habitats, environment and survival -...

Unit 2: Adaptations of Organisms

HABITATS, ENVIRONMENT AND

SURVIVAL

HABITATS• Is the location or place where an organism lives at a

given time – organism’s address.

• Habitats of different organisms vary greatly. Compare the habitat of kelp seaweed, fairy penguin and tree kangaroo.

• Is the natural setting where an organism can obtain food, shelter and can reproduce

• Within a habitat there may be many different organisms living there and so the conditions may be different. The more localised part of a general habitat where an organism lives is its MICROHABITAT.

Eg. Living on pond weed within a pond.

Habitats continued…

• ‘Extreme environments’ – some living spaces that appear hostile (human perception).

Eg. Salt lakes, under boulders on glaciers, etc

• Habitats can be described in general terms as:1. TERRESTRIAL – on land (eg. Deserts, rainforests, etc)2. AQUATIC – in water

Eg. Freshwater – lakes, rivers, pondsmarine (salt water) – coral reefs, open oceanestuarine – river mouths

• Members of the different species that share one HABITAT form the living COMMUNITY of that habitat.


• A habitat provides the resources an organism requires for life.

ie. Plants- sunlight, space, water and mineral nutrients.

Animals- food, water, shelter, nesting and breeding sites

• The distribution of resources is not uniform.

eg. In the habitat of a particular animal, its feeding area may be different to where it breeds or nests.


MAPPING HABITATS• The geographic area that encloses all the habitats where

a species lives is called a RANGE (= distribution map)

• The size of the range does not represent the abundance of the species

Present range of the Numbat (Myrmecobius fasciatus). Their range is shrinking because of feral predators.

Habitats continued…A species being absent from a region maybe due to:• Conditions are not favourable for survival and

reproduction• Competition for the same resources

A decrease in the range of a species may be due to:• Disease or natural disaster• Introduction of an exotic species which is a better

competitor• Over-exploitation – hunting may remove breeding pairs• Habitat Destruction – felling of trees in a forest, damming

rivers

Habitats continued…MOVING BETWEEN HABITATS• Predictable movements by organisms over large

distances are known as MIGRATIONS

• Migrations can occur only once in a lifetime e.g. Salmon is seasonally based

• Migrations can occur annually e.g. humpback whales (see p.262 of text)

• Species that do not have predictable movements are said to be NOMADIC. Food being the driving force behind the moving (e.g. wilderbeast)

• Species that stay put and feed & breed in the one place are SEDENTARY

Using technology to study habitats• Areas of vegetation too vast and movement of

animal species to frequent for humans to record in the field with a notebook.ANSWER: Technology

Monitoring Vegetation• Remote sensing uses satellites that carry

sensors that can detect the distinctive ‘signatures’ of different kinds of vegetation.

• Data collected is converted to colour-coded images that show the distribution of a particular vegetation type.

Using technology to study habitats continued…

Monitoring Animal Movements• Radio tracking (telemetry) – identifies the

position of animals as they move within their habitat.

• Animals need to be of sufficient size to carry a tracking device without it interfering with normal activity.

• The early technique involved capturing the animal and fitting a collar (or the like) to it. The scientist then had to walk around the habitat area with antenna unit to receive the signal.

Using technology to study habitats continued…• Satellite tracking requires a more powerful transmitting

tag to be fitted and can track animals across large areas of land and ocean.

• Each tag transmits a unique code relating to a particular animal.

• E.g. monitoring White Sharks using a tag pinned to the dorsal fin that transmits to the satellite every time the animal surfaces.

• Pop-off archival tag (PAT) – programmed to collect data every few minutes over a given period and then detaches from the shark.

• Once the tag reaches the surface it then transmits the information stored.

Refer to other examples on page 267 of texthttp://www.cmar.csiro.au/research/sharks/whitesharks/wsresearch.html

http://www.cmar.csiro.au/research/sharks/whitesharks/wsresearch.html

NICHES• NICHE refers to the ‘way of life of a species’ OR the role of a species in a community OR the status or role of an organism in its habitat

• A niche can be explained using the example of a human population within a city.- groups of people are identified by their way of life, e.g. educator, surgeon, security guard, etc- each group can then be subdivided, e.g. the educator role includes: pre-school teachers, biology teachers, etc

• A niche can be identified in terms of the degree of use of resources e.g. where it lives, what it eats, when it feeds

Niches continued…

STUDENT ACTIVITY

• Copy the ‘Terms describing feeding niches of animal species in a community’ in the left-hand column on page 269 of text, and include 2-3 different examples of animals for each.

