Evolution of parasatism

Question 1

Different stages of phoretic and necromenic associations

Answer 1

Dauer, Phoresy, Necromeny

Question 2

Dauer stage

Answer 2

Specialised, arrested, non-feeding stage - specialised for survival and dispersal
Not parasitic, its necromenic

Question 3

Phoresy

Answer 3

Dauer uses insects for transportation, not species specific

Question 4

Necromeny

Answer 4

Dauer associates with insect host in species specific manner - wait for death then feeds on microbes growing on carcass

Question 5

Brugia malayi

Answer 5

filiarial nematode (lymphatic filiariasis)
- huge proportion of genes on defence
loss of genes encoding for purine, heme and riboflavin
- instead sources from host

Question 6

How do plant parasites puncture cell wall?

Answer 6

They have a stylet. means they can live on plant cells
example meloidogyne incognita and M. halpa

Question 7

Evidence for evolution of parasitism

Answer 7

• comparative analyses of closely related free living and parasitic organisms
• molecular methods comparing DNA sequences
• Horizontal gene transfer

Question 8

What is a pre-adaptation

Answer 8

Adaptations to current environments which might in the future be co-opted to a new function helping the organism in a new niche

Question 9

Pristionchus pacificus

Answer 9

evidence for pre-adaptations
necromenic associations with beetles

Question 10

Why is meloidogyne incognita significant

Answer 10

Presence of cell wall degrading carbohydrate-active enzymes in the genome is an example of horizontal gene transfer

Question 10

Why are horizontal gene transfers significant

Answer 10

key adaptation towards plant parasitism achieved by HGT of cell wall degrading enzymes