Biology 106 After Exams

Under what two conditions are plants and animals more likely to produce many small offspring?

1. Plants and animals whose young have a low chance of survival often produce many small offspring. 2. The use of resources for one function (such as reproduction) can reduce the resources available for supporting another function (such as survival).

Define a population:

A population is a group of individuals of the same species living in an area. Population ecology analyzes factors that affect population size and how and why it changes through time.

Which prey defense tactic is shown by the 3 species at the bottom?

Batesian mimicry.

What are these caterpillars masquerading as?

Bird poop.

What is their role in nutrient movement?

By recycling chemical elements to producers, detritivores also play a key role in the trophic relationships of an ecosystem. Detritivores convert organic matter from all trophic levels to inorganic compounds usable by primary producers. When the detritivores excrete waste products or die, those inorganic compounds are returned to the soil. Producers can then absorb these elements and use them to synthesize organic compounds. If decomposition stopped, life as we know it would cease as detritus piled up and the supply of ingredients needed to synthesize organic matter was exhausted.

Interspecific Interactions

Competition is a −/− interaction that occurs when individuals of different species compete for a resource that limits the survival and reproduction of both individuals. Predation is a +/- interaction, with a positive effect on the survival and reproduction of members of the predator population and a negative effect on members of the prey population. Mutualism is a +/+ interaction: The survival and reproduction of individuals of each species increase in the presence of the other species. Exploitation is a +/- interaction in which individuals of one species benefit by feeding on (and thereby harming) individuals of the other species. Herbivory is a exploitative (+/−) interaction in which an organism—an herbivore—eats parts of a plant or alga, thereby harming it but usually not killing it. Parasitism is a +/− exploitative interaction in which one organism, the parasite, derives its nourishment from another organism, its host, which is harmed in the process. An interaction that benefits the individuals of one species but neither harms nor helps the individuals of the other species (+/0) is called commensalism.

What are detritivores (or decomposers)?

Consumers that get their energy from detritus or nonliving organic material, such as the remains of dead organisms, feces, and fallen leaves. Although some animals eat detritus, the most important detritivores are prokaryotes and fungi.

Which predator avoidance adaptation is shown?

Cryptic Coloration (camouflage).

What are the first multicelled organisms to colonize in primary succession?

During primary succession, the only life-forms initially present are often prokaryotes and protists. Lichens and mosses, which grow from windblown spores, are commonly the first macroscopic photo-synthesizers to colonize such areas.

List the six density-dependent regulation mechanisms mentioned in this paragraph:

Energy, shelter, refuge from predators, nutrient availability, water, and suitable nesting sites can all be limiting factors.

What does extra investment by the parents accomplish for the offspring?

Extra investment on the part of the parent greatly increases the offspring's chance of survival.

List the three ways ingested food is partitioned by the caterpillar:

Feces, cellular respiration, and growth (new biomass; secondary production).

In this food web, what is the highest trophic level of the hawk?

Fifth-level Consumer

All of the following are density dependent factors except one. Which one is not?

Flooding.

Where do plants get the carbon to make glucose?

From the atmosphere.

What do plants and other photosynthetic organisms convert solar energy into?

It is converted to chemical energy.

Some energy is always lost. What is it lost as?

It is lost as a chemical element and some elements return to the atmosphere as gases, while others are carried out of the ecosystem by moving water or by wind. Some lost as heat.

Which trait package would an r-selected species have for clutch size + size of offspring?

Large clutch size + small offspring.

Which plants house N-fixing bacteria in special nodules in their roots?

Legumes.

How do predators use mimicry?

Many predators also use mimicry. The alligator snapping turtle has a tongue that resembles a wriggling worm, which is used to lure small fish. Any fish that tries to eat the "bait" is itself quickly consumed as the turtle's strong jaws snap closed.

Which species typically colonize next?

Once soil is present, the lichens and mosses are usually overgrown by grasses, shrubs, and trees that sprout from seeds blown in from nearby areas or carried in by animals. Eventually, an area is colonized by plants that become the community's dominant form of vegetation.

How much of the original energy eaten by the caterpillar ends up as new tissues which are then available for the next trophic level to gain access to?

Only about 33 J out of 200 J, or one-sixth of the potential energy in the leaf, is used for secondary production, or growth. Only the chemical energy stored by herbivores as biomass, through growth or the production of offspring, is available as food to secondary consumers.

What trophic level do herbivores occupy?

Primary Consumer.

What trophic level do plants occupy?

Producers.

Under what conditions would you expect to find K-selected organisms?

Selection for traits that are advantageous at high densities is known as K-selection.

Under what conditions would you expect to find r-selected organisms?

Selection for traits that maximize reproductive success in uncrowded environments (low densities) is called r-selection.

Which trait package would an r-selected species have for body size + maturation time?

Small body + fast maturation.

How does an element become limited in a given system?

The balance between inputs and outputs is important because it determines whether an ecosystem stores or loses a given element. In particular, if a nutrient's outputs exceed its inputs, that nutrient will eventually limit production in that ecosystem.

