unit 9 - how do species interact?

what is robert paine’s experiment

Paine conducted an experiment to determine the effects of the removal of the top predator and whether it would result in catastrophic consequences or makes the ecosystem less stable.

He removed the pisaster ochraceus from one ecosystem, and kept another untouched

Observed for ten years

Unstable and unhealthy, ecosystem was not diverse. fell from 8-15 to 1-2 dominant species.

impact of removing the top predator from an ecosystem

population explosion, trophic cascade, behavioral changes

population explosion

Increase in prey species as there is no predator to hunt them

If there is shortage of number of prey, population of the predators decrease as there is not enough sources of food. Will decrease until a sufficient number or abundance in the prey species.

trophic cascade

A trophic cascade is an ecological phenomenon where changes to a top predator population cause ripple effects down the food web, dramatically altering lower levels like herbivores and plants, often leading to major ecosystem shifts

behavioral changes

Prey will change eating habits as there are no predators to be wary about

producer

Autotrophic organism that produces complex compounds from inorganic molecules through photosynthesis

trophic level

position an organism occupies in a food chain

niche

functional role of a species within an ecosystem

consumer

heterotrophic organism that obtains food and energy by feeding on other organisms to obtain sufficient amounts of energy

omnivore

organism that feeds on both other organisms and plants to obtain sufficient amounts of energy

saprotroph

organism that absorbs soluble organic nutrients from inanimate sources. They live on or in non-living organic matter

detritivore

consumes decaying organisms or organic waste

food chain

feeding hierarchy representing the flow of energy from one organism to the next

photosynthesis

process by which autotrophic organisms transform energy from the sun into chemical energy

chemosynthesis

process by which certain organisms extract inorganic compounds from their environment and convert them into organic compounds without the presence of sunlight

differences between photosynthesis and chemosynthesis

photo:

requires light energy

occurs in plants and some bacteria

products are oxygen and glucose

doesn’t require oxygen

chemo:

darkness on sea floor

use of energy released by inorganic chemical reactions

products are sulfur, sugar, water

requires oxygen

requires hydrothermal vents to be able to synthesize

similarities between chemo and photosynthesis

carbon dioxide is required as a reactant

both reactions take place in autotrophic organisms

sugar is a rpoduct that is formed.

symbiosis

interaction between two or more species that live together in a close long-term association

mutualism

symbiotic association where both organisms benefit from the interaction

bees and plants (bees get nectar, plants get polinated)

commensalism

symbiotic relationship where one organism/species benefits in which the other species/organism is neither harmed nor benefited.

birds use tree branches for roosting sites

parasitism

relationship where one organism, parasite, benefits at the expense of the host causing it harm often stealing nutrients

ticks

predation

interaction where one organism feeds on another organism. directly benefits predator and directly harms prey

competition

occurs when two organisms struggle for the same resources within an environment

intraspecific, interspecific

intraspecific

competition among same species

interspecific

competition among different species

keystone species

a species whose importance in an ecosystem’s structure and function is disproportionately large in comparison to their abundance. They have low functional redundancy. for example beavers, otters, and star fish

low functional redundancy meaning

no other organims would be able to fill its ecological niche.