BackAP Biology – The Origin of Species: Guided Study Support
Study Guide - Smart Notes
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Q1. What is speciation? How does it relate to microevolution and macroevolution? What is the “bridge” between these two forms of evolution?
Background
Topic: Speciation and Evolutionary Scales
This question explores the definition of speciation and its role as a connection between microevolution (small-scale changes within populations) and macroevolution (large-scale evolutionary changes, such as the emergence of new species).
Key Terms:
Speciation: The process by which one species splits into two or more distinct species.
Microevolution: Evolutionary changes within a population or species, typically involving allele frequency shifts.
Macroevolution: Evolutionary changes that result in the formation of new species or groups above the species level.
Step-by-Step Guidance
Start by defining speciation in your own words, focusing on the process of splitting one species into two or more.
Explain how microevolution involves changes within a population, such as shifts in allele frequencies due to mutation, selection, gene flow, or genetic drift.
Describe macroevolution as the broader pattern of evolutionary change that leads to the emergence of new species and higher taxonomic groups.
Think about what process connects microevolutionary changes to macroevolutionary outcomes—this is the “bridge” the question refers to.
Try solving on your own before revealing the answer!
Q2. According to the biological species concept, define species.
Background
Topic: Species Concepts
This question tests your understanding of the biological species concept, which is a key framework for defining what a species is in biology.
Key Terms:
Biological Species Concept: A way of defining species based on reproductive isolation.
Reproductive Isolation: The inability of different species to produce fertile offspring together.
Step-by-Step Guidance
Recall the main criterion used by the biological species concept to define a species.
Think about how this concept distinguishes between different species based on their ability to interbreed and produce viable, fertile offspring.
Consider why reproductive isolation is central to this definition.
Try solving on your own before revealing the answer!
Q3. What evolutionary mechanism can lead to the formation of new species especially when it is reduced or lacking between populations?
Background
Topic: Mechanisms of Speciation
This question asks you to identify an evolutionary mechanism that, when reduced or absent, can promote speciation between populations.
Key Terms:
Gene Flow: The transfer of alleles or genes from one population to another.
Speciation: The formation of new and distinct species in the course of evolution.
Step-by-Step Guidance
Think about what keeps populations genetically similar to each other.
Consider what happens when this mechanism is reduced or absent—does it increase or decrease the likelihood of speciation?
Identify the evolutionary mechanism that, when limited, allows populations to diverge genetically and potentially form new species.
Try solving on your own before revealing the answer!
Q4. What is reproductive isolation? Define interspecific mating and intraspecific mating. Which of these two types of mating leads to a hybrid?
Background
Topic: Reproductive Barriers and Hybridization
This question focuses on reproductive isolation and the difference between mating within a species and between species, as well as the concept of hybrids.
Key Terms:
Reproductive Isolation: Biological barriers that prevent different species from interbreeding and producing fertile offspring.
Interspecific Mating: Mating between individuals of different species.
Intraspecific Mating: Mating between individuals of the same species.
Hybrid: Offspring resulting from the mating of individuals from two different species.
Step-by-Step Guidance
Define reproductive isolation and explain its importance in maintaining species boundaries.
Clarify the difference between interspecific and intraspecific mating.
Determine which type of mating produces hybrids and why.
Try solving on your own before revealing the answer!
Q5. Define prezygotic barriers and postzygotic barriers.
Background
Topic: Mechanisms of Reproductive Isolation
This question asks you to distinguish between two main types of reproductive barriers that prevent species from interbreeding.
Key Terms:
Prezygotic Barriers: Barriers that prevent mating or fertilization between species.
Postzygotic Barriers: Barriers that occur after fertilization, affecting the viability or fertility of hybrids.
Step-by-Step Guidance
Define what a prezygotic barrier is and give a general example.
Define what a postzygotic barrier is and give a general example.
Think about the timing of these barriers in relation to fertilization (before or after the zygote forms).
Try solving on your own before revealing the answer!
Q6. List and describe the 5 types of prezygotic barriers.
Background
Topic: Prezygotic Barriers to Reproduction
This question requires you to recall and describe the five main types of barriers that prevent fertilization between species.
Key Terms:
Prezygotic Barriers: Mechanisms that prevent mating or fertilization between species.
Step-by-Step Guidance
List each of the five types of prezygotic barriers (think about timing, behavior, physical compatibility, etc.).
For each barrier, write a brief description of how it prevents fertilization.
Consider examples for each type to help clarify your understanding.
Try solving on your own before revealing the answer!
Q7. List and describe the 3 types of postzygotic barriers.
Background
Topic: Postzygotic Barriers to Reproduction
This question asks you to identify and describe the three main types of barriers that affect hybrids after fertilization.
Key Terms:
Postzygotic Barriers: Mechanisms that reduce the viability or reproductive capacity of hybrid offspring.
Step-by-Step Guidance
List the three main types of postzygotic barriers.
Describe how each barrier affects hybrid offspring (think about survival, fertility, and breakdown in later generations).
Provide an example for each type if possible.
Try solving on your own before revealing the answer!
