BIO DEPTH STUDY

– structural adaptations

• Anatomical or morphological features that improve an organism’s ability to cope with biotic and abiotic factors → inc. chances of survival and reproduction

  • Physical characteristics relating to body and size

In plants

• Many adaptations in plants reduces water loss caused by salinity, heat and wind

• Fewer stomata

• Stomatal hairs that create humid microclimate

• Sunken/ protected stomata

• Thick, waxy cuticle

• Reduced leaf surface area

• Extensive root system

• Rolled leaves

• Leaves oriented away from sunlight

• Leaf abscission (shedding)

• Some adaptations in hot, dry climates are similar to cold environments

  • Water freezes → inaccessible

  • Cold + dry air → transpiration

Hot, dry environments

• Xerophytes have adaptations to conserve moisture and prevent leaf temp. from rising too much:

  • Increased tolerance for desiccation (drying)

  • Leaf spines: reduce leaf surface-area-to-volume ratio → slow loss of water

  • Few stomata (pores): reduce transpiration

  • Stomatal hairs: create humid microclimate

  • Sunken/ protected stomata: create humid microclimate

  • Rolled leaves: maintain humid air around stomata

  • Thick, waxy cuticles: water retention layer → prevent diffusion of water molecules from leaf

  • Extensive water: maximise water uptake

Cool, wet environments

• Protect themselves from water loss by reducing surface area of leaf

• Deciduous plants shed leaves entirely during winter

• Alternative, leaves may have waxy cuticle

Warm, wet environments

• Has adaptations to survive environment with excess water

• Can cope with high rainfall and humidity

• Thin bark

• Thick, waxy leaves: water falls off → prevents fungal growth

• Drip tip: Funnels water off leaves

• Buttresses: Large ridges at base of some rainforest trees

• Stilt roots/ prop roots: Rapidly growing above-ground root systems

• Epiphytes: Plants that grow on other plants (ivy, creepers)

In animals

• To cope with temperature, water availability, predators, prey, competitors…

• Thick fur and blubber

• Bright feathers

• Large/ small ears

• Webbed feet/ flippers

• Spines for protection

• Overall body shape and size

• Patterned body

Surface area to volume and structural adaptations

• Larger surface area to volume: Cool down + heat up quicker

  • Hot, dry climates

• Larger volume to surface area: Conserve body heat

  • Cold, icy climates

• e.g. tiny desert cat and alpine snow leopard

• Variations to rule: Larger body size experiences advantages such as catching larger prey-- benefits outweigh advantage of being small (eg. lions)

Vascular body parts

• Animals in hot climates may have large ears, long tails or long body

  • Extremeties r often highly vascular: Contain blood vessels

  • Enables animals to release body heat to the external environment → keeping bodies cool

• Overheated → blood vessels expand → flow closer to surface → COOL

• Cold → vessels constrict → flows away from surface area → CONSERVES HEAT

– physiological adaptations

• Features that affect the functioning of an organism at different levels of organisation

In plants

Crassuleacean acid metabolism (CAM)

• Reduces water loss in plants

• Most commonly found in plants living in dry environments (succulents etc.)

• CAM pathway: some xerophytes and plants adapted to saline conditions and can minimise water loss

• In CAM plants, stomata only opens at night to collect carbon dioxide

• Stores in cell vacuoles as organic compound called malic acid

  • DAY: Malic acid → chloroplasts → carbon dioxide (photosynthesis)

    • Store at night = close stomata during day = reduce water loss

Frost tolerance

• Ice crystals burst membrane → kills cells

• Cold temps = decrease enzyme activity, change fluidity → affect other psychological processes

• High concentration of solutes (sugars, salts) = lower freezing point

• Antifreeze proteins: inhibit growth and recrystallisation by binding to them

• Dehydrin: Bind to water molecules inside of cell → change structure of water → stabilise cell membrane

• Also changes lipid composition of cell membranes to improve function in cold environments

Salinity regulation

• Over-irrigation = highly saline soils

  • Disrupt water and nutrient uptake by altering concentration gradient

• Salt enters → ion imbalance → inhibits metabolic process → cell death

• Halophyes: Plants that can survive high salinity

Cope:

• Transport excess salt to vacuoles and old tissues

• Excluding from roots and leaves

• Shedding leaves that are overloaded with salt

• Excreting from salt glands

• Pumping from roots

• Controlling transpiration to avoid excess salt being delivered from soil to shoots

• Balancing rate of growth with uptake of soluble ions → maintain constant salt concentration in tissues

• Upping water intake → dilute salt concentration

In animals

• Producing concentrated urine → conserving water (spinitex hopping mouse)

• Venom

• Colour changing → sunlight, aiding in thermoregulation

• Shivering → maintaining body temperature when cold in endothermic animals (humans)

