Questions and Answers
How may different subspecies of giraffe have evolved from a common ancestor?
No interbreeding / gene pools are separate / geographic isolation; mutation linked to different markings; selection/survival linked to different markings; adapted organisms breed; change in allele frequencies.
How did biologists conclude that six of the nine subspecies of giraffe are separate species?
Comparison of DNA base sequences; differences in six species compared to similarities in three.
Describe the changes which occur in lemming and stoat populations over time.
Lemming populations fluctuate in 4-year cycles; stoats peak after lemmings; lemming increases due to low stoat numbers; more stoats lead to decreased lemmings.
How is the movement of lemmings important for maintaining genetic variability?
Signup and view all the answers
Explain how two species of lemming evolved from the original species.
Signup and view all the answers
What is sympatric speciation?
Signup and view all the answers
List two differences between forms T and M of Littorina saxatilis based on environmental factors.
Signup and view all the answers
Study Notes
Giraffe Subspecies Evolution
- Nine giraffe subspecies developed through geographic isolation over long periods.
- Distinct skin markings among subspecies are adaptations influenced by mutation.
- Different markings provide advantages linked to survival and reproductive success.
- As a result, allele frequency changes lead to the differentiation of subspecies.
DNA Analysis and Giraffe Classification
- Mitochondrial DNA comparison among giraffe subspecies indicates species relationships.
- Six out of the nine subspecies have significant DNA differences, supporting separate species classification.
- DNA similarities suggest three remaining subspecies are closely related, classified within the same species.
Lemmings and Stoats Population Dynamics
- Lemming and stoat populations exhibit a four-year cyclical pattern.
- Stoat population peaks follow increases in lemming numbers due to lower predation pressure.
- Lemmings thrive when stoat numbers are low, leading to increased food availability for stoats.
- As stoat numbers rise, predation on lemmings intensifies, resulting in a subsequent decline of the lemming population.
Genetic Variability in Lemmings
- Isolated lemming populations exhibit limited genetic diversity due to fewer alleles and increased homozygosity.
- Migration between populations introduces new alleles, enhancing the gene pool and maintaining genetic variability.
Evolution of Two Lemming Species
- Geographical isolation after glacier melting led to the development of two distinct lemming species.
- Variation and different environmental conditions exert different selection pressures, causing divergent evolution.
- Changes in genetic constitution and allele frequencies resulted in the formation of separate species from the original population.
Sympatric Speciation
- Sympatric speciation occurs without geographic isolation, resulting in the formation of new species within the same area.
- Reproductive isolation is a key factor, disrupting interbreeding between populations.
Littorina saxatilis Snail Forms
- Littorina saxatilis has two forms based on habitat: Form T (top shore) and Form M (middle shore).
- Form T has smaller, thinner shells and lives among rock cracks with less crab predation.
- Form M has larger, thicker shells to withstand greater wave action and increased crab presence.
- Differential survival is influenced by environmental factors such as wave action and predation rates on each form of the snail.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the fascinating concepts of evolution and speciation through this quiz. Understand how giraffes and their subspecies evolved from a common ancestor. This quiz will test your knowledge on the factors influencing speciation and diversification in species.
