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Hi there! I'm Studyfin, your science tutor. Today, we are going to explore how life on Earth changes over time and how all living things are connected!
All living things share a common history. We can analyze and evaluate evidence, like matching bone shapes in a whale's flipper and a human's arm, to see how we share a common ancestor.
Natural selection changes populations, not single organisms. It relies on inherited variation, where offspring get different traits, and overproduction, where more babies are born than can survive. Those with helpful traits survive and reproduce.
Over time, helpful traits build up, which can lead to speciation, the creation of a brand new species. Also, species change at different rates: gradualism is slow and steady, while abrupt appearance shows quick shifts after long, quiet periods.
A forest has green trees. A species of beetle lives there. Some are green and some are brown. A new bird species arrives that eats these beetles. Analyze how natural selection will produce change in this beetle population over time.
- Identify the inherited variation: The beetles have two inherited shell colors, green and brown.
- Evaluate the environmental pressure: The new bird predator hunts by sight. Green beetles blend into the green leaves, while brown beetles stand out.
- Analyze survival and reproduction: Brown beetles get eaten more often. Green beetles survive better and have more baby beetles, passing on their green-shell genes.
- Explain the population shift: The population changes as a whole. The percentage of green beetles increases over generations, while brown beetles become rare.
- Connect to speciation: If some beetles move to a brown-dirt area and adapt there, the two groups might eventually become so different they can no longer mate, leading to speciation.
