Habitat & niche

Surendra patel

1. K.G. ARTS & SCIENCE COLLEGE RAIGARH (C.G.) Year - 2019-20 Deparment of zoology & research center Subject :- Environmental physiology & ecology Seminar topic:- Habitat & Niche concept Guided by:- Submitted by:- Prof. Vinita Pandey mam. Surendra Patel M.Sc sem I zoology

2. SYNOPSIS :- 1. Introduction 2. History 3.Types of habitat 4.Types of niche 5. Niche breadth & overlap 6. Diffirence between niche & habitat 7. Concepts & principals 8. Conclusion 9. Refrences

3. INTRODUCTION :- Habitat refers a place, where an organism or a species population lives. For example - a pond is a habitat of zooplankton, phytoplankton and fish. And the role of an organism in its environment is called niche. Niche denotes the working place of an organism. Habitat can be similler for some organism but niche is different. For example - a lake is a habitat of all type of fish whose niche are diffirent they may be carnivorous, herbivorous or omnivorous fish depending on their food habitat.

4. 2. HISTORY :- ● Joseph Grinnel (1917) coined the word niche to denote the microhabitat, where the organism lives. ● Charles Elton (1927) regard the niche as the fundamental unit of an organism. ● Kendeigh (1974) considerd the niche as a combination of the habitat and biotic intraction of a species for it’s survival and continuence in a community.

5. 3. TYPES OF HABITAT :- As we all know, habitat is a place where the organism live. Habitat may be divided into many types such as terrestrial, aquatic etc. (A) Terrestial :- A terrestial habitat may comprise forest, grassland, tundra, desert and so on. Forest habitat :- It is characterised with trees, mostly above 8 meters. The forest community may be evergreen, decideous, high and low.

6. (ii) Grassland habitat :- This habitat is consists of grass and herbaceous plants. The majority of them being graminoid. (iii) Desert habitat :- In this habitat mostly succeulant plants are found. The tempreture of this region is very high. (iv) Tundra habitat :- It consists of very low woody vegitation.

7. (B) Aquatic habitat Fresh water : - Species found in fresh water like river, lake,pond etc is called fresh water species and this type of habitat is called fresh water habitat. Saline water :- Species found in marine water like ocean,sea is called saline water species and this type of habitat is called saline water habitat.

8. 4. Types of niche :- The ecological niche may have 3 types :- Spartial/habitat niche :- As the name indicates the spartia niche is concerned with the physical space occupied by an organism. It is broadly related to concept of habitat, but differ from it in the sense that while different species may occupy the same habitat and the area is very large where an organism live. The activities of each organism may actually be confined to only a small portion of habitat called microhabitat.

9. (B) Trophic niche :- This refers to a trophic position (food level) of an organism. For example – in the Galapagos island in South Africa birds belonging in 3 genera namly Geospiza (ground finches), Camarhynchus (tree finches), and Certhidia (warbler finches) are found. All the birds live in same habitat but differ in their trophic level. The Camarhynchus (tree finches) has a parrot like beak and feeds on buds and fruits. And the other two are carnivorous and feeds on insects of diffirent size.

10. (C) Hypervolume/ Multidimensional niche :- The concept of hypervolume or multidimentional niche was developed by Hutchinson 1965. He recongnised two type of niche :- Fundamental niche :- The fundamental niche is the maximum abstractly inhibited hypervolume, when the species is not competing with others for its resources.

11. (ii) Realised niche :- An indivisual or a species normally remains in competition (either interspecies or interspecies or both) and thus under biotic constraints only a part of the niche is realised by the species. This smaller hypervolume occupied by a species called the realised niche.

12. 5. Niche breadth and overlap :- Niche breadth :- Niche breadth may refers to the width of the area. The species that utilised a broad spectrum of the environment are called habitat generalists. They usually have high niche breadth score. Some species are restricted in their distribution and live in a narrow range of environmental spectrum. They exibits low niche breadth score.

13. Niche breadth of each species can be calculated using Levine’s formula (1967) :- 1/Bj = € P2 ij Where :- Bj = niche breadth of species j and P ij = proportion of occurance of species j in plot i

14. (ii) Niche overlap :- Niche overlap is a measure of the association of two or more species. In other words, how often any two species occured together in a habitat or ecosystem. A high niche overlap value of two species indicates that they are found together more often than other species in a particular habitat. This indicates their similler habitat requirment and may also indicate competition if trophic or spartial niche is same food or space is limiting.

15. Horn’s (1966) formula can be used to calculate niche overlap score of each species :- Ljk = 2€ Pij Pik/ (€P2 ij + €P2 ik) Where :- P ij = Population of occurance of species ‘j’ in plot ‘i’ L jk = over lap of species, ‘j’ , ‘k’ & P jk = population of occurance of species ‘k’ in plot ‘i’

16. 6. Difference between habitat & niche :-

17. 7. Concepts & principals : - (i) Hypervolume concept :- This concept is based on the realationship between a species and the environment gradients. For example :- if we measure the range of environmental temperature over which a particular species can live and reproduce and do the same for another gradient like humidity, and then plot this realationship on graph, we obtain an enclosed space representing the niche of the species. Since two environmental factors are considerd

18. the niche is considerd to be two – diamensional. It will be multi dimesional if more than two environmental variabels are taken into account.

19. (ii) Gause’s completitive exclusive principal :- GF Gause (1934) conducted laboratory experiments on co-existance amoung closely related spicies of protozoa and on the basis of the result, he concluded that “no two species with identical niche requirments can co-exist.” This is defined as if two non interbreeding species population occupy exactly the same ecological niche(niche overlap is completed or near complete) the competition will be so serve that one species will be lose in the competition and looser speciesusually exhibits retarded growth and

20. may either leave that niche or become extinct. (iii) Thomas Park (1948,54) conducted a species of laboratory experiment on two species of flour beetle. Tribolium canfusum & T castaneum and found that when they grow together their survival depend on environment condition of tempreture and realated humidity.

21. 8. Conclusion :- A  habitat  defines the interaction of organisms with the other factors, which can be living or non-living, while niche  describes how that specific organism is linked with its physical and biological environment.  Habitat  is the part of the ecosystem, while  niche plays an important role in the formation of an ecosystem. 9. Refrences :- Fundamental of Ecology – M. C. Dash Ecology and environment – P. D. Sharma