Biol375 2016: Difference between revisions

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===Part 2. Trait & Sequence Evolution===
===Part 2. Trait & Sequence Evolution===
* 9/22 (Th).  Traits & trait matrix
{| class="wikitable sortable mw-collapsible"
|- style="background-color:lightsteelblue;"
! Assignment #4 (5 pts; Due Monday, 9/26)
|- style="background-color:white;"
|
# Download or Copy/Paste [http://media.hhmi.org/biointeractive/activities/lizard/Anolis-DNA-sequences.txt the lizard DNA sequences] to your own computer and save the file as "lizard.txt"
# Align the DNA sequences [http://www.phylogeny.fr/one_task.cgi?task_type=muscle using this website] and save the aligned DNA file ("Output->Alignment in Fasta format") as "lizard-aligned.txt" (No need to print or submit the above two DNA sequence files; save them for next week's assignment)
# Based on [http://media.hhmi.org/biointeractive/activities/lizard/Lizard-Cards-Color.pdf the lizard card], construct a character-state matrix for all lizard species. For each species, list its character state for each of the following two characters (as columns): (1) Geographic origin, and (2) Habitat. Re-watch [http://media.hhmi.org/biointeractive/films/OriginSpecies-Lizards.html the video] may help this assignment. '''Hint''': use Excel & hand in a printout of your Excel sheet.
|}
* 9/26 (M). Homoplasy & consistency
* 9/29 (Th). Parsimony reconstruction (Chapter 5). In-Class Exercise 4
{| class="wikitable sortable mw-collapsible"
|- style="background-color:lightsteelblue;"
! Assignment #5 (10 pts; Due 10/)
|- style="background-color:white;"
|
# Use the DNA alignment from the last assignment to build a tree of ''Anolis'' species.
## Set working directory to where you have downloaded the DNA alignment file: e.g., setwd("/Users/ann/Document")
## Load library: library(ape)
## Read alignment: aln.an = read.FASTA("lizard-aligned.txt")
## Calculate pairwise distance matrix: dist.an = dist.dna(aln.an)
## Estimate tree: tr.an = bionj(dist.an)
## Reroot tree: tr.root = root(tr.an, outgroup = "Leiocephalus_barahonensis", resolve.root = T)
## Save tree: write.tree(tr.root, "rerooted.dnd")
## Read re-rooted tree: tr.2 = read.tree("rerooted.dnd")
## Download [http://diverge.hunter.cuny.edu/w/images/2/21/Pheno.txt the phenotype file] and save it as "pheno.txt"
## Read phenotype with the command: ph = read.table("pheno.txt", row.names = 1)
## Assign column names: colnames(ph) = c("hab", "geo", "hab_id", "geo_id")
## Plot re-rooted tree: plot(tr.2, x.lim = 1, y.lim = 18, show.tip.label = F)
## Add species names: text(rep(0.2,17), 1:17, tr.2$tip.label, pos=4, font = 3)
## Match species names to tree order: ord = match(tr.2$tip.label, rownames(ph))
## Add a column: text(rep(0.5,17), 1:17, ph[ord,1], pos=4, col = ph[ord,3])
## Add another column: text(rep(0.7,17), 1:17, ph[ord,2], pos=4, col = ph[ord,4])
## Add a heading: text(0.5, 18, "Ecomorph", font = 2, pos=4)
## Add another heading: text(0.7, 18, "Geography", font = 2, pos=4)
## Export & print two copies (in color, preferably)
# On one copy, infer locations (i.e., islands) of all internal nodes using parsimony
# On another copy, infer habitats (i.e., ecomorphs) of all ancestors
# Based on your reconstructed trait evolution, count the number of character-state changes and calculate consistency index for each trait.
# Compare the two consistency indices & explain why the molecular phylogeny supports convergent adaptive evolution to habitats.
|}
* 10/3 (No class)
* 10/6 (TH). Genome & gene structure (Chapter 3)
* <font color="gray">10/12 (M). No Class</font>
* 10/10 (M).  Genome and gene evolution.
* 10/13 (Th). Review & Practices.
* 10/17 (M). '''Midterm Exam 2'''


