Ecology Answers

8/13/2019 Ecology Answers

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UNIT I

Autecology- It deals with the study of the individual organism or an individual species in relation to the environment

- The term Autecology was coined by Schroter in 1896.

- It includes the study of life history, population dynamics, behavior, home range and so on.

- This has a great significance in economic biology such as fish culture, prawn culture, pearl culture etc.

- Herdman in 1896 indicated the economic possibilities of scientific agriculture. - Autecology is experimental and inductive.

Synecology- It deals with the study of groups of organisms which are associated together as a unit (i.e., communit

or entire ecosystems).

- This term was coined by Schroter and Kirchner in 1896.

- It includes the study of caves, deserts, deep sea system or tropical forests.

- This study involves the overall energy and material flow through the system rather than concentratin

on the finer details of a particular organism.

- Synecology is philosophical and deductive.

Abiotic Factors- The non-living environmental factors both physical and chemical factors are called Abiotic factors.

Ex: light, soil, water, air, temperature, carbon-di-oxide, other gases etc.

- These factors exhibit diurnal, nocturnal, seasonal annual changes.

- It is categorized into 3 types namely climatic factors, topographic or physiographic factors and edaphi

factors.

Biotic Factors- The living organisms present in the environment are called as Biotic factors

Ex: plants, animals and microbes

- These biotic factors are all interact in a fundamentally energy dependent fashion.

Soil Profile- The horizontal sequential arrangement of different layers of soil is termed as Soil Profile.

- The horizontal layers are called Horizons.

- In general soils have five horizons – O-horizon, three mineral horizons (A, B, C) and D-horizon.

Pedogenesis- The process of soil formation from rocks is called Pedogenesis.

- The rocks which are used for the formation of rocks are called as the soil forming rocks or the parenmaterial.

- The soil forms due to continuous disintegration of rocks.

- Weathering forces like wind, chemical and biological changes create rapid disintegration of rocks whos

results in creation of soil.

Soil Erosion- it refers to the loss or removal of the top layer of the soil by the action of wind, water, ocean waves

glaciers and human activities.

- It results in the loss of soil fertility.



Soil Conservation

- Soil conservation means protection, maintenance, improvement and sustained renewal of the soil an

its fertility at any place.

- It tends to increase the soil fertility.

Biogeochemical Cycle

- The cyclic movements of chemical elements (biogenetic nutrients) of the biosphere between th

organism and the environment are referred to as biogeochemical cycles, after Vernadsky (1934). - “Bio” refers to living organisms and “geo” to the rocks, soil, air and water of the earth.

- It is also called as the Nutrient Cycle.

- There are two types of biogeochemical cycles, the gaseous and the sedimentary.

Historical Views on Ecology

- In the fourth century B.C. Aristotle made references about the habits of animals and environmenta

conditions prevailing in certain areas, in his writings on natural history.

- Buffon considered that animals and plants developed adaptations which enabled them to favorabl

respond to their environment and termed this environmental induction.

- In 1841 Doubleday brought out his true law of population.

- Richard Bradley (1969) recognized the fundamental similarities of animal husbandry and production.

Phototropism

- The effect of sunlight on the plant movement is called heliotropism or phototropism.

- The stems elongate towards light (positive phototropism) and

- The roots are negatively phototropic. The leaves grow transversely to the path of light.

Photoperiodism

- The response of different organisms to environmental rhythms of light and darkness is terme

photoperiodism.

- Each daily cycle inclusive of a period of illumination followed by a period of darkness is called th

photoperiod.

- The term photophase and scatophase are sometimes used to denote the period of light and the perio

of darkness respectively.

UNIT II

Environment

- The environment is the sum total of physical and biotic conditions influencing the responses of the

organisms.

- The word Environment comes from French word “Environ” which means “Surrounding”.

- Thus Environment refers to our surrounding and variety of issues related to human activities and its

impact on nature.