Once the community reaches the climax stage, what happens next?

The climax community will continue to experience disturbances over time.check.

What is ecological succession?

The disturbed area may be colonized by a variety of species, which are gradually replaced by other species, which are in turn replaced by still other species.

What is "carrying capacity"?

The maximum population size that a particular environment can sustain; symbolized by K

What role does decomposition play in biogeochemical cycling?

The organisms that occupy the decomposer trophic level of the food web on Earth are vital to the existence of life on the planet. Bacteria, fungi and worms take the dead and decaying material and break it down (decomposition) so that the components can be recycled through the biogeochemical cycles.

List the four factors that determine population growth:

The population will increase in size with every birth and with the immigration of individuals from other populations, and it will decrease in size with every death and with the emigration of individuals out of the population.

What traits are part of the trade-offs between survival and reproduction? List them:

The traits that affect an organism's schedule of reproduction and survival make up its life history. Examples of such life history traits include when reproduction begins, how often the organism reproduces, and the number and size of offspring produced per reproductive episode.

List the trophic levels in a food chain:

The transfer of food energy from its source in plants and other autotrophs (primary producers) through herbivores (primary consumers) to carnivores (secondary, tertiary, and quaternary consumers) and eventually to decomposers is referred to as a food chain. Primary producers --> Primary consumers --> Secondary consumers --> Tertiary consumers --> Quaternary consumers

Potential prey animals have adaptations that reduce the chance of being eaten. List all of the behavioral adaptations discussed:

These adaptations include... ❖ Behavioral defenses such as hiding, fleeing, and forming herds or schools. ❖ Active self-defense is less common, though some large grazing mammals vigorously defend their young from predators such as lions.

Trophic efficiency: In general, how much energy is lost each time it is transferred from one trophic level to the next? _______ %

Trophic efficiencies range from roughly 5% to 20% in different ecosystems, but on average are only about 10%. 1% available to next level.

In a terrestrial ecosystem, how does carbon move from the atmosphere into the biosphere?

Via photosynthesis.

How does carbon move from the biosphere into the atmosphere?

Via respiration.

Distinguish between primary succession and secondary succession:

When this process begins in a virtually lifeless area, such as on a new volcanic island or on the rubble (moraine) left by a retreating glacier, it is called primary succession. Another type of succession, secondary succession, involves the recolonization of an area after a major disturbance has removed most but not all of the organisms in a community, as in Yellowstone following the 1988 fires.

What is the shape of a growth curve for a population experiencing exponential growth?

a J-shaped growth curve

Contrast these two important roles in community structure:

a. A dominant species is: a plant, animal or functional group of different species most commonly or conspicuously found in a particular ecosystem. It is generally the most populous species or comprises the greatest biomass in an ecosystem. b. A keystone species is: are not usually abundant in a community. They exert strong control on community structure not by numerical might but by their pivotal ecological roles.

For each term below, indicate the trophic level it represents:

a. Autotrophs --> The trophic level that ultimately supports all others consists of autotrophs, also called the primary producers of the ecosystem. Most autotrophs are photosynthetic organisms that use light energy to synthesize sugars and other organic compounds, which they use as fuel for cellular respiration and as building material for growth. The most common autotrophs are plants, algae, and photosynthetic prokaryotes, although chemosynthetic prokaryotes are the primary producers in ecosystems such as deep-sea hydrothermal vents and places deep underground or beneath ice. b. Herbivores --> Herbivores, which eat plants and other primary producers, are primary consumers. c. Carnivores (give two trophic levels) --> Carnivores that eat herbivores are secondary consumers, and carnivores that eat other carnivores are tertiary consumers.

Consider morphological and physiological adaptations for predator avoidance. Define the following defensive adaptations for avoiding predation:

a. Cryptic coloration: or camouflage, makes prey difficult to see. b. Aposematic coloration: or warning coloration, such as that of poison dart frogs. Such coloration seems to be adaptive because predators often avoid brightly colored prey. c. Batesian mimicry: a palatable or harmless species mimics an unpalatable or harmful species to which it is not closely related. The larva of the hawkmoth Hemeroplanes ornatus puffs up its head and thorax when disturbed, looking like the head of a small venomous snake. In this case, the mimicry even involves behavior; the larva weaves its head back and forth and hisses like a snake. In Batesian mimicry, the resemblance of a prey species to a distantly related unpalatable or harmful species is thought to have resulted from natural selection.

For each of the feeding adaptations listed, explain how it helps the predator obtain its prey:

a. acute senses: acute senses that enable them to find and identify potential prey. (ex. a pair of heat-sensing organs located between their eyes and nostrils) b. claws, fangs or poison: help them catch and subdue their food. c. speed & agility: Predators that pursue their prey are generally fast and agile, whereas those that lie in ambush are often disguised in their environments.

Factors that limit the growth of populations more strongly at high densities than at low densities are...

density dependent factors