1. Human vs Natural Selection - Domestic breeding shows how selection works on variations - Natural selection operates similarly but over longer periods - Environment determines which traits are advantageous 2. Contributing Factors: - Sexual selection (mate choice) - Diversification into new environments - Competition for resources - Population balance in ecosystems - Environmental conditions - Correlation of growth (linked traits) 3. Evidence Supporting Theory: - Fossil record (though incomplete) - Geographical distribution of species - Anatomical similarities within classes - Inherited traits/instincts - Sterility in hybrid species
00:10 Introduction 00:39 Domestic breeds are created through human selection. 02:46 Nature may well select traits that help organisms survive, forming different species over many generations. 04:56 Sexual selection and diversification also contribute to natural selection. 06:56 Nature keeps populations in balance as they compete for survival. 08:49 Variation arises from many processes. 11:14 The theory of descent with modification can be defended against naysayers. 13:36 Descent with modification can explain phenomena like instincts and the sterile results of crossbreeding. 15:54 Even though the fossil record is incomplete, it supports the theory of descent with modification. 18:09 Natural selection explains the geographical distribution of species. 20:21 Descent with modification explains similarities between organisms in the same scientific class.
Key Points About Evolution: - Very slow process occurring over many generations - Transitional species often go extinct - Species can't re-emerge once extinct - Complex features develop gradually - Migration affects species distribution - Related species share common ancestors
Core Theory: Natural Selection - Species evolve over time through descent with modification - Organisms with advantageous traits survive and reproduce more successfully - This leads to gradual changes and new species formation
1. Human vs Natural Selection
- Domestic breeding shows how selection works on variations
- Natural selection operates similarly but over longer periods
- Environment determines which traits are advantageous
2. Contributing Factors:
- Sexual selection (mate choice)
- Diversification into new environments
- Competition for resources
- Population balance in ecosystems
- Environmental conditions
- Correlation of growth (linked traits)
3. Evidence Supporting Theory:
- Fossil record (though incomplete)
- Geographical distribution of species
- Anatomical similarities within classes
- Inherited traits/instincts
- Sterility in hybrid species
00:10 Introduction
00:39 Domestic breeds are created through human selection.
02:46 Nature may well select traits that help organisms survive, forming different species over many generations.
04:56 Sexual selection and diversification also contribute to natural selection.
06:56 Nature keeps populations in balance as they compete for survival.
08:49 Variation arises from many processes.
11:14 The theory of descent with modification can be defended against naysayers.
13:36 Descent with modification can explain phenomena like instincts and the sterile results of crossbreeding.
15:54 Even though the fossil record is incomplete, it supports the theory of descent with modification.
18:09 Natural selection explains the geographical distribution of species.
20:21 Descent with modification explains similarities between organisms in the same scientific class.
Key Points About Evolution:
- Very slow process occurring over many generations
- Transitional species often go extinct
- Species can't re-emerge once extinct
- Complex features develop gradually
- Migration affects species distribution
- Related species share common ancestors
Core Theory: Natural Selection
- Species evolve over time through descent with modification
- Organisms with advantageous traits survive and reproduce more successfully
- This leads to gradual changes and new species formation