Ecology Exam 3 study questions

What is a realized ecological niche?

The actual subset of environment where a species is found and lives

What is the definition of competition?

Interaction between two or more individuals both requiring the same limited resource that when used or defended by one individual reduces the chance of survival or reproduction of another individual

What is intraspecific competition?

Competition between members of the same species

What is interspecific competition?

Competition between different species

What is the definition of a resource?

Something that is consumed and thus reduced

What is a limited resource?

A resource with higher demand than availability

What is a limiting resource?

The most limited resource which specifically determines the population growth rate

Why does competition occur when common resources are used or defended?

Both actions prevent other organisms from accessing what they need to survive and reproduce

What is interference competition?

Direct interactions where individuals "fight" for access to limiting resources

What is exploitative competition?

Indirect competition where individuals reduce the availability of a resource by using it first

What is allelopathy?

A biological phenomenon where an organism influences the survival or reproduction of nearby organisms by releasing chemical compounds

What kind of competition is allelopathy?

Interference competition

What is an ecological niche?

A range of abiotic and biotic conditions within which individuals of a species can survive, grow, and reproduce

What is a fundamental ecological niche?

The full range of environmental conditions where a species could theoretically thrive

What are the two possible outcomes of niche overlap?

Competitive exclusion and Coexistence via Resource Partitioning

What happens in competitive exclusion?

Weaker competitor/species is driven to extinction

What is coexistence via resource partitioning?

Similar species coexisting if they share/partition the resources such that their niches no longer overlap

What is niche partitioning?

The process where competing species use different resources, areas, or times of day in an ecosystem

What are the three types of specialization in niche partitioning?

Spatial attributes, physical attributes, and temporal attributes

How does adaptive evolution result in niche partitioning?

Can result in unique changes in morphology, physiology, or behavior which allows specialization and niche partitioning

What is an example of a morphological difference due to niche partitioning in shorebirds?

Different beak lengths and shapes to specialize in different insect sizes and depths

What is a morphological difference due to niche partitioning in lizards?

Species specialize in different parts of trees and different insect sizes

What is an example of adaptations associated with frogs in niche partitioning?

Differentiation of reproduction times, thus tadpoles hatch in different months to reduce competition

Why can behavioral differentiation be caused by adaptive evolution or a learned response?

Adaptive evolution causes permanent change to the genome, and learned response is individual and can be reversed

What is character displacement?

A type of resource partitioning that occurs only where two species occur together

What is the difference between character displacement and resource partitioning?

Character displacement differs only when two species are together, while resource partitioning occurs regardless of whether species are in contact

What is the Lotka-Volterra competition model?

A modification of the logistic equation using both intraspecific and interspecific competition as a factor

How is the Lotka-Volterra competition model similar to the logistic equation?

How close the population size is to carrying capacity still determines the growth rate

How is the Lotka-Volterra competition model different from the logistic equation?

Adding individuals of another species may also bring a population closer to carrying capacity, and adding an individual from the same species affects the population growth rate differently

What does it mean if a = 1 in the Lotka-Volterra model?

Both intra- and interspecific competition have the same effect

What does it mean if a < 1 in the Lotka-Volterra model?

Intraspecific competition is greater than interspecific competition

What does it mean if a > 1 in the Lotka-Volterra model?

Interspecific competition is greater than intraspecific competition

In Lotka-Volterra, if A represents the competitive effect of sharks on dolphins, what does A = 0.5 mean?

Adding a single shark has less of an effect on dolphin population growth than adding a single dolphin

In Lotka-Volterra, if A represents the competitive effect of sharks on dolphins, what does A = 2 mean?

Adding a single shark has more of an effect on dolphin population growth rate than adding a single dolphin

What do +/- species interactions mean ecologically?

The effect of the interaction on each species' fitness

What is the effect of competition on both individuals?

Negative for both (-/-)

What is the effect of mutualism on both individuals?

Positive for both individuals (+/+)

What is the effect of predation on both individuals?

Positive for one, negative for the other (+/-)

What is the effect of herbivory on both individuals?

Positive for one, negative for the other (+/-)

What is the effect of parasites and pathogens on both individuals?

Positive for one, negative for the other (+/-)

What is the definition of a predator?

An organism that catches, kills, and consumes individuals, thereby removing them from the population

What is the definition of an herbivore?

An organism that eats plant material primarily, but does not kill the plant

What is the definition of a parasite?

An organism that consumes parts of a living organism, in or on which they live

Are predators typically larger or smaller than prey, and why?

Larger, because large prey may be impossible, dangerous, or energy-costly to subdue and consume

How can predators compensate for being smaller than prey?

Packs or persistence hunting

What is a sit-and-wait predator?

A predator that catches prey using stealth and patience instead of active pursuit

What are the 4 adaptations plants use to avoid being eaten?

Structural defenses, sticky resins, toxic compounds, and masting

How do plants use structural defenses?

Spines and tough seed coats to discourage predation

What is masting?

Synchronized mass fruit/seed production

What is plant compensation?

Increased growth upon removal of tissues, reducing herbivory effects

What is aposematic coloration?

Warning coloration that advertises toxicity

Why aren't all prey unpalatable?

