Ecology Exam 2

What are adaptations?

variations of phenotypes. helps an organism gain more fitness in its environment

3 requirements of natural selection

heritability

variation

fitness (survival and reproductive responses)

range of tolerance

range at which an organism can optimally exist

• heat is a big stressor for most animals

Thermal Properties of water

high heat capacity (how many calories it takes to raise water temperature by 1° C

• note: C = Kcal and c = calories; we are using little c

absorbs more than air

resists phase and temperature changes

Density

water is very dense

800x denser than air

lipids and fats are less dense (why we float)

bones and proteins are denser than water

What are the properties of water?

• High heat capacity (limits thermoregulation)

Adaptations

• density

• viscosity

• solvent capacity

• osmotic potential

viscosity

resistance of movement (drag)

• reduces or increases drag

Solvent Capacity

water has a medium movement capacity (movement and reactivity)

can transport important elements and nutrients/micronutrients

• all soluble in water

• salt calcium and hydrogen

• H⁺ ion is reactive (pH)

Osmotic Potential

Force of attraction between water and aqueous solutions

• units of pressure MPa

• passive transport is semipermeable membrane

Adaptation for Density

swim bladder (fish and kelp)

algae use oil droplets to stay afloat

adaptations for viscosity

streamlined body shape (like a dolphin)

zooplankton want to float, so they have appendages to use viscosity in a different way

Solvent Capacity and Osmotic Potential adaptations

passive and active transport allows water to go through semipermeable membrane

Hyperosmotic vs hypoosmotic vs isotonic

affects nitrogen balance

Passive transport

molecules move along concentration gradient; moves from many solutes to few solutes

• osmosis

• diffusion 

• facilitated transport

Active Transport

cells transport molecules against gradient to maintain concentration

Note: expends more energy because cells work against gradient 

• Vesicles -endocytosis and exocytosis

• Protein pumps

Isotonic cells

Water flows from cells and surroundings equally

hyperosmotic cells

water flows out of cells and cell shrinks

hypoosmotic

water flows into cell and cell grows

Are Freshwater fish hyper- or hypo- osmotic? What does that mean?

Freshwater fish are hyperosmotic, meaning they have a higher concentration of solutes in their body than in their surrounding water.

How do freshwater fish take in water? What happens to most of the water they take in?

They take in water through their food and osmosis in their mouth and gills. Water passes through their body and kidneys filter out excess water causing a lot of urination.

How do freshwater fish take in solutes? What happens to most of the solutes they take in?

Solutes are taken in through the food they eat and active uptake in the gills. Most of the solutes remain in the fish because the kidneys reabsorb it.

Are Saltwater fish hyper- or hypo- osmotic? What does that mean?

Saltwater fish are hypoosmotic meaning organisms have a lower concentration of solutes than their surroundings

How do saltwater fish take in water? What happens to most of the water they take in?

Drink lots of water and retain most of it. Water lost through gills (osmotic loss) and urination. The kidneys conserve most of the water so they only urinate a little. 

How do saltwater fish take in solutes? What happens to most of the solutes they take in?

take in salts through the water that they drink. They excrete most solutes from their kidneys and gills

Salt balance in coral reefs

high temperatures → Ocean evaporation → higher salt concentrations → coral bleaching

salt balance adaptations in mangrove trees

high solutes in roots and leaves lead to salt glands in leaves and active transport in roots to remove excess salt

Ammonia (NH₃) in the role of nitrogen balance

byproduct of protein digestion, toxic to tissues

• Excreted easily in aquatic systems

• Dilute urine

Sharks/Rays Nitrogen Balance

Urea (CO(NH₂)₂)

• damages proteins

• Use it to add/subtract solutes from the blood

• Trimethylamine oxide protects proteins

Terrestrial Nitrogen Balance

 Uric Acid (C5H4N4O3)

• little water needed

Urea

• Loop of Henle

Explain Cohesion-Tension Theory

how water moves across gradients

Transpiration:

• osmotic potential draws water in

• root pressure and cohesion draw water up xylem

• Gravity pushes it back down

• Water potential in leaves- evaporation creates tension in leaves

adhesion

water sticks to a surface

cohesion

water molecules stick to other water molecules

What do soils provide?

nutrients and water

matric potential

stickiness of soil particles; how easy is it for plants to pull water from the soil?

• increased volume = increased stickiness

Note: clay soils have highest surface area to volume ratio

Field Capacity

how much water the soil holds before sinking into the water table

Wilting Point

point at which plants can no longer pull up water from the soil

• Note: think about when you are sipping a drink through a straw. when you get to the end you can still see a little in the bottom but you can’t suck it up with the straw.

What do most soils consist of?

Sand, silt and clay

What is the best type of soil? Why?

loamy soils, they have a medium field capacity and wilting point compared to clay and sandy soils

thermal optimum

indicates the temperature at which organisms have their best performance

• between 0 -100°C

• <45°C for Eukaryotes

What are some pros of heat?

Kinetic energy

movement of molecules

speeds up chemical reactions

What are some cons of heat?

denatures proteins and destabilizes protein structures

lose structure

malfuctions

homeotherm

maintain constant temperature internally

poikilotherm

relies on ambient temperatures (body temperature varies)

heterotherms

body temperatures differ between both internal and ambient temperatures

Ectotherm

body temperature determined by surrounding temperatures

Endotherms

generate metabolic heat to raise body temperatures (internal)

Heat Budget

what energy is required to perform typical behaviors (growth, reproduction etc.)

