The Environment Habitat and Niche

Transcription

1 The Environment Habitat and Niche Ecology By KAPMAN LIFE SCIENCE ACADEMY Call us at

2 Ecology Scientific study of the relationships between organisms and their environment. Environment comprises of physical and chemical components as well as the biological or living components of an organism s surroundings, that is, Biotic and Abiotic Factors Biotic Factors: Living factors in an organism s environment such as plants, animals, microbes. Abiotic factors: The non-living factors such as air, water, precipitation. 2

3 Abiotic Factors 3

4 Atmosphere 1. Troposphere 2. Stratosphere 3. Mesosphere 4. Thermosphere/Ion osphere 5. Exosphere 4

5 Light 5

6 Water 6

7 Temperature 7

8 Rocks and Soil 8

9 Ecological Levels of Organization Organism: An individual Population: Individual organisms of a single species that share the same geographic location at the same time Community: A group of interacting populations that occupy the same area at the same time 9

10 Ecosystem: A biological community and all of the abiotic factors that affect it Biome: A large group of ecosystems that share the same climate and have similar types of communities Biosphere: All biomes together make the Biosphere ; The Earth 10

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12 Climate Long term pattern of weather in a locality, region, or even over the entire globe. Weather: is the short term properties (temperature, pressure, moisture) of atmospheric conditions for a specific place and time. Climatic zone are Tropical, Subtropical, Temperate and Arctic and Antarctic Microclimate: represents the climatic conditions that prevail at a local scale, or in areas of limited size, such as the immediate surroundings of plants and animals. For example, in a forest, dense foliage reduces the amount of light reaching the ground. This also results in a changed air temperature profile in a forest 12

13 Thermoregulation and Homeostasis Homoiothermic or endothermic animals (warm blooded) Poikilothermic or ectothermic animals (Cold-blooded) 13

14 Ecological Rule Allens rule: Warm blooded animals tend to have shorter extremities (ears, tails) in colder climates than they have in warmer climates Bergmann's rule: Larger body size in animals living in colder climates than those of the same group living in warmer climates 14

15 Ecological Rule Glogers rule: Warm blooded animals tend to have more pigmentations in warm, humid areas than in cool, dry area 15

16 Tolerance range Environmental conditions exist as gradients. Changes in the performance of an organism along such a trend are called environmental gradient There are upper and lower threshold values on the gradient beyond which the species cannot survive known as upper limit of tolerance and lower limit of tolerance The whole range over which a species is able to survive is known as range of tolerance Steno: Narrow tolerance Eury: Wide tolerance 16

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18 Ecological amplitude Different species differ from each other in terms of their demands from their environment and consequently also in respect to the extent to which they can tolerate the fluctuations in their environmental conditions. This range of demands and consequent range of tolerance of a species is known as its ecological amplitude. 18

19 Ecological Species Concept Ecotype: An ecotype is a population of individuals of a species which are genetically different. Different ecotypes of a particular species may differ in their edaphic, biotic or microclimate requirements. In ecotypes, adaptations become irreversible or genetically fixed Ecotypes are genetically adapted local populations Ecospecies: is a unit of classifications which contains one or more ecotypes. Ecospecies although interfertile but do not cross or at least do not produce viable offspring, if crossed with ecotypes of other species. 19

20 Ecological Species Concept Ecads: Also known as ecophenes. An ecad of a plant species is a population of individuals which although belong to the same genetic stock (genetically similar) but differ in vegetative characters such as size, shape, number of leaves, stem etc. They are genetically same but differ morphologically. Variations are environmentally induced and thus are temporary or reversible, one type of ecad may change into another with a change in its habitat. Ecads show phenotypic plasticity, i.e., environmentally induced phenotypic variation 20

21 Ecological equivalents: Organisms that occupy the same or similar ecological niches in different geographical regions. Species that occupy same equivalent niches and occur in widely separated regions are generally taxonomically much different. Ecological equivalents result from convergent evolution. For instance, sharks (fish) and dolphins (mammals) live in a marine habitat and superficially resemble each other. 21

22 Concept of Habitat and Niche Habitat is a place, niche a pattern of living The niche an organism occupies is the sum total of all the ways it utilizes the resources of its environment. A niche may be described in terms of space utilization, food consumption, temperature range, appropriate conditions for mating, requirements for moisture, and other factors Each habitat provides many different niches. The ecological niche is defined by first, the functional role of the species in its community (trophic position) and second, by its environmental gradients Niche is defined by n variables: Multidimensional hypervolume 22

23 Fundamental and Realized Niche Fundamental niche is the maximum theoretically inhabited hypervolume where a species can live,outer limits of its tolerance. Realized niche is a smaller hypervolume which is occupied by the species under interference from the competition of other species. 23

24 Gause and the Principle of Competitive Exclusion 24

25 Niche Overlap 25

26 Competitive Exclusion Gause s principle of competitive exclusion can be restated to say that no two species can occupy the same niche indefinitely when resources are limiting. Certainly species can and do coexist while competing for some of the same resources. Nevertheless, Gause s theory predicts that when two species coexist on a long-term basis, either resources must not be limited or their niches will always differ in one or more features; otherwise, one species will outcompete the other and the extinction of the second species will inevitably result, a process referred to as competitive exclusion 26

27 Resource partitioning 27

28 Resource partitioning is often seen in similar species that occupy the same geographical area. Such sympatric species often avoid competition by living in different portions of the habitat or by utilizing different food or other resources. This is also the example of Divergent Evolotion E.g. Darwin's Finches,Warbler 28

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