Evolution Final Exam Review

Content: Human Evolution and ...

Fill in the blank:

Genomic evidence reveals that humans are members of the primate superfamily known as the ___, or the apes. This does not mean that humans evolved from monkeys, we did not.  We know this because monkeys still exist today. Humans do share a common ancestor with monkeys.

Hominoidea

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Among living species, ___ are most closely related to humans. Again, humans did not evolve from ___, because ___ still exist. We share a most recent common ancestor (MRCA) with ___.

chimps

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The hominin clade includes both humans and extinct species more closely related to humans than to chimps. Hominins are distinguished by a reduction of the ___ and ___ and by adaptations for ___ ___. This clade is not a single linear progression of species, but rather a branching tree with multiple and diverse hominin species coexisting for most of its evolutionary history.

jaw, teeth, bipeadal locomotion

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Some time after 2.4 million years ago, the first members of the genus Homo arose from archaic hominin ancestors. These species had larger ___ than previous hominins. They were followed by the premodern hominins, including Homo erectus, with yet greater ___ ___ and longer ___.

brains, cranial capacity, limbs

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The out-of-Africa hypothesis posits multiple hominin radiations out of Africa. Under this hypothesis, modern Homo sapiens evolved in Africa less than ___ years ago, migrated beyond Africa around ___ years ago, and replaced other hominins around the globe by ___ years ago. Fossil evidence, archaeological evidence, and mitochondrial DNA sequence data all support the out-of-Africa model.

200,000 / 60,000 / 30,000

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The out-of-Africa hypothesis posits multiple hominin radiations out of Africa. Under this hypothesis, modern Homo sapiens evolved in Africa less than 200,000 years ago, migrated beyond Africa around 60,000 years ago, and replaced other hominins around the globe by 30,000 years ago. ___ evidence, ___ evidence, and ___ ___ sequence data all support the out-of-Africa model.

Fossil, archaeological, mitochondrial DNA

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After migrating out of Africa, modern Homo sapiens interbred with at least two other Homo lineages, the ___ and the ___. Today, humans originating from populations ___ of Africa carry a small amount of DNA from these other Homo groups.

Neanderthals, Denisovans, outside

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The majority of variation between human individuals is within-population variation: On average the genetic differences between individuals of ___ ancestral origins are only ___ ___ than the genetic differences between individuals with the ___ ancestral origin.

different, slightly greater, same

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By working with large numbers of loci simultaneously, researchers can use advances in ___ ___ and ___ ___ to infer the ancestral origin of individuals and reconstruct the historical relationships among ancestral groups. Analyses of this nature help us sketch out a story of ___ ___ around the globe, although there are limitations.

genetic sequencing, phylogenetic inference, human migrations

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The genetic history of certain ___, particularly those that are ___ transmitted from parents to offspring or shared primarily within families, reflects the ___ ___ of human populations and can be used to learn more about our evolutionary past.

pathogens, vertically, genetic history

Name the matrilineal most recent common ancestor (MRCA) of all living humans.

Mitochondrial Eve

What is the term for the formation of a new hybrid population from the interbreeding of two or more previously isolated ancestral populations?

Admixture

Provide the term for the definition given:

An evolutionary phenomenon where ancestral genetic polymorphisms (alleles) persist through rapid speciation events, causing gene trees to differ from the actual species tree.

Incomplete lineage sorting or deep coalescence

What taxonomic group refers to all apes including humans?

Hominoids

What taxonomic group refers to a subset of hominoids leading directly to modern humans?

Hominins

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Definitively determining the evolutionary relationship between humans, chimpanzees, and gorillas using a single locus (such as mitochondrial DNA) is difficult because individual gene trees often ___ with the actual species tree. This happens primarily due to a phenomenon called ___, which is particularly common in these species because their ancestors diverged in rapid succession, allowing ancestral genetic variation to be distributed randomly among the modern species.

conflict, incomplete lineage sorting (ILS)

True or False:

Mitochondrial Eve being a, say, 200,000-year-old African hominin directly supports the out-of-Africa hypothesis over the multiregional model by providing a single, recent common ancestor. This points to a new species arising in one location, rather than simultaneous, parallel evolution across the globe.

True

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The fact that specific individuals share ___ genetic similarity at certain loci with Neanderthals than with other modern humans is not, on its own, definitive proof of ___ because of the significant impact of ancestral population structure (from shared ancestory, and not necessarily interbreeding) and ___ ___.

higher, interbreeding, genetic drift

What proves interbreeding between modern humans and Neanderthals?

Hint: the large size and unbroken nature of shared DNA segments, which suggest recent introgression rather than shared ancestral lineage hundreds of thousands of years ago.

linkage disequilibrium

True or False:

A phylogeny created using the mitochondrial genome (mtDNA) is only a partially accurate reflection of human population relationships because it represents only a single matrilineal line rather than the full, complex ancestry of a population. Because mtDNA does not undergo recombination and is inherited only from the mother, it provides a very limited, often biased perspective that can clash with the more accurate picture provided by the nuclear genome.

True

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Human genetic diversity decreases with distance from Africa primarily due to a series of ___ during the prehistoric migration of modern humans out of Africa around 60,000–90,000 years ago. As small subsets of populations moved further away, they carried only a portion of the genetic variation from their parent population, resulting in lower diversity.

serial founder effects

Why is Helicobacter pylori a particularly useful bacterial species for inferring the population structure of its human hosts?

Vertical transmission and coevolution

Only when extensive genetic data became available were scientists able to definitively resolve the relationship between humans, chimps, and gorillas. Why it was a particularly difficult challenge to find the relationship between these three species?

Incomplete Lineage Sorting (ILS)

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The speculation that modern technology has brought human evolution to a halt is ___ because, while technology has altered the ___ of natural selection, it has not stopped it.

incorrect, pressures