Macroevolution Flashcards
What is macroevolution, and what does it study?
Macroevolution studies the shape of the tree of life and evolution above the species level, such as the evolution of whales over millions of years. It highlights traits, adaptation, and intermediate forms despite gaps in the fossil record.
How does the tree of life relate to macroevolution?
The tree of life is not symmetrical and reflects evolutionary patterns across multiple scales, including microevolution, speciation, and macroevolution.
What is the difference between microevolution and macroevolution?
Microevolution: Processes within species, such as changes in allele frequency, mutation, migration, selection, drift, adaptation, and sexual selection.
Macroevolution: Focuses on clade success or failure, diversification rates, and species selection across taxonomic boundaries.
What are diversification rates in macroevolution, and what affects them?
Diversification rates are the rates at which groups speciate or go extinct. Groups with higher speciation rates, lower extinction rates, or both tend to diversify faster.
How do self-compatible (SC) and self-incompatible (SI) lineages differ in diversification?
SI lineages: Diversify more but less frequently.
SC lineages: Experience higher extinction rates but gain immediate selective advantages.
What are examples of intermediate forms in turtle evolution?
Archelon: Giant sea turtle with no shell, had open bone framework.
Proganochelys: Oldest land turtle with armored spikes, a carapace, and some teeth.
Odontochelys: Older species with a full bony shell on the belly but not on the back, showing a transition from no shell to half shell.
What are key evolutionary changes in whale evolution?
Transition from terrestrial to marine organisms.
Migration of nostrils to form a single blowhole.
Adaptation to freshwater and saltwater environments, as shown by isotopes.
How are inactivated genes evidence of whale evolution?
Inactivated genes reflect traits no longer needed, supporting common ancestry with terrestrial mammals.
Examples include blood coagulation genes, DNA repair genes, and melatonin regulation genes.
Why might a gene become inactivated during evolution?
Neutral mutations: Fixation through random drift without fitness effects.
Selective advantages: Saves energy, eliminates unnecessary traits, or adapts to new environments.
What are specific examples of inactivated genes in whales?
Blood coagulation genes: Allow rapid diving without coagulation issues.
DNA repair genes: Reduce errors from reactive oxygen species (ROS) during dives.
Melatonin genes: Adapt to stay alert and regulate body temperature without full sleep.
What are gradualism and saltation in evolutionary theory?
Gradualism: Evolution occurs through gradual, cumulative changes over time (e.g., turtles and cetaceans).
Saltation: Suggests large evolutionary jumps, often involving chromosomal rearrangements, which is a less supported theory.
How do intermediate forms support gradualism?
Intermediate forms provide evidence of stepwise transitions, such as changes in turtle shells and whale blowholes, building a detailed evolutionary picture.
