Ecology & Conservation (studying for IB Biology SL paper 3)

Simpson's reciprocal index of diversity

1. use a random sampling technique to search for organisms in the ecosystem. 2. identify each of the organisms found. 3. count total number of individuals of each species. 4. calculate the index (D). D = N(N-1) / Σn(n-1). N: total number of organisms. n: number of individuals per species.

energy losses in food chains

3 main reasons: • some organisms die before they are eaten by the next organism in the food chain. • some parts of organisms are not eaten (bones, hair and gall bladders). • some parts of organisms are indigestible (cellulose in food eaten by humans → egested in feces).

mesocosm

A biological system that contains the physical features and organisms of an ecosystem but is restricted in size or scope for use in conducting scientific experiments.

primary succession

An ecological succession that occurs following an opening of uninhabited, barren habitat or that occurs on an environment that is devoid of vegetation and usually lacking topsoil. ex: An example of primary succession is the initial development of plant or animal communities in an area where no soil initially exists (such as caused by a lava flow following volcanic eruption or severe landslide that covered the land)

consumer

An organism that generally obtains food by feeding on other organisms or organic matter due to lack of the ability to manufacture own food from inorganic sources.

light energy

Light energy affects water temperature, biological processes (such as the relationship between predators and prey) and plant photosynthesis and growth. Under natural conditions light is controlled by topography, cloudiness, vegetation cover, and seasonal patterns, like less daylight in the winter. it is the initial energy source for a whole ecological community.

secondary succession

The ecological succession that occurs on a preexisting soil after the primary succession has been disrupted or destroyed due to a disturbance that reduced the population of the initial inhabitants. ex: An example of secondary succession is the development of new inhabitants to replace the previous community of plants and animals that has been disrupted or disturbed by an event (e.g. forest fire, flood, harvesting, epidemic disease, pest attack, etc.).

ecosystem

a biological community of interacting organisms and their physical environment.

environmental disturbance

a disturbance is a temporary change in environmental conditions that causes a pronounced change in an ecosystem. disturbances often act quickly and with great effect, to alter the physical structure or arrangement of biotic and abiotic elements. ex: fires, floods and storms (natural) and/or introduction of alien species, logging of forests and land drainage (humans).

limiting factors

a factor present in an environment that controls a process, particularly the growth, abundance or distribution of a population of organisms in an ecosystem. ex: the availability of food, water, nutrients, shelter, and predation pressure.

food chain

a feeding hierarchy in which organisms in an ecosystem are grouped into trophic (nutritional) levels and are shown in a succession to represent the flow of food energy and the feeding relationships between them.

climograph

a figure which shows the relationship between temperature, rainfall and the type of stable ecosystem that is predicted to develop.

food web

a graphical model showing the interconnecting food chains in an ecological community.

species

a group of closely related organisms that are very similar to each other and are usually capable of interbreeding and producing fertile offspring.

population

a group of organisms of one species that interbreed and live in the same place at the same time (e.g. deer population).

biological control

a method of controlling pests such as insects, mites, weeds and plant diseases using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role.

fundamental niche

a niche that an organism could potentially occupy. this means, 'the entire area an organism can live in, disregarding limiting factors.'

transects

a path along which one counts and records occurrences of the species of study (e.g. plants). It requires an observer to move along a fixed path and to count occurrences along the path and, at the same time (in some procedures), obtain the distance of the object from the path.

predation

a predator killing its prey.

herbivory

a primary consumer feeding on a plant or its products.

mutualism

a relationship between two different species where both species have some degree of physiological dependency on one another and benefit from the relationship.

parasitism

a relationship between two different species where only one species benefits and the other one is usually harmed.

biotic index

a scale for showing the quality of an environment by indicating the types of organisms present in it. It is often used to assess the quality of water in rivers.

alien species

a species introduced outside its normal distribution. invasive alien species are alien species whose establishment and spread modify ecosystems, habitats, or species.

keystone species

a species that has a disproportionately large effect on the communities in which it occurs. it may be a dominant predator or an organism that can greatly alter the environment (corals, beavers, etc).

abiotic environment

all physical and nonliving chemical factors, such as soil, water, and atmosphere, which influence living organisms.

producer

an autotrophic organism capable of producing complex organic compounds from simple inorganic molecules through the process of photosynthesis (using light energy) or through chemosynthesis (using chemical energy).

climax community

an ecological community in which populations of plants or animals remain stable and exist in balance with each other and their environment.

closed ecosystem

an ecosystem that does not exchange nutrients with its surroundings.

open ecosystem

an ecosystem which undergoes significant exchange from the surrounding environment.

indicator species

an indicator species is an organism whose presence, absence or abundance reflects a specific environmental condition. Indicator species can signal a change in the biological condition of a particular ecosystem, and thus may be used as a proxy to diagnose the health of an ecosystem.

community

an interacting group of various species in a common location.

competition

an interaction between organisms or species in which both the organisms or species are harmed. Limited supply of at least one resource (such as food, water, and territory) used by both can be a factor.

autotrophs

an organism capable of synthesizing its own food from inorganic substances using light or chemical energy (photosynthesis).

heterotrophs

an organism that cannot manufacture its own food and instead obtains its food and energy by taking in organic substances, usually plant or animal matter.

