mod 3.1 - effects of the environment on organisms

Question 1

What are individuals?

Answer 1

A single organism.

Question 2

What is a population?

Answer 2

A group of organisms of the same species, living together in a defined geographical area. Eg: fruit bats in colony

Question 3

What are communities?

Answer 3

An ecological grouping of different species that live together and interact. Eg: the flying fox, birds and Bennett’s tree kangaroo rely on the Queensland umbrella tree for it’s nectar → this interaction will consider these species as being community

Question 4

What are ecosystems?

Answer 4

An ecosystem is a system formed by communities of organisms interacting with one another and their physical surroundings.
To be called an ecosystem it must be self-sustaining.
There are aquatic and terrestrial ecosystems.

Question 5

What are ecosystems made up of?

Answer 5

An ecosystem is made up of environments; environments are not ecosystems, as environments only describe an organism’s physical surroundings, not it’s interactions.
Made up of biotic (living) and abiotic (non-living) factors.

Question 6

What can ecosystems vary in?

Answer 6

Vary in size.
Vary in complexity.
Be found within an ecosystem. Eg: rock pools are a part of the larger marine ecosystem, but can be studied individually as small ecosystems.

Question 7

What are biomes?

Answer 7

A biome is a group of communities that have similar structures and habitats extending over a large area.

Question 8

What is a desert biome?

Answer 8

Desert: low rainfall, high light intensity, lack of tall plants, can be both warm/cold (Antarctica vs. Sahara → based on geographical location), dry because of little precipitation.

Question 9

What is a grassland biome?

Answer 9

Grassland: found on both sides of equator, contains shrubs and isolated trees, not much precipitation (but enough to sustain vegetation), topography: prairies, rocks, cliffs, gullies, temperature ranges relative to seasons.

Question 10

What is a shrubland biome?

Answer 10

Shrubland: hot and dry summers, mild and moist winds, nutrient poor soil (low-lying plants that are adapted to drought), high winds.

Question 11

What is a woodland biome?

Answer 11

Woodland: hot and dry summers, nutrient poor soil and prone to fires (similar to shrubland).

Question 12

What are temperate forests?

Answer 12

Temperate forest: mostly located alongside water with warm currents, temperate temperatures (never below freezing or too hot), consists of gullies and wetlands, acidic soil.

Question 13

What are tropical forests?

Answer 13

Tropical forest: high rainfall due to close proximity to oceans with warm currents and the equator, humidity and warm temperatures with a wet and dry season, soil with many nutrients.

Question 14

What is the biosphere?

Answer 14

The largest and most complex ecosystem is the biosphere, which is the cum of all ecosystems on Earth.
It includes all parts of Earth that are inhabited by organisms, including those in the lithosphere, the hydrosphere and the atmosphere.

Question 15

What are selection pressures?

Answer 15

Selection pressures are all the biotic and abiotic factors in an organism’s environment that affect the individual’s behaviour, survival and reproduction.
Selection pressures involve limiting a resource (usually).
Adaptations occur from these selection pressures (such as cold temperatures, excess salinity, lack of water and the threat of predators).

Question 16

What is a species?

Answer 16

Species: an organism that can mate with another organism and produce viable offspring (offspring that can go on further to reproduce).

Question 17

What is abundance?

Answer 17

Abundance: the amount.

Question 18

What is the distribution?

Answer 18

Distribution: how and where they are located.

Question 19

What affects the abundance and distribution of a species?

Answer 19

Biotic and abiotic factors will affect the abundance and distribution of a species.

Question 20

What are some abiotic selection pressures?

Answer 20

Light, temperature, weather, water, shelter, topography, chemical components.

Question 21

Give eg of light:

Answer 21

Affects plant’s root growth, leaf expansion and determines pigment systems (chlorophyll, phytochrome).
In animals, light affects growth, colouration, migration, reproduction, metabolism and circadian rhythms. Eg: humans and other diurnal animals are most active during the day and nocturnal animals like possums are the opposite. This is in relation to light conditions and circadian rhythms.

Question 22

Give eg of temperature in animals:

Answer 22

Dormancy occurs when temperature is not favourable.
Some animals, like birds, can only exhibit short-term dormancy, known as daily torpor, where their body temperatures drop at night in cold temperatures, and other animals, like black bears, go through sustained dormancy or hibernation, where they can drop their metabolic rate for months during the coldest times of the year. Arctic ground squirrels also go into hibernation, where they lower their body temperature to sub-zero (only warm-blooded mammals possess this ability).

Question 23

Give eg of temperature in plants:

Answer 23

In plants, the hormone abscisic acid is responsible for the establishment and maintenance of dormancy.
Boreal plant species (plants adapted to subarctic regions in the Northern Hemisphere) exhibit bud dormancy during winter months, where growth is not favourable.
Temperature also affects germination of seeds, eg: Australian banksia requires 500 degree temperatures for at least two minutes to be able to melt the resin on it’s pods to release seeds for germination.

Question 24

Give eg in weather:

Answer 24

Leaves will wilt with low rainfall and high temperatures.
Birds are able to predict changes in weather by detecting change in air pressure, which changes their flight patterns and feeding.