Thermal Inertia

The resistance to a change in temperature due to a large body volume.

surface area to volume ratio

• smaller animals have a higher ratio meaning they are going to lose or gain heat faster than a larger animal

• the smaller the animal, the larger the ratio

What are the 4 sources of heat?

Radiation, Conduction, Convection, Evaporation (and Respiration)

Radiation

Infared

sun, sky, land, surfaces

reradiation occurs from air and landscape

conduction

direct contact

Based on:

• SA:V

• ambient vs. internal temperature

• resistant to heat transfer

  • water has low resistance

  • heat loss in water 20x faster than in air

Convection

transfer by movement

gain energy and move away

disrupts boundary layer (spines, hair etc.)

Evaporation

gas exchange and surface

rise of water loss

rate doubles with each 10°C increase (dry only)

• relative humidity (humidity sucks)

What are some ways organisms cope with the cold?

Homeostasis: keep body temperature above freezing

biomechanical responses

biochemical responses

anatomical responses

behavioral responses

Muscle Heat

red muscle in fish

muscle contractions to create heat

countercurrent heat exchange

Movement of two fluids in opposite directions on either side of a barrier through which heat or dissolved substances are exchanged.

blood shunting

allows specific blood vessels to shut off so that less of an animal’s warm blood flows to the cold extremities.

antifreeze molecules

glycerol is used to lower the temperature at which the cells freeze

glycoproteins coat hydrogen ions to prevent ice layers from forming

Ex. Antarctic fish and terrestrial invertebrates

What do plants do to resist freezing?

move water out of cells; grow lower to the ground and closer together to conserve heat (tundra)

Photosynthesis

6C02 + 6H20 + proteins → C6H12O6 + 6O2

Light Reactions

• C3 Photosynthesis

• C4 Photosynthesis

• CAM

C3 Photosynthesis

CO2 + RuBP → 2G3P

Occurs in the Mesophyll

• 2G3P enters the Calvin Cycle

• self-limiting CO2 intake from environment

CO2 comes from opening stomates

• allows for gas exchange; causes water loss

• not good for plants in hot, dry, climates

C4 Photosynthesis

CO2 + PEP → OAA

Occurs in the mesophyll

PEP grabs to CO2 better; don’t have to leave stomates open

CAM Photosynthesis

“Crassulacean Acid Metabolism”

Calvin Cycle at night (stomates bring in CO2 at night when it’s cooler)

• pushes CO2 into bundle sheath and perform photosynthesis during the day

What are some anatomical adaptations of plants to cope with temperature?

• increase edge to surface area on leaves 

• no leaves at all

• waxy cuticles

• recess stomates

Note: the goal is to increase boundary layer to avoid evaporation

What are some anatomical adaptations of animals to cope with temperature?

• Anatomical structures (heat shields and large ears

• Boundary Layer (puffing of feathers, fur, etc.)

• Kidney size and function

Adaptation vs. Acclimation: Adaptation

evolutionary process

better suited for their environment (increased fitness)

Acclimation

doesn’t drive evolution

often reversible

response to environmental variation

can happen quickly

can be spatial or temporal

temporal variation

fire, disease, etc.

temporal vs spatial variations

climate vs weather

Spatial Variation

climate, topography, soil

Spatial - temporal Correlation

Phenotypic Plasticity

The ability of a single genotype to produce multiple phenotypes

• Inducible

• (Ir)reversible

• Fast/slow

Types:

• physio

• morpho

• behavioral

• life history

Non-plastic phenotype

phenotype that is only good for one environment. Does not change when the environment changes

plastic phenotype

a phenotype that can be helpful in many environmental conditions. It lowers fitness in both however some fitness is better than no fitness

Coping with the environment

Look at notes and slide show

microhabitats

an area within a habitat that has a slight change in temperature. Often allowing for an animal to move there as a coping strategy for the heat or cold

What are the types of dormancy?

aestivation, hibernation, torpor, diapause

diapause

insects: used whenever there are unfavorable conditions

hibernation

endotherms: store body fat, lower heart rate and body temperature

aestivation

similar to hibernation but in hot, dry climates

torpor

short periods of time; body temperature drops

What is the goal of optimal foraging?

minimize expenditures and optimize benefits

What are the types of optimal foraging?

central place foraging

risk-sensitive foraging

optimal diet composition

diet mixing

Central place foraging

graphs predict optimal amount of time to travel to get more food

greater risk of predators and energy expenditure the farther away you go

• cost/benefit analysis

• law of diminishing returns

risk sensitive foraging

based on the variability and risk associated with food sources, balancing energy gain against potential dangers

small and large chub experiment

optimal diet composition

energy expenditure/handling time are considered

Things to consider:

• energy output from food

• handling time

• encounter rate

always eat highest energy food item if abundant; only eat lower energy items if high energy items are scarce

diet mixing

mixing foods together to get more nutrients

How do organisms know they need to make adaptations?

timing of physiological and behavioral change

assess the environment

assess individual needs

What does an organism’s ability to assess the environment include?

food supplies

predation risk

indirect environmental cues (photoperiod)

What does an organism’s ability to assess individual needs include?

growth, reproduction, senescence

metamorphosis, dormancy

behavior

climate change (makes these more difficult)