Module 4: Ecosystem Dynamics Part 1

Relative density i (Rdi) Percentage Coverage (C) Relative coverage Diversity

Relative density i (Rdi) The Density of species i, Di, Divided by the sum of all the densities of the other species sampled Rdi=Di/S D Eg. 10/5+8+16 Percentage Coverage (C) The proportion of ground that is occupied or area covered by the plant/species C=a/A x100 a=the area covered by species i A=the total area Relative coverage The Coverage of species 1, Ci, divided by the sum total of the coverage of the other species sampled Diversity The measure of variety of an ecosystem Consists of 2 components The number of different species or the richness of species in a specific area The relative abundance of the individuals of each species in a specific area

Predator-prey populations

- The relationship between a predator and prey is that predators eat prey. Predators influence the death rate, birth rate and survival rate of their prey. The predator cycle follows the prey cycle - as number of prey increase, there is a more food for the predaotr so the numbers of predators increase. - The woolly aphid was a particular pest in apple orchards. A north American wasp was introduced that was successful at eating and wiping out a whole colony of aphids. However, some aphids usually escape and move into the roots, whwere they surviv but where the wasps never reach. Thus. There are always some of both species present. - It is detrimental for a predator to be totally efficient at catching prey in order to control the overcrowding population of prey. This maintains the predator-prey cycle. - When ecologists interpret predator-prey cycles, they must also considerother variables such as migration, climate changes and other species. - More predators mean less prey can survive and so the numbers of prey begin to decrease. Now there is less food so the numbers of predators decrerase which means more prey will survive and prey numbers increase again. Thus the cycle continues.

Factors affecting the distribution and abundance of animals

1. Biotic factors relate to other living things in the area. E.g. the distribution of a species may relate strongly to where it can find food. Abundance of a species may be affected by the abundance of its food source 2. Abiotic factors relate to the non living environment e.g. each species has its preferred temperature range and may not be able to live in certain areas because it is too hot or too cold. 3. Presence of other species: the other species may be the food of the organism being considered or it may be a predator on it. The other species may compete for some of the available resources e.g. food, shelter, nesting sites, etc. sometimes the other species may have a mutualistic relationship with the organism. E.g. bees are important pollinators and the species may not be able to reproduce as abundantly if bees are absent. 4. Oxygen. Oxygen is abundant on land (20%) but it is relatively scarce in water (less than 1%). There is less oxygen in warm water than in cold water. There is less oxygen in deep water compared to surface waters. There is less oxygen in stagnant water than in running water. Bacteria in decaying matter use up the oxygen in water so that lakes with decaying reeds have very little oxygen. Many water creatures are limited as to where they live by the oxygen present. 5. Salt concentration. Animals which live in salt water tend to dehydrate due to the ovement of water out of their bodies by osmosis. Animals which live in fresh water tend to bloat due to movement of water into their bodies. Thus it is very difficult for an animal adapted to living in salt water to move into fresh water and vice versa. 6. Humidity. Many land organisms do not have an effective waterproof covering (e.g. frogs, earthworms, slaters) and must stay in areas of high humidity. 7. Water. Most of Australia has a very low rainfall and organisms face a critical shortage of water. Only animals which have special adaptions to help them survive can live in these areas.

Mark and Recapture Technique What is a sample? Why do we sample? Transects and Quadrants Samples taken at fixed intervals

A technique called sampling can be used to estimate population size. In this procedure, the organisms in a few small areas are counted and projected to the entire area. For instance, if a biologist counts 10 squirrels living in a 200-square foot area, she could predict that there are 100 squirrels living in a 2000 square foot area. This is a simple ratio. Mark and Recapture Technique In this procedure, biologists use traps to capture animals and mark them in some way. The animals are then returned unharmed to their environment. Over a period of time, the animals are trapped again, with researchers recording how many of the original tagged individuals are recaptured. The ratio of animals trapped with the tags and the animals trapped that were not tagged is used to estimate the overall population number. Making quadrats reliable = more quadrats Reliable = bigger sample area, conditions, repeating What is a sample? "A portion, piece, or segment that is representative of a whole" Why do we sample? it is usually impossible to measure the whole That the sample is representative of the whole It is necessary to take enough samples so that an accurate representation is obtained It is important to avoid bias when sampling Transects and Quadrants Plants and Non-motile animals Mark Release Recapture Small animals Aerial observations - e.g. use of a drone Large trees and animals Samples taken at fixed intervals Set up along an environmental gradient (e.g. high to low on a mountain)

Abiotic factors

Abiotic factors determine where an organism can or cannot live (their distribution) Biosphere is the part of earth that contains living things Every living thing exists within a framework of biotic and abiotic factors called an ecosystem

Abiotic

Abiotic: non-living: physical and chemical factors. E.g. temperature, rainfall, salinity • temperature • Water • Shelter • Nesting sites • Oxygen • Humidity • Salt concentration of water • Exposure to waves

Allelopathy

Allelopathy: The production of specific biomolecules by one plant that can be beneficial or detrimental to another plant (usually detrimental). Plants produce these biochemical (allelochemicals) which are released into the surrounding area to kill or inhibit growth of other plants competing for the resources in the same area. Examples: - Black walnut plant - releases a chemical from its buds and roots that inhibits respiration of other plants. Plants that are exposed to its allelochemicals will wilt, have its foliage turn yellow and eventually die. - Pine trees (some species) - when their needles fall to the ground they begin to decompose and release acid into the soil which keeps plants from growing there

Biotic

Biotic: organic matter, living: e.g. organism abundance, distribution and interaction • Availability of food • Competition with same or another species for: food, shelter • Number of predators • Prevalence of disease • Once living • Mutalistic relationships

• the ecological niches occupied by species

BIOME The biggest ecosystem is a biome: A biome is a large geographical area of distinctive plant and animal groups, which are adapted to that particular environment. The climate and geography of a region determines what type of biome can exist in that region. Major biomes include deserts, forests, grasslands, tundra, and several types of aquatic environments. Each biome consists of many ecosystems whose communities have adapted to the small differences in climate and the environment inside the biome. ECOSYSTEM A community of living organisms together with its environment; any environment containing organisms interacting with each other and the non-living parts of the environment. COMMUNITY An ecological community is a group of actually or potentially interacting species living in the same location. Communities are bound together by a shared environment and a network of influence each species has on the other. POPULATION - A group of individuals of the same species occupying a particular geographic area ORGANISM - A living thing HABITAT - Where an organism live. NICHE - An organism's job in an ecosystem. A niche describes the functional position of a species or population in an ecosystem.

