Ch.20 Phylogeny (evolutionary mechanisms)

Phylogeny

The evolutionary history of a species or a group of species

Systematics

Analytical approach to understanding diversity and relationships of organisms of extant and extinct organisms

Taxonomy

Naming and categorizing based on similarity

Classification

By Linaeus

A binomial naming system where the

first word = genus

Second word = specific epithet

Hierarchal classification

Linnaeous introduced grouping species in increasingly broad categories

True or false; phylogenetic trees usually match up with linnaeus naming system

True

Sister taxa

Two taxa next to eo which share a common ancestor

Rooted tree

Tree including a branch which represents the last common ancestor of all taxa

Polytomy

Branch which more than two groups emerge from

What information does the phylogenetic tree lack

Dates or times which species evolved and how much genetic change occured

Cladogram

Hypothesis depicting patterns of shared characteristics

Paraphyletic grouping

Including too many taxa in a category which dont belong

Shared ancestral characteristic

Originated in ancestor taxon

Shared derived character

Unique to particular clade

Outgroup comparison

Well selected outgroup where taxon is closely related (used to know if a trait is derived or ancestral)

Similar Morphological and molecular data

Organisms that share morphologies share similar DNA sequences

Using computer programs and mathematic tools to analyze DNA we can

Evaluate molecular homologies

Maximum parsimony

Simplest explanation or path of evolution to another species

Molecular clocks

Use constant chemical rules of evolution in some genes to estimate the absolute time of evolutionary change

Neutral theory

Evolutionary change in genes and proteins have no effect on fitness and is not influenced by selection

Difficulty with molecular clocks

They are not as smooth as neutral theory predicts as some DNA changes are favoured over others

Horizontal gene transfer

The movement of genes from one genome to another