Environment Conservation- Conservation of Environment is concerned with the proper management and maintenance of natural

resources like land, water, forest, sea, mines etc. for the benefit of human beings.

Natality

- Natality is a broader term covering the production of new individuals by birth, hatching, germination, o

fission. The natality rate may e expressed as the number of organisms born per female per unit time. Ihuman population, the natality rate is equivalent to the ‘birth-rate’.

Mortality

- Mortality means the rate of death of individuals in the population. It is a negative factor for population

growth.

- Minimum mortality: It is also called specific or potential mortality. Minimum mortality represents the

theoretical minimum loss under ideal or non-limiting conditions. It may be constant for a population.

- Ecological mortality: It is also called realized mortality. It is the actual loss of individuals under a given

environmental condition.

Interspecific Interactions- Organisms do not exist alone in nature but in a matrix of other organism of many species. The

interactions between individuals of one species to that of individuals of another species is known as

Interspecific interactions.

- It is of two types

Positive Interactions

Negative Interactions

Intraspecific Interactions- If the interactions between the organisms of the same species. The individuals generally have many

types of intraspecific interactions.

EX: Associations between individuals of same species, social life, aggregation etc.

Ecological Density

- Ecological density (also called specific or economic density) is the density (number or biomass) per uni

of habital space, i.e., available area or volume that can actually be colonised by the population. In

nature, organisms grow generally clumped into groups and rarely are uniformly distributed.

Mutation

- Mutualism is an obligatory positive interspecific interaction that is strongly beneficial to both species. In

past, it was termed symbiosis.

- In mutualism, two populations enter into some sort of physiological exchange and resulted in

coevolution of both species

- In this case, both of the species derive benefit and there exists a close and often permanent and

obligatory contact which is more or less essential for survival of each.

EX: Mycorrhizae in association with the roots of higher plants.



Commensalism

- Commensalism defines the coaction in which two or more species are associated and one species at

least, derives benefit from the association, while the other associates are neither benefited nor harmed

- The concept of commensalism has been broadened in recent years, to apply to coactions other than

those centering on food; cover, support, protection, and locomotion are now frequently included. EX: Escherchia coli is found in human colon.

Proto cooperation- An interaction between organisms that is mutually beneficial but not obligatory to those participating,

not applicable to conscious cooperation of human beings.

EX: Sea anemone ( Adamsia palliata) attached to the empty molluscan shell harbouring hermit crab (Eupagurus

prideauxi ).

Parasitism- This is the interaction or Coaction in which one or more organisms.

- The Parasite infects or affects and benefits by feeding upon the other organisms, the hosts.

- Often the term is restricted to nutritive relations.

EX: Tapeworm in human intestine.

Amensalism- The state or interaction in which one organism is inhibited while the other is not influenced.

- Amensalism is a situation in which one population definitely inhibits the other while remaining

unaffected itself.

EX: Salvia leucophylla leaves emit some volatile oils which reach the soil surface and inhibit the germination of

seeds of other species and the inhibitory effects persist for several months.

Hardy Weinberg Law

This law states that

“The gene and genotype frequencies in a mendelian population remain constant generation afte

generation if there is large population, random mating and in the absence of selection, mutation, migration o

genetic drift”.

- Evolution Occurs only when Hardy Weinberg equilibrium is altered.

- This law is represented by the formula

p + q = 1

Gene Frequency- The ratio of one allele to other alleles in a gene pool or a population is called Gene Frequency.

(OR)

The proportion of one allele in the gene pool to the other alleles of the same locus is called Gen

Frequency.

- Gene frequency helps to estimate the number of genes in population or gene pool.

- It also helps to observe the number of genes changed in the population.

Genotype Frequency

- The exact number of genotypic individuals (heterozygous individuals) present in a given population

EX: In hardy Weinberg law of equilibrium the ‘pq’ represents the heterozygotic population.