Niches continued…

Niche Overlap• Different species in a community have zero to

low niche overlap because they are not in direct competition for the same food and space resources at the same time.

• If there is a high degree of overlap in the degree of use of resources then COMPETITION between species occurs. If the overlap persists, then one species may perish

• Competition is avoided when various species in a community occupy niches that differ in some aspect of use of resources

THE ENVIRONMENTSTUDENT ACIVITY: Eucalypt Forest Scenario

• Environment- the physical, chemical and biological conditions that exist in a habitat.– Sum total of external influences acting on an organism.

• Habitat- location or place where an organism lives.– Need to obtain energy and matter required for living.– Conditions are suitable for survival and reproduction.

• Environmental factors- factors that act on an organism in its habitat to produce a particular environment.

• Separated into abiotic (non-living) and biotic (living).• Factors important in one habitat may be irrelevant in

another habitat (eg. Wave height is irrelevant to a koala).

BIOTIC FACTORS• Factors that relate to other living things present in the habitat.• May be members of same or different species.

ABIOTIC FACTORS• Are the non-living factors relating to soil, water, air, light,

topography, etc.• Abiotic factors are measured when studying an ecosystem.• Abiotic factors determine what PRODUCERS inhabit an

ecosystem. How?

Describing environmental conditions can be done in 2 ways:– QUANTITATIVELY: a numerical value or range of values is

given e.g. wave height if from 0 – 3m– QUALITATIVELY: description in a phrase e.g. warm, humid,

shady

Within any environment many MICRO-ENVIRONMENTS may exist e.g. within the vegetated area of billabong the temperature may be warmer than towards the middle where the water is deeper.

The environment in a habitat at a given time is produced by the action and interaction of several factors.

Consider the two environments below.• In which habitat would water run-off be greatest?• In which habitat would soil erosion be greater?• In which habitat would you find greatest biodiversity?• What factors interact to make habitat A more arid than

habitat B?

DenseSparseVegetation cover

SandImpermeable claySoil type

FlatSteeply slopingGradient of surface

ModerateModerateWind speed

TemperateTemperateTemperature

LowLowRainfall

VALUE IN HABITAT BVALUE IN HABITAT AENVIRONMENTAL FACTOR

Biotic & Abiotic Environmental Factors Affecting A Crocodile

Soil and water chemistrySalinityCompetitors

Humans

Air temperature

Relative humidity Solar radiationAtmospheric gases

Day length

Parasites

Prey

TOLERANCE RANGE• The Law of Tolerances states that:For each abiotic factor, an organism has a range of

tolerances within which it can survive. Toward the upper and lower extremes of this tolerance range, that abiotic factor tends to limit the organism’s ability to survive.

• Examples of abiotic factors: temperature, pH, salinity, turbidity, humidity, water pressure, light intensity, oxygen conc.

• The wider an organism’s tolerance range for a given abiotic factor, the more likely it is that the organism will be able to survive variations in that factor.

Tolerance range continued…

Tolerance range continued…• It an environmental factor has a value above or

below the range of tolerance of an organism, that organism will not survive unless it can escape from or somehow compensate for the change.E.g. migration, retreat underground, hibernation

• The wider the tolerance range of a species, the more widely dispersed the organism is likely to be.

• Organisms also have a a narrow optimal range within which they function best. Organisms will usually be most abundant where the abiotic factors are closest to the optimal range.

Tolerance range continued…

• LIMITING FACTOR – any condition which approaches or exceeds the limits of tolerance for an organism. Terrestrial and aquatic environments can differ in terms of their limiting factors.

• The kinds of organism found in various habitats are determined by their ability to survive in the prevailing environmental conditions.

• Examples:floor of tropical forest light intensitydesert water availabilitylittoral zone desiccationpolar region temperaturestagnant pond dissolved oxygen levels

Design a ’tick-the-box’ table identify which environmental measurements would be most useful in a study of the ecosystems

listed.

Peat bog

Soil

HumidityDiurnal changes in a small pond

Specific ionsOpen field

Dissolved oxygenWoodland leaf litter

pHEstuarine Mudflat

Light intensityOcean waters

Wind velocityPolluted stream

TemperatureFresh water stream

PYSICAL PARAMETERECOSYSTEM

THE AUSTRALIAN ENVIRONMENT

Average maximum temperatures

• The maximum temperature varies across the country and there is also a seasonal difference.

