Biogeography Midterm II

Niche Modeling

1. Input data -Environmental information at time 0, occurrence data, and environmental information at time 1 2. Run modeling algorith 3. Project either forward or backward in time Generally uses only two environmental input parameter and both are usually abiotic.

Biome

- A defined area of similar climate and vegetation type. May contain different taxa in different regions. -Defined by vegetation structure, leaf type, and plant denisty -Highlights the role of the physical environment in determining characteristics of species assemblages

Soil Fauna, Succession and Diversity

- The net effect of the soil community on early and mid-succession and on plant species diversity seems to be due to a selective suppression of the dominant plant species by soil fauna - Attributed to higher root quality and accessibility or to lower tolerance to herbivory of the early succession plant species - The results show that there is a strong linkage between succession in vegetation and in soil community compositio

Rapoport's Rule

-A tendency for geographic range size to increase with latitude -A tendency for geographic ranges to become less numerous and more irregular in shape from the equator to the poles

Stenophagous Predators

-Highly selective predators that only have one prey species and often have identical distributions to their prey

Issues With Niche Modeling

1) Course spatio-temporal resolution (grid size) -Single grid can encompass a lot of variation -Small patches of suitable habitat overlooked? 2) Not enough data for accurate extrapolation 3) Models don't assess vegetation types (i.e. soils, which are a critical factor)

Three Fundamental Processes in Biogeography

1) Evolution 2) Extinction 3) Dispersal These are the processes by which organisms respond to the spatial and temporal dynamics of the geographic template.

Six Forms of Terrestrial Vegetation

1) Forest 2) Woodland 3) Shrubland 4) Grassland 5) Scrub 6) Desert

Three Types of Dispersal Events

1) Jump Dispersal 2) Diffusion 3) Secular migration

Dispersal and Range Expansion

1) Must reach a new area 2) Survive the potentially harsh conditions occurring in the new area 3) Be able to reproduce in the new area to the extant that a new population is established In other words, must disperse to new regions, then evolve and adapt to the new environment or suffer extinction.

Long Distance Dispersal Consequences

1) Offers a way to explain wide and often discontinuous distribution patterns 2) Helps to account for the similarities and differences among biotas inhabiting widely separated but similar habitats 3) It emphasized the importance of anthropogenic long-distance transport of species

Two Fundamental Properties of Communities

1) Structure 2) Function

Other Freshwater Wetlands

1) Swamps 2) Marshes

Aquatic Abiotic Factors

1) Temperature 2) Pressure 3) Light 4) pH 5) Salinity 6) Oxygen concentration 7) Inorganic nutrients

Temperate Deciduous Forest

A catch all term since there is sometimes no clear division between temperate deciduous, temperate evergreen, coniferous forest, etc. Mixed forests are not uncommon. Occurs where annual precipitation is high and there is very little variation in average rainfall. Vertically stratified. Birds, mammals and insects make use of all layers from the floor to the canopy. Most important consumers are fungi and bacteria which recycle organic material. Soils are usually moist and fertile.

Contour Map

A depiction of vary density of a species. Uses interpolations between known data points. Abundance data come from census counts (number of birds seen per hour, per field part). These data are entered into a computer program where it is averaged and smoothed to estimate abundance between actual census localities. Issues include the fact that abundance is usually only available for a limited number of fairly widely separated localities, so much of the pattern is based on interpolation which can contain errors and biases of scale.

Filters

A dispersal route that exercises some selection over the types of organisms that can pass through it. Colonists are somewhat biased subsets of those that could potentially pass.

Net Primary Productivity

A measure of the rate at which solar energy is converted to plant tissue, typically express as mass produced per unit of surface area. NPP is one of the most fundamental and important measures of community function as it represents the energy available to maintain biomass and maintain the diversity of almost all forms of life.

Microcosm

A small and relatively self-contained ecosystem. A small pond is a good example of this.

Keystone Species

A species that strongly influences the community structure through its direct and indirect effects.

Deterministic View of Community (Clementsian)

A super-organism view of community, which has its own life and structure and own spatial and temporal limits. According o this view, individual organisms and species can be likened to the cells and tissues of an organism and the process of secondary succession could be likened to the growth and development of an individual. In other words, this view of community was that of a discrete and high integrated unit.

Vagility

Active dispersal. Dispersing under its own power

Temperate Shrubland and Woodland

Adapted to fires. Fires are frequent and intense, accounting for the relative lack of large trees. Sclerophyllous woodland occurs on all continents except Antarctica. Mostly in Mediterranean and W NA. Relatively moderate temperature year round. Warm dry summers, cool, moist winters. Organisms are adapted for drought. Trees and shrubs are typically evergreen with small waxy leaves. Fire-selected plants dominate.

Tamarix

Allelopathic interferer through fire adapted deep roots that limit competition from other plants by taking up salt from deep ground water and depositing that in the surface soil where it is temporarily detrimental to some plants.

