L7 Developmental adaptations Flashcards
what 2 options do insects have to cope with unfavourable conditions
migrate or enter a dormant state
what does the photoperiod predict
future seasonal conditions
how is the photoperiod detected
brain or photoreceptors in eyes
give an example of an insect which migrates
monarch butterfly
what is the furthest recorded insect migration
18,000 km by plantana flavescens (dragonfly)
what is the photoperiod
day length
what is involved in pre migratory behaviour
redirecting metabolism to energy storage instead of reproduction
how many insects migrate across the South of the UK every year
~ 3.5 trillion
in which climate are periods of dormancy most likely to occur
temperate
what is the name for dormancy occurring in summer
aestivation
what is the name for dormancy occurring in winter
hibernation
what are the 2 types of halted development
quiescence and diapause
what is quiescence
halted/slowed development as a direct response to unfavourable conditions
what is diapause
arrested development and adaptive physiological changes, normal development continues with physiological stimuli
which of quiescence and diapause are internally monitored
diapause
what is a disadvantage to diapause
responds to physiological cues rather than environmental stimuli so conditions might not always be favourable when emerging
what is voltinism
the number of generations per year
what is the name for having 1 generation per year
univoltine
what is the name for having 2 generations per year
bivoltine
what is the name for having more than 2 generations per year
multi / polyvoltine
what is the name for having less than 1 generation per year
semivoltine
which regions are more likely to have semivoltine insects
colder temperatures or nutritionally poor conditions
give an example of a semivoltine insect
period cicadas
broad-bpdied chaser dragonfly
what is the name for diapuase which occurs regardless of environmental cues and which insect is it likely to occur in (in terms of generations/year)
obligatory diapause (genetically programmed)
univoltine (one generation per year)
what is facultative diapause
diapause which is optional
when might facultative diapause occur
survival of unfavourable conditions like food shortage
which insects show facultative diapause (in terms of gen/yr)
bivoltine or multivoltine
how long can diapause last
days, months, sometimes years
when in insect lifecycle is diapause most likely and why
egg or pupal
conveniently packaged in protective layer
when might reproductive diapause occur
when metabolism must be directed towards surviving environmental stress (migration, production of cryoproducts)
what does phenology mean
timing or seasonality
what is the negative implication of climate change on diapause
photoperiod is unchanged but temperature is elevated
longer growing season creates asynchrony between plants and insects
what are the 2 main environmental extremes influencing insects
temperature and humidity
what effect does extreme cold have on insects
cause desiccation - freezing body fluids
how can insects survive extreme cold
cryoprotection
what is supercooling
when liquid is cooled to a temperature below it’s freezing point but does not freeze
what is a supercooling point
the lowest temperature an insect can be cooled before spontaneous ice nucleation occurs in body fluid
how is ice formed
impurities in water act as nucleating points forming ice crystals
what is the most common adaptation to cold
freeze avoidance (defences)
where is freeze intolerance common
N hemisphere, temperate areas
cold seasonal but can last long
what do freeze intolerant insects do to prepare for cold
lower supercooling point by producing anti-freezes and heat shock proteins, accumulate cryoprotectant, remove nucleating agents
where is freeze tolerance found
S hemisphere and very cold places where freezing periods are extended
what do freeze tolerant species do to prepare for cold
produce ice-nucleating and heat-shock proteins, accumulate cryoprotectant
why do freeze tolerant insects freeze at higher temps
avoid rapid uncontrolled formation of ice crystals which cause injury
give an example of a freeze tolerant insect
arctic woolly bear moth
which has a higher mortality, freeze tolerance or avoidance
avoidance
what is rapid cold hardening (RCH)
almost instant cold tolerance for brief exposures to non-lethal temperatures before insect is in a cold-hardy state
what threats to extreme heat pose
denaturing proteins and water loss
what behaviour can allow acclimation to warmer temperature
burrowing
what threat does aridity pose
water loss
how can water loss be dealt with in arid conditions
enclosure of spiracles, low Na+ levels (low metabolic rate) secretion of uric acid
what takes up the majority of a stag beetles life time
underground as larva, 3-7 years
