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+ Organisms and Populations
fF __OROAMIENS AND POPULATIONS “=
| RAMDEO MISHRA,
Prof. ler |__. reproduction
Survival -—[_organismic level
a
in & snow)
(a) Father of ecology in india
(2) National committee for environmental
Planning and co-ordination -1972 Rotation of earth > Variation in.
(2) Ministry of environment & forests - 1984 around sun annual
andtitof earth’saxis temperature "2"
‘at any level of biological organisation we can ask waar o°c Sub-zero ‘© Required by animals for
‘and seasonal variations
for foraging, reproducti
‘© EURYTHERMS ~ can tolerate wide range of temperature
STENOTHERMS ~ can tolerate narrow range of temperature.
+ Unique habitats: thermal springs and deep-sea hydrothermal vents migration.
(average temperatures exceed 100°C), © At depth > 500m in
+ Mango trees do not grow in temperate countries ke Canada and eee
Germany, snow leopards not found in Kerala, tuna fish are rarely caught
beyond tropical latitudes.
‘+ Temperature affects kinetics of enzymes and through it the metabolic
fe Red algae found in deepest wat, |
due to special pigments which |
‘can absorb lower wavelength of
wy sunlight.
AES aha RSET a
eal as en ot pe sty dpe | | ane ge te een
‘on water. nature and properties of soil.
© SALINITY —salt concentration in water. ‘© Percolation and water holding capacity determined by
[measured in ppt = parts per thousand) some characteristics of soil such as grain size, soi)
30-35 pptin sea © Vegetation and type of animals determined by pH,
Pacers ones wiraal cueotion and Scena
1¢ STENOHALINE -can tolerate narrow range of salinty || ® Sediment characteristics decide the type of benthic
ES eer
Organisms which cannot maintain constant internal environment eg. 99% of
animals and nearly all plants are conformers.
Body temperature and osmotic concentration changes with ambien
environment
Thermal regulation is energetically expensive process.
Heat loss or heat gains a function of surface area.
‘Small organisms have higher surface relative to volume and lose body heat very
fast when itis cold outside, that's why small animals ike shrews and humming
birds etc. ae rarely found in polar regions.
Some species have evolved ability to regulate over limited range of concitions|
beyond which they simply conform,
le Ablity to maintain homeostasis
(Mainly physiologically some
time behaviourally)
Je All birds, mammals, very few
lower vertebrates and
invertebrates
Jj Regulators are most successful
organisms of nature.
g
=
5
ES
2
Fs
{f stressful conditions are localized or remain only for short duration
MIGRATE SUSPEND mi
Temporary movement of| |e Formation of dormant structures like thick
lorganisms from _stressfull | Walled spores by bacteria, fungi, lower plants,
habitat to hospitable area.| |®FOrmation of seeds and other vegetative
Je.g. migration of birds from| | f@Productive structure by higher plants,
Siberia and cold northern| |e Hibernation by bears, e
Diagrammatic representation | regions to Keoladeo National| |¢ Aestivation by some snails and fishes. 4
of organismic response Park, Bharatpur (Rajasthan), | |® Oiapause by many zooplankton species.| &
Regulators
Partial regulators
Internal level >
External level>
intime
k.—$£——_____ i
jay organisms and Populations
ate othe organi (morpho ee
von aie loa, physiological & behavioural [that enables the orgasm tosurive and reprod sin habia
£
WORPHOLOGICAL REGS 1
_rickeuticle © Altitude sickness-cause by low 0; ea
|¢2 "sunken stomata
“Leave modified to spines
“Flattened stems
due to low Po, of high altitude ‘© Desert lizard-lack physiological
‘Symptoms => Nausea, fatigue, || ability
heart palpitations. aa att
Adaptations = Increased RBC nen
ote: production, decreased binding temperature is below
4. Polar seals ~ Thick ft layer (Blubber) snk aaa eon, comfort zone
increased breathing rate.
pelow skin to reduce heat loss, 8: Kangaroo rat in North American Moves into shade when
4 isabes found in hydrothermal | gees meet water requrement temperature starts
aig se by internal fat oxidation and
vents, fishes in antartic water and | concentrates urine to reduce increasing
freemen found in’ deep oceans |g Water oss . cies lke to burr
a © Allen's Rule Mammals in colder || ° Some SPedies lke to burrow
under very high pressure show | climate have shorter ears limbs to || to escape ground heat.
