1. Ecology Population Ecology
This is the second portion of the Ecology unit.

2. Populations
A population is a group of individuals of the same species living in an area
These iguanas live in trees over a River in the North East corner of Costa Rica. Like many lizards, iguanas are cold-blooded, which means they don't generate their own heat. However, these animals have adapted to live in a wide range of environments. While usually found in rainforest or near water, species of iguanas can be found in the desert and in other land environments where they get their water from their food sources.
Population ecology focuses on factors affecting population size over time.
Density is the number of individuals per unit area or volume
Dispersion is the pattern of spacing among individuals within the boundaries of the population 3.

3. Distribution Patterns
Populations disperse in a variety of ways that are influenced by environmental and social factors
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, it aides in reproduction and animal behavior patterns
Uniform and random distributions are relatively rare and occur only where environmental conditions are fairly uniform. A uniform distribution results from intense competition or antagonism between individuals.
Random distribution occurs when there is no competition, antagonism, or tendency to aggregate. The conditions are uniform. It is rare for all these conditions in the environment to be met.
Clumping is the most common distribution because environmental conditions are seldom uniform, reproductive patterns favor clumping, and animal behavior patterns often lead to congregation. The optimum density for population growth and survival is often an intermediate one; undercrowding can be as harmful as overcrowding.

4. What causes these populations of different organisms to clump together?
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.
Fig. 52.1, Campbell & Reece, 6th ed.

5. Population Dispersal
Natural range expansions show the influence of dispersal on distribution
For example, cattle egrets arrived in the Americas in the late 1800s and have expanded their distribution
They sure have! They are quite the pest in Texas.

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
Adaptive radiation is the diversification of a group of organisms into forms filling different ecological niches. Some classics are: Darwin’s finches and the marsupials of Australia.

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?
First arrived? Researchers brought the African bees to Brazil in the 1950s in an attempt to improve the productivity of Brazilian bees.
How long to reach US? 40 years! A large wild population quickly developed and spread through South America, Central America and Mexico. In the 1990's, the Africanized honey bee was identified in Texas and has since spread though the southwest US.
Why successful? Many correct answers including: African bees produce more offspring, defend their nests much more fiercely and in greater numbers and are more likely to abandon the nest when threatened by predators or adverse environmental conditions.

8. Small Geographic Range
Most species have a small geographic range

9. Species with a Large Geographic Range: Moss
Moss Tetraphis- is a unique moss that has only 4 peristome (mouth or opening of an organ) teeth (most mosses have 8 to 64). It reproduces asexually when it is not fruiting. These adaptations have given this moss a large geographic range in which to inhabit.

10. Interactions
Interactions between organisms and their environments determine abundance and distribution of organisms. Ask students to postulate as to why the range of kangaroos follows this pattern.

11. Estimating Population Size The Mark-and-Recapture Technique2. 1.
Count the total # of individuals, easy if the organisms are large and area is not too large.
Divide the area into # of quadrants and count the number of individuals in several of quadrants and then estimate the entire area.
Mark-and-recapture technique: A limited number of individual (e.g. 20) are captured at random and marked with a dye or tag and then are released back into the environment. At a later time a second group of animals is capture at random from the population and the percentage of marked individuals determined. Now if 10% of the animals in this second group is recaptured, then the original 20 represented 10% of the population and the population then is 200. 3.

12. Estimating Population Size The Mark-and-Recapture Technique
There’s a simple formula for estimating the total population size
𝑠 𝑁 = 𝑥 𝑛
s = Number of individuals marked and released in 1st sample
x = Number of individuals marked and released in 2nd sample
n = Total number of individuals in 2nd sample
N = Estimated population size
Rearrange to get: 𝑁= 𝑠𝑛 𝑥
Emphasize that this method comes with a whopping assumption! Namely, that marked individuals have the same probability of being captured as unmarked individuals.

13. Therefore s = # of animals marked = 20
Let’s Try an Example!
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
Emphasize that this is a simple proportionality and they should “expect easy math”! In other words, the numbers won’t be too scary or abstract.

14. Let’s Try an Example!
Some will already be marked, say 10 individuals were marked out of 35 that were captured the second time. We now know n = 35 and x = 10
So, apply the formula and solve for the estimated population size:
𝑁= 𝑠𝑛 𝑥 = = = 70
Therefore, N =70 as a population estimate

15. Which method would you use?
1. To determine the number of road runners in the state of New Mexico?
2. To determine the number of bears in a county?
3. To determine the number of dogs in your neighborhood?
4. To determine the number of ferrel cats in your neighborhood?
Use the mark-recapture method to estimate the population since the area is vast.
2. Use the quadrant method from various areas around Virginia to estimate the population.
3. & 4. Simply count them since the area is small and the population numbers will be low.

