Biodiversity Biology ATAR Year 11 Biology 1AB Biology 3AB

Keywords Genetic biodiversity Species biodiversity Ecosystem biodiversity Biodiversity index Energy flow Energy transfer Energy transformation Food chain Food web Food pyramid Biomass Productivity

Definitions Ecosystem System formed by organisms interacting with one another and their physical environment Community All the living organisms in a habitat; the living part of an ecosystem Population A group of organisms of the same species living in a defined geographic area Species The basic category or group in the naming system of Linnaeus. Organisms that are grouped into the species usually closely resemble each other and interbreed.

Definitions Niche the role of an organism in an ecosystem, often defined by the environmental, biological and other conditions in which it lives. Biotic factors Relating to the biological parts of the environment as opposed to the abiotic (physical) parts Abiotic factors Relating to the physical parts of the environment, as opposed to the biological (biotic) parts

Ecosystems Ecosystems can be named according to: Climate ◦ Worldwide scale: biomes Habitat ◦ Freshwater, marine or terrestrial Dominant organisms ◦ Named after the largest or most dominant species eg. Mangrove forest

Biodiversity It can mean the variety of habitats, living communities and ecological processes in an ecosystem. It can mean the diversity of genetic characteristics within a species. It can mean the variety of species in a given area.

Importance of biodiversity Ecosystems depend on the combined contributions of the individual organisms within them. The loss of any species can prevent that ecosystem from operating the way it should. An ecosystem with a high level of biodiversity is more resistant to environmental change.

Measuring biodiversity A biodiversity index is a way of measuring biodiversity. Scientists use different biodiversity indices to measure diversity, depending on what is being studied. For some conservation studies, more than one measure may need to be used.

Measuring biodiversity Species Richness ◦ The total number of species in an area (add them up!) Species Evenness ◦ How evenly the species are represented in the area. ◦ e.g. do most of the individuals belong to one species?

Measuring biodiversity Species richness is a qualitative description… ◦ “how many different species can I see?” More species does not always mean more biodiversity because there may not be many individuals of each species (evenness) Species evenness is a quantitative measurement It is a measure of the abundance of individuals in each species.

Abundance can be measured… Percentage cover – the proportion of each quadrat occupied by the species. Population density – the number of individuals per quadrat Species frequency – the proportion of quadrats with the species in it.

Measuring biodiversity When both species richness and species evenness increase, there is by definition an increase in BIODIVERSITY.

Transfer of energy and matter Complex systems can be describes in terms of inputs, processes and outputs IPO model: Inputsprocesses outputs (+ storage) Example Photosynthesis Input = water & carbon dioxide Process = photosynthesis (driven by sunlight) Outputs = oxygen, water & glucose

Energy flow in ecosystems Energy flows through a community. Energy from the sun is captured by plants and converted into chemical energy which is then transferred along a food chain and used by each of the organisms for growth. At each link in a food chain, only 10 per cent of the energy is transferred from one level to the next. The rest of the energy is lost as heat or temporarily trapped in uneaten matter such as bone or fur. Because the amount of available energy decreases as we move up a food chain, most food chains can only support four or five links.

Food chains & food webs Food chains and food webs are examples of qualitative models. Energy is transferred from one trophic level to the next. (10%) Energy is also transformed from one trophic level to the next. (90%)

Consumers – mix ‘n match Primary consumer Secondary consumer Top consumer Omnivores Scavengers Detritivores Decomposers Dung beetle & earthworm Shark & eagle Kangaroo & sheep Fur seal & dingo Fungi & bacteria Goanna & vulture Human & bear

Trophic efficiency Animals differ in how efficiently they use the energy from food and how much of that energy can be passed on the next trophic level. Ectotherms will use less energy than endotherms Smaller animals will use less energy than larger animals Example Plants to insects to birds Plants to kangaroos The first food chain is longer because more energy is passed onto the next trophic level. The second food chain is very short because most of the energy from food is used (transformed) into heat and chemical energy

Food chains A food chain is a feeding relationship showing the transfer of energy through a chain of organisms

Food webs Food webs are integrated food chains Food webs are complex networks A food web represents the many possible feeding relationships in an ecosystem. Factors affecting their complexity: An organism can occupy different trophic levels in different, interconnecting food webs An organism can occupy multiple trophic levels in the same food web Migration eg. salmon

Food webs A food web, and therefore ecosystem, is more stable when many diverse predator-prey links connect high and intermediate trophic levels.

Food webs

Name the producers. Name an animal which has more than one food source and name its food source. What is the advantage to the animal of using different food sources? What role do bacteria play in the food web? What is the role of detritus feeders?

Food pyramids Food pyramids show the relationships of different trophic levels in a food chain. Trophic means ‘feeding’, and each trophic level in a food pyramid is a temporary energy storage step in a food chain or food web. Food pyramids are quantitative models.

Stepped Pyramid

Why are trophic levels usually shown in the shape of a pyramid? A pyramid shape is used because the transfer of matter and energy from one trophic level to the next is not very efficient. Only 10 per cent of matter and energy from one trophic level makes it to the next so each trophic level will be smaller than the previous one.

Biomass The biomass of an ecosystem is the total dry weight of biological material in the community. It is measured in dry weight per unit area.

Biomass

Productivity Productivity in an ecosystem is the rate at which biomass accumulates or energy is stored. The amount of biomass produced per year varies between communities. This is because the rate of productivity of the autotrophs varies according to a range of growth conditions such as:  water availability  light intensity  nutrient availability  temperature Communities with producers that grow and survive have the largest biomass levels. CommunityProductivity (kg/m2) Rainforest2.0 Woodland1.2 Grassland0.6 Desert0.1 Coral reef2.2 Open ocean0.1 Swamp and marsh 1.5