Explain why 2 or more species can coexist in the same habitat, but NOT in the same niche

Transcription

1 Starter: Answer the following revision questions: 1. Explain the idea of commensalism and give an example 2. What is the difference between inter specific competition and intra specific competition? 3. Explain the difference between BIOTIC and ABIOTIC factors. List 2 examples of each Jun 25 1:32 p.m. Past paper Question 2010 Explain why 2 or more species can coexist in the same habitat, but NOT in the same niche Mar 1 10:51 a.m. 1

2 Explain the relationship between the scale insect and the beech tree: Relationship: Explanation: Explain the relationship between the wasp and the scale insect Relationship: Explanation: Mar 1 10:58 a.m. Gause's Principle of Competitive Exclusion No two species can occupy exactly the same niche. One species will be forced to emigrate or the population will die out. MEMORISE THIS!!!!!!!!!! Feb 28 1:52 p.m. 2

3 BIOLOGICAL COMMUNITIES All plant and animal populations living and interacting in a given area constitute a biological community. The boundaries of a biological community can vary enormously. A piece of rotting log and the organisms living on it can be seen as a community. Equally all the plants, animals and organisms living in and around a large river can be described as a river community. BIOLOGICAL COMMUNITIES 3

4 Biological species in a community are distributed in different ways depending on the community. There are 3 main types of distribution: Stratification Zonation Succession Feb 13 1:56 p.m. Stratification Vertical layers of plant species distribution seen in forests An example is the vertical layering of vegetation that you can see in a forest community. As sunlight passes down through the forest canopy to the forest floor, solar energy is considerably reduced. This results in stratification because different species have different light requirements. 4

5 Stratification Stratification Epiphytes 5

6 Zonation Horizontal distribution of species as a result of an environmental gradient The most common example of this is the rock shore. When the tide is out you can clearly see that different species are found starting at the high tide and walking to the low tide Zonation can also be seen on a mountain. Zonation 6

7 Zonation Jun 25 12:51 p.m. 7

8 This is one way to present this data. The other way is with a kite diagram. Activity: Questions 2, page Jun 25 1:41 p.m. Starter: c Describe stratification. d Discuss how the canopy trees affect the abiotic factors and the other species present in the forest. Jun 25 1:53 p.m. 8

9 Description of stratification The vertical layering (of vegetation in a forest). Achieved Describes how canopy trees affect any ONE of: ACHIEVED light (intensity) humidity temperature wind. The direction of change must be stated (increase or decrease) Light: high light intensity at the top of the forest, decreases as move to lower levels. Humidity: low humidity at the top of the forest, increases as move to lower levels. Temperature: greater range at higher layers /smaller range at lower layers. Wind: air movement is high at the top of the forest, decreases as move to lower levels. Jun 25 1:55 p.m. Merit Gives reason for HOW the canopy trees affect ONE abiotic factor Candidate exemplars The canopy trees are so big that they block some light from the species below. Because the canopy trees cover the trees and plants below them, they protect these plants from strong winds which could damage them. The cover provided by the canopy trees restricts the air movement below and this increases the humidity below the canopy. Canopy trees filter out the light so that the plants below live in a darker environment. Shelter is given to plants below the canopy by the big trees so they don t get exposed to heavy rain and strong winds. Jun 25 1:56 p.m. 9

10 Discussion links the type of vegetation to the changing conditions caused by ONE abiotic factor EXCELLENCE Links include reference to a narrow tolerance range for species below the canopy and/or examples of adaptations. Species lower in forest adapted to lower light intensity (leaves larger / greener), unable to survive in higher light intensity Humidity higher at lower levels and plants tolerate only small changes in humidity levels. Temperature range less extreme in lower layers, plants have a narrower tolerance. Air movement is reduced at lower levels so plants do not have seeds dispersed by wind/high humidity is maintained/plants more fragile. Jun 25 1:57 p.m. Explain in detail the difference between zonation and stratification Mar 3 12:39 p.m. 10

11 Succession Change in species distribution with time. When a community has reached a point where further change ceases or is very slow, we say that it is a climax community. The native plants on the mountains in the interior of a large island such as Viti Levu, Fiji, would represent a climax community. The community has been untouched by human activities. Succession 11

12 Succession Activity: Page 25 # 7 Jun 25 12:51 p.m. 12