Chapter 26

Question 1

Two main approaches to determine evolutionary relationships

Answer 1

morphological characteristics: Size, shape and presence/absence of different anatomical features
Molecular characteristics: Relies on the comparison of specific DNA or protein sequences

Question 2

Phylogenetic tree

Answer 2

are hypotheses of the evolutionary history between different organisms.

Question 3

systematics

Answer 3

discipline focused on classifying organ- isms and determining their evolutionary relationships

Question 4

Taxonomy

Answer 4

Organisms are named and classified

Question 5

Taxon

Answer 5

The named taxonomic unit at any level of the hierarchy

Question 6

Branch point

Answer 6

Represents common ancestor of the two evolutionary lineages diverging from it

Question 7

Root

Answer 7

Branch point represents the most recent common ancestor of all taxa in the tree

Question 8

Basal taxon

Answer 8

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

Question 9

homologies

Answer 9

phenotypic and genetic similarities due to shared ancestry
Ex: the similarity in the number and arrangement of bones in the forelimbs of mammals is due to their descent from a common ancestor with the same bone structure

Question 10

Convergent evolution

Answer 10

Convergent evolution occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages

Question 11

Molecular homoplasy

Answer 11

in organisms that do not appear to be closely related, the bases that their otherwise very different sequences happen to share may simply be coincidental matches

Question 12

Molecular systematics

Answer 12

the discipline that uses data from DNA and other molecules to determine evolutionary relationships.

Question 13

cladistics

Answer 13

common ancestry is the primary criterion used to classify organisms

Question 14

clades

Answer 14

biologists attempt to place species into groups called clades, each of which includes an ancestral species and all of its descendants. Clades, like taxonomic categories of the Linnaean system

Question 15

monophyletic

Answer 15

signifying that it consists of an ancestral species and all of its descendants

Question 16

paraphyletic

Answer 16

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

Question 17

polyphyletic

Answer 17

Which includes distantly related species but not their most recent common ancestor

Question 18

outgroup

Answer 18

species or group of species from an evolutionary lineage that is known to have diverged before the lineage

Question 19

maximum parsimony

Answer 19

investigate the simplest explanation that is consistent with the facts

Question 20

maximum likelihood

Answer 20

approach identifies the tree most likely to have produced a given set of DNA data, based on certain probability rules about how DNA sequences change over time.

Question 21

orthologous genes

Answer 21

the homology is the result of a speciation event and hence occurs between genes found in different species

Question 22

paralogous genes

Answer 22

multiple copies of these genes have diverged from one another within a species

Question 23

molecular clock

Answer 23

Approach for measuring the absolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates

Question 24

polytomy

Answer 24

represents a part of the tree where the relationship among the species is uncertain

Question 25

horizontal gene transfer

Answer 25

process in which genes are transferred from one genome to another through mechanisms such as exchange of transposable elements and plasmids