Chapter 46 – lecture 11
- Batesian mimicry- when a platable or harmless species resembles an unplatable or poisonous
- Mullarian mimicry- involves two or more unplatable species looking the same, to teach
predators to stay away.
Predation Parasitism (+/-)
- Live off of and get nourishment from a host.
Direct contact between two species, negatively interfere with the host.
Take resources, and redouce the characteristics of survival and reproduction of host.
- Ecto: Live on surface of host (lice and ticks)
- Endo: live within the host (tick worms and nimotoads).
- An interaction where individuals use the same limited resources, where there is a greater
demand than supply for the resource.
- Interspecific Competition: competition between individuals of different species.
- Intraspecific competition: competition between individuals of the same species.
- Conditions and resources required for a species’ survival.
Conditions are abiotic non-consumable elements ex: temperature, pH, humidity etc..
Resources are consumable requirements in an environment.
- A niche, is a species’ functional role in an ecosystem.
- Competitors exclusion principal states that two species with the same niche cannot co-exist.
Most competition is asymmetrical, aka, one species is the superior competitor, and will
- Fundamental niche: the range of conditions and resources that a species can occupy in the
absence of competition. - Realized niche: the range of conditions and resources that a species occupies when there is
If competitive exclusion, why co-existence?
- Resource Partitioning
To minimize interspecific competition, species evolve and adapt into specialized niches
to minimize overlap of niches with other species. They use the same resources in
different ways, so they won’t compete.
Involves specialized adaptations.
- Character Displacement
Can be evident when competing species that are sometimes sympatric and sometimes
allopatric. Allopatric populations of some animal species are morphologically similar,
whereas sympatric species are morphologically different and use different resources.
Differences between sympatric species allow them to coexist without having them
- Both interacting species benefit from the interaction.
- Two types:
Obligate: where one species cannot live without the other.
Humans are obligate mutualisms with bacteria, we cannot survive without
Facultative: both species benefit from their interactions, but can live without it.
- Mutualism where two species are in physical contact with each other is called symbiosis.
Ex: Mycorrhizae- plant roots and fungi.
- Mutualism where two species are not in physical contact with each other is called asymbiosis.
- Where one species benefits from the interaction and the other species is not affected.
Trophic Structure: describe the abilities or interactions of species in an ecosystem.
- Primary producers: they are eaten, do not eat.
- Primary consumers (first group that eats primary consumers (ex: zoo plankton).
- Secondary consumers, then tertiary consumers, lastly quaternary consumers.
- At every trophic level, you have detritivores, to consume or break down any metabolic waste
left by all of the other trophic levels.
Very important in all trophic levels.
Limits on Foodchain Length - Energetic Hypothesis: based on the idea that you only start out on primary producer biomass,
and is reduced to 10% when it is eaten, then 10% when eaten by a carnivore, etc…. limits the
number of lengths in a food chain since not much energy as it goes up each trophic level.
- Dynamic Stability Hypothesis: population fluctuations at lower trophic levels are much more
magnified at higher trophic levels.
If you have a set amount of plants producing biomass for higher trophic levels, if there is
a catastrophic event that reduces the amount of biomass, has a much higher effect on
what will happen higher up on the food chain.
Because of this instability, there are always limits on the upper food chain.
- Dominant species are those that are the most abundant or have the highest biomass in a
community, and they exert a lot of influence over the occurrence and distribution of a lot of
other species in a community.
- Keystone species play a large role in determining what other species are present. Removal of a
keystone species may result in a large effect of abundance and distribution of the rest of the