Ch13, 36, 37 exam 5 Flashcards
The study of populations
- Populations are studied for the way they change, the way they interact with other populations, and the way they interact with their environments
- In order to understand these interactions scientists must understand the forces that act on populations
POPULATION GROWTH
•ALL POPULATIONS TEND TO INCREASE IN SIZE UNLESS LIMITED BY SOME FACTOR OR FACTORS
GROWTH UNDER THESE CONDITIONS IS CALLED: (population growth)
• EXPONENTIAL
•WHEN THERE IS SOME LIMITING FACTOR THEN POPULATIONS DON’T GROW UNCHECKED AND THERE IS AN EQUILIBRIUM POINT:
•ZERO POPULTAION GROWTH OR THE STATIONARY PHASE
REGULATION OF POPULATION SIZE
•BIOTIC FACTORS : Predation, parasitism, competition : interspecific and intraspecific •ABIOTIC FACTORS : weather •DENSITY-DEPENDENT EFFECTS –Predation –Disease (parasites) –Competition •DENSITY-INDEPENDENT EFFECTS –Usually abiotic : natural disasters –Weather
FACTORS AFFECTING
POPULATION GROWTH
•Density independent: abiotic –Weather –Natural disasters •Density dependent: biotic –Competition •Interspecific : food, shelter •Intraspecific : mating, nesting •Predation •Parasitism
COMMUNITIES
- GROUPS OF POPULATIONS LIVING TOGETHER
- COMPOSITION: NUMBER OF DIFFERENT SPECIES
- DIVERSITY : THE RELATIVE ABUNDANCE OF EACH SPECIES
HABITAT :
–WHERE A SPECIES LIVES (ITS ADDRESS)
•NICHE :
–THE ROLE IT PLAYS IN THE COMMUNITY (ITS JOB)
ECOLOGY
•The study of ecology is in many instances the study of the behavior of groups of living things:
uThe fundamental niche is
the niche of the organism in the absence of competition.
uThe fundamental niche represents
the potential of the organism.
uWith competition, the fundamental niche is not fully realized and the population occupies
its Realized Niche.
uLimiting Factors limit
population growth.
uLimiting Factors may be
resources, or other environmental factors such as temperature or predators.
uLimiting Factors generally are t
hose resources that are scarce relative to their demand.
uWhat is a key limiting factor for most terrestrial (land) organisms?
uWater is a key limiting factor for most terrestrial organisms.
another examples of limiting factors
uPhysical extremes, such as hot or cold temperatures may also serve as limiting factors.
uWhat are limiting factors at the bottom of lakes and the oceans?
sunlight
When does competition occurs
uCompetition occurs between (or among) consumers that share a resource or resources (a resource pool).
uCompetitive exclusion
is the term used when one consumer of a resource pool is so efficient as to exclude other consumers of that resource pool.
The force behind competitive exclusion is
population growth in the face of limited resources
Ecosystem Complexity
- Natural formed ecosystems are very complex
- There are many different organisms all having complex relationships to the other organisms
- When factors change in the ecosystem all of the members are affected.
Evolution is propelled by the following forces:
–Population genetics :changes in genetic make-up of a population
–Natural selection : environmental forces on the gene pool
–Speciation : development of new populations
Fitness:
physical or behavioral characteristics that enable an individual to survive and reproduce.
•Variation :
traits which vary among individuals within a population.
Gene pool :
the total number of alleles available for reproduction within a population.
•Diversity
: the inheritable variations among a population
Adaptation
: characteristic which enables individual to survive and reproduce under specific environmental stresses
Population Genetics
- Studies of the frequencies of a certain allele within a group of individuals (population)
- Predictions about evolution (changes in gene pool) indicated by Hardy-Weinberg Law
Hardy-Weinberg Law
•Describes conditions under which the gene pool will not change : that is no evolution will occur.
–No mutations : no changes in alleles
–Mating is completely random : mating is not based an phenotypes
–No genetic drift : large populations where gene frequencies don’t change
–No gene flow : no alleles leave the population (emigration), no new alleles enter (immigration)
–No natural selection : no environmental forces favor one genotype over another
Natural selection
•Environmental forces upon the gene frequency within a population
FORCES of EVOLUTION
- Mutations
- Non-random mating
- Genetic drift
- Gene flow
- Natural selection
artificial selection
Man has been practicing artificial selection with domestic animals ever since he started domesticating animals
- Natural forces act in the same way over long periods of time on all living creatures.
Natural selection:
Darwin’s Theory of Evolution
Requirements of Natural Selection :
–Variations
–Inheritance
–Differential adaptedness
–Differential reproduction
Types of Natural Selection
–Stabilizing selection
–Directional selection
–Disruptive selection
Speciation
•Isolation
–Premating •Habitat •Temporal •Behavioral •Mechanical –Postmating •Gamete •Zygote •Sterility •Fitness
Speciation
- Allopatric speciation
- Sympatric speciation
- Parapatric speciation
Adaptive radiation
Development of different species in response to different environmental pressures :
Galapagos’ finches
Phyletic gradualism vs. punctuated equilibrium
Phyletic gradualism vs. punctuated equilibrium
- gradual evolution vs stable evolution over long periods of time followed by a punctuated evolutionary growth
SURVIVORSHIP
•The proportion of a population that survives to a particular age can be graphed and used to help define the type of life style that organism follows
There are three basic types of survivors :
Type I , II, III
•Type I :
young have a good chance of surviving
Type II :
the chances of surviving does not change with age
•Type III :
the chances of surviving increases with age
Reproductive Success
uFactors contributing to reproductive success:
sage at first reproduction (maturity)
snumber of offspring produced per reproductive event (fecundity).