Because evolving chemical defenses involves heavy trade-offs

What is Müllerian mimicry?

Noxious species evolve to resemble each other

What is Batesian mimicry?

Harmless species resembling noxious species

What are the types of Batesian mimicry?

Morphological and behavioral

How can avoiding predators have costs?

Energy expenditure and reduced foraging time can reduce growth

What are the 4 adaptations used to improve predation?

Camouflage, speed, weapons, and keen senses

What is an example of a predator adaptation with negative consequences?

Snakes that eat poisonous newts will be immobilized, and snakes with toxin resistance move slower

What is the definition of coevolution?

A series of reciprocal evolutionary adaptations in two species

What is the definition of oscillation in ecological populations?

Repetitive variation in magnitude around a central point, causing population size to fluctuate in a pattern

What causes predator and prey oscillations?

Predators eat prey (prey drops), predators starve (predators drop), prey recovers (prey rises), predator population increases

Why does the predator population lag behind prey populations?

Slower growth rate response to prey changes (delayed density dependence)

In the Lotka-Volterra predator-prey model, what do N, r, P, and a stand for?

N = number of prey, r = prey per capita exponential growth rate, P = number of predators, a = predation efficiency constant

In Lotka-Volterra for prey, what happens if P = 0?

Prey population grows exponentially because no predators remove prey

What is a zero-growth isocline?

The conditions required for a population size to stay constant

What does the prey zero-growth isocline formula P = r/a represent?

The number of predators where the prey population remains constant/stable

What does the predator zero-growth isocline formula N = m/fa represent?

The number of prey where the predator population remains constant/stable

What happens if predator population P > r/a?

Fewer prey due to higher predator population

What happens if predator population P < r/a?

More prey due to lower predator population

What happens if prey population N < m/fa?

Fewer predators due to reduced prey population

What happens if prey population N > m/fa?

More predators due to increased prey population

What combination of predator and prey sizes results in stable populations?

Only the joint equilibrium point (P = r/a and N = m/fa)

What is the definition of satiation in ecology?

Completely satisfying appetite to fullness or excess (assumed absent in standard Lotka-Volterra)

Which functional response model incorporates predator satiation?

Type II: at high prey densities, predators catch fewer prey than expected because they are full

Which functional response model incorporates low predator response at low prey densities?

Type III: at low prey densities, predators catch fewer prey than expected

How are parasites similar to predators and herbivores?

Similar to predators by feeding on a living organism; similar to herbivores by often keeping the host alive

What are macroparasites vs. microparasites?

Macroparasites are large; microparasites are small

What are ectoparasites vs. endoparasites?

Ectoparasites live on the outer body surface; endoparasites live inside the host

Are parasites pathogens?

Not all parasites cause disease, but all pathogens are considered parasites

Why do parasites represent over 50% of species on Earth?

Most are specialized for one or few host species, and most hosts harbor multiple parasite species

What is the difference between a holoparasite and a hemiparasite?

Holoparasites lack chlorophyll (cannot photosynthesize); hemiparasites possess chlorophyll (can photosynthesize)

Are holoparasites obligate or facultative?

Obligate parasites, because they cannot photosynthesize and depend entirely on the host

What is an epiphyte and is it parasitic?

A plant growing on another plant without taking nutrients; not considered parasitic

What is the basic morphology of tapeworms?

Specialized attachment organs; lack sensory organs, brain, mouth, or gut

What is the transmission cycle of Trichinella?

Host eats meat containing cysts, larvae burrow into muscles; spread by ingestion of infected muscle tissue

What is the transmission cycle of the Guinea worm?

Host consumes copepods in water, larvae burrow in gut, female blisters through skin into water to release larvae

What recent issue caused a resurgence in Guinea worm cases?

Domestic dogs becoming a new reservoir host

What is elephantiasis and how is it spread?

Severe swelling caused by filarial worms blocking lymph nodes; spread by biting insects

What is the African eye worm (Loa loa)?

Nematode larvae restricted to rainforest and swamp forests of West Africa, transmitted by flies

Why do endoparasites have complex life cycles?

They require multiple hosts, have multiple morphological stages, and may include free-living stages

What organism causes malaria?

Plasmodium (a eukaryote in the Alveolata group)

Why is developing a malaria vaccine difficult?

Plasmodium hides inside host cells and frequently alters its surface proteins

What are advantages and disadvantages of ectoparasitism?

Advantages: ease of dispersal and safety from host immune system; Disadvantages: external exposure and harder feeding

What are advantages and disadvantages of endoparasitism?

Advantages: ease of feeding and external protection; Disadvantages: host immune attacks and harder dispersal

What is a parasitoid?

A parasite whose larvae feed on host tissues, eventually killing the host

What parasitoid was used to control imported fire ants?

The humpback fly (Phorid fly)

What is host encapsulation?

A host immune defense that encloses the parasite or eggs in cells to kill them

How do some parasitoids counter host encapsulation?

Injecting a virus or specialized venom that kills the host's encapsulating immune cells

What plant was driven to near-extinction by an introduced parasite?

The American chestnut (by chestnut blight fungus)

What is a brood parasite?

An organism that manipulates another species into raising its young instead of raising them itself