16. Survivorship curves
What do these graphs indicate regarding species survival rate & strategy? 25
1000
100
Human
(type I)
Hydra
(type II)
Oyster
(type III) 10 1 50
Percent of maximum life span 75
Survival per thousand
I. High death rate in post-reproductive years
II. Constant mortality rate throughout life span
Type I curve is flat at the start, reflecting low death rates during early and middle life, then drops steeply as death rates increase among older age groups. Humans and many other large mammals that produce few offspring but provide them with good care often exhibit this kind of curve.
Type II curves are intermediate, with a constant death rate over the organism’s life span. This kind of survivorship occurs in Belding’s ground squirrels and some other rodents, various invertebrates, some lizards, and some annual plants.
Type III curve drops sharply at the start, reflecting very high death rates for the young, but then flattens out as death rates decline for those few individuals that have survived to a certain critical age. This type of curve is usually associated with organisms that produce very large numbers of offspring but provide little or no care, such as long–lived plants, many fishes, and marine invertebrates. An oyster, for example, may release millions of eggs, but most offspring die as larvae from predation or other causes. Those few that survive long enough to attach to a suitable substrate and begin growing a hard shell will probably survive for a relatively long time.
III. Very high early mortality but the few survivors then live long (stay reproductive)

17. Population Growth Curves
𝑑𝑁 𝑑𝑡 =𝐵−𝐷
d = delta or change
N = population Size
t = time
B = birth rate
D =death rate
More graphical analysis questions: Ask students how many more deaths occurred in 2001 than births?
Qualitative Analysis: Locate both time intervals. In 2000, the population of perch was 16,000 in 2001, the population declined to 12,00, therefore 4,000 more deaths occurred than there were births. Don’t let students think that it is as simple as 4,000 perch “died”, make sure they understand that births didn’t cease!
Quantitative Analysis: 𝑑𝑁 𝑑𝑡 =𝐵−𝐷∴ =12,000−16,000=−4,000, therefore 4,000 more deaths than births between 2000 and 2001.

18. Population Growth Curves
How many more deaths occurred in 2001 than births?
Locate both time intervals. In 2000, the population of perch was 16,000 in 2001, the population declined to 12,00, therefore 4,000 more deaths occurred than there were births. It’s not as simple as 4,000 perch “died”, births don’t cease!
𝑑𝑁/𝑑𝑡=𝐵−𝐷∴ =12,000−16,000=−4,000, therefore 4,000 more deaths than births between 2000 and 2001.
More graphical analysis questions: Ask students how many more deaths occurred in 2001 than births?
Qualitative Analysis: Locate both time intervals. In 2000, the population of perch was 16,000 in 2001, the population declined to 1600, therefore 4,000 more deaths occurred than there were births. Don’t let students think that it is as simple as 4,000 perch “died”, make sure they understand that births didn’t cease!
Quantitative Analysis: 𝑑𝑁 𝑑𝑡 =𝐵−𝐷∴ =12,000−16,000=−4,000, therefore 4,000 more deaths than births between 2000 and 2001.

19. Population Growth Models
Exponential model (blue) idealized population in an unlimited environment (J-curve); can’t continue indefinitely. r-selected species (r = per capita growth rate) 𝑑𝑁 𝑑𝑡 = 𝑟 𝑚𝑎𝑥 𝑁 Logistic model (red) considers population density on growth (S-curve), carrying capacity (K): maximum population size that a particular environment can support; K-selected species 𝑑𝑁 𝑑𝑡 = 𝑟 𝑚𝑎𝑥 𝑁 𝐾−𝑁 𝐾
WOW! 1 bacterium (reproducing every 20 minutes), could produce enough bacteria to form a layer over the entire surface of the Earth 1 foot deep!