Community

An assemblage of different species living together in the same place

Ecosystem

An assemblage of species inhabiting a place, but also all of the features of that place's physical environment and all of the interactions between the biotic and abiotic components of the system. There is an inherent interdependence of all ecosystems which is demonstrated by the widespread impact of human activities.

Euryhaline

Animals that are able to adapt to a wide range of salinities

Eurythermal

Animals that tolerate a wide range of temperatures

Euryphagous Herbivores

Animals that use many plant species for food

Anthropogenic Disturbance

Any disturbance that is man made is much more dangerous than natural disturbance because there is no succession/replacement of new species after the original are extinct. Damming can alter flood regimes by changing the frequency or geographic extent of flooding. The flood plains rely on periodic flooding for proper function. So this lack of flooding thank to dams can cause dry soils and vegetation change. Damming can also trap sediments and therefore not replenish downstream sandbars, which will in turn disappear. This can establish woody vegetation to grow over river banks. It will also alter water temps and clarity, effecting native aquatic species. In sum, damming can change the entire ecology of original ecosystems.

Predation

Any interaction between two species where one benefits and the other suffers. Under this definition, herbivores and their plant food are also considered predation, along with parasites and their hosts. How predation effects distribution: 1) Predators that rely on a specific prey are restricted by the distribution of that prey 2) Predators limiting the distribution of prey by killing and eating prey organisms

Second Law of Thermodynamics

As energy is converted from one for to another, its capacity to do work is diminished and entropy increases

Division of Marine Communities into Major Zones

Based primarily on water depth, light levels, and relationships between organisms and substrates. Water column is divided between photic (well-lit) and aphotic zones. Boundary is arbitrary. Essentially all organic energy that sustains marine life is produced in the shallow surface layer of the photic zone. Many organisms in the aphotic zone obtain energy by consuming organic material that is produced int he photic zone and reaches deep water in the form of sunken dead bodies.

Bergmann's Rule

Bigger animals tend to have bigger ranges

Tropical Savanna

Biomes dominated by a nearly continuous layer of xerophytic perennial grasses and sedges with scattered fire resistant trees or shrubs. They are characterized by high productivity of both grasses and grazing mammals. Most activity takes place at ground level. Drier than tropical dry forests. Soil layers have low permeability so water is retained near the surface. Maintains enough water in surface soils to support grasses in dry areas but not trees. Most savannas are strongly influenced by three common factors: seasonally intense precipitation, fire during the dry season, and migratory or seasonal grazing. These dynamic forces combine to make savanna one of the most spatially and temporally heterogeneous biomes on earth.

Facultative Mutualism

Both organisms gain a benefit from the presence of the other but each can survive without the other.

Detritivores

Break down all waste to its basic mineral components so the cycle can continue.

Secondary Consumers

Carnivores or organisms that get nutrition from animal tissues

Boreal Forest

Characterized by cool temperature and adequate moisture. Have a pattern of wood and water. Low plant diversity. Little herbaceous vegetation. Some small shrubs are common. Cool temps and waterlogged soils, decomposition rates are slow resulting in accumulation of peat, render many soil nutrients unavailable for plant growth. Long winter and short summers. Some of the most variable climates on earth. Low evaporation rates make drought rare.

Competition

Competition is a mutually detrimental interaction between individuals. Organisms that share requirements for the same essential resources compete with one another and consequently suffer reduced growth, survival, and reproduction if there is a limited resource supply. Plants compete for light, water, nutrients, pollinators, or physical space, where animals compete for food, shelter, mates, and living spaces.

Character Displacement

Darwins Finches exhibit strong selection on bill size when sympatric with a competitor. In other words, when they are not competing, they have similar bill sizes, but when together, they have discrete and different bill size ranges.

Oligotrophic Lakes

Deep, nutrient poor lakes. No turn over due to depth. High water clarity and oxygen levels, but low productivity.

Bathymetry Division

Defining communities based on the depth and configuration of the ocean bottom at which they are found. 1) Intertidal Zone where the sea meets the land 2) Neritic Zone which is over continental shelves 3) Bathyal Zone dark, cold constant, marine equivalent of a canyon 4) Abyssal Zone which is most of the ocean that has a constant dark, cold, high pressure, unchanging chemical composition environment

Distrubance

Definition: any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment. Fire, volcanism, floods, and hurricanes have great impact on species distributions by killing individuals, changing resource availability, and environmental conditions, thereby altering species interactions.

Ecological Niche

Describes the ecological space occupied by an organism in terms of resource space, environmental tolerance, and ecological role. Helps us know: 1) the main factors that limit population growth, and 2) mechanisms and factors that influence a species' geographic distribution

Decomposers

Detritivores, which are heterotophs and consist mostly of bacteria and fungi

Disjunction

Discontinuous range of a taxon in which at least two closely related populations are separated by a wide geographic distance. Two historical explanations: 1) Dispersal (long distance) 2) Geological events (ancient corridors, trans-oceanic land bridges

Corridors

Dispersal routes that allow movement of most taxa from one region to another. They do not selectively discriminate against one form but allow a balanced assemblage of plants and animals to cross. Two end should contain a fairly similar assemblage of organisms.

