Evolution and Speciation

Evolution: cumulative change in heritable characters of a population. This occurs across generations and is induced by change events (genetic drift), environmental pressures (natural selection), or human intervention (artificial selection).

Lamark

• Said that species evolve due to a habitual use or disuse of a trait, and that this will result in shrinkage or growth of a feature
• This was disproved because gaining or losing features during one’s lifetime will not alter one’s DNA

Darwin

• Superseded Lamark’s theory
• Suggested that characteristics were chosen by the environment
• Suggested that traits more suitable to specific conditions would become more frequent in a population

Evidence for Evolutionary Change:

• 1. Showing a change in characteristics between modern and ancestral species (via fossils)
• 2. Identifying shared characteristics in many different species (indicates common ancestry)

Evolution vs Artificial Selection

Evolution

• Nature deciding what traits get passed on
• Traits that get passed on benefit the function of an animal and their ability to survive

Artificial Selection

• Humans deciding what traits get passed on
• Traits that get passed on benefit humans (example: practicality, resistance to pests)

Both

• Involves passing on traits to the next generation
• Takes many generations to occur
• Results in population change (feature-wise)

Extinction

Key Concepts:

Types of Diversity

• Genetic Diversity: variety of genes and traits within a species
• Species Diversity: variety of species within an ecosystem
• Ecosystem Diversity: variety of ecosystems within an area
• Diversification: process of speciation leading to an increase in the number of species. This is why there are more species on earth now than ever.

Species Count

• Lumpers: scientists that tend to group species together based on shared characteristics. This leads to lower estimates of the number of species.
• Splitters: scientists that tend to separate species based on apparent differences. This leads to higher estimates of the number of species.
• Species Richness: number of different species in an area
• Species Evenness: relative abundance of the different species in an area

Types of Extinction

• Anthropogenic Mass Extinction: human-induced extinction
• Extinction Gradually: group of organisms progressively evolves into something else
• Extinction Abruptly: species dies without leaving any identifiable descendants

Causes of Anthropogenic Mass Extinction

Remember: O CUPID!

1. Overharvesting

• Hunting animals and harvesting plants

2. Climate change

• Industrialization causes the climate to change too quickly for animals to adapt

3. Urbanization

• Creation of new cities can lead to habitat loss and fragmentation

4. Pollution

• Substances or garbage released into the environment will harm species

5. Invasive Species

• Invasive species can drive native species to extinction

6. Deforestation/Habitat Loss

• Land clearance leads to habitat loss and possible extinction

Conservation

Conservation: protection and preservation of plant or animal species within or outside their natural environment.

In Situ Conservation:

• Within an organism’s natural environment
• Maintains an organism's natural behaviour in food chains

Ex Situ Conservation:

• Outside an organism’s natural habitat
• Allows for greater control of conditions and improves breeding success rates
• Reduces genetic diversity via interbreeding

EDGE (Evolutionary Distinct and Globally Endangered)

• Prioritizes conservation according to two criteria (evolutionary distinct and globally endangered)
• Distinct species have few close relatives
• Globally endangered species defined as "at risk" when at a critically endangered, endangered, or vulnerable status