Ecosystem dynamics Flashcards
(20 cards)
The Theory of Evolution
by Natural Selection
can be used to explain periodic increases and decreases in populations and biodiversity.
The impact of abiotic factors
affect the abundance and distribution of organisms in the eco system according to the needs of the organisms (tolerance range)
The impact of abiotic factors examples
Terrestrial environments (land):
water availability, rainfall, temperature, shelter availability, climate etc.
Aquatic environments (water):
light availability, salinity (salty), dissolved oxygen
The impact of biotic factors, including predation, competition and symbiotic relationships
interactions can be beneficial, harmful or neutral for each species being discussed
Predation
when one animal species (the predator) kills and feeds on another animal (the prey)
Competition
when two or more organisms use one or more resources in common such as food, shelter, mates, social standing
Intraspecific - own species
Interspecific - different species
Competition between plants: Allelopathy
Symbiosis
two organisms live in close association with each other and the relationship is beneficial to at least one of them
Types of symbiosis include
Mutualism (both species benefit from the interaction +/+)
Commensalism (benefits one organism while not affecting the other +/0)
Parasitism (benefits one organism while harming the other +/-)
Ammensalism (harms one organism with no benefit to the other -/0)
The ecological niches occupied by species
refers to the part of the ecosystem occupied by an organism. It is the role the organism plays in the larger ecosystem
no two species can occupy the same niche, this is called the competitive exclusion principle
The Fundamental niche
the potential niche they would occupy if there was no competition
The realised niche
the actual niche due to limitations caused by other organisms.
example: Koalas
An extinction event
- species that fail to adapt to environmental changes or to compete for resources can die out.
- extinction is the death of all the members of one species
Explain a recent extinction event (ASK TEACHER)
The Tasmanian tiger:
- Once widespread on mainland Australia, then confined to Tasmania
- Hunting
- Competition with introduced species
- Habitat loss
- Population fragmentation
Palaeontological and geological evidence
Provide evidence of the history of the planet and allow explanations of current events and prediction of future ones.
- Aboriginal rock paintings
– rock structure and formation
– ice core drilling
Explain how aboriginal rock paintings provide evidence for past changes in ecosystems
- give us an idea of animal distribution (where) and abundance (total number)
- record history
- changes over time suggest climate change and species change
Rock structures and formation
iron banding:
distinct layers of sedimentary rock containing iron oxides.
As a result, this indicates that conditions on early Earth were significantly different than today, e.g. oxygen levels
Ice core drilling
when ice is formed, gas bubbles in the water and pollens in the atmosphere are trapped when the liquid is solidified.
contains information about the atmosphere at the time of solidification.
Results indicated that conditions on Earth have changed significantly.
Past and present technologies that have been used to determine
evidence for past changes
- radiometric dating
- gas analysis
Radiometric dating
a process whereby scientists determine the age in years of a fossil, rock or mineral.
the radioisotope used will depend on the object being aged as different radioisotope have significantly different half-lives
Gas analysis
gas mixtures to to determine qualitative and quantitive gas composition
(current atmosphere compared to early atmosphere)
