Ecology - Chapter 12

Describe an example of how coevolution between a predator and a prey can led to specialization.

Like the predator-prey relationship, another common example of coevolution is the relationship between herbivore species and the plants that they consume. One example is that of the lodgepole pine seeds, which both red squirrels and crossbills eat in various regions of the Rocky Mountains. Both herbivores have different tactics for extracting the seeds from the lodgepole pinecone; the squirrels will simply gnaw through the pinecone, whereas the crossbills have specialized mandibles for extracting the seeds. Thus, in regions where red squirrels are more prevalent, the lodgepole pinecones are denser, contain fewer seeds, and have thinner scales to prevent the squirrels from obtaining the seeds. However, in regions where crossbills are more prevalent, the cones are lighter and contain thick scales, to prevent the crossbills from accessing the seeds. Thus, the lodgepole pine is concurrently coevolving with both herbivore species.

Adaptive radiation is often the result of

resource competition.

Which of the following interactions would be considered predation?

+ -

The carrying capacity for species 1 is 1000 and for its competitor, species 2, it is 500. What is the maximum abundance of species 1 if 250 of species 2 coexists with it?

500

Which of the following has the strongest impact on species 1 population size? N2 =

750.

What is the difference between a parasite and a parasitoid?

A parasitoid typically always kill its host.

What might happen over time if two bird species competed for the same seed resource and one preferred larger seeds while the other species preferred smaller ones?

Beak sizes might shift over time.

Hummingbirds are attracted to red flowers with long tubes. What might you predict would happen to flowers if hummingbirds become the predominant species on a remote island?

Flowers would become gradually more red.

________ occurs when two species undergo reciprocal evolutionary change through natural selection.

Coevolution

(T/F) An organism's realized niche is always smaller than its fundamental niche.

FALSE

(T/F) In a parasitic relationship between two species, the host species usually dies.

FALSE

(T/F) Most interspecific interactions are exclusive, involving only two species.

FALSE

(T/F) Parasitoidism is a form of mutualism.

FALSE

(T/F) The interaction between two species usually influences all individuals within the respective populations equally.

FALSE

Define a fundamental niche and a realized niche, and provide an example illustrating each. Is one always larger than the other? Explain your answer.

Fundamental niche is the entire set of conditions under which an animal (population, species) can survive and reproduce itself. Realized niche is the set of conditions used by given animal (pop, species), after interactions with other species (predation and especially competition) have been taken into account. The actual niche the species occupies is called its realized niche. Because of interspecific interactions, the realized niche of a species may be considerably smaller than its fundamental niche. The presence of the mice causes interspecific competition and means that there are fewer or no berries to eat on the forest floor. The fundamental niche of the sparrows cannot be met, so they fill the realized niche, which is the area on the bush branches only.

The concept of the niche was initially developed by

Grinnell.

Define diffuse coevolution. Do most interspecific interactions occur exclusively between two species? Provide an explanation for your answer.

In diffuse coevolution, also called guild coevolution, whole groups of species interact with other groups of species, leading to changes that cannot really be identified as examples of specific, pairwise coevolution between two species. One possible form of coevolution is cospeciation, the coordinated branching (speciation) of interacting species (such as host and parasite). ... Diffuse or guild coevolution occurs when the genetic change in at least one species affects its interaction with two or more other species.

Define adaptive radiation. Explain how it might come about using a specific example.

In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches. Adaptive radiation is the relatively fast evolution of many species from a single common ancestor. Adaptive radiation generally occurs when an organism enters a new area and different traits affect its survival. An example of adaptive radiation is the development of mammals after the extinction of dinosaurs.

An invasive bullfrog consumes a Taricha newt and dies immediately. What can you say about the toxin?

It is toxic to general vertebrate predators.

Owl species A has a carrying capacity of 2000, while another owl species B has a carrying capacity of 200. What is the logical conclusion of this?

Species B uses more resources per individual.

(T/F) Adaptive radiation can result from divergent adaptations to avoid predators.

TRUE

(T/F) Predation always has a negative effect on the individual prey.

TRUE

(T/F) Species having wide geographic distributions generally encounter a broader range of physical environmental conditions than species whose distribution is more restricted.

TRUE

(T/F) The relationship between nectar-producing flowers and nectar-feeding birds is a mutually beneficial interaction.

TRUE

(T/F) When the population size of a prey species increases, the birthrate of a predator species should also increase.

TRUE

Define five types of species interactions based on their reciprocal effects.

