2 Populations 3. A population is a group of individuals of the
same species living in an area
Slide 4
Distribution Patterns Uniform distribution results from intense
competition or antagonism between individuals. Random distribution
occurs when there is no competition, antagonism, or tendency to
aggregate. Clumping is the most common distribution because
environmental conditions are seldom uniform. 3 Populations disperse
in a variety of ways that are influenced by environmental and
social factors
Slide 5
Fig. 52.1, Campbell & Reece, 6 th ed. Clumped distribution
in species acts as a mechanism against predation as well as an
efficient mechanism to trap or corner prey. It has been shown that
larger packs of animals tend to have a greater number of successful
kills. What causes these populations of different organisms to
clump together?
Slide 6
Population Dispersal In rare cases, long- distance dispersal
can lead to adaptive radiation For example, Hawaiian silverswords
are a diverse group descended from an ancestral North American
tarweed 5
Slide 7
The Spread of the Africanized Honey Bee When did they first
arrive in the Americas? How long did it take for them to expand
their range into the US? How can you explain their success in
expanding their territory? 6
Slide 8
7 Estimating Population Size The Mark-and-Recapture Technique
1. 2. 3.
Slide 9
Estimating Population Size The Mark-and-Recapture Technique
8
Slide 10
Lets Try an Example! 9 Twenty individuals are captured at
random and marked with a dye or tag and then are released back into
the environment. Therefore s = # of animals marked = 20 At a later
time a second group of animals is captured at random from the
population
Slide 11
Lets Try an Example! 10
Slide 12
11 Which method would you use? 1. To determine the number of
deer in the state of Virginia? 2. To determine the number of
turkeys in a county? 3. To determine the number of dogs in your
neighborhood? 4. To determine the number of ferrel cats in your
neighborhood?
Slide 13
Survivorship curves What do these graphs indicate regarding
species survival rate & strategy? 025 1000 100 Human (type I)
Hydra (type II) Oyster (type III) 10 1 50 Percent of maximum life
span 10075 Survival per thousand I.High death rate in
post-reproductive years II.Constant mortality rate throughout life
span III.Very high early mortality but the few survivors then live
long (stay reproductive)
Slide 14
1,000 III II I 100 10 1 10050 0 Percentage of maximum life span
Number of survivors (log scale) Ideal Survivorship Curves
Slide 15
Population Growth Curves 14 d = delta or change N = population
Size t = time B = birth rate D =death rate
Slide 16
Population Growth Models
Slide 17
Exponential Growth Curves 16 d = delta or change N = Population
Size t = time r max = maximum per capita growth rate of population
Population Size, N Time (hours) Growth Rate of E. coli
Slide 18
Logistic Growth Curves 17
Slide 19
Logistic Growth Curves 18 d = delta or change N = Population
Size t = time K =carrying capacity r max = maximum per capita
growth rate of population
Slide 20
Comparison of Growth Curves 19
Slide 21
Growth Curve Relationship 20
Slide 22
Examining Logistic Population Growth Graph the data given as it
relates to a logistic curve. Title, label and scale your graph
properly. 21
Slide 23
Examining Logistic Population Growth 22 Hypothetical Example of
Logistic Growth Curve K = 1,000 & r max = 0.05 per Individual
per Year
Slide 24
Population Reproductive Strategies r-selected (opportunistic)
Short maturation & lifespan Many (small) offspring; usually 1
(early) reproduction; No parental care High death rate K-selected
(equilibrial) Long maturation & lifespan Few (large) offspring;
usually several (late) reproductions Extensive parental care Low
death rate
Slide 25
24 Some populations overshoot K before settling down to a
relatively stable density Some populations fluctuate greatly and
make it difficult to define K How Well Do These Organisms Fit the
Logistic Growth Model?
Slide 26
Percent of population Rapid growth Afghanistan Slow growth
United States No growth Italy Male Female Age 85+ 8084 7579 7074
6569 6064 5559 5054 4549 4044 3539 3034 2529 2024 1519 1014 59 04
Age 85+ 8084 7579 7074 6569 6064 5559 5054 4549 4044 3539 3034 2529
2024 1519 1014 59 04 100 88888866666644444422222200 Age Structure
Diagrams: Always Examine The Base Before Making Predictions About
The Future Of The Population
Slide 27
Natural Selection This includes describing how organisms
respond to the environment and how organisms are distributed.
Events that occur in the framework of ecological time (minutes,
months, years) translate into effects over the longer scale of
evolutionary time (decades, centuries, millennia, and longer).