Sweepstakes Routes

Dispersal routes that refers to the crossing of a barrier by rare, chance events. Such events, while highly unlikely in the short term are likely over the long term. Such rare events strongly influence the geography of nature.

Biotic Exchange and Dispersal Routes

Distinguish three kinds of dispersal routes based on how they effect biotic interchange. 1) Corridors 2) Filters 3) Sweepstakes

Primary Succession

Ecological succession in an area that lack organic matter and has not been altered by living organisms. If the substrate is removed and the community must start from scratch (starting from a bare rock) Ex.: Establishment after glacial retreat or volcanic activity

Energy and Trophic LEvels

Energy is given off as heat at each trophic level so that only a portion of the energy is transferred from one level up to the next. The ecological pyramid demonstrates the transfer of energy from one level to the next with only about 10% (or less) being transferred at each level

First Law of Thermodynamics

Energy is neither created nor destroyed, but may be converted from one form into another

Mass-Specific Metabolic Need

Energy required per unit of mass are greater for small organisms than for larger ones. A mouse needs about 25 times more energy per gram of body mass than an elephant. This is probably the reason for almost all rate processes being accelerated in small organisms, which are generally more active and have higher reproductive rates and shorter life spans than large organisms.

Storage Capacities

Energy stored as fat, water volume, and mineral stores in bone tissue increase in direct proportion to mass. Therefore, all else being equal, larger organisms have greater capacities to withstand prolonged stresses such as starvation, dehydration, and subfreezing temperatures.

Taylor's Law of the Minimum

Factor or range of factors may not be continuously effective but are present only at some critical period during the organisms lifespan. Without fire, sequoia won't reproduce since they will be replaced by other conifers, so Sequoias are established in a very fire-prone climate.

Source Habitats

Favorable conditions keep birth rates high and death rates low, creating areas that act as a source for the species when the surplus individual migrate to other habitats.

Desertification

Fire suppression along with overgrazing have played a major role in the desertification and degradation of grasslands in the southern US, N Mexico, and other arid regions of the world.

Lotic

Flowing bodies of water. Springs, streams, rivers. Have rapids which are higher velocity water (high oxygen, rocky bottom). Have pools which are deeper, slower moving water (silty and poorly oxygenated).

Riparian Forest

Forests that grow thanks to increased soil moisture from floods in dry regions that otherwise can't support trees.

Peatlands

Freshwater ecosystems that develop in cool temperate areas of the N hemisphere where drainage is blocked, thus resulting in continuous saturation of soils which slows decomposition, promoting the accumulation of partially decomposed plant material called peat. Two kinds of Peatlands: 1) Bogs: from precipitation 2 )Fens: from runoff or groundwater

Hydrothermal Tube Worms

From the Galapagos Rift have a symbiotic relationship with chemosynthetic bacteria to produce organic compound necessary for life. Don't need energy from the photic zone to survive thanks to deep-sea vents with submarine hydrogen sulfide emitting hot springs

Fundamental Unit of Biogeography

Geographic range. If this is true, the real units of distribution would be the locations of all individual of a species.

Primary Consumers

Herbivores, or organisms that eat a plant-based diet.

Whitaker's Results

His coenoclines accurately reflect the random distribution of many plant species along environmental gradient, but abrupt replacements by competing species can undoubtedly occur in some cases in which ecologically similar or closely related species come into contact

Desert

Hot deserts and semi deserts occupy about 20% of the Earth's surface. Very little rain and it is unpredictable. Temperature changes on a seasonal basis. It's not always really hot and because of the extreme dryness, daily temperature fluctuations can be significant. Environmental conditions vary among deserts, but water loss through evaporation and transpiration exceed precipitation during most of the year. Plant cover is absent from many places. When it is present it is usually sparse. It's often grey/green because of waxy, protective outer layer. Have very shallow, extensive root systems which act like inverted umbrellas, capturing rainfall before it penetrates the soil. Animal abundance tends to be low but diversity can be high. Many animals are adapted to deal with the extreme environment. For example, rodents getting enough water through food rather than drinking directly. Others avoid heat stress through nocturnality or seasonal inactivity.

Soil as a Physical Limiting Factor

In gradients of increasing aridity, the limits of plant distributions are determined largely by an inability to tolerate low soil moisture.