snumber of reproductive events (parity)
slevel of parental care
Potential Limiting Factors to
Human Population growth
uFood production uEnergy distribution uWaste disposal uCrowding and Competition sInterspecific competition sIntraspecific competition
succession
uSuccession is the change (development) of a community over time.
uSuccession is a directional, cumulative change in the association of interacting species that occupy a given area, through time.
uSuccession continues through time until
a condition is reached where the interacting populations replace themselves rather than being displaced by other species.
uEach stage generally lasts from 1-500 years.
uSuccession may begin by
colonization of previously barren landscape.
uPrimary Succession begins by
the establishment of organisms on substrate not previously colonized.
uPrimary Succession,
example,
succession begins by organisms growing on exposed rock after a glacier has melted.
uThe initial colonizing organisms in primary succession are called
pioneer organisms.
example of pioneer organism
uLichen is a combination organism featuring a fungi growing together with either an algae or a cyanobacteria.
uThe lichen is a successful system because
- the partners work together.
uThe cyanobacteria or algae produce sugar, while the fungi provides housing and collects water and inorganic nutrients.
lichen system
uAs the lichen grows, it slowly dissolves the rock substrate.
uWind deposits debris around the lichen, and a soil slowly develops.
uThe small quantity of soil is soon colonized by a variety of organisms with further development of this mini-ecosystem.
uWith an increase in structural diversity come an
increase in niche opportunities.
uThe increase in niche opportunities is accompanied by
an increase in species diversity.
Current Concept of Succession
uAs further studies of succession have taken place, it has been shown to be a continuum process, with one community type gradually being replaced by another.
uSecondary succession involves
the disruption of an established community (stage or climax) which resets the sequence to an earlier stage.
uSecondary succession is often the result of
human based disturbances such as… uFARMING uMINING uOr natural disasters : uFloods uFires
What is a Biome ?
•Ecosystems that share similarities in temperature, precipitation and certain other qualities that promote the growth of similar organisms
Biomes are defined by? and why?
As climate has a great influence on stable plant species, these ecosystems are usually defined by their climate and plants
How are biomes formed?
Biomes are distributed across the Earth based primarily on climate. Therefore, in areas that are far apart, you will sometimes find similar plants and animals because the climate is similar.
factors affecting climates
One factor affecting climate is latitude. Typically, the farther you move north or south of the equator, the colder the temperature gets.
Another factor affecting climate is elevation. The higher you go in elevation, the colder the temperature gets.
Biomes usually found at cold latitudes are
far from the equator are sometimes also found on high mountains at low latitudes. Typically, a climb of 100 feet in elevation is equivalent to traveling 600 miles northward
Biomes
terresterials
marine
fresh water
Terrestrial
Tropical rainforest Savannah Desert Chaparral/Steppe Temperate grassland Temperate deciduous forest Taiga (boreal forest) Tundra
Marine
Open ocean
Coral Reef
Estuary
Freshwater
Wetlands (Swamps, marshes, etc.)
Tropical Rainforest
- Typically found near the equator
- Receives more than 200 cm of rain annually
- Temperatures typically fall between 20oC and 25oC for the entire year
- As many as 50% of all the world’s animal species may be found here
Tropical Savanna
- Grasslands with a few scattered trees
- Experience a wet and dry season
- Hot temperatures
- Annual rainfall is between 50 and 127 cm
- More species of grazing mammals than any other biome
Desert
- Typically found between 25o and 40o latitude
- Receives less than 25 cm of rain each year
- Temperatures typically range between 20oC and 25oC but some extreme deserts can reach temperatures higher than 38oC and lower than –15oC
Chaparral
- Found between 32o and 40o latitude on the west coast of continents
- Receives between 35 and 70 cm of rain, usually in the winter
- Extremely resistant to drought and weather events
Grassland
- Because of the dry climate, trees are found only near water sources such as streams
- Usually receives between 50 and 90 cm of rainfall each year
- Summer temperatures can reach up to 38oC, and winter temperatures can fall to –40oC
Temperate Deciduous Forest
- Moderate climate
- Most trees will lose their leaves in the winter
- Temperatures range between –30oC and 30oC
- Averages from 75 to 150 cm of precipitation
- Well developed understory
Temperate Boreal Forest
- Also known as Taiga
- Typically found between 45o and 60o North latitude
- Cold climate with summer rains
- Very few reptiles
- Limited understory
- Snow is primary form of precipitation (40 – 100 cm annually)
Tundra
- Means treeless or marshy plain
- Characterized by permafrost – permanently frozen soil starting as high as a few centimeters below the surface – which severely limits plant growth
- Winter temperatures average –34oC while summer temperatures usually average below 10oC
- Low precipitation (15–25 cm per year) but ground is usually wet because of low evaporation
Open ocean
Far from shore
Low nutrient
Plankton : basis of food chain
Mobile animals
coral reefs
Warm, tropical water Shallow water Built by animals : coral Highly diverse
estuary
Freshwater combines with sea water
Highly diverse
Teams with life
wetlands
Swamps , marshes
Richest of all biomes
Highly diverse
Important in water cycle
