LSM2107: pass the exams, not just read the notes
Your complete guide to National University of Singapore's evolutionary biology course. See where the marks are, work real practice questions, and study with an AI tutor that knows LSM2107.
Sia generates LSM2107 practice questions, walks through what is evolution and how did life evolve step by step, and quizzes you on the material the exam weights most heavily.
Worked example
Two bird species on separate islands independently evolve long, thin bills for probing flowers. Their most recent common ancestor had a short, stout bill. Is this homology or convergence, and how would a phylogeny reveal it?
Distinguish the two possibilities. Homologous traits are shared through inheritance from a common ancestor; convergent traits are independently derived because similar selection produced similar solutions in separate lineages.
Map the trait onto the tree. Present at both tips, absent at the shared node, means the trait must have originated twice — two independent gains rather than one inherited state. That is the formal signature of convergence.
Note why the phylogeny is essential. Morphology alone cannot distinguish the two cases, because homologous and convergent traits can look identical. This is exactly why the course lists reconstructing relationships and interpreting phylogenies as a learning outcome.
The trap: Option B — inferring shared ancestry from shared appearance — is the classic error, and it is the reason phylogenetic method exists. Option C is subtler and just as wrong: it reaches the right answer by the wrong route, since without an ancestral state there is no way to tell convergence from homology. Option D misapplies coevolution, which describes reciprocal evolutionary change between interacting lineages; a bird-flower interaction could involve coevolution, but that is a separate question from whether the two birds' bills are homologous. classic slip!
One exam decides 30% of your grade. Summative. This whole page is built around that.
Overview
What LSM2107 is, and where it sits
LSM2107 covers, in the words of the official description, the history of life on our planet and the processes that produced the multiple life forms of Earth. The named topics run from the origins of life, the eukaryotic cell and multicellularity, through the generation of genetic variation and its sorting by random processes and by natural and sexual selection, to the origin of new traits, life histories and species, the origins of sex, sociality and altruism, the evolution of humans, and applications of evolutionary biology to modern problems.
The published syllabus is structured unusually: every one of the thirteen weeks is framed as a question. What is the evidence for evolution? How do variations get fixed in populations? What are species and how does speciation occur? Why sex? How does altruism evolve? That framing is not decoration — it signals that the course assesses explanation rather than recall, and the learning outcomes confirm it, asking students to reconstruct evolutionary relationships, estimate genetic and environmental components of variation, and apply evolutionary concepts to real-world challenges.
Assessment is spread across five components: 5% class participation, 15% quizzes, a 30% mid-term test, 20% assignments and a 30% final examination. Sixty percent of the grade sits in two timed sittings, so the course rewards steady conceptual work rather than either pure cramming or pure coursework.
Official outline: dbs.nus.edu.sg · LSM2107 outline. Always treat the official outline and the exam timetable as authoritative.
Difficulty & time commitment
Is LSM2107 hard, and how much time does it take?
LSM2107 is manageable if you keep a weekly rhythm and treat the back half as the main event. The pattern is consistent: it starts gently and steepens, and the heaviest assessment is the part that separates grades.
The difficulty curve and the assessment weighting point the same way: the back half is harder and worth more. Front-loading effort there is the highest-return decision in the course.
Is this course for you
Who tends to do well, and who tends to struggle
You will likely do well if
- You can answer each week's question in your own words with a mechanism attached, which is exactly how the course is framed.
- You practise reading phylogenies until mapping a trait onto a tree is automatic.
- You prepare for the mid-term as seriously as the final; they carry identical weight.
- You are comfortable with population-level reasoning about frequencies rather than individuals.
You may struggle if
- You infer common ancestry from similar appearance, which phylogenetic method exists to prevent.
- You treat evolution as a narrative of progress rather than a process of differential reproduction.
- You underestimate the mid-term because it arrives before the material feels consolidated.
- You skip the counterintuitive material — why sex, how altruism evolves — because it resists common sense.
