Category 3 · Environment & Ecology

Population Ecology and Species Interactions

9 micro topics in Environment & Ecology for UPSC Prelims, in book order: Types of Species; Population Ecology and Population Growth Models; and 7 more.

1. 3.1

   Types of Species

   A species is a group of organisms that can interbreed in nature and produce fertile offspring, according to the biological species concept of Ernst Mayr. Ecologists classify species in many ways according to their origin, role…

2. 3.2

   Population Ecology and Population Growth Models

   Population ecology studies the size, density, structure and dynamics of populations of a species and the factors that change them. A population has attributes such as density (individuals per unit area), natality (birth rate), mortality (death…

3. 3.3

   Methodology of Tiger Census and Lion Census

   India estimates its tiger population every four years in the All India Tiger Estimation, AITE, conducted by the National Tiger Conservation Authority with the Wildlife Institute of India and state forest departments. The method has three…

4. 3.4

   Adaptation in Plants and Animals: Examples

   An adaptation is a feature of structure, physiology or behaviour that helps an organism to survive and reproduce in its environment, and which has been shaped by natural selection over generations. Adaptations are of three kinds:…

5. 3.5

   Homeostasis

   Homeostasis is the ability of an organism, and by extension a population or ecosystem, to maintain a relatively stable internal state in spite of changes in its external environment. The French physiologist Claude Bernard described the…

6. 3.6

   Interaction Between Species

   Species in a community interact in several ways, which are classified by the effect on each partner as positive, negative or neutral. Mutualism is a positive-positive relationship in which both partners benefit, as in lichens, mycorrhiza…

7. 3.7

   Ecotone

   An ecotone is the zone of transition between two adjacent ecological systems, such as a forest and a grassland, a river and the sea, or a pond and the land, in which the characteristics of both…

8. 3.8

   Endemic Species, Keystone Species, Indicator Species, Invasive Species

   Four kinds of species are often asked together. An endemic species is restricted to a particular geographic region and found nowhere else, such as the Nilgiri tahr and the lion-tailed macaque in the Western Ghats. A…

9. 3.9

   Allopatric and Sympatric Speciation

   Speciation is the evolutionary process by which one species splits into two or more new species. It depends on reproductive isolation, a barrier to gene flow between populations that allows them to diverge by mutation, natural…

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Frequently asked questions

Which topics are in Population Ecology and Species Interactions?

Population Ecology and Species Interactions has 9 micro topics in Environment & Ecology: Types of Species; Population Ecology and Population Growth Models; Methodology of Tiger Census and Lion Census; Adaptation in Plants and Animals: Examples; Homeostasis; Interaction Between Species; Ecotone; Endemic Species, Keystone Species, Indicator Species, Invasive Species; Allopatric and Sympatric Speciation.

Is Population Ecology and Species Interactions important for UPSC Prelims?

Population Ecology and Species Interactions is a part of the UPSC Prelims Environment & Ecology syllabus map on MaargX UPSC. Each of its 9 published topics has key terms, a Mains angle and practice questions.