1. Populations and Communities

2. A group of individuals of the same species, living in a shared space at a specific point in time = Population

3. Factors affecting population size birthsdeaths Population Immigration Emigration

4. How big is this population? 6 11 6

5. Counting populations I - Counting individuals - Counting by sampling: Population size = Average number of individuals per section x Area of section total study area - Counting by recapture %:

6. Counting by recapture % d d d d d d # of marked recaptured animals # of captured animals # of marked animals Population size =

7. Population density Factors influencing population density: – Access to water and food – Presence of predators – Parasites, diseases Pop. Density = # of individuals Space occupied (area / volume)

8. Population distribution = the way in which individuals are dispersed within their habitat clumped random uniform http://www.youtube.com/watch?v=1yKxUNP_XVo&list=PL9CE54703E2B8E92F

9. clumped random uniform

10. Ecological factors = aspect of a habitat that can affect the organisms living there amount of light soil / water pH terrain temperature air humidity birth rate disease amount of food predation competition human activity Related to the action of living organisms Physical or chemical origin Abiotic Biotic

11. Limiting factor A factor that limits the growth of a population – Light – Temperature – Water – Food / nutrients –…–…

12. Limiting factor Is low temperature limiting growth of vampire bat population? Vampire bat colonies Mean minimal temperature for January > 10°C

13. 12 m 200 m Distance between nest boxes Density (pairs / ha) pied flycatcher Is nesting space limiting? Providing more nesting spaces increases population density  Nesting space was limiting

14. Biological cycles in populations Population cycles are composed of alternating rise and fall of population size. Periods are of fixed duration and are repeated continually.

15. Populations Counting methods Density (number/ area) Distribution (clumped/ random / uniform) Ecological factors – limiting factors  Polpulation cycles commuities

16. organism population community Communities: A set of populations of different species sharing the same habitat

17. Biodiversity The variety of species living in a community Species richness: Number of different species in a community Relative species abundance: Number of individuals of one species in relation to total community

18. Same species richness; community 2: species abundance not even  Lower biodiversity Biodiversity is high when: number of species high relative abundance of species similar

19. Interactions between individuals Competition: Living organisms seek access to the same resource in their habitat. Predation One feeds on the other. Mutualism: Interaction between two species beneficial to both. Commensalism: One organism benefits from relationship while other remains unaffected.

20. Competition interspecific intraspecific

21. Predation: predator prey prey may or may not die parasite host Parasite lives either on or inside the host. Host is harmed from the interaction.

22. mutualism Bee gains food Flower gains fertilization Clown fish gains protection Anemone gains prey (attracted by clown fish)

23. Commensalism Bird gains food Human remains unaffected Bird gains protection tree remains unaffected