List the 5 levels of complexity
individuals, populations, communities, ecosystems, and the biosphere
The simplest level is
the individual- a single organism
Natural selection operates at the level of
the individual because it is the individual that must survive and reproduce
The second level of complexity is
Population
A Population is
the individuals that belong to the same species and live in a given area at a particular time
Where does Evolution occur?
Evolution occurs at the level of the population
what is the third level of complexity?
is the community
A community is
all of the populations of organisms within a given area
Scientists who study communities are interested in
how species interact with one another
An ecosystem consists
of all the abiotic and biotic components in a particular location
What do ecosystem ecologists study?
study flows of energy and matter, such as cycling of nutrients through the system
The largest and most complex system environmental scientists study is the
biosphere, which incorporates all of the Earth's ecosystems
Population Size (N):
The total number of individuals within a defined area at a given time
Population Density
The number of individuals per unit of area at a given time
Knowing a Population's density, in addition to its size, can help scientists estimate whether a species
is rare or abundant
Scientists also study population density to determine
whether a population in a particular location is so dense that it might outstrip its food supply
Age structure
A description of how many individuals fit into a particular age categories in a population
Knowing a population's age structure
helps ecologists predict how rapidly a population can grow
Limiting Resource
A resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size
Density dependent factors
A factor that influences an individual's probability of survival and reproduction in a manner that depends on the size of the population Ex: parasites, limiting food
Examples of Density dependent factors
water, food, nest sites
Density Independent Factor
A factor that has the same effect on an individual's probability of survival and the amount of reproduction at any population size. (population size doesn't matter)
Examples of Density Independent Factors
tornados, fires, floods, hurricanes
Carrying Capacity (K)
The limit of how many individuals in a population the environment can sustain
Population growth models
Mathematical equations that can be used to predict population size at any moment in time
Population Growth rate
the number of offspring an individual can produce in a given time period, minus the deaths
Intrinsic Growth rate (r)
The maximum potential for growth of a population under ideal conditions with unlimited resources
Exponential growth model
A growth model that estimates a population's future size after a period of time, based on the intrinsic growth rate, and the number of reproducing individuals in the population
J-shaped Curve
The curve of an exponential growth model when graphed
Logistic Growth model
A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment.
What type of curve does the logistic growth model produce?
An S-shaped curve
Overshoot
When a population becomes larger than the environment's carrying capacity
Die-off
A rapid decline in a population due to death
K-selected Species
A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity
Descriptions of K-selected Species
long life span, long time to reproductive maturity, few reproductive events, few offspring, large offspring, present parental care, population growth rate is slow, and is regulated by density dependent, and is always stable
r-selected species
A species that has a high intrinsic growth rate, which often leads to population overshoots and die offs
Survivorship Curve
A graph that represents the distinct patterns of species survival as a function of age
Type 1 survivorship Curve
A pattern of survival over time in which there is a high survival throughout most of the life span, but then individuals start to die off in large numbers as they approach old age
Type II
A pattern of survival over time in which there is a relatively constant decline in survivorship
Type III
low survivorship early in life with few individuals reaching adulthood
Symbiotic Relationship
the relationship between two species that live in close association with each other
Competition
The struggle of individuals to obtain a shared limiting resource
Competitive Exclusion Principle
the principle stating that two species competing for the same limiting resource cannot coexist
Resource Partitioning
when two species divide a resource based on differences in their behavior or morphology
natural selection
will favor individuals that overlap less with other species in the resource they use
predation
An interaction in which one animal kills and consumes another animal
Parasitism
An interaction in which one organism lives on or in another organism
Pathogen
A parasite that causes disease in its host
Herbivory
Animal consumes a producer
mutualism
An interaction between two species that increases the chances of survival or reproduction for both species
Commensalism
A relationship between species in which one species benefits and the other species is neither harmed nor helped
Keystone Species
A species that plays a far more important role in its community than its relative abundance might suggest
Ecosystem Engineer
A keystone species that creates or maintain habitat for other species
Ecological succession
The predictable replacement of one group of species by another group of species over time
Primary Succession
Ecological succession occurring on surfaces that are initially devoid of soil
Secondary Succession
The succession of plant life that occurs in areas that have been disturbed but have not lost their soil
Pioneer Species
A species that can colonize new areas rapidly and grow well in full sunshine
pioneer species increase in number and grow larger, however, they cause an
increased amount of shade on the ground. Because pioneer trees need full sunshine to grow, new seedlings of these trees cannot persist. More shade tolerant trees outcompete the pioneer species
Demography
The study of human populations and population trends
Immigration
the movement of people into a country
Emigration
the movement of people out of a country
Crude Birth Rate (CBR)
The number of births per 1000 individuals
Crude Death Rate (CDR)
The number of deaths per 1000 individuals per year
Doubling Time
the number of years it takes a population to double
How to know when population will double
70/growth rate
Total Fertility Rate (TFR)
An estimate of the average number of children that each women in a population will bear throughout her childbearing years
Replacement Level fertility
the total fertility rate required to offset the average number of deaths in a population to maintain the current population size
Developed Country
A country with relatively high levels of industrialization and income
Developing country
A country with relatively low levels of industrialization and income
Life Expectancy
The average number of years that an infant born in a particular year in a particular country can be expected to live, given the current average life span, and death rate in that country
How to calculate global population growth rate
CBR-CDR/10
How to measure a nation's growth rate
CBR+immigration-CDR +emigration/ 10
Doubling time
70/growth rate
Infant mortality
the number of deaths of children under 1 year of age
Child mortality
the number of deaths of children under the age of 5 per 1000 live births
Net migration rate
The difference between immigration and emigration in a giver year per 1000 ppl in a country
Net migration rate=nbr of immigrants per year/nbr of people in the population
...
Age structure diagram
a visual representation of the number of individuals within specific age groups for a country
Population pyramid
an age structure diagram that is the widest at the bottom, typical of developing countries
Population momentum
continued population growth after reduction measures have been implemented. Ex: china
Theory of demographic transition
the theory that as a country moves from a subsistence economy to industrialization and increased affluence it undergoes a predictable shift in population growth
Phase 1
CBR and CDR are the same, rather stable,
Phase 2
CDR decreases and CBR stays the same due to medical advances
Phase 3 stable population
CBR begins to fall. and families begin to have only a small number of children due to higher income
Phase 4: Declining Population Growth
high level of affluence and economic growth and CBR falls and there's a high level of elderly
IPAT equation
estimate the impact of human lifestyle on the environment impact= population, affluence, technology
Gross domestic Product (GDP)
a measure of one value of all products and service produced in one year in one country:
government and consumer spending,
exports-imports, and
investments
Increasing GDP means
is the best way to save the environment. Rise in income and falling birth rates. Wealthy countries can make make environmental improvements and increase their efficiency of resource use