Life Stage and Niche

In many organisms, different life stages have different fundamental niches. Ex. Pupfish adults can survive in 0-42 degrees C but eggs develop only at 20-36 degrees C. Therefore pupfish adults can be found in sink habitats where they are able to survive but reproduction is impossible

Community Function

Includes all the dynamic properties that affect energy flow and nutrient cycling, such as photosynthesis and decomposition

Dot Map

Indicate points on a map where a species has actually been recorded, which provide a very accurate depiction of the records of a species distribution. Issues are that specimen records and sightings represent only a fraction of the actual places where individuals occur, so they may seriously underrepresent distribution and abundance. They can also exaggerate current ranges if the data is old and collected over a long period of time.

Mutalisms

Interspecific interaction in which both species benefit.

Integrated Community View

Introduced the idea that facilitation is a factor that shapes plant community structure. In other words they can function simultaneously as individualistic species and different species that function interdependently

Biological Control

Introducing a non-native organism to an ecosystem and having its distribution be controlled by a single predator. This can be disasterous to local populations in certain cases like with the large mouth bass eliminating a large number of species in Lakes in the western US.

Parasites as Predators

Lampreys in the great lakes is a good example of this when they were accidentally introduced through the opening of a canal and nearly eliminated all lake trout in each of the great lakes. Internal parasites and microbes probably play a major role in limiting distributions. There are increasing numbers of examples of domesticated plants and animals that have been able to expand their ranges into previously uninhabitable areas following the elimination or control of their parasites and pathogens. The reverse is also possible, when human introduce parasites that cause range contractions. Avain Malaria in hawaii is a prime example of this

Terrestrial Biomes

Life zones, biomes, and ecoregions, have all classified terrestrial communities on the basis of structure of plants. This structure reflects the predominant influence of the climate and soil on the kind of plants that occur in a region. In other words, similar climatic regimes do tend to support structurally and functionally similar vegetation in disjunct areas of the world. Often these similarities result from convergence.

Light as a Physical Limiting Factor

Light provides the energy required for photosynthesis to occur and levels of light available directly affects the distributions of plants.

High Temperature and Oxygen Depletion

Many abiotic factors interact in important ways to limit the distributions of species. A simple example is the effect of temperature and oxygen concentration on many fish and aquatic vertebrates. As water temperature increase, its capacity to hold oxygen and other dissolved gases decreases. This can be lethal.

Fire Adapted Species

Many species in fire prone areas are adapted to withstand fires. For example, many trees possess fire resistant bark or deeper root systems. Certain species even have seeds that need to be heated to cause them to germinate, or else they remain dormant in the soil. Some trees possess serotinous cones that remain closed until they are heated by fire and can drop their seeds. The resin that keeps the cone scales closed melt at high temperatures and seeds are then released. Fire also releases nutrients from dead and living vegetation back into the soil and clears leaf litter and decaying vegetation cover. Most plants can't germinate under dense forest canopy so destruction by fire allows shade intolerant plants to regenerate and take advantage of enriched soils from the minerals in the ash

Krumholz

Means crooked timber and refers to the dwarfed nature, contorted shape, and lack of branches on the windward side of the tree at the timberline.

Distance Decay

More distant sites tend to be more different than closer sites

Multifactor Geographic Template

Most biogeographic patterns ultimately derive from the regular spatial variation in environmental conditions. Ex.: Low to high latitudes show a temperature gradient, cooling in a regular manner. Diversity and composition of environments change in a similarly regular and predictable manner.

N-Dimensional Hutchisonian Niche

Multi-dimensional space of resources that a species needs to survive and reproduce. Conceptualizes how environmental conditions limit abundance and distribution. Defined by the species that it contains, therefore in the absence of a species, the niche does not exist. Over a period of time and over its geographic distribution, every species is limited by a number of factors, in which different axes represent different environmental variable (light, nutrients, moisture, etc.). The niche of a species can thus be visualized as the combination of these variables that allow individuals to survive and reproduce and for populations to maintain their numbers. In this view there is a difference between fundamental and realized niche. Certain interactions decrease the range of resources actually used by an organism, making the realized geographic range and niche smaller than the fundamental version.

Competitive Exclusion in Appalachian Streams

Native brook trout can no longer compete with introduced rainbow trout. The native Brookies are typically found only in the upper reaches of streams that are unavailable to the rainbows.

Autotrophs vs. Heterotrophs

No living thing is so independent that its abundance and distribution are unaffected by other species. However, organisms vary greatly in the extent to which they are dependent on other organisms. Autotrophs are more independent than heterotrophs because they can make their own energy, but still require a little bit of help from bacteria, fungi and other insects and vertebrates for reproduction, etc. Hetrotrophs are less independent because they need the lower trophic organisms to harness usable energy

Aquatic Communities

Not classified into categories analogous to those used for terrestrial biomes. Hard to equate because environment in much more 3 dimensional and doesn't have a comparable plant structure. Organisms spend much or all of their lives suspended in the third dimension, drifting or swimming actively.

