ENVS 1126 MINI-EXAM 2 REVIEW
The risk of introducing a natural enemy to control an invasive species is that
the natural enemy might also become an invasive pest.
Despite the loss of grasses in African savannahs resulting from competition from the invasive Sodom apple, elephants may help restore savannah communities because
they eat the Sodom apple preferentially, which is toxic to most other species.
We would expect populations in undisturbed natural communities with high biodiversity
to be near their carrying capacity.
The evolution of a new species is most like
remodeling an old home into a new one.
Which of the following is analogous to a mutualistic relationship?
A basketball player is paid by a company to wear its particular brand of shoes.
Which of the following represents a type of mutualism?
A honeybee feeds on nectar at a flower on an orange tree and pollinates the flower.
Without human intervention to save a species from extinction, which one of the following organisms would be most likely to survive threats to its extinction?
A mushroom species that releases millions of airborne spores and dies
If the climate of an environment is rapidly changing, which one of the following organisms would most likely go extinct?
A species of fish that only reproduces asexually
Which one of the following is the best analogy to the movements of continents by plate tectonics?
Air mattresses drifting about on the top of a swimming pool Noodles drifting throughout a cup of chicken noodle soup
Use the following information to answer the question(s) below. In North America, a toxic weed called leafy spurge was accidentally introduced and has grown and spread rapidly, covering millions of acres in north central United States and south central Canada. Leafy spurge is generally avoided by cattle and horses and may be toxic to them. Thus, rangeland where leafy spurge has spread has been damaged by the invasion of this plant. Many strategies have been used to control leafy spurge, including the deliberate introduction of different species of flea beetles that feed on leafy spurge. Each flea beetle female may lay about 200 eggs in her one-year life span. In places where flea beetle introductions have quickly established large populations that have grown and stabilized, the population growth of these beetles most likely looked like which of these on a graph?
An S-shaped curve
Which one of the following illustrates interspecific competition?
Caterpillars of two different species of moth are feeding on the same plant's leaves.
Darwin and Wallace discovered natural selection without knowledge of an important field of biology that is very much a part of biological evolution. What essential part of biological evolution was poorly understood when they first presented natural selection to the world?
Genetics and DNA
Which of the following represents a type of top-down regulation for wildflowers living in a forest?
Herbivores in the region
In a mature forest in a national park, maple trees grow very large and live more than 80 years. Over an average lifetime, a tree produces more than 100,000 seeds, of which only 2 to 3 sprout and grow to maturity. This maple tree is
K-selected and exhibits a type III survivorship curve
The Ivory-Billed Woodpecker, long thought extinct, may have been found in deep woods of Missouri. Even though a few individuals may have survived, this may not be enough to avoid extinction of this species. What else must these few birds do to ensure the survival of the species?
Maintain a viable breeding colony in the face of environmental resistance factors
Which of the following illustrates intraspecific competition?
Male red-winged blackbirds defending limited nesting sites from other males
Which of the following organisms is most likely a K-strategist?
Oak trees
In logistic growth (an S-shaped curve), how does population growth change as the population nears its carrying capacity?
Population growth decreases.
Which of the following represents a type of top-down regulation for rattlesnakes living in Arizona?
The number of snake-eating hawks and humans in the region
A squirrel population in an oak forest in Indiana is limited by hawk predators, the amount of acorns produced annually, nesting sites in the trees, and cold winter temperatures. Which of the following is an abiotic factor limiting this squirrel population?
The stress of cold winter temperatures
Which of the following about parasites is true?
They may live inside or outside of their host.
Which one of the following is characteristic of a K-selected species?
large body size
Which one of the following is a trait that increases the chances of survival for an endangered species?
Widespread distribution
The most stable predator-prey relationships typically involve
a prey species and several natural predators.
A grasshopper population in a prairie is limited in large part by the number of birds in the region. Following a terrible storm that killed many of the birds, the grasshopper population exhibits exponential growth. This happens because the grasshoppers experienced
a steady biotic potential but suddenly decreased environmental resistance.
Density-independent factors such as earthquakes and hurricanes are
abiotic factors that are not involved in maintaining a population near its equilibrium.
In its broadest sense, fitness reflects the ability to respond to
all factors of environmental resistance
Walking through a national park, you step off a well-marked trail to take a photograph and accidentally trample a rare orchid. This is an example of
amensalism.
Threatened and endangered species receive special protection from human activities such as hunting and habitat destruction because these activities may continue despite the species' low numbers. These human activities therefore
are density independent.
