Populations and Community Ecology Chapter 19 and 20 Populations and Community Ecology

Why is it important to study Populations? Let’s consider the human specie population… Currently: about 6.1 billion Projected growth: 9.3 billion by 2050 Have other species increased or decreased? Can human population increase faster than food production? 9/19/2018 Add a footer

What is a population? all the fish in a pond All the birds in NYC A group of organisms that belong to the same species and live in a particular place at the same time. (Should be isolated and not interact with others) Question: Which of the following is a population? all the fish in a pond All the birds in NYC All the members of a family of humans All the fish of the same species in a lake. 9/19/2018 Add a footer

Dispersion (Distribution) Population Size Number of individuals that population contains Population Density the average number of individuals in a population per unit of area Dispersion (Distribution) describes how the individuals are distributed 9/19/2018 Add a footer

1. Dispersion Spatial distribution of individuals Clumped Uniform Random 9/19/2018 Add a footer

Continuation on Dispersion Clumped Allows organisms to hunt or defend themselves more efficiently Uniform Maximize the distance from all of the neighbors Random Individuals do not interact strongly. Most populations show clumping or uniformity Benefits to each?

2. Population Equilibrium Affected by: birth rate and death rate. When birth rate equals the death rate, the population remains at a constant level. = 9/19/2018 Add a footer

3. Birth Rate 4. Death Rate (Natality) Number of live births (Mortality) Number of deaths 9/19/2018 Add a footer

5. Growth Rate The amount by which a population changes Rate of increase is represented by: Birth rate – death rate = Growth Rate 9/19/2018 Add a footer

What affects growth rate? 6. Factors that affect GROWTH RATE 1. Immigration 2. Emigration Nasality 3. Birth Rate 4. Death Rate Immigration (+) Emigration (-) Mortality Growth Rate 9/19/2018 Add a footer

8. Emigration 7. Immigration vs. Movement of individuals into a population Movement of individuals out of a population 9/19/2018 Add a footer

How do population grow????? 9. Exponential Growth (J) 10. Logistic Growth (S) The exponential form is used when populations reproduce continually Actually, the human population has shown faster-than-exponential growth, but is now exhibiting a gradual slowing of the growth rate Population will exhibit an initial exponential phase followed by slowed growth. 9/19/2018 Add a footer

What causes growth to slow down???? 11. Carrying Capacity (k) The maximum population size that can be supported by the available resources There can only be as many organisms as the environmental resources can support!!!!! Food supply Disease Predation Buildup of toxic waste 9/19/2018 Add a footer

Chapter 20 Community Ecology 9/19/2018 Add a footer

This chapter focuses on the five major types of interactions among species 1.Predation 2. Competition 3. Parasitism 4.Mutualism 5. Commensalism

12. Predation An individual of one species, called the predator, consumes a prey. 9/19/2018 Add a footer

13. Adaptations in animals vs. plants Animal avoid being eaten by: Fleeing Chemical defenses Mimicry (Harmless king snake mimics a venomous snake) Plants avoid being eaten by: Thorns Spines Tough leaves Secondary compounds 9/19/2018 Add a footer

14. Competition Type of interaction in which two or more species use the same resource. 9/19/2018 Add a footer

15. Symbiosis Any of the several living arrangements between two different species. Includes: Parasitism Mutualism Commensalism 9/19/2018 Add a footer

Examples of Symbiosis 16. Parasitism 17. Mutualism 18. Commensalism Host is harmed while parasite benefits Doesn’t lead to immediate death 17. Mutualism Both species will result in a benefit 18. Commensalism One specie is affected while the other isn’t affected 9/19/2018 Add a footer

Use the following adjectives to describe each specie: “benefited” “harmed” or “unaffected” Interaction Species A Specie B Example Predation   Rattlesnake hunt and feed on mice Competition Barnacles compete for space in intertidal zones Parasitism Tapeworms are endoparasites in humans Mutualism Bees pollinate plants Commensalism A bird nests in a tree 9/19/2018 Add a footer

19. Latitude and Specie Richness The closer a community is to the equator, the more species it will contain. Due to more stable climate Due to tropical habitats weren’t disturbed in the last Ice Age as the habitats closer to the poles. Specie Richness is the number of species in a community. 9/19/2018 Add a footer

Disturbances are events that change communities One of the most important characteristics of a community is how it responds to disturbances. Change communities by removing/destroying organisms; altering resources. 9/19/2018 Add a footer

20. Ecological Succession The gradual, regrowth of a community of species. Lichens will colonize rock and secrete acids that break down the rock and start the soil-production process. 9/19/2018 Add a footer

There are 2 types of Succession….. 21. Primary Succession 22. Secondary Succession Development of a community that has not supported life previously Very slow!!!!!! Replacement of species that follows disruption of an existing community 9/19/2018 Add a footer

23. Pioneer Specie First species that predominate early in succession When lichens die, they provide some organic matter that also contributes to soil. 9/19/2018 Add a footer

24. Climax Community Series of stages until a community proceeds to its stable endpoint 9/19/2018 Add a footer