Population Basics
Population Ecology Study of populations in relation to the environment Purpose: Increase population size= endangered species Decrease population size = pests, invasive species Maintain population size= wildlife management
Life takes place in populations.. Population Group of individuals of the same species in the same area at the same time. Rely on the same resources Interact and interbreed
Factors affecting population size Abiotic factors Sunlight & temperature Precipitation/water Soil/nutrients Biotic factors Other living organisms prey (feed) competitors Predators, parasites, disease Intrinsic Factors - Adaptations
Characterizing a Population Population range Pattern of spacing (density) size of population
Estimating Populations
Estimating population size Mark and Recapture method 1. Random sample of individuals marked and tagged 2. Tagged individuals released and remix 3. Second sample captured N = sn x N= estimated population size s= individuals tagged in first capture n= total individuals in second capture x= marked individuals in second capture
Estimating population size Assumes that Marked and unmarked individuals have the same chance of being captured Tagged individuals given time to remix No population changes between first and second capture
Estimating population size Example: A pest control technician captures and applies ear tags to 23 brown rats, which he then releases. A week later he traps 29 brown rats, 11 of which have ear tags. What is the estimate of the total population of brown rats? N = sn x N= estimated population size s= individuals tagged in first capture n= total individuals in second capture x= marked individuals in second capture
Estimating population size Example: You want to estimate the population of box turtles in woods behind your house. The first day you capture 24 turtles, mark, and release them. A week later, you catch 60 turtles with 45 of them being unmarked. What can you estimate the population to be? N = sn x N= estimated population size s= individuals tagged in first capture n= total individuals in second capture x= marked individuals in second capture
Population Structures
Population Density Number of individuals per unit area or volume Not static- Always changing due to : Immigration Emigration Births Deaths Calculation
Patterns of Dispersal Clumped Individuals clustered in patches Most common Advantages?
Patterns of Dispersal Uniform Evenly spaced Result of direct interactions between individuals in population Sometimes due to social behavior/ territoriality
Patterns of Dispersal Random Unpredictable Occurs due to absence of strong attraction or repulsion Rare
Graphical Representations
Survivorship Curves Follow cohort group over period of time Plot how many individuals are still alive What would you expect this to look for humans?
Survivorship Curves
Reproductive Strategies K-selected Late reproduction Few offspring Invest a lot in raising offspring Ex. humans, primate, coconut tree r-selected Early reproduction Many offspring Little parental care Ex. insects, many plants
Exponential Population Growth Intrinsic rate of increase Members of population reproduce at maximum rate Must have abundant resources Ex. bacteria, introduced species
Larger r max, faster growth
Exponential Growth
Logistic Population Growth Population s growth rate slows as it reaches carrying capacity Rate decreases as population increases Loosely fits more populations As N approaches K, growth slows then stops
Logistic Growth Affected by limiting factors: Density dependent= food, water, shelter, disease, predators, etc. Density independent= sunlight, natural disasters, temperature **Carrying Capacity** is determined
Age Structure Diagram
REVIEW https://www.youtube.com/watch? v=rbosqmbqbqk
Test Review- Animal Behavior Practice Questions
1. Which of the following might affect the foraging behavior of an animal in the context of optimal foraging? I. Risk of predation II. prey size III. prey defenses IV. prey density A. I, II, III. IV B. only I, II, and III C. only I and III D. only II and IV
2. What type of communicative signal is long-lasting and works at night? A. electrical B. olfactory C. auditory D. visual
3. Upon observing a golden eagle overhead, a sentry prairie dog gives a warning call to other foraging members of the prairie dog community. A. agonistic behavior B. innate behavior C. imprinting D. altruistic behavior
4. A mother goose can recognize its own kid by smell A. agonistic behavior B. innate behavior C. imprinting D. altruistic behavior
5. Which of the following statements about evolution is correct? A. An animal may show behavior that minimizes reproductive fitness B. Natural selection will favor behavior that enhances survival and reproduction C.If a behavior is less than optimal, it will eventually become optimal through natural selection D. Innate behaviors cannot be altered by natural selection
6. Animals that help other animals of the same species A. are always male B. have excess energy reserves C. are usually related to other animals helped D. are bigger and stronger than the other animals
7. A cage containing male mosquitoes has a small earphones placed on top, through which the sound of a female mosquito is played. All the males immediately fly to the earphone and go through all of the steps of copulation. What is the best explanation for this behavior? A. The reproductive drive is so strong that when males are deprived of females, they will attempt to mate with anything that has even the slightly female characteristic. B. Copulation is a fixed action pattern, and the female flight sound is a sign stimulus that initiates it. C. Through classical conditioning, the male mosquitoes have associated the inappropriate stimulus from the earphone with the normal response of copulation. D. The sound from the earphone irritates the male mosquitoes, causing them to attempt to sting it.
8. Which of the following examples best describes a behavioral pattern that results rom a proximate cause? A. A female bird lays eggs because the amount of daylight is decreasing slightly each day, altering estrogen production. B. A cat kills a mouse to obtain nutrition C. A male sheep fights with another male because it helps improve its social position D. A goose squat and freezes motionless to escape a predator
9. Which of the following is true of innate behaviors? Innate behaviors A. are only weakly influences by genes B. occur in invertebrates and some vertebrates, but not mammals C. are expressed in most individuals in a population D. are limited to invertebrate animals
Test Review- Population Dynamics Practice Questions
10. In the figure, which of the following curves most applies to humans in developed countries? A. Type I B. Type II C. Type III
11. In the figure, which of the following curves most applies most to plant species? A. Type I B. Type II C. Type III
12. To measure the population of lake trout, 400 individuals trout were netted, marked, and released. The next week, 200 trout were netted again, 150 lacking fin clips. Estimate the population size. A. 1,600 B. 80,000 C. 533 D. 406
13. An ecologist recorded twelve white-tailed deer per square kilometer in one woodlot and twenty square kilometer in another woodlot. What was the ecologist comparing? A. dispersion B. range C. density D. carrying capacity
14. Uniform spacing of the creosote bush is often associated with A. competitive interaction between individuals of the same population B. the concentration of nutrients with the population s range C. the random distribution of seeds D. patterns of high humidity
15. Which statements about K are correct? I. K varies among populations II. K varies in space III. K varies in time IV. K is constant for any given species A. I, II, III C. I and III B. II, III, IV D. II and IV
16. Which of the following causes populations to shift most quickly from an exponential to a logistic population growth? A. Competition for resources B. Decreased birth rate C. Removal of predators D. Favorable climatic conditions
17. In which of the following situation would you expect to find the largest number of K-selected individuals? A. A recently abandoned agricultural field in Ohio (Ew) B. South Florida after a hurricane C.an old-growth forest D. A shifting sand dune community of south Lake Michigan
18. Why does the 2009 US population continue to grow even though the US has essentially established a zero population growth? A. Immigration B. The 2007-2009 economic recession C. Emigration D. Baby boomer reproduction
19. Which of the following graphs illustrates the growth over several seasons of a population of snowshoe hares that were introduced to an appropriate habitat also inhabited by predators in Northern Canada?