Summary
Variation in a population is the raw material on which natural selection works. How do scientists measure and quantify variation in traits? We use garden snails as a model organism in order to describe and measure several different traits. Groups are given a small population of snails and must devise an objective way to measure a trait of their choosing (length, mass, speed, color intensity, stripes, withdrawal reflex reaction time, number of pennies it can carry, etc.). There are many ways to extend this activity. For instance, scientific protocols may be traded between groups, hypotheses may be made concerning what individuals will survive better in different environments, and snails may be tagged and released into one or more environments and the populations monitored over time. A long term open-ended project such as this provides a natural extension and assessment opportunity for both evolution and ecology concepts.
Objectives
Can make observations in an objective, quantifiable manner.
Can select and use tools to collect data.
Can use tables and graphs to represent data and identify patterns in data.
Can describe the role of variation in a population in natural selection and evolution.
Vocabulary
Traits
Variation
Population
Natural selection
Evolution
Objective
Subjective
Quantify
Histogram
