Chapter 20: Phylogeny

Define phylogeny

evolutionary history of a species or group of related species

How do biologists reconstruct phylogenies?

Systematics

How is the scientific naming system oriented

The first part is the name of the GENUS and the second is the EPITHET.

The evolutionary history of a group of organisms can be represented with _____.

phylogenetic tree

Define phylogenetic trees

branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.

Define basal taxa

a taxon that diverged early on the phylogenetic tree (less closely related)

How do we know if theres uncertainty in the phylogenetic trees?

If there’s polytomy

Define polytomy

2+ lineases stemming from a single branch point; indicates that evolutionary relations are not clear.

Define clades

group of species that include common ancestor + all descendants (also known as a monophyletic group)

Define paraphyletic

taxa with common ancestor and only SOME descendants

polyphyletic

taxa with distantly related organisms but no common ancestor

Taxa’s are only considered a clade if they are_____.

Monophyletic

Define shared ancestral charachter

charachteristic shared by members of a clade that originated in an ancestor that is not apart of the clade.

Shared derived charachter

trait that is UNIQUE to a clade

Define outgroup (basal taxon)

species that has diverged from the phylogenetic tree BEFORE the lineage that contains the species being studies

What does it mean if a charachter is found in both the outgroup AND the ingroup?

Its ancestral

Fossils indicate dinos had feathers. If birds are descended from dino’s, feathers ae what kind of character

shared ancestral characteristic

What can produce an estimate oh phylogeny?

• behavior

• DNA sequences

• protein sequences

• morphological (physical) characteristics

convergenet evolution may occur when _____.

species have similar ecological roles

Example of an analogous structure?

wings of bee and bird

The greatest number of shared derived characteristics that can be found are placed in the same ______.

family

What segments of DNA would have the fastest molecular clock rate?

psuedogene

Define psudeogene

lost sequences needed for expression

THe prescence of _____, indicates a lack of adequate data on a phylogenetic tree

polytomy

Purpose of including an outgroup in a phylogenetic tree is _________.

determining hich charachters are ancestral

Describe the tree of life from analysis of DNA sequence data

3 domains: Bacteria, Eukarya, and Archae + substancial gene transfer during early period(s) of life.

What produces the most reliable phylogenetic tree?

DNA sequences + the fossil record

What is the order of classification?

Domain → kingdom → phylum → class → order → family → genus → species

Define parsimony

a problem solving rule that states the SIMPLEST scientific explanation that fits the evidence is the BEST one.

Define homoplasies

anologous structures that arise INDEPENDENTLY from one another

The work of which individual is directly associated with the principle of parsimony?

Occam

Who is occam?

the dude who proposed parismony (simple is the best)

In the 5 kingdoms of the 60’s, how many kingdom include prokaryotes?

ONE!

Example of horizontal gene transfer?

Endosymbiotic origin of mitochondria in eukaryotes from free floating backteria

Define horizontal gene transfer

movement of genetic material between organisms that are not parent and offspring (happened a lot in the early periods of earths existence)

Whats the most inclusive taxon after family?

Order

Example of a statement that is correct about horizontal gene transfer is

its had a major effect on the evolution of life on earth.

A discipline that is focused on classifying organisms and determining their evolutionary relationships is __________.

systematics

Universal phylogenetic trees built from different genes sometimes give inconsistent results. What assumption, on which phylogenetic trees are based, has probably been violated during the history of life, causing this confusion?

that all things do vertical gene transfer when actually some do horizontal.