Phylogeny, Taxonomy, and Systematics

Question 1

Taxonomy

people?
pre-dates what?

Answer 1

The science of naming, describing, and classifying organisms

-well developed in native peoples who live on the land

pre-dates the science of evolutionary biology

Aristotle was the first greek biologist and historical figure to classify organisms

Question 2

Taxonomy’s importance

-new species? many species?
-relevent to what?

Answer 2

New species being discovered all the time
-relevant to studies of biodiversity and conservation
-many species become extinct before they are described

Question 3

Why is biodiversity being lost?
what does taxonomy provide?

Answer 3

Human activities cost an unprecedented amount of biodiversity

Taxonomy provides a basic understanding about the components of biodiversity

Question 4

Carl Linnaeus did what?
What was his world view?

Answer 4

Published Species plantarum and System Naturae, describing and classifying plants and animals
-pre-evolutionary
believed he was cataloguing the plan of the Creator,
believed in the fixity of species

Question 5

Linnaeus’ popularized what?

Answer 5

Popularized binomial nomenclature - where each species has a unique scientific name formed by the combination of the genus name and a specific epithet (e.g. Homo sapiens)

Question 6

Linnaeus created what system?

Answer 6

Taxonomic classification system
-classification of all life within a hierarchy
-based on morphological characteristics

Life -> Domain -> Kingdom -> Phylum -> Class -> Order -> Family -> Genus ->Species

Question 7

Taxonomic conventions
What is capitalized?

Answer 7

Phylum, subphylum, and class names are all capitalized
Genus name is capitalized, species name is lowercase (both are italicized or underlined)

Question 8

Charles Darwin
year?
What did he do?

Answer 8

Proposed species changed over time (evolution)
In 1859
Hypothesized a mechanism for evolutionary change was natural selection

Believed all life was related on the basis of genealogical descent from a common ancestor

Question 9

Taxonomy

Answer 9

The science of naming, describing, and classifying organisms

Question 10

Systematics

Answer 10

The study of evolutionary relationships between organisms

Question 11

Phylogeny

Answer 11

The evolutionary history of a group

Question 12

Phylogenetics =

Answer 12

Systematics

Question 13

What is phylogeny?

Answer 13

A phylogeny is a hypothesis of evolutionary relationships among species

Question 14

Phylogenetic tree

Answer 14

Is called a cladogram, and is a graphical representation of a phylogenetic hypotheses

Question 15

Understanding phylogenetic tree

Answer 15

Root of the tree represents ancestral lineage

Tips represent descendants

As you move from the root to the tips, you move forward in time

Question 16

speciation event

Answer 16

It is represented as branching on a phylogeny and is called a speciation event

Question 17

Phylogenetics

Answer 17

Allows us to study how certain traits evolve over time

Question 18

Applications of phylogenetics (look at slide 22 and save photo for conservation point)

Answer 18

Tests hypotheses about long-extinct organisms

Uncovering the origins of Covid

Making conservation decisions by saving more, rather than less

Question 19

Phylogenies made because?

Answer 19

In the absence of a perfect fossil record, we can never be certain of evolutionary history

Systematists have developed methods for inferring evolutionary relationships

These methods result in hypotheses of ancestor-descendent relationships

Question 20

Character

Answer 20

Any feature that is used to examine variation with and among groups (taxa)

Question 21

Types of features

Answer 21

Anatomical, cellular, biochemical, developmental characters (gene expression)

Question 22

Protostomes vs Deuterostomes

Answer 22

Developmental characters can be used for generating phylogenetic hypotheses

Question 23

Homology vs Homoplasy

Answer 23

Homology : Similarity due to common ancestry. Reveals a phylogenetic relationship

Homoplasy : Similarity that is not due to common ancestry (convergence or reversal) Does not reveal a phylogenetic relationship

Question 24

Convergence

Answer 24

Adaptations that formed independently due to similar environmental conditions by distantly related organisms

This is not due to common ancestry, rather adaptation and evolution AND HOMOPLASY

Question 25

Myrmecophagy

Answer 25

Animals that specialize in eating ants

Question 26

Reversal

Answer 26

Loss of a derived feature with the reestablishment of an ancestral feature

Question 27

Because homoplasies do not…. only ….

