GATE Ecology and Evolution Ecology Syllabus

Ecology syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Ecology in GATE Ecology and Evolution, not a summary of it.

1. 1

   Fundamental concepts

   3 topics

   • Abiotic and biotic components
   • Scales (population, species, community, ecosystems, biomes)
   • Niches and habitats
2. 2

   Population ecology

   3 topics

   • Population growth rates (density dependent/independent)
   • Metapopulation ecology
     • Colonization
     • Persistence
     • Extinction
     • Patches
     • Sources
     • Sinks
   • Age-structured populations
3. 3

   Interactions

   3 topics

   • Types (mutualism, symbiosis, commensalism, competition, parasitism, predation, etc)
   • Ecophysiology
     • Physiological adaptations to abiotic environment
   • Prey-predator interactions
     • Lotka-Voltera equation
4. 4

   Community ecology

   4 topics

   • Community assembly, organization and succession
   • Species richness, evenness and diversity indices
   • Species-area relationships
   • Theory of island biogeography
5. 5

   Ecosystems structure and function

   3 topics

   • Trophic levels and their interactions
   • Nutrient cycles
   • Primary and secondary productivity

Ecology flashcards for GATE Ecology and Evolution

23 of 50 cards from the Ecology deck — real questions with worked answers.

1. What are the two broad categories of components that constitute an ecosystem?

   Abiotic components (non-living physical and chemical factors such as light, temperature, water, pH, soil, and nutrients) and biotic components (all living organisms: producers, consumers, and decomposers).

2. Define a 'niche' in ecology and distinguish it from a 'habitat'.

   A niche is the total functional role of a species in its ecosystem (its use of resources, interactions, and conditions it tolerates), whereas a habitat is the physical place where an organism lives. Habitat is the 'address'; niche is the 'profession'.

3. Distinguish between the fundamental niche and the realized niche.

   The fundamental niche is the full range of conditions and resources a species could potentially use in the absence of competitors and predators. The realized niche is the actual, usually smaller, niche occupied once biotic interactions (e.g., competition) constrain it.

4. List the ecological scales of organization from smallest to largest above the individual.

   Population $\to$ Community $\to$ Ecosystem $\to$ Biome $\to$ Biosphere. (A species comprises interbreeding populations; biomes are large regional units defined by climate and dominant vegetation.)

5. What is a biome, and which two abiotic factors most strongly determine its distribution?

   A biome is a large geographic region characterized by a distinctive climax community and dominant vegetation type. Its distribution is governed primarily by temperature and precipitation.

6. Write the exponential (density-independent) population growth equation in differential form and define each term.

   $$\frac{dN}{dt} = rN$$ where $N$ is population size, $t$ is time, and $r$ is the intrinsic (per-capita) rate of increase. Growth is unlimited and J-shaped.

7. Give the integrated solution of the exponential growth equation.

   $$N_t = N_0 e^{rt}$$ where $N_0$ is the initial population size, $N_t$ is the size at time $t$, and $r$ is the intrinsic rate of increase.

8. Write the logistic (density-dependent) growth equation and define carrying capacity.

   $$\frac{dN}{dt} = rN\left(1 - \frac{N}{K}\right)$$ where $K$ is the carrying capacity, the maximum population size the environment can sustain. Growth is S-shaped (sigmoidal).

9. At what population size does the logistic growth curve show the maximum growth rate?

   At $N = \frac{K}{2}$, where the rate $\frac{dN}{dt}$ is maximized (the inflection point of the sigmoidal curve).

10. Distinguish density-dependent from density-independent factors regulating populations.

    Density-dependent factors (e.g., competition, predation, disease, parasitism) exert effects whose intensity changes with population density. Density-independent factors (e.g., temperature, floods, drought, fire) affect populations regardless of density.

11. What is the relationship between $r$ and the per-capita birth and death rates?

    $r = b - d$, where $b$ is the per-capita instantaneous birth rate and $d$ is the per-capita instantaneous death rate. When $b > d$, the population grows.

12. Define a metapopulation.

    A metapopulation is a set of spatially separated local populations (subpopulations) of the same species occupying discrete habitat patches, connected by dispersal/migration, with local extinctions and recolonizations occurring over time.

13. Write the classic Levins metapopulation model and define its terms.

    $$\frac{dp}{dt} = cp(1-p) - ep$$ where $p$ is the fraction of patches occupied, $c$ is the colonization rate, and $e$ is the extinction rate.

14. In the Levins model, what is the equilibrium fraction of occupied patches?

    $$\hat{p} = 1 - \frac{e}{c}$$ The metapopulation persists only when $c > e$; if $e \geq c$, all patches eventually go extinct ($\hat{p}=0$).

15. Distinguish 'colonization', 'persistence', and 'extinction' in metapopulation dynamics.

    Colonization is the establishment of a new local population in an empty patch via dispersal; persistence is the continued survival of a local population over time; extinction is the loss of a local population from a patch.

16. Define a source population and a sink population in source-sink dynamics.

    A source is a high-quality patch where local births exceed deaths (net reproductive rate > 1), exporting emigrants. A sink is a low-quality patch where deaths exceed births (net rate < 1), persisting only via immigration from sources.

17. What is the demographic criterion distinguishing a source from a sink patch?

    In a source, per-capita birth rate exceeds death rate ($b > d$, net growth $> 0$) and it exports individuals. In a sink, $b < d$ (net growth $< 0$); it would go extinct without immigration.

18. What is a 'patch' in landscape and metapopulation ecology?

    A patch is a discrete area of suitable habitat surrounded by a matrix of unsuitable habitat, capable of supporting a local population. Patch size and isolation strongly influence colonization and extinction rates.

19. What does an age-structured population describe, and why is it important?

    It describes the distribution of individuals among different age classes. Age structure determines reproductive potential and future growth, since birth and death rates are age-specific.

20. Name the three general shapes of age-structure (population) pyramids and what each indicates.

    Expanding (broad base) = rapidly growing, young population; Stable/stationary (roughly even) = constant population; Constrictive/declining (narrow base) = shrinking population with more older individuals.

21. In a life table, what do the symbols $l_x$ and $m_x$ represent?

    $l_x$ is survivorship: the proportion of the original cohort surviving to age $x$. $m_x$ (or $b_x$) is the age-specific fecundity: the average number of offspring produced per individual of age $x$.

22. Write the formula for net reproductive rate $R_0$ from a life table and interpret it.

    $$R_0 = \sum_x l_x m_x$$ It is the average number of offspring per individual per generation. $R_0 > 1$ means growth, $R_0 = 1$ replacement, $R_0 < 1$ decline.

23. Name the three idealized survivorship curve types and give an example organism for each.

    Type I (low juvenile mortality, high late mortality — e.g., humans, large mammals); Type II (constant mortality across ages — e.g., many birds, rodents); Type III (high juvenile mortality, few survive to adulthood — e.g., many fish, invertebrates, plants).

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