Environmental Change and Species
Aligned to HS-LS4-5 — Next Generation Science Standards.
What this lesson teaches
When the environment changes, species with suited traits may thrive, others may decline, and isolated groups can diverge into new species. Species that cannot keep pace may go extinct.
Worked examples
Example 1
When a land bridge split one lizard population into two habitats, each group adapted separately over thousands of years until they could no longer interbreed, forming two new species.
Example 2
Speciation does not need a physical barrier. Two groups using different food or breeding at different times can diverge in the same place.
Example 3
The line is not sharp. Some separated populations can still interbreed and produce fertile young, and biologists argue about where to draw it.
Practice questions
- Describe how one environmental change affected a species' numbers.
- Show how a physical barrier could split one species into two over time.
- Evaluate evidence for whether a climate shift would more likely cause extinction or new species.
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
Cambio ambiental y especies
Cuando el ambiente cambia, las especies con rasgos adecuados pueden prosperar, otras pueden disminuir y los grupos aislados pueden divergir en nuevas especies. Las especies que no logran adaptarse a tiempo pueden extinguirse.
Ejemplo 1: Cuando un puente de tierra dividió una población de lagartijas en dos hábitats, cada grupo se adaptó por separado durante miles de años hasta que ya no pudieron cruzarse, formando dos nuevas especies.
Ejemplo 2: La especiación no necesita una barrera física. Dos grupos que usan distinto alimento o se reproducen en momentos distintos pueden divergir en el mismo lugar.
Ejemplo 3: La línea no es nítida. Algunas poblaciones separadas todavía pueden cruzarse y tener crías fértiles, y los biólogos discuten dónde trazarla.
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