Homeostasis and Energy

Unit 2

Species are expected to move “____ & ______” in order to stay within their optimal climatic change

“poleward & upward (higher elevation)”

Which would be easier for animals and plants: moving poleward or upward? Why?

Upward; every 100 m of elevation is equivalent to approx. 1 degree of latitude; it’s easier to migrate 100m than 100 km

True or false: the presence of mountains in an ecosystem make it easier for migrating plants and animals to experience more change with less distance?

True

Is migrating upward difficult?

Yes, it is still difficult; it’s just less difficult than migrating poleward

Describe Forest “migration”

• takes much longer

• must happen in stages

Should we let nature take its course when it comes to species migration due to climate change or should we assist them in order to”speed up” the migratory process?

There is no right or wrong answer!

How does climate change affect annual events?

It affects the Phenology of these annual events

What is Phenology

• the timing of seasonal changes in plants and animals

• Ex. flowering, migration, calving, molting, etc. 

• changes in phenology are the result of earlier spring/longer growing periods

Describe Phenological Mismatch

• when the timing of events for interacting species no longer co-occur

• Ex. plants/pollinators: plants flower before insects emerge or vice versa

• Ex. Grazers and food availability: migration and plant growth can become out of sync

If species can’t migrate fast enough, or they have an insurmountable phenological mismatch, what are the options for them?

• adapt/evolve: this is possible, but can be slow & needs a large genetically diverse population

• OR extinction: can be local or global; some kinds of organisms are much more susceptible than others

Describe Homeostasis

• a dynamic equilibrium which is actively regulated to maintain a variable at a constant level (not just temp.)

• acceptable range, rather than a point

Describe regulation through negative feedback

• a system that promotes stability by counteracting a stimulus

• stress or disturbance changes the internal environment 

• change is detected by receptors

• corrective measures are activated

• corrective measures counteract the change back toward set point 

Describe an estuary

• an ecosystem where salt and freshwater mix to form brackish water

What is osmolarity?

• solute concentration; organisms can be osmoconformers or osmoregulators

_____ _______ transforms the energy in organic molecules into ATP and heat (and C gets exhaled as CO2)

Cellular respiration

What do chemical bonds store energy as?

Potential energy; when bonds are broken that energy can be used by the cels

True or false: glucose has more energy? 

True

What are the types of energy?

• chemical

• electrical

• solar (light)

• thermal

What are the laws of thermodynamics that dictate how energy flows through biological systems?

1. energy can never be created nor destroyed; only transformed

2. every energy transfer or transformation increases the entropy (disorder) of the universe

Is all energy released in biological systems useful?

No; only some energy released is useful, most is dissipated or “lost” as heat or waste

About how much energy in the glucose that enters cellular respiration do you think is assimilated?

Around 30-40%; even lower (like around 10%) if you think about the energy that is actually used to repair tissues. There are times when this is good and times when it is bad

______ stops the ATP making step of respiration and just generates heat

Thermogenesis

Are organisms in a food web equally important?

No

Where does the energy in a food web originally come from? 

Sun

What determines whether an organism is a autotroph or a heterotroph?

determined by where the carbon comes from

where does an autotrophs carbon come from? where does a heterotrophs carbon come from?

• Autotrophs = inorganic C (CO2)

• Heterotrophs = organic (C & H); anything alive or that used to be alive

How much energy is retained at each trophic level? 

10%

Autotrophs in the kelp forest ecosystem include:

• kelp

• other kinds of seaweed

What are plankton?

Officially, anything that drifts with the tides and currents (not sessile, often microscopic); technically the MOLA MOLA sunfish is a plankton

What are the characteristics of phytoplankton?

• “plant plankton”

• photosynthetic microorganisms/algae

• not primary producers

• contributes ½ of the world’s O2

What are the characteristics of zooplankton? 

• usually just small invertebrates

• eat phytoplankton or other zooplankton

What is one species that is a primary consumer and a secondary consumer?

Large crabs

What is the Otter Energy Budget?

How otters spend energy and where they get it from

What do sea otters spend the majority of their time doing?

• low energy activities like resting and feeding

• they have different activities and therefore need to budget for that

How do you calculate how much of one organism an otter needs to consume in order to meet their caloric needs? 

Take the calories provided and divide them by the number of calories an otter would need from that specific food item 

How much energy does it take to get/eat the prey item?

• how long it takes to find

• how many there are

• how deep they have to dive for it

• how hard it is to open/eat

• how dangerous it is (different kind of cost)

• ULTIMATELY: ENERGY GAINED - ENERGY LOST

What determines the best foraging strategy?

Energy expended during dives

Predators use foraging strategies that maximize what?

energy gain (optimal foraging theory)

What does the optimal foraging theory state? 

predators choose the prey that maximize NET energy (energy gain - energy spent) 

Describe prey switching

predators switch to the next best prey item when a preferred item becomes rare (energetically more costly to obtain).

Initially, sea otters used to eat a lot of _____ until they became rare. After this, the otter population dropped and they switched to consuming clam and kelp crab primarily.

urchins

What is the order of otters’ preferred prey items that respects the optimal foraging theory?

cancer crabs> abalone > urchins > kelp crabs

True or false: when there aren’t enough sea otters, ecological balance can lead to kelp elimination? 

True; urchins eat the kelp and the otters weren’t there to keep urchin pop. in check 

Describe trophic cascade

• when changes at one trophic level have dramatic effects throughout a food web

What are keystone species?

a species with an outsized influence relative to its abundance

What is the keystone species of the kelp forest?

sea otters

Are sea otters an apex predator? Are keystone species always apex predators? 

• yes, otter are apex predators in the kelp forest ecosystem 

• no, keystone species are not always apex predators