Gleasonian Succession

Observed impressive diversity of successional series and alternative climaxes, even for a given region and therefore succession is not an orderly process. It is rather driven by species interaction and autogenic modification of local conditions. This then would reflect the idiosyncratic capacities of independent species to disperse, establish themselves, and survive at a local site with a particular combination of environmental conditions. This is becoming the more prominent theory of succession.

Preemptive Competition

Occurs when a competitor recruits to and dominates a habitat, monopolizing all available space, precluding the establishment of potential competitors. This is common in plants. If one plant occupies a position in the landscape, it cannot be filled by another plant.

Interference Competition

Occurs when competitors physically deprive other organism's access to resources. This is a more direct form of competition that involves some form of interference in which aggressive dominance or active inhibition is used to physically deprive other individuals. This is commonly referred to as territoriality.

Barnacles and Niche

One of the earliest studies examining the ecological niche was done by Joe Connell working with barnacles on the Scottish coast. They studies two species of barnacle that were commonly found. Both species settle randomly throughout the intertidal zone, but one species was always found higher in the intertidal zone than the other. Two experiments were performed: 1) They moved rocks bearing Chthalamus from the upper to the lower intertidal zone to see whether the species could survive in the low intertidal zone. 2) Removed Balanus from rocks in the low intertidal and Chthalamus from rocks in the high intertidal. These experiments were designed to show whether each could grow in the other tidal zone if its competitor were absent. Data showed that Chthamalus has a fundamental niche reaching the lower edge of the intertidal zone, but competition with the Balanus and predation, limited the realized niche to only a very small portion toward the top edge of the fundamental range. The Balanus' fundamental and realized niche was exactly the same. Though it has a smaller fundamental niche since it was unable to inhabit the upper intertidal zone, it is able to out compete the Chthamalus to occupy the lower lower part of the intertidal zone.

Cosmopolitan Species

Ones that are distributed over all continents and over a wide range of latitudes, elevations, climates and habitats. These species are much more limited in distribution than they appear at first glance. They are restricted by the fact that the earth is cover by 75% water and they are usually only rare visitors to larges expanses of the terrestrial realm with extremely harsh environments.

Pelagic

Open water organisms

Benthic

Organisms associated with a substrate

Autotrophs

Organisms that can create biomass from inorganic compounds

Heteroptrophs

Organisms that create biomass from organic compounds

Liebig's Law of the Mininmum

Originally developed for agriculture since yield is proportional to the amount of the most limiting nutrient. Population is limited by the single most limiting factor. This is an oversimplification since there is interactions among multiple factors so it's impossible to say what is the "most limiting".

Pagility

Passive dispersal. Dispersing under some other power such as wind or water.

Xerophytes

Plants that are adapted to sunny, dry soil environments thanks to specialized mechanisms that keep stomates open despite low levels of water in their leaves, allowing them to maintain evaporative cooling

Mesophytes

Plants that are adapted to wetter and shadier environments typically close their stomates when subjected to drought and temperature stress.

Sciophytes

Plants that grow best in complete shade

Heliophytes

Plants that grow best in full sunlight

Dispersal as an Ecological Process

Plays an adaptive role in the life history of an organism. The fitness of the organism is increased in some way through the movement away from it's birthplace. This can backfire however, if they land in a less suitable environment (spatial autocorrelation)

Shelford's Law of Tolerance

Range of resources and conditions to which an organism is adapted determines success.

Community Structure

Refers to the static properties that include diversity, composition, and biomass of species

Seasonal Variability Hypothesis

Seasonal variability selects for greater climatic tolerances and therefore wider latitudinal ranges.

Individualistic View of Community (Gleasonian)

Sees community as the mere coexistence of relatively independent individuals and species in the same place at the same time. Focusing primarily on plants, researchers pointed out that occurrence in an area depend primarily on a capacity to immigrate to and grow within a local environment

Eutrophic Lakes

Shallow, highly productive lakes. Light penetrates almost to the bottom with often warmer, low oxygen content water making them subject to algal blooms. Lake turns over each spring and fall, returning nutrients to the surface and oxygen to the depths.

Outline Map

Show a range as an area, which are usually hand drawn, and typically shaded within a boundary. The boundary line defines the limits of the species based on known location data. This sort of map is useful if you just wanted to know the general region in the world that a certain species occurs. Often, much guesswork is involved. The author will use their knowledge of an organism to make educated guesses about the probable distributional limits when adequate data are not available.In general, real distribution is over-estimated and high generalized, as gaps are ignored.

Jump Dispersal

Simply the colonization of a new area over a long distance. Has a selective component where certain organisms are more likely to be successful dispersers (winged).

