I/GCSE Biology - Evolution by natural selection

In I/GCSE Biology, natural selection is commonly asked in exam!

• Characteristics selected from breeding species e.g. dogs, change over time
• Theory of evolution ➡️ the theory that explains how all living things today have been produced by the accumulation of inherited changes in the characteristics of populations through successive generations.

It's very important to memorize what natural selection is in I/GCSE Biology!

Darwin observed from organisms

1. Organisms produce many more offspring than survive to adulthood
2. There is variation between the individuals of a species and in the offspring they produce
3. Characteristics are passed from one generation to the next
4. The individuals that are best adapted to the environment are the ones that survive and produce offspring in the next generation

Characteristics best adapted ➡️ increase in population in next generation = natural selection

• Natural selection ➡️ a natural process whereby the organisms with genetic characteristics best suited to their environment survive to reproduce and pass on their genes to the next generation

• Evolution because of environment change
• Different characteristics best suited to new conditions
• Best suited ➡️ survive + breed
• Characteristics changed so much, organisms become new species

Variation in inherited characteristics between individuals caused by having different forms of genes

• Different forms caused by mutations

Mutation ➡️ a change in a gene that may result in different characteristics

• Mutations no effect on survival – some ➡️ fatal/disadvantageous e.g. miscarriage but some ➡️ advantageous
• For example:
• Africans ➡️ dark skin, protects from sunlight (homo sapiens evolved from Africa)
• Northern areas ➡️ pale skin (genetic mutation)– improves health in people in that area
• Rate of change in species ➡️ not constant – depends on how quick environment changes + difficulty rate to survive in new conditions
• If conditions changed so much then no variation will survive and species become extinct

And we're done with this topic! Well Done!

CLICK HERE TO LEARN MORE ABOUT OUR I/GCSE BIOLOGY COURSES

Drafted by Alyssa (Biology)

References:

1. "Darwin's Contribution-The Theory of Evolution & Natural Selection", https://cdn1.byjus.com/wp-content/uploads/2015/12/Evolution.jpg
2. "EVOLUTION CHARLES DARWIN IN LATER YEARS 1 HISTORY", https://slidetodoc.com/presentation_image_h/2d9392e857d025f3fb715276296425ed/image-34.jpg
3. "Natural Selection", https://ib.bioninja.com.au/_Media/natural-selection_med.jpeg
4. "Evolution", https://fayllar.org/evolution-are-the-changes-in-the-gene-pool-of-a-population-ove/img12.jpg
5. "Directed evolution", https://dnadots.minipcr.com/wp-content/uploads/2018/10/directed-evolution.png