Classification and Phylogeny Flashcards

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Questions and Answers

What does 'phylogeny' refer to?

The study of cell structures
The evolutionary history of a species or group of species (correct)
A method of grouping organisms based on physical traits
The classification of living organisms

What is 'cladistics'?

An outdated classification method
A system that uses shared derived characters for grouping (correct)
A random method of classification
A classification based on structural similarities

What is a clade?

A group of organisms that are monophyletic.

What is the definition of 'class' in biological taxonomy?

A major category ranking above the order and below the phylum. Signup and view all the answers

What is the taxonomic definition of 'domain'?

A taxonomic group of one or more kingdoms. Signup and view all the answers

What does 'family' refer to in taxonomy?

A taxonomic group of similar related genes that is smaller than a genus and larger than an order. Signup and view all the answers

What is a 'genus'?

A taxonomic group of closely related species with a common ancestor. Signup and view all the answers

What is an 'ingroup'?

A species or group of species whose evolutionary relationships we seek to determine. Signup and view all the answers

What is an 'outgroup'?

A species or group of species known to have diverged before the lineage being studied. Signup and view all the answers

What does 'maximum likelihood' mean in systematics?

A principle stating the most likely sequence of evolutionary events should be considered. Signup and view all the answers

What is 'maximum parsimony'?

A principle stating the simplest explanation that is consistent with the facts should be investigated first. Signup and view all the answers

What does 'monophyletic' mean?

Pertains to a group of taxa that consists of a common ancestor and all its descendants. Signup and view all the answers

What is 'paraphyletic'?

A group of taxa that includes a common ancestor and some, but not all, of its descendants. Signup and view all the answers

What does 'polyphyletic' indicate?

A group of taxa derived from two or more different ancestors. Signup and view all the answers

What is a 'phylum' in biological classification?

The taxonomic category above class. Signup and view all the answers

What determines which domain an organism is in?

Type of cell (eukaryote or prokaryote), number of cells (unicellular or multicellular), chemical makeup. Signup and view all the answers

What are the criteria for determining which kingdom an organism belongs to?

Cell type, the number of cells in their body, and ability to make food. Signup and view all the answers

Why has the Old Kingdom system proved to be impractical?

The number of kingdoms kept changing, and early classification was based solely on visual observation. Signup and view all the answers

How has DNA technology changed classification?

It gives scientists an accurate indicator of similar ancestry within species. Signup and view all the answers

What is the relationship between taxonomy and phylogeny?

Taxonomy names and classifies diverse life forms; phylogeny determines evolutionary relationships. Signup and view all the answers

How is the Linnaean hierarchy used to classify organisms?

It is based on similarities in physical traits. Signup and view all the answers

How are organisms classified using binomial nomenclature?

Combines two names: the first part is the genus, and the second part is the specific epithet. Signup and view all the answers

How should an organism's scientific name be written?

It should be italicized, with the genus name capitalized and the specific epithet not capitalized. Signup and view all the answers

What is the fundamental approach when making and reading a cladogram?

Identify the outgroup as the most different and ingroups with similar traits. Signup and view all the answers

What is the difference between mono-, poly-, and paraphyletic groups?

Monophyletic: one ancestor; Polyphyletic: multiple ancestors; Paraphyletic: includes some descendants but not all. Signup and view all the answers

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Study Notes

Phylogeny and Cladistics

Phylogeny refers to the evolutionary history of species or groups, illustrating their developmental pathways.
Cladistics is a classification method that groups organisms based solely on shared derived characteristics and their ancestry.

Taxonomic Hierarchy

Clade: A monophyletic group including a common ancestor and all its descendants.
Domain: The highest taxonomic rank, encompassing one or more kingdoms based on fundamental differences in cell types.
Phylum: A major taxonomic category higher than class and lower than domain.

Taxonomic Categories

Class: Ranks above order and below phylum in biological classification.
Family: Groups closely related genera, smaller than a genus and larger than an order.
Genus: A taxonomic group consisting of closely related species sharing a common ancestor.

Ingroup and Outgroup

Ingroup: The species or group being studied to determine evolutionary relationships.
Outgroup: A related species or group that diverged earlier, serving as a point of reference for the ingroup.

Classification Principles

Maximum Likelihood: A method in systematics focusing on the most probable sequence of evolutionary changes when evaluating different phylogenetic hypotheses.
Maximum Parsimony: Prioritizes the simplest explanation that accounts for observed data when considering multiple explanations.

Cladistic Group Definitions

Monophyletic: Contains a single common ancestor and all its descendants.
Paraphyletic: Includes a common ancestor but not all its descendants.
Polyphyletic: Composed of organisms from two or more different ancestors.

Kingdom and Domain Determinants

Domain classification is based on:
- Cell type (eukaryote or prokaryote)
- Number of cells (unicellular or multicellular)
- Chemical makeup
Kingdom classification considers:
- Cell type
- Cell number
- Nutritional methods (autotroph vs. heterotroph)

Historical Classification Challenges

The Old Kingdom system was limited due to fluctuating kingdom numbers and reliance on visual observations, leading to inaccuracies.

Impact of DNA Technology

Advances in DNA technology enhance classification accuracy by reflecting genetic similarities and evolutionary relationships among species.

Taxonomy vs. Phylogeny

Taxonomy is focused on naming and classifying life forms, whereas phylogeny studies the evolutionary connections among them.

Linnaean Hierarchy

The Linnaean system uses physical traits to classify organisms into hierarchical categories.

Binomial Nomenclature

Uniquely identifies species using two names: the first (genus) capitalized, and the second (specific epithet) in lowercase; both names are italicized.

Cladogram Analysis

A cladogram illustrates evolutionary relationships:
- Outgroup represents the most distantly related species.
- Ingroup displays species with more similar traits.

Differences in Phylogenetic Group Types

Monophyletic: All members descend from a single ancestor.
Polyphyletic: Includes unrelated organisms from multiple ancestors.
Paraphyletic: Excludes some descendants of a common ancestor.

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