population ecology part 1
DESCRIPTION
The human population will soon be over 7 billion people on Earth. Population Ecology This field of Biology deals with species populations and the population’s environment. A Population is the same species, same time, same place, and showing signs of reproduction. The human population will soon be over 7 billion people on Earth. We reached 7 billion as of October 2011…current figures are 7, --- --- ---,--- --- ---,--- --- ---. http://www.worldometers.info/world-population/TRANSCRIPT
Population Ecology Part 1
AP Biology Population Ecology Part 1 The human population will soon
be over 7 billion people on Earth.
Population Ecology This field of Biology deals with species
populations and the populations environment. A Population is the
same species, same time, same place, and showing signs of
reproduction. The human population will soon be over 7 billion
people on Earth. We reached 7 billion as of October 2011current
figures are 7, , , Population Human Population on Earth 8 Billion
(2024) According to the most recent United Nations estimates, the
human population of the world is expected to reach8 billion people
in the spring of 2024. 7 Billion (2011) According to the United
Nations, world population reached7 Billion on October 31, The US
Census Bureau made a lower estimate, for which the 7 billion mark
was onlyreached on March 12, Billion (1999) According to the United
Nations, the6 billion figure was reached on October 12,
1999(celebrated as theDay of 6 Billion). According to the U.S.
Census Bureau instead, the six billion milestone was reached on
July 22, 1999, at about 3:49 AM GMT. Yet, according to theU.S.
Census web site, the date and time of when 6 billion was reached
will probably change because the already uncertain estimates are
constantly being updated. Previous Milestones 5 Billion: 1987 4
Billion: 1974 3 Billion: 1960 2 Billion: 1927 1 Billion: 1804
Population Ecology It mainly focuses on Density (number of
organisms in a given area) and boundaries. Man made boundaries or
natural boundaries exist. Dispersion This term refers to where
within the boundaries are the organisms located. Population Density
Mark-Recapture Method
Measuring Density Mark-Recapture Method N= #Captured and marked in
first group x total of second group that is caught # Recaptured
from first time N is the estimated population size for that defined
area. Patterns of Dispersion
https://www.youtube.com/watch?v=6K128gg6Soc
Clumped This usually results from a need for nutrients, mating, or
employment. (humans, elephants, fish, some species of plants,
fungi) Uniform (evenly) This usually results from territoriality or
favorable environment. (snakes, nesting birds, some plants,) Random
There is no apparent reason seen in the dispersion pattern.
(dandelions, Dispersal Patterns Demography The study of population
sizes and distribution.
Growth This occurs by birth or immigration.(to enter into a new
area). Decline This occurs by death or emigration (to exit an
area). Life Tables Provides Age Specific Traits for cohorts
(individuals of the same age or demographic). These are expensive
and time consuming to produce. (Like the U.S. census.) Demography
Terminology
Births Immigration Population size Emigration Deaths Life Tables
and Cohorts Survivorship Curves - probability of newborn
individuals surviving to a particular ageThree basic types of
curves can exist in nature. Type I (Many young numerous middle few
old)(type of environment?) This environment favors the young and
usually indicates that the environment is favorable and these
organisms are usually at the top of food chain and there seems to
be extensive parental care and energy investment. Type II (Constant
decline) (type of environment?) This indicates that the environment
is relatively favorable but the organism may be a food source for
another organism. The parental cares is modest. Type III (Many
young few middle and old (type of environment?) This indicates a
harsh environment because most of the young die at an early age.
This indicates that they are a food source that is low on the food
chain as well as have practically no parental investment. Young are
left to fend for themselves. Figure 46.4a (Late loss) (Constant
loss) (early loss) Survivorship Curves E. Reproductive tables 1.
These tables are only concerned with females of reproductive age or
possibility. These are the only real individuals who will be able
to impact a population size since it is the female who provides the
birth. (Low # of females indicates a threatened or dying
population; High # indicates a thriving population.) Population
Ecology Part 2
AP Biology Population Ecology Part 2 21 Important concepts from
previous units:
Traits within cells or organisms are directly associated with
inherited DNA (genes). DNA is inherited from the parents by
fertilization occurring between a sperm and egg. (sexual
reproduction) Positive feedback loops enhance a process that is
already in action. DNA Inherited 23 Expression of DNA to create
traits
24 Life Histories A life history can tell a lot about a species
fitness. Traits needed for survival in a particular environment can
be determined. Two types of life histories can typically be seen:
Semelparity (Big Bang) Reproduce one time with huge numbers of
offspring. Organism usually dies after reproducing, so it went out
with a Big Bang. Tremendous amounts of time, energy, and resources
invested in making numerous offspring. This type of history usually
indicates a harsh environment and low survival rates. Examples:
Salmon or Century Plant Century Plant 26 Natural selection is very
obvious with Semelparitystrongest survive.
