Evolution and Natural Selection Overview

Study Notes

Darwin's Observations and Evolution

English naturalist Charles Darwin conducted research in the Galapagos Islands, focusing on biogeography.
He observed that organisms from South America had colonized the Galapagos, evolving into new species.
Darwin proposed "descent with modification," fundamentally defining evolution as a change in a population's genetic makeup over time.

Evolution and Natural Selection

Evolution involves hereditary traits passed between generations, changing across generations.
Natural selection is the process where organisms with beneficial traits are more likely to survive and reproduce.
Traits are favored because they improve an organism's fitness (ability to survive and reproduce) in their environment.
The environment exerts selective pressure, influencing reproductive success.
Examples of selective pressures are environmental shifts like climate change.

Natural Selection Principles

Heritability: Traits are passed from parents to offspring, driving adaptations.
Overproduction: More offspring are produced than can survive, creating competition for resources.
Differential survival: Environmental pressures lead to varied survival rates among individuals.
Environmental changes affect organism survival rates.

Artificial Selection

This involves selective breeding in domesticated plants and animals to encourage beneficial traits.

Natural Selection vs. Artificial Selection

Natural selection is driven by environmental pressures, while artificial selection is directed by human choices.

Population Genetics

A population is a group of the same species interacting in the same area.
The gene pool encompasses all genetic variation in a population.
Fixed alleles indicate lower genetic diversity.

Drivers of Evolution (Microevolution)

Mutations: Changes in genes that introduce diversity and new alleles. They occur faster in prokaryotes compared to eukaryotes (plants and animals).
Genetic Drift: Random variations in allele frequencies between generations, significant in small populations.
Bottleneck effect: Population reduction due to a disaster.
Founder effect: A new population derived from a small, isolated group.
Gene Flow: Allele transfer between populations, like pollen transfer.
Natural Selection: Three types – directional, stabilizing, and disruptive.
Sexual selection: explains unique traits chosen by mate preference.

Hardy-Weinberg Equilibrium

It's a model used to assess evolution in populations.
It describes the genetic makeup of a non-evolving population.
Five conditions need to be met for the equilibrium to apply: No mutations, random mating, no selection, unlimited population size, and no gene transfer.
If any condition is violated, microevolution occurs.
The formula is p + q = 1 and p² + 2pq + q² = 1.

Description

This quiz explores Charles Darwin's observations, particularly his research in the Galapagos Islands and the concept of evolution through natural selection. Participants will learn about descent with modification and the principles of evolutionary change influenced by environmental factors. Test your understanding of these foundational concepts in evolution!