Bio 1B Berkeley Ecology Terms

What is Ecology?

"oikos" latin for home. Coined by Haekel in the mid 1800s, it is the study of how organisms and the environment in which they live interact and affect each other

Biotic vs. Abiotic Factors

Biotic factors are living components of an ecosystem such as other living organisms, living food

Abiotic factors are non-living components of an ecosystem affecting an organism such as temperature, light, moisture, air currents etc.

Ecological Organization

Earth is a system of interacting parts. Physical Geography and Biogeography can be used to understand these interactions

Organism < Population < Community < Ecosystem < Biosphere

Weather

- The conditions of precipitation and temperature at a given time

- Interaction of amount of solar radiation and air causes air circulation patterns and thus regional weather patterns

Climate

- the weather in some location averaged over some long period of time

- depends on the tilt of the Earth, which is retained throughout the Earth's rotation

- Seasons (annual variations in weather) exist in the Northern and Southern Latitudes and hinges on which latitude is receiving more direct solar radiation

- Climate diagrams can be used to get a good idea of seasonal weather patterns

Solar Radiation

- Energy from the sun

- Solar Radiation exposure is inversely proportional to the number of layers of atmosphere the radiation has to penetrate.

- Due to the angle of the solar radiation path in relation to the Earth's tilt, the poles always get the least solar radiation

Adiabatic Cooling

The cooling effect of reduced pressure on air as it rises higher in the atmosphere and expands. This is one of the chief reasons behind rain in the tropics

Hadley Cells

- Circulation cells exist at the equator,warm air rises and cools dropping rains at equator, cooled air is pushed polewards, dense, dry air descends warms and absorbs moisture

- Sets up alternating layers of wet and dry zones on Earth

IE: Causes San Francisco to have a Mediterranean climate

Prevailing Winds

- Winds that blow in the same direction over large areas of Earth

- These winds decrease in speed around the equator, it has to cover a larger surface of the earth thus air at the equator is lagging

- Prevailing winds contrarily increase in speed around the poles because there is less land to cover

EFFECT: they help create the global ocean currents via frictional drag, and play a role in bottleneck effects and colonization of islands

Climate Diagram

- A standardized form of representing average patterns of variation in temperature and precipitation that identifies several ecologically important climatic factors such as relatively moist periods and periods of drought

- Recognizes that ecological processes are jointly influenced by temperature and moisture

Rain Shadow

the low-rainfall region that exists on the leeward (downwind) side of a mountain range. This rain shadow is the result of the mountain range's causing precipitation on the windward side.

Case Study of the Pacific

Knowing how air circulation and wind patterns allow biologists to hypothesize on how different organisms come to occupy the remote Pacific Islands

- Insects/Spiders brought by storms

- Birds came mainly from North America

Biome Precipitation/Temperature Graph

SEE GRAPH ONLINE

Biome Concept

Coined by Von Humboldt, it is the idea that there are similar types of biological communities all around the world. Main Biotic factors that cause these similarities include annual precipitation and average temperature

Convergent Evolution

process by which unrelated organisms independently evolve similarities when adapting to similar environments

Tropical Rainforest

- Do no experience real seasons

- High average temperature and large amounts of precipitation

- Lots of trees and diverse/complex ecosystems, mass productivity of flora from the moist climate (species 5-30 million)

Grasslands

Only grass and shrubs, no trees due to the unpredictability of rain. Wildfires are common. Plants have long, extended root systems. Animals include bison, large cats, grazing animals like zebra, and rodents like prairie dogs.

Aquatic/Marine Environments

Factors which determine where animals in aquatic biomes live include fresh/salt water, light intensity, flow/wave action

Freshwater regions:

- Littoral

- Limnetic

- Photic

- Aphotic

- Benthic

Ocean:

- Photic

- Aphotic

- Abyssal

- Benthic

- Intertidal

- Pelagic

Littoral Zone

Shore of a fresh water coastal region

Intertidal Zone

Portion of the ocean shoreline that lies between the high and low tide lines

Limnetic Zone

Open water of a fresh water body such as a lake, no rooted plants but light penetrates

Pelagic Zone

The area of the ocean past the continental shelf, with areas of open water often reaching to very great depths

Photic/Aphotic Zone

Photic - superficial layers of water that receive light from sun

Aphotic - deep layers of water that do not receive light

Benthic Zone

bottom of an aquatic ecosystem; consists of sand and sediment and supports its own community of organisms

Abyssal Zone

The deepest portion of the ocean floor where light does not penetrate and where temperatures are cold and pressures intense.

