Ch 20 Pt 1: Phylogenies and the History of Life

phylogeny

the evolutionary history of a species and its relationship to other species

2 types of phylogenetic trees

• rooted

• unrooted

rooted phylogenetic trees

single lineage (at base) represents common ancestor

unrooted phylogenetic tree

shows relationships but not a common ancestor

bacteria

do not contain a nucleus

archaea

do not contain a nucleus, have a different cell wall from bacteria

eukarya

cells do contain a nucleus. includes plants, animals, fungi, and protists

true or false. archaea are more closely related to eukarya than bacteria.

true

true or false. bacteria are more closely related to eukarya than archaea.

false

phylogenetic tree: root

indicates than an ancestral lineage gave rise to all organisms on the tree

phylogenetic tree: branch point/node

indicates where two lineages diverged

phylogenetic tree: basal taxon

a lineage that evolved early and remains unbranched

phylogenetic tree: sister taxa

when two lineages stem from the same branch point

phylogenetic tree: polytomy

a branch w more than two lineages

systematics

study of phylogenetic relationships

taxa that share a more recent ancestor with one another are more ______ related than taxa whose most recent common ancestor is _____

closely, older

clade

a grouping that includes a common ancestors and all the descendants (living and extinct) of that ancestor (monophyletic groups)

cladistic analysis

groupings organisms in a way that reflects their evolutionary relationship

monophyletic group (clade)

consists of ancestral species and all of its descendants

paraphyletic group

consists of an ancestral species and some, but not all, of its descendants

polyphyletic group

includes distantly related species but does not include their most recent common ancestor

true or false. unless specified, the length of the branch does not indicate amount of time passed since the split (node)

true

taxonomy

grouping or classifying species together based on similarities and differences

father of taxonomy

carl linnaeus

who created the binomial nomenclature for species?

Carl Linnaeus

binomial nomenclature

Genus (group) + “specific epithet”

Which is the correct binomial nomenclature for humans?

1. homo Sapiens

2. Homo sapiens

3. Homo Sapiens

4. homo sapiens

2. Homo sapiens

Linnaeus’s hierarchical classification system

1. Doman

2. Kingdom

3. Phylum

4. Class

5. Order

6. Family

7. Genus

8. Species

9. Subspecies

organisms that belong to the same Order should also belong to the same __________.

a) species

b) family

c) genus

d) class

d) class

characteristics of Linnaeus’s hierarchical classification system

• consists of a hierarchy of groupings called taxa

• organisms that shared obvious phenotypical traits were grouped together

• not based on evolutionary characteristics

• organisms are divided into three large categories: bacteria, archaea, and eukarya

• within each domain is a second category called a kingdom

advantages of phylogenetic classificaiton

• tells evolutionary history

• does not “rank” organisms and does not suggest that 2 identically ranked groups are comparable

• Linnaean classification “ranks” groups of organisms artificially into kingdoms, phyla, orders, etc

cladistics

a method of determining phylogeny or method of hypothesizing relationships among organisms

• analysis depends on characters - anatomical, physiological, behavioral, or genetic sequences

homologous structures

• similar due to evolutionary origin (same ancestral source)

• based on genetics and developmental origin

• divergent evolution

divergent evolution

closely related species develop different traits over time, eventually becoming separate species

analogous structures

• similar due to function or ecological pressures

• characters can be very similar in appearance due to evolutionary convergence

evolutionary convergence

when unrelated species evolve similar features or behaviors

shared ancestral characteristic

all of the organisms in the taxon or clade have that trait

shared derived character

this characteristic derived at some point but does not include all of the ancestors in the tree

maximum parsimony

• fewest evolutionary events

• events occurred in the simplest, most obvious way

morphology regarding maximum parsimony

physical characteristics or traits of organisms, such as shape, size, structure, and other anatomical features, that are used to determine evolutionary relationships

• as measured by the origin of shared derived morphological characters

DNA regarding maximum parsimony

has the fewest base changed

bioinformatics

the application of the tools of computation and analysis to the interpretation of biological data