• Maxima in mid-summer (January) are much higher than in mid-winter (July)

The Australian environment continued…Average annual rainfall• The Australian continent has a lower rainfall than

any other inhabited continent.

• Almost two-thirds of the continent is arid (less than 250 mm annual average rainfall) or semi-arid (between 250 and 500 mm).

• In southern Australia, most rainfall occurs in the winter months and the summer is typically a period of drought.

• In northern Australia, rainfall occurs principally in the period from November to April, called ‘the wet’, and the period from May to October is known as ‘the dry’.

The Australian environment continued…Reliability of annual rainfall and incidence of drought• In inland Australia no surface water exists, apart from

periods after heavy rain when temporary creeks and ponds are created.

• These bodies of water (termed ephemeral – transient, temporary) do not last long because of the high evaporation rates.

• Drought – when the rainfall in an area fails, regardless of whether this is an area of high or low rainfall.

• Drought conditions occur when the total monthly rainfall over a period of at least 9 to 12 months falls below the lowest 10% of all values recorded.

• El Niňo and La Niňa – events over the Pacific Ocean that affects the Australian weather, every 2 -7 years.

The Australian environment continued…Soil nutrient levels• Soil is derived from very ancient rocks covering the

continent, that have low levels of mineral nutrients.

• Over long periods, mineral nutrients are lost from soil when they are dissolved and washed away. This is called leaching.

• Soils are enriched again by volcanic eruptions that bring back mineral-rich soils.

• Due to no volcanic activity soils are depleted of mineral nutrients such as phosphates and nitrates.

• To survive in low-nutrient soils some plant species have nitrogen-fixing bacteria living in nodules on their roots. Others adapt by becoming carnivorous and using the nitrogen in insect protein (eg. Sundews)

VEGETATION TYPES IN AUSTRALIA• Vegetation is divided into types or structure rather than

identifying all the individual plant species.

Woodlands and Forests• Both characterised by the presence of trees. Shrubs (<2m

high) and trees (>2m) are both woody plants. Trees are classified as tall (>30m), medium (10 to 30m) and low (<10m).

• Forests differ from woodlands in terms of light penetration or how much of the sky is covered by upper canopy.Woodlands – <30% sky coverageForests - closed = coverage of 70-100% (eg. Rainforest)

open = coverage <30% (eg. Eucalypt forest)

Vegetation types in Australia continued…

Different vegetation types can be further defined by:

• Climate - such as tropical, temperate, semi-arid or arid.

• Dominant plant specie – such as forests dominated by eucalypts and shrubland dominated by acacia

Why can’t rainforests be defined in terms of a dominant plant genera or species?


1. Hummock Grassland• Dominant vegetation type in Aust that covers nearly

25% of surface.• Found in arid inland areas and are dominated by

spinifex grasses and porcupine grass that are drought-resistant.

• Important habitats for native mammals and reptiles of the arid zone.


2. Acacia Shrubland• Cover more than 8% of surface and dominated by

mulga, one of the many hundreds of Acacia species native to Aust.

• Found in arid inland areas.

Vegetation types in Australia continued…3. Chenopod Shrubland• Cover about 6% of the surface.• Dominated by saltbushes and bluebushes, both which are

salt-resistant and drought-resistant.

Vegetation types in Australia continued…4. Eucalypt Woodlands• Cover about 9% of land mass.• Occur in higher rainfall areas than the vegetation types

mentioned above


• Vegetation types that now cover less than one percent of the surface are rainforests and heaths.

• Limiting factor in arid areas is water availability which means vegetation is sparse, individual plants are well separated and growth rates are low.

• Compare this to the limiting factor of light in a rainforest where plant growth is luxuriant, plants are crowded and growth rates are fast.


PATTERNS IN PLANT DISTRIBUTION• Distribution of vegetation types is influenced by

environmental factors mainly related to climate, but also by other factors including soil type and soil salinity.

• Plants adapted to a particular environment typically have a range or distribution map that includes areas that have particular environmental conditions.eg. Hummock grasslands have plants that are adapted to living and reproducing in the arid and semi-arid regions.

SURVIVING IN ARID ENVIRONMENTS: PLANTS

MAXIMISING WATER INTAKE• Water uptake is via the root system

• Trees growing along dry creek beds produce long (up to 30m), unbranched roots to penetrate water table. Here they develop lateral roots.