Question 25

Water in different aquatic environments:

Answer 25

Freshwater environment:
Temperature variation (particularly sensitive).
Dissolved gases.
pH - must be neutral.
Light availability.
Turbidity (clearness): important.

Saltwater/marine environment:
Salinity.
Dissolved gases.
Temperature variation.
pH - less important, can be acidic.
Light availability.
Turbidity.

Question 26

Give eg of shelter:

Answer 26

Provides protection from weather and predators, while providing space for growth, development and socialisation.
Mainly abiotic (wombat in burrow) but can also be biotic (tree providing shade for lion).

Question 27

What is topography?

Answer 27

Topography is the shape of the land, and affects water runoff and soil type.

Question 28

What is aspect?

Answer 28

Aspect (direction a slope faces) causes variation in the amount of sunlight received by an area of land. (Southern Hemisphere: slopes with a southerly aspect generally have colder conditions and harsher winds.

Question 29

Other factors that affect topography?

Answer 29

Altitude: higher above sea level = air pressure, oxygen availability and temperature decrease.
Soil: component of terrestrial landscapes that are important for exchange of gases, nutrients and water and for structural support for plants. Soil formation, type and quality are determined by the topography.

Question 30

Factors of chemical components:

Answer 30

Include trace elements, heavy metals and pH.
Biogeochemical cycles.

Abiotic factors determine the distribution of organisms: where organisms can survive and reproduce.

Question 31

What is organism tolerance?

Answer 31

Tolerance is an organism’s ability to survive within the physical conditions of an environment. Each organism has a tolerance range, a range of conditions in which it can survive.

Question 32

What are wide tolerance ranges?

Answer 32

Wide tolerance ranges have wide distribution: tend to be bacteria, eg: Salmonella genus can survive between 5.2-46.2 degrees celsius.

Question 33

What are narrow tolerance ranges?

Answer 33

Narrow tolerance ranges have narrow distribution: eg: photosynthetic algae, zooxanthellae is limited to shallow tropical and subtropical waters and have an optimum range of 16-18 degrees celsius.

Question 34

How have humans affected abiotic factors?

Answer 34

Humans have caused climate change, thinning of the ozone layer and decreased sunlight penetration, erosion etc.
Humans, through pollution have altered the abiotic selection pressures already present, as well as introducing new pressures. Eg: increased CO2 in the atmosphere has seen a rise in temperatures and exaggerated selection pressures on the corals of the Great Barrier Reef, putting stress on corals. Zooxanthellae gives coral it’s colour, and because humans cause an increase in global temperature, corals are forced to eject zooxanthellae and coral loses its colour → coral bleaching.

Question 35

What are biotic selection pressures?

Answer 35

Includes the availability of food, competition, availability of mates, amount of predators, invasive species, presence of diseased throughout ecosystems.
Balance of ecosystems will rejuvenate after a negative selection pressure and adapt as they need to.

Question 36

Give eg of habitats?

Answer 36

Some organisms only have one habitat: Victoria’s snow daisies are only found in the mountains of the Snowy Range.
Other organisms live in a greater range of habitats: Australian flying foxes live in forests, paperbark swamps and mangroves from QLD - VIC.
Some organisms move from habitat to the other based on seasons: pelicans move inland from coasts to take advantage of wetlands that form during times of rain and flood.

Question 37

What are microhabitats?

Answer 37

Microhabitat: habitats in smaller areas; eg burrow, tree canopy or even the inside of another organism.

Question 38

What happens when one species changes?

Answer 38

A change to one species affects other species and sometimes the entire ecosystem. This is because species are interconnected in ways like food webs, which provide stability in an ecosystem. One species lost drastically affects the food web.

Question 39

What is a keystone species? give eg

Answer 39

A species that plays a critical role in maintaining the structure of an ecosystem, and when removed instability occurs.
Keystone species maintain both the biodiversity and abundance of a species.
EG: When the carnivorous sea star Pisaster ochraceus was the top predator in rock pools; and when removed, there was a population explosion of the barnacles and mussels, resulting in it’s food sources (algae) to decrease, along with it the limpets, as limpets also ate algae. Because of these significant changes in the ecosystem from the removal of this sea star, the sea star is a keystone species.
Some keystone species are keystone species because they maintain important habitats within an ecosystem.
Elephants preserve the grasslands of African savannas by eating young trees, without them, savannas would be invaded by trees and shrubs, and grazing herbivores would die.

Question 40

How do humans affect abiotic selection pressures?

Answer 40

Human activities also add to selection pressures, both directly and indirectly.
Humans remove animals from ecosystems through pollution, hunting and more, causing an imbalance in an ecosystem (fishing).
Can also directly place selection pressures on organisms through processes such as artificial selection: selectively breeding organisms with specific traits to increase the number of offspring with these desired traits.
Humans can affect keystone species which is extremely detrimental to the ecosystem balance, such as seen in the culling of grey wolves from Yellowstone National Park, originally seen as a pest, but their eradication resulted in an increase in the elk population which overgrazed the aspen and willow plants, which led to a loss of habitat for smaller species like beavers and songbirds, as well as stream bank erosion and water sedimentation.