26
Slide 28
Natural Selection 27
Slide 29
Natural Processes 28
Slide 30
Finch Beak Size or Shape 29
Slide 31
Modes of Selection 30
http://gregladen.com/blog/2007/01/the-modes-of-natural-selection/
Slide 32
Modes of Selection Disruptive- produces a bi- modal curve as
the extreme traits are favored Stabilizing-reduces variance over
time as the traits move closer to the mean Directional-favors a
phenotypic trait (selected by the environment)
Slide 33
Scenario 32 These photographs show the same location on Captiva
Island following Hurricane Charley. What would happen to a
population of birds who derive their diets from the tree tops? The
population had a wide range of beak sizes. What would happen to the
population gene pool over time if the new environment favored
smaller beaks? Over time, which beak would be most represented in
the population of birds?
Slide 34
Selection Diagrams 33 ABC
Slide 35
Beak Selection After Hurricane 34
Slide 36
Hydrangea Flower Color Hydrangea react to the environment and
ultimately display their phenotype based on the pH of their soil.
Hydrangea flower color is affected by light and soil pH. Soil pH
exerts the main influence on which color a hydrangea plant will
display. 35
Slide 37
Biogeographic Realms 36
Slide 38
Introduced Species Whats the big deal? These species are free
from predators, parasites and pathogens that limit their
populations in their native habitats. These transplanted species
disrupt their new community by preying on native organisms or
outcompeting them for resources. 37
Slide 39
Guam: Brown Tree Snake The brown tree snake was accidentally
introduced to Guam as a stowaway in military cargo from other parts
of the South Pacific after World War II. Since then, 12 species of
birds and 6 species of lizards the snakes ate have become extinct.
Guam had no native snakes. 38 Dispersal of Brown Tree Snake
Slide 40
Southern U.S.: Kudzu Vine The Asian plant Kudzu was introduced
by the U.S. Dept. of Agriculture with good intentions. It was
introduced from Japanese pavilion in the 1876 Centennial Exposition
in Philadelphia. It was to help control erosion but has taken over
large areas of the landscape in the Southern U.S. 39
Slide 41
New York: European Starling From the New York Times, 1990 The
year was 1890 when an eccentric drug manufacturer named Eugene
Schieffelin entered New York City's Central Park and released some
60 European starlings he had imported from England. In 1891 he
loosed 40 more. Schieffelin's motives were as romantic as they were
ill fated: he hoped to introduce into North America every bird
mentioned by Shakespeare. Skylarks and song thrushes failed to
thrive, but the enormity of his success with starlings continues to
haunt us. This centennial year is worth observing as an object
lesson in how even noble intentions can lead to disaster when
humanity meddles with nature. 40
Slide 42
New York: European Starling From the New York Times, 1990
(cont.) Today the starling is ubiquitous, with its purple and green
iridescent plumage and its rasping, insistent call. It has
distinguished itself as one of the costliest and most noxious birds
on our continent. Roosting in hordes of up to a million, starlings
can devour vast stores of seed and fruit, offsetting whatever
benefit they confer by eating insects. In a single day, a cloud of
omnivorous starlings can gobble up 20 tons of potatoes. 41
Slide 43
42 Zebra Mussels The native distribution of the species is in
the Black Sea and Caspian Sea in Eurasia. Zebra mussels have become
an invasive species in North America, Great Britain, Ireland,
Italy, Spain, and Sweden. They disrupt the ecosystems by monotypic
(one type) colonization, and damage harbors and waterways, ships
and boats, and water treatment and power plants.
Slide 44
43 Zebra Mussels Water treatment plants are most impacted
because the water intakes bring the microscopic free-swimming
larvae directly into the facilities. The Zebra Mussels also cling
on to pipes under the water and clog them. This shopping cart was
left in zebra mussel-infested waters for a few months. The mussels
have colonized every available surface on the cart. (J. Lubner,
Wisconsin Sea Grant, Milwaukee, Wisconsin.)
Slide 45
44 Zebra Mussel Range
Slide 46
Slide 47
INQUIRY: Does feeding by sea urchins limit seaweed
distribution? W. J. Fletcher of the University of Sydney, Australia
reasoned that if sea urchins are a limiting biotic factor in a
particular ecosystem, then more seaweeds should invade an area from
which sea urchins have been removed. 46
Slide 48
INQUIRY: Does feeding by sea urchins limit seaweed
distribution? Seems reasonable and a tad obvious, but the area is
also occupied by seaweed-eating mollusc called limpets. What to do?
Formulate an experimental design aimed at answering the inquiry
question. 47
Slide 49
Predator Removal 48
Slide 50
Predator Removal 49 Removing both limpets and urchins or
removing only urchins increased seaweed cover dramatically
Slide 51
Predator Removal 50 Almost no seaweed grew in areas where both
urchins and limpets were present (red line), OR where only limpets
were removed (blue line)
Slide 52
Created by: Susan Ramsey Virginia Advanced Study Strategies
Notable contributions by S.Meister