ecology

ecotherm

regulate body temp via energy exchange with the enviroment

• cold blooded

• ex. sunlight, warm surfaces

• they lack baseline "leaky" cellular burn and have far fewer mitochondria, so their cells simply don't generate enough heat at rest.

• Even if an ____ could suddenly boost its metabolic heat output, that heat would instantly radiate away into the air or water.

• digestive system and metabolic pathway are optimized to operate on very few calories. They cannot process food fast enough to supply the constant fuel required for endothermy.

endotherm

rely on internal heat generation (mostly birds and mammels)

• warm blooded

• ex. shivering, sweating

• cells are packed with mitochondria, and their cell membranes are intentionally "leaky" to ions . Pumping these ions back and forth constantly burns ATP, which generates continuous internal heat.

• enzymes are evolutionary fine-tuned to function within a very narrow, high temperature range. If an ____ allows its body temperature to drop to match a cold environment (hypothermia), its cellular enzymes slow down dramatically, leading to loss of consciousness and death

basal metabolic rate (BMR)

minimum energy (calories) an organism needs to stay alive at complete rest

problem with small aquatic ectotherms

• metabolic heat made by swimming instantly loses internal energy, resulting in being in the same temp as water

regional endothermy/ mesothermic

• trick where ectotherm keeps warmer than enviroment

• tuna keep muscles contracted and use special netowrk of bloodvessels to keep blood warmed and cycling away from spine, warming new cold blood

terristerial ectotherms ____ to adjust temp

move around

insects and reptiles stay safe using

camoflauge

avoidance of the cold in ectotherm include

• seasonal migration

• microsites

• main goal is to avoid damage from ice formation in cells

glycerol helps

lower freezing point of bodily fluids

• keeps ice crystals outside cell

vertebraes do not tolerate freezing because

• ice crystals physically damage cells

• result in severe osmotic dehydration

• blocked circulation

In animals that withstand freezing, the freezing water is limited to _____

the space outside the cells

• ice nucleating proteins outside the cell controls ice formation

• glucose and glycerol are made inside the cell to lower freezing point

The cost of being endothermic is a high demand for

energy (food) to support metabolic heat production

Thermoneutral zone

range of environmental temperature that a constant BMR can be maintained

• The range of outside environmental temperatures where an endotherm maintains its normal body temperature

• Inside this temperature window, the body doesn't spend extra metabolic energy shivering or sweating to stay regulated

lower critical temperature

when heat loss is greater than metabolic production ; body temp drops and heat generation increases

• temp below the lowest temp body can handle

• Because heat is escaping faster than the baseline engine can generate it, the body must ramp up active heat production

• The colder it gets below the LCT, the higher the metabolic rate must go to prevent core body temperature from dropping

incipient species

a population of organisms in the early, ongoing process of speciation where they begin to diverge genetically but can still occasionally interbreed

autotroph

assimilate radiant energy from sunlight or inorganic compounds

• energy is converted into chemical energy stored in bonds of organic molecules

• ex. photosynthesis, chemosynthesis

heterotroph

obtain energy by consuming organic compounds from other organisms

• some consume non-living matter

• parasites and herbivores consume live hosts but don’t kill them

• predators capture and consume live prey

holoparasites

plants that are non-photosynthetic

• get energy from other plants

dodder

holoparasite that’s an agricultural pest and can significantly reduce biomass in host plant

hemiparasite

photosynthetic plant but still obtains nutrients

• ex. mistletoe

photosynthesis

• sunlight provides energy to take up co2 and synthesis organic compounds

• light reactions (light absorptions) + dark reactions (co2 is fixed and uses light energy to synthesize carbs)

• most common source of energy on earth

photosynthetic rate

determines supply of energy which influences growth and reproduction

light response curve

show influence of light levels on photosynthetic rate

light compensation point

where co2 uptake is balanced by co2 loss by respiration

photosynthesis (co2 uptake) = cellular resp (co2 loss)

saturation point

when photosynthesis no longer increases even when more light is absorbed

chemosynthesis

energy from inorganic compounds is used to produce carbs

• important in nutrient cycling bacteria and some ecosystems like hydrothermal vent communities

• autotrophic process

• specialized bacteria and archaea build organic food from carbon dioxide using energy harvested from inorganic chemicals instead of sunlight

primary pigment for light harvesting

chlorophyll

plants can acclimatize to

changing light intensities

• In high light, a plant builds thick, dense leaves packed with extra enzymes (like Rubisco) and photoprotective pigments, allowing it to process intense energy quickly without overheating

• in low light, the plant lowers its baseline energy bill by reducing excess enzymes, building broad, paper-thin leaves that maximize surface area to catch every stray photon, thereby dropping its light compensation point

shifts in light saturation point involve

morphological and physiological changes

• a plant's physical structure and enzymatic machinery dictate its maximum operational capacity

• result of matching its metabolic investment to the light availability of its environment

