Biol375 2016

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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
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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) Roderic M. Page and Edward C. Holmes,1998, Molecular Evolution: A phylogenetic Approach, Blackwell Science Ltd.
  • (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

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). 1.1. Introduction (Continued). In-class exercise 1. Tutorial: R & R-Studio (Bring your own computer)
  • 9/1 (TH). 2.1. Intro to trees
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). 2.2 & 2.3. Tree Distance. In-class exercise 2.
    File:In-class-2.pdf
Assignment 3 (10 pts; Due: 9/15, Th)
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.
  • 9/12 (M). 2.4 & 2.5. Species Tree & Lineage Sorting
  • 9/15 (TH). 2.5. Consensus Tree & Review. Chapter 2 Slides:File:Part-1-tree-thinking.pdf. In-class Exercise 3:
    File:In-class-3.pdf
  • 9/19 (M). 4:10 - 5:10pm Midterm Exam I Bring pencils, erasers, and a calculator

Part 2. Trait Evolution

Part 3. Tree Algorithms

Part 4. Population Genetics

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