Habitat

1. Habitat Chapter 9 p268

2. Geographic Distribution • Geographic distribution: the places where a particular species can be found. • Geographic distribution of a species changes over time due to: • Macro climate change • Catastrophic events • Human intervention • Weeds/feral animals/pests • Land clearing for urbanisation, farming and forestry

3. Examples of distributions

4. The kultarr (Antechinomyslaniger)

5. The Numbat(Myrmecobiusfasciatus)

6. The cane toad (Bufo marinus)

7. The habitat of the tamar wallaby

8. Habitat • Habitat: The type of place an organism lives. • The ‘address of an organism’ • Generally classed as either terrestrial (land) or aquatic (fresh, salt-water or estuarine (mouth of rivers) • Patterns of migration can affect habitat. • Microhabitat: • A habitat within a habitat. • Within a habitat there will be slightly different localised environmental conditions.

9. Microhabitat examples • Pockets of moisture or humidity. The trunk of the Dicksonia Antarctica (tree fern) is a microhabitat for fungi, ferns, moss, liverworts, spiders and insect. • The muddy floor of a lake.

10. Habitats are not uniform • An organisms’ habitat is not the same throughout. Some areas may provides food resources, others shelter and protection and others places to reproduce and bring up young.

11. Range • Range: The geographic extent or area that a species inhabits. • It encloses all of the habitats where a particular species lives. • A large range does not mean there are many animals and a small range does not mean there are few.

12. Migration: Moving between habitats • Many species move (migrate) between habitats in order to secure food, breeding sites or to avoid unfavourable climatic conditions. • Migration can be seasonal (annual) or once in a lifetime.

13. Migration of the humpback whale

14. The Bogong Moth (Agrotisinfusa) The bogong moth migrate to mountain crevices at altitudes over 1500m during the winter. They undergo diapause– a state of inactivity characterised by low metabolism.

15. Niche • Niche: The limits, for all important environmental features within which individuals of a species can survive, reproduce and may persist indefinitely. or • The role of a species within a community. • ‘Where various species differ in their use of food and space resources available in a habitat they are said to occupy different niches’ (See Black Swan and Chestnut teal duck example p280)

16. Niche • The structural features of an organism (e.g. Having a long or short beak) will relate to how it can exploit its habitat and therefore its niche.

17. Describing Niches • There are different ways to describe a niche. E.g Feeding niches

18. Niche overlap • Niche overlap between different species does not generally occur for extended periods of time. • This is because niche overlap would create intensive competition and one species would eventually outcompete the other.

19. Environmental Factors • Abiotic environment: the physical surroundings such as soil, rainfall, temperature, salinity and nest sites. • Biotic environment: other organisms with which an organism interacts. It could include: availability of mates, predators, parasites and food supply.

20. Commonly measured environmental factors

21. Micro-environments • Environmental conditions can vary within a localised area and these areas are called micro-environments. • For e.g. In hot, dry conditions, the underside of a leaf is exposed to differences conditions compared with the upper side.

22. Tolerance Range • Tolerance range: the range of conditions (nutrient levels, water, oxygen, carbon dioxide, light and temperature) in which an organism can survive and effectively function. • The tolerance range of a species directly determines the distribution of that species.

23. Beyond the tolerance range for temperature, these fish cannot survive.

24. Environmental factors limit species distribution • Limiting factor: An environmental factor which is an essential requirement for an organism and which is in limited supply is called a limiting factor.

25. Examples of limiting factors

26. Case Study: Distribution of marine life on rocky shores • Rocky shores are subject to specific environmental factors which limit the distribution of species by creating habitat boundaries.

27. Rocky shores are zoned according to the influence of the tide. • The effects of wind, sunlight and temperature also influence marine life in each zone.

28. Algae of the subtidal zone • Brown kelp attached to rocks – have long photosynthetic fronds which are buoyant (float).

29. Organisms of the intertidal zone • Sea grapes or Neptune’s necklace – are protected from dry conditions at low tide by sticky mucus covering and water filled bladders. Abundant on the southern coast of Australia.

30. Herbivorous and carnivorous molluscs • Barnacles • Rock pools provide protection for sea stars and crustaceans.

31. Life in the spray zone • Splash from sea spray and extreme high tides evaporates during the heat of the day concentrating salt on the rock. Combined with low temperatures at night few species can tolerate these conditions. • E.g. Cyanobacteria (blue-green algae), crustose, grey, orange and yellow lichen and snails can survive here.