Carrying Capacity and Body Size

Since carrying capacity of an area is lower for successively higher trophic levels, predictions can be made about their ecological roles and geographic distributions. - Carnivores tend to be larger and more generalized than herbivores - Carnivores typically have to be large enough to overpower their prey - Carnivores tend to be generalists in their prey selection - Carnivores tend to have relatively broad habitat requirements and geographic distributions Ex. Mountain lion is historically the most widely distributed of any New World mammal. It ranges from the Atlantic to the Pacific on both continents and from Alaska to the S tip of Argentina. Herbivores of comparable size tend to have more restricted ranges

Body Size and Environmental Interaction

Since small organisms use fewer resources per individual than larger ones, they can use smaller areas and specialize on more specific resources, yet maintain population densities high enough to avoid extinction. Small organisms are therefore better able to respond to the patchiness of an environment that is most pronounced on a local scale. This also means that small organisms have been able to divide the environment more finely so any geographic area contains a greater number of small bodied species than large ones.

Temporal Environmental Fluctuation

Some places may be inhabited only intermittently as environmental conditions fluctuate or stochastic events affect their size.

Plague Variation

Some species populations exhibit substantial variation over time, most of it reflecting temporal variation in niche parameters. When conditions are good, they undergo population explosions and spread across continents into sink habitats. These favorable weather and food supplies allow range expansion to 1000x the size of the outbreak area from which they originated.

Slope Aspect as a Physical Limiting Factor

Sometimes abrupt transitions between nothern and souther exposures suggests an important role for all of these factors (sunlight, moisture, temperature, etc.) In the northern hemisphere, it's generally cooler and wetter on the northern facing slopes, and warmer and drier on southern facing slopes. This drastically impacts the biotas on either side.

Commensalism

Special form of mutualism where one species benefits and the other is unaffected. Ex. Barnacles on whales

Historical Ecological Communities

Species occur together in associations known as ecological communities. The nature of these association was the subject of debate throughout the 20th century and remains ongoing. Many of the earliest community ecologist studied plant associations

Ecoregions

Specific kinds of animals and microorganisms are associated with specific vegetation formations Ex. Broad band of coniferous forest (boreal life zone) extends around the world at high latitudes in the N hemisphere

Lentic Habitats

Standing water habitats like lakes and ponds. 1) Littoral zone of shallow water where light penetrates to the bottom and rooted aquatic vegetation may be present 2) Limmentic zone is equivalent to the photic zone 3) Profundal zone equivalent to the aphotic zone

Temperate Grassland

Substantial variation in temperature and rainfall annually due to isolation from the ocean. Rainfalls during the summer mostly. Winter temperature are extreme. Drought, fire, and heavy grazing pressures combine to prevent the establishment of woody plants, while favoring the dominance of herbaceous species and grasses. Perennial grasses have growth tissue in the soil and can withstand being eaten. Grasses account for 90% of the biomass but 25% of the plant species in the ecosystem due to the extensive root systems the grasses have below.

Secondary Succession

Succession in a location that has the number of species reduced in the population. Happens after a disturbance and only occurs if the soil and seedbank remain to grow the new assemblage.

Clementsian Succession

Succession is deterministic, predictable and convergent based on climate and soil type. Pioneering species colonize a site and then modify to the where another, better adapted set of species can invade, outcompete, and replace the first. This process is then repeated through a progressive sequence of communities until a relatively stable climax community is established.

Great Salt Lake Species

Supports no fish species and only two macroscopic invertebrates: the brine shrimp and the larvae of the brine fly. Many fish and other invertebrates are found in the freshwater streams that empty into the lake but cannot tolerate the high salinity of the lake itself.

Exploitative Competition

The differential ability of competitors to harvest a limiting resource, which limits the supply that other organisms need to survive. In other words, one species makes resources unavailable to the other by using them up or monopolizing them

Timberline

The distributions of many tree species end at timberline. Across the worlds mountainous regions many investigators have attempted to determine the cause of timberline. The large-scale geographic position of timberline seems to be related to the mean or maximum temperatures during the months of the growing season, which varies with latitude and elevation. It is also influenced locally by other factors such as wind and snow depth. In general timberline increases in elevation with decreasing latitude, reflecting the influence of increasing temperature at lower latitudes.

Local Scale Disturbance

The effect of removing dominant plants or sessile animals allows fast growing, competitively inferior species colonization. The creation of micro-successional stages support many additional species. Ex. Prairie Dogs. Grazing by Prairie Dogs maintains a dynamic mosaic of shortgrass prairie plants. These patches of bare soil provide excellent sites for annual forbs to become established. These forbs are higher in protein and nitrogen and are favored for grazing by bison, elk and pronghorn. Their burrowing can be beneficial to the soil through mixing soil types and organic matter, enhancing soil formation. Their burrows also increase soil aeration and decrease compaction, along with microhabitats and refuge for other animals.

Biosphere

The entire Earth's ecosystem, which is the only completely independent ecosystem.

Niche Partitioning Among Warblers

The five species behave in such a way as to be exposed to different kinds of food. They have different nesting times and thus the times of their peak food requirements are not the same. They are partitioning a limiting resource (insect supply) and therefore occupy different niches.

