Chapter 26: Phylogeny and the Tree of Life

Question 1

What is taxonomy?

Answer 1

the discipline in which organisms are named and classified

Question 2

What is a binomial?

Answer 2

2-part format of scientific names

Question 3

What is a taxon (taxa = plural)

Answer 3

a taxonomic unit at any level

Question 4

What are the hierarchical classifications from more specific to least specific

Answer 4

species 
genus 
family 
order
class 
phylum 
kingdom 
domain

Question 5

What is a phylogenetic tree

Answer 5

a branching diagram used to represent the evolutionary history of a group of organisms

Question 6

what is a branch point?

Answer 6

a point on a phylogenetic tree that represent a common ancestor of the two evolutionary lineages diverging from it

Question 7

What are sister taxa?

Answer 7

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

Question 8

What is polytomy?

Answer 8

a branch from which more than 2 descendant taxa emerge (often shows unclear evolutionary history)

Question 9

What is the basal taxon?

Answer 9

the taxa that diverges from all other members of its group early in the the history of the group

Question 10

What is the “rooted” branch point?

Answer 10

the most recent common ancestor of all taxa in the phylogenetic tree

Question 11

What is phylogeny?

Answer 11

the evolutionary history of species or groups of species

Question 12

what is homology? example?

Answer 12

genotype and phenotypic similarities due to shared ancestry

ex. forelimbs of whales, horses, bats, and humans

Question 13

what is analogy/homoplasy? example?

Answer 13

phenotypic similarities but not shared ancestry

ex. sugar glider

Question 14

what is convergent evolution? example?

Answer 14

similar adaptation evolving in organisms from different evolutionary lineages due to similar environmental pressures

ex. Australian mole and North American mole
marsupial vs. not (but they look the same!)

Question 15

What are the 4 steps in creating a character table?

Answer 15

1. label one side with taxa and the other with characteristics
2. make sure that the characteristics have yes or no answers (mark 1 for yes, and 0 for no)
3. assign an OUTGROUP
4. Determine the symplesiomorphies and the synapomorphies

Question 16

What is an OUTGROUP?

Answer 16

a taxa that is closely related to the group of organisms that one is studying but not part of the study group

Question 17

What is a synapomorphy?

Answer 17

shared, derived characteristics that represent departure from a common ancestor

Question 18

What is a symplesiomorphy?

Answer 18

shared ancestral characteristics that evolved PRIOR TO THE MOST RECENT COMMON ANCESTOR

Question 19

What is the PRINCIPLE OF MAX. PARISMONY?

Answer 19

a method for deciding evolutionary “closeness” in which the hypothesis with the least possible assumptions is most probable

Question 20

What is the PRINCIPLE OF MAX LIKLIHOOD?

Answer 20

a method for deciding evolutionary “closeness” in which given certain probability rules about how DNA sequences change over time, the hypothesis that reflects the most likely sequences (smaller percent differences between branches) should be supported

Question 21

What is a MONOPHYLETIC group?

Answer 21

A group that includes the ancestral species and ALL of its descendants

Question 22

What is a PARAPHYLETIC group?

Answer 22

a group that consists of the ancestral species and some but not all of the descendants

Question 23

What is a POLYPHYLETIC group?

Answer 23

a group that does not include the common ancestor but does include all of the descendants

Question 24

What are the assumptions we can make about dinosaurs due to the fact that we know they were related directly to crocodiles and birds?

Answer 24

that they sang, made nests, had four chambered hearts, and exhibited brooding behaviors

Question 25

what is the study Systematics?

Answer 25

The analytical approach to understanding the diversity and relatedness of both extant and extinct organism