32. Adaptations • An adaptation is a feature of an organism that helps it survive in its particular environment – that is, live long enough to produce viable offspring. • Adaptations may be behavioural, structural or physiological.

33. Behavioural adaptations • Are observable activities/responses Examples: • Moving out of the sun into the shade • Migrating to avoid a cold winter • Huddling together for warmth

34. Structural Adaptations • Are anatomical features Examples: • Insulating layers of fur or fat • Presence of sweat glands in skin • Body shapes with differing SA:V ratios

35. Physiological Adaptations • Are those that relate to the way in which a living organism or body part functions Examples: • Increasing/decreasing metabolic rate • Dilation/constriction of arteries • Producing more red blood cells at altitude where O2 pressure is lower

36. Australian Environments • Terrestrial (land) and aquatic (fresh and saltwater) environments. Australian terrestrial environments vary due to climate and latitude: • Northern latitudes are tropical • high summer and year-round rainfall, high humidity • tropical rainforests along coasts

37. Inland are semi-arid to desert: • low rainfall, extreme high and low temperatures, low humidity • semi-arid  desert • sparse vegetation • Southern latitudes are temperate • moderate rainfall and humidity, average temperatures with some extremes • snowfall in areas high above sea level and parts of Tasmania • four season climatic pattern

38. Australian Environments (cont..) • Australian soils are nutrient deficient because they are old and weathered. • Marine environments are ecologically diverse. • Some freshwater sources may dry up in summer or in drought.

39. Vegetation Types Australian vegetation can be classified according to: • The type of plant that forms the dominant layer. • Density or canopy cover – Estimated based on the amount of sunlight blocked out. • Open forests – less than 30% • Closed forests – more than 70%

42. Distribution of Australian vegetation types

43. Surviving in the Australian Environment • Deserts are distinguished by very low rainfall compared with high water loss through evaporation. • They can be hot or cold deserts. • Australia has the greatest percentage area of desert of any continent. • Australian deserts generally have high temperatures and sunlight and low rainfall.

44. Plants in arid environments Adaptations for reducing water loss • Xerophytes (‘lovers of dryness’) • are adapted to living in dry conditions • leaves avoid water loss and increase in internal heat • Include succulents and sclerophylls (hard leaved) plants • Sclerophylls leaves: • thick waxy coating • hairs covering stomata • reduced leaf surface area to volume ratio • orientation of leaves away from suns rays

45. Leaf cuticles and hairs • A thick cuticle (waxy outer layer) reduces water loss by reducing diffusion through the epidermis. • Leaf hairs reduce water loss and surface temperature by creating a still layer of air along the leaf surface decreasing the water concentration gradient between the air and the leaf.

47. Distribution of stomata • Fewer stomata which are often in sunken in grooves or pits close during the hottest part of the day to reduce water loss. Reduced surface area and leaf orientation • Thin to needle-like leaves (e.g. Hakea). • Eucalypt leaves hang vertically downwards and are orientated so that the edge of the leaf faces the midday sun. They are isobilateral because they have stomata and photosynthetic cells on both sides of the leaf.

48. Halophyte adaptations • Halophytes (‘lovers of salt’) • Tolerant of high salt levels • Usually succulents • Coastal ecologies • Water loss through transpiration causes salt to transported from the roots to the leaf. Excess salt causes loss of turgor, stomatal closure and reduction in transpiration and CO2 uptake.

49. Physiological adaptations and surviving salinity • Salt tolerant plants regulate salt levels by controlling salt absorption and isolating salt within the shoot. • Physiological adaptations: • Higher osmotic pressure in cytoplasm • Exclusion of salt from leaves • Return of salt to roots • Dilution of salt by increased shoot growth • Shedding salt-laden leaves • Excretion of salt from salt glands

50. Australian fauna: Survival in the desert • The three main challenges for Australian desert animals are body temperature, water and salt balance. • Temperature regulation in desert animals can be assisted by: • Behaviour which increases or decreases heat exchange with the environment • Changes in circulation of blood in the skin effecting the rate of heat exchange • Increased or decreased production of metabolic heat • Evaporative cooling through panting or sweating (can also be a problem)