Coevolution

Coevolution: occurs when species in an ecological relationship evolve in response to changes in each other. Coevolution can result from feeding relationships and/or symbiotic relationships

Commensalim

Commensalim Relationship where one species benefits and the other is unaffected i.e. the effect is neither positive or negative. Examples: - Epiphytes - grow upon or attach to a living plant. They only take physical support from plants, obtaining nutrients from the air and falling rain. E.g. certain specieis of ferns and mosses. - Barnacles - whales and turtles provide transportation for some species of barnacles. Also, barnacles are able to filter feed from ocean currents while they are travelling on whales. - Remora fish - have an adhesive disk on the surface of their heads which allows them to attach to the underside of sharkes or whales. This provides them with transport to other parts of the ocean and allows them to catch bits of food floating away from the mouths of sharks or whales.

Competitive exclusion principle Fundamental niches Realised niches

Competitive exclusion principle = is that no two species can occupy the same niche. Fundamental niches = range of possible environmental conditions suitable for the existence of a species Realised niches = the part species actually occupies at certain times

Consequences of Predation

Consequences of Predation Species - Prickly Pear and the Cactus Moth https://www.daf.qld.gov.au/__data/assets/pdf_file/0014/55301/IPA-Prickly-Pear-Story-PP62.pdf 1. Definition of your given relationship - Ruby • Predation affects the species in a way that one animal survives and another dies • A predator is an organism that eats another animal • The prey are organisms that are consumed by a predator • Examples of predators include lions, sharks, tigers, and polar bears. • Predation is a relationship where one organism acts as a predator who catches and consumes another organism that acts as prey 2. Description of how your given relationship affects the organisms in your ecosystem - Tia • Affects the distribution and abundance of their prey • The abundance of a predator and its prey can alternate through time, with the predator numbers copying those of the prey. • The abundance of food for the prey and other surrounding organisms that share similar resources will either decrease or increase depending on the amount of predators, influencing the amount of space taken up by organisms • E.g. the prickly pear grows at a rapid pace. This then takes up a lot of room due to the branches becoming easily detached and multiplying quickly. The cactus moth is able to control effectively in reducing the plant numbers. This ensured that there was room for other species of plants to grow. 3. The consequences of your given relationship to the ecosystem (both abiotic and biotic) - Tia • When there are large numbers of prey available, the population of the predator increases. • As prey numbers decline, there is a shortage of food for predators, which ultimately leads to the decline of the predator and the population of a particular species • Reproduction rates will increase • Size of an ecosystem - where organisms can live and be supported without overcrowding → competing for space • The movement between ecosystems will be needed, however, will be difficult to do as that would result in organisms experiencing trouble to adapt • E.g. the prickly pairs decline in population ensured that there was more free soil and that other species of plants could grow more in the same area. 4. Data and graphs to support how your particular relationship affects the distribution or abundance of organisms - Erin Prickly pear infestations covered 10 million acres of land by 1900 and 58 million acres by 1920. Management was put in place to try and slow the rate but it did not work and it was estimated that the plant's rate was 2.4 million acres per year. This heavily affected the abundance of other organisms living in the same environment. Predation causes predator species to be lower than the prey species and they lag in numbers behind them. As the prey species increases the predator species will increase after the prey. The prickly pear in this example is the prey and the cactus moth is the predator. The number of Cactus moths fluctuates in relation to their prey, the prickly pear. 5. What predictions you can make about the future of the ecosystem, both in the short term and the long term (the data in the graph should help you with this) - Ruby In the short term, numbers of prickly pear will continue to rise at high rates and continue to cover land. It will continue to act as a prey to the cactus moth because as prey rates increase, so do predator rates. In the long term, the rate of population may begin to slow down due to natural selection. More animals may start to adapt, making the prickly pear a food source to them due to the large abundance of prickly pears. Although if rates of populations are decreasing, so will predator rates if they are big enough. There will be more space made for other plants to grow because there won't be the competition of the prickly pear.

Consequences of Symbiosis

Consequences of Symbiosis Definition: Relationship between 2 organisms that live together in a close relationship which is either beneficial to both or at least one of them. Description: Symbiosis affects • There are 3 types which include Parasitism, Mutualism and commensalism • Commensalism: One organism benefits and the other is neither harmed nor helped. • Mutualism:Both organisms benefit. • Parasitism: One organism (the parasite) benefits and the other (the host) is harmed. • Has profound consequences for life which will be discussed Consequences Abiotic: Symbiosis necessary to keep the ecosystem functioning, if the organism are necessary for the ecosystem Biotic: increased evolutionary diversification - biodiversity, The development of new species from the integration of their genetic material with each other Predictions Short term: • Mutualism: Both species temporarily benefit from each other • Commensalism: One species benefits and the other one unaffected • Parasitism: Prevent imbalances in ecosystem caused by too many Long term: • Mutualism: Both species increase rapidly, impact the balance of ecosystem • Commensalism: One of the species increase rapidly, the other one normal increase • Parasitism: The hosts of parasitic decrease significantly Consequences of disease Definition: Any process that adversely affects the normal functioning of tissues in a living animal. This includes infectious and non-infectious Description: In regards to diseases the greatest threat to a wild ecosystem is infectious ones. These diseases in places like Australia for example, affect many native plants and animals and agricultural crops.There is usually a pool of disease causing agents or Pathogens ( Viruses, Fungi and Bacteria) already present in the environment. For the disease to break out however the Pathogens must be introduced into the new host population from where the disease spread through either direct or indirect means or its a selective change which causes a change in abiotic or biotic conditions. Some diseases have contributed to significant losses of species leading to some species becoming threatened or extinct.This is because it affects the health of native species, reducing their ability to reproduce or survive which leads to an array of consequences which will be discussed. Consequences Biotic: alter balance of food webs (affects predator and prey), dire consequences to humans as humans and a health of environment is related. Abiotic: Contamination in water/soil caused by pathogenic microorganisms. Predictions In the short term, there will be numerous individuals that gets infected by the disease, and eventually in the long term the population of affected species will suffer from a decline, for example the Tasmanian Devil. This disease caused the Tasmanian Devil to be visually impaired and difficulties in finding food. There is the possibility that they will go extinct 25 years after the outbreak. Justification The information are found in the textbook.