• adjust to keep up with more or less light

photorespiration

Photorespiration is a wasteful metabolic pathway that occurs in plants when the enzyme Rubisco binds to oxygen instead of carbon dioxide

rubisco catalyzes two competing reactions

1. carboxylase reaction

2. oxygenase reaction (photorespiration)

benefits of photorespiration

• photorespiration may protect plants from damage at high light levels

• When plants absorb excess light energy or close their stomata during drought, the electron transport chain can become dangerously overloaded; photorespiration acts as a crucial "energy safety valve" by consuming surplus ATP and NADPH, preventing the accumulation of reactive oxygen species (ROS)

• Photorespiration is a large disadvantage if co2 is low and temp high

C4 PHOTOSYNTHETIC PATHWAY

• evolutionary adaptation that prevents photorespiration by physically separating initial carbon capture from the Calvin cycle

• outside CO2 enters the mesophyll cells (outer layer).

• An enzyme called PEP carboxylase fixes onto phosphoenolpyruvate (PEP) to form a 4-carbon compound (oxaloacetate/malate)

• PEP carboxylase has zero affinity for oxygen, so it never makes the mistake Rubisco does, even when CO2 is low

• PEP carboxylase is broken down into CO2

• Rubisco fixes the CO2 under the normal Calvin cycle with virtually zero photorespiration

CRASSULACEON ACID METABOLISM (CAM)

• alternative photosynthetic adaptation that minimizes photorespiration and prevents water loss by separating carbon capture and the Calvin cycle by time (night vs. day)

• at night, stomata opens and co2 fixations occurs by PEP

• during the day stomata is sealed to prevent water loss

factors affecting ecological success (enviromental)

1. extreme conditions that exceed tolerance limits(stress)

2. availibility of energy (affects growth and reproduction)

3. energy supply (influences tolerance of the environment)

climate envelope

set of climate conditions—such as temperature ranges, precipitation levels, and seasonal patterns—under which a particular species can survive, reproduce, and maintain a stable population

physiological ecology

study of environmental influence on survival

• Processes have optimal conditions for function

stress

• deviations from optimal conditions

• lead to lower rates of physiological process and decreased growth and survival

acclimatization

• Adjusting to stress through behaviour or physiology

• ussually short term and reversible

• ex. climbing mount everest takes a few days to acclimatize to changing elevations

adaptation

• resulted from natural selection

• coping with stress leads to natural selection, favoured traits become more common leading to adaptation

• response to stress

speciation

when species are separated for so long that that natural selection results in them becoming reproductively isolated, become different species

ecotypes

populations with adaptations to unique environments

• Ecotypes can eventually become separate species as populations diverge and become reproductively isolated

• Members of different ecotypes are still the exact same species—they can interbreed and produce fertile offspring—but they look, grow, or function differently because natural selection has tweaked their DNA to survive local conditions

Survival and functioning of organisms is strongly tied to their

internal temperature

isozymes

special enzymes produced by some species that have different optimal temperatures, allows for acclimation to changing conditions

SA:V

• the smaller the ectotherm, the less energy it can hold but the faster it can store and lose heat

• large ectotherms can hold heat for longer

large ectotherms adjust heat by

-vasodialtion/vasoconstriction (skipjack tuna)

small ectotherms adjust by

• changing locations

• changing colour of skin

ectotherms tolerate/avoid freezing by

• seasonal migration

• relocate to microsites (underground burrows)

microsite

underground burrows that are above freezing temps

Cryonics

the preservation of bodies by freezing, in hope that they can be brought back to life in the future

The cost of being endothermic

a high demand for energy (food) to support metabolic heat production

Metabolic rates are a function of

• the external temperature and rate of heat loss

• represents the speed at which an organism burns chemical energy (ATP) to power cellular work.

• chemical reactions are sensitive to heat and heat constantly flows down thermal gradients, metabolic rate is fundamentally tied to both external temperature and the rate of heat loss.

dormancy

• state where little to no metabolic activity occurs

• method of escaping extreme heat or cold

evolution of endothermy required

insulation, like fat, fur and feathers

Mammals in the Arctic have ___ critical temp than tropical ones

lower

• can withstand colder temps without needing extra atp

The rate of metabolic activity increases more rapidly below the lower critical temperature in

tropical mammals as compared to Arctic mammals.

• tropical mamels have a higher LCT

• metabolic activity increases to tolerate freezing temps

Metabolic rate

how fast your body burns fuel (calories) to generate energy (ATP)

torpor

state of dormancy observed in mammals and birds

• Body temperature and basal metabolic rates are low, which conserves energy

methods to tolerate heat

• spray water

• open mouth

• moving to shade

• evaporative heat loss (sweating, licking), wicks away heat in form of water to gas

plants adapt to heat via

transpiration

• water that’s absorbed by plant roots evaporates through stomata

• 
  

if soil is limited

• too much transpiration results in water loss, stomata closes but then overheating may occur

• plants may shed their leaves during dry season to reduce sa that requires water

pubescence

• hairs on leaf surfaces that reflect solar energy

• lowers the total heat absorbed by the plant, keeping leaf temperatures cooler under intense sunlight

convection

transfer of heat from solid to air (traps layer of warm air)

