Ecology Chapter 4- Coping with Environmental Variation

adaptation could allow later generations of a pop to return to pre-stress level

-individuals w a trait that better enables them to tolerate stress are more likely to survive and have higher reproductive rate -after generation this trait could become ubiquitous in the population (ex adaptation)

Temperature affects physiological activity

1) Rate of occurrence of chemical reactions- directly or indirectly; chemical reactions require enzymes which are most efficient in specific temp range 2) cell membranes- lose function at low temps; leak and transport proteins lose function - temp at which this occurs depends on lipids in membrane 3)water loss increases as temp increases

3 options for physiological stress

1) avoidance 2)tolerance 3)die

4 heat transfer mechanisms

1) conduction= transfer of heat via direct contact of molecules 2) convection= conduction + fluid/gas flow 3) latent heat transfer= heat loss from evaporation or evapotranspiration (liquid to gas) 4) radiant heat transfer=movement of heat via electromagnetic waves (solar-thermal)

Amphibians avoid H2O loss across think skin by

1) living in moist environment 2) increasing skin thickness-reduces O2 intake so breathes faster to compensate 3) some frogs have highly vascularized and or bumpy ventral skin to increase H2O absorption 4) thick and bumpy dorsal skin in terrestrial frogs (toads) reduces convective water loss

Avoidance of water loss in reptiles

1) shredding increases thickness of all skin layers, especially outermost one of keratin 2) scales provide protection and reduce H2O loss 3) snake urine is a dry solid 4) unlike amphibians, reptile eggs can be in dry locations since they have leathery/hard shell resistant to drying and storage area for wastes example: kangaroo rates

hibernation vs aestivation

Hibernation or "winter sleep" is the state of inactivity or low metabolic process performed by the animals during winters. Aestivation or "summer sleep", on the other hand, is the low metabolic process by the animals during summers.

Acclimatization changes the ___ response by altering the lower or upper critical temps resulting in ______

acute, less energy consumption

Populations respond to abiotic variation via____

adaptation- genetic change in entire population includes ability to acclimatize which reduces but does NOT eliminate physiological stress

Mycorrhizal fungi

affect h2O balance in plants symbiotic fungi attached to plant roots help plants by increasing H2O absorption due to large surface areas plants help fungi by donating food (fungi inserts filaments into root cells)

Acclimatization and special adaptations affect H2O balance

allows plants from dry environments to survive 1) shed leaves in dry periods reduces evaporation water loss and less tissue to maintain 2) adjust root biomass to optimize H2O so allocate< energy to leaf/stem growth, dry plants adjust ratio of root/shoot 3) Thicker cuticles (permanent or seasonal) reduce water loss 4)Plants from dry areas have better stomatal control to more efficiently balance H20/)2needs

Osmoregulation

balance of uptake and loss of water and solutes to regulate body fluid composition and pH affected by changes in external environment

Avoidance

behavioral response ex: basking in sun seek shelter adjust activity times to conserve water or stay cool

Bergmann's Rule

body mas increases w latitude and colder climate -large northern deer retain heat better bc low ratio but small southern deer can lose heat faster

Rate of ____ depends on rate of air movement

convective heat loss boundary layer= nonmoving air around a leaf thicker BL= decreased air movement and decreased convective heat loss -several leaf morphological characteristics affect its boundary layer thickness thereby determining its rate of heat loss or gain via convection 1) size- small leaves=decreased boundary layer = increased heat loss 2) shape- flat leaves= decreased boundary layer = increased heat loss 3)texture-smooth=decreased boundary layer and increased heat loss leaves toward wind=more heat loss leaves away from wind=less heat lostt

Surface area to volume ratio

determines rate of heat and water gain/loss small animals have higher ratios and more prone to H2O loss and rapid shifts in temperature affected by body shape, size, appendages when comparing 2 animals of similar volume, elongated animals have increased SA exposed than compact and higher ratio elongated limbs and other appendages can increase SA lower SA/V ratio makes large ecotherms improbable (dinosaurs)

ectotherms

ectotherms can augment costs behaviorally or via morpho changes; can keep animal warm w/o energy; basking, dark during day to absorb more heat, light at night to reduce heat loss activity limited when cold need many enzymes and physiological adaptations to function at varying temps (requiring energy to produce)