• These plants are called water tappers and the root located near the surface is covered in a corky water-proof layer that prevents water loss.

• Other plants develop extensive horizontal root systems just below the surface that can extend past the tree canopy.

Surviving in arid environments continued… REDUCING WATER LOSS• The loss of water vapour by evaporation from

moist surfaces inside s plant is called transpiration.

• Water loss occurs through pores known as stomata (singular: stoma) that are typically present on the lower surface of plant leaves.

• Rate of water loss depends on wind speed and temperature of the leaf.

Surviving in arid environments continued…

Some adaptations seen in plants that reduce water loss include:

• Fewer stomata on leaf surface – reduction in transpiration

• Period of stomatal opening is night time – lower temps means less transpiration.

• Sunken stomata – stomata are located in pits below leaf surface and create a region of high humidity that slows water loss.

• Thick waxy cuticle – this waterproofs the leaf surface so that water loss is only through stomata.


• Hair on leaf surface – slows airflow over the leaf surface and reduces loss of water vapour.

• Small leaves – reduces surface area.

• Glossy leaves – reflects the sun’s heat and keeps leaves cool.

• Infolding of leaves – slows the airflow over the leaf surface and creates a region of higher humidity within the leaf.

Surviving in arid environments continued…Diagram on left shows normal leaf cross section.

Diagram on the right shows cross section of a rolled leaf.

(NOTE: hairs in the middle trap moist air and reduce transpiration.


PRODUCING SEEDS FOR SURVIVAL• Plants with different life spans are grouped as follows:

Annuals – germinate, flower, set seed and die over one year.Biennials – germinate and grow in the first year and flower, set seed and die in their second year.Perennials – grow and reproduce over many years.

• Herbaceous flowering plants that germinate from seeds, then flower and produce new seeds in a very short period of time (life cycle could be 2-3 weeks) are called ephemeral.

• Ephemeral plants produce drought-resistant seeds that have an outer coat containing a water-soluble chemical that inhibits germination. When heavy rains fall, this chemical is dissolved away and the seeds germinate. Shortly after the new plants produce flowers in a synchronised display and soon die, but not after they produce seeds of their own that will lay dormant for another year.

Label the diagram of a Mulga bush below using points from page 288 of text. Write notes on how that plant survives in low rainfall areas.

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SURVIVING IN ARID ENVIRONMENTS: ANIMALS

• Animal species are regarded as being ‘successful’ in a particular environment if:

2. individual animals survive to reproductive age and3. mature animals reproduce and give rise to sufficient

numbers of offspring to ensure survival of the next generation.

• The presence of free water in arid and semi-arid regions is often temporary and exist only during the we season.

• Species that depend on free water need to survive the long dry periods between when the creation of ephemeral lakes and ponds.


SURVIVE BY FLIGHT

• Some species cope by emigrating from drought- affected areas to areas where lakes and rivers exist.

• For example, banded stilts rely on brine shrimp as a main food source, so when one salt lake dries up hey fly to another.


SURVIVE BY DORMANCY• Some frog species that live near and breed in

ephemeral waterholes will burrow deeply into the soft mud and eventually down about 30cm.

• Here they seal a chamber with mucous and go into an inactive state known as dormancy in which breathing rates and heart rates are minimal, therefore energy needs are minimal are fat from their fat reserves.

• Frogs come out of dormancy when heavy rains penetrate deep into the soil.

• They then return to the surface where they feed and breed in temporary pools. The completion of the life cycle is very fast.

Surviving in arid environments continued…SURVIVE BY THE NEXT GENERATION• Some species are unable to survive long dry periods as

adults and therefore survive through their offspring. This occurs in crustacean species, eg. Fairy shrimps and shield shrimps.

• As waterholes begin to dry fairy and shield shrimps produce drought-resistant eggs. The adults die but the eggs left can withstand desiccation for long periods.

• The eggs can lay in a state of dormancy for more than 20 years.

• When the drought breaks and waterholes temporarily refill, embryonic development begins and within a few days the next generation of shrimps have matured and quickly reproduce.


LEFT: Fairy Shrimp RIGHT: Shield Shrimp


SURVIVE WITHOUT WATER• The fawn hopping mouse (Notomys cervinus)

can survive its arid habitat without drinking water, even when its diet consists of dry seeds.

• The water needed for living cells comes from cellular respiration.

• It can survive on internally manufactured water because the mouse conserves water by producing very concentrated urine and very dry faeces.

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