Consequences of competition

Consequences of competition Species - Two Grain Beetles 1. Definition of your given relationship - Ruby • Two or more species that compete for the same resources such as food, water and shelter within an environment • Resources ensure survival within an environment • Competition can be intraspecific (between the same species) or interspecific (between different species) 2. Description of how your given relationship affects the organisms in your ecosystem - Tia • This affects how species fight for resources and survival. • When two species compete for a resource, the short term effects is a decrease in population numbers both the prey and the competing species → As food sources decrease, so does the abundance of both competing species • E.g. the Calandra and Rhizopertha grain beetles have a distinct difference in size. It was observed that when the species were sharing the same environment, one species had a very low number (Rhizopertha) when competing for dry foods such as rice, wheat and oat. 3. The consequences of your given relationship to the ecosystem (both abiotic and biotic) - Tia • The consequences of competition between species for resources affect reproduction and survival rate. • The abundance of resources within the ecosystem. This could result in losing species in the area (even extinction) • Competition for space, water, food could result in a loss of availability and a change in the way organisms interact especially with the ecosystem • E.g. the competition for resources for the Calandra and Rhizopertha grain beetles will affect the population of each with the decline in one. This could ultimately lead to the increase of grain plants that grow in an ecosystem, resulting in the available space of an ecosystem to decrease 4. Data and graphs to support how your particular relationship affects the distribution or abundance of organisms - Erin Competition has a great effect on the distribution or abundance of organisms. As there are two or more species competing for the same resources, there usually is one species that outlives the other, like a running race (there can only be one winner). The two species a start at and even and fair level (like the start of a race). As time passes, one species gains an advantage over the second species and can gain all the resources they need for maximum survival. As this occurs the population of the advantageous species increases as they have access to their essentials. On the other hand the other species starts to struggle for survival and their population decreases as they lack in the essentials, because the surviving species has control on the resources. This leaves the second species lacking their needs causing the species to slowly die out, and the first species outliving, thriving and fluctuating in numbers. As the second species die out, the first species has more resources like food, which leads them to their success. 5. What predictions you can make about the future of the ecosystem, both in the short term and the long term (the data in the graph should help you with this)- Ruby • In the short term, there won't be much resources such as food and shelter because two of more species will be competing with each other in order to beat the other species. The species would be taking all the resources required for survival at a fast rate. • In the long term it is likely that only one species will survive because they had an advantage over the other/s. This means that they were able to outlive the other species and can continue to live and use the resources of the habitat they were originally in. The specie that outlived the others will continue to reproduce and pass on the advantageous trait to their offspring, increasing in population.

Consequences of disease

Consequences of disease Definition: Any process that adversely affects the normal functioning of tissues in a living animal. This includes infectious and non-infectious Description: In regards to diseases the greatest threat to a wild ecosystem is infectious ones. These diseases in places like Australia for example, affect many native plants and animals and agricultural crops.There is usually a pool of disease causing agents or Pathogens ( Viruses, Fungi and Bacteria) already present in the environment. For the disease to break out however the Pathogens must be introduced into the new host population from where the disease spread through either direct or indirect means or its a selective change which causes a change in abiotic or biotic conditions. Some diseases have contributed to significant losses of species leading to some species becoming threatened or extinct.This is because it affects the health of native species, reducing their ability to reproduce or survive which leads to an array of consequences which will be discussed. Consequences Biotic: alter balance of food webs (affects predator and prey), dire consequences to humans as humans and a health of environment is related. Abiotic: Contamination in water/soil caused by pathogenic microorganisms. Predictions In the short term, there will be numerous individuals that gets infected by the disease, and eventually in the long term the population of affected species will suffer from a decline, for example the Tasmanian Devil. This disease caused the Tasmanian Devil to be visually impaired and difficulties in finding food. There is the possibility that they will go extinct 25 years after the outbreak.

Distribution and abundance

Distribution and abundance Distribution refers to where an organism is found. In describing distribution use words like scattered, clumped, evenly distributed, on hill tops. Abundance refers to how many organisms are found in a particular aarea. In describing abundance use numbers rather descriptive words. E.g. 45 mangroves per 1000m2 Generally, in Australia, rainfall, temperature and landform patterns significantly affect the abundance and distribution of vegetation and ecosystems. Most of the rainforest ecosystems are distributed along the east coast of Australia, particularly in the northern regions. Just as important as the abiotic factors are the biotic factors that may influence an organism's existence in an ecosystem. Even though there is a much greater variation in biotic factors between ecosystems (e.g. availability of worms as a food source for kookaburras in one ecosystem may be much higher than for kookaburras in another), a few key factors will affect organisms within an ecosystem. Desert ecosystems, however, are distributed among the central areas of Australia. Abiotic factors such as a high temperature range and low rainfall (arid conditions) create an environment suitable for desert ecosystems. Of course, the distribution and abundance of organisms within these ecosystems may also vary due to biotic factors such as the availability of food, competition within and between species, the availability of mates for reproduction, exposure to predators, and exposure to disease. Ecologists also need to determine the distribution of organisms in order to look at any patterns that are formed and the possible reasons for this. This information enables us to determine whether a population is increasing or decreasing in size and what particular aspects of the habitat are favoured over others.

