Lists for biology, ecology, zoology and botany, 1, 2, 3

Allelochemicals, possible roles in the life of the plant

1. storage of unwanted products.
2. plant structure - cell walls.
3. plant colour and smell.
4. defence against physical factors e.g. cold, salinity, UV light.
5. defence against herbivores.

Essential features of the theory of island biogeography

• number of species increases with increase in island area.
• for an island of a given size number of species decreases with distance from source area.
• continual turnover of species where colonizations are balanced by extinctions.

Advantages of dispersal in plants

1. Reduces chance of offspring/sibling/parent competition.
2. Reduces inbreeding. 3) Increases chance of finding "safe" site.

Types of competition

• Intraspecific competition i.e. competition between individuals of same species.
• Exploitation competition makes resources e.g. food unavailable to others.
• Interference competition occupying space, defending territory preventing others reaching resource.
• Interspecific competition i.e. competition between different species.

Characteristics of pioneer plant species

1. Abundant in soil seed bank.
2. Small seeds.
3. Shade intolerant. Germination only in open sites. Dormancy broken or germination enhanced by high light intensity, high R/FR ratio light, fluctuating or high temp. and/or moisture, high NO₃
4. Rapid growth.
5. Early reproduction.
6. Large investment of resources in reproduction (r-selected).
7. Reproduction continuous or frequent.
8. Mechanisms for distant seed dispersal (birds, insects, wind).
9. Short lived.
10. Genetically diverse.
11. Phenotypically plastic.
12. Low density wood, in trees.
13. Leaves not robust and short lived.

Differences between the flora and fauna of continental and oceanic islands

• Continental islands usually have more species for their size
• Continental islands usually have a subset of mainland species; oceanic islands have a subset of those that are good at dispersal
• Oceanic islands contain a greater number of endemic species.
  Oceanic islands rarely have freshwater fish.
• Oceanic island species often lose their powers of dispersal.
• Oceanic island species may differ remarkable in size from mainland species.