‘minimize heat loss,
© CAM pathway
biochemical adaptations.
Few examples of populations : All the cormorants in a wetland, rats in an abandoned dwelling, teakwood trees im
2 forest tract, bacteria in a culture plate and lotus plants in a pond.
Population ecology isan important area because it links ecology to population genetics and evolution
Birth rates Death rates [Sex ratio)
aE
(attributes of population )
[Age pyramid] Population density]
Measured in =
‘* Numbers (Most appropriate measure)
‘© Percent cover or biomass
© Relative densit
resis tive densities
Post reproductive
Reproductiveg
lpre-reproductive
Expanding Stable Declining ® Tiger census~ pug marks and fecal pellets
Population Density SS
Influenced Immigration
UW)
Normal condition Special condition ] a
ir like newly colonized area
Birth rates i roe
Death rates Immigration ata Densty | =| Morality
: f isnot (8) (N} ©)
Population growth : The size of a population for any species is not a (N)
Static parameter. It keeps changing with time, depending on :
1) Food availability (i) Predation pressure (ii) Adverse weather. Emigration
Growth Models ©
‘or unlimited resources, the population
# Exponential growth
‘grows in an exponential or geometric fashion ‘or}-shaped curve.
Noon =Ne# (+1) -(O+E))
aN/At = rN
='Intrinsic rate of natural increase
Ny= Noe” = Population density after time t
No Population density after time tero
£= Intrinsic rate of natural increase
sie base of natural logarithms (2.71828)
rowth (Verhulst-Pearl Logistic Growth):
for limited resources,
Carrying capacity (K)
This graph shows
(0) Lag phase
(©) Deceleration
(b) Phases of acceleration
(4) An asymptote
KN }
K
N= Population density at time t
Intrinsic rate of natural increase
Carrying capacity
Life History Variation
N/a
Where
Some organisms breed only once in their Metime, (Pacific salmon fi
{heir lifetime (most birds and mammals)
Some produce a targe num
large-sized offspring (birds, mammals)
ber of small-sized offspring (Oysters, pela
Population density (N) —»
Time (t) —
Population growth curve (a) when
responses are not limiting the
plot is exponential, (b) when response,
are limiting the growth, pot is logistic, x
is carrying capacity
sh, bamboo) while others breed many times during
8 fishes) while others produce 3 small number gp
Name of interaction
Mutualism
Species @
‘Species A
[Porutarion wrewacrons]
f
+
POSITIVE INTERACTIONS NEGATIVE INTERACTIONS
Eredation, parasitsm and commensatism share a common
haracterstc— the interacting species ive closely together.
Predation (+, -)
= Catch, kill and eat.
= Conduits of energy transfer.
= Keee Prey population under control eg Prickly pear
E2eUs controlled by moth in Australia (1920)
©. Biological control of pests in agriculture
Fredator maintains species diversity. eg. Removal of
Pater cause. etinction of >10° species or
invertebrates within a year,
= Predators are prudent in nature as they never over
exploit their prey population,
= Defence camouflage by frogs and insects,
= Prey can be poisonous and distasteful eg ‘Monarch
butterfly
Nearly 25 percent of all insects are phytophagous
(Feeding on plants)
= Plants show morphological defences eg Thorns/spines
(Cactus, Acacia).
= Plants show chemical
lycosides)
= Neatine, caffeine, quinine, strychnine, opium ete are
Produced as defence against grazers & browsers
defences, e.g. calotropis (cardiac
‘Competition
Predation
Parasitism
(commensal
‘Amensalism
Parasitism (+, -)
= Mode of lfe ensuring free lodging and meals
Poraites can be host specife and bath host and passe
coevolve,
~ Afatations of parasites adhesive organs or include lg
th
and high reproductive capacity,
Ue ‘vcs of parasites are often complex involving
cra aye StF vectors. eg. Human Iver uke rea
pralland fish, Malaria parasite needs mosquita,
> Brood parasitism : Parasitic bird lays 88 in nest of host
and hestincubate them eg. Cuckoo'® Cone
