Phylogeny and the Tree of Life

These flashcards cover key concepts related to phylogeny and the evolution of life as presented in the lecture notes.

What is phylogeny?

The evolutionary history of a species or group of related species.

What does systematics focus on?

Classifying organisms and determining their evolutionary relationships.

What is the purpose of a phylogenetic tree?

To represent a hypothesis about the evolutionary history of a group of organisms.

Who instituted binomial nomenclature?

Carolus Linnaeus.

What does binomial nomenclature refer to?

A two-part format of scientific names for organisms.

What do common names like 'monkey' cause in biology?

Confusion, as they can refer to more than one species.

What are taxa in biological classification?

Named groups at any level of hierarchy.

What is a monophyletic group?

It consists of an ancestral species and all its descendants.

What are sister taxa?

Groups that share a common ancestor not shared by any other group.

What is homology?

Similarity due to shared ancestry.

What distinguishes analogy from homology?

Analogy is similarity due to convergent evolution.

What is cladistics?

An approach to systematics that groups organisms based on common ancestry.

What are shared derived characters?

Evolutionary novelties unique to a particular clade.

How does a phylogenetic tree represent evolutionary relationships?

By showing branch points that represent common ancestors.

What is an outgroup in phylogenetic studies?

A species or group of species closely related to, but not part of, the ingroup.

What do molecular clocks help estimate?

The absolute time of evolutionary change.

What’s an example of a shared ancestral character?

A backbone in mammals, which does not distinguish them from other vertebrates.

What is maximum parsimony in phylogenetics?

The assumption that the simplest explanation with the fewest evolutionary events is the most likely.

Why do DNA changes document evolution?

Because DNA is common to all life and changes reflect evolutionary history.

What do phylogenetic trees with proportional branch lengths represent?

Branch lengths that reflect the number of genetic changes in each lineage.

What is the three-domain system?

The classification of life into Bacteria, Archaea, and Eukarya.

What is horizontal gene transfer?

A process by which genes are transferred from one genome to another.

Why are molecular clocks not perfect?

Some genes evolve at irregular rates and may not mark time precisely.

What does the term 'clade' refer to in phylogenetics?

A group of species that includes an ancestral species and all its descendants.

What issue did phylogenies based on genetic data reveal about traditional classifications?

They showed that some prokaryotes differ as much from each other as they do from eukaryotes.

What are orthologous genes?

Homologous genes that result from a speciation event.

What are paralogous genes?

Homologous genes found within the same genome due to gene duplication.

Why is it important to distinguish homology from analogy in phylogenetic studies?

To accurately infer evolutionary relationships among organisms.

What does a phylogenetic tree depict?

Hypotheses about the evolutionary ancestry of organisms.

How does shared characters aid in phylogeny construction?

They help to infer evolutionary relationships based on common ancestry.

What can misinterpreting phylogenetic trees lead to?

Incorrect assumptions about species evolution and relationships.

What evidence do molecular comparisons provide?

They aid in deducing relatedness between different organisms.

What is a key limitation of molecular clocks?

The rate of useful genes may vary among different organisms.

What has shaped our understanding of the tree of life?

New data from genetic analysis and molecular studies.

What is the role of fossil data in phylogenetics?

It helps place branch points in the context of geological time.

What is the significance of distinguishing characters shared with outgroups?

It helps differentiate between shared derived and shared ancestral characters.

Why do some phylogenetic trees differ?

Different trees may arise from different genes showing divergent relationships.

What indicates that two species might be closely related?

Similar gene sequences despite differences in appearance.

What does the backbone represent in mammalian evolution?

A shared ancestral character that does not distinguish mammals from other vertebrates.

How do molecular comparisons track evolutionary relationships?

By analyzing DNA sequences for similarities and differences.

What are two types of evolutionary trees based on gene data?

Trees based on molecular clocks and trees based on maximum likelihood.

What does convergence in evolution imply?

Unrelated species develop similar traits due to similar environmental pressures.

What is the relationship between the three domains and the evolution of life?

The three-domain system reflects significant evolutionary divergence in prokaryotes and eukaryotes.

What does the presence of similar morphology suggest?

It may indicate a common ancestry, but further molecular analysis is needed.

What does the term 'evolutionary novelty' refer to?

A new characteristic that arises within a clade.

What is the effect of gene duplication on evolution?

It increases the number of genes, providing opportunities for evolutionary change.

What are some limitations of using morphology to infer phylogeny?

Phenotypic similarities can arise from convergent evolution.

What technique helps visualize evolutionary relationships on a timeline?

Phylogenetic trees with proportional branch lengths.

How are shared derived characters used in constructing phylogenetic trees?

To hypothesize the evolutionary relationships among organisms.

What is a key characteristic of polyphyletic groups?

They include distantly related species without their most recent common ancestor.

What is an example of a shared derived character in mammals?

Hair, which is unique to mammals.