===Part 3. Tree Algorithms===
===Part 3. Tree Algorithms===


===Part 4. Population Genetics ===
===Part 4. Population Genetics ===

Revision as of 16:01, 17 September 2016

Molecular Evolution (BIOL 375.00/790.64/793.03, Fall 2016)
Instructor: Dr Weigang Qiu, Associate Professor, Department of Biological Sciences
Room: 926 HN (Seminar Room, North Building)
Hours: Mon. & Thur 4:10-5:25 pm
Office Hours: Belfer Research Building (Google Map) BB-402; Wed 5-7 pm or by appointment
Course Website: http://diverge.hunter.cuny.edu/labwiki/Biol375_2016
Borreliabase-screenshot-1.png

Course Description

Molecular evolution is the study of the change of DNA and protein sequences through time. Theories and techniques of molecular evolution are widely used in species classification, biodiversity studies, comparative genomics, and molecular epidemiology. Contents of the course include:

  • Population genetics, which is a theoretical framework for understanding mechanisms of sequence evolution through mutation, recombination, gene duplication, genetic drift, and natural selection.
  • Molecular systematics, which introduces statistical models of sequence evolution and methods for reconstructing species phylogeny.
  • Bioinformatics, which provides hands-on training on data acquisition and the use of software tools for phylogenetic analyses.

This 3-credit course is designed for upper-level biology-major undergraduates. Hunter pre-requisites are BIOL203, and MATH150 or STAT113.

Please note that starting from fall 2015, completing this course no longer counts towards research credits for biology majors.

Textbooks

  • (Required) Graur, 2016, Molecular and Genome Evolution, First Edition, Sinauer Associates, Inc. ISBN: 978-1-60535-469-9. Publisher's Website (Student discount: a 15% discount and receive free UPS standard shipping)

http://www.sinauer.com/molecular-and-genome-evolution.html)

  • (Recommended) Baum & Smith, 2013. Tree Thinking: an Introduction to Phylogenetic Biology, Roberts & Company Publishers, Inc.

Learning Goals

  • Be able to describe evolutionary relationships using phylogenetic trees
  • Be able to use web-based as well as stand-alone software to infer phylogenetic trees
  • Understand mechanisms of DNA sequence evolution
  • Understand algorithms for building phylogenetic trees

Links for phylogenetic tools

Exams & Grading

  • Attendance (or a note in case of absence) is required. Bonus for active participation in classroom discussions.
  • Assignments. All assignments should be handed in as hard copies only. Email submission will not be accepted. Late submissions will receive 10% deduction (of the total grade) per day.
  • Three Mid-term Exams (30 pts each)
  • Comprehensive Final Exam (50 pts)

Academic Honesty

While students may work in groups and help each other for assignments, duplicated answers in assignments will be flagged and investigated as possible acts of academic dishonesty. To avoid being investigated as such, do NOT copy anyone else's work, or let others copy your work. At the least, rephrase using your own words. Note that the same rule applies regarding the use of textbook and online resources: copied sentences are not acceptable and will be considered plagiarism.

Hunter College regards acts of academic dishonesty (e.g., plagiarism, cheating on examinations, obtaining unfair advantage, and falsification of records and official documents) as serious offenses against the values of intellectual honesty. The College is committed to enforcing the CUNY Policy on Academic Integrity and will pursue cases of academic dishonesty according to the Hunter College Academic Integrity Procedures.

