ecosystems

ecosystems → interaction of many organisms functioning together through physical and chemical environments, composed of biotic and abiotic factors that cycle
- four hierarchical layers → ecosystem, community, population, individual
the ecotone → the intermediate zone between two systems a transitional zone from one type of ecosystem to another
- some species live in particular ecotones like marshlands
biomes → grouping ecosystems from a particular region into landscapes
structure of ecosystems → non-living are the physical-chemical aspects, i.e. local climate, water, soil, and temperature; living is the ecological community, a set of species interacting within ecosystems
process of ecosystems → cycling of chemical elements and flow of energy through systems
change in ecosystems → succession; ecosystems aren’t static and are always changing
five important cycles → water, carbon, nitrogen, phosphorus, and sulphur
non-living/abiotic factors → abiotic factors affect the ability of organisms to survive, each individual in a population can have a slightly different response to the abiotic environment, reflecting the sum of individual variation
- the nature of a particular ecosystem is the result of the underlying variation in both abiotic factors and populations’ responses
generalist species → species that have wider ranges of tolerance and can live in a variety of habitats, i.e. raccoons, rats
specialist species → species that have narrow ranges of tolerance and have a restricted distribution, i.e. pandas
species niches → the summation of all physical and abiotic factors that a species needs to live
- species population numbers will be highest wherever all relevant environmental conditions are optimal
- restricting any one of the environmental factors that influence an organism will limit the population
food chains → energy, chemical elements and components transferred from one creature to another
food webs → more complex cases, non-linear, have the same underlying trophic patterns: at the top, secondary consumers/carnivores (heterotrophs), then primary consumers/grazers/herbivores (heterotrophs), producers (plants/autotrophs), and tertiary consumers/decomposers at the bottom
autotrophs (self-feeders) → feed themselves through photosynthesis
photosynthesis → the process of turning inorganic carbon into organic carbon and capturing energy
heterotrophs (other feeding) → feed themselves by consuming organic carbon already fixed by autotrophs and extracting its energy via respiration, which is then available for growth reproduction
2nd law of thermodynamics → tells us there will be an inevitable loss of useful energy with the progressive movement to higher and higher trophic levels, and eventually there won’t be enough energy to support an additional trophic level
all systems are interconnected → terrestrial biomes are connected by rivers, sediments and nutrients from land wash into aquatic ecosystems, all share a common hydrologic cycle and a common atmosphere
the biosphere → term referring to how all species on Earth and their environments can be considered one vast ecosystem
keystone species → species that drive the functioning of whole ecosystems and have a critical role in maintaining the overall relationships within an ecosystem; a strongly interacting species that has a top-down effect on the diversity and competition that is large compared to its biomass
- can only be determined by looking at whether it is or isn’t present in the ecosystem
- i.e. seat otters live in kelp forests and help maintain the integrity of kelp forest ecosystems by controlling sea urchins, who eat kelp
  - loss of sea otters causes sea urchin numbers to grow exponentially causing them to drive kelp to extinction
geographic variation → the variation in kinds and numbers of species found on the planet
biomes → characteristic assemblage of plants and animals that have adapted and evolved to specific climatic conditions can be classified by a system corresponding to latitude and humidity
- community > ecosystem > landscape > biomes
terrestrial biomes → tundra, desert, boreal forest, tropical rainforest, tropical dry forest, savanna, mountains with complex zonation, chaparral, temperate grassland, temperate deciduous forest and temperate grassland
precipitation and biomes → how wet an area is can shape the environment
high latitude biome → less variation; temperature is more important than precipitation in shaping the biome
lower latitude biome → precipitation and the amount of moisture are more important in shaping the biome, similar temperatures and the amount of precipitation determine whether it’ll be a tropical rainforest or a dry tropical desert
gross primary productivity (GPP) → the amount of organic matter that is produced through photosynthesis, though not necessarily the amount that can be moved up to the next trophic level
net primary productivity (NPP) → the amount of energy available for plant growth after subtracting the fraction that plants use for respiration, what is available for the next trophic level
- GPP - respiration = NPP
- varies across the earth, increases where there is a lot of plant growth
top-down regulation of ecosystem functions → abundance of predators determines the trophic levels that exist in a particular system
bottom-up regulation of ecosystem functions → resource availability at the bottom (plant mass) determines or controls how that ecosystem functions
ecological niche → what an organism does for a living, how many herbivores, predators, etc in an ecosystem; measured as a set of all environmental conditions under which species can persist and carry out its life function
competition exclusion principle → two species that have exactly the same requirements cannot coexist in exactly the same habitat, niche overlap leads to competition over the same resource
habitat complexity → when a habitat has a variety of different niches, it allows for more different kinds of species to exist
fundamental niche → having a wide tolerance range; doesn’t guarantee a species will occupy the whole of the niche
realized niche → biological interactions with other species may restrict organisms to a realized niche that is a smaller fundamental niche
symbiosis/mutualism → interactions between species that benefit both, the most popular relationship found in ecosystems, the most efficient
- i.e. pollination mutualism - bees collect pollen from one plant and carry it to another (cross-pollination)
competition → interactions between species where the outcome is negative for both, not sustained over a long-term
- i.e. 5 species of wood warblers and the differences between their fundamental and realized niches, avoid competition by partitioning their habitat or by co-existing
- competition is energy-intensive
parasitism (predator) → interactions between species that benefit one but are detrimental to another
- i.e. wasp larva on a caterpillar
co-existing species → species of organisms coexisting today could be the result of competitive interactions that took place thousands or millions of years ago
- the advantage to co-existing or avoiding competition is the optimization and allocation of energy
- species cannot adapt at the rate that human interactions and destruction occur