Iteroparity - Repeated Reproduction year after year. (Applies to
most organisms usually.) This history indicates a favorable
environment and good survival rates. Modest time, energy, resource
investment are required. Environmental Conditions and survival
rates? Environment is directly related to time, energy involved,
resources available. Compromises (When, how often, how
many)(Natural selection?) Natural selection is very obvious with
Semelparitystrongest survive. Natural selection with Iteroparity is
directly related to competition. Population Growth Models
Exponential Growth Models (Ideal Growth) Involves r-selection
species. (r- think rapid growth)(A.K. A. Density independent) There
population size is related to resources not number of organisms.
Produces a J curve graph. Environment has unlimited resources.
(Good for ideal growth) Occurs mainly in a new environments and
pioneer species such as bacteria, lichens, and mosses. (They are
the first organisms to colonize the new environment.) Population
Growth Characteristics
Exponential Growth-as a population gets larger, it also grows
faster (J-shaped curve) (WHY?) Elephant population 1900 1920 1940
1960 1980 Year
Exponential Growth 8,000 6,000 Elephant population 4,000 2,000 1900
1920 1940 1960 1980 Year 31 This is in areas that are just formed
like Hawaii was millions of year ago. (Hawaii started as barren
rock, until the pioneers arrived and began to make soil. The soil
enabled plants to grow. The seeds of the plants arrived in the bird
dropping of birds that stopped while migrating to feed on the
mosses and lichens. Larger plant roots sped up soil formation to
allow for larger plants.) Hawaii millions of years ago
33 Pioneer species begin to colonize (lichens and mosses)
34 Then over time, grasses begin to grow.
35 Then over time, shrubs will appear and they will be followed by
trees.
36 Hawaii today 37 = (bN) (dN) (birth rate death rate) (This is
equal to rN.)
N/t = B D (Means change in population is equal to births deaths in
that time.) = (bN) (dN) (birth rate death rate) (This is equal to
rN.) = rN; r= b d (if r is positive = growth greater; if r is
negative = death greater) ZPG (Zero Population Growth) (r= 0)
Intrinsic growth = rmax (Population is growing as fast as
possible/doubling. This is seen as the curve begins to make a
straight up curve.) r=rate of increase =b-d rN-rate of increase x
number in population
B = bN b(per capita birth rate) N (population size) B expected
number of birth expected based on the population size D=dN d(per
capita death rate) D expected number of death expected based on the
population size bN-dN=rN r=rate of increase =b-d rN-rate of
increase x number in population Current population growth rate
Formulas related to population growth
Growth rate (r) = birth rate (b) - death rate (d) # of births /
total # of deaths / total Practice Problem: In research on beetles,
you estimate that the populations size is Over the course of a
month, you record 400 births and 150 deaths. What is the growth
rate (r)? Population growth = rN (r = growth rate, N = original
population size) Calculate the population growth of the beetle
population. US Population size in 2013 (N) = approximately 316
million
Number of births in the US in 2013 (B) = approximately 4.1 million
Number of deaths in the US in 2013 (D) = approximately 2.5 million
What is theper capitabirth rate ("b") for the US in 2013? b=4.1
milliin /316 mil=.013=13/1000 What is theper capitadeath rate ("d")
for the US in 2013? d=2.5million/316 million = .008 = 8/1000
Exponential Ideal Growth
42 Intrinsic Growth 43 Logistic Growth Model (Realistic
growth)
1. Involves K-selection species usually. (K refers to a population
that is hovering around the carrying capacity which is represented
by K) (Density dependent) These species numbers are about number
because there are limited resources because the species is near the
carrying capacity for that environment. 2. Produces an S curve
graph. (snakes around the carrying capacity line) 3. Environment
has limited resources; that is why organisms stay around the K. a.
More organisms than K means damage will be done to the environment.
b. More damage done to environment can cause K to drop even
farther. This can be an example of a positive feedback loop. c.
Wars, disease, and famine breakout in a population to bring numbers
down below K. (Extinction is possible? depends on damage to
environment and K.) Carrying Capacity-the number of one species an
environment can support over long periods of time.(S-shaped curve
Logistic realistic growth
46 4. dN/dt = rN (K-N/K) K-Nthe number of individuals that
environment can still support K-N/Kthe fraction of K still
available for growth (As a population N approaches K, K-N
approaches zero.) Meaning when K- N is equal to 0 you are at the
carrying capacity for that environment.When K- N becomes 0, the
whole equation becomes 0. Before this time, a population is
experiencing exponential growth so you have r maxed. Logistic
Growth 48 5. Lag time (This accounts for the overshoot
5. Lag time (This accounts for the overshoot.) It takes time to
begin to see the effects. (So the line goes above K and this is
when death, war, disease, and famine accelerate.) 6. Allee effect
This situation occurs when you have a small number of
organisms.This low number causes inbreeding to occur and then this
results in no variation for a gene pool and this leads to increased
genetic diseases that can be lethal to accumulate in the already
small population and then the population enters what is referred to
as the Extinction Vortex.It is extremely difficult to break out of
the vortex. (Like a black whole of extinction.) Allee affect and
the Extinction Vortex
Small population Genetic drift Inbreeding Lower reproduction Higher
mortality Loss of genetic variability Reduction in individual
fitness and population adaptability Smaller population 50