Camouflage

• Avoiding predators and catching prey

• Chromatophores → changing colours to match surroundings

• Move pigment to and from cells → change reflective characteristics to produce camouflage

Evaporative cooling

• Adults can sweat up to 4L/h with intense exercise

• Sweat in contact to cool air → evaporates → carries heat away → lower body temp

Heat exchange for cooling

• Heat exchanger to keep brain cool

• Hot arterial blood → smaller network → brain (carotid rete system)

• Venous blood in carotid rete system travelled through nasal system, has been cooled using evaporative cooling in nostrils

  • Cooler blood || warmer blood from body, heat flows from hotter to cooler blood in neighbouring network of cells = countercurrent heat exchange

Heat exchange for heat

• Blood flows to heart through veins close to the arteries

• Warm blood in arteries transfers heat to the veins to warm blood moving back towards the heart

• Diameter of arteries also reduced → decrease blood flow, reduce heat loss

  • Vasoconstriction

Deep diving

• Mammals can carry out anaerobic respiration (respiration in absence of oxygen)

• High tolerance for lactic build up

• Excellent control over organs → reduce blood flow for those unneeded for immediate survival → slows heart rate, conserves oxygen

Torpor

• State where metabolic state is slowed to save energy

  • Allows them to cope with environmental stresses: extreme cold/ heat, decreased food availability

• Hibernation: Over winter, work to get thick layer of body fat → energy during hibernation

• Brumation: Before winter, 1-8 months, depends on air temp. size + age

• Aestivation: Hot and dry conditions

Bioluminescence

• Light produced to attract attention, frighten enemies, lure prey

• Form chemiluminescence

  • Release of light energy following a chemical reaction

– behavioural adaptations

• Actions or movements that an organism performs in response to its environment to improve survival or reproduction

Module 4: Ecosystem Dynamics

Population Dynamics

Inquiry question: What effect can one species have on the other species in a community?

• investigate and determine relationships between biotic and abiotic factors in an ecosystem, including: (ACSBL019)

The impact of abiotic factors (ACSBL021, ACSBL022, ACSBL025)

• Organisms face selection pressures from biotic and abiotic factors in the environment that affect their survival and thus drive evolution

  • Temperature

  • Water availability

  • Seasonal changes

  • UV/ Sunlight exposure

  • Food/flora

  • Predation

  • Diseases

    • Bacteria/ viruses, fungi → living

Biotic and Abiotic Factors

• Organisms that are able to access their basic requirements for growth, reproduction and survival through their interactions with different factors in their environment

  • Biotic factors are the living components of an environment

  • Abiotic factors are the non-living components of an environment

• Can either be beneficial or detrimental to the survival of an organisms

Abiotic factors

• Belonging to the atmosphere, lithosphere and hydrosphere, and their interactions with each other create selection pressures for organisms:

  • Atmosphere: Layer of gas around Earth

  • Lithosphere: Outer layers of Earth (crust, upper mantle)

  • Hydrosphere: All liquid on Earth

e.g 

• Birds detect subtle changes in the air pressure using an ‘internal barometer’, allowing them to change flight paths

• Banksia seed pods open following the extreme heat of a bushfire, allowing seeds to release and germinate

 the impact of biotic factors, including predation, competition and symbiotic relationships (ACSBL024)

Keystone species

• Species that play critical roles in the structure and functioning of an ecosystem

  • When removed, it becomes unstable

  • Selection pressures in an ecosystem are likely to be significant with consequences for diversity and abundance

e.g.

• The Great White Shark → top of food chain, keeps seal, fish and sea lion numbers stable

• Northern Quoll (native cat) → endangered due to bushfires and feeding on poisonous cane toads

          → Feeds on a number of prey, keeping number stable 

• African elephants → eat small trees

     → without them, savannahs: invaded by shrubs, become forest eventually

• Pisaster sea stars → removed from one rock pool and left undisturbed in another as a control

    → remaining competed for space and resources

    → two types of barnacle and mussel populations started dominating while limpet 

          population declined

Organism tolerance

• Particular range of conditions in which it can survive → tolerance range

• Have an ideal range for each abiotic factor that is favourable for the growth, development, reproduction and survival of the organism

  • Experiences stress if it encounters conditions out of its ideal range in a particular factor

Human impacts on abiotic environments

• Deforestation

• Land degradation

• Runoff

• Urbanisation

H.I on biotic environments

• Overfishing

• Artificial selection

• Hunting

Biogeography

• Study of species’ distributions to understand their evolutionary past and the biotic and abiotic factors that might determine species’ abundance and distribution now and in the future

• High biodiversity → linked to climate and latitude

• Species richness increases from poles to the equator, highest being tropics near equator

Ecological relationships

• Interspecific interactions → between species

  • Feeding, non-feeding

  • Predation

• Intraspecific interactions → within species

• Competition and predation → organisms acting in opposition to one another

• Symbiosis → working together

Competition 

• Struggle between organisms for the same supply of environmental resource that is in limited supply

  • Water, food, space, mates

• Leads to one species being forced out by competitor

• Competitive exclusion: One species is better at obtaining resources, excluding the other from the available resources and sometimes driving them to extinction

• Resource partitioning: Species changing their behaviour and resource use, allowing both species to access resources in the same environment

Predation

• Involves one animal species killing and feeding on another animal

• Predators are carnivores and benefit from the relationship while prey is harmed

  • Wolves and elk, owls and mice etc.

