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Questions and Answers
What defines homologous structures in animals?
What defines homologous structures in animals?
- Body parts that are visually similar and function similarly
- Body parts that have different structures but similar functions
- Body parts that are identical in structure and function
- Body parts that have structural similarities but different functions (correct)
What is one key aspect of adaptive radiation?
What is one key aspect of adaptive radiation?
- It illustrates how shared structures adapt in various environments (correct)
- It explains the differences in muscle structure across species
- It focuses on genetic variations without structural considerations
- It is conclusive proof of a common ancestor for species
Which of the following is an example of a homologous structure?
Which of the following is an example of a homologous structure?
- The fins of fish and the flippers of seals
- The wings of insects and birds
- The forelimbs of mammals like dogs and whales (correct)
- The stems of plants and the trunks of trees
Which aspect of the pentadactyl limb is significant?
Which aspect of the pentadactyl limb is significant?
Why is the concept of homologous structures important in studying evolution?
Why is the concept of homologous structures important in studying evolution?
What is required for speciation to occur?
What is required for speciation to occur?
How does extinction impact biodiversity?
How does extinction impact biodiversity?
Which statement is true about genetic differences between populations?
Which statement is true about genetic differences between populations?
What happens when two populations become reproductively isolated?
What happens when two populations become reproductively isolated?
Which of these species is an example of extinction reducing diversity?
Which of these species is an example of extinction reducing diversity?
What is the main characteristic of analogous structures?
What is the main characteristic of analogous structures?
How do analogous structures contribute to natural selection?
How do analogous structures contribute to natural selection?
Why have analogous structures historically caused confusion in taxonomy?
Why have analogous structures historically caused confusion in taxonomy?
Which of the following pairs represents an example of convergent evolution?
Which of the following pairs represents an example of convergent evolution?
What primarily drives convergent evolution between unrelated species?
What primarily drives convergent evolution between unrelated species?
What is a characteristic of cacti and euphorbia that illustrates convergent evolution?
What is a characteristic of cacti and euphorbia that illustrates convergent evolution?
What distinguishes homologous structures from analogous structures?
What distinguishes homologous structures from analogous structures?
Which of the following statements about convergent evolution is true?
Which of the following statements about convergent evolution is true?
What is the primary consequence of reproductive isolation?
What is the primary consequence of reproductive isolation?
Which is an example of a behavioral change that can lead to reproductive isolation?
Which is an example of a behavioral change that can lead to reproductive isolation?
What role does geographical isolation play in the process of speciation?
What role does geographical isolation play in the process of speciation?
How can a body of water contribute to reproductive isolation?
How can a body of water contribute to reproductive isolation?
What is meant by differential selection?
What is meant by differential selection?
Which of the following statements is true regarding populations that are geographically isolated?
Which of the following statements is true regarding populations that are geographically isolated?
What is one potential result when two populations of the same species become reproductively isolated?
What is one potential result when two populations of the same species become reproductively isolated?
Which of the following best describes the initial factor leading to reproductive isolation?
Which of the following best describes the initial factor leading to reproductive isolation?
What is behavioral isolation?
What is behavioral isolation?
What does the term 'allele frequency' refer to?
What does the term 'allele frequency' refer to?
What is a consequence of reduced gene flow between two populations?
What is a consequence of reduced gene flow between two populations?
How can sympatric speciation occur according to the given example?
How can sympatric speciation occur according to the given example?
What role do random mutations play in sympatric speciation?
What role do random mutations play in sympatric speciation?
Which factor might cause different alleles to become more frequent in each population?
Which factor might cause different alleles to become more frequent in each population?
What happens when enough allele frequency differences arise between two populations?
What happens when enough allele frequency differences arise between two populations?
What is an example of a change in phenotype mentioned in the sympatric speciation of fruit flies?
What is an example of a change in phenotype mentioned in the sympatric speciation of fruit flies?
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Study Notes
Variation in Brassica Plants
- Wild Brassica plants exhibit significant variation that has enabled selective breeding of many contemporary crop species.
Homologous Structures
- Homologous structures share a similar layout but may perform different functions across species.
- Example: Limbs of birds, bats, crocodiles, whales, horses, and monkeys exhibit similar bone arrangements despite differing appearances and uses.
- Adaptive radiation explains the evolution of homologous structures from a common ancestor adapting to diverse environments.
Convergent Evolution
- Analogous structures are formed from separate evolutionary paths but fulfill similar functions, leading to confusion in taxonomy.
- Convergent evolution occurs under similar environmental pressures, resulting in similar adaptations in distantly related species.
- Example: Dolphins (mammals) and sharks (fish) exhibit similar body shapes due to adaptations to aquatic environments, despite being different classes.
- Example: Cacti (Americas) and euphorbia (Africa) have evolved similar structures independently as adaptations to desert habitats.
Speciation
- Speciation contributes to Earth's biodiversity; genetic differences accumulate when populations become isolated.
- Reproductive Isolation: Prevents interbreeding between populations, resulting in speciation if genetic divergence is significant.
- Factors causing reproductive isolation:
- Seasonal changes (different mating times).
- Behavioral changes (altered courtship behaviors).
Geographical Isolation
- Occurs when natural or man-made barriers separate populations, preventing gene exchange.
- Examples of barriers include mountains, rivers, or highways.
- Differential selection pressure may lead to diverse adaptations in geographically isolated populations.
- Over time, populations can become sufficiently distinct to promote speciation.
Sympatric Speciation
- Occurs when a random mutation leads to distinct phenotypes within a population, preventing interbreeding.
- Example: In fruit flies, a mutation alters food preference, resulting in different phenotypes that do not interbreed, leading to distinct species over time.
- Changes in allele frequencies within isolated populations reinforce reproductive isolation, culminating in speciation.
Extinction and Diversity
- Extinction decreases biodiversity; not all species that have existed remain today (e.g., passenger pigeon, woolly mammoth).
- While speciation increases diversity, extinction counteracts this effect.
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