Intro to Ecology-College level

Energy is then delegated to growth, respiration and heat.

...

Food chains are not always accurate, they tend to look at distinct, individual feeding sequences.

...

Why does each consumer level contain only about 10% of the biomass and food energy of the lower level? Where did the other 90% go? Answer: Energy is lost in 5 ways

1-Energy is used for cellular respiration. 2-Heat loss through cellular respiration which is also the 2nd Law of Thermodynamics. 3-Not all organisms are consumed. 4-Not all parts of the organism are consumed. 5-Not all parts are digestible(therefore, no energy).

Connectance is the actual number of links/potential number of links. Looking at how much overlap(interwoveness) is their in the food web.

1-Ex.-Pitcher plant community there are 19 species and 34 actual links. 2-Potential links {n(n-1)}/2 n=# of species in ecosystem Ex.- {19(19-1)/2=19(18)/2=342/2=171 3-Connectance=34/171=0.20 4-Linkage density=number of links/# of species, determines how many species consume that food source. For example the picture community has 19 species and 34 actual links. So, 1.79 result is less than 2 links per species. This tells us that there are not a lot of polyphagous species. 34/19=1.79

Rosenzweig and MacArthur(1963)

1-Prey populations may be limited by 2-Predator populations may be limited by inefficiency, so in order to survive you would need a high abundance of prey. A moderately efficient predator will lead to the 4 outcomes that Volterra/Lotka predicted. If your a really efficient predator this can become a problem because then you can drive your prey into extinction. 3-Superimpose prey and predator isoclines They said in order to understand predator and prey populations, you have to consider how efficient the predator is. Plays a role in the success of the predator.

Food chain vs. food web

A food chain is a feeding sequence at a particular time were a food web is overlapping and intersecting food chains in an entire ecosystem. A food web is also more accurate but also more complex then a food chain. Most terrestrial food chains are relatively short. Most aquatic food chains tend to be long

Fundamental niche vs. realized niche

A fundamental niche is the role a species plays in an ecosystem in the absence of interspecific competition. This is really common. A realized niche is the role a species plays in an ecosystem in the presence of interspecific competition. Competing species can therefore coexist when both are provided with a realized niche by their habitat. However, a superior competitor can deny a realized niche.

Ecosystem

All populations of organisms living and interacting in a particular area and its physical environment.

Competition

Any use or defense of a resource by one individual that reduces the availability of that resource to other individuals. Ex. space, food, mates, light and nutrients.

Chemical defenses

Aposematic coloration-A warning coloration, don't eat me ill make you sick, bite you, hurt you. Bees, yellow and black says stay away. You don't want the defense to kill the predator, but you want the predator to make that connection that your warning them and not to try to eat them again.

Tillman R*

Built upon Lotka/Volterra models. How organisms obtain and use limited resources through natural selection(more efficient) ultimately effecting distribution and abundance. He looks at the genetic variation unlike Lotka/Volterra

C.S Holey-How prey density affects predator behavior.

Came up with 3 functional responses 1-As prey density increases, the predator will just continue to eat, without becoming full. Not very likely, because they become full. Linear response-graph Like a goldfish, which will eat its self to death. 2-As prey population increases initially, predators will eat more, but eventually the prey population will level off. 3-When prey density is low the number of prey eaten is low. S pattern response-graph

Robert Payne

Coined the phrase keystone species after studying the relationship between a starfish and a mussel.

Dominant species

Difference between a keystone species and a dominant species A dominant species has a large effect in a community because it is very common Ex. Spartina is a dominant species in a salt marsh due to its large biomass and role in energy flow.

Heterotrophs

Don't produce energy, instead rely on autotrophs for energy.

Keystone habitat modifiers

Ex. Gopher tortoises Burrows provide homes for an array of mice, possums, frogs, snakes, and insects Without the burrows, many of these creatures would be unable to survive. Both gopher tortoises and beavers are considered ecosystem engineers, because they modify the habitat and cause ecological change. Humans modify are environment by building homes.

Keystone Prey

Ex. Palm nuts, figs, and nectar They are critical to tropical forest fruit-eating guilds Without the fruit trees, wholesale extinction of frugivores would occur.

