Chapter 4: Adaptations to Variable Environments Flashcards
Genotype
genetic code for traits
3 types of genotypes
- homozygous dominant (BB)
- homozygous recessive (bb)
- heterozygous (Bb)
Phenotype
physical expression of trait
Gene
portion of DNA that codes for a trait
Allele
diff forms of same trait
Phenotypic plasticity
ability of 1 genotype to produce many phenotypes (depending on environment)
- as envir. changes, phenotypes can change
Bet hedging
giving up immediate, potential gain for hedge against total failure (to lower risks)
examples of bet hedging
- Diversification of timing of egg hatching and seed germination
- Diversified offspring physiology
- Females mating with multiple fathers
- Long life with a little reproduction every year
- Delayed germination of winter annual plants
Phenotypes of Grey Treefrog embyros:
Female frogs- lay eggs days before ready to hatch to avoid predation
- Embryos can sense predators’ chemicals; hatch sooner (survive, but vulnerable)
- When tadpoles sense predators, grow large red tail (can be eaten/lost and regrown
Temporal environmental variation
how environmental conditions change over time
- depends on the severity and frequency
Weather
variation in temp and precipitation over hours–>days
Climate
atmospheric background conditions occur throughout year–>years
Spatial environmental variation
Adaptation based on environment; changes occurs from place-to-place bc of climate, topography, and soil variation
- ex: soil types, dispersion of seeds
- A moving individual perceives spatial variation as temporal (series of events)
- Faster you move, more conditions you encounter
Phenotypic trade-off
neither phenotype does well in both environments
Acclimation
environmentally induced change in individual’s physiology
- most rapid responses (reversible)
- Behavioral, anatomical, and morphological
Enemies:
predators, herbivores, parasites, pathogens
Hermaphrodite
individual w/ male and female gametes
Self-fertilization
can reproduce w/ mate or alone
Inbreeding depression
decrease fitness caused by mating b/w close relatives
Variation due to biotic conditions:
enemies, competitors, mates
Variation due to abiotic conditions:
temperature, water availability, salinity, oxygen
Microhabitat
specific location w/in habitat that differs in environmental conditions
Water availability adaptations: Plants phenotypic plasticity
favors plants that can:
- Close/Open stomata
- Stop/Start transpiration
- Wide/long! root growth (alter root-shoot ratio)
Migration
2 seasonal mvmts of animals
Dormancy
condition in which organisms dramatically reduce their metabolic processes
4 types of dormancy:
diapause, hibernation, torpor, aestivation
Diapause
type of dormancy in insects w/ unfavorable conditions
- Insects
Hibernation
long term- dormancy in mammals; individuals reduce their energy costs by lowering heart rate and decreasing body temp
- Squirrels, bats, bears, etc.
Torpor
short-term dormancy; individuals reduce activity and body temps
- Birds and mammals
Aestivation
shutting down metabolic processes during summer bc of hot/dry conditions
- Snails, desert tortoises, and crocodiles
Optimal foraging theory
model describes foraging behavior that provides best balance b/w costs and benefits of diff foraging strategies
- why animals choose what they eat
- how animals adapt to not be eaten or to eat
4 responses to food variation in space and time:
central place foraging, risk-sensitive foraging, optimal diet composition, diet mixing
central place foraging
acquired food is brought to central place
- parents find, bring back to babies
- try to decrease distance/time, energy costs, and exposure (costs/benefits)
risk-sensitive foraging
influenced by presence of predators
optimal diet composition
range of foods w/ low handling time (amnt of energy gained vs time) and depending on environmental availability
- handling time- amnt of time predator takes to consume captured prey
diet mixing
handling time
amnt of time predator takes to consume captured prey
fitness
ability to put more genes into a population (reproduction)
reaction norm
amnt of time for a species to change
polyphenism
more extreme plasticity; environ. dictates phenotype
sound sensitivity is greatest when…
the distance b/w ears matches wavelength
Phenotypic plasticity in animals:
can show or hide melanin
Phenotypic plasticity in plants:
can produce diff colors based on pH of soil
Phenotypic plasticity in bacteria:
can turn on or turn off genes
Environmental conditions for phenotypic plasticity:
temp, food supply, gravity, light, presence of predators
examples of bet hedging
Diversification of timing of egg hatching and seed germination, Diversified offspring physiology, Females mating with multiple fathers, Long life with a little reproduction every year, Delayed germination of winter annual plants
adaptations for prey (enemy situation)
Prey alter behavior and growth in response to predators
- Improve fitness
Temperature adaptations in fish:
Isozymes form phenotypic plasticity
- Ex: goldfish swim faster at low temps, can survive high but swim slower
adaptations to prevent freezing: fish, insects, amphibians
- fish: glycerol proteins as “antifreeze”
- insects: use bark as insulation
- amphibians: burry themselves in soil, antifreeze chemicals form ice crystals to avoid tissue damage, animals “thaw” in spring
Why animals choose what they eat?
o Lowest risk value
o lowest expendable energy
o Highest nutrients
How do animals adapt to not be eaten or to eat?
o Camouflage, slippery shells, etc.
o Speed, heightened senses, etc.
examples of predictable temporal environmental variation
day/night, seasonal changes in temp and precipitation
examples of not predictable temporal environmental variation
weather and climate
examples of temporal environmental variation heavily impacting ecosystems
- droughts, fires, tornadoes, tsunamis (rare frequency)
- slowly: warming climate
nonplastic genotypes vs. plastic genotypes
- nonplastic: have high or low fitness in varying environments
- plastic: have high fitness in both environments (trade-off)
traits possible for phenotypic tradeoff
behavior, growth, development, and reproduction
what do phenotypically plastic traits respond to?
- environmental cues (smells, sights, sounds, and changes in abiotic condition, and competition)
- some respond at diff rates
what phenotypically plastic traits are rapid? which are irreversible?
- rapid: behavioral
- irreversible: morphology and physiology
“Ciliates in the genus Euplotes” adaptations to predators:
sense chemical signals from predators, within hours grow huge wings to make them too big for a predator to eat
- takes times to develop, so usually small
animals response to food competition
spend more time looking for food or extract more nutrients from food
Burmese python food adaptations
increases surface area of digestive tract to break it down quicker and increases blood flow to extract more nutrients
temperature adaptations of lizards
move in/out of shade and on/under rocks
responses to changes in salinity in aquatic environments
synthesize large quantities of certain amino acids to increase the osmotic potential of the body fluids to match that of the environment
(w/o consequences of salt and urea); TO minimize the cost of osmoregulation
- to return: metabolize excess free amino acids to reduce their osmotic difference
adaptations to lack of oxygen (high altitudes)
increase in red blood cells and hemoglobin to improve oxygen uptake
why do locusts migrate?
eat all of food supply; mass migrations cause destruction to crops
phenotypically plastic response to very extreme changes in environment
migration, food storage, and dormancy
risk-sensitive foraging
altering foraging patterns to avoid predation
3 strategies for bet hedging
- conservative bet-hedging (play it safe, low risk, less variance)
- diversified bet-hedging (don’t pull all eggs in 1 basket, less variance)
- several strategies at once (random from fixed distribution based on predictions)
