This document discusses key concepts in ecology including organism level, population, biome, niche, adaptation, and population interactions. It defines population as a group of organisms of the same species that can interbreed. Biomes are characterized by dominant vegetation and formed due to variations in light, temperature, and precipitation. Organisms respond to abiotic factors through regulating, conforming, partial regulating, migrating, or suspending activities. Adaptations help organisms survive in different environments like deserts and high altitudes. Population interactions include predation, competition, parasitism, commensalism, and mutualism. Population growth can be exponential or logistic depending on resource availability.

1. ORGANISM AND POPULATION
Dr R K UPADHYAY

2. Ecology
study of interaction in between
biotic and abiotic components of
an ecosystem.

3. Organism level of ecology
ORGANISM
POPULATION
COMMUNITY
BIOME
NICHE
BIOSPHERE

4. Population
Group of organisms of same types and
potential to interbreed among themselves and
produce fertile progenies.

5. Biome
“ complexes of community that extend over a large
geographical area “
it is characterized by a dominant vegetation
Desert
Grass land
Conifer forest
Arctic alpine tundra
Temperate forest
Tropical forest

6. Components of ecosystem
Biotic
Living organisms
Abiotic
Temperature Water
Light Soil

7. Response to abiotic components
Conformers
Regulators
Partial regulators
Migrate
Suspended- hibernation, aestivation, dapause

8. Adaptation
In kangaroo rat
In xerophytic / desrt plants
In mammals (Allen’s rule)
In high altitude animals
In desert lizard
In Hydrophytic plants
In Halophytic plants

9. Niche
• It is not a place but the conceptual volume
with numerous dimensions. Eg- temperature,
humidity etc
• It represents the range of conditions that it
can tolerate, the resources it utilizes and its
role in ecosystem.

10. Biosphere / environment
• Biosphere – it is surface of earth with
all life forms
• Environment- sum total of external
conditions ( biotic + abiotic) which
influence the organisms.

11. Q 1- reason for change in season?
Q 2- different biomes are formed due to ?
Ans 1- i) due to rotation of earth around
sun
ii) Due to tilting of sun on its axix
Ans 2- i) annual variation in light intensity,
temperature
ii) annual variation in precipetation

12. Abiotic / physicochemical components
1- Temperatre-
Eurythermal- toleratein wide range of temp.
Stenothermal- tolerate in narraw range of temp.
2- Water –
Euryhaline- tolerate in wide range of salinity
Stenohyaline- tolerate in narraow range of salinity
Light- source of enegry, PS
Soil-

13. Response to abiotic components
• Regulate- homeostasis is maintained by constant
body temperature and constant osmotic conc.
• By process of sweating , shivering etc
eg. Birds, mammals, few lower invertebrates
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• conformers- body temp changes with the ambient
temp.
- osmoconformer- change osmotic conc according to
environment

14. Q – shrews and humming birds are
rare in polar reason why?
Ans- have large surface area in relation to their
volume so they loose heat very fast. Therefore
they are very rare in polar region .

15. Migrate
• Temporary movement of organisms from
unfavorable/ stressed habitat to the
favorable/ normal habitat.
eg. Migration of of birds

16. Suspend

17. Adaptation
• Any change in structure or functioning of
offsprings of a population that makes it better
suited to its environment is known as
adaptation.

18. Examples of adaptation
1- Kangaroo rat- found in North America desert
- Obtained water by fat oxidation
- Concentrates its urine
2- desert plants-
- Roots grow very deep
- Sunken stomata
- CAM pathway of PS (it enables the stomata to
close in day while it open in night)
- Leaves converted in to spines
- Thick cuticle

19. Mammals
Allen’s rule
- Shorter ear and limbs help in minimising heat loss
- Layer of fat (bubbler) below skin in polar bear, seals

20. High Altitude animals
• Increase in RBC
• Increase in breathing rate
• Decreased binding affinity of Hb

21. • Desert lizard-
• Absorb heat from sun when temp lowers
- Move into shade when temp starts rising
hydrophyte plants-
- Wax coating
- Roots are absent
Halophytic plants-
- Pnumatophores
- Vivipary- seed germinates while the fruit is still
attached to the plants. Eg rhizophora

22. Questions
1- when and why do some organism hibernate. Give
2 example
2- how does kangaroo rat fulfill its water need?
3- what are anti-frozen proteins which enable the
polar organism to live their?
4- make fig- diagrammatic representation of
organismic response and biome distribution with
respect to annual temp and rain fall.
5- mention adoptation in- camel, mangrooves, lotus,
cactus, CAM plants

23. Population attributes
• Natality (birth rate)
• Mortality (death rate)
• Density
• Sex ratio

24. Age pyramid- stable, expanding, declining
• When the age distribution is plotted for a
population, this is called age pyramid.
• It consists of – pre reproductive, reproductive and
post reproductive population
• Types- 1- expanding- pre reproductive are more
than reproductive and post reproductive are least
2- stable- pre reproductive and reproductive and
are about same and post reproductive very
less
3- declinig- pre reproductive are more less than
reproductive and post reproductive are less