In North America, a toxic weed called leafy spurge was accidentally introduced and has grown and spread rapidly, covering millions of acres in north central United States and south central Canada. Leafy spurge is generally avoided by cattle and horses and may be toxic to them. Thus, rangeland where leafy spurge has spread has been damaged by the invasion of this plant. Flea beetles alone are unlikely to eliminate all of the leafy spurge in a region. Instead, the number of leafy spurge plants and the number of flea beetles in a particular community may stabilize. At this point, the leafy spurge and flea beetle populations
are experiencing environmental resistance.
The population of game fish in a lake is under heavy fishing pressure. If too many fish are caught, the population will crash and future years of fishing will suffer. The game fish can exhibit logistic growth under certain circumstances. Assuming logistic growth, it would be best to manage this game fish population by permitting the harvesting of just enough fish to keep the game fish population
at half its carrying capacity.
When a single species evolves into two species, the new species must
be reproductively isolated.
Introduced alien species that cause the most harm are those that
become invasive.
A stable population would remain at equilibrium if
births and deaths increased by the same quantity.
Brown-headed Cowbirds lay their eggs in other birds' nests, relying upon another species to raise their chicks. Although many species continue to raise the cowbird chicks, some species reject the eggs and offspring. Further, Brown-headed Cowbirds are rare inside large forests. Which of the following represents an adaptation in response to this cowbird threat?
breeding birds of other species nesting in deep forests
Two species have separate ranges but use the same food resources. However, their ranges overlap in one area. It is found in the area of overlap that the species have evolved separate anatomical specializations that reduce interspecific competition for food. This is an example of
character displacement.
On Earth today, mountains such as the Himalayas are rising because of
collisions between tectonic plates.
Along the shoreline of a pond, Canadian geese, American toads, and grass frogs search for food while bluegill and bass prey on small fish in the shallow water. These species, living and feeding in this particular location, represent one
community.
In an ecosystem with many similar species, we typically find
competitors using different resources to minimize interspecific competition.
Sumatran rhino populations have declined steadily to a point near extinction. Because of its population decline, this unusual forest-dwelling rhino is near its
critical number and is officially listed as endangered.
The introduction of invasive North American ctenophores into the Black Sea and the Sea of Azov has
decimated fisheries because the invasive species competes for food with commercial fish species
A population of catfish in a muddy pond reaches its maximum size as the food supplies start to run low. Without any new sources of food, the catfish population remains steady. This population represents
density-dependent logistic growth.
In short, different selective pressures in closely related species will produce
different adaptations.
In North America, a toxic weed called leafy spurge was accidentally introduced and has grown and spread rapidly, covering millions of acres in north central United States and south central Canada. Leafy spurge is generally avoided by cattle and horses and may be toxic to them. Thus, rangeland where leafy spurge has spread has been damaged by the invasion of this plant. Leafy spurge has spread completely across many U.S. states. If left uncontrolled in these states, leafy spurge populations will
encounter environmental resistance factors and eventually reach their carrying capacity.
A squirrel population in an oak forest in Indiana is limited by hawk predators, the amount of acorns produced annually, nesting sites in the trees, and cold winter temperatures. The many factors listed above that can affect the squirrel population represent
environmental resistance.
The various Galápagos finch species
evolved from a single ancestral species that flew to the Galápagos Islands.
In North America, a toxic weed called leafy spurge was accidentally introduced and has grown and spread rapidly, covering millions of acres in north central United States and south central Canada. Leafy spurge is generally avoided by cattle and horses and may be toxic to them. Thus, rangeland where leafy spurge has spread has been damaged by the invasion of this plant. Plants such as leafy spurge can double their population size every year in part because of their efficient production of large amounts of seeds. Populations that can double every year, such as leafy spurge,
exhibit exponential growth as they spread to new regions.
Some beetles escape from a ship and fly to a small island covered with grass but with no trees or beetle predators. As the beetles feed, they destroy all the grasses. But with abundant food, the beetle population soars, doubling in size every month. After about a year, the population crashes as thousands of beetles have destroyed almost all of the plants and there is little left to feed the large population. This scenario best illustrates
exponential growth followed by a population crash.
Introduced invasive species are a growing problem primarily because of
global trade and travel.
A keystone species
has a disproportionately large impact on the stability of an ecosystem.
Atlantic ctenophores in the Sea of Azov and the kudzu vine overgrowing a forest in southern Alabama
have become invasive species that threaten native species in their new environments.
