Block 2 - Phylogeny/ taxonomy and Speciation

Question 1

What is phylogeny?

Answer 1

The evolutionary history of a species or a group of related species

Tree of life

Question 2

Binomial nomenclature

Answer 2

Gives the name of the species
Two part names - genus and a specific epithet
Written: Genus 𝘦𝘱𝘪𝘵𝘩𝘦𝘵

Question 3

List the taxomonic groups from broad to narrow

Answer 3

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 4

What is a basal taxon?

Answer 4

Diverges early in the history of a group and originates near the common ancestor of the group

Question 5

What is a monophyletic group?

Answer 5

Also known as a clade - siginifying that it consits of the ancestor species and all of it’s descendands

Question 6

What is a paraphyletic group?

Answer 6

Consists of the ancestral species and some but not all of the descendants

Question 7

What is a polyphyletic group?

Answer 7

Includes distantly related species but does not include their most recent commin ancestor

Question 8

What is the maximum parsimony of a phylogeneyic tree?

Answer 8

Assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely

Question 9

What is the maximum liklihood of a phylogenetic tree?

Answer 9

Based on probability rules about how DNA changes over time and assumes a tree can be found that reflects the most likely sequence of evolutionary events

Question 10

What is the meaning of orthologous?

Answer 10

Found in a single copy in the genome and are homologous between species

Can be traced to a common ancestor

Question 11

What are paralogous genes?

Answer 11

Resulting from gene duplication - thus found in more than one copy in the genome.

Can diverge witin the species that carries them and often evolve new functions

Question 12

What is the role of horizontal gene transfer?

Answer 12

Disparities between gene trees can be explained by HGT. The movement of genes from one genome to another - results in substantial interchanges of genes between organisms in different domains

Question 13

What is reproductive isolation?

Answer 13

The existance of biological factors (barriers) that impede two species from producing viable offspring

Question 14

What is the offspring from two different species called?

Answer 14

A hybrid

Question 15

How do prezygotic barriers act? 3 ways

Answer 15

Blocking fertilisation from occuring by:

Stopping speices from attempting to mate
Preventing the successful completion of mating
Hindering fertilisation if mating is successful

Question 16

How to postzygotic barriers work? 3 ways

Answer 16

Prevent the hyrid zygote from developing into a viable, fertile adult by:

Reduced hybrid viability
Reduced hybrid fertility
Hyrbid breakdown

Question 17

List 5 examples of prezygotic barriers

Answer 17

• Habitiat isolation:
  . Rarely encounter each other as they occupy different habitats
• Temporal isolation:
  . Species breed at different times of the day, different seasons or different years
• Behavioural isolation:
  . Courtship rituals and other behaviours unique to a species are effective barrier to mating
• Mechanical islolation
  . Morphological differences can prevent successful completion of mating
• Gametic isolation
  . Sperm of one species may not be able to fertilise the eggs of another species

Question 18

List 3 examples of postzygotic barriers

Answer 18

• Reduced hybrid viability
  . Genes of the different parent species may interact and impair the hybrid’s development or survival in it’s environment
• Reduced hybrid fertility
  . Hybrids may be sterile
• Hybrid breakdown
  . Some first generation hybrids are fertile but when they mate with each other or with either parent species, offspring of the next generation are feeble or sterile

Question 19

What is allopatric speciation?

Answer 19

Gene flow is interupted or reduced when a population is divided into geographically isolated subpopulations.

Separated popilations may eveolve independenly through mutation, natural selection and genetic drift

Question 20

What is sympatric speciation?

Answer 20

Speciation occurs in populations that live in the same geographic area.

Gene flow can be interupted by polyploidy, sexual selection and habitat differentiation

Question 21

What is polyploidy?

Answer 21

The presence of extra sex hormones due to accidents during cell division. More common in plants than in animals.

Can create a new biological species in sympatry within a single generation.

Many important crops are results of polyploidy (eg oats, cotton, potatoes, tobacco and wheat)