20. Exponential Growth Curves
Growth Rate of E. coli
𝒅𝑵 𝒅𝒕 = 𝒓 𝒎𝒂𝒙 𝑵
d = delta or change
N = Population Size
t = time
rmax = maximum per capita growth rate of population
Population Size, N
One of the most common examples of exponential growth deals with bacteria.  Bacteria can multiply at an alarming rate when each bacteria splits into two new cells, thus doubling.  For example, if we start with only one bacteria which can double every hour since it reproduces asexually, by the end of one day we will have over 16 million bacteria.
Time (hours)

21. Logistic Growth Curves
In the logistic population growth model, the per capita rate of increase (rmax) declines as carrying capacity (K) is reached
The logistic model starts with the exponential model and adds an expression that reduces per capita rate of increase as N approaches K
𝑑𝑁 𝑑𝑡 = 𝑟 𝑚𝑎𝑥 𝑁 𝐾−𝑁 𝐾
Keep emphasizing that “logistic” means as in “logarithm”.

22. Logistic Growth Curves
𝑑𝑁 𝑑𝑡 = 𝑟 𝑚𝑎𝑥 𝑁 𝐾−𝑁 𝐾
What is the carrying capacity (K ) for AIDS according to this graph?
Ask: What is the carrying capacity (K ) for AIDS according to this graph? 45,000 as of 1995.
d = delta or change
N = Population Size
t = time
K =carrying capacity
rmax = maximum per capita growth rate of population

23. Comparison of Growth Curves
Exponential population growth results in a J-shaped curve. The J-shaped curve of exponential growth characterizes some rebounding populations. For example, the elephant population in Kruger National Park, South Africa, grew exponentially after hunting was banned. The logistic model describes how a population grows more slowly as it nears its carrying capacity. Exponential growth cannot be sustained for long in any given population.
The logistic model of population growth produces a sigmoid (S-shaped) curve. A more realistic population model limits growth by incorporating carrying capacity. Carrying capacity (K) is the maximum population size the environment can support. Carrying capacity varies with the abundance of limiting resources. This figure shows population growth predicted by the logistic model. The growth of laboratory populations of paramecia fits an S-shaped curve. These organisms are grown in a constant environment lacking predators and competitors.
Examples?

24. Growth Curve Relationship
After the curve has leveled off, births and deaths are in balance and the population has zero population growth. This occurs because environmental limitations become increasingly effective in slowing population growth as the population density rises. When the density approaches the carrying capacity, the limitation becomes severe. A density dependent limitation, (K-N)/K, is one whose effect is determined by the density of the very population.

25. Examining Logistic Population Growth
Graph population vs. time as it relates to a logistic curve. Title, label and scale your graph properly.
Have students graph Number of Individuals or Population Size (N) vs. Time in Years and identify where and when the carrying capacity is reached for the hypothetical population.
Emphasize to students that the “versus” terminology is their friend since it is correctly states as “y vs. x” or “rise vs. run” if they are more comfortable with that terminology. They should know this from math class, but this protocol is not always followed among casually created materials.
So in this case, “Number of Individuals” (y-axis) vs. “Time (years)” are their y and x axes labels. Don’t move to the next slide until you’ve surveyed their graphs for the following: Proper title (Don’t let them get away with just restating the axes), proper labels on axes (units), proper scale, proper curve modeling as opposed to connecting data points “dot to dot” like they did in elementary school!
An example graph follows on the next slide (not in their handout).

26. Examining Logistic Population Growth
Hypothetical Example of Logistic Growth Curve
K = 1,000 & rmax = 0.05 per Individual per Year

27. 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
Emphasize that these r-selected and opportunistic are synonyms as are K- selected and equilibrial. It’s the synonyms that will give students fits when they are reading and interpreting test questions!

28. How Well Do These Organisms Fit the Logistic Growth Model?
Have students examine the graph of Paramecium. What is the carrying capacity of the population in the lab? About 900.
How long does it take the Paramecium to reach K? About 10 days.
Have students examine the graph of the Daphnia.
What is the carrying capacity of the population in the lab? About 90.
How long does it take the Paramecium to reach K? About 135 days.
Some populations overshoot K before settling down to a relatively stable density
Some populations fluctuate greatly and make it difficult to define K

29. Hopefully students have learned about Galileo before reaching high school. His troubles with the church aside, he’s famous for many things, among them dropping two balls of different masses from the Leaning Tower of Pisa in 1589 (not as leaning then!) to demonstrate that their time of descent was independent of their mass. David Scott a NASA Apollo 15 astronaut repeated this experiment during a moon walk. (It’s all about surface area as it relates to mass and air resistance here on earth!)
IF you can get to Utube, this is a great short video of this fundamental truth. A vacuum pump has been used to remove the air from two glass tubes to eliminate the air, thus eliminating air resistance! 29

