Ch 26 - Phylogeny and Systematics Flashcards

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Questions and Answers

Which of the following correctly defines taxonomy?

The study of diversity and differentiation of organisms

Discovering, describing, and naming organisms (correct)

Classification by evolutionary relationships

A scientific discipline that uses nucleic acids to infer relationships

What is systematics?

Study of diversity and differentiation of organisms and relationships between organisms.

Define phylogeny.

Classification by evolutionary relationships.

Why is it important to distinguish between homology and analogy?

Homology refers to similarity due to shared ancestry, while analogy refers to similarity due to convergent evolution. Signup and view all the answers

Explain why bird and bat wings are homologous but analogous.

They are homologous as forelimbs due to a common ancestor, but analogous as wings because of adaptation for flying. Signup and view all the answers

List some problems associated with using common names.

Common names can vary with language and locale, developed for common species only, and may have several names for the same species. Signup and view all the answers

What is binomial nomenclature?

The two-part format of the scientific name of an organism, consisting of genus and species. Signup and view all the answers

Describe hierarchical classification.

A system for grouping species into increasingly broad categories. Signup and view all the answers

List the major taxonomic categories from most to least inclusive.

Domains, Kingdom, Phylum, Class, Order, Family, Genus, Species. Signup and view all the answers

Define a clade.

A group of species that includes an ancestral species and all of its descendants. Signup and view all the answers

Which of the following is a characteristic of a monophyletic group?

Includes all descendants of a common ancestor. Signup and view all the answers

Differentiate between shared primitive characters and shared derived characters.

Shared primitive characters originated in an ancestor not part of the clade, while shared derived characters are unique to a particular clade. Signup and view all the answers

How can shared derived characters be used to construct a phylogeny diagram?

They help identify the clades in which each characteristic appeared, allowing inference of evolutionary relationships. Signup and view all the answers

How does outgroup comparison help distinguish between ancestral and derived characters?

By comparing outgroups, one can determine which characters were derived at various branch points in evolution. Signup and view all the answers

What is the principle of maximum parsimony?

It looks for the simplest explanation consistent with the facts, requiring the fewest evolutionary events. Signup and view all the answers

Explain maximum likelihood in phylogeny reconstruction.

It reflects the most likely sequence of evolutionary events based on DNA changes over time. Signup and view all the answers

Why does a phylogenetic diagram represent a hypothesis?

It shows how closely related different species are and illustrates their evolutionary relationships. Signup and view all the answers

Differentiate between orthologous and paralogous genes.

Orthologous genes are found in different species due to speciation; paralogous genes are found within the same genome due to gene duplication. Signup and view all the answers

Explain how gene duplication has led to families of paralogous genes.

Gene duplication increases gene numbers, allowing paralogous genes to diverge within their clade. Signup and view all the answers

What is cladistics?

A method of classification according to the proportion of measurable characteristics shared. Signup and view all the answers

What is a cladogram?

A branching diagram showing the cladistic relationships between species. Signup and view all the answers

What is homoplasy?

A character shared by a set of species but not present in their common ancestor. Signup and view all the answers

Define ingroup.

An exclusive, typically small group of people with a shared interest or identity. Signup and view all the answers

What is an outgroup?

A group of organisms not belonging to the group whose evolutionary relationships are being studied. Signup and view all the answers

Define molecular systematics.

A discipline that uses nucleic acids or other molecules in different species to infer relationships. Signup and view all the answers

What is a phylogenetic tree?

A diagram that depicts the lines of evolutionary descent of species from a common ancestor. Signup and view all the answers

What is a taxon?

A taxonomic group of any rank, such as a species, family, or class. Signup and view all the answers

Study Notes

Taxonomy, Systematics, and Phylogeny

Taxonomy: Involves discovering, describing, and naming organisms (nomenclature).
Systematics: Examines organism diversity, differentiation, and relationships.
Phylogeny: Focuses on classifying organisms based on evolutionary relationships.

Homology vs. Analogy

Homology: Similarities stemming from a shared ancestry; indicates evolutionary connections.
Analogy: Similar traits due to convergent evolution, not shared ancestry.

Wings of Birds and Bats

Homologous: Both originated from a common forelimb ancestor but could not fly.
Analogous: Adapted similar structures for flight through different evolutionary paths.

Common Names Issues

Older terms can vary with language and region.
Common names typically developed for familiar species only.
A single species may have multiple common names, creating confusion.

Linnaean System Characteristics

Binomial Nomenclature: Two-part naming format using genus and species, italicized with specific capitalization rules (e.g., Homo sapiens).
Hierarchical Classification: Organisms grouped into broad categories, with increasing specificity (e.g., Leopard - Panthera pardus belongs to Panthera genus).

Taxonomic Hierarchy

Domains: Most inclusive category.
Animal Kingdom: Includes Animalia.
Phylum: Chordata.
Class: Mammalia.
Order: Primates.
Family: Hominidae.
Genus: Homo.
Species: H. sapiens.

Clades and Groupings

Clade: A group of species including an ancestor and all descendants.
Monophyletic Group: Ancestral species and all its descendants, recognized as legitimate taxa.
Paraphyletic Group: Includes an ancestor but not all descendants.
Polyphyletic Group: Lacks the common ancestor of its members.

Character Types in Phylogeny

Shared Primitive Characters: Traits common to a clade but originating from an ancestor outside the clade.
Shared Derived Characters: Unique evolutionary novelties specific to a clade.

Constructing Phylogeny Diagrams

Shared derived characters identify clades and depict evolutionary relationships.

Outgroup Comparison

Compares outgroups to identify derived characters at branch points in evolution.

Phylogenetic Reconstruction Principles

Maximum Parsimony: Seeks the simplest explanation with the fewest evolutionary events.
Maximum Likelihood: Reflects the most probable sequence of events based on DNA change rules.

Phylogenetic Diagrams

Represent hypotheses regarding evolutionary relationships among species.

Gene Types

Orthologous Genes: Found in different species due to speciation.
Paralogous Genes: Found within the same genome due to gene duplication.

Gene Duplication Impact

Increases gene number, allowing diversification of paralogous genes within a clade.

Cladistics and Cladogram

Cladistics: Classifying organisms based on shared measurable characteristics.
Cladogram: A branching diagram showing cladistic relationships among species.

Homoplasy

Character shared by species not present in their common ancestor, often through convergence (e.g., independent evolution of eyes).

Ingroup vs. Outgroup

Ingroup: A small group with shared interests or characteristics.
Outgroup: Organisms outside the group being studied for evolutionary relationships.

Molecular Systematics

Utilizes nucleic acids or molecules to infer species' evolutionary relationships.

Phylogenetic Tree

A diagram depicting lines of descent among species or genes from a common ancestor.

Taxon Definition

Any taxonomic group, regardless of rank, such as species, family, or class.

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Description

Test your knowledge on key concepts of phylogeny and systematics with these flashcards. Learn to differentiate between taxonomy, systematics, and phylogeny, and understand the importance of distinguishing homology from analogy in classification. Perfect for students studying biology and evolution.