Symbiosis

• Relationship where two quite different organisms live in and function together in close association, to the benefit of at least one of them

  • Mutualism

    • Obligate, facultative

  • Commensalism

    • Only one species benefits but other is unaffected

      • Bird nesting in tree hollow

  • Paratism

    • One species benefits, other is harmed

      • Tick on blood of dog, dog may contract disease

    • Ectoparasites live outside the host

    • Endoparasites live inside the host

    • Host that transfers a parasite to another is a vector

  • Amensalism

    • One is inhibited or killed and the other is unaffected

      • Cattle tramping on grass

• Obligate mutualism: Both species are completely dependent on each other for survival and reproduction, one cannot survive without the other

  • Yucca plants rely on yucca moth to pollinate, yucca moths rely on plants for safe space to hatch eggs

• Facultative mutualism: Both species benefit from interacting but do not rely on each other for survival

  • Zebras have parasites removed while oxpeckers have easier access to a food source

Feeding interdependencies

• Make species in a food web vulnerable to changes in their ecosystem

• Ecosystem changes can present new selection pressures that cause the extinction of species or lead to organisms adapting to the new conditions

 the ecological niches occupied by species (ACSBL023)

• A niche is a role an organism occupies in its environment, including how an organism:

  • Uses its resources

  • Interacts with other species

  • Interacts with its environment

Competitive exclusion principle

• States how two species cannot have the same niche in an ecosystem

• If two competitors try occupying same ecological niche, one will be eliminated

  • May be done through one species becoming extinct, or adapting to fill a different ecological niche

Resource partitioning

• Diff. species using diff. parts of a resource at the same time to avoid competition, risk of endangerment and extinction

Carrying capacity

• Maximum population that can be supported by an ecosystem

  • Due to limited resources

predicting consequences for populations in ecosystems due to predation, competition, symbiosis and disease (ACSBL019, ACSBL020)

Consequences of predation

• Predators affect the distribution and abundance of their prey

  • Natural population control

  • Unless the prey species can reproduce faster, population will remain stable

Factors affecting number of prey and predators

• No. of predators competing for same prey

• Availability of prey food

• Reproduction rate:

  • Age of reproduction maturity

  • No. of reproduction episodes per lifetime

  • Fertility (likelihood of fertilisation at a reproductive episode)

  • Fecundity (number of offspring per reproductive episode)  

• Death rate (increased by exposure to disease, reduced availability of resources)

• Ratio of males to females

• Size of ecosystem

• Movement between ecosystems

• No. of shelter sites available

Consequences of competition

• Affects reproduction and survival rates

• Population fluctuations → directly linked to competing species and their resources

  • If a resource is a common food source (e.g. food sources become more readily available, abundance of both increases. As food decrease, so does abundance of both species)

  • Some species may be more successful than others

• In most instances, one species is more successful than the other and population numbers drop more significantly than the other (increase in deaths, decrease in reproduction rates)

• Depending on supply of the resource, ability of the ‘losing species’ to adapt by occupying a different niche or environmental factor, trend may change or reverse

• Trend of one species outcompeting continues → long periods of decreased reproduction rates + increased deaths → elimination of ‘losing species’ → POSSIBLE EXTINCTION

Consequences of symbiosis

• Profound consequences for all life on Earth

• Potential to:

  • Increased evolutionary diversification - biodiversity

  • Development of new species from integration of their genetic material with each other (symbiogenesis)

  • Source of new capabilities for organisms, enhancing evolutionary ‘fitness’

• Increase in biodiversity → resilient ecosystems

  • Coral reefs r only possible from the symbiotic relationship w photosynthetic algae

    • Provide unique environment for fish and marine invertebrates

example of symbiogenesis:

• lil baby eukaryotic organisms on early earth… no aerobic respiration → acquired through symbiosis of primitive mitochondria-like organisms around 1-2billion years ago

Consequences of disease

• Disease: Any process that adversely affects the normal functioning of tissues in a living organism

  • Infectious and non-infectious causes

    • In wild ecosystems, infectious diseases are generally the greatest threats

• Usually a pool of disease causing agents or pathogens (virus, bacteria, fungi) already present in the environment

