Unit 8.4 - Beyond Natural Selection: Mechanisms of Evolution

The first to describe a working mechanism for evolution by natural selection:

• Gregor Mendel

• Charles Darwin

• Albert Einstein

• Antonie van Leeuwenhoek

Answer explanation

By observing the biodiversity in the Galapagos Islands, Charles Darwin developed his theory of evolution by natural selection.

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Match the following

• Artificial Selection

• The biological process of change over time by which descendants come to differ from their ancestors

• Natural Selection

• Organisms with traits better suited to their environment are more likely to survive and reproduce

• Evolution

• Humans breed plants or animals for favored traits

Answer explanation

• - natural selection = "survival of the fittest"

• - evolution = "change"

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Evolution of populations depends on 4 main factors. Match:

• Heritability of traits

• The geologic record shows that life has existed on Earth for 3.5 billion years

• Environmental Pressures

• Differences in DNA between individuals causing unique traits in a population

• Time

• The natural forces that affect survival (ex. predators, competition for resources)

• Genetic variation

• Characteristics that can be passed from parents to offspring

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Identify the population(s) with the lowest genetic diversity.

Answer explanation

Small populations tend to have low genetic diversity (less variety).

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Identify the population(s) most likely to survive a natural disaster.

Answer explanation

Large populations, with higher genetic diversity, are more likely to survive disasters.

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Populations with​ (a)   genetic diversity can survive changes to the environment ​ (b)   populations with ​ (c)   genetic diversity.

• high
• better than
• low

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Select the 2 examples of populations that are affected by low genetic diversity.

• 
• 
• 
• 

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Match the following types of isolation that can lead to speciation:

• Geographic isolation

• Populations are physically separated by barriers like mountains or rivers, preventing them from interbreeding.

• Behavioral isolation

• Populations reproduce at different times (seasons, day/night, or years).

• Temporal isolation

• Differences in mating rituals or courtship prevent interbreeding.

Answer explanation

• - geography = land, mountains, rivers

• - temporal = time

• - behaviors = actions

The founder effect happens when a small group of individuals starts a new population in a different location. As a result, genetic diversity is usually ​ (a)   .

• lowered
• increased
• unchanged

Answer explanation

Smaller populations usually have lower genetic diversity.

Match the following terms:

• Speciation

• The movement of genes between populations

• Gene flow

• Random changes in a DNA sequence that create a new version of a gene, called an allele

• Mutation

• The variety of life, including all species, their genes, and their environments

• Biodiversity

• Populations become separated and stop interbreeding

• Reproductive isolation

• Groups of organisms become so different they can no longer breed to produce fertile offspring

Answer explanation

• - species - similar organisms that can breed to produce fertile offspring

• - speciation - the evolutionary process by which populations evolve to become distinct, reproductively isolated species

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