to AT regions of DNA well 0 Created karyotype number and appearance of chromosomes in nucleus of eukaryotic cell 0 Humans 22 pairs of autosomal chromosomes and 1 pair of sex chromosomes 0 Chromosome banding technique shows bands that distinguish between species or compare genes within a species I Focus on length the position of the centromeres banding pattern and any other physical characteristics Banded chromosome Dark bands are A T or G C rich 0 KaryotypIng still used In InVItro fertilization CnCS because It quIckly spots trIsomy events and broken chromosomes that broke during crossing over O Karyotypes can also be used to construct phylogenies Biology Page 2 Biology Page 3 1 K 1 2 3 u 1 I 1 II J 3 H7 39 I 6 7 8 9 10 11 12 n M 0 3i 2 n 13 14 1s 16 17 18 In 4 15 19 2O 21 22 Ka ryotype I a 10262015 Human Evolution Monday ctober 26 2615 1156 AM Learning Objectives What is meant by the term hominid What evidence supports the idea that humans and the other great apes chimps bonobos gorillas orangutans all share a common ancestor In what ways can genetics inform us about the course of human evolution In terms of chromosomal similarity Humangt chimpgt gorillagt orangutan Humans do not have 2 functional centromeres on chromosome 2 like the chimps gorillas and orangutans do because humans have 46 chromosomes 23 pairs and all the other great apes have 48 24 pairs WHY o The ancestor of all the great apes had 48 and it39s been reduced in humans to 46 l i l1 Upl 39 E Much more likely Much less feaSIble Human 5 Human 451 E mmun Common grungestar E n ib H13 anteninr H39 nuh HE 45139 E hi mpa name 43 Chimpanzee 43 Gunilla ME Gunilla 4E Chromosome number Hiramme number reduction event increase we t o How could an entire chromosome be lost We didn39t lose it We fused chromosomes I Telomeres fused together but no DNA was lost bc telomeres do not code for proteins I All genes found on human chromosome 2 match up to 2 separate chromosomes that the great apes have We have found the hidden fused telomeres and the centromere within human chromosome 2gt that39s why we only have one centromere on chromosome 2 Biology Page 1 4 6 million years ago 6 8 million years ago 12 romnlron years ago 0 What other evidence is there for establishing a relationship between humans and the great apes Chimpanzee Ancient Hominid Human Fan Trogldd es Australopithews afarensis Homo Sapient FiquFE 159 W V Some skeletal iea lur ES ll an aus 39 r 3 T g b tralotil thetlru are r11 r rm 1 all in between thaw Ell ri l t j mes and lmn rans ramparta the skull and jzwlxrin horr of Airs lr l r ijiither E i lll39um a ElfENVELP39iitn Ell Wit h thle tin thirdl Araratblur Atel abulum l pumice iii and 7 Elle humane Elk 39 I J H a l schial ilS39cliial ischial tuberosity39 tuberosity tuber355W 0 Fossil similarities between modern humans ancient hominids and chimps o Genome sequence of chimpanzee is incredibly close to humans 0 The molecular clock suggests that certain genes will mutate at a rate of nucleotide change based on the organism We use radiometric dated fossil evidence to calibrate this quotclockquot This estimates how long ago one organism shared a common ancestor with another 0 ERV39s stay in genomes once incorporated They are inherited and accumulate We can identify ERV39s and say with certainty that chimps and humans share a common ancestor around 5 mya 0 Similar pathogens infect both chimps and humans HIV was transmitted to humans through contact Biology Page 2 O with chimps in Cameroon One strain of malaria can also affect us both Don39t look for what they have in common but how they differ 0 Guinea pigs apes some fruit bats and humans cannot make their own ascorbic acid Vit C but all other mammals can 0 O O In humans and apes the inability to make Vitamin C is due to a defective gene that no longer codes for an enzyme LGULO essential to making Vit C known as pseudogene LGULOP We have specific nucleotide changes that have rendered this gene nonfunctional same changes are present in chimps gorillas orangutan and macaque So humans and apes must be descended from a common ancestor that had that error pseudogene Consequences of no Vit C Scurvy 0 Clicker Question Why don39t humans and the great apes get scurvy if we don39t make Vitamin C 0 We get enough from our diets FRUIT 0 Parasites are another way to make evolutionary comparisons O O 0 Head lice and body lice appear to be different but genetically are determined to be the same species Claws on body lice are hooked but those of head lice are not This is so they can grab clothes Body lice are a strain that has evolved from the head licegt we can estimate this species divergence back to when humans started wearing clothes 4070000 years ago Body lice adapted to new environment and gained claws to be more successful in latching onto clothes Study of pubic lice suggests that human pubic lice are more closely related to gorilla pubic lice than chimps This means ancient humans were fooling around with gorillas But no progeny resulted because we have different numbers of chromosomes 0 Clicker Question What distinguishes our species Homo Sapiens from all other primates that have ever existed and from the other great apes 0 There really is nothing that distinguishes us from other primates 0 Human Evolution 0 O O O O O Footprint of Homo ergaster found in Africa It is 15 MYA and exhibits the same locomotion as we do Ardipithecus ramidus is a 44 mya skeleton found in Ethiopia I Bipedal I Upright but she did have a grasping toe She was probably standing up in trees I Teeth are between chimps and homo sapiens I Filed gap between chimps and austrilopithecines Lucy and her Australopithecus relatives used simple tools Homo habilis arose 25 mya and used tools Homo erectus arose 16 mya in Africa Used tools and fire Walked out of Africa Modern Homo sapiens evolved in Africa and migrated out of Africa 100000 yea rs ago Gene sequence from 2 teeth and 1 finger bone found in cave Denisovan Shows it is very different Biology Page 3 from both humans and Neanderthals according to mDNA Melanesians and Tibetans today still have Denisovan genes the different hemoglobin genes I A five nucleotide haplotype AGGAA is known only from Tibetans and Denisovans I This allele may Tibetans to live in a reduced oxygen atmosphere with the same amount of hemoglobin Hb as North Americans living at sea level whereas South Americans need more Hb O Neanderthals Ancestors evolve Neanderthals Researchers looked at into Neanderthals die out five groups of modern and first modern humans humans French Han Chinese Neanderthal Some Neanderthal and Homo saprens Papuen Interbreedlng Common ancestor mm Neandemm Some modern humans leave Afnca Yoruba Source Science Iournnl Note Time periods not to scale We interbred with Neanderthals and Denisovans Modern humans that are not of direct African descent have 14 Neanderthal genes Could Neanderthals speak Yes There is a gene that is essential for verbal communication Neanderthals had it They also had developed family and clan structures and practiced intentional burials They diverged from H Sapiens about 500000 years ago Biology Page 4
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