Biology Chapter on Adaptation and Variation

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Questions and Answers

What is the main principle behind choosing a cladogram according to the Principle of Parsimony?

The simplest cladogram will be made. (correct)

The cladogram with the longest branches.

The cladogram that includes all potential evolutionary changes.

The cladogram that represents the most complex relationships.

Which type of group is characterized by containing all descendants from a single common ancestor?

Polyphyletic group

Non-monophyletic group

Monophyletic group (correct)

Paraphyletic group

Which of the following represents a trait that may appear homologous in isolation but is a result of convergent evolution?

Fins of sharks and dolphins

Forelimbs of mammals and reptiles

Flippers of whales and penguins

Wings of bats and insects (correct)

What differentiates phylograms from cladograms?

Phylograms represent time while cladograms do not. Signup and view all the answers

Which method adjusts for the likelihood that a character change is accidental when constructing phylogenetic trees?

Maximum Likelihood Signup and view all the answers

What is one of the five properties that suggest species might change over time?

Many individuals of each species are born than can possibly survive Signup and view all the answers

Why is inheritance important to the evolutionary process?

It enables the connection of selection outcomes across generations Signup and view all the answers

What defines natural selection in the context of evolution?

The process by which species adapt to their environment Signup and view all the answers

Which of the following describes microevolution?

Small evolutionary changes within a species Signup and view all the answers

How do snout proportions in dogs facilitate evolutionary change compared to cats?

Dogs show a wide range of existing variation in snout lengths Signup and view all the answers

What is meant by the term 'struggle for existence'?

Individuals must compete due to resource limitations Signup and view all the answers

Which statement accurately reflects the concept of evolution?

It is essentially the descent with modification of species Signup and view all the answers

What role does phenotypic variation play in natural selection?

It allows for selection based on advantageous traits Signup and view all the answers

What is the defining characteristic of sympatric speciation?

It occurs within a population without geographic isolation. Signup and view all the answers

Which is an example of sympatric speciation?

Fruit flies evolving in response to different food sources. Signup and view all the answers

What distinguishes prezygotic barriers from postzygotic barriers?

Prezygotic barriers prevent mating; postzygotic barriers affect the hybrid offspring. Signup and view all the answers

How does reinforcement work in the context of hybrid zones?

It leads to stronger reproductive barriers through natural selection. Signup and view all the answers

Why is sympatric speciation considered rare?

Interbreeding tends to occur among individuals of the same species. Signup and view all the answers

What is a postzygotic barrier exemplified by the mule?

Sterility of offspring from different species. Signup and view all the answers

Which factor supports the fitness of a new species in a local environment?

Development of reproductive barriers to prevent interbreeding. Signup and view all the answers

What is the main difference between generalists and specialists over long time scales?

Specialists perform better in restricted environments, while generalists are average in many. Signup and view all the answers

What is the term for when traits that are not directly selected can be carried along with selected traits in evolution?

Evolutionary Hitchhiking Signup and view all the answers

Which type of selection favors extreme phenotypes rather than intermediate ones?

Disruptive Selection Signup and view all the answers

In which situation can natural selection occur without causing evolution?

When stabilizing selection occurs Signup and view all the answers

What is one major way that new mutations arise in the genome?

Environmental damage Signup and view all the answers

What mechanism refers to a drastic reduction in population size, leading to a loss of genetic diversity?

Bottleneck Effect Signup and view all the answers

Which type of selection occurs when one phenotype is favored over others in a continuous gradient?

Directional Selection Signup and view all the answers

What is the effect of a fast mutation rate on the evolution of drug resistance in viruses?

Facilitates rapid adaptation Signup and view all the answers

Which of the following mechanisms is NOT a way that evolution can occur without natural selection?

Stabilizing Selection Signup and view all the answers

What significant event led to a dramatic increase in atmospheric oxygen and the emergence of eukaryotes?

The Great Oxygenation Event Signup and view all the answers

Why might the Great Oxygenation Event be referred to as the Great Poisoning?