Mutation

- A spontaneous permanent change in a gene or chromosome which usually produces a detectable effec

in the organism concerned and is transmitted to the offsprings.

- It is the ultimate source of variations.

- Some are selectable while others are non-selectable.

Gene Flow- The movement (sharing of genes) of alleles from one population to another during interbreeding i

called Gene Flow.

- It happens when an animal population moves from one habitat to another.

Non Random Mating

- Mating is a selective process, hence mating does not occur at random naturally.

- It will affect the Hardy Weinberg’s law of Equilibrium.

- In non-random mating process the frequency of heterozygotes in the population will decreas

generation after generation.

- It results in an abundance of certain genotypes at the expense of other genotypes.

Genetic drift- Genetic Drift refers to changes in gene frequency brought about, purely by chance in small populations

- It is an evolutionary force naturally operating in small populations.

- It produces variations in small populations.

- It was explained by Sewall Wright, hence it is also known as Sewall Wright Effect.

Selection- The fitness or unfitness is decided by the environment, the nature. So the environment acts as the

selecting force.- It selects those organisms which are provided with favourable variations.

- This process of selection of organisms with favourable variations is called Natural Selection

EX: Evolution of Long Neck in Giraffe.

UNIT III

Community-

A mono specific assemblage of living organisms is a population. An assemblage of different kinds of

populations living in a defined area or habitat is called a Biotic Community. It is a complex assemblage

of microbial, plant and animal communities.

Community Diversity- Various species of plants and animals live in a community and exhibit species richness or species diversity or

community diversity.

- The study of species diversity is an essential component of community study.

- A community contains a few individuals of many species will have a higher diversity than will a communitycontaining the same number of individuals but with most of the individuals confined to a few species.

Stratification



- Stratification of biotic communities involves the formation of distinct strata or layer by the organisms.

- Organisms are distributed unevenly throughout the biotic community, resulting in stratification.

- The stratification in community may be horizontal or vertical and is different in aquatic and terrestrial

habitats.

Ecotone- The transition zone between two or more diverse communities or biomes is called the ecotone.

Ex: The border between forest and grassland, the bank of a stream running through a meadow or between asoft bottom and hard bottom marine community.

Edge Effect

- The potential for the ecotone to act as habitat for species found in neither major community is termed

as the edge effect.

Ecological Succession- The development of the community by the action of vegetation on the environment leading to the

establishment of new species is termed Ecological Succession.

(Or)

- The replacement of one community by the other kinds of communities in course of time due to change

in physical conditions is called Ecological Succession.

Food Chain

- The transfer or flow of energy from one trophic level to other in succession in an ecosystem.

- The patterns of eating and being eaten forms a linear chain called Food Chain, which can always be

traced back to the producers. Ex: Sun Grass DeerTiger

Food Web

- In a given ecosystem various food chains are linked together and intersect each other to form a comple

network called food web.

- In nature simple food chains occur rarely. The same organism may operate in the ecosystem at more

than one trophic level, i.e., it may derive its food from more than one source.

EX: Tiger Fox Rabbit Hawk------- Snake

Deer ------- Grass Grasshopper Frog

UNIT V

Resource Management- Natural resource management is the taking care or management of natural resources such as land

water, soil, plants and animals with a particular focus on how management affects the quality of life fo

both present and future generations.

- It deals with managing the way in which people and natural landscapes interact.

Renewable Resources



- Renewable natural resources are the ones which can be replenished, reproduced or recycled easily.

- It is the unending sources of energy.

Ex: water, soil fertility, forests, agricultural crops, etc.

Non Renewable Resources- Non-Renewable resources are those whose resources cannot be replaced or recycled after their use.

Ex: Petrol, Coal, Crude oil, etc.

Conservation of Resources- It is the prevention and proper management of natural resources from loss, degradation, waste, fire an

destructive influences to use it back.

