genomes to ecosystems lecture 7- individuals, communities and population Flashcards
what are the three levels of an ecosystem?
community, population and individual
is population the same species?
Because we’re discussing organisms at a specific time & place, using ‘population’ is more accurate. Populations are of the same species so they could theoretically interbreed, but don’t for some reason – geographic separation, ecological separation, different times
what are key biological processes?
Growth, Metabolism, Activity, Thermoregulation, Reproduction
why do they need to reproduce?
Need animals to produce more animals: individual survival & fitness
Reproduction is only process that really affects POPULATION, but as a result of all the survival processes, those reproductive resources only constitute a part of the overall energy available within an individual. They also must be allocated WITHIN reproduction and those differences affect how likely a population is to survive under certain environmental conditions
what is succession?
sequence of development of vegetation from a sterile surface
what is primary succession?
a new bare surface such as emergence of a new island, a mud volcano - mud, fine sand and a solid rock
what is secondary succession?
destruction of existing vegetation such as Deforestation, human-related destruction of habitat, natural destruction
what is an example of secondary succession?
History:Cricket field
War
School ground
Football field
Sowed grass
Unmanaged, litter
Series of motivations for green space for the community, now managed by volunteers and show facilitated regrowth (visit during Biol2A lab: Habitat Differences)
what is the initiation stage?
bare substrate, no vegetation and 0 adaptations
what is the colonisation stage?
low-nutrients, low water, unstable soil. bryophytes and lichens. stress tolerant, small, rapidly growing and reproducing
what is the development stage?
stable soil, grasses and seeds. competitive and disturbance tolerant adaptation
what is the mature stage?
stable, nutrient and water rich soil. competitive grasses, bushes and small trees. less disturbance tolerant
what is the climax stage?
stable, nutrient rich soil. large trees and is now long lived and disturbance intolerant
what are density independent processes?
factors that have nothing to do with the size of the population itself, generally abiotic factors such as floods and volcanic eruptions
what are types of stressors which affect all individuals regardless of the size of population?
wind-Cold temperatures, High winds, High UV
light- Low PAR (<1% energy above canopy)
salt-High salt toxic to plants, desiccates cells
water-Desiccates cells, Reduces photosynthesis
temperature- Damage due to freezing, water loss
ph-Damage from toxic compounds; change gas exchange
how does dispersal affect population
Dispersing individuals leave natal area to find a new location to survive as adults. Often happens early in life (larval, seed, juvenile) to avoid problems of overpopulation (leave territory of parents)
what are advantages of dispersal
Finding resources
Finding better conditions
Reducing competition
Avoiding inbreeding depression
what are disadvantages of dispersal
Energy cost
Increased risk of predation
Lack of settlement
what is competition?
Competition: negative effects by one organism consuming or controlling access to a limited resource
what are the outcomes of competition?
Coexistence: Ecological differentiation
Elimination: Dominant species ousts (‘outcompetes’) others
what species are good competitors?
Good competitors: Broad distributions, abundant
Influence distribution of other species
Competition based on success of traits and stress/disturbance trade-off
what is the result of competition?
dominant get their preferred and subordinate get the suboptimal
what does assemblage mean?
Assemblage: collection of interacting populations in the same geographic area
Few organisms occur simply in their own population. Most populations occur in the same place as a range of other species, so have the same resources available. Some assemblages consist of a food web, where some populations require others to survive, whereas others are competing for the same resource.
what does fundamental niche mean?
Fundamental Niche: set of resources under which organisms COULD survive
what is the realised niche?
set of conditions under which a group of organisms ACTUALLY survive
what are invasive species?
Invasive species evolved under a different set of evolutionary pressures and in different communities of predators, so when they arrive in a new location without those, they can outcompete native species, both dominating resources, predating on native species and spreading disease
what are examples of invasive species?
giant hogweed, rhododendron, American skunk cabbage, Himalayan bales, killer shrimp, carpet sea squirt, harlequin ladybird, American signal crayfish and American mink
what does success require?
Success requires some advantage to access different resources as rest of crowd eg darwins finches
what is spatial variation?
Mosaic of stresses & disturbances: ‘patches’
More habitats, niches = higher biodiversity
what is temporal variation?
Changes throughout period of time
Predictable variation = predictable response
such as months and seasons
how does population of organisms vary?
predation, disease, parasitism, competition