T4 - Systematics and Phylogeny

Question 1

Systematics

Answer 1

The theory and practice of classifying organisms based on phylogeny

Question 2

Phylogeny

Answer 2

the current hypothesis for the evolutionary history of a species or group of related species

Question 3

Phylogenetic trees

Answer 3

Show the hypotheses of the evolutionary relationships between organisms through evolutionary descent and common ancestors

Question 4

What are the two ways we can infer phylogeny?

Answer 4

1. morphological data
2. molecular data

Question 5

morphological data

Answer 5

similarities between anatomical features

Question 6

molecular data

Answer 6

similarities in molecular structures (DNA, RNA, protein)

Question 7

Speciation

Answer 7

the divergence of two species from a common ancestor

Question 8

sister taxa

Answer 8

two descendants from the same node/common ancestor

Question 9

Basal Taxon

Answer 9

species that diverges early in the evolutionary history of a group, closer to common ancestor

Question 10

Clade

Answer 10

a piece of a phylogeny with an ancestor and al its descendants; forms a nested hierarchy

Question 11

Cladograms

Answer 11

phylogenetic trees based oonly on evolutionary relationships

Question 12

Phylograms

Answer 12

phylogenetic trees based on evolutionary patterns AND chronological time of evolutionary change through line lengths

Question 13

Polytomies

Answer 13

a part of a phylogeny that speciates into 3 descendants

Question 14

2 causes of phylogenetic polytomies

Answer 14

1. Lack of knowledge
2. rapid speciatione.g. maybe quick displacement of species

Question 15

Name 1 similarity about groups and 1 general difference between taxonomy and systematics.

Answer 15

Similarity: taxonomic rank = clades

Difference: the criteria used for grouping (similarity/difference vs. phylogeny)

Question 16

Homology/homologous traits

Answer 16

similarity in shared ancestry between two species

Question 17

Analogy/Analgous traits

Answer 17

similarities between species due to convergent evolution

Question 18

Convergent evolution

Answer 18

independent evolution of similar traits in different lineages

Question 19

Which is used in phylogenetic trees? Homologous or analogous traits?

Answer 19

Homologous ONLY

Question 20

Characters

Answer 20

anatomical, physiological, or molecular features of organisms

Question 21

Ingroup vs. Outgroup

Answer 21

Ingroup: group of taxa whose evolutionary relationships you want to compare/determin

Outgroup: usually used as a reference point for making phylogenetic trees (basal taxon), diverged from ingroup at an earlier time

Question 22

Cladistics

Answer 22

A method of inferring phylogeny from homologous characters

Question 23

Monophyletic

Answer 23

a grouping that consists of only the ancestor and its descendants; clade

Question 24

Paraphyletic

Answer 24

A group that consists of an ancestral taxon but not all of its descendants

Question 25

Polyphetic

Answer 25

A group that includes distantly-related taxa but not the common ancestor

Question 26

Three causes of polyphyletic grouping

Answer 26

1. incorrect taxonomic classification
2. group is missing common ancestor
3. more than one common ancestor

Question 27

Shared, derived character

AKA synamorphy

Answer 27

shared by 2+ taxa and most recent common ancestor, but NOT in the ancestor preceeding the clade

Question 28

shared, ancestral character

AKA symplesiomorphy

Answer 28

shared by 2+ taxa AND taxa in an earlier clade

Question 29

Apply Occam’s razor in phylogeny

Answer 29

the tree with the least number of derived character changes is the most probable explanation for evolution

Question 30

T/F: A phylogenetic tree is defined as ‘factual” after 10 years without changes.

Answer 30

FALSE. The phylogenetic tree is always a hypothesis, and can always be proven wrong.