Lecture 10: Human Dispersal and Genetic Markers of Disease PDF

Human Dispersal and Genetic Markers of Disease Lecture 10 Announcements Email me an edited answer to earn back points that were taken off of the short answer questions Develop ≠ Evolve Deadline: October 22 Extra credit opportunity Complete this survey to earn 1 extra...

Human Dispersal and Genetic Markers of Disease Lecture 10 Announcements Email me an edited answer to earn back points that were taken off of the short answer questions Develop ≠ Evolve Deadline: October 22 Extra credit opportunity Complete this survey to earn 1 extra credit point on Exam 1: https:// docs.google.com/forms/d/e/1FAIpQLSesOag2 Vm4A_d8q0TGDz_fZYa65nzb4x1nFr2s4DkCPA kV52g/viewform?usp=sf_link Deadline: November 1 Some epigenetic marks are attached to the DNA molecule, but they do not regulate gene expression. Proximate vs Ultimate/Evolutionary Explanations Proximate explanations Address how the body works Answer what and how questions about structure or mechanism Most medical research seeks proximate explanations Proximate vs Ultimate/Evolutionary Explanations Ultimate/Evolutionary explanations Answers why questions about origins and functions Today’s Objectives Review what is known about human genetic variation Discuss direct-to-consumer genetic ancestry testing Terms and Concepts to Know Cline Population substructure Selective sweep Polygenic adaptation Haplogroup Reference population How can genetic tests reinforce or undermine the idea that race is a genetically determined category? Today’s Objectives Review what is known about human genetic variation Discuss direct-to-consumer genetic ancestry testing Anatomically Modern Humans Evolved in Africa 300-200 kya  Because Homo sapiens evolved in Africa and stuck around for a over 100,000 years, most human genetic diversity evolved in Africa Genetic diversity outside of Africa is a subset of what exists within the content due to founder effect and genetic drift 10 3 Main Critiques of Race as Genetically Determined Category 1. Human genetic variation is clinal 11 Clines and Substructure Cline - frequency of variants (alleles or phenotypes) is high in some geographic regions and gradually becomes less frequent as one moves away from that region 12 Clines and substructure Within clines there is population substructure Clustering of allele frequencies within a cline Due to nonrandom mating and periodic isolation 3 Main Critiques of Race as Genetically Determined Category 1. Human genetic variation is clinal 2. Most human genetic variation is discordant Meaning, the traits we use to distinguish race are independently inherited and have no value for predicting other aspects of biology 14 3 Main Critiques of Race as Genetically Determined Category 1. Human genetic variation is clinal 2. Most human genetic variation is discordant Meaning, the traits we use to distinguish race are independently inherited and have no value for predicting other aspects of biology 3. Human genetic variation is widely shared across the species, with little variation occurring between racially defined groups 15 How has natural selection shaped the human genome? Selective sweep When a beneficial novel mutation increases in frequency in a population through natural selection How has natural selection shaped the human genome? Selective sweep When a beneficial novel mutation increases in frequency in a population through natural selection Hard selective sweep model Humans migrate into new environments -> strong selection for novel beneficial mutations How has natural selection shaped the human genome? Selective sweep When a beneficial novel mutation increases in frequency in a population through natural selection Hard selective sweep model Humans migrate into new environments -> strong selection for novel beneficial mutations Polygenic adaptation Natural selection for multiple alleles that already existed in the population Each allele has a small effect on the adaptive phenotype A faster mode of adaptation How has natural selection shaped the human genome? Examples of selective sweeps in the human genome Skin pigmentation Metabolic adaptation to cold climates Lactose tolerance Infectious disease susceptibility Malaria and the sickle allele Adaptation to high altitude hypoxia Lecture 10 Quiz True or False: Genetic diversity outside of Africa is a subset of what exists within the continent due to founder effect and genetic drift. Today’s Objectives Review what is known about human genetic variation Discuss direct-to-consumer genetic ancestry testing “Racial experience in the age of direct-to-consumer ancestry testing” https://www.youtube.com/watch?v=IIWlat Qt4KE “DNA ancestry tests don’t actually tell us where our ancestors lived. They’re really just giving us probabilities of where we’re likely to have relatives today.” “Racial experience in the age of direct-to-consumer ancestry testing” How do genetic ancestry tests work? Compares test-taker’s haplogroups to the frequency of haplogroups in reference populations Haplogroup A group of similar haplotypes that share a common ancestor What haplogroups do you have? Which reference populations have a high frequency of your haplotypes? What is a reference population? Any population that serves as a comparison for a genetic ancestry analysis The genetic clustering in a reference population depends on which individuals are included in the database Haplotype Allele A Allele B Allele C “Racial experience in the age of direct-to-consumer ancestry testing” How do genetic ancestry tests work? Compares test-taker’s haplogroups to the frequency of those haplogroups in reference populations Haplogroup A group of similar haplotypes that share a common ancestor What haplogroups do you have? Which reference populations have a high frequency of your haplotypes? What is a reference population? Based on population substructure within a cline The genetic clustering in a reference population depends on which individuals are included the database “Racial experience in the age of direct-to-consumer ancestry testing” Changes in the reference group data can change the results of the test How are reference populations defined? Names of reference groups are shaped by history, culture, politics, and other social identities “Racial experience in the age of direct-to-consumer ancestry testing” Dr. Jada Benn Torres https://youtu.be/rZJCOhCfq3E?si=5ToTWiIm08OdBIyF https://www.youtube.com/watch?v=Ur7Fu2-jYAY&t=92s “Racial experience in the age of direct-to-consumer ancestry testing” Dr. Benn Torres argues that genetic ancestry testing can… reify biological notions of race empower communities by shaping racial experience What about “racial medicine”? Dr. Dorothy Roberts https:// www.youtube.com/watch?v=KxLMjn4WPBY