Imagine that you have the DNA sequences from the intron of a gene in three species called A, B, and C. Species A and B are most closely related, while C is more distantly related. The sequences of A and B differ by 18 base pairs, A and C differ by 26 base pairs, and B and C differ by 28 base pairs. Fossils show that species A and B diverged about 1.2 Mya, but there is no fossil evidence as to when the most recent common ancestor of all three species lived. (Draw a simple tree to help you think about the problem) Use the genetic data to estimate that date (most recent common ancestor). What assumptions are you making to get this estimate?

Imagine that you have the DNA sequences from the intron of a gene in three species called A, B, and C. Species A and B are most closely related, while C is more distantly related. The sequences of A and B differ by 18 base pairs, A and C differ by 26 base pairs, and B and C differ by 28 base pairs. Fossils show that species A and B diverged about 1.2 Mya, but there is no fossil evidence as to when the most recent common ancestor of all three species lived. (Draw a simple tree to help you think about the problem) Use the genetic data to estimate that date (most recent common ancestor). What assumptions are you making to get this estimate?

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter32: Deuterostomes: Vertebrates And Their Closest Relatives

Section: Chapter Questions

Problem 1ITD: The phylogenetic tree for vertebrates depicted below was constructed from sequence data for two rRNA...

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Species A and B have long wings, whereas species C has short wings. Which of the following pieces of evidence would best support the hypothesis that long wings are a synapomorphy? A. DNA evidence showing that species B and C are sister species B. Fossil evidence showing that the common ancestor of species A, B, and C had short wings C. DNA evidence showing that species A and C are sister species D. Fossil evidence showing that the common ancestor of species A, B, and C had long wings E. Evidence showing that species A and B live in an environment that favors long wings, whereas species C lives in an environment that favors short wings
The phylogenetic tree for vertebrates depicted below was constructed from sequence data for two rRNA mitochondrial genes (12S and 16S). How do the results of this analysis compare with the phylogenetic trees in Figures 32.10 and 32.24? Identify the major clades of vertebrates on the tree depicted below. Source: R. Zardoya and A. Meyer. 1998. Complete mitochondrial genome suggests diapsid affinities of turtles. Proceedings of the National Academy of Sciences, USA 95:1422614231. Copyright 1998 National Academy of Sciences, U.S.A.
When I first studied hominin evolution, they had found "Lucy", an Australopithecus afarensis, and everyone thought her species was an early ancestor of Homo sapien. The picture is much more complicated, with lots of hominins living in close proximity for millions of years...much different than our now singular species. Look at the phylogenetic tree and use it as a guide to briefly describe hominin lines in Africa up to Homo. Do not discuss Homo.Just discuss a sense that you generally can grasp what was going on in Africa with our Genus for 6 or 7 million years!
A researcher studying two species (species 1 and species 2) sequences a short stretch of eight codons from the same gene, gene B, in each and compares them. Species 1 and species 2 had a most recent common ancestor 50 million years ago. Species 1: ATC GGG CGG GAC TTA CTA TAT GCC Species 2: ATT GGG CGG GAC TTG CTA TAT GCC Given the differences between the sequences of the two species' genes shown here, what evolutionary force can you predict is most likely in operation on gene B?
Imagine that you have the DNA sequences fromthe intron of a gene in three species called A, B,and C. Species A and B are most closely related,while C is more distantly related. The sequencesof A and B differ by 18 base pairs, A and C differby 26 base pairs, and B and C differ by 28 basepairs. Fossils show that species A and B divergedabout 1.2 Mya, but there is no fossil evidence asto when the most recent common ancestor ofall three species lived. Use the genetic data toestimate that date. What assumptions are youmaking to get this estimate?
Why is molecular data for phylogenetic inference best analyzed with use of an explicit model of molecular evolution? A) This is true of morphological data, not molecular data, it is impossible to model changes in molecular sequence data because it is constantly evolving. B) Because molecular data is known to only experience random changes and is constantly evolving, a chaotic model of evolution can universally be applied to molecular sequence data for phylogenetic analysis. C) Because molecular data is known to experience non-random changes in terms of the likelihood of different types of mutations -- transitions vs. transversions, at different codon positions, which can be used to infer sequence evolution and relationship. D) None of the above.
Suppose we are sure, because of previous studies, that species 1, 2, and 3 are more closely related to each other than to species 4 (outgroup). We sequence a gene and find ten nucleotide sites that differ among the four species. Draw the most parsimonious tree and label each evolutionary change on the tree (Position – new nucleotide; Example = 8T or 6C). *The answer is below but I do not understand where the numbers or tick marks came from? Could someone explain. For example, why is the 1A on the 2?
Which of the following statements best explains the importance of sister taxa for understanding the evolution of ingroup taxa? A) The sister group informs of the likely state of the common ancestor of the ingroup. B) The sister group is composed only of ancestral characters representing a primitive taxon having ancestral states for all characters able to be studied. C) The sister group allows us to infer character state polarity in order to understand how character states have changed during evolution of the ingroup. D) A & B E) A& C F) All of the above.
If mutations such as those of the Ubx gene can drastically change morphology in a single step, why do most evolutionary biologists maintain that modification of existingtraits and the evolution of novel characters have generally proceeded by successive small steps?
A cladogram used in a comparison of morphology among taxa had equal length branches, but when looked at in a blast webpage using the given gene sequence, the branches all had different lengths. Why is that?
In the past, the evolutionary history of whales was represented by cladogram A, shown below. As you can see, whales were believed to be closely related to mesonychids, an extinct group of mammals that looked similar to wolves. Today, that cladogram has been revised, as shown in cladogram B. Which of the following statements best describes the reason for this change? A - Cladograms A and B are hypotheses that changed as new evidence became available.B - Cladogram B was revised to show a water-to-land pattern of evolution in groups of organisms.C - Cladogram B was altered to better include similarities in habitat as new information became available.D - Cladograms are organized today to show a much more simplified pattern like the one shown in cladogram B.
By comparing DNA sequence of a specific gene, we can determine the evolutionary relationship of two organisms. Based on the sequence listed below, which two species would you expect to be more closely related? Organism No.1 with ATG CAA TAC GCC, organism No. 2 with ATG CAT GAC ACC and organims No. 3 with ATG CAT TAC GCC A. Organims No.2 and No.3 are likely more closely related. b.Organims No.1 and No.2 are likely more closely related. c.Organims No 1 and No.3 are likely more closely related.