Lecture 1: Phylogenetic Review & Virology

Dear King Philip Came Over For Good Soup

Domain Kingdom Phylum Class Order Family Genus Species

What is a homologous character trait?

A character inherited from a common ancestor, despite different functions (human arm & bird wing)

What is an analogous character trait?

a trait that is similar between two different lineages of species that are independently acquired (bird wing vs bat wing / similar env pressures)

What is convergent evolution?

When organisms from different lineages independently develop similar adaptations because they experience similar environments/selection pressures

What are sister taxa?

share an immediate CA

What is this part of a phylogenetic tree?

Sister taxa

What is this part of a phylogenetic tree?

Root

What is the root of a phylogenetic tree?

most recent common ancestor of all taxa in the tree

What is this part of the phylogenetic tree?

polytomy

What is a polytomy?

a branch point from which more than two descendant groups emerge

What is this part of the phylogenetic tree?

basal taxon

What is a basal taxon?

a lineage that diverged early in the history of the group

What is this part of a phylogenetic tree?

branch point

What is a branch point?

a point where one lineage splits into two or more descendant groups

What is a monophylectic group?

a clade that contains a single common ancestor and ALL descendants

What is this?

a monophyletic group

What is a paraphyletic group?

a group that contains SOME but not all descendants

What is this?

paraphyletic group

What is a polyphyletic group?

A group of distantly related species that does not include a most recent CA

What is a shared derived character?

a character unique to a clade and used to identify that clade

What is evolution by natural selection?

beneficial traits increase in frequency over generations (change in allele frequencies)

What are three key characteristics of viruses?

nonceullar, invade host cells, and can’t produce on their own

What genetic material can viruses have?

DNA or RNA (single or double stranded)

What are the five general steps of viral replication?

1. bind to host cell

2. genome enters cell

3. genome replication & gene expression

4. assembly

5. exit (leave host cell & infect other cells)

Difference between lytic cycle & lysogenic cycle

lytic kills the host & lysogenic replicates without destroying host

what is a phage?

a virus that infect bacteria (NOT bacteria)

what phages use the lytic cycle?

virulent phages

what phages use BOTH lytic & lysogenic cycles?

temperate phages

What happens during viral attachment?

virus binds to host cell

What happens after viral attachment?

viral genome enters host cell

What happens during viral assembly?

New viral components are assembled into viruses

What happens during viral exit?

new viruses leave the host cell to infect other cells