IB Biology Topic 4 Notes
This page contains our IB Biology notes for topic 4. By reading each one of these notes, you will fully cover the content for IB Biology 'Ecosystems'.
Chapters
A4.1: Evolution & speciation
A4.1: Further speciation (HL)
A4.2: Conservation of biodiversity
B4.1: Adaptations
B4.2: Ecological niches
C4.1: Populations & communities
C4.2: Energy & matter transfer
D4.1: Natural selection
D4.1: Further natural selection (HL)
D4.2: Stability & change
D4.2: Ecological stability (HL)
D4.3: Climate changes
D4.3: Further climate change (HL)
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Evolution
Topic 4 focuses on ecosystems and changes within them. In the context of organisms, the changes they undergo are mostly due to evolution. This is the change in heritable characteristics of a species over time.
Given evolution's previously controversial history since its proposition of theory in the mid 19th-century by Charles Darwin and Alfred Russel Wallace, it is important to understand the process.
The theory of evolution by natural selection is governed by four tenets:
- More offspring are produced than can survive.
- Morphology, physiology, and behavior greatly varies between individuals.
- Different traits results in different rates of survival and reproduction.
- Traits are passed down generations.
The evidence for evolution is provided by several key pieces of information, including:
- Base sequences
- The fossil record
- Selective breeding
- Homologous structures
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