Biology Chapter 23: Systematics and Evolution

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Questions and Answers

What is a synapomorphy?

A shared derived trait found only in a small group of organisms (correct)

A trait that has evolved independently in two different lineages

A trait that is present in all descendants of a common ancestor

A shared ancestral trait found in a small group of organisms

Which of the following is an example of a derived character in mammals?

Presence of hair (correct)

Presence of lungs

Presence of gills

Presence of a backbone

What is an outgroup in phylogenetic analysis?

A closely related species that is used as a reference point (correct)

A species that exhibits all of the derived characters

A species that exhibits all of the ancestral characters

A species that is not related to the group being studied

What is homoplasy?

A shared character state that is not due to common ancestry (C) Signup and view all the answers

Which of the following is an example of homoplasy?

All of the above (D) Signup and view all the answers

Why can DNA sequences be a challenge for phylogenetic analysis?

DNA sequences evolve at different rates (D) Signup and view all the answers

Which of the following is a symplesiomorphy?

Presence of a backbone in vertebrates (D) Signup and view all the answers

Which of the following statements about character states is TRUE?

Character states can be either derived or ancestral depending on the context (D) Signup and view all the answers

Which of the following is a limitation of selection?

All of the above (D) Signup and view all the answers

What is the primary characteristic of stabilizing selection?

Eliminating both extreme phenotypes (C) Signup and view all the answers

What is the significance of Darwin's finches in understanding evolution?

They demonstrate how beak shape can vary within a species (C) Signup and view all the answers

Why is the process of fossilization considered a rare event?

Most organisms do not have hard, mineralized structures (B) Signup and view all the answers

Which of the following is an example of artificial selection?

The development of different breeds of dogs (C) Signup and view all the answers

What type of dating method is used to estimate the age of very old fossils?

Potassium-40 dating (C) Signup and view all the answers

Which of the following is an example of a phenotypic effect of alleles?

Both A and B (C) Signup and view all the answers

What is a holotype?

The first organism found of a specific species (B) Signup and view all the answers

Which of the following is NOT an example of a food source for Darwin's finches?

Leaves (D) Signup and view all the answers

What is the significance of intermediate forms in understanding evolutionary transitions?

They demonstrate how major transitions occurred in small steps (C) Signup and view all the answers

Which of the following is NOT a condition necessary for evolution by natural selection?

Individuals must be able to move to new environments. (A) Signup and view all the answers

Which of the following is an example of genetic drift?

A population of butterflies is blown to an island, and only the orange and black butterflies survive. (B) Signup and view all the answers

What is the primary difference between assortative mating and disassortative mating?

Assortative mating favors individuals with similar phenotypes, while disassortative mating favors individuals with different phenotypes. (A) Signup and view all the answers

Which of the following is NOT a mechanism of gene flow?

Mutation of genes within a population. (A) Signup and view all the answers

What is the effect of a bottleneck event on a population's genetic diversity?

Bottleneck events decrease genetic diversity. (B) Signup and view all the answers

Which of the following is an example of assortative mating?

A female bird chooses to mate with the male bird that sings the loudest song. (B) Signup and view all the answers

How does genetic drift differ from natural selection?

Genetic drift acts on random chance, while natural selection acts on fitness. (B) Signup and view all the answers

Why is a large population size important for maintaining Hardy-Weinberg equilibrium?

A large population size minimizes the effects of genetic drift. (C) Signup and view all the answers

Which of the following concepts defines species based on shared derived characters?

Phylogenetic Species Concept (B) Signup and view all the answers

Which of the following structures are homologous structures?

The wing of a bat and the flipper of a whale (C) Signup and view all the answers

What is the significance of pharyngeal pouches in early vertebrate embryos?

They indicate that vertebrates evolved from a common ancestor. (D) Signup and view all the answers

Which of the following is NOT an example of a vestigial structure?

The scales of a fish (A) Signup and view all the answers

The giraffe's seven vertebrae compared to other mammals is an example of?

Imperfect adaptation (A) Signup and view all the answers

What is the term for the study of the development of an organism?

Ontogeny (D) Signup and view all the answers

The statement 'Ontogeny reflects phylogeny' implies that

The development of an organism mirrors its evolutionary history (C) Signup and view all the answers

Which of the following is NOT a reason why the eyes of vertebrates are not considered perfectly adapted?

The eyes are too sensitive to light. (C) Signup and view all the answers

The Archaeopteryx fossil is considered an important piece of evidence for evolution because it

Reveals a clear link between birds and dinosaurs, showcasing a transitional form. (A) Signup and view all the answers

What is the difference between evolution and natural selection?

Evolution is the historical record of changes over time, while natural selection is the mechanism that drives those changes. (B) Signup and view all the answers

What is meant by "fitness" in the context of evolution?

The ability to survive and reproduce. (D) Signup and view all the answers

What is an example of intrasexual selection?

Male elephant seals fighting for dominance over a group of females. (C) Signup and view all the answers

What is an example of negative frequency-dependent selection?

A rare color pattern in a butterfly population that makes it less vulnerable to predators. (A) Signup and view all the answers

What is an example of disruptive selection?