Eltonian Niche

The function or position of an organism or population within an ecological community. The niche is the role a species plays in a community in terms of its position within a food-web, rather than it's habitat. Emphasizes the functional attributes of animals and their corresponding trophic position.

Diffusion

The gradual spread of individuals or populations outward from the margins of a species range.

Primary Producers

The lowest trophic level of the food chain which produce biomass from inorganic compounds. In other words: plants. Plants are the only autotrophs

Dispersal

The movement of organisms away from their birthplace. Dispersal is not migration, which is a regular seasonal movement.

Pathogenic Disturbance

The outbreak of pathogens, especially plant destroying insects, is an important form of disturbance. Spruce budworms are responsible for nearly as much timber destruction in Canada as fire. It can effect huge stands at a time and the dry, dead foliage will then promote ignition and spread of fires. Sea urchin disease in Jamaica also cause a huge disturbance thanks to the overgrowth of seaweed, which killed nearly 90% of the coral in the reef.

Range Mapping Challenges

The overall complexity and abundance of species, coupled with defining a precise range boundary is difficult

Grinnellian Niche

The particular area within a habitat occupied by an organism. The niche of a species is determined by the habitat in which it lives. The niche is the sum of the habitat requirements that allow a species to persist and produce offspring. Grinnellian approach is to observe as many states of the species in nature as possible and infer the relative effects of possible mechanisms that may constrain its distribution.

Pollen Record Community Change

The pollen record shows that communities change over time, species migrate independently of each other, and they form new and different associations.

Ecological Succession

The progressive change in community and structure and function over ecological time. In short, one assemblage is replace over time by another assemblage.

Basal Metabolic Rate

The rate of energy expenditure of animals at rest. This varies with body mass at around a .75 slope across taxonomic groups on a log scale.

Clumped or Aggregated Distribution Pattern

The real distribution pattern of most individuals tends to be heterogenous with some location having high densities and other much lower. This spatial variation in abundance presumable reflects the extent to which the local environment meets the niche requirements of a species. Each species tends to be most abundant where all niche parameters are in the favorable range.

Coenocline

The study of spatial patters of diversity relative to the environmental or geographic gradient.

Food Chains

The unidirectional paths of energy that flow between species and through communities. Different links in the food chain are called trophic levels, the first of which is green plants, or primary producers

Rainforest Soil Paradox

The worlds richest systems grows on some of the world's poorest soils. High temps and humidity creates incredibly fast decomposition of organic matter therefore little litter accumulates in the soil. Rainforest plants are therefore adapted to conserve nutrient. They often have mutualistic relationship with fungi associated with their roots.

Distribution of Communities in Space and Time

There are five different hypotheses about the spatial patterns of diversity. 1) Communities replace each other abruptly (Clementsian) 2) A few species abruptly replace on another, but most are not associated in discrete communities 3) Same as hypothesis 1), but it is a gradual transition from one community to another 4) Individual species are independent and species replacement along the gradient is random 5) Ranges of most species are nested within the ranges of a few dominant species, but otherwise occur independently of one another. (Ordered distribution at larger scales, but random at local scales)

Saguaro Cactus Distribution

There is a well defined cold temperature limit for these cacti where meteorologic stations have never recorded a 36 hour period without a thaw. One of the best examples of temperature as a physical limiting factor.

Pupfish

They are both euryhaline and eurythermal and occur in rigorous physical environments, including shallow streams and desert marshes.

Flooding

This impacts low-lying areas near rivers and shoreline ecosystems. High water can drown animals and kill plants by restricting oxygen uptake through the roots, therefore inhibiting photosynthesis, starving the vegetation to death. It can also bury many species in the large amounts of sediments that are deposited on the flood plain, killing plants. Regular flooding can be beneficial to increase soil moisture and allow forest growth in regions that are normally too dry to support trees.

Total Productivity

This is a function of solar energy. Everything else being equal, the higher the fixation rate of sunlight into organic material, the more usable energy should be available to be subdivided among individual species and trophic levels. In general, the predicted relationship between productivity and diversity is observed. Widespread, productive habitats such as tropical rainforest and coral reefs are renowned for their great diversity of specialized species and high levels of biodiversity. In contrast, small areas and widespread unproductive habitats like boreal forest and tundra contain fewer and for the most part more generalized species (lower biotic diversity)

Allelopathy

This is a kind of chemical interference competition in which an organism releases a chemical that has a deleterious effect on nearby organisms.

Treefall Gaps

This is another local scale disturbance where the falling of one large tree or limb of a tree can create a sunny microclimate on the forrest floor, which is essential for the establishment of seedlings of some canopy trees.

Time as a Distribution Factor

This is often and overlooked dimension that influences geographic distributions. Even for species long established in areas of suitable and continuous habitat, unless they are powerful dispersers, their realized ranges will usually fall far short of their fundamental ranges. Ex. some trees and other plant species that colonized landscapes in temperate regions following the retreat of the glaciers, 10k years ago are still expanding their ranges toward their fundamental distance, but are centuries behind where they could be. Geographic ranges should be viewed as complex and ever changing, rather than as a static character of any species.