- Write your own one-paragraph answer to each of the thirteen weekly questions. That set of answers is the course.
- Drill trait mapping on trees: given tips and an ancestral state, decide homology or convergence in seconds.
- For every mechanism — drift, selection, sexual selection, kin selection — be able to say what it predicts and what would falsify it.
- Use the applied examples from the learning outcomes, such as host-parasite coevolution in disease management, as ready-made evidence in written answers.
Syllabus
The 13 topics, week by week
The exam-weight marker on each topic shows where the marks concentrate. The amber topics carry the highest exam weight.
W1 · What is evolution, and what is the evidence for it?
Official DBS syllabus, Week 1Defining evolution and assembling the evidence that supports it.
W2 · How did life evolve, and how do variations arise?
Official DBS syllabus, Week 2The origins of life and the sources of heritable variation.
W3 · How do variations get fixed: drift and natural selection
Official DBS syllabus, Week 3Fixation through random processes, and fixation through natural selection.
W4 · Outcomes of natural selection, and artificial selection
Official DBS syllabus, Week 4What selection produces, and how humans apply it deliberately.
W5 · Life histories and environmental determination of phenotype
Official DBS syllabus, Week 5How evolution shapes life history strategies, and how environment shapes phenotype.
W6 · Genotype to phenotype, and major transitions
Official DBS syllabus, Week 6Connecting genotype to phenotype, and the major transitions in evolution.
W7 · Reconstructing relationships and reading phylogenies
Official DBS syllabus, Week 7How species relationships are inferred, and how to interpret a phylogenetic tree.
W8 · What are species, and how does speciation occur?
Official DBS syllabus, Week 8Species concepts and the mechanisms that generate new species.
W9 · Why sex? Sexual selection
Official DBS syllabus, Week 9The evolutionary puzzle of sexual reproduction, and selection through mate choice and competition.
W10 · Evolutionary genomics and evo-devo
Official DBS syllabus, Week 10Genomic approaches to evolution, and how developmental change originates novel traits.
W11 · Coevolution and convergent evolution
Official DBS syllabus, Week 11Reciprocal evolutionary change between lineages, and independent arrival at similar solutions.
W12 · Sociality, altruism and human evolution
Official DBS syllabus, Week 12How cooperation and altruism evolve, and the evolutionary history of humans.
W13 · How evolution affects our lives
Official DBS syllabus, Week 13Applications of evolutionary biology to present-day problems.
How it's assessed
Assessment structure
| Component | Weight | Format & timing |
|---|---|---|
| Mid-term test | 30% | Timed mid-term test. Mid-semester. Summative. |
| Final examination | 30% | Final examination. NUS examination period. Summative. |
| Assignments | 20% | Assignments across the semester, published in the official listing as a named continual assessment component. Across the semester. Continual assessment. |
| Quizzes and tests | 15% | Quizzes and tests across the semester. Across the semester. Continual assessment. |
| Class participation | 5% | Participation in class. Across the semester. Continual assessment. |
- The five components sum to 100. No separate component hurdle is published.
- Two equally weighted timed assessments carry 60% between them, so the mid-term is as consequential as the final. The remaining 40% is spread across assignments, quizzes and participation, which means falling behind early is costly in both directions.
This is an exam-cram course. With the exams at 60% of the grade and the mid-term test alone at 30%, your result is overwhelmingly decided by how well you perform under time pressure. Summative.
Final exam timing: During the NUS examination period. Confirm the exact date and venue on the official exam timetable.
How to actually pass it
A weekly rhythm, two checklists, and the traps to avoid
The course rewards consistency over cramming, and practice over re-reading. Here is the loop that works, then what to have nailed before each exam.
The weekly loop
Before the mid-semester checklist
- State what evolution is and assemble the evidence for it.
- Explain the origins of life and the sources of heritable variation.
- Distinguish fixation by drift from fixation by natural selection.
- Explain the outcomes of natural selection and how artificial selection is applied.
Before the final heaviest topics
- Reconstruct evolutionary relationships and interpret phylogenies, distinguishing homology from convergence.
