Lecture 21 Flashcards
What is a Community?
Association of populations of different species that live and interact in the same place at the same time
There are 7 different types of interactions, name all 7 with (+ or - / + or -)
1) Competition (-/-)
2) Predation (+/-)
3) Herbivory (+/-)
4) Parasitism (+/-)
5) Disease (+/-)
6) Mutualism (+/+)
7) Commensalism (+/0)
What is interspecific competition?
Competition between different species for a resource
What does strong competition lead to?
leads to competitive exclusion
What is competitive exclusion?
The local elimination of one species due to strong competition.
What is the ecological niche?
total use of biotic and abiotic resources by an organism.
Give an example of a species niche
Warm temperatures, medium-sized insects, dry arid environment
What does the ecological niche represent?
The set of optimal conditions for a species
Do different niches always complement each other?
No, there is usually some overlap
What is the Competitive Exclusion Principle?
Two species can’t coexist if their niches are identical.
When does coexistence happen according to the Competitive Exclusion Principle?
When niche overlap is reduced
What are the 2 types of Niches?
- Fundamental niche
- Realized niche
What is the fundamental niche?
Potential niche for an organism in the ABSENCE of competition
What is the realized niche?
The niche that an organism actually occupies in the PRESENCE of competition.
Who conducted the first experiments demonstrating the effect of competition on fundamental and realized niches?
Gause
What species were used in Gause’s experiments?
Two species of Paramecium
What are the 2 species of Paramecium
P. aurelia and P. caudataum
Why did competitive exclusion occur in Gause’s experiments?
oth Paramecium species had the same or very similar niches
How can ecologically similar species coexist in a community?
If there are significant differences in their niches, such as one species being unable to use or colonize other niches.
What is resource partitioning?
Differentiation of niches enabling similar species to coexist
How does resource partitioning facilitate coexistence?
By allowing species to occupy different niches
Give an example of resource partitioning
A. insolitus perches on shady branches while A. distichus perches on sunny surfaces like fence posts
What is character displacement?
evolution of slightly different niches by competing species to reduce interspecific competition
How do Darwin’s finches exemplify character displacement?
Competing species evolve different niches to avoid competition
What happens to niche differences when two species live together compared to when they live apart? (2)
Niche differences are greater with less overlap when they live together and less divergent with more overlap when they live apart.
The tendency for characteristics to be more divergent in (sympatric or allopatric) populations sympatric of two species?
sympatric populations
NEXT interaction: Predation (+/-)
What is predation?
interaction where one species kills and eats another
Name some feeding adaptations of predators (5)
Claws, teeth, fangs, stingers, and poison.
What are some defensive adaptations of prey? (3)
Hiding, running, camouflage.
How does natural selection affect predators and prey?
Shapes their body forms and behaviors.
What is the main predator strategy?
CAMOUFLAGE
(predators are camouflaged TO avoid notice by their prey; others may attract their prey)
What are some prey strategies?
- flee, hide, live in groups,
- mechanical defenses,
- special coloration
- use mimicry to avoid being preyed upon
What are the 2 types of prey strategies related with coloration?
Aposematic & Cryptic coloration
What is Cryptic coloration?
Camouflage that makes prey hard to see (blends in seamlessly)
What is Aposematic coloration?
Warning Coloration
Why warning coloration?
predators tend to avoid prey with bright coloration b/c it signifies chemical defenses (toxins)
What are the 2 types of prey strategies related with mimicry?
Batesian and Mullerian Mimicry
What is Batesian Mimicry?
A palatable or harmless species mimics an unpalatable or harmful model
What is Mullerian Mimicry?
Two or more unpalatable species resemble each other
NEXT interaction: Herbivory (+/-)
What is herbivory?
The process in which an herbivore eats parts of a plant.
How has herbivory influenced plant evolution?
It has led to the development of mechanical (spines, tough leaves) and chemical defenses
What adaptations have herbivores developed in response to plant defenses?
they have evolved mechanisms to counteract or tolerate plant defenses
Give an example of a plant with chemical defenses against herbivory.
Milkweeds produce chemicals that are poisonous to most insects
NEXT interaction: Parastism (+/-)
What is Parasitism?
the parasite derives its nourishment from another organism, its host, which is harmed in the process
How are mites living in the trachea of honeybees an example of parasitism?
mites clog airways = eventually kills honeybees
NEXT interaction: Mutualism (+/+)
What is Mutualism?