Coral Reef

diverse and productive environment named for the coral animals that make up its primary structure

Hydrothermal Vents

Geysers on the seafloor (abyssal), created where tectonic plates move apart, spewing hot and mineral-rich water into cold ocean depths. Temperature withstanding animals/enzymes valuable to medicine are derived from enzymes in these vents

Dispersal

Physical movement of a species from one location to another. Ocean provides a powerful mode of dispersal for many organisms. Ocean currents provide predictions for types of organisms in given areas

Vicariance

Individuals were there before and the land moved (continental drift). Organisms are where they are because they are attached to the environment where they evolved. A species splits into two large geographically isolated populations due to a barrier

Case Studies:

Nothofagus - tree that was sequestered on one continent. But as the land began to move, they separated with the land

assassin spiders - they do not move very much so they do not participate in dispersal. They hand out in spider webs and kill. They are found at points of continental drift possibly due to vicariance.

Continental Drift/Tectonic Movement

- The hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations.

- The chronology of continental drift provides a hypothesis about history of organisms

Wallace's Line

In southeast asia delineating the abrupt difference in flora and fauna found on the Asian mainland to plants and animals more common to Australia

Biotic Exchange

Animals move from one continent to another as the continents colide with one another

Human Activity changes landscapes

Humans have had huge impacts on ecosystems, especially with regards to agriculture. They have also destroyed many ecosystems, reduced species, less heterogeneity, and high chemical outputs

ie. Kahoolawe Island, Hawaii that was used as a testing facility for its weapon prototypes now has little to no terrestrial life on it

Basics of Population Biology

- Individuals can move between habitats or stay in one place

- Populations are distributed in patches on varying scales (islands, fields, puddles, petri dishes etc)

- Population sizes may be determined by sampling and estimation in conjuncture with extrapolation

Human Population

- Recently passed 7 Billion

- Human population growth as exploded exponentially in recent centuries. The population is growing despite the fact that the birth rate is declining

- Humans have longer lifespans (higher k) due to:

better medical access and care

vaccines (1800)

advances in sanitation (mid 1800s)

antibiotics (1945)

green revolution (1950-1980)

- Countries with higher fertility rates tend to have higher mortality rates

- Per Capita growth rate in humans is DECLINING

SEE POPULATION PYRAMID TYPES

expanding vs. stationary vs. contracting

Birth - Death Model

N(t+1) = N(t) + B - D

ΔN/ΔT = rN (1 - N/K)

Births = (per capita birth rate)*current pop

Death = (per capita death rate)*current pop

r = Birth - Death (+Imigration - Emigration)

r > 0 population growing

r < 0 population shrinking

Population density

- A measurement of the number of people per given unit of land

- Must be careful when extrapolating, must have an equal distribution to do so

Population Growth and Malthus Conclusions

- Depends on biotic and abiotic factors of the environment

- There are always a finite amount of resources

- Found that population growth is exponential

IE: mold and cheese

Demography

the scientific study of population characteristics

Tick Life Cycle (WTF?)

2 year cycle

eggs laid -> larvae -> blood meal -> nymph -> dormant until winter -> blood meal -> adult -> finds a mammal host to mate to lay eggs

Cohort

A population group unified by a specific common characteristic, such as age, and subsequently treated as a statistical unit.

Fecundity

The ability to reproduce

Survivorship

It is the proportion of the original cohort surviving at a given time after the defining event (such as birth). Also varies within species due to biogeography, developed vs. non-developed countries, biotic vs. abiotic factors.

Case Study: 1978 Cohort of Cactus Ground Finch

1983 increased rain lead to a spike in fecundity

1985 there was a drought that created zero offspring

Survivorship Curve

A plot of the number of members of a cohort that are still alive at each age; one way to represent age-specific mortality. % survived on Y axis, time on X axis

Three types:

1. High survival early/middle age groups lower survival later on

2. Average survival throughout life

3. Decreasing survival early on carried on through life

Principle of Allocation

The principle that if an organism allocates energy to one function, such as growth or reproduction, it reduces the amount of energy available to other functions, such as defense. Homeostasis must be met before any of the other functions, as stress conditions increase, more is allocated into homeostasis

1. typical conditions, normal resources: homeostasis is met first, remainder is divided amongst other functions

2. typical conditions, abundant resources: there is enough resources energy left over from homeostasis that most other functions can be fully satisfied

3. stressful conditions, normal resources: more is allocated to homeostasis, other functions become more limited

Carrying Capacity (K)

Largest number of individuals of a population that a given environment can support. Population exhibits logistic growth, limited by abiotic or biotic factors (predation, environment size, food supply)

ΔN/ΔT = rN (1 - N/K)

According to equation, as N gets closer to K, the rate at which the population grows shrinks and may even go negative for a period

Life History Strategies

Represent a balance between two conflicting forces, survival and reproduction. R vs. K selection

R-selected Organisms

"Live Fast Die Young"

