Community Ecology Flashcards
Community definition
A set of populations living close enough for actual or potential interaction, these can be direct and/or indirect interactions.
Interspecific interactions
The interactions between species in a community
Interaction types
Competition, predation, herbivory, parasitism, mutualism
Competition
Two or more species competing for the same limited resource. The resource limits survival and reproduction of both individuals. Competition has a negative impact on both/all species.
Two species competing for the same limiting resources cannot coexist permanently in the same place. Competition doesnt always lead to extinction.
Ecological Niches
The set of biotic and abiotic resources that a species uses in its environment.
Examples include:
Tolerances eg temp, salinity
Habitat eg substrate on which it grows
Resource requirements eg type and size of prey it eats
Resource partitioning
Niche differentiation means competition is reduced
Resource part can arise from evolution by natural selection - leading to 1 species using a different set of resources
Character displacement
the indirect evidence of the effects of competition.
Tendency for charateristics to diverge more in sympatric than allopatric populations of 2 species.
Closely related species are more similar to each other when they occur in isolation than when they occur together
Allopatric and Sympatric populations
Allopatric - geographically separate
Sympatric - geographically overlapping
The allopatric populations are morphologicaly similar and use similar resources.
The sympatric populations show differences in morphology and resource use – would otherwise potentially compete.
Predation
Predator species kills and eats a prey species. Eating and avoiding being eaten are prerequisites for reproductive success.
Therefore adaptations of predators and prey are refined through natural selection.
Adaptations of predators
Sensory apparatus - Forward facing eyes, heightened visual and auditory acuity, heat sensing organs.
Catching killing and subduing prey - Claws, teeth/fangs/beaks, Stings, Poisons, Behaviours, webs/trap.
Adaptations of prey
Behavioural adaptations - Fleeing, Group living, Self defence, Group defence, hiding.
Morphological/physiologicl adaptations - Swift and agile, horns and spines, noxious secretions, bright colours, autotomy.
Colour adaptations -
Crypsis colouration makes prey difficult to see.
Aposematic (warning) colouration/signalling – predators avoid bright colours.
Batesian mimicry
Palatable or harmless species mimics an unpalatable or dangerous species. Evolves via natural selection.
Mullarian mimicry
Two or more unpalatable species mimic each other.
Shares the cost of predation as predators learn avoidance – the more unpalatable prey there are, the faster predators learn to avoid prey with that appearance.
the herbivory interaction
+for herbivore -for plant/algae
Herbivory is usually non lethal as the herbivore only eats parts of the plant/algae
Different herbivores generate different effects
This is interaction is very important because any complex food web requires organisms that can access the resources captured by primary consumers
Herbivory interaction effect on plants
It depends on the timing of the attack relative to plant development (if herbivore ate a freshly growing plant it would die but if it ate leaves on a tree it wouldn’t have as big of an effect)
Plant usually remains alive in the short term
Effect also dependant on the response of the plant