30. Lemmings DO NOT Commit Suicide!
Where the Lemming Suicide Myth Started
In 1958 Disney released a nature documentary called White Wilderness in which they filmed a fake migration sequence with imported collared lemmings. They placed lemmings on a spinning turntable, which was filmed from different angles. They then herded the lemmings off a small cliff and into a river.
This would make for a more interesting movie but we know now that lemmings don’t commit suicide, they simply migrate and have large fluctuations in their population.
Read more at Suite101: What is a Lemming and Do They Commit Suicide?: Do These Small Rodents Follow Each Other Over Cliffs to Their Death? | Suite101.com | 30

31. Age Structure Diagrams: Always Examine The Base Before Making Predictions About The Future Of The Population
Rapid growth
Afghanistan
Slow growth
United States
No growth
Italy
Male
Female
Age
85+
80–84
75–79
70–74
65–69
60–64
55–59
50–54
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
5–9
0–4
Male
Female
Age
85+
80–84
75–79
70–74
65–69
60–64
55–59
50–54
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
5–9
0–4
Male
Female
Age-structure pyramids for the human population of three countries (data as of 2009). Emphasize to students that they should start their analysis at the BASE of these diagrams since that represents the most current population. Also emphasize they respect the vertical line on these diagrams that delineate male vs. female. Briefly explain why the predictions above each graph are likely to hold true. 10 8 6 4 2 2 4 6 8 10 8 6 4 2 2 4 6 8 8 6 4 2 2 4 6 8
Percent of population
Percent of population
Percent of population 31

32. Predicting Populations
Sex and the Single Guppy
LO 1.3 The student is able to apply mathematical methods to data from a real or simulated population to predict what will happen to the population in the future. SP 2.2 The student can apply mathematical routines to quantities that describe natural phenomena
Sex and the Single Guppy can be found at the PBS website: you’ll need to have the Adobe Shockwave Plugin installed (ask the tech folks to do it if you can’t). You should select two different variables Guppy Color Types and Predator Species and Numbers and run the simulation once. Then make a prediction about what would happen if you changed the guppy color and left the predator species the same. Make the changes and run the simulation. How did the simulation compare to your prediction. Repeat for the predator species (make a prediction) and then run the simulation again and analyze the results.

33. 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).
LO 1.2 The student is able to evaluate evidence provided by data to qualitatively and quantitatively investigate the role of natural selection in evolution
SP 2.2 The student can apply mathematical routines to quantities that describe natural phenomena
SP 5.3The student can evaluate the evidence provided by data sets in relations to a particular scientific question

34. Natural Selection
Big Idea 1: The process of evolution drives the diversity and unity of life
EU 1. A change in the genetic makeup of a population over time is evolution
LO 1.2
The student is able to evaluate evidence provided by data to qualitatively and quantitatively investigate the role of natural selection in evolution
SP 2.2 The student can apply mathematical routines to quantities that describe natural phenomena
SP 5.3The student can evaluate the evidence provided by data sets in relations to a particular scientific question
EK 1.A.2 Natural selection acts on phenotypic variations in populations. The environment determines what traits in a population are naturally selected.

35. Natural Processes
Big Idea 1: The process of evolution drives the diversity and unity of life
EU 1.C Life continues to evolve within a changing environment.
EU 1.D The origin of living systems is explained by natural processes.
Long before humans or organisms inhabited the earth, natural processes continually changed the environment. These natural processes caused change in the landscape of the earth as well as changes in the atmosphere and the gases and energy available to life.

36. Finch Beak Size or Shape
Big Idea 1: The process of evolution drives the diversity and unity of life
EU 1.C Life continues to evolve within a changing environment.
EK 1.C.3 Populations of organisms continue to evolve.
So, let’s look at Darwin’s famous finches and some work done by Peter and Rosemary Grant. “Trees on the islands produce both small, soft seeds that are easy to eat; and large tough ones that require large beaks to crack open and eat. In 1977 the islands suffered a drastic drought, with the trees producing fewer seeds of all kinds”.
Ask students: What do you think happened to the average beak size among the ground finches?
Answer: large beaked birds were more successful resulting more of them surviving and reproducing so the average beak size increased significantly
Then ask: Does this mean that small beaks disappeared completely? Etc…