- Mature rapidly; early age of first reproduction

- Relatively short life span

- Large number of offspring at one time and fewer reproductive events

- High mortality rate and low offspring rate

- Minimal parental care/investment

K-selected Organisms

"Live Long and Prosper"

- Mature more slowly; a later age of first reproduction

- Longer Lifespan

- Few Offspring at a time and more reproductive events spread out over a longer span of time

- Low Mortality rate and a high offspring survival rate

- Have High parental investment

Ie: Humans

Density Independent vs. Dependent Populations

Independent - Limiting factors that affect the population, regardless of the size(abiotic). It is thought to effect the exponential part of the growth curve

Ie. Habitat conditions, weather patterns

Dependent - Referring to any characteristic that varies according to an increase in population density.

Ie. Intra/Interspecific Competition

Biological Dispersal

regular - uniform distribution of the area in question

Ie: bird territories, farming

random - no defined distribution of organisms

Ie: settlement of seeds from a tree/plant

clumped - habitat patches are formed, niches

Ie: habitat patches for the checkerspot butterfly

Metapopulation

A group of spatially separated populations of one species that occasionally interact through immigration and emigration via habitat corridors.

Ex. Big Horn Sheep. These sheep live in patchy habitats and must be able to travel between these niches via habitat corridors to maintain the population in some patches (rescue effect). Human development is cutting off certain habitat corridors thus ecologists and tagging and monitoring these animal species to monitor gene flow

Ex. Humpback whales highlights the usefulness of DNA sampling in plotting out habitat corridors with large distributions

Ex. Swine Flu - DNA sampling used to trace origins

BIDE Model

The change of density of the population via immigration and emigration

-birth and immigration increase density

-death and emigration decrease density

B+I-D-E

Habitat Corridor

A strip of land that aids in the movement of species between disconnected areas of their natural habitat.

Rescue Effect

Small populations can be maintained in smaller areas, as long as the population can be rescued by immigration from other patches

Conservation Biology/Managing Populations

Application of biology to counter the loss of biodiversity. Can replace/repopulate/recolonize areas by aiding in the physical movement of species

Applications:

- Species Conservation

- Pest management

- Disease biology

Species Competition

With limited resources, both species are harmed and have decreased amount of resources and population size

Parasitism/Herbivory/Predation

One species will prosper and survive, the other will be killed off or reduced in number

Mutualism/Symbiosis

Relationship in which both species benefit. Whale sharks and remora

Commensalism

An interaction in which one species benefits while the other is unaffected

Amensalism

An interaction in which one species is harmed while the other is unaffected

Interspecific Competition

In a community competition for resources between members of different species. Causes a negative impact on both species. If the two species compete for the same resources, one will succeed more than the other and one will invariably go to extinction

Ie: Gause and Paramecium

or Intertidal Barnacles in which the rock barnacles that live deeper underwater are a better competitor, but cannot withstand desiccation from the air, stellate barnacles on the other hand persist better near surface because they can stand the desiccation

Intraspecific Competition

Community competition for resources among members of the same species. This goes in conjunction with the idea of carrying capacity, and Malthus's theories of limited resources

Competitive Exclusion Principle

States that two species competing for the same, limiting resources cannot coexist in the same niche indefinitely. One species will always use the resources

more efficiently and cause the other species to become extinct locally.

Realized vs. Fundamental Niche

Realized niche is where an organism lives with the presence of competition and fundamental niche is what it could be without competition (thus much broader)

Modeling Interactions (with predation)

ΔN/ΔT = (r(max) - r(N/K))N

r(max) is maximum growth rate

r(N/K) is the effect of density on the growth rate

Predator-Prey competition:

r(prey) = r(a,max) - f(Na) - f(Nb)

r(predator) = r(b,max) - f(Nb) + f(Na)

Two eventual outcomes: equilibrium or extinction

Lotka-Volterra Equation (predator-prey cycles)

looks at the affect of one species on the rate of growth of another. Cyclical relationship between prey and predator: high points of abundance for prey population marks low points for predator and vice versa. This is because as the prey becomes rare, the remaining prey can escape predators more easily and reproduce. As a result, predators start dying off from starvation.

Rarity Advantage

- With a rare trait, a species can occupy a unique niche and have a survival advantage over more redundant species.

- Coexistence enables a species to grow better when it is rare and its competitor is abundant, which helps it to avoid extinction.

Stable Coexistence

Two species can coexist perpetually if each species is more affected by its own intraspecific interactions than the interspecific interactions with the other species.

Resource Partitioning

Biological community in which various populations share environmental resources through specialization thereby reducing direct competition

Ie. Different sized lizards that inhabit different parts of the tree so that they dont outcompete other lizards

Ie. Coexistence of Paramecium, as when two species are grown together, species split up to feed on different regions of the medium

Character Displacement

The tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species. Some characteristics may change to allow exploitation of slightly different resources and reduce competition between species

Ie. Birds and the bees

Facilitation

An interaction between two species in which at least one organism benefits and the other either benefits or is unaffected.

