Phylogenetics Flashcards
What are hybrid zones?
Areas or regions where different species with incomplete reproductive barriers mate and produce hybrids.
What are the three possible outcomes of hybrid zones?
- Reinforcement
- Fusion
- Stability
What happens in reinforcement?
The barriers for reproduction become stronger and the differences between the species are reinforced.
What happens in fusion?
The barriers for reproduction are weakened and the differences between the species are also weakened.
What happens in stability?
The barriers for reproduction remain intact.
What does the biological species concept emphasize?
Reproductive isolation
What is cladistics?
A way of organizing information according to similarities. In biology, it is used to assess what organisms are more similar to one another (we then assume this correlates with ancestry).
How are evolutionary relationships determined in the absence of DNA?
Through morphology: outward appearance (shape, structure, color, pattern) of an organism or taxon and its component parts.
What do cladistics reveal about evolution?
It identifies convergent evolution, allowing us to examine what happened in the fossil record.
What is a phylogenetic tree?
The mathematical structure used to depict the evolutionary history of a group of organisms or genes.
Do phylogenetic trees show similarities between organisms or historical relationships?
Historical relationships.
What is systematics?
The discipline that focuses on inferring the phylogenetic relationships of organisms and creating classifications based on their evolutionary histories.
What is homology?
Similarity arising from common ancestry.
What are homologous characters?
Characters present in a group of species due to shared ancestry.
What are analogous/homoplastic characters?
Characters present in certain species that have evolved independently. (convergent evolution)
In a phylogenetic tree, what is a branch point?
A branch point is where lineages diverge.
What is a polytomy?
An unresolved pattern of divergence.
What are shared ancestral characters?
Characters shared beyond the taxon we are trying to define.
What are shared derived characters?
Evolutionary novelties unique to a particular clade.
What are phylogenetic trees built from?
Characters (or sites); can be morphological, behavioral, physiological, or molecular.
What are the two important assumptions about phylogenetic characters?
- They are homologous
- They are evolving independently from each other.
What does a monophyletic group (clade) consist of?
An ancestral species and all of its descendants.
What does a paraphyletic group consist of?
An ancestral species and some of its descendants.
What does a polyphyletic group consist of?
A group of species that does not include their common ancestor.
