W8 Microbial Interactions

Question 1

properties of mutualism

Answer 1

some reciprocal benefit to both partners

relationship with some degree of obligation > partners may need to live together

mutualist and host can be dependent on each other

endosymbiotic microbe provides needed vitamins and amino acids

examples: deep sea tube worms, coral-zooxanthellae

Question 2

definition of cooperation

Answer 2

along with commensalism, is a positive, but not obligate form of symbiosis which involves syntrophic relationships

benefits both organisms in relationship

differs from mutalism as cooperative relationship is not obligatory

Question 3

definition of commensalism

Answer 3

interaction between two species, where one organism benefits from it but the other is neither helped or harmed

commensal: organism that benefits

often involve modification of environment by one organism > making it more suitable for other organism

Question 4

definition of syntrophic relationships

Answer 4

when 2 or more species cooperate metabolically

Question 5

definition of parasitism

Answer 5

one organism benefits (parasite) and other is harmed (host) > measures as reduced size and fecundity

always some co existence between host and parasite

successful parasites evolve to co-exist with host ; if balance upset > host or parasite may die

Question 6

definition of ammensalism

Answer 6

negative impact of one organism on another based on release of a specific compound

Question 7

definition of competition

Answer 7

occurs when two organisms try to acquire or use the same resource

one organism dominates: two organisms overlap too much in their resource use and one population is excluded

two organisms share the resource > both survive at lower population levels

Question 8

definition of interaction chain

Answer 8

when a donor species affect the abundance of a transmitter > has effect on a recipient

Question 9

definition of interaction modification

Answer 9

when the donor species alters some other attribute of the transmitter such as behaviour

Question 10

definition of dominant, foundation and keystone species

Answer 10

dominant: species whose influence on their community is due to their high relative abundance

foundation: influences community by physically changing environment

keystone: species whose influence on its ecosystem and community is disproportional to its abundance

Question 11

what is quorum signalling

Answer 11

bacteria release chemical signals into their environment

when concentration of signal reaches a certain threshold indicating high population density > bacteria collectively change their behaviour