Reticulate Evo

Question 1

7 concepts of reticulate evolution

Answer 1

1 recombination
2 hybridisation - sexual reproduction between species
3 polyploidy - multiplication of chromosomes
4 introversion - back-crossing of a hybrid with one of the parental species, leading to some genes being fixed in the parental line
5 Genome fusion - possible conjugation of cells
6 Endosymbiosis - ancestral origin of mitochondria and plastids
7 HGT - largely by conjugation in prokaryotes

Question 2

Introgression

Answer 2

Used to explain the evolution of modern humans, combining some elements of earlier hominids
Hybridisation between Homo salients and Neanderthals/Denisovans, offspring mate back into human population
Requires reticulate evolution interpretation instead of sequential one

Question 3

What is reticulate evolution?

Answer 3

The production of networks when evolutionary relationships do not fit a tree model

Question 4

Horizontal gene transfer

Answer 4

These networks can become very complex and begin to question the validity of the species concept
Analysis of E. Coli show complex, ongoing process of HGT between strains
Viewed as less prevalent in eukaryotes
Evidence of HGT from fungi in humans - HAS-1 genes

Question 5

Genome fusion

Answer 5

Woese 1990 - proposed 3 domain tree of life
However early meta pan evolution shows there were a lot of genome fusion’ events
Rivera and Lake 2004 - genome fusion between two prokaryotes form eukaryote genome