APES Chapter 5/6

key points of the new england forest succession case study

-when pilgrims arrived in Massachusetts they found undisturbed temperate seasonal forests - maple sugar, american beech, white pine, eastern hemlock -settlers cut down most of the trees -lots of farmers left -seeds were carried over to the abandoned fields and new life formed -goldenrod's dominated the fields -this species brought many insects -created an ever changing ecosystem -finally tree seeds arrived -white pines

what three mechanisms does evolution occur?

1) Natural Selection - A, G, H 2) Genetic Drift - C, E, F 3) Gene Flow - B, D

how much of the oxygen we breathe comes from phytoplankton

50-85%

difference between a fundamental and realized niche

A fundamental niche potentially occupied by that species. A realized niche is a portion of the fundamental niche it actually occupies in a certain environment.

difference between a niche specialist and niche generalist

A generalist species is one that can live in a wide variety of habitats and have a varied diet, while specialist species are adapted to a particular environment or a specific diet. Koalas and tiger salamanders are examples of specialist species, while raccoons and mice are generalist species.

genotype

An organism's genetic makeup

phenotype

An organism's physical appearance, or visible traits.

niche

Full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions

differences between r- and K- selected species

K- Selected Species They are populations of a roughly constant size whose members have low reproductive rates. The offspring produced require extensive postnatal care until they have sufficiently matured. They are very limited in resourses therefore they are a very competitive species. Humans are examples of a k-selected species. R-Selected Species They are populations that experience rapid growth of the J-curve variety. The offspring produced are numerous, mature quite rapidly, and require very little postnatal care. Consequently, this population grows fast, reproduces quickly, and dies quickly. Bacteria are examples of r- selected species.

Why is dispersal ability important in succession?

Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have very limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors.

how are phytoplankton classified? are they plants?

Some phytoplankton are bacteria, some are protists, and most are single-celled plants

difference between community and population

The difference being that the population consists of just a signal species, and the community consists of a group of species and their interactions.

what is a dead zone and how does it form

a reduced level of oxygen in the water. Dead zones begin to form when excess nutrients, primarily nitrogen and phosphorus, enter coastal waters and help fertilize blooms of algae. Major nutrient sources include fertilizers, wastewater, and the burning of fossil fuels.

population

composed of all individuals that belong to the same species and live in a given area at a particular time

calculate population density

divide the total population of an area by the total land area.

niche vs habitat

habitat 1. It is a specific place or locality where a community resides. 2. A habitat has a number of niches. 3. Habitat supports a number of species. 4. A number of environmental variables occur in a habitat. 5. A species does not change its habitat. niche 1. It is an ecological component of habitat which is delimited by functioning of an organism. 2. A niche does not have components. 3. Niche supports a single species. 4. Niche has a specific set of environmental regimes. 5. A species may live in more than one niche in different stages of its life cycle.

challenges of a high and low density population

high population: overcrowding, reduced # of places to live, # of jobs low population: inbreeding, locating mates

density dependent

influence an individuals probability of survival and reproduction in a manner that depends on the size of the population

inputs and outputs of a population

inputs: immigration and births outputs: emigration and deaths

difficulty with limiting nutrients in waterways

nitrogen and phosphorus are the two nutrients that are a concern. a lack of these nutrients can cause algae to not grow which decreases oxygen. an increase in nitrogen and phosphorus are also bad. if there is too much algae the ecosystem cant handle it

secondary succession

occurs in areas that have been disturbed but have not lost their soil. follows an event such as a hurricane or forest fire, that removes vegetation but leaves the soil mostly intact. Secondary succession also occurs on abandoned agricultural fields

primary succession

occurs on surfaces that are initially devoid of soil, such as an abandoned parking lot, newly exposed rock left behind after a glacial retreat, or newly cooled lava. the kind of environment that eventually develops is determined by the temperature and rainfall of the region.

carrying capacity

population growth slowed as population size increased because there was a limit to how many individuals the food supplies could sustain. knowing the ____ ____ and limiting resource helps us predict how many individuals an environment can sustain. denoted as K

what are the 5 major characteristics of populations that ecologists study- and why is each important?

population size:total # of individuals within a define area at a given time population density: # if individuals per unit area (or volume, in the case of aquatic organisms) at a given time- knowing a populations density in addition to its size, can help scientists estimate whether a species is rare of abundant population distribution: a description of how individuals are distributed with respect to one another population sex ratio: ratio of males to females usually close 50:50 population age structure: description of how many individuals fit into particular age categories

differences between primary and secondary succession

primary succession occurs on surfaces with no soil so mosses, lichens, and algae. secondary succession occurs on areas that have been disturbed but have some soil. The process of primary succession starts when bare rock colonizes with algae. Secondary succession begins with the rapid colonization by plants that can easily disperse.

limiting resources

resource that a population cannot live without and occurs in quantities lower than the population would require to increase its size examples: terrestrial plant populations, water and nutrients such as nitrogen and phosphorus, food water and nest sites (for animals)

density independent

same effects of an individuals probability of survival and amount of reproduction at any population size

what is the difference between species richness and evenness?

species Richness is the number of species in a given area such as ponds, canopies of trees- gives the approximate sense of the biodiversity of a particular place species evenness tells us whether a particular ecosystem is numerically dominated by one species or whether all of its species have similar abundance

pioneer species

species ability to colonize new areas rapidly and grow well in full sunshine. As the ____ trees increase in number and grow larger, however, they start to shade one another, reducing one another growth and fitness

explain how latitude, time, and area of a community contribute to species richness

species richness increases as you move towards the equator with the length of time a population has existed, with increased habitat size, and with shorter distances from sources of colonizing species

how are boundaries of a population measured

the boundaries of a population arent exactly set or strict due to the input and outputs of a population (immigration/emigration). the boundaries are dictated by the ecologist studying the population

can two species occupy the same niche

the competitive exclusion principle, also called Gause's Principle, states that when two species compete for exactly the same resources (thus, they occupy the same niche), one is likely to be more successful.

how can a keystone species change a community

the ecosystem would be dramatically different or cease to exist altogether. All species in an ecosystem, or habitat, rely on each other.

what varies between the forest floor in a mature/climax community vs. a pioneer plot? what about the canopy?

the forest floor in a mature community would have many different species will be competing for space within the plot and for sunlight. in a pioneer plot the trees have mostly grown to their full potential, meaning the canopy is thick, so sunlight has a hard time reaching the forest floor. Pioneer plots will seem more spacious because there are less saplings and bushes on the floor.

how many mass extinctions have occurred? what mass extinction are we in the midst of and why is this one different

there have been 5 mass extinctions. we are in the midst of the 6th one. this mass extinction is happening much more quickly and it is though to be caused by natural phenomena such as shifting continents, comet or meteoroid impacts, or climate change independent of human influence, or some combination of these factors. In contrast, as we will see below, humans are causing the current mass extinction.

how many original finches were there- how did they diversify?

there were 13 species and they diversified by singing different songs and in varied appearance