Exploring biomes Tropical rainforest: Temperate Forest: Deserts: Tundra: Taiga: Grasslands: Savannah: Freshwater: Marine:

Exploring biomes Often biologists group the different natural areas on Earth into categories based on plant and animal life and how they are able to survive in that part of the world. These are called biomes. Grouping organisms into biomes help us to better understand the complexity of life on Earth. Tropical rainforest: - moist warm air, wettest biome - Over half of all species are found in these - Close to equator - lowland, close to sea level - Lots of trees - tall - Birds (cock-of-the-rock), monkeys, leafcutter ants, frogs (poison dart) - Small-leaved tamarind ( fruit plants), rosy periwinkle, plant medicine Temperate Forest: - Trees are most abundant (Oaks, Maples, Ponderosa Pines or Douglas-Fir) - Canopies - Shade and sunlight for different trees - Changing seasons - Birds: Pileated Woodpecker, bears (brown or grizzly), deer - Fungi, insects (stick bugs - Shrubs such as gooseberry, orchids, mistletoe Deserts: - Not a lot of water, sometimes flash floods - Sand, dust - Extreme temperatures - Desert tortoise - Cactus (those that need to retain water longer) Tundra: - antarctic, alpine, and arctic - cold, dry weather - Imagine a scene by the mountain with sly rodents, birds, and large mammals moving about the area. - seals, birds, and many sea creatures survive there - Parry's primrose - Low shrubs, sedges, reindeer mosses, liverworts, and grasses. Four hundred varieties of flowers, such as crustose and foliose lichen, are also found in the arctic and subarctic. - Small creatures, such as ground squirrels, arctic fox - grayish-brown fur of snowshoe hare, arctic fox, and others like them blends into white hairs in preparation for winter camouflage. - Bears - Migratory birds such as falcons, loons, sandpipers, terns and snow birds Taiga: - Long Winters, short, humid summer - coniferous trees and even some deciduous trees - northern lights - garter snakes - snowshoe hare - wolves - great-gray owl - woog-frogs - white-throated sparrow - Siberian tiger - Not many plants can survive the extreme cold of the taiga winter. There are some lichens and mosses, but most plants are coniferous trees like pine, white spruce, hemlock and douglas fir. Coniferous trees are also known as evergreens. They have long, thin waxy needles. Grasslands: - largely empty of trees, receive less rainfall than savannas and endure broader temperature extremes. - Grass dominate temperate grasslands. Trees and large shrubs are rarely found in grassland areas. needlegrass, wild oats, foxtail, ryegrass, and buffalo grass. - grazing animals - zebras and antelopes, and the predators that prey on them, like lions and cheetahs. Savannah: - Grasses and trees - The savanna is a rolling grassland with scattered trees and shrubs. Rainy and dry seasons - Savannas have two distinct seasons in regards to precipitation. - The antelopes are especially diverse and include eland, impalas, gazelles oryx, gerenuk and kudu. Buffalo, wildebeest, plains zebra, rhinos, giraffes, elephants and warthogs are among other herbivores. Lions, leopards, cheetahs, jackals, wild dogs and hyenas. - The savanna is covered by grasses such as Rhodes grass, red oats grass, star grass, lemon grass, and some shrubs. Pine trees, palm trees, and acacia trees Freshwater: - Made up of any of body of water that is made of freshwater such as lakes, ponds, streams, and rivers. - cover roughly 20% of the Earth and are in various locations spread out all over the world. - Insects, to amphibians, reptiles, fish, birds and even mammals. Turtles, ducks, otters, crocodiles, catfish, dragonfly and crabs. - Water lilies, algae, and duckweed float on the surface. Mangroves and pickleweed. Marine: - Sea plants like marine algae, seagrasses, marsh grass, and mangroves provide habitats for many marine creatures including shrimp, bivalves, fish, plankton, and other small organisms.. - Fish - Sharks, swordfish, tuna, clown fish, grouper, stingray, flatfish, eels, rockfish, seahorse, sunfish mola, and gars. Marine mammals - Blue whales, seals, walruses, dolphins, manatees, and otters. - Water/sea, sunlight is important for plants and animals under water - 71% of planet - Coastal marine biome and an open ocean marine biome - The coastal biome (which is also called the coast) is found near the shores, beaches, and sea cliffs - The open ocean stretches from the edges of the coast between the continents for hundreds of miles.

MRSGREN

Factors affecting the distribution and abundance of animals M - movement R - respires S - stimulus C - cells G - growth R - reproduce E - energy N - nutrients

Foundation words in ecology: Ecosystem Dynamic Biodiversity Population Community Species Niche Consequence Impact Human activity Selection pressure

Foundation words in ecology. *make sure your definitions are relevant to ecology. Ecosystem A community together with its environment. Any environment containing organisms interacting with each other and with the non-living parts of an envirinoment. E.g. rainforests Dynamic The properties which stimulate growth, development or change within an ecosystem or processes Biodiversity The number, relative abundance and genetic diversity of organisms in an area or on earth Population A group of organisms of the same species living in the same area at a particular time Community The combination of groups of different populations in an area or habitat Species A group of organisms of similar appearance within a population, the members of which can interbreed to produce fertile offspring. Niche The place of a species within a community involving relationships with other species Consequence A result or effect on an environment Impact The effect that something has on living beings and on-living conevironment. E.g. natural disasters, greenhouse gas emissions Human activity Human impact on the environment including changes to biophysical environments and ecosystems, biodiversity and natural resources Selection pressure A factor, often in the environment, that affects the survival and reproduction of an individual within a population (usually by acting on a variation)

How understanding of allelopathic relationships would benefit people in agricultural industry

How understanding of allelopathic relationships would benefit people in agricultural industry = ensure that crops and other plants can grow in an environment that will have a decrease in the growth of weeds and other plants for maximum production and health

