lesson
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If a single pair of mice had unlimited food and zero predators, their descendants would number in the millions in just a few years. Yet in the wild, mouse populations stay roughly constant.
In 1859, Charles Darwin and Alfred Russel Wallace proposed a mechanism to explain why only a tiny fraction survive and how living things change over time: natural selection.
How does nature decide which individuals survive to shape future generations?
Step 1: Genetic Variation
Within every population, individuals show genetic variation caused by random mutations that generate different alleles (alternative versions of a gene).
📊Create an interactive visual flow diagram representing the 5 stages of Natural Selection in a clean vertical layout (cards connected by animated downward arrows). Card 1: '1. Genetic Variation' (icons showing DNA mutations giving mice brown vs white fur). Card 2: '2. Overproduction' (many baby mice born). Card 3: '3. Competition' (hawk predator and scarce grain icons). Card 4: '4. Differential Survival' (camouflaged brown mouse survives, white mouse caught). Card 5: '5. Inheritance & Evolution' (brown mice reproduce, allele frequency increases). Responsive width (max 380px), color palette: dark slate text (#1e2945), soft off-white background (#f8fafc), teal borders/accents (#0d9488), smooth subtle hover animations.
What happens when too many individuals must share the same finite space and food?
Overproduction and Competition
Organisms produce more offspring than the environment can support, which inevitably leads to a struggle for survival.
This struggle creates selection pressures — environmental factors like predators, disease, or scarce food that make survival challenging for less well-adapted organisms.
📊A visual diagram showing a rocky, dark forest floor with two types of beetles: 5 dark brown beetles and 5 bright yellow beetles. A bird silhouette looms overhead. Arrows indicate the bird targeting the bright yellow beetles due to high visibility against the dark rock. Below, a small summary box highlights: 'Selection Pressure: Predation' and 'Key Factor: Camouflage'. Styled with clean responsive SVG, text in #1e2945, background #f1f5f9, warm accent colors (#e11d48 for predator focus, #22c55e for survival advantage).
Which individuals make it through this filter to pass on their traits?