Arctic Tundra

Treeless biome with an open landscape of mosses, lichens, and low shrubs. Characterized by stressful environmental conditions. Really slow decomposition rates create very nutrientless soil. Surface soils are underlain by permafrost and thaw in the summer. Primary productivity, biomass, and diversity are lower than almost all other terrestrial biomes. Cold and dry. Freezing temps for at least 7 moths of the year. Low precipitation than most deserts.

Community Organization Energetic Considerations

Two characteristics of species that strongly influence their effects on community organization are their body size and trophic status. Simply, the larger an organism is, the more energy it requires for maintenance, growth, and reproduction.

Competitive Exclusion

Two species with essentially the same niche cannot coexist because one will always out-compete and displace the other.

Tropical Dry Forests

Typically found in hot lowlands outside the equatorial zone. The climate is way more seasonal than rainforests. 6-7 month dry season and 6-7 month wet season. More nutrient rich soil but it is highly vulnerable to erosion due to heavy rain season. Plant and animal life is tightly linked to the cycle of dry and wet seasons. Trees in wetter regions may be evergreen, while those in dry regions may lose their leaves. Many animal species are shared with the rain forest, including monkeys, parrots, and jaguars. Many of these animals migrate to wetter habitats during the dry season.

Sink Habitats

Unfavorable conditions that constantly drain individuals but immigration maintains the local population

BAM Framework

Uses Biotic, Abiotic, and Movement information to describe niche. The movement information is unique to this framework since Soberon and Peterson noticed dispersal limitations like mountains, rivers, and ocean acting as barriers to realizing their full fundamental niche.

Vicariance

When a species is subdivided by some event in Earth history. Events such as plate tectonics, mountain building, climate changes, and sea level change.

Metapopulation

When a species is subdivided into subpopulations that are linked together over space and time by infrequent, but important dispersal. This is due to patchily distributed species that include isolated populations separated by less habitable areas. Subpopulation are expected to go extinct intermittently, especially if they are sink population. Source-sink dynamics are especially likely to occur on the periphery of a species range, contributing to dynamic shits in range boundaries.

Obligate Mutualism

When one organism cannot survive without the other. In many cases this means that they necessarily share the exact same species distribution. This means they play a major role in controlling distributions.

Amensalism

When one species is unaffected and the other is harmed

Predator Mediated Coexistence

When predators promote the coexistence of otherwise incompatible competitors by preying most heavily on the most abundant species, thus preventing it from driving the competitively inferior species to extinction. Predation can often have the effect of removing dominant species and allowing less dominant species to coexist, which create a mosaic of sub-habitats that supports greater diversity than otherwise possible. Ex. Starfish eat competitively dominant mussels that creates gaps in otherwise continuous mussel beds, which can then be colonized by rapidly growing algae and invertebrates.

Biotic Interactions

When species distributions are limited by other species. There are three kinds of interspecific interactions: -Competition -Predation -Mutualism

Asymmetric Competition

When there is incomplete niche overlap, there is competitive exclusion. There is a reduced niche size in one competitor but not the other when there is a fundamentally stronger competitor.

Clumpy Gappy Distribution

When we see groups of organisms forming across a landscape with certain density gaps between groups depending on environmental variation.

Scale Dependent Abstractions

Whether an individual will be found in a particular grid cell depends on the size of that cell, IE the larger the cell is the high probability that cell will contain at least on individual. Range edges are also scale-dependent, because the exact distributional boundary will depend on the scale at which we connect the locations of individuals to draw an edge.

Freshwater Community Classification

Widely distributed as small isolated lakes, ponds, and marshes. Sometimes connected by long branching streams and rivers.

Wind Disturbance

Wind is the second most frequent and widespread agent of disturbance. It is more important in changing temperate deciduous forests and tropical forests. High winds from tornados strip trees and topple them, creating large zones of downed trees. In the tropics, hurricane winds are even more devastating. This can be beneficial by clearing canopy trees, which increases sunlight in lower vegetation layers, facilitating germination and growth of seedlings that otherwise wouldn't have been able to.

Artificial Fire Suppression

Within the last 200 years this has contributed to the expansion of forest and shrubland at the expense of prairie and other grassland habitats.

Ecotones

Zones of transition between two habitats or communities. Common for ecotones to support a higher number of species than either parent community because it is a region of biotic overlap and has elements of both parental communities co-occurring. Ecotone richness depends on the similarity of the communities involved. -Narrow ecotones can occur with abrupt environmental change and therefore species are likely limited to one community -Wide ecotones often occur with gradual transitions between more similar communities and therefore may support species from both communities and ecotone specialists, creating high species richness.