Lecture 22

Question 1

Carolus Linnaeus

Answer 1

The founder of taxonomy
* Binomial nomenclature
* Hierarchical system
of classification
kingdoms
phyla
classes
orders
families
genera
species

Question 1

What is the Purpose
of a Biological Classification?

Answer 1

Name is a key to shared information on
an organism
* Therefore has predictive power
* Enables interpretation of origins and
evolutionary history

Question 2

Taxon

Answer 2

single named taxonomic unit at any level
– Plural = taxa
kingdoms
phyla
classes
orders
families
genera
species

Question 3

Taxonomy

Answer 3

The theory and practice of classification &
naming

Question 4

Systematics

Answer 4

The study of biodiversity and the evolutionary
relationships among organisms

Question 5

Terminal nodes

Answer 5

Taxa

Question 6

Terminal branches

Answer 6

Accumulated
evolutionary change

Question 7

Internal nodes:

Answer 7

Common ancestors
* Speciation

Question 8

Internal branches

Answer 8

Accumulated
evolutionary change

Question 9

Why Conduct Phylogenetic Analysis?

Answer 9

• Understand history of life
• Understand large-scale patterns of evolution
• Understand how many times traits have evolved,
  how fast, under what conditions
• Practical:
• Where/when did parasites spread?
• Which flu strain was the most successful
  last year?
• What are the driver mutations as SARS-
  COV-2 evolves?

Question 10

Understanding Phylogenetic Trees

Answer 10

Different relationships among taxa on trees
represent different hypotheses or conclusions
about evolutionary history

Question 11

Monophyletic group

Answer 11

includes the complete set
of species derived from a common ancestor
- single ancestor gave rise to all
species in that taxon and no species in
any other taxon

Question 12

Paraphyletic group

Answer 12

contains some, but not all
species derived from a common ancestor
- A taxon whose members are derived
from two or more ancestral forms not
common to all members

Question 13

Phylogenies as a Forensic Record

Answer 13

Species that share a more recent common ancestor
tend to be more similar
* Descent with modification

Question 14

A critical step in the reconstruction
of phylogenetic history is
the identification and distinction of
ancestral and derived traits.

Answer 14

Ancestral trait = A trait shared with
a common ancestor
* Derived trait = A trait that differs from
the ancestral trait in a lineage

Question 15

Homology & Homoplasy

Answer 15

Homology
* Similarity of traits due to shared ancestry
Homoplasy
* Similarity of traits as a result of convergent
evolution

Question 16

Convergent Evolution

Answer 16

• The independent evolution of structures
  that resemble one another and
  perform similar functional roles due to the
  shared ecology of unrelated organisms

Question 17

Convergent Evolution in Cichlid Fishes
of the African Great lakes

Answer 17

Independent
evolutionary radiations
in two lakes
* Similarity in form
indicates convergence
in feeding strategies

Question 18

Why Is Molecular Biology Relevant
to Evolution & Phylogeny?

Answer 18

All life is related through branching descent
* Common genetic code is evidence that all
life is related
* Evolutionary relationships among species
are reflected in their DNA and proteins
– Learning about protein function in one species
can tell us about its function in others
– Mice, rats, flies, worms  Humans

Question 19

Inferring Species Relationships
from DNA Sequences

Answer 19

Genes or parts of a gene can be sequenced
for different species
* Species can be assessed for changes in
the sequence of nucleotides
* Changes can be used to infer relationships
in a branching diagram (phylogeny)

Question 20

Using Phylogenies to Understand
the Origin and Evolution of Traits

Answer 20

Origin of a novel trait resulting in
adaptive radiation
* Carriers of the trait can exploit new
resources or sets of habitats
* Usually associated with rapid evolutionary
diversification (e.g. adaptive radiations)

Question 21

Origin of Traits Associated with
Increased Diversification Rate

Answer 21

Diversification = Speciation – Extinction
* Key innovation could increase speciation or
decrease extinction to influence net diversification

Question 22

Why Do Some Groups
Have More Species Than Others?

Answer 22

Use of replicate “sister group” comparisons
- With one phylogenetic comparison, it is difficult to say
a key trait is involved
* Replicate comparisons of multiple groups adds more
evidence

Question 23

Herbivory Associates with Higher Diversification Rate

Answer 23

Coevolution between insects and plants
likely drives higher rates of speciation in herbivores

Question 24

Other Features Associated with
Greater Diversification

Answer 24

• Species with sexual reproduction
• Outcrossing species
• Animal pollination in plants
• Increased dispersal