Mechanisms of Evolution

Mechanisms of

Evolution

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Content Objective:

Explain the different mechanisms of evolution.

Language Objective:

-Inference and analyze data on variability in populations-Write and share with groups about their lab findings.

Survival of the fittest

Selection

Variation

Adaptations

Adaptations may improve survival (can pass on traits)

There is variation which is inherited in populations

Over many generations, traits change in frequency

Stages of

Natural Selection

Age of metals

Neolithic

Mesolithic

Paleolithic

6.000 b.c

2.500.000 B.C.

10.000 B.C.

8.000 b.c

Innherited variation

Competitions

Environmental pressures

Adaptions

results from overproduction

cause selection

that are beneficial are selected for

exists within a population

Genotype frequency

changes over time

Evolution

occurs within the population

Genetic variation

natural selection requires inheritable variation among members of a species

• Mutations: Germline mutations (in gametes) lead to changed characteristics in offspring
• Meiosis: Crossing over (in prophase 1) and random assortment (in metaphase 1) results in gamete variation
• Sexual Reproduction: The fusion of two different gametes creates a genetically distinct zygote

Adaptations

Selection Pressures

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Environmental agents (selection pressures) will select traits that promote reproductive fitness-Individuals that reproduce will pass on these traits

Features that make an individual suited to its environment -Organisms with beneficial adaptations are likely to survive and reproduce

Genotype frequencies

The presence of beneficial adaptations lead to differential reproduction rates

• Better adapted individuals survive and pass on their genes to offspring
• Less well adapted individuals tend to die and produce fewer offspring