IQ2.1 A recent extinction event AUSTRALIA'S MEGAFAUNA

IQ2.1 A recent extinction event AUSTRALIA'S MEGAFAUNA - extinction even is a rapid and widespread decrease in biological diversity, this means a sharp change in the abundance and distribution of multicellular organisms. Species that fail to adapt to environmental changes or to compete for limited resources die out. This loss of a species or groups of species is called extinction - Mass extinction = these are evident in the fossil records. They are large scale extinctions following disruptions to the global climate or loss of sea or land due to shifting continents. Megafauna are large animals, such as elephants and whales. In the past there were more types present. Over the past 50 000 years most of the world's megafauna have become extinct. Two theories exist about this occurrence. It is likely that the extinction of Australia's megafauna is the result of both theories. 1. Climatic change- End of Ice Age, in the Pleistocene. In Australia the climate changed from cold and dry to warm and dry. Water became scarce. 2. Human Expansion - Extinction of many of Australia's megafauna occurred around the time that humans arrived on the continent. The arrival of skilled hunters combined with the fact that the megafauna were big and slow led to their extinction. Australia today contains many smaller relatives of these megafauna. Fossil records, especially of marsupials, show a decline in size since the late Pleistocene. Eg. Eastern Grey Kangaroo (Macropus giganteus) and the Red Kangaroo (Macropus rufus). Both are up to 30% smaller than their megafauna ancestors. Some examples of extinct Australian Megafauna are: - Phascolarctos stirtoni Giant Koala - Kambara implexidens Tingamarra swamp crocodile - Obdurodon dicksoni Riversleigh platypus The extinction of megafauna around the world was probably due to environmental and ecological factors. It was almost completed by the end of the last ice age. It is believed that megafauna initially came into existence in response to glacial conditions and became extinct with the onset of warmer climates. Tropical and subtropical areas have experienced less radical climatic change. The most dramatic of these changes was the transformation of a vast area of north Africa into the world's largest desert. Significantly, Africa escaped major faunal extinction as did tropical and sub-tropical Asia. The Asian elephant survives until the present day, while the Asian rhinoceros survives even on the relatively small island of Java, Indonesia. At the end of the last ice age, Australia's climate changed from cold-dry to warm-dry. As a result, surface water became scarce. Most inland lakes became completely dry or dry in the warmer seasons. Most large, predominantly browsing animals lost their habitat and retreated to a narrow band in eastern Australia, where there was permanent water and better vegetation. The diprotodon, one of Australia's megafauna, may have survived on the Liverpool Plains of New South Wales until about 7000 years ago. If people have been in Australia for up to 60 000 years, then megafauna must have co-existed with humans for at least 30 000 years. Regularly hunted modern kangaroos survived not only 10 000 years of Aboriginal hunting, but also an onslaught of commercial shooters. Worldwide, there is no evidence of Indigenous peoples systematically hunting nor over-killing megafauna. The largest regularly hunted animal was bison in North America and Eurasia, yet it survived for about 10,000 years until the early 20th century. For social, spiritual and economic reasons, First Nations peoples harvested game in a sustainable manner. Changes in climate: - Continent dried out due to ice age - Rainforests were contracting due to drying climate - Climate became hotter and drier, fires broke out ¬large animals were dependent of amply supply of water - died, couldn't adapt to change in environment Against: last ice age, before peak of ice age, climate change today does not seem to select lare, slow-moving species Arrival of humans: - Increased fires, 'fire-stick' farming burning the vegetation more available for hunting (slower) Increased fires meant more carbon deposit in fossils No fossil evidence of kill sites and little evidence of humans coexisting, an overlap in the size of the smallest extinct species and that of the largest present-day species Level of nutrients low levels of nutrients in the soil that cause nutrietion depletion throughout the food web, resulting in smaller animals - Fossil evidence has been found of the coexistence of humans and megafauna

Level of organisation

Level of organisation is used to show how organisms interact with each other and their environment A niche comprises: - the habitat in which the organism lives - the organisms activity pattern: the periods of time during which it is active - the resources it obtains from the habitat often bbiologists group the different natural areas on earth into categories based on plant and animal life and how they are able to urvive in that part of the world. These are called biomes. Grouping organisms into biomes help us to better understand the complexity of life on earth.

Light Quantity: Light Quantity: a) How is the factor measured and what units are used? b) What causes this factor to change? c) How does this change effect the organisms that live in the ecosystem?

Light Quantity: a) How is the factor measured and what units are used? Light quantity is measured using a photometer. It is usually measured by the units lux (lx) and footcandle (fc). One footcandle means the degree of illumination 1 foot away from a lighted standardised wax candle. Lux is the unit of illumination that a surface receives one meter away from a light source. b) What causes this factor to change? The quantity of light can change with the time of the day, season, geographic location, distance from the equator and weather. The quantity gradually increases from sunrise to the middle of the day and then gradually decreases toward sunset. The quantity of light is high during summer, moderate in spring and autumn and low during winter time. c) How does this change effect the organisms that live in the ecosystem? The change in light quantity affects living organisms as light is the requirement for plant growth and development. An increase in the quantity of light will result to an increase in the rate of photosynthesis and a decrease in quantity will reduce the number of hours that the plant must receive every day. Deficient light intensities tend to reduce plant growth. Photosynthesis significantly slows down while respiration continues which as a result will affect every other living organism that requires food form autotrophs. Excessive light intensity can scorch the leaves as it prompts rapid transpiration and water loss. The rate of photosynthesis decreases while respiration continues, resulting to low availability of carbohydrates for growth.

