Which part of the living system did you change?
Labs / Biology
Genetic Drift
Each colored line is one isolated population passing an allele down the generations by random sampling — no selection, no migration, just luck. Shrink the populations and watch how quickly chance alone pushes some to fixation and others to loss, dragging the average heterozygosity (the dashed line) toward zero.
Labs / Biology / Genetic Drift
Genetic Drift
Each colored line is one isolated population passing an allele down the generations by random sampling — no selection, no migration, just luck. Shrink the populations and watch how quickly chance alone pushes some to fixation and others to loss, dragging the average heterozygosity (the dashed line) toward zero.
Why it matters
Why explore this?
Living systems are connected and constantly changing. This model makes one biological process visible so you can test how its parts affect one another.
Explore
Try the model
gen 0fixed 0/12lost 0/12H̄ 0.500
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
What to try
- Drop the population size to 5. How many generations pass before most lines slam into fixation or loss?
- Crank the population size up to 400. Why do the lines suddenly stay huddled near the middle?
- Start at frequency 0.1 — are populations more likely to fix the allele or lose it, and why?
- With 24 parallel populations at 0.5, roughly what fraction end up fixed versus lost once they all settle?
- Watch the dashed mean-heterozygosity line: does small versus large population size change how fast diversity drains away?
Explain
Make sense of what happened
Explain the process as a chain: a change happens, the system responds, and that response affects what happens next. Use an observation from the model as evidence.
Check
Before you leave
How did the system respond?
How would you explain that response?
If you can answer all three using evidence from the model, you understand the main idea. If not, return to Explore and change one setting at a time.