37. Modes of Selection
See if students have the math capability and/or vocabulary to describe what is going on with respect to natural selection before your explain it to them.
Disruptive selection, also called diversifying selection (synonyms again!), extreme traits are favored over intermediate values. The variance of the trait increases and the population is divided into two distinct groups (statistically we call this bi-modal).
Stabilizing or ambidirectional selection, This is probably the most common mechanism of action for natural selection and reduces variance.
Directional selection a single phenotype is favored, causing continuous shift in one direction (skew). Under directional selection, the advantageous allele increases in frequency independently of its dominance relative to other alleles; that is, even if the advantageous allele is recessive., it will eventually become fixed. Directional selection occurs most often under environmental changes and when populations migrate to new areas with different environmental pressures

38. 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)
This is an alternate graphic that shows the same modes of selection.

39. Scenario
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?
Stripped Vegetation: On North Captiva Island, the extreme winds in Hurricane Charley's eyewall stripped the leaves from trees leaving bare limbs. This is reminiscent of the aftermath of Category-5 Hurricane Andrew in south Florida where lush vegetation was extensively removed.
LO 4.23 The student is able to construct explanations of the influence of environmental factors on the phenotype of an organism.

40. Selection Diagrams A B C
Answer:: Directional Selection because the environment is selecting for small beaks based on the new food source and acquisition of that source gives an animal with small beaks more free energy. A B C

41. Beak Selection After Hurricane
Big Idea 1: The process of evolution drives the diversity and unity of life
EU 1.C Life continues to evolve within a changing environment.
EK 1.C.3 Populations of organisms continue to evolve.
LO 1.25 The student is able to describe a model that represents evolution within a population.
Directional Selection: One hypothesis may be that beak size in the population over time may increase. Thus the gene pool would consist of more alleles for large beaks than smaller beaks.
So let’s look at Darwin’s famous finches. If nothing happens (there is no disturbance for a long period of time) and the island tree’s grow taller and taller over thousands of years, what might happen to beak size?
Does that mean that all small beaks have disappeared completely? Does that mean that small beaks could no rebound after some other natural environmental change that favors them?

42. Biogeography & Distribution of Species
Serves as a starting point to understanding limits on distribution of species
Species absent
because
Yes No
Dispersal limits distribution?
Behavior limits distribution?
Biotic factors (other species) limit distribution?
Abiotic factors limit distribution?
Area inaccessible
or insufficient time
Habitat selection
Predation, parasitism, competition, disease
Water Oxygen
Salinity
pH Soil nutrients, etc.
Temperature Light
Soil structure
Fire Moisture, etc.
Chemical
factors
Physical
Suggested Simulations for students to practice with concepts within this unit of study:
Animal Behavior: Behavior/modules.htm
Population Simulations:
Chi:
Phet: Biology-> Natural Selection Pinko Probability
Ecology & Behavior
Global Environment
Chi Square: Fruit Fly Lab

43. 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.
LO 3.19 The student is able to describe the connection between the regulation of gene expression and observed differences between individuals in a population.
LO 4.24 The student is able to predict the effects of a change in environmental factor on the genotypic expression of the phenotype.
Hydrangeas are fascinating in that, unlike most other plants, the color of their flowers can change dramatically. It would be nice if one could change the color of hydrangeas as easily as it changes in this picture. But for most of us, it is not that easy. The people who have the most control over the color of their hydrangeas are those who grow them in containers. It is much easier to control or alter the pH of the soil in a container than it is in the ground.
Only Hydrangea macrophylla or serrata species have the ability to change color based on the soil pH. There are some genetically altered cultivars that may stay pink or blue, but it is the exception rather than the rule.

44. Fish And Maintaining Homeostasis In Various Water Conditions
Fish and other aquatic animals deal with changing environments in part due to nature and in part due to human interactions.
Pressure- their bladder fills with gas to equalize internal pressure
LO 2.25 The student can construct explanations based on scientific evidence that homeostatic mechanisms reflect continuity due to common ancestry and/or divergence due to adaptation in different environments.
LO 2.26 The student is able to analyze data to identify phylogenetic patterns or relationships, showing that homeostatic mechanisms reflect both continuity due to common ancestry and change due to evolution in different environments.
LO 2.27 The student is able to connect differences in the environment with the evolution of homeostatic mechanisms.
Homeostatic mechanisms:
Homeostatis in mammals

45. Biogeographic Realms
Why do species live where they live? What factors influence dispersal patterns and ranges? Reward reasonable answers!