Line transect method Belt transect method

Line transect method A measured line laid across the area in the direction of the environmental gradient All species touching the line are be recorded along the whole length of the line or at specific points along the line Measures presence or absence of species Belt transect method Transect line is laid out and a quadrant is placed at each survey interval Samples are identified and abundance is estimated Animals are collected For plants an percent coverage is estimated Data collection should be completed by an individual as estimates can vary person to person

Measuring distribution Measuring abundance

Measuring distribution A transect line is often used to measure distribution. A rope, marked off in intervals, is stretched across the ecosystem and the presence of particular organism is noted and marked on a profile diagram. Transects provide an accurate and easy method of representing an area simply. Two examples of transects are:A plan sketch is an aerial or surface view of a representative area within an ecosystem. It shows to scale the distribution of organisms in a measured and plotted viewA profile sketch is a side-on view of an area showing to scale the distribution of organisms along a lineasd Measuring abundance 6. Using quadrants - if the organism is stationary, random quadrats may be placed throughout the ecosystem and the numbers counted in each quadrat. A quadrat is simply a sqare - it might be a small wooden frame or a large roped off area. Numbers of the organism being investigated is counted in each quadrat. The results are added and divided by the number of quadrats to find the average number in a given area. 7. Using capture-mark-recapture method - for obvious reasons quadrats cant be used for mobile populations such as birds and rabbits. An estimate of the population size is made using the following steps. o Capture a number of individuals (use traps) (S1) o Mark them in some ways (tags, paint) o Release them back into the wild population o Give them time to mix o Recapture a sample (S2) o See how many of the second sample are tagged (t) o Use the formula to estimate the size of the population S1xS2/t = size of population

Measuring populations of organisms using sampling techniques

Measuring populations of organisms using sampling techniques Distribution of a species can be defined as all the places in which it is found. A population will continue to grow in abundance until it is restricted by a limiting factor. A limiting factor is a resource that is in short supply and so restricts the growth of a population. Limiting factors include: lack of space, predators, disease, competition for food between members of the same or other species and physical factors. Resources can be abiotic and biotic. Example: whether conditions, availability of water and light etc. The distribution of plants in a marine environment is limited to the area where light penetrates for photosynthesis to occur. A POPULATION is a group of similar organisms living in a given area at the same time. By measuring the populations in a chosen area, you will essentially be determining the distribution (where) and the abundance (how many) of a species.

Mutualism

Mutualism: Where two different species benefit from living together. Some strong relationships mean that the survival of one member is impossible without the other. Examples: - Cleaner fish - remove and eat parasites from the larger fishes gills and mouthers - Bees and flowers - while collecting pollen from flowers, bees assist in seed dispersal, but they can benefit by making honey from pollen - Lichens - an algae and fungi living and working together as one organism. The algae produces food through photosynthesis whilst the fungus surrounds the algal cells and absorbs minerals and water essential for the survival of both species. An example of a mutualistic relationship between humans and other organisms = there are several kinds of bacteria (microflora) that live on the skin and inside the mouth, nose, throat, and intestines of humans and animals. These bacteria receive a place to live and feed while keeping other harmful microbes from taking up residence. Bacteria in the digestive system assist in nutrient metabolism, vitamin production, and waste processing. They also aid in the host's immune system response to pathogenic bacteria. Most of the bacteria that reside within humans are either mutual or commensal.

Niche Differentiation Why intraspecific competition is more intense:

Niche Differentiation Competition is most intense between members of the same species because their habitat and resource requirements are identical. Inter specific competition (between different species) is often less intense. Species with similar ecological requirements may reduce competition by exploiting micro habitats within the ecosystem. In the eucalyptus forest below different bird species exploit tree trunks, leaf litter, different levels within the canopy, and air space. Competition may also be reduced by e plotting the same resources at a different time of the day or year. Why intraspecific competition is more intense: because individuals have the same niche so are competing for exactly the same resources

Parasitism

Parasitism The relationship where one species benefits and the other species is usually harmed. A parasite gains food and shelter by either living on the surface (ectoparasites) or internally (endoparasites) in a host organism. They feed upon the tissue or fluids of the host, but often don't kill it otherwise their food supply will be destroyed. Examples: - Headlice (ectoparasite) - lives on the human scalp and feeds exclusively on human blood - Tapeworms (emdoparasite) - live in the digestive tract of humans and can grow up to 12m long - Liver flukes (endoparasite) - cause anaemia and liver disease by sucking blood in the human liver - Mistletoe - take nutrients and water from the plants they grow on and produce structures which penetrate host tissue

Populations of organisms do not

Populations of organisms do not remain at a constant level within an ecosystem. Many factors may affect their numbers including the requirement of other species in the ecosystem eg symbiosis. When the same species is found in an ecosystem year after year in approximately the same numbers, scientists say the population is stable. Population numbers may also decline. Disease, predations and competitions from other species can all contribute to the decline and possible extinction of an organism. Loss of an organism can be detrimental to a whole ecosystem. Scientists use models such as multivariate graphs to easily visualise trends and enable them to make predictions about the future.

Quadrats Mark Release Recapture

Quadrats Used to measure coverage and abundance of plants or animals A grid of known size (e.g. 1m2) is laid out and all the organisms within each square are counted. The quadrat is laid down in multiple area's and then the results averaged. Advantages = easy and inexpensive in large populations, minial disturbance to the environment, determining the distribution of species along a transect Disadvantages = suited for plants and slow-moving animals Mark Release Recapture Animals are captured,counted, tagged and released. After a period of time another capture occurs. Previously tagged animals are counted and unmarked organisms are marked. Advantages = simple that provies abundance for animals in large populations that are difficult to count Disadvantages = mobile animals, time consuming - type of species, method of tagging, disturbing to environment Abundance is calculated using the following formula: n1 x n2/ n3 n1=total marked after catch 1 n2=total marked after catch 2 n3=total caught in catch 2 but marked in catch 1 Measurements The number of individuals per unit area D=ni/A Eg. 10 dandelions/m2 ni=number of individuals for species i A=the area sampled (could be the volume V)

Predator-prey relationship:

