In March 2013, the American Journal of HumanGenetics published a report that an AfricanAmerican man who submitted his genome forcommercial genealogical analysis had a Y chromosome whose sequence was very different from thatof other Y chromosomes that had been characterized previously. The investigators then found thatcertain males among the Mbo (an ethnic group inCameroon) shared many of the polymorphisms firstfound in this African-American man. How do youthink these findings would have altered estimates ofwhen a man carrying the MRCA for the human Ychromosome would have lived on the earth?

In March 2013, the American Journal of HumanGenetics published a report that an AfricanAmerican man who submitted his genome forcommercial genealogical analysis had a Y chromosome whose sequence was very different from thatof other Y chromosomes that had been characterized previously. The investigators then found thatcertain males among the Mbo (an ethnic group inCameroon) shared many of the polymorphisms firstfound in this African-American man. How do youthink these findings would have altered estimates ofwhen a man carrying the MRCA for the human Ychromosome would have lived on the earth?

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter19: Evolutionary Change In Populations

Section: Chapter Questions

Problem 19TYU

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A species of antelope has 20 chromosomes per set. The species isdivided by a mountain range into two separate populations, whichwe will call the eastern and western population. In a comparison ofthe karyotypes of these two populations, it was discovered that themembers of the eastern population are homozygous for a largeinversion within chromosome 14. How would this inversion affectthe interbreeding between the two populations? Could such aninversion play an important role in speciation?
The distance between two molecular markers that are linked alongthe same chromosome can be determined by analyzing the outcomesof crosses. This can be done in humans by analyzing a family’spedigree. However, the accuracy of linkage mappingwith human pedigrees is fairly limited because the number of people in mostfamilies is relatively small. As an alternative, researchers can analyze a population of sperm, produced from a single male, and computelinkage distance in this manner. As an example, let’s suppose a maleis heterozygous for two polymorphic STSs. STS-1 exists in two sizes:234 bp and 198 bp. STS-2 also exists in two sizes: 423 bp and 322bp. A sample of sperm was collected from this man, and individualsperm were placed into 40 separate tubes. In other words, there wasone sperm in each tube. Believe it or not, PCR is sensitive enough toallow analysis of DNA in a single sperm! Into each of the 40 tubeswere added the primers that amplify STS-1 and STS-2, and then thesamples were…
The distance between two molecular markers that are linked alongthe same chromosome can be determined by analyzing the outcomesof crosses. This can be done in humans by analyzing a family’spedigree. However, the accuracy of linkage mapping in humanpedigrees is fairly limited because the number of people in mostfamilies is relatively small. As an alternative, researchers cananalyze a population of sperm, produced from a single male, andcompute linkage distance in this manner. As an example, let’ssuppose a male is heterozygous for two polymorphic STSs. STS-1exists in two sizes: 234 bp and 198 bp. STS-2 also exists in twosizes: 423 bp and 322 bp. A sample of sperm was collected fromthis man, and individual sperm were placed into 40 separate tubes.In other words, there was one sperm in each tube. Believe it or not,PCR is sensitive enough to allow analysis of DNA in a single sperm!Into each of the 40 tubes were added the primers that amplify STS-1and STS-2, and then the samples were…
Marcia saw an ad on television for ancestry DNA testingand thought, ”Why not?” She ordered a kit, swabbedher inner cheek, and returned the kit for analysis. Severalweeks later, she was surprised to learn that she was 17 percentNative American. An elderly great aunt confirmed that her mother’s family intermarried with members of Native American tribes in the Pacific Northwest in the early twentieth century. To investigate her maternal heritage, Marcia ordered a mitochondrial DNA (mtDNA) test, which confirmed her Native American ancestry. Based on these genetic results, she applied to several Native American tribes for enrollment as a tribal member. She was shocked when she was turned down. In discussions, tribal officials told her that DNA alone is not sufficient to define who is Native American. Tribal standards for enrollment vary, but usually cultural attributes such as knowledge of the language, customs, and history of the tribe are important considerations for enrollment decisions.…
