Lecture 10: Phylogenetics I

These flashcards cover key concepts such as phylogenetics, classification systems, traits, and evolutionary relationships discussed in the lecture.

What is the purpose of phylogenetics?

To reconstruct the evolutionary history of species and understand their pattern of descent.

What are the main components of a phylogenetic tree?

Root, nodes, branches, branch tips, and outgroup.

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

An evolutionary innovation or derived trait.

Define 'plesiomorphy.'

A pre-existing or ancestral trait.

What are synapomorphies?

Shared evolutionary innovations or derived traits.

What is meant by the term 'homology'?

Shared traits that are a result of common ancestry.

How do convergent and divergent evolution differ?

Convergent evolution is when unrelated species develop similar traits due to similar environmental pressures, while divergent evolution occurs when closely related species evolve different traits due to differing selective pressures.

What is the function of outgroup analysis in phylogenetics?

To help infer the ancestral state of traits and ensure the ingroup is monophyletic.

What is the importance of parsimony analysis in building phylogenies?

It aims to find the tree that requires the fewest evolutionary changes.

What is a vestigial trait?

A trait that serves no known current function but remains because it is not costly to retain or may be on its way out.

What distinguishes a phylogeny from a pedigree?

A phylogeny represents evolutionary relationships of populations over time, while a pedigree represents relationships among individuals and expands backward in time.

What does 'homoplasy' mean in the context of phylogenetics?

Similarity in traits not due to common ancestry, often arising from convergent evolution.

What role do derived traits play in phylogenetic analysis?

They are used to define relationships and branching patterns in a phylogenetic tree.

What is a taxon?

A group of related organisms placed at a branch tip in a phylogenetic tree.

Define 'synapomorphy.'

A shared derived trait that is used to help classify organisms based on evolutionary relationships.

How can one distinguish between homology and homoplasy?

By using methods such as comparative embryology, fossil records, and agreement with other phylogenetic hypotheses.

What is a monophyletic group?

A group of organisms that includes an ancestor and all its descendants.

Define 'paraphyletic group.'

A group that includes a common ancestor but not all its descendants.

What is a polyphyletic group?

A group formed from multiple ancestors but does not include the most recent common ancestor.

What is meant by morphological traits in phylogenetics?

Physical characteristics or features used to classify organisms.

Describe molecular phylogenetics.

The analysis of molecular data, such as DNA sequences, to understand evolutionary relationships.

What is a cladogram?

A diagram that depicts the relationships between organisms based on shared derived characteristics.

What is an evolutionary lineage?

A series of species each of which is considered to have evolved from its predecessors.

What role do mutations play in evolution?

They create genetic variability, which can lead to new traits that may affect survival and reproduction.

Define species concept in phylogenetics.

A way to define and categorize species based on various criteria, such as morphological, ecological, or genetic differences.

What is the significance of using a molecular clock in phylogenetics?

A molecular clock uses mutation rates to estimate the time of divergence between species based on genetic data.

Explain the concept of adaptive radiation.

Adaptive radiation is the rapid evolution of diversely adapted species from a common ancestor to fill various ecological niches.

What is the role of phylogenetic trees in understanding biodiversity?

Phylogenetic trees illustrate the evolutionary relationships among species, helping to visualize the diversity of life and its history.

What is meant by 'parallel evolution'?

Parallel evolution occurs when related species evolve similar traits independently due to similar selection pressures in comparable environments.

What is a key innovation in evolutionary terms?

A key innovation is a novel trait that allows a species to exploit new resources or environments, leading to increased diversification.

Define 'co-evolution.'

Co-evolution refers to the reciprocal evolutionary changes in interacting species, such as predators and prey or host and parasite.

What does 'phylogeography' study?

Phylogeography studies the historical processes that may be responsible for the geographic distributions of individual species or populations.

What is the principle of maximum likelihood in phylogenetics?

The principle of maximum likelihood estimates the best phylogenetic tree by assessing the probability of observed data given different tree hypotheses.