Predator-prey relationship: - Greater numbers of prey - Shape falls behind of predater prey determines population of predator Pattern of graphs: prey has greater population, similar patterns in shape nad distribution Lag in predator population and prey = food source and/or competition with less of a population in predators Factors that affect the numbers of predator and prey populations = prey an predator: ecosystem, availability of resoruces, other species (competition and mutualism), environment e.g. temperature, predators, shelter Available resources = food for survival (prey), whether or not they need to compete Other species e.g. competition and mutualism = the ability to live together and share resources, shelter, etc. OR having to survive by being the first to food/nesting sites Temperature = whether an organism can survive in an environment for adequate metabolic functions Predators = the number will determine the population of what is a resource and what survives Shelter = available for surviving when need to sleep and escape other biotic or abiotic factors. Ee.g. predators, temperature

IQ1.2 Explain a recent extinction event

Researchers believe they have discovered what killed off mainland populations of the Tasmanian tiger — and their cause of death might surprise you. Associate Professor Jeremy Austin from the University of Adelaide has been comparing the genetics of mainland and Tasmanian thylacines for 10 years. Tasmanian thylacines survived until 1936, but mainland thylacines were last recorded in Aboriginal cave art dating back to middle Palaeolithic times. However, Dr Austin's radio carbon dating of thylacine bones revealed pockets of the species survived until 3,000 to 8,000 years ago in southern parts of Australia. So what killed them? Three theories have previously been prominent: • The introduction of dingoes to mainland Australia approximately 4,000 years ago; • A possible change in Aboriginal hunting techniques pressuring the population; and, more recently • A rapid change in climatic conditions. Dr Austin's research, with the help of PhD student Lauren White, has confirmed the main cause of thylacine extinction was a dramatic change in mainland Australia's weather patterns. "About the same time as dingoes arrived and human populations intensified, we also had the onset of El Niño Southern Oscillation (ENSO)," he said. "The climate in Australia went from relatively stable to suddenly very unstable. "It's very clear that the [Tasmanian population] went through a population crash around the same time the species went extinct on the mainland. YOUTUBE: Last thylacine 'Benjamin' in captivity at Beaumaris Zoo Hobart in 1933 "The fact that those things happened around the same time suggests to us it must have been one thing in both of those populations. "The only thing that is common is climate change, because dingoes weren't in Tasmania and human intensification wasn't occurring. "Climate change started the decline, then something on the mainland — either dingoes or humans — pushed the species all the way to extinction." Dr Austin said DNA sampled from remains showed no evidence of contributing disease or bacterial infections. Ancient mitochondrial genomes reveal the demographic history and phylogeography of the extinct, enigmatic thylacine (Thylacinus cynocephalus) Authors The Tasmanian tiger, or thylacine, is an infamous example of a recent human-mediated extinction. Confined to the island of Tasmania in historical times, thylacines were hunted to extinction <150 years after European arrival. Thylacines were also once widespread across the Australian mainland, but became extinct there c. 3,200 years before present (BP). Very little is known about thylacine biology and population history; the cause of the thylacines extirpation from the mainland is still debated and the reasons for its survival in Tasmania into the 20th century are unclear. In this study, we investigate the thylacine's phylogeography and demographic history leading up to their extinction on both the mainland and Tasmania to gain insight into this enigmatic species. Location Southern Australia. Methods We generated 51 new thylacine mitochondrial DNA (mtDNA) genome sequences from sub-fossil remains and historical museum specimens, and analysed them to reconstruct the species' phylogeography and demographic history. Results We found evidence that thylacines had contracted into separate eastern and western populations prior to the Last Glacial Maximum (c. 25,000 yr BP), and that the ancient western population was larger and more genetically diverse than the historical Tasmanian population. At the time of European arrival in c. 1800 CE, Tasmanian thylacines had limited mtDNA diversity, possibly resulting from a bottleneck event broadly coincident with an El Niño-Southern Oscillation (ENSO) associated climate event, although we find some indication that the population was expanding during the late Holocene. Main Conclusions The timing of this putative expansion, in concert with a climate event, suggests that climate change had an influence on thylacine population dynamics. Given that ENSO effects are known to have been more severe on mainland Australia, we suggest that climate change, in synergy with other drivers, is likely to have contributed to the thylacine mainland extinction.

Symbiosis

Symbiosis Used for interactions in which 2 organisms live together in a close relationship that is beneficial to at least one of them. It involves providing protection, food, cleaning and transportation for one of the organisms. The 3 types include parasitism, mutualism and commensalism.

Temperature: d) How is the factor measured and what units are used? e) What causes this factor to change? f) How does this change effect the organisms that live in the ecosystem?

Temperature: d) How is the factor measured and what units are used? Temperature is measured with a thermometer. The most commonly used units are Celsius (°C), Fahrenheit (°F) and Kelvin (K). e) What causes this factor to change? Causes for temperature to change include the amount of sunshine, temperature of the air mass, precipitation, reflectivity of the ground and cloud cover. Sunshine increases heat, a warmer air mass brings more heat. Cloud cover blocks incoming solar heat in the day, but also traps outgoing heat at night. Clear skies allow more solar energy during the day, but allows heat radiated by the earth to escape at night. Precipitation takes heat from the air as it evaporates, cooling the air. Snow takes a lot of energy to melt and evaporate which makes it reflective, inadequately absorbing the sun's energy. f) How does this change effect the organisms that live in the ecosystem? Many physical processes are affected by temperature including the physiology of living things as well as the density and state of water. It exerts an important influence on living organisms because few can survive at temperatures due to metabolic limitations. Enzymes are most efficient within a narrow and specific range of temperatures which can determine the efficiency of metabolic functions during certain temperatures that supports survival. Some animals also hibernate in certain temperatures. Hibernation enables animals to survive cold conditions and likewise for organisms that need to survive the harsh conditions of a hot, dry climate. Animals that hibernate or estivate can be affected by the temperature in order to continue their physiological adaptation of living in certain temperatures that aid their metabolic functions that supports its survival.

The niche includes how

The niche includes how a population responds to the abundance of its resources and enemies (e.g. by growing in numbers when resources are abundant, and predators, parasites and pathogens are scarce) and how it affects those same factors (e. g., by reducing the abundance of resources through consumption and contributing to the population growth of enemies by falling prey to them). The abiotic or physical environment is also part of the niche because it influences how populations affect, and are affected by, resources and enemies.