Question 41

What is ecology?

Answer 41

The study of interrelationships between different types of organisms, in their environment.
Looking at the distribution and abundance, population and biodiversity. (species can be randomly, uniformly or clumped in distribution).

Question 42

What are quadrats?

Answer 42

Used for stationary/slow moving organisms.
A metre x a metre square made of pvc pipes.
The amount of an organism of population cover percentage is estimated.
Multiple quadrats are taken, and by finding the average of a species and multiplying the mean by the area of the whole study, an estimation of the population size is made.

Question 43

What is capture-recapture/capture-tag-recapture?

Answer 43

Used for mobile organisms, tagged by chalk or nail polish.

More captures = more reliable.

Question 44

What is trap and count?

Answer 44

Uh, pretty self-explanatory.

Used for slow moving organisms.

Question 45

What is an unmanned aerial vehicle?

Answer 45

Best way to estimate using drones; take pictures and count.

Question 46

What is a transect line?

Answer 46

Consists of a tape measure and at each set interval, record what it touches; used for non-moving organisms.
Normally done on a slope.
Have diagrams with keys.
Gives a general picture of what the ecosystem looks like.

Question 47

How is population growth affected?

Answer 47

Can be affected by 4 processes (as a result of biotic and abiotic factors)
Births or germination or natality
Deaths or mortality
Immigration (organisms moving into a population)
Emigration (organisms moving out of a population) (with immigration is collectively known as migration).

Question 48

What is exponential population growth?

Answer 48

When populations are not limited by resources, predators or disease, they experience continual, unlimited growth, known as exponential growth. Individuals continue to reproduce regardless of population size and the rate of population growth, until it is limited by the carrying capacity of the environment.

Question 49

What is the theoretical exponential growth?

Answer 49

Ecologists use mathematical formulae to model the theoretical growth of a population over time. As long as the birth rate is higher than the death rate, a population will grow, and if this birth rate remains consistently higher, then the population may grow exponentially.

Question 50

When do species undergo exponential population growth?

Answer 50

Species that tend to experience exponential population growth are those that have a short generation time and give rise to large numbers of offspring; eg: bacteria, weeds and insects.
Some species experience exponential growth during certain periods of their lifecycle, eg: sea turtles bury a large amount of eggs, which when hatched, increase the population exponentially, however, only few babies survive making it safe to the water, resulting in the population to decrease again.

Question 51

What is the prickly pear cactus?

Answer 51

Prickly pear cacti are of the genus Opuntia and family Cactaceae and are native to the Americas. It thrives in warmer ecosystems because they have developed adaptations that allow them to hold a high water content to survive harsh weather conditions such as drought.

Question 52

Why are prickly pear cacti here and where did they come from?

Answer 52

The species were introduced to Australia in 1788 to start a cochineal dye industry. From here, it invaded the landscape and became wild weeds, and were completely out of control by 1920.
They were spread from NSW to QLD through using it as a garden plant. It’s uses included growing food and providing cochineal dye, and this spread of the plant allowed it to invade the majority of Australia.
Because the dry, Australian climate was similar to that of the Americas, the prickly pear was able to thrive. By 1920, the prickly pear had overtaken 60 million acres of land, and was estimated to be spreading over one million acres per year.

Question 53

What is the impact prickly pear cactus are having on the ecosystems?

Answer 53

Because of its rapid growth, the prickly pear interfered in the growth of native vegetation. Restricted to a certain size, natives were killed off from the mass invasion of the prickly pear.
Also, from its spines (found on most cacti; the sharp hair) causes injury amongst native species; their invasion leading to the forced migration and displacement of certain species.
This overall invasion of the prickly pear kills and/or forces species to migrate, interfering with the natural flow of the ecosystem. Ecological niches are abandoned, the food chain becomes unbalanced and the biodiversity within the ecosystem becomes minimal.

Question 54

What are the cane toads?

Answer 54

Cane toads are amphibians that are Native to South and Central America. Their diet consists predominantly of insects. They have dry brown-yellow-grey skin and usually grow to 15 cm in length.

Question 55

Why are cane toads here and where did they come from?

Answer 55

They were introduced into Australia from Hawaii in 1935 as a biological control in order to control the cane beetle population that was feeding off sugarcane, however this did not work because the cane toad could not jump high enough to reach the beetles.

Question 56

What is the impact cane toads are having on the ecosystems?

Answer 56

Their rapid dispersal from their rapid reproduction resulted in them invading the whole of Australia, especially in QLD. Female cane toads can lay 8000-30000 eggs at a time, and they hatch in just 2-3 days.
They also became highly adapted to the various environments in Australia, from deserts to rainforests. They also had no predators or any other risks like infection, so they are able to thrive while living comfortably at the same time.
Cane toads affect all native species with their poisonous glands. Native predators like kookaburras, quolls and goannas die after ingesting the cane toad. They also compete for habitat and food sources; their high populations depleting these things.