Lecture 3: Taxonomy

Question 1

Define taxonomy. Is this a natural or artificial classification system?

Answer 1

A formal classification system used in biology to name, classify, and order species into groups based on similar morphological characteristics. Also called the Linnaean classification system because it was developed by Carolus Linnaeus. This is an artificial classification system because it based on physical (morphological) characteristics.

Question 2

What is the taxonomic hierarchy?

Answer 2

The order for which species are classified into groups and with each sequential level, the groups become more inclusive.

Question 3

List the taxonomic hierarchy from most inclusive to least inclusive

Answer 3

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 4

What is the binomial nomenclature? What is the difference between typing and writing it? give an example.

Answer 4

The two-part scientific name for a species that is written in Latin. The first part is always the genus, which is capitalized, and the second part is always the species name, which is never capitalized. When it is typed, the words are italicized and when it is written, the words are separately underlined. For example, “Homo sapiens,” is the scientific name for humans.

Question 5

What is a taxa (Pl. taxon)? give an example

Answer 5

The unit for any group in the taxonomic hierarchy. for example, the Genus, or the species, or the order is a taxa.

Question 6

Define phylogeny

Answer 6

A hypothesis for the evolutionary history of a species or group of species

Question 7

What does a phylogenetic tree demonstrate?

Answer 7

The evolutionary relationship between species by showing the branches of a common ancestor and how it has developed into the present day species

Question 8

Define systematics. Is this a natural or artificial classification system?

Answer 8

a classification system that classifies species based on their phylogenies or evolutionary relationship to one another. this is a natural classification system because it based on DNA

Question 9

Why is the artificial classification system (the Linnaean system) insufficient in comparison to the natural classification system (Systematics)?

Answer 9

The Linnaean system classifies species based on morphological (physical) features and does not depict actual evolutionary or ancestral relation between species. Whereas, the natural system classifies species based on DNA.

Question 10

Define sister taxa

Answer 10

The taxa that are most closely related because they share a common ancestor

Question 11

Define basal taxa

Answer 11

The taxa that diverges from the common ancestor the earliest

Question 12

What does the root of a phylogenetic tree represent?

Answer 12

The ancestral lineage or the earliest known common ancestor

Question 13

What taxa belong at the tips of the tree branches in a phylogenetic tree?

Answer 13

The LIVING species that are descendants of the common ancestor

Question 14

Define clade. Which classification system uses clades? Explain how it works

Answer 14

A common ancestor and all of its descendants are described as a clade.
Clades are used in the systematic classification system (natural). Clades are nested within larger, more inclusive clades (like how taxa works in Linnaean system)

Question 15

What is the three-domain classification? Identify the key groups of organisms. Where does domain sit in the Linnaean taxa system?

Answer 15

A classification of cellular life forms. It includes all organisms and is the most inclusive of taxa in the Linnaean system.

1. Domain Bacteria
2. Domain Archaea
3. Domain Eukarya

Question 16

Define biological species (the definition we will use for species in this class)

Answer 16

a group of individuals from a population of the same species who are reproductively compatible and can produce viable, fertile offspring and cannot reproduce viable offspring with individuals from a different group

Question 17

Define Domain Bacteria and which organisms are in it?

Answer 17

A domain (large, inclusive group of organisms) that consists of multiple kingdoms of the most diverse bacteria (prokaryotes)

Question 18

Define Domain Archaea and which organisms belong to it? Examples of Archaea?

Answer 18

A domain (large, inclusive group of organisms) that include multiple kingdoms of prokaryotes, called Archaea, that inhabit the most extreme environments of the earth.
Ex. Halophiles and Thermophiles

Question 19

Define Domain Eukarya and which organisms belong to it? Which are the kingdoms within it?

Answer 19

A domain (large, inclusive group of organisms) that consists of 3 main Kingdoms and 1 subgroup. This domain includes all of the Eukaryotic species. Eukaryotes are organisms with cells that contain membrane-bound nuclei and organelles. 
Kingdom Animalia, Kingdom Plantae, Kingdom Fungi, Protists

Question 20

T or F: our modern classification system is based on a natural classification system (ie. systematics)? why/why not?

Answer 20

False. Our modern classification system is based on an artificial classification system (the Linnaean classification system) because even though it doesn’t necessarily reflect evolutionary relationships, basing taxonomy on shared morphological characteristics is actually quite often a depiction of evolutionary relationship

Question 21

why does Linnaean taxonomy often reflect evolutionary relationships?

Answer 21

Because related organisms tend to look more similar to each other

Question 22

In what way is the Linnaean taxonomy inaccurate? how does it happen?

Answer 22

Occasionally there are misclassifications with this system because some traits are lost during evolutionary history or some traits arise independently (derived traits) due to environmental differences or when there are gaps in the fossil record

Question 23

List the evolutionary order of major groups appearances? oldest to newest?

Answer 23

1. oldest prokaryotic fossils appear
2. oldest eukaryotic fossils appear
3. diverse algae and soft-bodied invertebrates appear
4. sudden diversity of animal phyla due to the mass production of O2.
5. colonization of land by plants, fungi, and animals
6. diversification of early vascular plants
7. extensive forests of vascular plants; first seed plants appear; reptiles appear
8. appearance of present-day insects
9. gymnosperm dominant landscapes; origin of mammals
10. angiosperms appear and diversify
11. major radiation of mammals, birds, and pollinating insects
12. angiosperms dominate; present-day mammal species appear
13. origin of primate species
14. earliest human ancestors appear
15. origin of genus Homo
16. Homo sapiens appear