Answer 27

Reflect evolutionary history, only homologies should be used for reconstructing phylogenies

Question 28

Synapomorphy

Answer 28

Inherited from most recent common ancestor
Shared derived homology

Question 29

Symplesiomorphy

Answer 29

Shared ancestral homology
Inherited from more distant common ancestor

Question 30

Symplesiomorphies aren’t useful for…

Answer 30

Inferring relationships between members of a group, rather characters that vary need to be examined across lineages in the clade

Question 31

Cladists only use…

Answer 31

Synapomorphies to infer phylogeny

Question 32

Outgroup

Answer 32

A group that is phylogenetically close to, but is not contained in the study group of interest

Question 33

Order -> Species

Answer 33

Order ->
Suborder ->
Family ->
Genus ->
Species

Question 34

Monophyletic, para, poly

Answer 34

Mono is the whole group
Para is some of the group
Poly is some of two groups (convergent evolution describes polyphyletic relationships)

Question 35

Other fish and lungfish are…

Answer 35

Paraphyletic, with respect to amphibians

Question 36

Inclusion of homo makes…

Answer 36

Pongidae and Homo monophyletic

Question 37

Why do phylogenies and taxonomies change over time?

Answer 37

New data becomes available
-new tech, basic info becomes available, data on new species
Different types of data yield different phylogenies
-molecular vs morphological
Somewhat different techniques may be used to analyze data

Question 38

Mono, para, poly phyletic

Answer 38

Mono - Includes an ancestor and all its descendants
Para - Includes an ancestor and some but not all of its descendants
Poly - Includes two distant relatives but not their common ancestor

Question 39

Phylogenies, at the end of the day, are…

Answer 39

HYPOTHESES, THAT ARE SUBJECT TO CHANGE WHEN NEW DATA IS AVAILABLE

Question 40

Define/Relate
taxonomy, systematics
monophyletic, synapomorphy
paraphyletic, symplesiomorphy
polyphyletic, homoplasy
convergence, reversal

Answer 40

Taxonomy - the science of naming, describing, and classifying organisms
Systematics - The study of evolutionary relationships
Taxonomy gives us methods to describe evolutionary relationships with linnaean hierarchies. Systematics seeks to describe evolutionary relationships that can be described used taxonomy. I.E. Class -> order -> family -> genus -> species can describe evolutionary relationships.

Monophyletic - a group that has all the descendants of a common ancestor
Synapomorphy - A trait that is inherited from a most recent common ancestor of a group cladistic group
Synapomorphies are the most recent state of a character that all monophyletic groups evolved from.

Paraphyletic - Not all descendants of a recent common ancestor are grouped together - leaving some out
Symplesiomorphy - A shared ancestral homology of a group that is not inherited from a most recent common ancestor, rather a more ancient ancestor.
Paraphyletic groupings can have ancestrally derived characters in the form of symplesiomorphies and this can be helpful in inferring evolutionary relationships between members of a group.

Polyphyletic- When a relationship is made between two distantly related groupsoui but not a common ancestor
Homoplasy - Similarity that is not due to a phylogenetic relationship. For example, convergent traits or reversal to an ancestral character state
Polyphyletic groupings can have identical derived character states that groups did not evolve from a recent common ancestor, rather it would evolve from similar environmental pressures. Homoplasies do not reveal a phylogenetic relationship nor do polyphyletic groups because they do not focus on similarities due to common ancestry and focus solely on the character state.

Convergence - When the same character evolves independently in groups that have distantly related ancestors
Reversal - When a derived character state reverts back to the ancestral character state
Both of these are homoplasies and cannot be used to infer phylogenetic relationships.

Question 41

We are currently in the midst of a taxonomic revolution, whereby many previous-recognized taxonomic groupings (e.g., reptiles, fishes) have either been discarded or reclassified. In your own words, describe the main reasons for this taxonomic revolution.

Answer 41

New means of acquiring data on how evolutionary relationships is changing the game. It is revealing that there may be more members of a group than initially thought. Taxonomic groupings sought to group similar things together for the sake of clarity; however, some of these groupings were based solely in character state and not actual derivation. Genetic studies are showing that some other things may also be included in a taxonomic group. Monophyletic groups paint a clearer picture for evolutionary relationships as well, so previously-recognized taxonomic groupings have to be thought of as subject to change based on new scientific findings and not hard truths.

Question 42

Review multiple choice