Chapter 8: Adaptations to Variable Environments

what are environments

heterogeneous

how does variation occur

over space and time

what kind of scales does variation occur at

different spatial and temporal scales

what do organisms have

adaptations to deal with environmental variation

phenotype

traits of characteristics of an organism, influenced by genes and environment

fitness

ability of an organism to survive and reproduce

phenotypic plasticity

the ability of a single genotype to produce different phenotypes in different environments

example of phenotypic plasticity

gray tree frog tadpoles can sense predator chemical cues, they produce a phenotype that allows fast escape when predators are present and fast growth when predators are absent

what kinds of traits are plastic

behavior, growth, development, and reproduction

phenotypic tradeoffs

a phenotype experiences higher fitness in one environment and lower fitness in other environments

what can plasticity be beneficial in

variable environments

adaptations to enemies

many species alter their growth, body shape, and behavior in response to the presence of predators

example of adaptation to enemies

daphnia can produce helmets in the presence of predators

adaptations to enemies for plants

plants can response to herbivores via inducible defenses

example of plant adaptations to enemies

virgina pepperwood

adaptations to competition

plants can response to increased density by growing taller

example of plant adaptation to competition

jewelweed

variation in food availability

animals may alter behavior or morphology depending on food availability

example of variation in food availability

after a Burmese python eat it doubles the length of its intestine and increases heart size by 40% and blood flow by 10x

what does self fertilization allow

reproductive assurance but can result in inbreeding depression

what do some species exhibit

delayed selfing

what is an example of competition for mates

the hermaphroditic common pond snail delays egg laying if mates are unavailable, self fertilizing snails lay fewer eggs

adaptations to temperature variation

many organisms can adjust their physiology to maintain activity across different environmental temperatures

microhabitats

many animals respond to temperature by moving microhabitats

example of microhabitat

the desert iguana regulates its body temperature by basking on rocks, seeking shade, or burrowing in the ground

adaptations to water availability

in response to scarce water, many plants will close their stomata or grow longer roots

what do rocky tidal pools have

variable salinity (splashing waves, rain water)

what does copepod tigriopus synthesize

amino acids proline and alanine to balance osmotic potential with increased salt water

what is cost of adaptations to salinity variation

metabolic cost, increased respiration

adaptations to oxygen variation

less oxygen at high elevation

how do animals adjust to oxygen

animals can adjust breathing rate, heart rate, and number of red blood cells

migration

the seasonal movement of animals from one region to another

energy storage

animals accumulate fat or cache food supplied for periods of harsh weather when food is inaccessible

where do plants store nutrients and energy

in roots

dormancy

organisms dramatically reduce their metabolic processes

diapause (shutdown)

partial or complete physiological shutdown in response to unfavorable conditions; common in insects

hibernation (sleepy)

individuals reduce the energetic costs of being active by lowering heart rate and decreasing body temperatures; common in mammals

torpor (drowsy)

a brief period of dormancy in which individuals reduce activity and body temperature; common in birds and animals

aestivation (siesta)

shutting down metabolic processes during he summer in response to hot and dry conditions, examples include snails, desert tortoises, and crocodiles

what can cold response occur at

different intensities

compared to species living in a homogenous environment, a species living in a heterogeneous environment is more likely to

exhibit phenotypic plasticity

an organism that can surviving well in cold temperatures but not in hot temperatures illustrates the concept of

a phenotypic trade off

if self fertilization results in low fitness, why would an organism choose self fertilization as a mating strategy

it ensures reproduction in low population densities

which behavioral is optimal for an organism using central place foraging

increase time spent searching for food at longer distances