Course Schedule

Part 1. Tree Thinking

  • 8/25 (TH). Overview & Introduction. Textbook Chapter: "Introduction" (pages 1-3)
Assignment 1 (10 pts; Due: 8/29, Monday)
Pre-test: Full credits will be given as long as each question is answered with some reasoning. In other words, it will NOT be graded on being right or wrong. It's an assessment tool, to be compared with later test outcomes to show teaching/learning results.
File:Pretest.pdf
  • 8/29 (M). Introduction (Continued). Tutorial: R & R-Studio (Bring your own computer). Lecture slides:
    File:Intro.pdf
  • 9/1 (TH). Intro to trees. In-class exercise 1.
Assignment 2 (10 pts; Due: 9/8, Thursday)
Watch Origin of Species: Lizards in an Evolutionary Tree. Provide short answer (1-3 sentences) to each of the following three questions.
  1. What are the two hypotheses explaining the origin of different ecomorphs of lizards on Caribbean Islands?
  2. What is the expected phylogeny under each hypothesis?
  3. Which hypothesis is supported by the phylogeny of actual DNA sequences?
R exercises
  1. Install R & R-studio (see "Links for phylogenetic tools" above)
  2. Open R-studio and install the "ape" package using the "Packages"->"Install" menu, located within the lower right window
  3. Type in the console window (lower left) the following commands (one at a time, wait for the prompt ">" to appear before proceed to the next command; quit & restart R-studio if stuck):
    1. library(ape)
    2. tr = read.tree(text = "(monkey:0.09672,((tarsier:0.18996,lemur:0.14790)0.999:0.09005,(macaque:0.18524,(gibbon:0.10388,(orang-utan:0.09481,(human:0.03391,(gorilla:0.06135,chimpanzee:0.05141):0.01580)0.316:0.05381)1.000:0.03019)0.978:0.05616)0.997:0.05042)0.965:0.09672);")
    3. plot(tr)
  4. Export the tree graph using the "Export->Save as PDF or Save as Image" menu in the lower right window
  5. Exit R studio by typing the command "q()" and type "y" to answer the question for saving the R session
  6. Copy & paste the tree image into your document to be handed in
  • 9/5 (M). Labor Day. No class
  • 9/8 (TH). Intro to trees. In-class exercise 2. Textbook Chapter 5: "Molecular Phylogenetics" (pages 170-175; 201-202)
  • 9/12 (M). Species Tree & Lineage Sorting. Textbook Chapter 5: "Molecular Phylogenetics" (pages 177-180)
Assignment 3 (10 pts; Due: 9/19, Monday)
R exercises
  1. Download this file & save it in a file folder you could find (e.g., /Users/john/Documents/ for Apple, and C:/Users/john/Documents/ for Windows):
    File:Mt primate.txt
    . This is an alignment of mitochondrial DNA sequences from primate species, Do not attempt to open or modify it, which may render it un-readable by R. If this happens, delete & re-download.
  2. Open R-studio and install the "phangorn" package (see Assignment 2 for how to install packages)
  3. Run the following commands:
    1. getwd() (this is to show your working directory, from which R-studio could read file)
    2. setwd("/Users/john/Documents") (to set the working directory to where you saved your mt_primate.txt file)
    3. library(ape) (this is to load the ape library)
    4. mt = read.FASTA("mt_primate.txt") (to read the alignment and save it in an object called "mt")
    5. mt (to show result, copy & paste into your report)
    6. dist.mt = dist.dna(mt) (to obtain a pair-wise distance matrix)
    7. dist.raw = dist.dna(mt, model = "raw") (to obtain raw, un-corrected pair-wise sequence differences, in fractions)
    8. dist.raw * 888 (888 is the length of aligned DNA bases, to show raw counts of base differences; copy & paste into your report)
    9. tr.mt = bionj(dist.mt) ( to create a tree based on the pairwise distance matrix)
    10. plot(tr.mt) (to show tree; Export and save tree image)
    11. library(phangorn)
    12. tr.mid = midpoint(tr.mt) (this creates a midpoint-rooted tree)
    13. plot(tr.mid) (Export and save tree image)
    14. q() (to quit and save your R session, to your working directory)
  4. Answer the questions:
    1. Summarize, with your own complete sentences, the key steps you have taken to obtain a tree from sequences.
    2. Define "monophyly"
    3. Illustrating with your tree (by labeling ancestral nodes and groups of species), explain why "ape" excluding "human" does not constitute a monophyletic group.
  • 9/15 (TH). Consensus Tree & Review. Chapter 5. pages 199-200 (Figure 5.31) Lecture Slides:
    File:Part-1-tree-thinking-2016.pdf
  • 9/19 (M). 4:10 - 5:10pm Midterm Exam I Bring pencils, erasers, and a calculator