ex situ conservation

animal conserved away from its natural habitat. • will work if habitat is lost • easy to isolate the animal from threats • species maybe too rare to breed / maintain population in the wild • captive breedings can quickly increase numbers (for some species)

in situ conservation

animal conserved in its natural habitat. • natural habitat is conserved • maintain's the animal's normal behavior • food web / chain structure of the ecosystem maintained

feed conversion ratio (FCR)

conversion ratio = intake of food (g) / net production of biomass (g). the higher the ratio, the less energy converted into biomass.

energy pyramids

diagrams that show how much energy flows through each trophic level in a community.

endemic species

endemism is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere.

nutrient storage compartments in an ecosystem

energy enters ecosystems, flows through food chains and is then lost from the ecosystem. in contrast, nutrients can be retained in an ecosystem for an unlimited time. in terrestrial ecosystems, there are three main storage compartments: biomass (living organisms), litter (dead organic matter) and the soil. nutrients flow between these compartments (this can be illustrated through Gersmehl diagrams).

chi-squared test

expected frequency = row total x column total / grand total. significance level is usually 5%.

evenness of biodiversity

how close in numbers the different species are. ex: 5 butterflies, 5 ants = even. 6 butterflies, 2 ants = uneven.

macroplastic debris

large visible plastic debris (> 1 mm).

DDT and malaria

malaria → mosquitoes → need to kill them → spray of DDT → this insecticide also started killing other insects and biomagnification started occurring too → devastating effects on top carnivores → ban of DDT → raise of malaria again → controversial topic.

saprotrophs

organisms than obtain organic nutrients from dead organisms by external digestion. ex: some bacteria and fungi.

detritivores

organisms that obtain organic nutrients from detritus by internal digestion. ex: earthworms, fiddler crabs and sea cucumbers.

comparison of energy pyramids

questions to ask: • how many trophic levels are there? • how much gross production by producers is there? • how much energy reaches each trophic level? the most productive ecosystems have high gross production by producers, so large amounts of energy flow to higher trophic levels and there can be a relatively large number of trophic levels.

microplastic debris

small plastic debris (< 1 mm).

net production

the amount of energy converted to biomass in an organism (always less than gross production — some energy lost from cell respiration).

zone of stress

the area in a populations geographic range where members of population are rare due to physical and biological limiting factors.

biomagnification

the increasing concentration of a substance, such as a toxic chemical, in the tissues of organisms at successively higher levels in a food chain. ex: the radioactive isotope caesium-137 was released by the Fukushima nuclear disaster. levels of it were measured in organisms from marine food chains near the area. killer whales (orca) reached caesium-137 levels that were 1000x high than Chinook salmon (their main prey) and 13,000x higher than phytoplankton at the start of the food chain.

edge effects

the influence that two ecological communities have on each other along the boundary (called the ecotone) that separates them.

humans and the nutrient cycle

the nitrogen cycle is greatly affected by human activity (extra inputs — ex: fertilizers in agriculture). these extra inputs to the nitrogen cycle cause eutrophication and algal blooms.

richness of biodiversity

the number of different species present. ex: elephants, zebras, lions, grasshoppers = rich. only elephants = not rich.

realized niche

the part of fundamental niche that an organism occupies as a result of limiting factors present in its habitat. this means, 'the actual area an organism is able to live in because of the effects of limiting factors.'

eutrophication

the process by which a body of water becomes enriched in dissolved nutrients (such as phosphates) that stimulate the growth of aquatic plant life usually resulting in the depletion of dissolved oxygen.

distribution of a species

the range of places a species inhabits. plant & animal species are limited in their distributions because of abiotic factors.

ecological niche

the role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces. A species' niche includes all of its interactions with the biotic and abiotic factors of its environment.

gross production

the total amount of energy in food assimilated by an animal or in food made by photosynthesis in producers.

limit of tolerance

the upper and lower limits to the range of particular environmental factors (e.g. light, temperature, availability of water) within which an organism can survive.

consumers

they feed on living organisms by ingestion. ex: humans!

competitive exclusion principle

two species cannot survive indefinitely in the same habitat if their niches are identical.

mutualism in reef-building corals

• most corals that build reefs contain mutualistic photosynthetic algae called zooxanthellae. • the coral provides the alga with a protected environment and holds it in position close to the water surface where there is enough light for photosynthesis to occur. • the zooxanthellae provides the coral with products of photosynthesis such as glucose, amino acids and also oxygen. • the coral's waste products are all used by the zooxanthellae: carbon dioxide, ammonia and phosphates. • this mutualistic symbiosis allows corals to form coral reefs (the zooxanthellae improve their nutrition enough for that to be possible).

exceptions to → plant = autotrophic

• parasites. ex: dodder (Cuscuta) and broomrape (Orobanche) are never green and cannot synthesize their own food. In such cases, they develop haustoria or sucking roots which go into the vascular bundles of the host plant and absorb from them the prepared food and water. • symbionts. ex: Lichens and mycorrhiza. • insectivorous plants. ex: the sundew plant is a small herb. an insect landing on the leaf gets stuck and the glandular hairs bend down and prevent the insect from escaping. the enzymes secreted by the hairs digest the insect and the products are absorbed by the leaf surface.