biology

Weak evolutionarily stable strategy

Weak evolutionarily stable strategy is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Weak evolutionarily stable strategy rather than just read about it. In short: A weak evolutionarily stable strategy (WESS) is a more broad form of evolutionarily stable strategy (ESS). Like ESS, a WESS is able to defend against an invading "mutant" strategy.

Key takeaways

Weak evolutionarily stable strategy belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Weak evolutionarily stable strategy to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Weak evolutionarily stable strategy from memory before moving on to harder problems.

Reference excerpt

A weak evolutionarily stable strategy (WESS) is a more broad form of evolutionarily stable strategy (ESS). Like ESS, a WESS is able to defend against an invading "mutant" strategy. This means the WESS cannot be entirely eliminated from the population. The definition of WESS is similar to ESS. Any strategy s is a weakly evolutionarily stable strategy (WESS) if for any strategy s*≠s: (i) u(s, s) > u(s*, s) or (ii) u(s, s) = u(s*, s) and u(s, s*) ≥ u(s*, s*). One example of WESS, in a prisoner's dilemma, is Tit-for-tat (a strategy that cooperates in the first interaction and then reciprocates the other player's action from the previous turn in all other iterations).

References

Worked examples

Example 1 — a first encounter with Weak evolutionarily stable strategy

Start with the simplest possible case. Write down what Weak evolutionarily stable strategy claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Weak evolutionarily stable strategy before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Weak evolutionarily stable strategy ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Weak evolutionarily stable strategy

In research: Weak evolutionarily stable strategy appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Weak evolutionarily stable strategy in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Weak evolutionarily stable strategy is common in secondary-school and first-year university syllabi. It links to neighbouring topics Evolutionary game theory, so understanding it makes those chapters shorter.
In everyday life: Look for Weak evolutionarily stable strategy outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Weak evolutionarily stable strategy in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Weak evolutionarily stable strategy means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Weak evolutionarily stable strategy out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Weak evolutionarily stable strategy in simple terms?

A weak evolutionarily stable strategy (WESS) is a more broad form of evolutionarily stable strategy (ESS). Like ESS, a WESS is able to defend against an invading "mutant" strategy.

Why does Weak evolutionarily stable strategy matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Weak evolutionarily stable strategy?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Weak evolutionarily stable strategy.