Population Dynamics Variables that influence population size include: Population growth rate Population Density Population Density

What is a population? The number of individuals of the same species in a given area at a given time. Population Dynamics Population dynamics is the study of changes in population size over time. Populations of organisms rarely remain at a constant level within an ecosystem, with many factors affecting their numbers. A stable population means that the resources required are sufficient to maintain the numbers of organisms. Where numbers are not constant there may be cyclical changes due to the amount of food, water and factors determining reproductive rates. Populations may decline due to disease, predation, competition from other species and human activities. Populations may increase due to an increase in the amount of food, lack of predators and competition and also human activities. Some organisms have adapted well to the condition in urban situations. Variables that influence population size include: 1. Birth Rate 2. Death Rate 3. Migration Rate (net gain or loss of individuals by movement into or out of the population). The combined action of these variables can produce changes in population size. This can be represented by the equation: Population growth rate = (births + immigration) - (deaths + emigration) Population Density - The number of organisms in a given area can affect the population due to competition for resources such as water and spread of disease. Population Density = the number of individuals/ area or volume occupied For example, if there are 2000 pine trees over an area of 10 square kilometres, the population density would be __200_________ pine trees per square kilometre. However, bacterial population density estimates may be 2 thousand bacteria per millilitre of blood. 3 Population Sampling Techniques Quadrat Transect Mark-Recapture Method

Wolves and the River

Wolves and the River The land of Old Faithful wasn't always so lush. Two decades ago, Yellowstone National Park was the victim of defoliation, erosion and an unbalanced ecosystem. But in 1995, everything changed. That was the year wolves were reintroduced to the park. Before then, government predator control programs had all but eliminated the gray wolf from America's lower 48 states. Consequently, deer and elk populations increased substantially, resulting in overgrazing, particularly of willows and other vegetation important to soil and riverbank structure, leaving the landscape vulnerable to erosion. Without wolves, the entire ecosystem of the park suffered. Wolves reinvigorated the park. "We all know that wolves kill many animals, but perhaps we're slightly less aware that they give life to many others," he says in the film. So much of our knowledge of these creatures focuses on their potential threat to humans, rather than their biological importance. As a top predator, wolves are one of Yellowstone's linchpins, holding together the delicate balance of predator and prey. Their removal in the early 20th century disrupted food webs and set off something called a "trophic cascade," in which the wolves' natural prey (in this case, elk) multiplied, all the while consuming increasing amounts of foliage. The phenomenon occurred again in reverse when the wolves were reintroduced and the natural balance was restored. When wolves were brought back to the park, they not only killed elk, but also changed their prey's behavior patterns. The herbivores started to avoid areas like valleys and gorges where they could be easily hunted by predators. As a result, those areas began to regenerate, and species such as birds, beavers, mice and bears returned. Plant life once again thrived along the riverbanks and erosion decreased significantly. The stabilization of the riverbanks actually made the rivers and streams change course. With the reintroduction of just a small population of wolves, the landscape of the whole park transformed. Earthjustice has been fighting in the courts and on Capitol Hill for more than 20 years to protect wolves. In recent years, anti-wildlife politicians have attempted to undermine the Endangered Species Act by slipping contentious policy riders into must-pass spending bills in an attempt to strip wolves of federal protections. In 2018, Congress added a record number of anti-wolf measures to House and Senate appropriations bills that fund the Department of the Interior, as well as to House defense authorization and energy bills. These measures would block Endangered Species Act protections for a variety of wolf populations, including: Mexican gray wolves, despite the fact that there are fewer than 100 of these imperiled animals left in the United States Gray wolves in Wyoming, Michigan, Minnesota, and Wisconsin, despite federal court decisions that found proposals to de-list these wolves illegal under the Endangered Species Act Gray wolves across the entire lower 48 states, despite the fact that wolves currently occupy just a small portion of their former range in the U.S. If we don't act now, wolves could again be subject to the same hostile extermination practices that pushed them to the brink of extinction. This video with George Monbiot demonstrates the importance of combating such legislation. Efforts to boost wild wolf populations are essential, not just for Canis lupus, but for the greater natural world.

Intraspecific Interspecific ALLELOPATHY SYMBITOIC MUTUALISM COMMENSALISM PREDATION

• In an ecosystem organisms (biotic factors) interact with other organisms. These interactions between organisms can be harmful, neutral or beneficial. Intraspecific = interactions between the same species Interspecific = interactions between different species COMMUNITY RELATIONSHIPS RELATIONSHIP EXAMPLE DESCRIPTION COMPETITION Interactions between the same species is called intraspecific. Interactions between different species is called interspecific. COMPETITION (GENERAL) Limpets and Black Nerita's both compete for algae on the rock platform. Weeds with other garden plants for soil nutrients, sunlight and water. Rabbits and wallabies for grass Two organisms both need the same limited resource for survival. E.g. food, shelter and mates. By aggression or physical interaction - vocalisation or leaving a scent for territory. ALLELOPATHY Casuarina Eucalypt release acid into soil Lantana Sorghum species release chemicals into root Black walnut chemicals that inhibit respiration The production by a plant of specific chemicals that can be detrimental to, or beneficial to, another. SYMBITOIC Interactions in which 2 organisms live together in a close relationship that is beneficial to at least one of them PARASITISM Worms eg. Tape, round, heart malarial protozoa Flea's Tick Lice Where one species obtains food from a host, causing harm to that host although it may not die. MUTUALISM Clown Fish and Anemone Reef building corals and algae Nitrogen-fixing bacteria and root nodules of legumes A relationship between two organisms where both benefit from the association. COMMENSALISM Epiphyte don't affect host tree Barnacles on a Whale A relationship where one species benefits and the other is not harmed. PREDATION Fox eats rabbit Spider and flies Blue-tongued lizard and beetles, snails Killer whale and seabirds, turtles, octopus and fish Venus flytrap and pither plant on insects One organism eat another