Classification and Phylogeny Flashcards

Questions and Answers

What is the definition of phylogeny?

Scientific study of biological diversity

Theory and practice of classifying organisms

History of descent of a group of taxa from their common ancestor (correct)

Field concerned with identifying evolutionary relationships

What does systematics study?

Biological diversity and evolutionary history (correct)

Organisms' physical structures

Relationship between genes and traits

Distribution of species across environments

What is taxonomy?

Theory and practice of classifying organisms

Darwin was the first to recognize that the systematic hierarchy approximates evolutionary history.

True Signup and view all the answers

What does phylogenetic systematics focus on?

Understanding evolutionary relationships among living and extinct life Signup and view all the answers

What does evolutionary theory explain about similarity among individuals or species?

Attributable to common descent or inheritance Signup and view all the answers

What are characters in biological classification?

Heritable attributes or features of an organism used for classification Signup and view all the answers

Which character state is a modified version of a primitive condition?

Derived Signup and view all the answers

Define plesiomorphic characters.

Ancestral traits Signup and view all the answers

Define apomorphic characters.

Derived traits Signup and view all the answers

What are synapomorphic traits?

Traits defining a group in relation to its nearest relatives Signup and view all the answers

What are autapomorphic traits?

Derived traits found only in members of a particular group Signup and view all the answers

What does homology signify?

Relationships of common descent between any entities Signup and view all the answers

What basic assumption does cladistics rely on?

Members of a group share a common evolutionary history Signup and view all the answers

What are apomorphies?

Unique features shared by related groups of organisms Signup and view all the answers

Define synapomorphies.

Shared derived characteristics Signup and view all the answers

What is a clade?

Group of two or more taxa or DNA sequences including their common ancestor and descendants Signup and view all the answers

What is a node in taxonomy?

Taxonomic unit, either an existing species or an ancestor Signup and view all the answers

What does a branch represent in a phylogenetic tree?

Relationship between the taxa of descent and ancestry Signup and view all the answers

What does branch length indicate?

Number of changes that have occurred in the branch Signup and view all the answers

What is a distance scale in phylogenetics?

Scale that represents the number of differences between organisms or sequences Signup and view all the answers

What does the root of a phylogenetic tree represent?

The common ancestor of all taxa Signup and view all the answers

What is meant by topology in phylogenetic contexts?

The branching patterns of the tree Signup and view all the answers

What is an Operational Taxonomic Unit (OTU)?

A taxon Signup and view all the answers

Study Notes

Phylogeny and Systematics

Phylogeny refers to the evolutionary history of a taxon, tracing descent from common ancestors.
Systematics is the scientific study focused on biological diversity and the grouping of organisms based on evolutionary history.
Taxonomy involves the theoretical and practical aspects of classifying organisms.

Historical Figures

Charles Darwin recognized that the hierarchical classification system was a rough guide to evolutionary history.
Willi Hennig emphasized that systematics should accurately reflect known evolutionary lineages.

Key Concepts in Evolution

Evolutionary theory posits that similarities among species arise from common descent, influencing phylogenetic relationships.
Understanding evolutionary relationships helps trace the historical lineage among organisms and their genetic attributes.

Characters in Classification

Characters are heritable features used to identify, differentiate, and classify taxa, sourced from morphological, behavioral, developmental, and molecular data.
Ancestral characters (plesiomorphic) are traits from distant ancestors, while derived characters (apomorphic) are modified versions of these traits.

Trait Categories

Synapomorphic traits are shared derived characteristics that distinguish a group from its closest relatives, such as the carnassial teeth in cats and dogs.
Autapomorphic traits are unique derived characteristics found within a particular group, like hair in mammals.

Classification Methods

Homology indicates a relationship of common descent among entities without specifying the evolutionary details.
Cladistics classifies organisms based on their branching patterns, reflecting their common ancestry.

Cladistics and Phylogenetic Relationships

Apomorphies are unique features that characterize related organism groups, distinct from their distant ancestors.
Synapomorphies are shared derived traits that define closer relationships within a clade.

Clades and Their Structure

A clade is a group containing two or more taxa along with their common ancestor and all descendants.
Nodes represent taxonomic units, which can be existing species or shared ancestors.

Branching and Evolutionary Changes

Branches illustrate relationships between taxa, indicating descent and ancestry.
Branch length signifies the number of evolutionary changes that have occurred along that line.
A distance scale measures the differences between organisms or their genetic sequences.

Root and Topology

The root is the common ancestor of all taxa within a phylogenetic tree.
Topology describes the branching patterns and their configurations in the evolutionary tree.

Operational Taxonomic Unit (OTU)

An Operational Taxonomic Unit is defined as a taxon at any level, often used for data analysis in systematics.

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Description

Test your knowledge on the key concepts of classification and phylogeny with this set of flashcards. Learn about phylogeny, systematics, taxonomy, and the contributions of Darwin. Perfect for biology students looking to reinforce their understanding of evolutionary relationships.