25. Population growth
• It depends on- food availability, predation,
weather
• Density of population fluctuates due to –
1- natality- (+)- B
2- mortality- (-)- D
3- immigration- (+)- I
4- emigration- (-)- E
Population at time ( N t+1)-
N t+1 = Nt + (B+1)- (D +E)

26. GROWTH MODELS
EXPONENTIAL GROWTH-
The unlimited availability results in population
exponential growth
Nt= No ert
Nt= population density after time ‘t’
No- population density at time begening
r= intrinsic rate of natural increase
e= base of natural logarithms

27. Population growth curve showing exponential growth ( j shape)
• Dn/ dt = r N
N K
time (t)

28. K (carrying capacity
A given habitat have enough resources to
support a maximum possible number, beyond
which no further growth is possible. This called
carrying capacity (K)

29. Logistic growth curve (Verhulst- Pearl
curve)- Sigmoid curve/ S -shaped
N
‘K’ dN/ dT= rN K-N/ (K)
t

30. Q- Which one model is realistic J
shaped or S shaped and why?
• ‘S ‘ shaped is more realistic.
• No population growth can sustain exponential
growth indefinitely as there will be compition
for the basic needs.

31. Population interaction
• Predation
• Competition
• Parasitism
• Commensalism
• Mutualism

32. SPECIES ‘A’ SPECIES ‘B’ NAME OF INTERACTION
+ + MUTUALISM
_ _ COMPETITION
+ _ PREDATION
+ _ PARASITISM
+ 0 COMMENSALISM
_ 0 AMENSALISM

33. PREDATION – predator kills prey
- Importance of predators-
• Keep prey population under control
• Reduce competition among the prey
• Maintain species diversity

34. Prey defense mechanism
prey
species
evolve
various
defense
mechanism
Camouflage
(colour
change) to
avoid being
detected
some
produces
poisonous
chemicals
like cardiac
glycosides,
nicotine,
quinine etc
against
herbivores
Some are
very
distasteful-
eg Monarch
butterfly
Some have
thorns eg.
Acacia

35. COMPETITION – when closely related app compete
for the same limited resources
- Both species suffer
- Interspecific competition- with other spps
- Intraspecific competition- with in spps
- Example interspecific competition- in Galapagos
island when Goats were introduced, the tortoise
become extinct with in decade due to greater
browsing capacity of the goats.

36. Example- competition
Connel’s elegant field experiments-
On the rocky sea coasts of Scotland, the larger and
competitively superior barnacle Baranus dominates
the intertidal area and excludes the smaller
barnacle Chathamalus from that zone.
GAUSE’SCOMPETITIVE EXCLUSION PRINCIPLE- two closely
related spps competing for the same resources can not
co-exist indefinitely and competitively inferior one will be
eliminated eventually.

37. RESOURCE PARTITIONING
if 2 spps competes for the same resource,
they could avoid compaction by choosing for
instance, different times of feeding, different
foragging patterns
Example-
Mc Arthur - - 5 closely related spps of warblers living
on the same tree were able to avoid competition and
co exist due to behavioral differences in their foraging
pattern.

38. Parasitism – parasite depends on host
Types of parasite-
1- ECTOPARASITE- lice on humans, ticks on dog
2- ENDOPARASITE- liver fluke, plasmodium,
Salmonella typhi
3- BROOD PARASITISM- parasite lays its egg in the
nest of anopther organism. Eg- eggs of cukko
(koel)lays its egg in crows nest

39. Commensalism – one spp is benefitted
other is not affected
Examples-
1- EPIPHYTE- Orchid grows on mango tree
for shelter and nutrition
2- Barnacle growing on the back of whale
to move to different places for food
3- Clown fish find shelter in between
tentacles of sea anemone and get
protected by predators

40. MUTUALISM – both are benefitted
Examples-
1- lichen
2- Mycorrhiza
3- Pollination
4- Female wasp uses fruit for egg laying site and
developing seeds with in fruit for nourshing its
larvae.
5- Sexual deceit- Mediterranean Orchid, Ophrys to
get pollinated by spp of bee, one petal of its flower
resembled to the female of bee. Bee pseudo
copulate with orchid plant and help in pollination.

41. Questsions
1- what does S- shaped pattern of population growth represents? How
is J shaped pattern different from it and why?
2- list any 3 prosperities of population and explain.
3- explain diagrammatically the different age structures.
4- name important defense mechanism in plants against herbivore.
5- with the help of suitable diagram describe the logistic population
growth curve.
6- Give the expression for the change in population size.
7- an orchid plant is growing on the branch of mango tree. How do you
describe this interaction between the orchid and mango tree?
8- what do you mean by brood parasitism? Give one example.
9- differentiate between- commensalism and mutualism, population
and community, natality and mortality.
10- make a graph showing relation between regulators, conformers
and partial regulators.