Biocore 381: Ecology

Mechanism for change

component of Darwin's Theory; the force now known as 'selection'

Ecosystem

The biota, atmosphere, hydrosphere, lithosphere, and their interconnections

Climate

temperature, atmospheric circulation (wind), precipitation (water), and light levels and quality

Biomes

the major types of habitats where organisms are found

Microclimate

variations of heat, moisture, light, etc. on a scale of a few kilometers, meters, or centimeters

Evolutionary Adaptation

An accumulation of inherited characteristics that enhance an organisms ability to survive and res

C3 Photosynthetic Pathways

Occurs in early spring/cycle. ex. forbs

C4 Photosynthetic Pathways

Occurs in mid summer, reduces water loss. ex. tall grasses

Prairie

a community dominated by grasses, with less than one mature tree per acre

Ruminants

species that have 4-chambered stomachs that provides extra steps in digesting grasses, allows more efficient use of food and for animals to collect food and move on

Population

a group of organisms of the same species living together in the same place at the same time

Darwin's Theory

As a population creates more offspring than can survive, there is competition for existence, so long as there is variation among individuals, some individuals will have a greater fitness and be able to pass on their traits, leading to the adaptation of a species.

Descent with modification

A component of Darwin's theory that newer organisms are the modified descendants of much older organisms; commonly depicted with a cladogram/tree of life

Natural Selection

The process that eliminates individuals that are less likely to survive in an environment, while allowing other individuals with favorable traits to reproduce and increases in numbers, leading to the evolutionary adaptation of populations to their environment.

Ecology

the study of the relationships among organisms or groups of organisms and between organisms and their environment

Environment

the setting within which an organism can function as a living system and outside of which it is no longer capable of living

Open system

a system that exchanges matter and energy with its surroundings; ex. organisms

Range of Tolerance

the levels of an environmental factor within which an organism can live; can very over a lifetime

Optimum Range

The levels of an environmental factor within which an organism performs best; can very over a lifetime

Ecological Niche

The sum total of a species relationship with the biotic and abiotic resources in its environment

Ramets

independent members of a clone

Population size

the numbers of individuals (ramets) in a population, often expressed as density; a result of inputs (immigrants, births) and outputs (death, emigration)

Density

the number of organisms per unit area or volume

Advantages of being rare are...

harder for predators to locate; organism to organism transmitted diseases are less common

Advantages of being common are...

protection from predators; protection from harsh physical environmental conditions (ex. penguins); ability to specialize (ex. prairie dogs)

Complete Survey

technique to measure population size, count every individual in an area

Sampling techniques

techniques to measure population size by measuring a subset to represent the whole population

Quadrats

sampling technique, count all numbers of individuals in a defined shape and size. Best for stationary organisms.

Mark-Recapture technique

sampling technique used for organisms that move.

Assumptions of Mark-Recapture technique

random capture, no loss of marks, no immigration, emigration, births, or deaths

Photos (sampling technique)

sampling technique that involves taking photos and counting individuals, works best with herds

Transects (sampling technique)

indirect method of sampling technique, that involves counting tracks, nests, pellets, etc.

Population Dispersion

spatial arrangement of a populations, including clumped, uniform, or random

random distribution

distribution in which individuals within a population have an equal chance of living anywhere within an area; result of individuals of a population having neutral interactions

Uniform distribution

distribution in which individuals are uniformly spaced; result of (1) individuals claiming an exclusive patch of land or (2) antagonistic relations between individuals.

clumped distribution

individuals have a higher chance of being found in some areas (together) than in others; results from (1) mutual attraction or (2) clumped resources.

Exponential Growth Model

represents continuous growth in an unlimited environment

Logistic Growth Model

represents the growth of a population in an environment with limited resources; as resources decrease, population growth rate slows and eventually stops

carrying capacity (K)

the population size at which population growth stops; the # of individuals that an environment can support

the intrinsic rate of increase (rmax)

the maximum per capita rate of increase of a population, achieved by a species under ideal environmental conditions

realized/actual rate of increase (r)

the actual per capita rate of increase of a population, found by subtracting the death rate from the birth rate.

Life History

Identifiable steps an organism goes through from birth to death; can be organized by form, activity, etc

Opportunity Cost

the sum of the benefits an organism forfeits by not being able to perform some other activity during the time when it is engaging in a given activity

Life table

an age-specific summary of the survival pattern of a population following the fate of cohorts

Cohorts

individuals of the same population that were born at the same time

Survivorship curve

curve which shows patters of life and death within a population by presenting the survival of a species

Type 1 Survivorship Curve

relatively high rate of survival among young and middle-aged individuals followed by a high death rate among aged individuals

Type 2 Survivorship Curve

constant rates of survival throughout life, producing a straight line pattern

Type 3 Survivorship Curve

high mortality rates among the young are followed by relatively high rates of survivorship

Minimum Viable Population (MVP)

The smallest number of individuals needed to perpetuate a population; the smallest population can be before the 'extinction vortex' begins

Extinction Vortex

small population --> inbreeding & random genetic drift --> Loss of genetic variability --> Reduction in individual fitness and population adaptability --> lower reproduction & higher mortality --> smaller population

Metapopulation

a group of more or less isolated subpopulations of the same species

Source population

a population in which births exceed deaths, often producing more individuals than can be accommodated by available resources

