Theories of Evolution
Change in heritable characteristics of a population over time.
Distinguishes Darwinian evolution from Lamarckism: only genetic changes are evolution.
Nature of Science
Evolution by natural selection predicts and explains a wide range of observations, unlikely to be falsified.
Praised as a strong, pragmatic theory, even if it cannot be formally proven.
Types of evidence supporting evolution:
DNA, RNA and protein sequences.
Homologous Structures.
Selective Breeding.
Definition
Process where humans breed plants/animals for specific traits.
Shows rapid evolutionary changes.
Examples include domesticated animals like dogs (from wolves) and crop plants like Brassica oleracea.
Definition
Similar structures in different species evolved from a common ancestor.
Example: Pentadactyl limb found in humans, birds, dogs, and whales has structural similarities adapted for different functions (grasping, running, flying, swimming).
Definition
Structures with similar functions but differing origins; do not arise from a common ancestor.
Example: Wings of bats, birds, and insects evolve through convergent evolution.
Definition
Formation of new species as a result of evolutionary processes.
Occurs when populations are reproductively isolated.
Gradual change within a species does not constitute speciation.
Types of Isolation
Geographical: Prevents interbreeding across physical barriers (e.g., rivers, mountains).
Behavioral: Different mating behaviors lead to reproductive barriers (e.g., different songs in meadowlarks).
Temporal: Species breeding at different times (e.g., cicadas with different life cycles).
Common ancestor of chimpanzees and bonobos was geographically isolated by the Congo River.
Led to different traits being selected on either side, resulting in speciation.
Allopatric Speciation: Occurs due to geographical isolation.
Sympatric Speciation: Occurs without geographical barriers; reproductive isolation can arise via behavioral or temporal means.
Definition
Rapid evolution of one species into multiple new species as they adapt to various ecological niches.
Example: Darwin's finches evolved from a single ancestor into multiple species on the Galapagos Islands.
Types of Barriers
Prezygotic: Prevent fertilization (e.g., behavioral isolation, temporal isolation).
Postzygotic: Result in hybrid offspring that are inviable or sterile (e.g., mules).
Definition
Condition of having more than two sets of chromosomes, commonly seen in plants.
Can cause immediate speciation.
Evolution, Speciation, Homologous Structures, Analogous Structures, Selective Breeding, Common Ancestor, Pentadactyl Limb, Reproductive Isolation, Geographical Isolation, Convergent Evolution, Adaptive Radiation, Biodiversity.
How does the theory of evolution by natural selection explain the unity and diversity of life on Earth?
What counts as strong evidence in biology?