B3 - Studying Organisms in Ecosystems (Updated 2024) PDF

B3 - Studying Organisms in Ecosystems I can… Explain how terrestrial and aquatic ecosystems support a diversity of organisms Identify biotic and abiotic characteristics and explain their influence on aquatic and terrestrial ecosystems Explain how limiting factors influence organism...

B3 - Studying Organisms in Ecosystems I can… Explain how terrestrial and aquatic ecosystems support a diversity of organisms Identify biotic and abiotic characteristics and explain their influence on aquatic and terrestrial ecosystems Explain how limiting factors influence organism distribution and range Studying Organisms in Ecosystems Life on Earth isn’t evenly distributed Abiotic factors often dictate productivity of an ecosystem and will have major effects on distribution of living things ○ Organisms can tolerate changes in abiotic conditions, but only within a certain range Ecotones and Biodiversity Ecosystems rarely have sharp boundaries, they often move between different ecosystems Ecotones: A transition area between ecosystems ○ Often contain greater biodiversity than either individual ecosystem Increased biodiversity = less fragile ecosystem If a predator has to rely on a single species as a food source, then it is depending exclusively on that prey. If it has various preys, then it is more likely to survive. By providing multiple food sources, ecotones helps to guard against extinction. Roles in Ecosystems Ecological niche: An organisms role in an ecosystem, consisting of its place in the food web, its habitat, its breeding area, and the time of day at which it is most active Includes everything an organism needs to survive Each species in an ecosystem has a different niche (different role to play) Important to reduce competition Roles in Ecosystems Owls and hawks feed on similar organisms (snakes, mice, gophers) but occupy different niches. Roles in Ecosystems Each species of warbler prefers to feed in different sections of the tree, so competition is reduced. Competition for Niches When a new species enters, there is a disturbance in the ecosystem The new species comes into competition for a niche with pre-existing species Exotic species are not native to the ecosystem Often happens naturally because: ○ Animals are mobile ○ Plant seeds are spread through the wind or animals The opossum, once native to South America, can now be found in North America when the Americas came together ~5 million years ago. It competed for and established it own niche in forest ecosystems. Introduction of Exotic Species New species can also be introduced by humans ○ This is one of the main causes for species depletion and extinction (habitat loss is the main one!) Indigenous (native) populations may be weaker than the exotic species due to predators or disease ○ May not be able to compete for food, space, reproductive sites ○ Native prey organisms may not have defense mechanisms against introduced predator species Introduction of Exotic Species In 1890, a Shakespeare fan collected and transported all the birds mentioned in the Bard’s plays from the UK to Central Park, NYC. A pair of starlings multiplied so quickly that they are now one of the most prominent bird species in North America Starlings settle in prime nesting sites, and evict mountain swallows and bluebirds from their nesting sites Due to this, the indigenous bluebird population has decreased There have been less than 3000 introduced species in Canada. Biomes Biome: A large geographical area with a specific range of temperatures and precipitation, and the organisms that are adapted to those conditions of temperature and precipitation Each biome has a dominant species, for example: ○ Coniferous trees in the taiga biome ○ Prairie grasses in the grassland biome Biomes in Canada There are 4 main terrestrial biomes and 2 major aquatic biomes in Canada: Terrestrial Tundra Grassland Taiga Temperate deciduous forest Aquatic Fresh water Saltwater Ecosystem Diversity In terrestrial ecosystems, precipitation and temperature are the main predictors of diversity Which biome do we expect to have the most diversity? The least? Patterns in Ecosystem Diversity As a result, diversity is positively correlated with proximity to the equator Patterns in Ecosystem Diversity Earth’s atmosphere is unequally heated Causes Earth’s major climate zones: ○ Tropics: Near equator ○ Temperate zone: Middle ○ Cold regions: Near poles Affect surface temperature and movement of ocean and atmospheric conditions Affects abundance of plants and other photosynthetic organisms Taiga Biome Also called boreal forest biome Found throughout Alberta and the Rocky Mountains Found in every province Comprises 80% of forests The major species in the taiga biome are conifers (cone-bearing trees) Contains many different ecosystems Taiga Biome Conifers adapted to cold dry winters and warm moist summers Thin needle-shaped leaves provided less surface area for water loss during winter ○ Wax coating prevents frost and water loss ○ Pyramid shape and flexible branches shed snowfall Conifers are a suitable food source for ~50 species of birds Forest floor provides continuous shade Species in taiga biome: shrubs, mosses, ferns, moose, voles, deer ○ Predators: Bears, weasels, owls, wolverine Aquatic Ecosystem Diversity In aquatic environments, amount of available light is often the main determining factor in abiotic niches ○ Upper layer: Significant amount of light for photosynthesis ○ Deeper layer: Cooler In general, the deeper you go, the less diversity you will find Aquatic Ecosystem Diversity Aquatic Ecosystem Diversity Littoral zone: The area from the short of a lake or pond to the point where no more plants grow in the lake bottom Limnetic zone: The area of a lake or pond in which there is open water and sufficient light for photosynthesis to occur Plankton: Autotrophic and heterotrophic microorganisms found in the limnetic zone of a lake or pond Profundal zone: The region of a lake beneath the limnetic zone, in which there is insufficient light for photosynthesis to occur, detritus falls and is broken down here Growth-Limiting Factors Two types: ○ Abiotic: Producers in particular are limited by abiotic factors of the environment: soil type, moisture, humidity, level and temperature range ○ Biotic: Affect rate of growth Biotic limiting factors are classified by one of the following: ○ Competition ○ Predation ○ Parasitism Competition Competition: There are finite (limited) amounts of each resource available in each ecosystem, therefore, there is competition for Intraspecific competition these resources Two kinds: ○ Intraspecific competition: Members of same population compete for limited resource ○ Interspecific competition: Competition for resources between species when two different species occupy the same niche Interspecific competition Predation Predation: Biotic interaction that involves consumption of one organism by another Predators that feed on multiple prey types will affect numerous food chain relationships Parasitism Parasitism: Interaction in which the parasite derives nourishment from another organism: the host, who is harmed in the process ○ Host is not always permanently harmed If there was an increase in the density of host population, parasites can more easily pass between the host, increasing the number of parasites Parasitic infestation will limit reproductive and survival ability of host decreasing its density Population Sampling Ecologists often estimate the size of population ○ Most commonly count/estimate the number of individuals in number of samples ○ Smaller portions of entire population are calculated, then averaged over entire area Sample transect When sampling, the following is used to divide study areas into smaller area: ○ Transect: Samples along a very long rectangle Organisms are counted within certain distance from line ○ Quadrat: Several locations within study are chosen and at each location, a quadrat of the same size is marked out Number of species within each quadrat is counted Quadrats