Chapter 26 - Phylogeny

Phylogeny

the evolutionary history of a species or group of related species

Taxonomy

Classification and naking of organisms

What are two key features of taxonomy?

two-part names for species… and hierarchical classification

Systematics

Taxonomy and evolutionary relationships

What did Linnaeus publish in the 18th century?

Systems of taxonomy

Taxon, tax

A taxonomic unit at any level of hierarchy

How do you taxonomic groups from most inclusive to least inclusive?

Domain kingdom, phylum/division, class, order, family, genus, species.

Sister taxa

groups that share an immediate common ancestor that is not shared by any other group

Monophyletic

A group and all it’s descendants that’s descended from a common ancestor

Outgrop

A species or group of species that is closely related to the ingroup

Ingroup

the various species being studied

Monophyletic Group

Every animal related within that group has a common ancestor

Paraphyletic Group

A group of organisms that have a common ancestor that contains some of its descendants

Polyphyletic Group

A group that includes organisms that lack a common ancestor

How do you know if something is paraphyletic or polyphyletic?

More characters are recognized. Molecular biology will suggest that they are if the original phylogeny was based on morphology alone.

Maximum parsimony

the tree that requires the fewest evolutionary events (changes from 0 to 1 and changes from 1 to 0)

Reversal

When a character changes from the older state to the derived state in another place, reversing from the derived state back to ancestral state.

In DNA sequences, shared ancestry can result from two different processes,

speciation and gene duplication.

Orthologous

A pair of genes that has evolved from the gene in the last common ancestor via speciation.

Paralogous genes

Results from gene duplication and are found in more than one copy in the genome and often evolve new functions

Orthologous genes are…

widespread and extend across many widely varied species.

Horizontal gene transfer

The movement of genes from one genome to another without reproduction, due to bacteria sharing gene, viral infection or endosymbiosis. Between unrelated organisms.

An organism’s evolutionary history is documented in its

genome

What is the most efficient wayy at exploring recent evolutionary events

Mitochondrial DNA

Homologous

Having the same two structures in genes/chromosomes and/or sharing a common origin

Analogous

Body parts within different species that have similar functions but are ultimately different in origins and anatomy

Sister Group (Phylogeny)

Groups that are adjacent to each other at a node in a phylogenetic tree

Point Mutation

When a single nucleotide base within an RNA/DNA sequence and is changed/inserted/deleted

Indel

The insertion or deletion of bases within the genome of an organism

Reversal

The reappearance of an ancestral trait

Sequence alignment

Process of arranging DNA/RNA or protein sequences to find regions/areas of similarity

Molecular Clock

A tool used by scientists to measure genetic mutations over time to calculate the timing of evolutionary events.

It’s main assumption is that genetic mutations accumulate over time at a constant rate