Oxygen became essential and inhibited biochemical processes. Signup and view all the answers

What best describes multicellularity?

The presence of more than one type of cell. Signup and view all the answers

What are stromatolites primarily formed by?

The binding and cementation by microorganisms. Signup and view all the answers

Which of these is correctly associated with the planet Theia?

A proto-planet that collided with Earth to form the Moon. Signup and view all the answers

What is a characteristic of Snowball Earth events?

Freezing conditions that may lead to ocean solidification. Signup and view all the answers

Which of the following can be attributed to the Faint Early Sun phenomenon?

Increased luminosity by ~50% over four billion years. Signup and view all the answers

What distinguishes slime molds from other multicellular organisms?

They alternate between single-celled and multicellular states. Signup and view all the answers

Study Notes

Adaptation and Variation

Adaptation enhances species' fitness through traits that improve survival and reproduction.
Variation is often regarded as random:
- Random in regards to the organism's needs; mutations appear without intention.
- Specific variations (e.g., limbs) are constrained by genetic possibilities.
- Random variation in traits like human height but no random variation in limb count.

Selection and Evolution

Identifying targets of selection can be challenging due to evolutionary hitchhiking:
- Non-selected traits can be carried along with selected traits during evolution.
Natural selection can occur without evolution:
- Example: Stabilizing selection favors intermediate phenotypes, maintaining the status quo without leading to evolutionary change.

Types of Selection

Stabilizing selection: Favors middle phenotypes.
Directional selection: Favors one extreme phenotype.
Disruptive selection: Favors extreme phenotypes at both ends.

Sexual Selection

Selection focused on mating access is termed sexual selection, influencing traits related to reproductive success.

Evolution Without Selection

Evolution can occur without selection through:
- Genetic Drift: Random changes in allele frequencies.
- Bottleneck Effect: Loss of genetic diversity due to a significant reduction in population size.
- Founder Effect: Genetic variation resulting from a small population colonizing a new area.

Mechanisms of Evolutionary Change

Adaptive changes driven by selection:
- Includes disruptive, directional, and sexual selection.
Non-adaptive changes driven by chance:
- Includes genetic drift, bottleneck effect, and founder effect.
Evolution can also be driven by new mutations and genetic flow.

Mutation and Drug Resistance

Most mutations arise from DNA replication errors or environmental damage.
Rapid mutation rates enable faster adaptation, allowing pathogens to quickly develop drug resistance.

Key Properties of Evolution

Five properties lead to the expectation of species changing over time:
- Overproduction, struggle for existence, phenotypic variability, dependence of existence on phenotypes, and heritability.
Inheritance links outcomes from one generation to the next, essential for evolutionary processes.

Speciation Concepts

Sympatric speciation occurs within a population without geographical barriers, exemplified by fruit flies adapting to different food sources.
Reinforcement in hybrid zones occurs when organisms preferentially mate within their own zone despite the ability to interbreed.

Reproductive Barriers

Prezygotic barriers occur before fertilization (e.g., differences in mating behaviors).
Postzygotic barriers occur after fertilization (e.g., mules are sterile hybrids).

Evolutionary Tension

Specialists excel in specific environments but have limited range; generalists thrive in many but are average in any single environment.

Phylogenetics

Phylograms and phylogenies differ from cladograms in that they reflect changes over time rather than mere relationships.
Synapomorphies indicate shared ancestry, while homoplasies appear similar but do not indicate common ancestry (e.g., bat and insect wings).

Major Evolutionary Events

The Great Oxygenation Event elevated atmospheric oxygen levels and drastically changed ecological dynamics, considered by some as the "Great Poisoning" for its toxic effects on anaerobic organisms.
The emergence of multicellularity and various independent multicellular organisms marks significant evolutionary transitions.

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Description

This quiz explores the concepts of adaptation and variation in species. It examines how variation is random in terms of the needs of organisms but is constrained by possible genetic changes. Test your understanding of these fundamental principles in biology.