Lecture 28. Life in Extreme Environments: Evolutionary Adaptations Flashcards
What are the challenges for organisms abandoning life under water ?
- Desiccation of the body tissues, requiring some sort of waterproof coating
- Respiration of gaseous oxygen rather than oxygen dissolved in water
- Mechanical support (air is not as buoyant as water)
- Transport water and nutrients about plant
- Reduce need for water for reproduction
What are the abiotic factors that affect the distribution of organisms ?
- Temperature
- Water
- Sunlight
- Wind
- Rocks and soil
- Periodic disturbances
What are the two factors that plants require strategies for ?
- Stress
2. Disturbance
What are some things that may prevent stress to plants ?
Light, water, nutrients, temperature
What is disturbance ?
Partial or total destruction of plants
What are some examples of disturbance ?
- Herbivory
- Wind
- Frost
- Fire
What does low stress and low disturbance result in ?
Competitors
What does high stress and low disturbance result in ?
Stress tolerators
What does low stress and high disturbance result in ?
Ruderals
What does high stress and high disturbance result in ?
Not viable
How may plants handle stress in tropical and temperate biomes ?
Avoid or tolerate
How may plants avoid the stress of lack of rainfall ?
Seeds dont germinate unless rain falls
How may a seed adapt to stress ?
- Ability of seed to sense environmental conditions
2. Sufficient resources and time to produce more seeds
How may animals avoid stress ?
- Physiological ability to slow down metabolic rate
2. Pre-hibernation food sources
How do plants in deserts tolerate stress ?
Stomata close during the day to prevent water loss and open at night
What is the function of the ANR gene ?
Required to tolerate extreme dehydration in mosses
How can some plants tolerate the disturbance of forest fires ?
Seeds can only germinate after being burnt
What are serotinous seeds ?
Can only germinate after being burnt
What are the stresses of mangrooves ?
Salinity and oxygen
How do mangroves help decrease the effect of tsunamis ?
Dissipate wave energy
What are the two native angiosperms species found in antarctic region ?
- Deschampsia antartica - Antarctic hair grass
2. Colobanthus quitensis - Antarctic pearlwort
What dominates Antarctic vegetation ?
- Mosses
2. Lichens
What is the largest purely terrestrial animal species on Antarctica ?
Belgica antarticca - Antartic midge
Give some characteristics of the Antartic midge ?
- Flightless
- 2-6mm long
- Can survive having its bodily fluids frozen
- Dark coloured to absorb heat
- Can survive 35% dehydration
- Spends 2 years as larva and 10 days as an adult
- Clumps together to avoid heat and moisture loss
What do upwellings of deep water at the Antarctic convergence bring with them ?
Nutrients
What two factors mean there is an abundance of phytoplankton ?
- Lots of nutrients
2. 24 hours in the summer
What feeds of phytoplankton ?
Antarctic krill
What is an Antarctic ocean not ?
An extreme environment
What are the four levels of the sea ?
- Epipelagic zone
- Mesopelagic zone
- Bathypelagic zone
- Abyssopelagic zone
What depth is the epipelagic zone ?
0-200m (normal sea creatures)
What depth is the mesopelagic zone ?
200-1000m
What depth is the bathypelagic zone ?
1000-4000m (specialised sea creatures)
What depth is the abyssopelagic zone ?
4000m + deep sea trenches
What are the problems of deep sea survival ?
- Extreme pressure
- Darkness
- Extreme cold
How do blobfish (Psychrolutes marcidus) survive under pressure ?
- Small and gelatinous
- Reduced skeleton
- No swim bladder or other air spaces
4.
How doe sperm whales (Physeter catodon) survive extreme pressure ?
Ribs are bound by loose, bendable cartilage which allows the rib age to collapse under high pressure
How do sea creatures avoid darkness ?
Bioluminescence