Q8. State 3 limitations to the biological species concept.
Background
Topic: Species Concepts and Their Limitations
This question focuses on the weaknesses or limitations of using the biological species concept to define species.
Key Terms:
Biological Species Concept: Defines species based on reproductive isolation.
Limitations: Situations where the concept does not apply well (e.g., asexual organisms, fossils).
Step-by-Step Guidance
Think about cases where the biological species concept cannot be applied (e.g., organisms that do not reproduce sexually).
Consider situations involving extinct species or fossils.
Reflect on cases where gene flow occurs between distinct species (e.g., hybridization).
Try solving on your own before revealing the answer!
Q9. What is the morphological species concept? What is a limitation of this concept?
Background
Topic: Alternative Species Concepts
This question asks you to define the morphological species concept and recognize one of its main limitations.
Key Terms:
Morphological Species Concept: Defines species based on physical characteristics.
Limitation: Potential for subjective interpretation of traits.
Step-by-Step Guidance
Define the morphological species concept in your own words.
Identify a limitation, such as difficulty distinguishing species with similar appearances or high variability within a species.
Try solving on your own before revealing the answer!
Q10. What is the ecological species concept?
Background
Topic: Alternative Species Concepts
This question focuses on the ecological species concept, which defines species based on their ecological niche.
Key Terms:
Ecological Species Concept: Defines species based on their role in the environment (niche).
Niche: The sum of a species’ use of biotic and abiotic resources in its environment.
Step-by-Step Guidance
Define the ecological species concept, focusing on the idea of ecological niche.
Consider how this concept distinguishes species based on their interactions with the environment and other organisms.
Try solving on your own before revealing the answer!
Q11. How many definitions of species have been proposed? Which concept will be used in your textbook to discuss how species originated?
Background
Topic: Species Concepts in Biology
This question asks you to recognize the diversity of species definitions and identify which one is emphasized in your course or textbook.
Key Terms:
Species Concepts: Different frameworks for defining what a species is (biological, morphological, ecological, etc.).
Step-by-Step Guidance
Recall that multiple species concepts exist in biology (think about the main three discussed so far).
Identify which concept is most commonly used in your textbook to explain the origin of species.
Try solving on your own before revealing the answer!
Q12. What is allopatric speciation? How formidable must a geographic barrier be to promote allopatric speciation?
Background
Topic: Modes of Speciation
This question explores allopatric speciation, which involves geographic separation, and asks about the strength of barriers needed for this process.
Key Terms:
Allopatric Speciation: Speciation that occurs when populations are geographically separated.
Geographic Barrier: Physical separation that prevents gene flow between populations.
Step-by-Step Guidance
Define allopatric speciation and explain the role of geographic isolation.
Consider what types of barriers (mountains, rivers, etc.) can prevent gene flow.
Think about whether the barrier must be absolute or if even small barriers can be effective, depending on the species.
Try solving on your own before revealing the answer!
Q13. After geographic isolation, what are the 4 steps that need to take place for speciation to occur?
Background
Topic: Steps in Allopatric Speciation
This question asks you to outline the sequence of events that lead from geographic isolation to the formation of new species.
Key Terms:
Geographic Isolation: Physical separation of populations.
Speciation Steps: The processes that occur after isolation to complete speciation.
Step-by-Step Guidance
List the four main steps that follow geographic isolation (think about genetic divergence, reproductive barriers, etc.).
Briefly describe what happens at each step.
Try solving on your own before revealing the answer!
Q14. What is sympatric speciation? What three factors lead to sympatric speciation?
Background
Topic: Modes of Speciation
This question focuses on sympatric speciation, which occurs without geographic separation, and the factors that can drive it.
Key Terms:
Sympatric Speciation: Speciation that occurs within a shared geographic area.
Factors: Mechanisms such as polyploidy, habitat differentiation, and sexual selection.
Step-by-Step Guidance
Define sympatric speciation and contrast it with allopatric speciation.
List the three main factors that can lead to sympatric speciation.
Briefly describe how each factor contributes to reproductive isolation within the same geographic area.
Try solving on your own before revealing the answer!
Q15. What is polyploidy speciation? Which type of organisms is polyploidy most common?
Background
Topic: Genetic Mechanisms of Speciation
This question asks about polyploidy as a mechanism of speciation and which organisms it most commonly affects.
Key Terms:
Polyploidy: The condition of having more than two complete sets of chromosomes.
Speciation: Formation of new species due to genetic changes.
Step-by-Step Guidance
Define polyploidy and explain how it can lead to the formation of new species.
Identify which group of organisms (plants or animals) most commonly undergoes polyploid speciation.
Try solving on your own before revealing the answer!
Q16. What is an autopolyploid? What causes autopolyploidy? What stage of meiosis leads to autopolyploidy?
Background
Topic: Types of Polyploidy
This question explores the concept of autopolyploidy, its causes, and the meiotic stage involved.
Key Terms:
Autopolyploid: An organism with more than two chromosome sets, all from a single species.
Meiosis: The process of cell division that produces gametes.
