Biology 2 Chapter 23 Flashcards

Questions and Answers

What does a phylogeny represent?

A statement about an organism

A random classification

Hypothesis about patterns of relationship among species (correct)

Only extinct species

What is systematics?

Reconstruction and study of evolutionary relationships.

Why does phenotypic similarity not necessarily indicate close evolutionary relationships?

Rates of evolution vary and evolution is not always divergent.

What is the difference between ancestral and derived similarities?

Derived characteristic is inherited from the most recent common ancestor of an entire group, while an ancestral characteristic arose prior to the common ancestor of the group. Signup and view all the answers

Why do only shared, derived characters indicate close evolutionary relationships?

They are determined from comparison to a group known to be closely related, termed an outgroup. Signup and view all the answers

How is a cladogram constructed?

It minimizes the amount of character evolution required. Signup and view all the answers

Differentiate among monophyletic, paraphyletic, and polyphyletic groups.

All of the above. Signup and view all the answers

What does the phylogenetic species concept emphasize?

The possession of shared derived characters. Signup and view all the answers

Explain the importance of homoplasy for interpreting patterns of evolutionary change.

Homologous traits are derived from the same ancestral character states, while homoplastic traits are not. Signup and view all the answers

How can phylogenetic trees reveal the existence of homoplasy?

They examine the distribution of traits among species in the context of their phylogenetic relationships. Signup and view all the answers

How can a phylogenetic tree indicate the timing of species diversification?

By correlating phylogenetic branching with known evolutionary events. Signup and view all the answers

How can phylogenetic analysis help identify patterns of disease transmission?

By tracking the evolution of disease strains, uncovering sources and progression. Signup and view all the answers

What is convergent evolution?

Similar characters not derived from common ancestry. Signup and view all the answers

Define synapomorphy.

Derived character shared by clade members. Signup and view all the answers

What is homoplasy?

A shared character state that has not been inherited from a common ancestor. Signup and view all the answers

What is the principle of parsimony?

The cladogram that requires the fewest number of evolutionary changes is favored. Signup and view all the answers

What is classification in the context of evolutionary history?

How we place species and higher groups into the taxonomic hierarchy. Signup and view all the answers

What does the biological species concept (BSC) focus on?

Reproductive isolation. Signup and view all the answers

Define homologous structures.

Derived from the same ancestral source. Signup and view all the answers

What are analogous structures?

Similar function due to similar selection pressures. Signup and view all the answers

What is homoplastic convergence?

Evolving separately due to adaptations to the environment. Signup and view all the answers

What are plesiomorphies?

Ancestral states. Signup and view all the answers

What are symplesiomorphies?

Shared ancestral states. Signup and view all the answers

Which characteristics do all organisms share?

Composed of one or more cells Signup and view all the answers

What did Darwin envision about all species?

All species were descended from a single common ancestor. Signup and view all the answers

__________ may not accurately predict evolutionary relationships.

Similarity Signup and view all the answers

In a cladogram, what part is a derived feature?

Is only shared by part of the cladogram. Signup and view all the answers

In a cladogram, what part is an ancestral feature?

Is shared by the whole group. Signup and view all the answers

What is an outgroup comparison?

Species or group of species that is closely related to, but not a member of the group. Signup and view all the answers

What is the simian immunodeficiency virus (SIV)?

Found in 36 species of primates and does not usually cause illness. Signup and view all the answers

Study Notes

Phylogeny and Systematics

Phylogeny represents a hypothesis about relationships among species, illustrated with a cladogram or phylogenetic tree.
Systematics is the reconstruction and study of evolutionary relationships among organisms.

Phenotypic Similarity

Phenotypic similarity does not always indicate close evolutionary relationships due to varying rates of evolution and non-divergent evolution patterns.

Ancestral vs. Derived Characteristics

Derived characteristics are inherited from the most recent common ancestor of a group, while ancestral characteristics predate that common ancestor.
Only shared derived characters indicate close evolutionary relationships, determined through comparisons with a closely related outgroup.

Cladograms

Cladograms are constructed to minimize the amount of character evolution required, reflecting evolutionary relationships accurately.

Taxonomic Groups

Monophyletic groups (clades) include the most recent common ancestor and all its descendants.
Paraphyletic groups include the common ancestor but not all descendants.
Polyphyletic groups do not include the common ancestor of all members.

Phylogenetic Species Concept (PSC)

PSC emphasizes shared derived characters and is controversial as it considers historical separation for character development; applicable to both sexual and asexual species.

Homoplasy

Homoplasy refers to traits that may have similar functions but did not arise from a common ancestral source, impacting the interpretation of evolutionary change.

Evolutionary Trees

Phylogenetic trees can reveal homoplasy by examining trait distribution among species within their evolutionary context.
Timing of species diversification can be inferred by correlating phylogenetic branching with known evolutionary events.

Disease Transmission

Phylogenetic analysis can track the evolution of disease strains, aiding in identifying sources and transmission patterns, exemplified by HIV studies.

Key Concepts and Terms

Convergent evolution results in similar traits not derived from a common ancestor.
Synapomorphy refers to a derived character shared by members of a clade.
The principle of parsimony favors cladograms with the fewest evolutionary changes.
Biological species concept (BSC) highlights reproductive isolation as a key factor in defining species.
Homologous structures arise from a common ancestral source, such as a dolphin's flipper and a horse's leg, while analogous structures serve similar functions due to similar selection pressures.
Homoplastic convergence describes traits evolving separately due to environmental adaptations, like plant conducting tubes.

Classification and Evolution

Classification involves placing species into a taxonomic hierarchy based on evolutionary history.
All organisms share traits such as cellular composition, metabolic activity, energy transfer via ATP, and hereditary information encoded in DNA.
Darwin's concept of "descent with modification" holds that all species have a common ancestor and experience evolutionary change.

Cladogram Features

In cladograms, derived features are shared by only part of the group while ancestral features are shared by the whole group.
Outgroup comparison involves studying species closely related to but not part of the main group to determine ancestral traits.

Simian Immunodeficiency Virus (SIV)

SIV is found in 36 species of primates and generally does not cause illness.

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Test your understanding of phylogenetics and systematics with these flashcards from Biology Chapter 23. Each card covers key concepts such as evolutionary relationships and the interpretation of phylogenetic trees. Perfect for reinforcing your knowledge in evolutionary biology.