- Conservation has been defined as “the management for the benefit of life including human kind of th

biosphere so that it may yield sustainable benefit to the present generation while maintaining it

potential to meet the needs and aspirations of the future generations.” (P.S. Verma., V.K. Agarwal)

Ex: Conservation of wildlife, minerals and fossil fuels.

Wildlife Depletion:- It is the slow reduction of wild animals and plants and move towards extinction due to destructio

made by human and natural activities such as, deforestation, hunting, floods, cyclones, urbanization

etc.

Sanctuaries:

- Sanctuaries are places where the killing or capturing of any animal is prohibited except under orders o

the authorities concerned. They provide protection and optimum living conditions to wild animals.

Ex: Mundanthurai sanctuary, Vedanthangal bird sanctuary, Guindy deer park.

Green House Effect- The earth’s surface absorbs the solar radiation and radiates in the form of Infra-red radiation.

- Some part of the IR radiation is absorbed by the atmospheric gases like CO2, CH4, CFC, O3,N2O etc.

- It reemits the radiation back to earth’s surface which becomes heated up.

- This phenomenon is called GREEN HOUSE EFFECT.

Ozone Layer- It is also called Ozone Umbrella and composed of O3 (Ozone) in the stratosphere.

- It gives protection from UV rays, other IR rays from entering the earth’s surface.

- Thus by absorbing these radiations this layer is of increased temperature.

- The sunlight ionizes the oxygen to ozone by photochemical dissociation.

Air Pollution- The process of polluting the air (either naturally or manmade) with pollutants like solid particles, liqui

droplets and vapor (other than the atmospheric gases) in sufficiently excess amount to harm the huma

beings.

Ex: Dust, Smoke, Arsines, Ammonia, Carbon monoxide, etc.

Water Pollution



- It is defined as “ a change in the quantity or composition of wat er directly or indirectly as a result o

man’s activities, so that it becomes unsuitable for drinking, domestic, recreational and agricultura

purposes”.

Ex: pollution of water bodies such as rivers, ponds, lakes and seas by the sewage or by industrial chemicals.

Soil Pollution- It is defined as “a desirable change in the natural, physical, chemical or biological components of th

soil, dumping urban waste matter, dumping of industrial waste, mineral exploitation and harmfu

agricultural practices”.

- Soil pollution reduces the fertility of the soil and its characteristics.

Disaster Management- It is the management or handling of the environmental disasters such as earthquake, floods, tsunam

etc., happened in a particular area.

- It is the body of policy, administrative decisions and an operational activity which pertain to the variou

phases of a disaster.

- It includes prediction of the occurrence, prevention, resettlement, rehabilitation of disasters

Earthquake- An earthquake is a sudden motion or trembling of the ground produced by abrupt displacement of roc

masses.

- It is a series of vibrations on the earth’s surface caused by the generation of elastic waves due t

sudden rupture within the earth during the release of accumulated strain energy.

- The study of earthquake is called Seismography.

Cyclones- The word cyclone is derived from the Greek word ‘cyclos’ meaning ‘coils of a snake’.

- Cyclones are ragging spirals of wind and rain that are born near the equator over the sea, creating a

area of low atmospheric pressure with a series of closed isobars around its centre.

Landslides- A sudden flow or slipping of soil and rock or rock pieces under the influence of gravity from a hilly, dow

slope area.

- They are caused due to the disturbance of the equilibrium between stress and strength of material o

slope.

- Depending upon the nature of materials fallen from the slopes it is known to be rockslide (sliding o

rocks), landslides (sliding of a portion of land) and avalanches (snow and ice).

Tsunami - It a Natural Disaster caused due to the abnormal changes in the earth plates.

- The tsunami is a Japanese word meaning ‘harbour waves ’ (Tsu=harbor; nami=waves)

- This disaster is featured with the huge oceanic waves which will destroy a particular environment.

Global Warming- Gradual rise in atmospheric and ground surface, air, temperature and consequent change in globa

radiation balance caused mainly by anthropogenic progress leading to climate change at differen

levels.

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