A population would be expected to grow if
immigration increased and deaths and emigration decreased.
In general, it is rare for a parasite to
kill its host.
Dung beetles live in regions where cattle graze, quickly burying and recycling cattle droppings. Because of the dung beetle's activities, breeding habitats and resources for disease-carrying flies are reduced and the plants upon which cattle feed are nourished. The relationship between the dung beetles and the disease-carrying flies is a type of
interspecific competition.
Over the last 100 years, the number of elk in Yellowstone has varied in part because of the limited availability of winter food sources and many types of predators, including wolves (eliminated in 1926 and reintroduced in 1995), grizzly bears, coyotes, black bears, and golden eagles. The relationships among elk predators represent
interspecific competition.
Kudzu vine, chestnut blight, fire ants, and Japanese beetles are all examples of
invasive species.
A population that is at equilibrium
is staying at about the same size.
Many wasps and bees have an hourglass-shaped body with prominent striping. Most also have a sting that they use for defense and/or for capturing prey. Tropical entomologists have long known that there are many other species of insects that lack a sting, such as flies, moths and beetles, that are remarkable mimics of bees and wasps. The mimics probably arose through
long and slow modification through natural selection.
The unusual organisms living in Australia have evolved primarily because of
long term isolation of the continent.
A population of bullfrogs in a pond produces many thousands of eggs each spring that hatch out into tadpoles. However, only about 1% of the tadpoles survive to reproduce. This population of frogs is experiencing
low levels of recruitment.
New genetic traits upon which natural selection can act usually arise from
mutations and crossover.
Dung beetles live in regions where cattle graze, quickly burying and recycling cattle droppings. Because of the dung beetle's activities, breeding habitats and resources for disease-carrying flies are reduced and the plants upon which cattle feed are nourished. The relationship between the dung beetles and the cattle is a type of
mutualism.
Genetic diversity in a species does not arise from
need or want.
Adaptation takes place in response to
only the selective pressures they experience.
Groups of organisms that may have been separated for millions of years may be brought together in new combinations primarily by
plate tectonics.
Many predator-prey relationships do not result in the complete elimination of the prey because
predators cannot catch all of the healthy adults.
Resource partitioning
reduces interspecific competition and increases species diversity.
Territoriality
reduces intraspecific fighting and ensures adequate resources for some members of a species.
Over the last 100 years, the number of elk in Yellowstone has varied in part because of the limited availability of winter food sources and many types of predators, including wolves (eliminated in 1926 and reintroduced in 1995), grizzly bears, coyotes, black bears, and golden eagles. The population of elk in Yellowstone
reflects top-down and bottom-up population regulation.
A prairie grass may experience grazing herbivores, wildfires, droughts, deep snow, or blazing hot days in the summer. Yet, those prairie grasses alive today are descendants of those that have survived these challenges and more. From an evolutionary perspective, these sorts of environmental challenges are identified as
selective pressures.
Newly formed species typically have experienced different
selective pressures.
If organisms are unable to generate enough genetic diversity to survive in a changing environment, they
sometimes go extinct.
Competitive exclusion is not as common as many biologists expected, in large part because
subtly heterogeneous environments allow apparent competitors to occupy separate niches.
The concept of biological fitness is based on two separate abilities. These are the ability to
survive and reproduce.
The reindeer population changes on St. Matthew Island appears to have ultimately been caused by
the absence of any predators.
It is common to hear about the huge reproductive potential of some organisms. For example, if all of the eggs of houseflies were to survive to maturity, the world would soon be covered in flies. This scenario does not happen on Earth because
the biotic potential would be limited by environmental resistance.
In an ecosystem, the elimination of one new species by another because of direct competition for the same resources is an example of
the competitive exclusion principle.
Controlling the Spotted Knapweed reveals
the complex set of relationships in ecosystems can produce unanticipated consequences.
Invasive species are dangerous because
the native species have not evolved with and adapted to these new organisms.
The relationship between the moose and wolf populations on Isle Royale reveals
top-down and bottom-up population regulation.
In general, K-strategists have a
type I survivorship pattern, and r-strategists have a type III survivorship pattern.
Elephant species are declining throughout their range. Factors contributing to their decline include all of the following except
viral and bacterial infections.
Some biologists have identified symbiotic relationships in which it appears that one organism gains from the relationship while the other organism is unaffected. Although after further research, the researchers find out that both members of the relationship benefit. The researchers therefore realize that
what they at first thought was an example of commensalism is really an example of mutualism.