Sink population

population in which deaths exceed births or in which no reproduction occurs

Community

A group of species living together in the same place at the same time

Diversity

a measure of species abundance within a community

Species richness

Component of Diversity; number of species per unit area or volume, analogous to density

Species Equitability/Evenness

Component of Diversity; the relative abundance of species, comparing the proportions of each species within an area

Shannon Index (aka Diversity Index)

Used to determine the diversity of species within a community, taking into account both species richness and species evenness; the greater the index, the more diverse the community

Factors that bring species together to form a community

(1) similar abiotic environmental requirements; overlapping ranges of tolerance, (2) dispersal to the site, (3) Interactions between different species that cause the community to function as a unit

Competition

interactions that occur when two organisms or populations use the same limited resource; interactions that have a negative impact on both organisms

guild

a set of species that are potential competitors because they exploit the same resources

intraspecific competition

competition between members of the same species

interspecific competition

competition between individuals of two species

Lotka-Volterra Model

models the competition between two species, predicts that two competitors can coexist, both with stable populations, when intraspecific competition is stronger than interspecific competition

Competitive Exclusion Principle

if two species are competing for the same limited resource, one of the species will be able to use the resource more efficiently than the other, and the former will eliminate the latter; two species with identical niches cannot coexist indefinitely -- ex. grey and red squirrel

Fundamental Niche

the environmental conditions within which a species might live in the absence of interaction with other species

Realized Niche

the actual environmental conditions within which a species lives, because of restrictions imposed by interactions with other species

Character displacement

the tendency for characteristics to be more divergent in two sympatric populations than in two allopatric populations; species that compete for the same resources, over time are selected to have different traits to reduces competitive pressures

sympatric

occurring in the same geographic area

allopatric

occurring in separate geographic areas

Resource Partitioning

potential competitors occupy/exploit different parts of their potential habitat -- this is a long-term outcome of competitive pressures

Exploitive Interactions

interactions between species that enhance the fitness of one individual at the expense of another; one organism benefits while the other species does not -- ex. parasites (ticks), chestnut blight

Mutualism

Interactions between organisms in which both organisms benefit - ex. mycorrhizal fungus, coral and zooxanthellae, nemo and anemone, zebra and birds

Mycorrhizae

mutualistic relationship between plant roots and fungi in which the fungus received energy from excretions and plants get access to inorganic nutrients and water

foundation species (aka dominant species)

species that have substantial influences on the community structure, as a result of their high biomass - ex. coral,

Theory of Island Biogeography

a theory to predict the number of species that an island can hold, based on the impact of island size and distance from the mainland on immigration and extinction rates; predicts that large/near islands will have more species than far/small islands

ecological succession

a shift in species composition and community structure over time

primary succession

ecological succession in a location that has never supported a biotic community - ex. Mount St. Helen, Glacier Bay Alaska

secondary succession

ecological succession in a location where an existing biological community has been disrupted by a disturbance

pioneer community

opportunists; r-selected; the first set of species to arrive after a disturbance has past or a previously uninhabited habitat is created

climax community

survivalists; K-selected; set of species that follows the pioneer community, this community remains relatively stable until another disturbance

Contemporary model of succession

patters of community change occur differently at every site and are strongly influenced by the species that comprise it and the initial conditions of the site and its surroundings

Facilitation (model)

early colonists modify the environment, making it less suitable for themselves and more suitable others

Inhibition (model)

early colonists occupy the site and prevent other species from colonizing, and persist until disturbed; in this model, the pioneer community is the climax community

Tolerance (model)

early colonists modify the environment so that it becomes less suitable for themselves, and neither more nor less suitable for later colonists

Keystone species

non-abundant species whose presence helps maintain community structure, diversity and complexity, without which, the community may collapse -- ex. beavers

Species Conservation Plans

multi-step process to prevent the extinction of species; includes a current review, info on biology and habitat requirements, population viability analysis, threat analysis, and value of species

population viability analysis (PVA)

the process that determines the probability that a population will go extinct within a given number of years.

Longitudinal Study (of Succession)

Same location studied across a long period of time

Comparative Study (of Succession)

Study that compares different but similar locations around the same time

Prairie Grass Adaptations

(1) roots can be up to 6 feet deep (2) narrow leaves expose (less wind resistance and prevents overheating) (3) many vertical leaves (4) leaves and stems contain silica (structural support deter insect grazers) (5) tips of leaves are at an angle (reduces light exposure) (6) wind pollinated (7) growing points are at the base of the plant

Prairie Forb Adaptations

(1) small leaves (2) hairy leaves and stem (reduce heat) (3)thick leaves (reduce water loss) (4) chemicals in tissues, hairs and spines (reduce grazing pressures)

Major Abiotic Selection Pressures for Prairie Animals

hot summer, cold winters, frequent drought, strong winds, fore, seasonally changing spatial structure of the outdoor room

landscape

composed of multiple interconnected communities; can be made up of patches and corridors.

corridors

passageway linking patches in a matrix, can increase species diversity and migration, and the loss of which can result in a decrease in population size and species diversity

Patches

a small area, distinct in form and composition from the surroundings, the arrangement of patches create the landscape structure, composed of an edge and interior

edge (aka ectone)

an area of environmental transition; the habitat and

nitrogen fixation

Process of converting nitrogen gas into ammonia

Nitrification

ammonia is converted to nitrate ions (NO3-).