Interspecific interaction benefiting both species
Give a few examples of Mutualism
- Coral with zooxanthellae & polyp
- Mycorrhizae: plant & fungus
- Cleaner Wrasse & Sea Bass
- Rhizobium & legume plants
NEXT interaction: Commensalism (+/0)
What is Commensalism?
One species benefits and the other is NOT
affected
Give an example of commensalism
Crab & sea anemones
In interspecific interactions and adaptation, What is coevolution?
Reciprocal evolutionary adaptations of two interacting species
Give an example of coevolution.
The evolution of narrow deep flowers selects for the evolution of birds with long beaks for food, and vice versa for pollination.
What are keystone species?
Species that, despite not being the most abundant, play critical ecological roles.
Define dominant species.
the species with the most biomass
Dominant Species can exert control over what? (2)
capable of exerting control over the occurrence and distribution of other species.
Why are food webs more accurate than food chains in describing community interactions?
Because they illustrate the complex interactions between multiple species, whereas food chains represent only linear relationships between one species feeding on another
What is ecological succession?
What is ecological succession?
What does ecological succession involve?
It involves the transition in species composition in disturbed areas over ecological time.
What is primary succession?
type of succession that begins in a lifeless area where soil has not yet formed
Where does primary succession occur?
volcanic islands or moraines left behind as glaciers retreat.
What organisms are initially present in primary succession?
only autotrophic prokaryotes
What happens after autotrophic prokaryotes in primary succession?
Mosses and lichens colonize
What do mosses and lichen cause?
cause the development of soil
Which organisms colonize after autotrophic prokaryotes in primary succession?
Grasses, shrubs, and trees sprout
How do grasses, shrubs, and trees establish themselves in primary succession?
They sprout from seeds blown or carried into the area
What is secondary succession?
It occurs where an existing community has been removed by a disturbance such as a clear-cut or fire, while the soil is left intact.
What type of species typically grow first in secondary succession?
Herbaceous species grow first
Herbaceous species grow first from WHAT? (2)
from wind-blown or animal-borne seeds.
What replaces the herbaceous species in secondary succession?
Woody shrubs
What comes after woody shrubs in secondary succession?
forest trees
What is the stable final stage of succession called?
the climax community
How can a climax community be disturbed?
disturbances = fire
What happens after a disturbance destroys a climax community?
Eventually, the climax community will reconstitute itself through succession.
Besides natural disturbances like fire and insect outbreaks, what is another factor that can affect ecological succession?
Human disturbance: activities like agriculture, logging (forest clearing), and ocean trawling.
How does human disturbance impact species diversity in communities?
typically reduces species diversity
What are some consequences of deforestation caused by human disturbance?
Deforestation -> soil erosion, which in turn leads to eutrophication and silt accumulation in surrounding bodies of water.
What are some effects of having fewer trees in an area?
less shade, higher river temperatures, adverse effects on aquatic animal life, reduced habitat for arboreal species, decreased food sources, and less carbon dioxide stored in terrestrial reservoirs.
What is nutrient pollution caused by?
Nutrient pollution (eutrophication) caused by excess inputs of nitrogen and phosphorus into wetland habitats
What does this lead to?
leads to increased algal growth and subsequent ecological imbalances.
How does soil erosion lead to nutrient enrichment of aquatic ecosystems?
Rainwater washes fertilizers into rivers and lakes.
What happens when there’s an increase in nitrate or phosphate in water bodies?
Algae growth is encouraged, forming blooms.
What is the term for excessive algal growth in water bodies?
eutrophication
How does excess algal growth affect other water plants?
It prevents sunlight from reaching them, causing them to die.
What are some consequences of algae secreting toxins?
Fish can die, and humans can be affected.
What role do bacteria play in this process?
They decompose dead plants, using up oxygen and potentially leaving the lake lifeless.
Give the (+ or -/ + or -) for each statement:
The interaction is beneficial to one species and detrimental to the other
(+/-)
Give the (+ or -/ + or -) for each statement + type of interaction: One species benefits from the interaction, and the other species is unaffected by it
Commensalism (+/0)
Give the (+ or -/ + or -) for each statement + type of interaction: The interaction is beneficial to both species
Mutualism (+/+)
Give the (+ or -/ + or -) for each statement + type of interaction: The interaction can be detrimental to both species
Competition (-/-)
