Population-Level Information and Chi-Squared Testing - Vocabulary

Vocabulary flashcards covering key concepts about information at the population level, types of communication and signals (including quorum sensing and VOCs), as well as Chi-squared statistics and hypothesis testing from the lecture notes.

Heritable information

Genetic information passed from parents to offspring; includes physical traits, inherited behaviors, and the ability to communicate.

Non-heritable information

Information exchanged between individuals that is not genetically inherited; arises from environment, experience, behaviors, and learning.

Population-level information

Information that exists within a population, arising from both heritable and non-heritable sources to support species continuity.

Categories of communication

Finding a mate, Defense, Facilitate cooperation, and Warning; each category has associated costs and benefits.

Quorum sensing

A density-dependent communication mechanism in bacteria where cells coordinate behavior after a threshold concentration of signaling molecules is reached.

Volatile Organic Compounds (VOCs)

Chemical signals released by plants that convey information to other plants or parts of the same plant, triggering defense responses.

Specialist defense (in VOC signaling)

A plant defense response triggered by VOCs from family members, leading to specific defense preparations.

General defense (in VOC signaling)

A broader plant defense response triggered by VOCs from non-family sources, protecting against a range of herbivores.

Imperfect communication

Non-perfect information exchange that introduces variation in the information available within a population.

Null hypothesis

A baseline statement of no effect or no difference used to compare observed data.

Observed frequencies (O)

The actual counts recorded in data.

Expected frequencies (E)

The counts expected under the null hypothesis.

Chi-squared statistic (X²)

X² = sum[(O − E)² / E] across categories; used to test how well observed data fit the null hypothesis.

Degrees of freedom (df)

Number of independent categories minus one; for chi-squared tests, df = number of classes − 1.

Significance level (p = 0.05)

The threshold probability below which results are considered statistically significant in biology.

Critical chi-squared value

The value from the chi-squared distribution table at a given df and p-level; compare this to the calculated X².

Chi-squared test decision rule

Reject the null hypothesis if the calculated X² is greater than the critical value; otherwise fail to reject.

Null hypothesis example (call-response study)

In the storm petrel study, the null hypothesizes that the proportion of calls is equal across different situations.

Hypothesis about behavior

A statement about what triggers a behavior and what is adaptive about it.

Variation in information

Differences in information available to individuals due to imperfect communication within a population.