Allen's Rule

endotherms from colder climates usually have shorter appendages and lose heat rapidly

Temperature of an organism is determined by

exchanges (+/-) of energy with the external environment

The higher surface area to volume ratio, the _____ the heat loss

faster

Lower Critical temperature of animals varies...

geographically, seasonally, and among species based on their energy demands and food availability -LCT determines endotherms energy use -the lower the LCT the wider the thermoneutral zone(TZ) and thus less energy is used -animals w higher energy demands or less access to food must have a low LCT to conserve energy

Energy used for acclimatization is energy not available for _____

growth, survival, reproduction -population in constant environments don't need to acclimate -ability and level of phenotypic plasticity an organism gas reflects ranges of conditions experiences in natural environment -can demonstrate using reciprocal; transplant experiment ex: NJ w decrease food and seasonal variation has decrease need for acclimatization

Natural selection acts on ____ resulting in populations and adaptations that reduce physiological stress

individual phenotypes

Transpiration can be used to _____ temp

lower not good in dry areas bc some plants shed leaves to avoid water stress so need to use other methods to control body temp

endotherms

lower and upper critical temps can determine how much energy it needs

Water and Salt balance in fresh and saltwater fishes

passive movements of water (osmosis) cause imbalance drinking, eating, excretion and active transport compensate for gains/losses example: figure 4.24 ****Picture

Acclimatization limited by _____

phenotypic plasticity=range of phenotypes that can be displayed by a genotype in response to environmental variation -range varies between species, populations, and individuals -increased plasticity=increase ability to tolerate environmental variability the process of the body temporarily adjusting to the environment

Geographic ranges of species are constrained by ___ and _____ factors

physical (abiotic) and biological (biotic)

Plants also gain and loose heat in similar ways to animals

plants lose or gain heat at varying rates depending on morphological and physiological attributes that affect 1) rates of transpirations 2)rate of convection 3)reflective abilities

Range of tolerances to varying abiotic factors influences....

potential distribution and abundance but actual distributions may be narrower than potential ones due to additionally abiotic and biotic constraints: !0 extreme climatic conditions 2) disturbance 3) species interactions- interspecific competition, predation, etc

Torpor

reduced state of activity and metabolic rate may occur over short or long periods of time 1) daily torpor occurs in many bats, small mammals, birds 2) long term torpor is hibernation=response to cold and food scarcity (black grizzly bears have many metabolic changes that let them hibernate up to 7 1/2 months without eating, drinking, urinating, defecating) (graph) or long term can be Aestivation=response to heat/H2O scarcity=lower metabolic rate and burry in mud in hot places ex: frozen frogs

Leaf ___ affect the rate of radiant and latent heat transfer

reflective properties pubescence's- increases reflected sunlight helping to lower heat gain due to radiant heat transfer; also has loss of solar radiation for photosynthesis and less effective convective cooling and thus should have less pubescence in climates or seasons that are wet or have less sunlight

Limited range of abiotic conditions under which an organism can survive and reproduce

suboptimal conditions result in suboptimal physiological performance (physiological stress) and thus reduced survival, growth, reproduction

Heat gains and losses can be summed to determine overall temperature change

temp change depend on 6 factors

H2O balance affected by adaptations that determine the rate of ____

transpiration

Morphological and physiological attributes affect the rate of ____ and thus heat loss via ______

transpiration, evaporation 1) # of stomata- determined by size and # of leaves stomata size and density 2) degree of stomatal opening-determined by hormones in h20 stressed plants 3) cuticle thickness 4) orientation 5) leaf closure

Tolerance

typically occurs via morphological or physiological adaptations morphology- dense fur, dark skin, thick fat morph-live in desert w/o drinking bc most h2o returns to circulation bc of extra long loops of henle to kidney and high adh acts on collecting ducts and little urine (kangaroo rat)