Step-by-Step Guidance
Define autopolyploid and explain how it differs from allopolyploid.
Describe the cellular or genetic event that causes autopolyploidy (e.g., nondisjunction).
Identify the stage of meiosis where this error typically occurs.
Try solving on your own before revealing the answer!
Q17. What is an allopolyploid? Who can these organisms mate with?
Background
Topic: Types of Polyploidy
This question focuses on allopolyploidy, which involves chromosome sets from different species, and asks about their reproductive compatibility.
Key Terms:
Allopolyploid: An organism with chromosome sets from two or more different species.
Step-by-Step Guidance
Define allopolyploid and explain how it forms.
Consider whether allopolyploids can mate with parent species or only with other allopolyploids.
Try solving on your own before revealing the answer!
Q18. What is a hybrid zone? Where are hybrid zones located? Are hybrid zones related to allopatric or sympatric speciation?
Background
Topic: Hybrid Zones and Speciation
This question asks you to define hybrid zones, describe their typical locations, and relate them to modes of speciation.
Key Terms:
Hybrid Zone: A region where members of different species meet and mate, producing hybrids.
Allopatric/Sympatric Speciation: Modes of speciation involving geographic separation or not.
Step-by-Step Guidance
Define what a hybrid zone is and what occurs there.
Describe where hybrid zones are typically found (e.g., areas where ranges of two species overlap).
Consider whether hybrid zones are more closely associated with allopatric or sympatric speciation.
Try solving on your own before revealing the answer!
Q19. What would you expect the frequency of alleles to be for a species in the middle of a hybrid zone?
Background
Topic: Genetics of Hybrid Zones
This question asks you to predict allele frequencies in populations located within hybrid zones.
Key Terms:
Allele Frequency: The proportion of a specific allele among all alleles in a population.
Hybrid Zone: Area where two species interbreed.
Step-by-Step Guidance
Consider what happens genetically when two species interbreed in a hybrid zone.
Think about whether allele frequencies would be intermediate, similar to one parent species, or highly variable.
Try solving on your own before revealing the answer!
Q20. Are hybrids more or less likely to survive and reproduce healthy, viable offspring?
Background
Topic: Hybrid Viability and Fertility
This question asks you to consider the fitness of hybrids compared to parent species.
Key Terms:
Hybrid: Offspring of two different species.
Viable: Capable of surviving and reproducing.
Step-by-Step Guidance
Recall what typically happens to hybrids in terms of survival and fertility.
Consider whether hybrids are usually more or less fit than parent species.
Try solving on your own before revealing the answer!
Q21. How can environmental change affect hybrid zones?
Background
Topic: Environmental Effects on Hybrid Zones
This question explores how changes in the environment can influence the dynamics of hybrid zones.
Key Terms:
Hybrid Zone: Area where two species interbreed.
Environmental Change: Alterations in habitat, climate, or other ecological factors.
Step-by-Step Guidance
Think about how changes in the environment might alter the range or behavior of species involved in a hybrid zone.
Consider whether environmental changes could increase, decrease, or shift the location of hybrid zones.
Try solving on your own before revealing the answer!
Q22. Explain the three common outcomes of hybrid zones over time.
Background
Topic: Outcomes of Hybridization
This question asks you to describe the possible long-term outcomes for species in hybrid zones.
Key Terms:
Hybrid Zone: Area where two species interbreed.
Outcomes: Reinforcement, fusion, stability.
Step-by-Step Guidance
List the three main outcomes for hybrid zones over time.
Briefly describe what happens in each outcome (e.g., increased reproductive barriers, merging of species, continued hybridization).
Try solving on your own before revealing the answer!
Q23. Patterns in the fossil records can provide information on how long it takes for new species to form. Explain the two models (punctuated model and gradual model) that have been observed in fossil records.
Background
Topic: Tempo of Speciation
This question asks you to compare two models of evolutionary change as seen in the fossil record.
Key Terms:
Punctuated Model: Evolutionary change occurs in rapid bursts separated by long periods of stability.
Gradual Model: Evolutionary change occurs slowly and steadily over time.
Step-by-Step Guidance
Define the punctuated model and describe its pattern in the fossil record.
Define the gradual model and describe its pattern in the fossil record.
Compare and contrast the two models in terms of the tempo and mode of speciation.
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Q24. On average, how often do speciation events occur?
Background
Topic: Rate of Speciation
This question asks you to consider the average time frame for speciation events based on scientific evidence.
Key Terms:
Speciation Event: The process by which a new species arises.
Step-by-Step Guidance
Recall estimates from fossil records or studies on living species regarding the average duration of speciation.
Consider the range of time frames that have been observed (e.g., thousands to millions of years).
Try solving on your own before revealing the answer!
Q25. List the steps of speciation.
Background
Topic: Process of Speciation
This question asks you to summarize the main steps involved in the formation of new species.
Key Terms:
Speciation: The process by which new species arise.
Step-by-Step Guidance
List the general sequence of events that lead to speciation (e.g., isolation, divergence, reproductive barriers).
Briefly describe what occurs at each step.
Try solving on your own before revealing the answer!