The five major types of species interactions are: • Competition - an interaction between organisms or species in which both the organisms and species are harmed. Limited supply of at least one resource used by both can be a factor. Competition both within and between species is an important topic in ecology, especially community ecology. • Predation - the ecological process in which an animal (or an organism) kills and feeds on another animal (or an organism). • Parasitism - a symbiosis in which one organism, the parasite, causes harm to another, the host, which the parasite utilizes as habitat and depends on for resource acquisition. • Mutualism - describes the ecological interaction between two or more species where each species has a net benefit. Mutualism is a common type of ecological interaction. • Commensalism - relationship between organisms where one organism benefits from the association while not harming the other.

A flower is not ideally matched with a pollinator that visits it daily. Why might that be?

The flower has several other pollinators with differing traits.

Calculate the growth rate of species 1 given the following information: r1 = 0.2, N1 = 1000, N2 = 1000, β = 0.5, K1 = 3000, K2 = 2000. What would it be if N1 = 2000? Why is the rate different?

Therefore, the growth rate of species 1 if N1 = 1000 is 144, and if N1 = 2000, the growth rate is 196

A species of cattail inhabits both deep and shallow water in the absence of a competitor but only shallow water in the presence of it. This is an example of

a realized niche.

The process whereby one species gives rise to several others that exploit different features of the environment is known as

adaptive radiation.

When one species reduces or adversely affects the population of another, but the affected species has no influence in return, the relationship is referred to as ________.

amensalism

An ecological niche is typically ________ dimension/s.

an unspecified number of

A food web is a better representation of a community than a food chain because most interactions among organisms

are diffuse across a range of contexts.

Mycorrhizal fungi have a mutually beneficial relationship with plants in environments with soils that

are low in nutrients.

The globeflower can host

at least six coexisting species.

The length of a butterfly tongue perfectly matches the nectar tube of a flower it pollinates. This is an example of

coevolution.

A remora feeds on the scraps that escape from a shark's mouth while feeding. It has no clear positive or negative impact on the shark. This is an example of

commensalism.

When the trunk or limb of a tree provides the substrate on which an epiphytic orchid grows, the arrangement benefits the orchid, which gets nutrients from the air and moisture from aerial roots, while the tree is unaffected. The relationship is referred to as

commensalism.

When the interaction is detrimental to the population of both species (- -), it is referred to as ________.

competition

When the relationship between two interacting species is detrimental to the populations of both species, the interaction is referred to as

competition.

As predators feed on prey, prey abundances decrease over time. This is predicted to result in a(n)

decrease in predator abundance.

The process in which a network of species undergoes reciprocal evolutionary change through natural selection is referred to as ________.

diffuse coevolution

On a dare, a student challenges another student to lick a California newt (Taricha torosa). From which population of newts should the student grab an individual to reduce his or her risk of a toxic dose?

from a population with no garter snakes

The red line in the figure (the furthest to the right) represents

highly resistant garter snake population.

In comparison to desert habitats, urban landscapes on average have a

lower number of bird species.

Urbanization impacts

most species negatively, but a few positively.

In most plant-pollinator interactions, plants species are pollinated by

multiple animal species, and each animal species pollinates multiple plant species.

When each of two species benefits from their interaction, the relationship is referred to as ________.

mutualism

Under certain conditions, ________ fungi live in the roots of many species of plants and have a mutually beneficial relationship with the plants.

mycorrhizal

When a species of bird preys upon the seeds of a plant and favors the smallest seeds,

natural selection favors individual plants that produce the largest seeds.

When individuals of two species interact, the nature of the interaction can be classified qualitatively as positive, negative, or ________.

neutral

The range of physical and chemical conditions under which each species can persist (survive and reproduce) and the array of essential resources it utilizes are referred to as its ecological ________.

niche

In an area with high soil nutrient availability, mycorrhizal fungi are

parasitic.

What does the following formula represent? dN1/dt = r1N1(1 - (N1 + N2)/K1)

population growth of species 1 in presence of species 2

As the population of a predator increases, the

population of the prey species decreases.

When one species feeds on another prey species, typically killing it, the relationship between the two interacting species is referred to as ________.

predation

The ________ niche is the portion of a fundamental niche in which species can exploit as a result of interactions with other species.

realized

Two species of cattail (Typha) live in shallow water along the shoreline of ponds. Although T. agustifolia can live by itself in water 0-20 cm deep, in the presence of T. latifolia, it occurs only in water > 20 cm deep, whereas T. latifolia occurs in shallower water. In this example, T. agustifolia is limited by competition exploiting its

realized niche.

As two competing species approach their respective carrying capacities, the growth rate of the other species

slows down.

The neurotoxin that Taricha spp. possess to ward off predators is

tetrodotoxin.

A realized niche can be larger than a fundamental niche

when a commensal species expands another's niche space.