Part 2. Trait & Sequence Evolution

  • 9/22 (Th). Traits & trait matrix
Assignment #4 (5 pts; Due Monday, 9/26)
  1. Download or Copy/Paste the lizard DNA sequences to your own computer and save the file as "lizard.txt"
  2. Align the DNA sequences using this website and save the aligned DNA file ("Output->Alignment in Fasta format") as "lizard-aligned.txt" (No need to print or submit the above two DNA sequence files; save them for next week's assignment)
  3. Based on the lizard card, construct a character-state matrix for all lizard species. For each species, list its character state for each of the following two characters (as columns): (1) Geographic origin, and (2) Habitat. Re-watch the video may help this assignment. Hint: use Excel & hand in a printout of your Excel sheet.
  • 9/26 (M). Homoplasy & consistency
  • 9/29 (Th). Parsimony reconstruction (Chapter 5). In-Class Exercise 4
Assignment #5 (10 pts; Due 10/)
  1. Use the DNA alignment from the last assignment to build a tree of Anolis species.
    1. Set working directory to where you have downloaded the DNA alignment file: e.g., setwd("/Users/ann/Document")
    2. Load library: library(ape)
    3. Read alignment: aln.an = read.FASTA("lizard-aligned.txt")
    4. Calculate pairwise distance matrix: dist.an = dist.dna(aln.an)
    5. Estimate tree: tr.an = bionj(dist.an)
    6. Reroot tree: tr.root = root(tr.an, outgroup = "Leiocephalus_barahonensis", resolve.root = T)
    7. Save tree: write.tree(tr.root, "rerooted.dnd")
    8. Read re-rooted tree: tr.2 = read.tree("rerooted.dnd")
    9. Download the phenotype file and save it as "pheno.txt"
    10. Read phenotype with the command: ph = read.table("pheno.txt", row.names = 1)
    11. Assign column names: colnames(ph) = c("hab", "geo", "hab_id", "geo_id")
    12. Plot re-rooted tree: plot(tr.2, x.lim = 1, y.lim = 18, show.tip.label = F)
    13. Add species names: text(rep(0.2,17), 1:17, tr.2$tip.label, pos=4, font = 3)
    14. Match species names to tree order: ord = match(tr.2$tip.label, rownames(ph))
    15. Add a column: text(rep(0.5,17), 1:17, ph[ord,1], pos=4, col = ph[ord,3])
    16. Add another column: text(rep(0.7,17), 1:17, ph[ord,2], pos=4, col = ph[ord,4])
    17. Add a heading: text(0.5, 18, "Ecomorph", font = 2, pos=4)
    18. Add another heading: text(0.7, 18, "Geography", font = 2, pos=4)
    19. Export & print two copies (in color, preferably)
  2. On one copy, infer locations (i.e., islands) of all internal nodes using parsimony
  3. On another copy, infer habitats (i.e., ecomorphs) of all ancestors
  4. Based on your reconstructed trait evolution, count the number of character-state changes and calculate consistency index for each trait.
  5. Compare the two consistency indices & explain why the molecular phylogeny supports convergent adaptive evolution to habitats.
  • 10/3 (No class)
  • 10/6 (TH). Genome & gene structure (Chapter 3)
  • 10/12 (M). No Class
  • 10/10 (M). Genome and gene evolution.
  • 10/13 (Th). Review & Practices.
  • 10/17 (M). Midterm Exam 2

Part 3. Tree Algorithms

Part 4. Population Genetics

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