- Explain species concepts and the mechanisms of speciation.
- Account for the evolution of sex and the operation of sexual selection.
- Explain how sociality and altruism evolve, and apply evolutionary concepts to real-world challenges.
The mistakes that cost marks
Similarity read as shared ancestry. Convergent traits look homologous. Only an ancestral state on a phylogeny distinguishes them, which is why tree reading is a stated learning outcome.
Evolution as progress. Selection produces fit to current conditions, not advancement. Framing answers as improvement over time misstates the mechanism.
Confusing drift with selection. Drift fixes variants by chance and matters most in small populations; selection fixes them by differential reproduction. The course tests which applies where.
Group-benefit explanations of altruism. Saying a behaviour evolved 'for the good of the species' skips the actual mechanisms — kin selection, reciprocity — that the course requires.
Teaching team
Who teaches LSM2107
The bios below are factual. We do not rate lecturers; any star ratings are submitted by students who have taken LSM2107.
Dr Nalini Puniamoorthy
Assoc Prof John Ascher
Teaching team as listed in the course materials reviewed. AskSia does not rate lecturers; star ratings are submitted by students who have taken LSM2107.
Formula & concept sheet
The vocabulary and formulas you must own
- Genetic drift
- Change in allele frequency due to random sampling across generations; its effect is strongest in small populations.
- Natural selection
- Differential survival and reproduction of heritable variants, producing adaptation to current conditions.
- Sexual selection
- Selection arising from competition for mates and mate choice, which can favour traits that reduce survival.
- Fixation
- The point at which an allele reaches a frequency of one in a population, all alternatives having been lost.
- Linkage disequilibrium
- Non-random association between alleles at different loci, informative about selection and population history.
- Phylogeny
- A branching hypothesis of evolutionary relationships, on which traits can be mapped to infer their history.
- Homology
- Similarity due to inheritance from a common ancestor.
- Convergent evolution
- Independent evolution of similar traits in separate lineages under similar selection; identifiable only against a phylogeny.
- Coevolution
- Reciprocal evolutionary change between interacting lineages, such as host and parasite.
- Speciation
- The process by which one lineage splits into two that no longer exchange genes.
- Life history
- The schedule of growth, reproduction and survival that evolution shapes as a strategy under trade-offs.
- Kin selection
- Selection favouring behaviour that lowers an individual's own reproduction while raising that of relatives sharing its alleles.
Common acronyms: LD · MRCA.
Where it fits
Prerequisites, related courses & why it matters
Entry requirement published by NUS: GCE A-Level or H2 Biology or equivalent, or LSM1301 General Biology. The course is worth 4 units, runs in both semesters, and is a prerequisite for LSM3252 Evolution and Comparative Genomics.
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FAQ
Frequently asked questions
Is LSM2107 hard?
It rates moderately hard. The concepts are approachable but the course is question-driven and expects explanation rather than recall, and 60% of the grade sits in a mid-term and a final of equal weight.
What is the assessment breakdown?
30% mid-term test, 30% final examination, 20% assignments, 15% quizzes and tests, and 5% class participation. The mid-term matters exactly as much as the final.
What do I need before taking it?
GCE A-Level or H2 Biology or an equivalent, or LSM1301 General Biology.
Who teaches it?
The published course coordinators are Dr Nalini Puniamoorthy in Semester 1 and Assoc Prof John Ascher in Semester 2.
How much mathematics is there?
Enough to matter. Population genetics, linkage disequilibrium and separating genetic from environmental components of variation are all examinable, but the mathematics stays at the level of algebra and proportions.
What is the hardest part?
For most students it is phylogenetics — reading trees correctly and distinguishing homology from convergence — followed by the conceptual puzzles around why sex and how altruism can evolve, both of which resist intuition.
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Work through what is evolution, how did life evolve, how do variations get fixed: drift and the rest of the course with a tutor that knows it and quizzes you on the topics the assessments weight most heavily.
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