Advantageous Traits Spread
Aligned to HS-LS4-3 — Next Generation Science Standards.
What this lesson teaches
When a trait improves survival or reproduction, the individuals carrying it leave more offspring. Over generations, that trait's proportion in the population rises in a way that can be measured.
Worked example
In a moth population, dark moths hidden on soot-darkened tree bark survive birds better; within decades their share climbs from a few percent to the majority.
Practice questions
- From two data sets, describe how a trait's frequency changed over time.
- Calculate the expected proportion of a trait if it doubles each generation for three generations.
- Use probability to support the claim that advantageous traits become more common over time.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Los rasgos ventajosos se propagan
Cuando un rasgo mejora la supervivencia o la reproducción, los individuos que lo portan dejan más descendencia. A lo largo de las generaciones, la proporción de ese rasgo en la población aumenta de una manera que puede medirse.
Ejemplo: En una población de polillas, las polillas oscuras camufladas en la corteza ennegrecida por el hollín sobreviven mejor a las aves; en pocas décadas su proporción sube de unos pocos por ciento a la mayoría.
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