46. Introduced Species What’s 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.
Introduced species are also called non-native or exotic species and are those that humans move intentionally or accidentally from the species’ native region to new geographic regions.

47. 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.
As humans have increased their control over transportation, even air transportation, transporting stowaways and introducing nonnative species continues to be a huge concern. Hawaii struggles with this more than any other state in our country.
Dispersal of Brown Tree Snake

48. 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.
Kudzu is a huge concern and is spreading very rapidly!

49. 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.
 In the intervening hundred plus years the starling population has grown to an estimated million birds all across the US.

50. 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.
The coloration is magnificent from egg to adult! We can fully understand why Shakespeare included them in his works!

51. 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.
The bottom photo is of a Zebra mussel-encrusted Vector Averaging Current Meter from Lake Michigan.

52. 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.
This is alarming!
(J. Lubner, Wisconsin Sea Grant, Milwaukee, Wisconsin.)

53. Zebra Mussel Range
They are still spreading at an alarming rate.

54. This slide shows how a population of fish distributes itself over a temperature range. Some of this population is able to exist at the temperature extremes modeled at the outermost points of the curve. This variation is important for population survival especially in the event of climate change. Remind them that pH, light intensity, and other abiotic factors can play a role in survival. Population, like most interactions, is complex and variation give a population the highest chance of survival over generations since many combinations of abiotic and biotic factors can influence survival.

55. Snakehead Fish
During all life stages, snakeheads compete with native species for food and habitat.
As juveniles, they eat zooplankton, insect larvae, small crustaceans, and the young of other fishes.
As adults, they feed on other fishes, crustaceans, frogs, small reptiles, and sometimes birds and small mammals.
Their predatory behavior could drastically disrupt food webs and ecological conditions, thus forever changing native aquatic systems by modifying the array of native species.
LO 2.28 The student is able to use representations or models to analyze quantitatively and qualitatively the effects of disruptions to dynamic homeostasis in biological systems.
The Snakehead is an invasive species that disrupts a biological system by altering the aquatic food webs.
A Native Fish Resembling Snakeheads: the Bowfin
Snakeheads, especially the two large species Channa marulius and C. maruloides (a southeast Asian species not yet found in North America) bear a superficial resemblence to the native North American Bowfin or mudfish, Amia calva.
The Bowfin is a hardy species that lives in swampy, vegetated, and stagnant waters and, like the snakehead, can breathe oxygen directly from the air. It feeds voraciously on fish, crayfish, vegetation, and insects. Through evolutionary convergence these unrelated fish resemble each other and occupy a similar niche. The Bowfin occurs in much of the Mississippi River drainage as well as Atlantic coast drainages north through the Chesapeake Bay basin. In addition, it is found in parts of the Great Lakes basin.
The presence of Northern Snakehead in North America is of great concern. It is a hardy, predaceous fish with few predators, can disperse widely, and is adapted to a wide range of temperatures and environmental conditions. Once established, the species would be virtually impossible to eradicate from the continent's fresh waters, and could adversely impact indigenous aquatic species.

56. 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.
From a study site adjacent to a control site,
Remove only the sea urchins
Remove only the limpets
Remove both sea urchins and limpets

57. 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.
From a study site adjacent to a control site,
Remove only the sea urchins
Remove only the limpets
Remove both sea urchins and limpets

58. Predator Removal
interpret each of the 4 lines on this graph.

59. Predator Removal
Removing both limpets and urchins or removing only urchins increased seaweed cover dramatically
This is a lesson in “isolating variables”. If anyone in your audience has goals of becoming a research scientist, physician, veterinarian, pathologist or forensic scientist, they need to practice this skill at every opportunity! Since both sea urchins and limpets are predators of the seaweed, removing both SHOULD have a dramatic + effect on seaweed growth compared to the control site. The next step is to examine the data isolating each variable.

60. Predator Removal
Almost no seaweed grew in areas where both urchins and limpets were present (red line) , OR
where only limpets were removed (blue line)
This is still a lesson in “isolating variables”. Removing only limpets had very little effect on increasing the amount of seaweed growth. Removing only limpets also let the sea urchins “chow down” on the seaweed, thus sea urchins have a MUCH GREATER effect than limpets in limiting seaweed distribution.

61. Relationship Between Temperature and Precipitation
LO 1.5
The student is able to connect evolutionary changes in a population over time to a change in the environment. Organisms are impacted by Abiotic Factors