• wind destroys

high altitude alpine plants avoid convection loss by

staying close to ground to avoid high winds

• some have insulating hair

some organisms tolerate arid conditions by

going into suspended animation (stop all metabolic processes)

torpor vs suspended animation

• torpor still maintains low levels of metabolic process, thus require high fat stores

• suspended animation consumes no atp and no reactions

reptiles are very successful in dry conditions because

• They have thick skin with layers of dead cells, fatty coatings, and plates or scales

• skin is impermeable barrier against water loss

• fatty compounds embedded in their skin layers repel water, creating an airtight seal against evaporation

sweat glands in mammels are a tradeoff between

water loss resistance and evaporative cooling

• their skin is sealed, so reptiles cannot sweat. To cool down, they rely entirely on behavior (seeking shade, burrowing) or minor evaporative cooling through their mouths (gaping)

• in mammals, Sweating releases liquid water directly onto the skin, providing unmatched evaporative cooling during intense heat or high physical activity, but It requires burning through large amounts of body water. In a desert environment where liquid is scarce, relying heavily on sweating can trigger lethal dehydration and osmotic collapse very quickly

ecology

study of interactions between organisms and their enviroment

• the distribution, locations and abundance of organisms

• how systems adjust and change during disruptioons

• 
  

species ____ play equal roles in maintaining fn of ecosystem

DON’T

hierachar of ecosystem

organism , population, community, ecosystem, biosphere

organism

individual

population

species living together at the same time, can interbreed

community

population of different species

ecosystem

biotic + abiotic in an enviroment

biosphere

all ecosystems on earth

producer

organism that uses energy from external source to produce energy

consumer

obtains energy by eating other organisms or organic matter

net primary production (NPP)

amount of energy per unit of time that producers fix by photosynthesis or other means - amount used in cellular respiration

nutrient cycle

cyclic movmeent of nutrient between organism and enviroment

cellular respiration

biochemical process by which cells break down nutrient molecules (primarily glucose) to harvest energy in the form of adenosine triphosphate (ATP)

• virtually ALL living organisms perform .

Multicellular animals also have evolved specialized

tissues and organs for absorption, digestion, transport, and excretion

Compared with omnivorous humans, herbivorous primates have longer

digestive systems

Heterotrophs have tremendous diversity in morphological and physiological

feeding adaptations

Plants that thrive at low temperatures have higher proportions of

unsaturated lipids (with double bonds) in their cell membranes

evolution is

allele frequency change

• Takes millions of years

• Due to the environmental pressures, the frequency of specific alleles changes

• change in organisms over time

directional selection

individuals of one phenotype extreme is favoured

• ex. large ram horn size favoured, over time the average ram horn size increases

Stabilizing phenotype

intermediate phenotype favoured

• ex. human baby birth weight

disruptive selection

both extremes of phenotype favoured

genetic drift

evolution caused by random events (affects size of gene pool)

• significant/damaging in small populations

• as alleles go missing, genetic variety lessens

gene flow

transfer of alleles between separate populations

• increases diversity within the population but decreases differences between the different groups

constrains on evolution

• Lack of genetic variation (natural selection can only choose from existing alleles or mutations, otherwise may be at risk of extinction if adaptation cannot occur. limits adaptation. adaptation cannot occur if beneficial allele doesn’t exist)

• Evolutionary history (organisms have physiological rules that dictate how their body can grow and change, can only adopt certain traits)

• Ecological trade-offs (every trait comes with pros and cons, must consider if energetic costs outweigh benefits)

keystone species

help define an ecosystem, has large effect on ecosystem

• controls community structure and biodiversity

large-scale processes that drive evolution

• speciation

• adaptive radiation

• extinction

evolution vs adaptation

Evolution is the overall change in the genetic composition of a population over successive generations, whereas an adaptation is a specific inherited trait or mechanism that enhances an organism's ability to survive and reproduce in its environment

• Adaptation is primarily caused by natural selection, whereas evolution is also caused by genetic drift, gene flow , mutations, and is more about change in allele frequency rather than adaptation to the environment

speciation

the process by which one ancestral lineage splits into two or more distinct, genetically independent species

• when gene flow between two populations stops, they evolve independently and eventually become reproductively isolated

adaptive radiation

when a single ancestral species rapidly evolves into a wide variety of descendant species, each adapted to a specific ecological niche or lifestyle

• when adaption occurs across many species as they adapt to a new enviroment

Extinction

• Loss of species in an ecosystem

• Extinctions occur all the time, only a few huge mass extinction events occur

• show patterns of evolutionary change

• mass extinctions can increase diversity by removing competitors and allowing survivors to rise to new species

Three types of natural selection

1. Directional selection: Individuals at one phenotypic

extreme (e.g., large size) are favored.

2. Stabilizing selection: Individuals with an intermediate

phenotype are favored.

3. Disruptive selection: Individuals at both phenotypic

extremes are favored

Evolution is viewed as

genetic change (allele frequencies), over time or as a process of descent with modification