Flashcards in lecture 3 - ecology Deck (30):
The relationships between organisms and their physical surroundings
all living things on earth
larger ecosystem (ocean)
-“A dynamic complex of plant, animal and microorganism communities and the abiotic (non-living portion) environment, interacting as a functional unit”
-Influenced by abiotic factors like temperature, nutrient availability, humidity, pressure, pH, O2 concentrations, etc.
Interacting populations of different species
occur in same geographic location at same time
Communities form part of the larger ecosystem
ex) the microbial community on your left elbow
a group of individuals of the same species occupying a region.
Frequently defined by geography
-Prairies vs. forests (Bison bison)
-Lung vs. gut (P. aeruginosa)
1. An organism’s habitat and food requirements
-E. coli thrives in the mammalian intestine, can eat glucose and lactose
2. An organisms’ functional role within the ecosystem
E. coli uses O2, thus contributes to keeping the intestine anaerobic
**influenced by abiotic and biotic factors
Organisms living in a mutually beneficial relationship
ex) Human host and bacteroides in intestine
relationship benefits one organism and the other is unaffected (is any interaction ever neutral?)
ex) Human and Haemophilus influenzae in ear - usually benign --> can protect against staphococcus (mutualism) or can be parasitism too
host is harmed in some way while the parasite benefits
what is nutrient acquisition? what type of relationship is this?
cows eat grass, bacteria in their stomach break down grass (cellulose) into fatty acids and protein, cow digests these NOT grass
when do competitive interactions occur
-overlaping niches cause competition for resources (food, space, minerals)
-ability to compete influences number of organisms
-can cause exclusion of a species from an environment which can be problematic
ex) c.diff is minor member of gut community - over use of antibiotics removes competitors and it had ability to overgrow creating GI issues
what is meant by: species within an ecosystem are interconnected and interdependent
Changes that influence one species can, through relationships with other species, result in changes throughout the entire community and ecosystem
what is succession? and how does it occur
changes in community structure.
-caused by changes in environmental conditions (internal - seasonal,nutrients, host age, external - antibiotics)
what are the consequences of succession?
-changes are unanticipated and occur at various scales
-c.diff overgrowth d/y antibiotics killing normal gut flora
what influences chance of encountering microbes?
microbe distribution (where in environment)
what influences likelihood of infection?
micrbe abundance (how many it takes to cause infection)
Uses inorganic CO2 as its carbon source (not nutritionally dependent on other living things)
-Photosynthetic organisms like plants
Must obtain carbon in organic form (nutritionally dependent on other living things)
Humans, E. coli
organic molecules as energy
uses light as energy
uses inorganic molecules (H2S) as energy
use oxygen for metabolism, and have antioxidants
require O2 (humans)
-grow at air-liquid interface
optimal growth in O2, but can grow without O2
-E. coli, Salmonella
-grow throughout tube
grows at lower O2 concentrations
don’t have metabolic enzymes for using O2
are killed by O2
ex) Bacteroides (dominant bacteria in healthy human gut)
-grow below surface, away from O2
don’t require O2 but can survive in environments with oxygen.
-some members of Clostridium