Biology Cycle 9 - Phylogenetic Trees

Question 1

What is taxonomy?

Answer 1

the science of that identifies, names, and classifies new species and their natural relationships

Question 2

What is binomial nomenclature? Who invented it?

Answer 2

naming species with a two-part scientific name
–> first: genus
–> second: species

Carolus Linnaeus

Question 3

What is genus?

Answer 3

Taxonomic category ranking below a family and above a species

Question 4

What is a specific epithet?

Answer 4

the species name in a binomial

Question 5

Which species concept did Linnaeus use to name new species?

Answer 5

morphological species concept – shared anatomical characteristics

Question 6

What is a classification?

Answer 6

an arrangement of organisms into hierarchical groups that reflect their relatedness

Question 7

How is the taxonomic hierarchy arranged?

Answer 7

domain, kingdom, phylum, class, order, family, genus, species, and subspecies

Question 8

What is a taxon?

Answer 8

organisms included within any category of the taxonomic hierarchy

Question 9

How do taxon show genetic relatedness?

Answer 9

species in the same taxon near the bottom of the hierarchy have more similar characteristics that a taxon near the top

Question 10

does the taxonomic hierarchy relate to ancestry?

Answer 10

organisms in the same genus share a fairly recent common ancestor while organisms in the same class have a more distant ancestor

Question 11

What is phylogeny?

Answer 11

the evolutionary history of a group of organisms

Question 12

What are phylogenetic trees?

Answer 12

a branching diagram depicting the evolutionary relationships of groups of organisms

Question 13

What is a ROOT on a phylogenetic tree?

Answer 13

the common ancestor of all species included in the tree

Question 14

What is a NODE on a phylogenetic tree?

Answer 14

represent a (hypothetical) common ancestor that may be unknown

Question 15

What is a anagenesis?

Answer 15

Gradual evolutionary change that transforms one species into another as its characteristics shift over time

Question 16

How is anagenesis shown in an phylogenetic tree?

Answer 16

Straight line

Question 17

WHAT IS CLADOGENESIS?

Answer 17

Ancestral species undergoes speciation producing two descendants that are both distinct form their common ancestor

Question 18

How is cladogenesis represented on a phylogenetic tree?

Answer 18

Branching - CLADE

Question 19

Does cladogenesis or anagenesis create biodiversity?

Answer 19

Cladogenesis

Question 20

What is a polyphyletic taxon?

Answer 20

Group of organisms that belong to different evolutionary lineages and do not share recent common ancestry
Ex. Bats and birds

Question 21

What is a paraphyletic taxon

Answer 21

A group of organisms that includes an ancestral species and some but not all of its descendants
Ex. Dinosauria includes birds and non flying relatives

Question 22

What is a character state?

Answer 22

One or more forms of a character used in a phylogenetic analysis

Question 23

What is the ANCESTRAL CHARACTER STATE?

Answer 23

A trait that was present in the most recent common ancestor
Aka plesiomorphy

Question 24

What is a DERIVED CHARACTER STATE?

Answer 24

evolved after the most recent common ancestor of the group
Aka apomorphy

Question 25

What are shared and derived traits?

Answer 25

synapomorphy -- trait shared by at least two organisms in the group -- this is important for determining evolutionary relationships

Question 26

What are Why are synapomorphies important for phylogenetic trees?

Answer 26

they are markers for monophyletic lineages (common ancestry)

Question 27

What is outgroup comparison?

Answer 27

identify ancestral and derived characters by comparing the group under study to a more distantly related species that are not otherwise included in the analysis

Question 28

How does outgroup comparison determine if a character is ancestral or derived?

Answer 28

if the outgroup has the trait then it is ancestral

Question 29

What is the principle of parsimony?

Answer 29

The simplest tree, with the least evolutionary changes, is the most likely

Question 30

What are the two statistical approaches of phylogenetic tree determination?

Answer 30

Maximum likelihood - compares the alternative tree with specific models of evolutionary change Genetic distance - calculates the overall proportion of nucleotide bases that differ among species

Question 31

Are animals at the top of the tree of life?

Answer 31

no -- all species have evolved and gained complexity for the same amount of time

Question 32

What are the species at the tips or leaves of a tree?

Answer 32

species that exist in the present = extant

Question 33

How can you determine if a trait is homologous or due to convergence?

Answer 33

1. structural or developmental similarity is more informative than superficial similarity 2. use traits that are known to be homologous 3. use molecular data