• For outbreak to occur: Pathogen must be introduced through direct or indirect contact means, or given a selective advantage by change in biotic or abiotic conditions

  • Human induced changes can also contribute

  • May lead to:

    • Inc no. breeding sites for vectors

    • Invasion of ecosystem by new pathogen/ vector

    • Changes in resistant populations of organisms due to use of antibiotics and pesticides (herbicides, insecticides, fungicides) by humans

    • Lowering resistance to disease in species due to changes in environment

Predicting consequences for populations

Selection pressure: population changes

• Population density and size r determined by a variety of factors that influence rates of birth

  • Immigration, emigration, death

• Geographical distribution is all the places where a species is found

• To investigate changes in population, distribution and abundance is required

• Methods depend on size, mobility and location of organism

Environmental resistance

• Factors that limit the growth of populations due to reduction in health, reproduction rate and survival

  • Either density dependent or density independent

Tolerance range

• Physical conditions that an organism can tolerate and survive

• Determined by genes (genotype) and traits (phenotype) that allow it to adapt to its environment

• Optimum range: Best suited to the environment and can outcompete other species

• Stress zone: Can survive, but may be outcompeted

Major changes to environment

• Natural disasters

  • Drought, volcanic eruptions, tsunamis

• Anthropogenic changes

  • Construction, pollution

Crowding

• Can cause organisms to:

  • Develop adaptations to survive the conditions or find resources

  • Fewer offspring to accommodate to high density

  • More susceptible to disease: weakened immune systems

Population explosion

Exponential population growth

• Populations not limited by resources, predators or disease can experience continual, unlimited growth

• Individuals continue to reproduce regardless of population size → growth increases each generation

  • Usually limited by carrying capacity

• Periods of plentiful resources typically last only a short time, however if continues, can lead to population explosion

BIOTIC AND ABIOTIC

Selection pressures: all the biotic and abiotic factors in an organism’s environment that affect the individual’s behaviour, survival and reproduction.

Selection pressures cause evolutionary change due to natural selection. 

Biotic factors are the living components of an environment.

Abiotic factors are the non-living components of an environment.

Abiotic factors belong to the atmosphere, lithosphere and hydrosphere.

• Light

• Temperature ---> Dormancy

• Weather 

•  Water

• Shelter 

• Topography

The aspect (the direction a slope faces) causes variation in the amount of sunlight received by an area of land.

As altitude increases, air pressure and temperature decrease, as well as the amount of readily available oxygen.

Terrestrial landscapes are soil. Soil is essential for the exchange of gases, nutrients and water, and for structural stability in terrestrial plants.

• Chemical Components

The nitrogen in the atmosphere, lithosphere and oceans is converted to accessible forms to be used for protein synthesis in living organisms.

Nutrient cycles = biogeochemical cycles

Tolerance Range: Every organism has a particular range of conditions in which it can survive.

If an organism is outside its tolerance range, development may be delayed, and health, reproduction and lifespan may be negatively affected. At a certain point, the organism will die.

HUMAN IMPACT:

• Deforestation 

• Land degradation 

• Runoff 

• Urbanisation 

Our human activities have caused new or altered selection pressures on organisms. (MOSTLY NEGATIVELY SO THEY HAVE A LOWER SURVIVAL RATE) EG. POLLUTION

Habitats and microhabitats are specific parts of an ecosystem that populations of organisms use for shelter, obtaining resources, breeding and raising offspring.

Keystone species: Species that play a critical role in maintaining the structure of an ecosystem.

If they are removed, there are consequences for both the diversity and the abundance of all species within the ecosystem.

Keystone species are frequently targeted for conservation efforts. Eg. Yellowstone wolves.

WE AFFECT BIOTIC ENVIRONMENT:

Artificial selection: selectively breeding organisms with specific traits to increase the number of offspring with these desired traits. EG. Hens lay bigger eggs

Overfishing

Artificial selection 

Hunting 

Population distribution

• Random

• Uniform

• Crumpled/clustered

Population distribution affected by:

• Physical enviro

• Characteristics of species

• Behaviour of an organism

Population growth

• Birth 

• Migration, both immi and emi

• Death

• Exponential growth of the population is technically possible

• however the environment has a physical capacity

CANE TOADS & PRICKLY PEAR

PRICKLY PEAR

Drought-resistant

fewer stomata (pores) in leaves = reduce transpiration

Thick waxy cuticles = water retention layer

Leaf spines reduce surface area = slower loss of water in hot environments

When eaten by emus and other organisms, it doesn’t get digested, so it just allows it to continue growing in any available spaces it is dropped by the animals

They have cactoblastis moths that the larvae eat and destroy the plant in a few weeks

CANE TOADS

Has no known predators

Produce bufotoxin, which causes death in predators

Legit nothing to manage it, and everything below them gets eaten by them

No available long-term, effective, broad-scale control of cane toads