Ecology Flashcards
Rocky Shore Write-up (17 cards)
Niche Partitioning
The process by which natural selection drives competing species into different patterns of resource use or different niches. Coexistence is obtained through the differentiation of their realized ecological niches. This may mean occupying a different space, being active at a different time, or changing the method of resource use in some way.
Niche
How an organism feeds and where it lives. No two species may occupy the same niche at the same time, as one would out-compete the other.
Limiting Factor
A resource that, when in short supply, can prevent unlimited growth.
Carrying Capacity
Largest number of individuals of a population that a environment can support. When a population exceeds carrying cpacity its numbers will fall.
Gause’s Principal of competitive exclusion
No two species can occupy the same niche, one will be better adapted and will out-compete the other.
Zonation
A pattern of distribution, that, on the rocky shore, takes the form of horizontal bands of species parallel to the shore caused by a gradient in the amount of time spent submerged. Different species are more suited to different conditions.
Abiotic Factors
Non-living factors, i.e: Temperature, tide, water-coverage, humidity, exposure, dissolved oxygen, wind, etc.
Biotic Factors
Living factors, relationships with other organisms, competition, predation, mutualism, parasitism, herbivory, etc.
Tolerance
The range of physical factors that an organism can survive. Under optimal conditions the organism will be able to survive and reproduce. Then stops reproducing, then growing, then dies. Species with a greater tolerance are more likely to survive on the upper shore.
Competitive exclusion
Interspecific competition (must be for resources that are in limited supply) drives one species to local extension (Gause’s principal).
Fundamental Vs Realised Niche
Fundamental niche is the full range of environmental conditions a species could occupy if there were no limiting factors. In contrast, the Realised Niche is the actual niche occupied by a species, it is smaller than the fundamental niche due to limiting factors such as competition and insufficient resources.
Things to include in discussion
Zonation def + cause, 2 species with specific data and in/decrease. Link exposure to distribution. Adaptations to specific habitat (preventing desiccation / competing & hiding from predators). Competition, fundamental / Realised niche / tolerance, niche partitioning, Gause.
How must organisms adapt to deal with less water coverage.
They must adapt to be able to respire on land (I.e. Blue-banded periwinkle has adapted gills are adapted to extract oxygen from the air), and avoid desiccation (BBP clamps down shell).
How can temperature effect organisms?
Low temperature makes organisms slower to conserve energy. If temperature is so high it breaches tolerance it can put the organism under physiological stress with the potential to denaturise enzymes. High temp leads to high salinity which can cause a loss of water by osmosis, high temp also means less dissolved oxygen makes it hard to respire.
What environmental factors come with living closer to high-water mark?
Increased exposure less connection to the ocean means temperatures are more extreme (harder to heat up a larger volume of water).
What to say if the two species overlap?
They must have slightly different ecological niches, as Gause’s pricnipal suggests that if they had nearly identical ecological niches, one may eventually outcompete the other, leading to competitive exclusion, unable to coexist in the same habitat with the same ecological niche.
What to say if one species is abundant and one is not very common? (Overlap)
Both species have similar fundamental niches, which leads to a smaller Realised niche (niche partitioning) because of competition for the same resources. This is observed as X is abundant almost everywhere, while Y is not very common.
