lecture 1- Phylogenetics and plant classification; endosymbiosis

phylogeny

The evolutionary history of relationships among organisms.

lineage

A series of ancestor and descendant populations represented as a line over time.

What does a node (split) in a phylogenetic tree represent?

A divergence event where one lineage splits into two (e.g., speciation, gene duplication)

root of phylogenetic tree

The common ancestor of all organisms in the tree

taxon

Any named group of organisms (e.g., humans, primates, mammals)

clade

A group consisting of a common ancestor and all its descendants.

What are sister species and sister clades?

Closest relatives in a phylogenetic tree (species or clades).

Why are phylogenetic trees widely used in biology?

They form the basis of comparative biology and help make predictions about traits

homologous traits

Traits inherited from a common ancestor (e.g., vertebral column in vertebrates).

What is the difference between ancestral and derived traits?

Ancestral = original trait; Derived = new version of the trait that evolved later.

synapomorphy

A shared, derived trait that provides evidence of common ancestry.

convergent evolution

Independent evolution of similar traits in unrelated lineages (e.g., bat and bird wings).

analogous traits

Functionally similar traits that evolved independently, not from a common ancestor.

evolutionary reversal

A derived trait reverts back to an ancestral state (e.g., whale fins resembling fish fins)

homoplastic traits (homoplasies)

Similar traits arising from convergent evolution or evolutionary reversals.