xenobiotics

Question 1

Characteristics of human-modified ecosystems

Answer 1

High natural resource extraction
 Short food webs
 Food web simplification
 Habitat homogeneity
 Landscape homogeneity
 Heavy use of pesticides
 Large importation of non-solar energy
 Large importation of nutrients
 Convergent soil characteristics
 Modified hydrological cycles
 Global mobility of people, goods and services

Question 2

What are the major ecological, genetic, environmental and toxin-specific factors that will influence rates of adaptation?

Answer 2

Population size (mutation supply rate)
Generation time
Frequency of exposure
Duration of exposure (persistence)
Concentration of toxin
Genetic variation (standing genetic variation)
Mutation rate
Reproductive system (sexual, asexual, outcrossing, horizontal gene transfer)
Cost of adaptation (fitness cost)
Benefit of adaptation
Genetic architecture of evolved trait (single major gene / polygenic)
Dominance / recessivity
Spatial and temporal heterogeneity of toxin (refugia)
Diversity of mechanisms of adaptation

Question 3

Evolutionary rescue

Answer 3

Evolutionary Rescue (ER) occurs when genetic adaptation allows a population to recover from demographic effects initiated by environmental change that would otherwise cause extirpation.

Question 4

Some specific examples of adaptation to human activity

Answer 4

Heavy metals
Radiation
Oil spills
Xenobiotics (antibiotics and pesticides)

Question 5

Sources of anthropogenic heavy metal pollution

Answer 5

Mining, smelting and refining metals
Burning of fossil fuels
Agricultural inputs (sludge, pesticides)
Manufacturing

Concentrations of ‘available’ heavy metals in the biosphere are much higher than pre-industrial levels

Question 6

Heavy metal tolerance in plants: A model evolutionary system.

Answer 6

Rapid human-driven evolution

Evolution from standing genetic variation

Single gene versus polygenic evolution?

Costs of resistance?

Question 7

Molecular mechanisms of heavy metal tolerance

in plants

Answer 7

. Metal movement restricted by mycorrhizas

2. Binding to cell wall / root exudates
3. Reduced influx
4. Active efflux
5. Chelation in cytosol
6. Repair and protection of plasma membrane

7/8. Transport into vacuole.

Question 8

heavy metal hyperaccumilation by..

Answer 8

increased transport
sequestration
inactivation
increased uptake

Question 9

Bioremediation of heavy metals by plants

Answer 9

Agrostis capillaris var. Parys Mountain

evolved Cu tolerance in situ

produced commercially and used for soil stabilisation and bioremediation at other Cu-contaminated sites
Parys Mountain, Anglesey, Wales

Question 10

Oil spills: Deepwater Horizon, April 2010

Answer 10

Physical / chemical alteration of natural environments
Physical smothering of fauna and flora
Toxic effects
Changes in biological communities

Question 11

bioremediation salt marsh

Answer 11

Rapid bioremediation is occurring in salt marsh habitats, driven by changes in bacterial community composition and relative abundance of catabolic and stress-responsive genes.

Immobilization of oil
Presence of hydrocarbon-degrading species in rhizosphere
Plant uptake
Increase aeration in root zone

Question 12

Marine microorganisms make a meal of oil

Answer 12

Aerobic bacteria that degrade hydrocarbons are increasingly being thought of as key players in the removal of hydrocarbons from oil-polluted marine environments. The organisms shown in blue can degrade saturated hydrocarbons, whereas those shown in red can degrade polycyclic aromatic hydrocarbons. The organisms shown in black do not degrade hydrocarbons.