Ie. Fig wasp eating and pollinating the fig vs. not

Remora eating leftover food from shark

Invasion Biology

Invasive species: A species expanding past its geographical range, usually causing negative ecological, environmental of health effects

Reasons: Ecological Release, Facilitation in the new environment, and increased dispersal

Ecological Release

Removal of a negative selection pressure (competitor) by placing the organism in a non-native environment will encourage search for new niches and enhance survival

Ex. Humans expanding via boat, plane etc.

Propagule Pressure

The frequency that invasive species show up in a new area (determines the likelihood of invasion happening) this is coupled with dispersal ability and ecological release

Ex. Argentine Ant and super colonies

Species Composition

The species that occur in a given community

Community Assembly

The creation of an ecological community through a sequence of invasions of species

Transect

A sampling technique whereby various species are present at regular intervals along a line crossing the area of study

Edge Effect

the condition in which, at ecosystem boundaries, there is greater species diversity and biological density than there is in the heart of ecological communities. Edge effects are especially pronounced in small habitat fragments where they may extend throughout the patch. Conditions that effect the edges translate into the middle.

Habitat Structure

Habitat complexity can influence CARRYING CAPACITY ( total number of organisms) and BIODIVERSITY (total number of different kinds of organisms). Example old growth forest versus tree plantations, beach versus coral reef. The idea of conservation has shifted from saving individual organisms to saving habitat.

Species Turnover

-The time a species lasts before it is replaced.

-Changes in species composition resulting from some species becoming extinct and others immigrating

Succession (Primary and Secondary)

Succession - process by which replacement of species in an ecosystem occurs

Primary - nothing was there to begin with, it represents colonization. Early colonists are normally nitrogen fixers like bacteria and lichens

Secondary - primary succession provides foundation and nutrients for new plant species to be introduced and compete with existing plants. Biological communities become more complex

Fire Adapted Chaparrals and their relation to Succession

- They are a good example of secondary ecological succession

- Fires comes in and destroys most of the visible life, then primary succession sets in and the are becomes recolonized

- Advantages to fire: some trees need fire as part of their reproductive cycle. Disturbance of fire also opens new niches

- Humans have disturbed the cycle of burning and regrowth and thus there is a massive fuel load build up that may lead to massive destructive fires

Climax Community

The ecosystem that would thrive in the absence of disturbances and where it will remain for a while

Ecological Transition

(After Succession) Takes place and the community is permanently changed (climate or soil have changed)

Disturbance

Anything that will alter the state of the ecosystem so that ecological transition may occur

Ie. change in climate/soil composition

Decomposition

Decaying caused by bacterial or fungal action

Forensic Biology

Using a decaying organism as a field of study for succession (like an ecosystem). Can find time of death, cause of death via DNA analysis

Trophic Interactions

Movements of energy across animals at different trophic levels

Trophic Levels

The hierarchical levels of the food chain through which energy flows from primary producers to primary consumers, secondary consumers and so on.

Omnivores

Eat consumers and producers that are lower than they are on the food chain

Decomposers

Organisms that break down wastes and dead organisms and return raw materials to the environment

Food Web

Network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem (group of food chains)

Food Chain

The pathway of energy transfer through various stages as a result of the feeding patterns of a series of organisms

Trophic Cascade

The phenomenon of how feeding at one level of the food web affects other levels of the food web.

Ie. wolf eats elk that can no longer eat will willow plant

Keystone Species

A species whose impact on its community or ecosystem are much larger and more influential than would be expected from mere abundance.

Ie. Sea stars, fig trees and otters

Ie. Wolf and elk experiment, when the wolves were removed, elk population increased and in turn the willow population decreased (trophic cascade)

Top-down effect vs. Bottom-up Effect

Top-down effect - predators/higher organisms of food web control ecosystem

Bottom-up effect - lower organisms of food web are the controlling factor of the ecosystem

Gross Primary Productivity

Total amount of (solar/chemical) energy captured by primary producers

Net Primary Productivity

The amount of energy made available to each trophic level beyond the primary producer. Typically only 10% of the energy gets passed on to the next higher trophic level. Thus secondary and tertiary consumers must eat more to obtain the same amount of energy

Trophic Pyramids

- These show the different levels of the food web and the flow of either biomass or energy

- Distributions of these pyramids are different based on habitat: energy related pyramids are always in a pyramid shape, but biomass pyramids have different characteristics when comparing aquatic and terrestrial life: ocean has more biomass at intermediate trophic level, terrestrial biomass follows pyramid shape