Measures of food web complexity-Calculating chain length which is the average number of links per food chain.

Ex. There are 10 different food chains that have a total of 50 links. 50/10=5

Tansleys classic study

First scientist to experimentally demonstrate competition between loosely related species. Outcome-Interspecific competition is effected by resources. Did a study on plants, one that grows on acidic soil and one that grew on alkali soil. He then grew the plants(closely related) on opposite soils and the plants actually grew. He was seeing if the environmental conditions were in the range of tolerance. The next step was to see if they could grow together. The one plant outcompeted the other plant causing each to be eliminated by changing the environmental conditions ultimately effecting the abundance and distribution.

Food chain

Grass(Producer, autotroph)>Grasshopper(Primary consumer of grass, herbivore>Frog(Secondary consumer of grass, carnivore)>Snake(Tertiary consumer, secondary carnivore)>Hawk(Predator)

Paradox of enrichment

If you have a lot more nutrients thats going to support a lot more prey, leads to more producers, leads to more herbivores, then to more carnivores. Alters the outcome in either a positive or negative.

Interspecific competition

Individuals from different species striving to obtain limited resources. This is a negative/negative interaction that harms both species and can cause a decrease in reproduction, survivorship, and population dynamics. Ex. caterpillars vs. ladybugs.

Interference competition

Individuals harm one another directly by physical force. Ex. Lion and Hyenas will threaten and intimidate one another.

Intraspecific competition

Individuals of the same species striving to obtain the same limited resource. This is pretty common in nature. This is a positive/negative interaction.

Lotka/Volterra Models

Mathematical models used to describe the outcome of competition. How interspecific competition affects distribution and abundance. The mathematical equation is solving for: 1-Effects of interspecific competition. 2-Outcomes that are likely. a.Species 1 would be eliminated and species 2 would survive. b.Species 2 would be eliminated and species 1 would survive. c.Either species 1 or species 2 eliminated. The species that initially has the highest population would survive. d.Both species would coexist. 3-Defiences-Mathmatical models oversimplified because it always needs a constant, and in nature there are no constants, the only constant is that nature will change. These models only look at 2 species, doesn't take into account other species or predation.

Monophagous

Only eats one food species.

Exploitation compétition or consomptive

Organisms compete for a limiting resource without physical contact. Ex. Trees competing for water.

Overgrowth competion

Overgrowth competition occurs when an organism physically grows on top of another organism and in turn, limits the underlying organism ability to capture a resource like food or light. This type usually refers to sessile organisms.

Keystone enemies

Pisaster starfish and predatory whelks in the rocky intertidal zone Removal of either results in the community being dominated by mussels

Predator and donor control

Predator controls the abundance of prey. When the wolves were killed off, the deer population exploded. Donor control is the prey abundance controls the predator abundance, this is dependent on the amount of resources prey have. If there are little resources there will be less prey.

Benefits of predation on prey

Prey population is smaller and resources haven't changed, so this reduces competition among prey. With more resources, better survival and more reproduction. Smaller population may reduce the effects of predation from other predators cause the prey maybe the harder to find. The predators will eat the week prey, then genetically it makes the prey population stronger.

Autotrophs

Produce energy

Georgyi Gause

Species my coexist if they do not occupy identical niches. Determined competitive conclusion principle, that species with exactly the same requirements cannot live together in the same place or use the same resources(niche).

Polyphagous

Tend to eat a variety of food.

Trophic level

The expression of an organisms feeding status in an ecosystem. -Producers -Consumers(Primary, Secondary, Tertiary)

Problems with food web patterns

There are numerous problems with data that invalidate the observed patterns in food webs. 1-Predation: Minor species is frequently omitted. Food webs are far more complex than is reported. 2-Food web doesn't tell us how dependent a species is on a certain food source.

Pyramid of numbers

Top predators tend to be sparsely distributed, whereas herbivores are more common. A lot more individuals are lower on the food chain. Exceptions to the pyramid -Oak tree(one producer);supports thousands of organisms.

Allelopathy

a biological phenomenon by which an organism produces one or more biochemicals that influence the growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms.

Keystone species

a species that has an effect on an ecosystem out of proportion to its abundance or biomass Ex. The beaver can completely alter an ecosystem by building dams