Many modern people have some Neanderthal DNAin their genome, but the Neanderthal alleles are notuniformly distributed across their genome. A person ofEuropean or Asian ancestry typically has 1.5 to 2 percent Neanderthal DNA in their autosomes. However, researchers have never found any Neanderthal alleles on the Y chromosome of a modern human. By one hypothesis, Neanderthal Y alleles disappeared because theywere incompatible with H. sapiens genes. Explain howreduced fitness in hybrids arising from genetic incompatibility could have, over time, led to the elimination of theNeanderthal Y alleles from the H. sapiens gene pool.
Tay-Sachs disease is caused by loss-of-function mutations in a gene on chromosome 15 thatencodes a lysosomal enzyme. Tach-Sachs is inherited as a autosomal recessive conidition.Among Ashkenazi Jews of central European ancestry, about 1 in 3600 children is born withthe disease. What fraction of the individuals in this population are carriers? (Assume thepopulation is in Hardy-Weinberg equilibrium)
In the early 1970s, Igor Dawid and Antonie Blacklerconducted classical experiments that first showed directly the maternal inheritance of mtDNA in vertebrates.Their studies used crosses between two closely relatedspecies of frogs, Xenopus laevis and Xenopus borealis,which have mtDNAs that vary in many nucleotides. Thetechniques they used at the time were not sensitiveenough to detect small amounts of paternal DNA. Whattechniques that are highly sensitive to small amounts ofDNA could be used today? How could you use thesetechniques to determine if paternal mitochondrial DNAwas present in the progeny of the interspecies cross?
In Drosophila, the autosomal recessive dp allele ofthe dumpy gene produces short, curved wings, whilethe autosomal recessive allele bw of the brown genecauses brown eyes. In a testcross using femalesheterozygous for both of these genes, the followingresults were obtained:wild-type wings, wild-type eyes 178wild-type wings, brown eyes 185dumpy wings, wild-type eyes 172dumpy wings, brown eyes 181In a testcross using males heterozygous for both ofthese genes, a different set of results was obtained:wild-type wings, wild-type eyes 247dumpy wings, brown eyes 242a. What can you conclude from the first testcross?b. What can you conclude from the second testcross?c. How can you reconcile the data shown in parts (a)and (b)? Can you exploit the difference betweenthese two sets of data to devise a general test forsynteny in Drosophila?d. The genetic distance between dumpy and brown is91.5 m.u. How could this value be measured?
Human geneticists have found the Finnish populationto be very useful for studies of a variety of conditions.The population is small; Finns have extensive churchrecords documenting lineages; and few people havemigrated into Finland. The frequency of some recessive disorders is higher in the Finnish population thanelsewhere in the world, and diseases such as PKU andcystic fibrosis that are common elsewhere do not occur in the Finnish population.a. How would a population geneticist explain thesevariations in disease occurrence?b. The Finnish population is also a source ofinformation for the study of quantitative traits. Thegenetic basis of schizophrenia is one question that canbe explored in this population. What advantage(s) anddisadvantage(s) can you imagine for studying complex traits based on the Finnish population structure?
DNA (haplotypes) originating from the Denisovans can be found in the genomes of Indigenous Australians and Melanesian Islanders. However, thesame DNA markers are not found in the genomes of people native to Africa. Explain.
On average, what proportion of the genome in the following pairs ofhumans would be exactly the same if no crossing over took place? (Forthe purposes of this question only, we will ignore the special case of theX and Y sex chromosomes and assume that all genes are located onnonsex chromosomes.)a. Father and childb. Mother and childc. Two full siblings (offspring that have the same two biological parents)d. Half siblings (offspring that have only one biological parent incommon)e. Uncle and niecef. Grandparent and grandchild
. Consider the genotypes of two lines of chickens: thepure-line mottled Honduran is i/i ; D/D ; M/M ; W/W, andthe pure-line leghorn is I/I ; d/d ; m/m ; w/w, whereI = white feathers, i = colored feathersD = duplex comb, d = simplex combM = bearded, m = beardlessW = white skin, w = yellow skinThese four genes assort independently. Starting withthese two pure lines, what is the fastest and mostconvenient way of generating a pure line that has coloredfeathers, has a simplex comb, is beardless, and has yellowskin? Make sure that you showa. the breeding pedigree.b. the genotype of each animal represented.c. how many eggs to hatch in each cross, and why thisnumber.d. why your scheme is the fastest and the mostconvenient