Ch 04 - Coping with Environmental Variation: Temperature and Water

Organisms have two options for coping with environmental variation: () and ()

Tolerance and Avoidance

What is an example of coping with environmental variation tolerance and avoidance?

Spruce trees in the boreal forest must be able to tolerate temperatures fro -50 C to 30 C

() -Study of interactions between organisms and their environment and how these interactions influence their survival and persistence

Physiological ecology

Each species has a range of () tolerances that determines its potential () distribution

Environmental

Geographic

The physical environment influences an organism’s () () (survival and reproduction) in two ways

ecological success

what are the two ways the physical environment influences an organism’s ecological success?

1. Availability of energy and resources - impacts growth and development

2. Extreme conditions can exceed tolerance limits and impact survival

() supply can influence an organism’s ability to tolerate environmental extremes

Energy

The actual geographic distribution of a species is also related to other factors such as () (), (), and ()

dispersal ability

disturbances

competition

Because plants do not move, they are () indicators of the () environment

good

physical

What is an example of a response to environmental variation?

Aspen distribution can be predicted based on climate

Limiting factors include low () and (), which affect reproduction and survival

Low temperatures

drought

A species’ () () is the range of conditions over which it occurs

Climate envelope

What is a climate envelope a useful tool for?

Predicting the species’ response to climate change

Stress

Environmental change results in decreased rates of physiological processes, lowering the potential for survival, growth, or reproduction

Deviations from the () reduce the rate of the process

Optimum (environmental factors: temp, nutrients, habitat)

Ex: at high altitudes, lower partial pressure of O2 in the atmosphere results in hypoxia - not enough oxygen is delivered to tissues

Hypoxia causes “altitude sickness,” which is physiological stress

Acclimatization

Adjusting to stress through behavior or physiology

it is a short term, reversible process

Acclimatization to () () involves higher breathing rates, greater production of red blood cells, and higher pulmonary blood pressure

higher elevations

Over time, natural selection can result in () of a population to environmental stress

adaptation

Individuals with traits that enable them to cope with stress are ()

favored

Over time, these () () become more () in the population

genetic traits

frequent

the effect of stress

ok

() - populations with adaptions to unique environments

Ecotypes

Ecotypes can eventually become () species as populations () and become reproductively ()

separate

diverge

isolated

EX: Humans have lived in the Andes Mountains for 10,000 years

• When the Spanish first settled there, their birth rates were low for 2-3 generations due to poor oxygen supply to developing fetuses

• The indigenous Andean populations were adapted to the low-oxygen conditions by having higher red blood cell production and greater lung capacity.

Example of adaptation

• Indigenous Andean populations have high red blood cell concentrations and large lung capacity

• Tibetans have faster breathing rates and higher blood flows

Adaptions can vary among populations

Acclimatization and adaptation require investments of () and () resources, representing possible ()-() with other functions that can also affect survival and reproduction

energy

resources

trade-offs

The () of an organism is determined by exchanges of () with the () ()

temperature

energy

external

environment

Environmental temperatures vary greatly throughout the ()

Biosphere

Some habitats experience little (), while other have () seasonal or daily variation

variation

large

Survival and function of organisms is strongly tied to ()

internal temperature

Some organisms can survive periods of extreme heat or cold by entering a state of (). in which little or no () () occurs

Dormancy

metabolic

activity

What is Dormancy?

Little or no metabolic activity occurs

An organism’s temperature is determined by the () of gains and () of energy to the external environment

Gains

Losses

Organisms must either () temperature change or () it by physiological, morphological, or behavioral means

tolerate

modify

() controls physiological activity

Temperature

Metabolic reactions are catalyzed by (), which have narrow () ranges for optimal function

enzymes

temperature

At () temperatures, enzymes become (), which () enzyme function

high

denatured

destroys

Bacteria in hot springs have enzymes that are stable up to ()

100C

Antarctic fish and crustaceans must have enzymes that function at ()

-2 C

some soil microbes are active at temperatures as low as

-5 C

Temperature also affects () ()

water

availability

The rate at which terrestrial organisms lose water is created to () ()

air

temperature

Some organisms use () to () exchange of () with the the environment

behavior

control

energy

what is an example of variation in temperature?

ex: elephants swim and spray water onto their backs with their trunks to cool their bodies

ex: moving into the shade reduces the amount of solar radiation received

what are the 3 energy exchanges with the environment?

1. conduction

2. convection

3. latent heat transfer

what is conduction?

transfer of energy from warmer to cooler molecules

what is convection?

heat energy is carried by moving water or air

what is heat transfer?

water absorbs heat as it changes from a liquid to as gas state

for terrestrial plants, energy inputs include () and () () from surrounding objects, as well as from () and () if the ground or air is warmer than the plant

sunglight

infrared

radiation

conduction

convection

losses of energy include () of () radiation, () and () convention, and ()

emission

infrared radiation

conduction

convection

evapotranspiration

energy change in terrestrial plants

what is the equation for temperature change in a plant?

Plants can adjust energy () and ()

inputs

outputs

Transpiration rates can be controlled by () () cells surrounding leaf opening called ()

specialized

guard

stomates

Variation in degree of () and number of () controls the rate of () and thus leaf ()

opening

stomates

transpiration

temperature

stomates control leaf temperature by controlling transpiration

if soil () is (), transpirational cooling is () a good mechanism

water

limited

not

() - hears on leaf surfaces that reflect solar energy. But hairs also reduce conductive heat loss

Pubescence

Pubescence was studied in three () species (plants in the daisy family)

Encelia

• desert species with high pubescence were compared with non pubescent species from wetter, cooler habitats

• plants of all three species were grown in both locations

• in the cool, moist location, 3 species showed few differences in leaf temperature and stomatal opening.

• in the desert, the species with no hairs maintained leaf temperature by transpiration or shedding leaves; the pubescent species’ leaves reflected about twice as much solar radiation

the study of 3 Encelia species

• Natural selection has acted on ecotypes of E. farinosa

• in the driver environments, plants have more pubescence and absorb less solar radiation than populations in moister environments

• The desert species (E. farinosa) also has smaller, more pubescent leaves in summer than in winter, representing acclimatization to hot summer temperatures

Sunlight, seasonal changes, and leaf pubescence study of Encelia species

If air temperature is () than () temperature, heat can be lost by ()

lower

leaf

convection

() heat loss is related to the () of air moving across leaf ()

convective

surface

()- a zone of turbulent flow due to friction, next to the leaf surface

Boundary layer

a leaf boundary layer

the boundary layer convective () ()

heat loss

Boundary layer () is related to () () and surface ()

layer

leaf size

roughness

(), smooth leave have () boundary layers and () more () than large or rough leaves

small

thin

lose

heat

in cold, windy environments, convective () loss is a problem for plants

most alpine plants () the ground surface to avoid high wind velocities

some have a layer of () hair to lower convective heat loss

heat

hug

insulating