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1. SURVIVAL
STRATEGIES

2. Dormancy
 Dormancy is a period in an organism's life cycle when
growth, development, and (in animals) physical activity are
temporarily stopped.
 It is a period of reduced metabolic activity that is adopted by
various organisms under strenuous conditions.
 Dormancy helps these organisms conserve energy.
 Most organisms synchronize their entry to the dormancy state
with the environmental changes via consequential or
predictive means.
 Consequential dormancy takes place when an organism
enters the dormancy state after the harsh conditions have
started.
 Predictive dormancy occurs when they enter the dormancy
phase right before the unfavorable conditions begin.

3. Types of dormancy
 Hibernation,
 Diapause,
 Aestivation, and
 Brumation.

4. Hibernation
 Hibernation is a phase of metabolic depression and inactivity
in endotherms.
 Hibernation is characterized by The following
 low metabolic rate,
 reduced heartbeat (by up to 95%),
 slow breathing, and
 low body temperature.
 Animals that hibernate prepare for this phase by building up
a thick body fat layer during late summer and autumn that will
provide them with energy when they hibernate in winter.
 There are two types of hibernation:
 obligate hibernation
 and facultative hibernation.

5. obligate hibernation
 Obligate hibernators can sleep
regardless of access to food and
ambient temperatures.
 Obligate hibernators include
European hedgehogs, mouse
lemurs, various ground squirrel
species, and butterflies among
others.
 While hibernating, ground
squirrels enter a state
called torpor. Their metabolism
drops to as low as just 1% of
summer levels and their body
temperature can plummet to
close to freezing.
 Torpor greatly reduces how much
energy the animal needs to stay
alive until springtime.
Hibernating ground squirrel
Active ground squirrel

6. facultative hibernation.
 Facultative hibernators
hibernate when it’s too
cold and food supply
has reduced.
 Facultative hibernators
include the black-tailed
prairie dogs.
 Black-tailed prairie
dogs go into torpor for
a few days at a time,
and only hibernate on
rare occasions during
extreme cold weather
conditions.

7. Brumation
 Brumation is a state of dormancy in a reptile that
resembles hibernation.
 Reptiles undergo brumation during the late stages of
autumn, and they can wake up only to drink water and
then go back to sleep.
 Reptiles consume a lot of food right before brumation
since they can go for months without eating.
 The brumation phase can last for about eight months
depending on the health, age, and size of the reptile.
Brumation is usually triggered by decreased daylight
hours and cold in winter.
 Reptiles don’t brumate fully in the first year of their
lives; instead they eat less and slow down.

9. Diapause
 Diapause is a phase of delayed development that is
marked by lower metabolic activity in response to
recurring periods of severe environmental conditions.
 It is a predictive tactic which is determined by the
animal’s genotype.
 Diapause is observed in all the life stages of
arthropods like insects, but it’s quite common during
the immobile stages like eggs and pupae.
 About 130 species of mammals and various
oviparous fish species experience embryonic
diapauses.
 Embryonic diapause is characterized by delayed
attachment of embryos to the uterus lining resulting in
the young ones being born in spring.

10. Aestivation
 Aestivation is a form of dormancy which is quite similar to
hibernation, and it’s characterized by reduced metabolic rate
and inactivity in response to arid conditions and high
temperatures.
 Vertebrates and invertebrates can enter into the state of
aestivation to avoid desiccation.
 Animals which aestivate look like they are in a lighter state of
dormancy since they can reverse their physiological state
rapidly and return to normal.
 The main concern of aestivating organisms is retaining water
and conserving energy, ration the use of conserved energy
while stabilizing their body organs and cells.


11. Examples of animals that
undergo aestivation
 Lungfish (Protopterus
sp)
 Waterholding frogs
(e.g. Cyclorana sp and
Neobatracus sp,
 spade foot toads
(Scaphiopus sp)
 Salamnder, and
 several species of land
snails (e.g. Helix sp).

12. Aestivation
 Aestivation is typically defined as a summer or
dry season dormancy.
 The word derives from the Latin for summer
(aestas) or heat (aestus).
 Arid conditions that restrict water and food
availability are the common trigger for
aestivation, often but not always accompanied
by hot summer temperatures.

13.  A form of ‘light’ dormancy involving no
physiological changes that cannot be very rapidly
reversed.
 Arousal in O. lacteal can occur within 10 min
when aestivating snails are sprayed with water, as
assessed both by enzymatic changes and
emergence of the foot from the shell
 Gut tissue may regress during aestivation
(e.g. Cyclorana alboguttata showed reduced mass
and absorptive surface area of the small intestine)
 But skeletal muscle largely resists disuse atrophy
and maintains its contractile capacity.

14.  Strong metabolic rate depression during
aestivation minimizes energy use to prolong total
survival time, but this also means that the normal
turnover of macromolecules (synthesis and
degradation) is much reduced so that preservation
strategies are needed to extend their functional
lifespans.
 This is provided by mechanisms including
enhanced antioxidant defenses and elevated
chaperone proteins, strategies that are well-
known components of the stress response but are
also widely used across all forms of natural
hypometabolism to support viability and life
extension

15. What trigger eastivation?
 Spurred on by ‘selfish genes’, all organisms are driven
to grow, develop and reproduce.
 The primary inputs needed for this are water (the
solvent of life), nutrients (both building blocks for
biosynthesis and fuels for energy production) and
energy (mainly ATP and reducing equivalents, mostly
derived from oxygen-based respiration in animals).
 When one or more of these primary inputs for life is
restricted or unavailable, organisms need a self-
preservation strategy to help them avoid death.
 This frequently involves a strong suppression of
metabolic rate and transition into a hypometabolic
state

16. Physiological and biochemical
adaptations
Mechanisms to
 conserve energy,
 retain body water,
 ration use of stored
fuels,
 deal with nitrogenous
end products,
 and stabilize organs,
cells and
macromolecules of
over many weeks or
months of dormancy.

17. Diapause
 a period of suspended or arrested
development and physiological
activities are diminished in an insect,
other invertebrate, or mammal embryo,
especially during unfavourable
environmental conditions.
 Considered to be a physiological state
of dormancy
 Diapause is facultative and occurs only
when induced by certain adverse
environmental conditions.
 Insect diapause is usually triggered by
environmental cues, like changes in
daylight, temperature, or food
availability.
 Diapause may occur in any life cycle
stage—embryonic, larval, pupal, or
adult—depending on the insect
species.
 The first rains bring ants, mosquitoes
and bugs out of diapause.

18. Diapause in mammals
 Embryonic diapause (ED) is a temporary
arrest of embryo development and is
characterized by delayed implantation in the
uterus.
 ED occurs in blastocysts of less than 2% of
mammalian species, including the mouse
(Mus musculus).

19.  First observed in the
roe deer by observant
hunters. They
observed that there
was a mystery in the
roe deer between
observations of the
timing of mating and
the time of birth, as
the pregnancy
seemed to continue
for far longer than
expected

21. Control of embryonic diapause

22. Cryptobiosis
 A physiological state
in which metabolic
activity is reduced to
an undetectable
level without
disappearing
altogether. It is
known in certain
plant and animal
groups adapted to
survive periods of
extremely dry
conditions.