A population of birds with a range of beak sizes, but those with intermediate beak sizes are unable to effectively obtain food and are eliminated. (B) Signup and view all the answers

Which of the following is NOT a component of fitness?

Physical strength. (A) Signup and view all the answers

How does oscillating selection affect a population?

It maintains genetic variation by favoring different traits at different times. (C) Signup and view all the answers

Why does disruptive selection lead to the elimination of intermediate phenotypes?

Intermediate phenotypes lack the adaptations necessary for survival in the environment. (A) Signup and view all the answers

What is an example of directional selection?

A population of insects developing resistance to a pesticide, resulting in an increase in the frequency of resistant individuals. (B) Signup and view all the answers

How does natural selection ultimately lead to evolution?

Natural selection favors individuals with traits that increase reproductive success, leading to changes in the genetic makeup of a population over time. (B) Signup and view all the answers

Study Notes

Chapter 23: Systematic, Phylogenies, and Comparative Biology

Systematics
- All organisms share many characteristics (cells, DNA, physical traits, metabolism, ATP)
- Difficult to determine close relationships
Branching Diagrams
- Show relatedness among things
- Various ways to represent relationships
- Indicate who is more closely related to whom
Similarity and Evolution
- Similarity does not always predict evolutionary relationships
- Evolutionary rates can vary, some genes may evolve faster than others
- Evolution may not be unidirectional: e.g., manatees evolved from land to water, then back to water
- Convergent evolution is possible
- Question: How much time has passed since divergence influences similarity of species.
Cladistics
- Analyze ancestral traits and derived traits
- Ancestral characteristics are inherited from the most recent common ancestor of a group
- May not distinguish between individuals in the same group

Cladistics Methods

Ancestral vs. Derived Characters
- Presence of hair is a shared derived feature in mammals
- Traits being ancestral or derived can change depending on context
- Lung presence in mammals is an ancestral trait
Characters can be morphological, physiological, behavioral, and ecological
Other Cladistics Method Concepts
- Character states for example presence or absence of tail in vertebrates
- Using outgroups to create comparisons of groups
- Synapomorphy: A new derived trait of a group
- Symplesiomorphy: A shared ancestral trait in a group and an outgroup

Chapter 20: Evolutionary Change

Processes that lead to evolutionary change
- Natural selection affects allele frequencies

Population Genetics

Study of genes in populations
- Understanding genetic variations within populations
- Natural populations contain considerable genetic variation

Hardy-Weinberg Principle

This principle explains when populations do not evolve
Proportions of genotypes remain constant under certain conditions (no mutation, no gene flow, and no selection)
If these conditions aren't met, change in allele frequencies occurs showing a population is evolving
Agents of Evolutionary Change
- Mutation: Fundamental unit of change
- Natural Selection
Factors influencing evolution
- Gene flow
- Non-random mating
- Genetic drift
- Random allele frequency change

Evidence for Evolution

Beaks of Darwin's Finches
- Darwin collected finches from Galapagos Islands
- Studied beak diversity in relation to what they eat
- Beak shape as a result of food selection
Artificial Selection
- Changing species characteristics through breeding
- Examples in dogs, crops (e.g., brassicas), etc.

Chapter 21: Fossil Evidence

Fossil Evidence
- Organisms buried in sediment form fossils
Fossil age estimation
- Relative position to determine age (deeper = older)
- Isotopic dating to calculate precise age
- Potassium and Carbon dating methods
Evolutionary Transitions
- Evidence of transitions from one form to another
- Examples: lizards to birds, apes to humans
- Intermediate forms have been found
Anatomical Evidence
- Examining anatomical structures (similar structures = shared ancestor)
- Examples: comparing forelimbs in diverse organisms
Embryology
- Studying early stages of development
- Embryonic similarities in diverse organisms
Vestigial Structures
- Structures with reduced function, but still present
- Examples: human appendix, whale pelvis

Biogeography

Studying distribution of organisms and their relationships to their environment and evolution
Distribution patterns can reflect common ancestry

Chapter 23: Additional

Evolution by Natural Selection
- Natural selection: The differential survival and reproduction of organisms based on traits.
- Necessary conditions: variation, variation causes differences in offspring, genetic influence of variation
Fitness
- Measure of an organism's ability to survive and reproduce
- "Fittest" organisms have the greatest reproductive success
Sexual Selection
- Selection based on an organism's ability to attract mates
- Traits favored for mating may be detrimental for general survival
Selection types
- Stabilizing selection (favors average traits)
- Directional selection (favors one extreme)
- Disruptive selection (favors both extremes)

Chapter 23: Additional topics and selection

Types of Selection
- Stabilizing, directional, and disruptive selection
  - Selection types and how environmental pressures change the selection
Maintenance of Variation
- Frequency-dependent selection: The fitness of a phenotype depends upon its frequency within the population
  - Rare phenotypes can be favored, uncommon traits are favored
- Positive frequency-dependent selection: favors common traits, tends to reduce variations
- Negative frequency-dependent selection: rare traits are favored by selection, increases variability

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Description

Explore the concepts of systematic biology, phylogenies, and comparative biology in this engaging quiz. Understand the complexities of relationships among organisms through branching diagrams, the nuances of similarity and evolution, and delve into cladistics. Test your knowledge on how species relate and evolve over time.