Chapter 14

1. Chapter 14 Interactions in Ecosystems

2. Section 14.1 Habitat and Niche (page 428) • What is a habitat? • Habitat- where an organism lives • Include biotic and abiotic factors • Give some examples:

3. Each species interacts with its environment in a different way. • An ecological niche is composed of all of the physical, chemical, and biological factors that a species needs to survive, stay healthy, and reproduce; its role. • Includes: • Food: what kind, how it is obtained, etc… • Abiotic conditions: temperature, amount of water needed, etc… • Behavior: when it is active during the day, where and when it reproduces, etc… • You can think of a habitat as where a species lives and a niche is how it lives within its habitat.

4. Niche Examples • Savannah grasses are food for antelope and places of camouflage for lions; two different roles or niches • The red fox is a predator which feeds on the small mammals, amphibians, insects, and fruits found in this habitat. They are active at night and provide blood for blackflies and mosquitoes, and are hosts to numerous diseases. The scraps, or carrion, left behind after a fox's meal provide food for many small scavengers and decomposers. • Red foxes can be found around forest edges, meadows and the banks of rivers.

5. Question • Can two different species occupy the same exact niche? • What happens when two species occupy similar niches?

6. Section 14.2 Community Interactions (page 431) • Competition—two organisms fight for the same resources • Interspecific competition—between two different species • Intraspecific competition—between members of the same species

7. Predation (+, -)—one organism feeds on another organism • Can also be herbivores eating producers, this is called herbivory • Plants use various defenses against herbivory • What are they?

8. Symbiosis • Symbiosis—“living together”; relationships between different species living closely together • Mutualism—both species benefit (+/+) • Commensalism—one member benefits, the other is not helped nor harmed (+/0) • Parasitism—one organism lives off the other organism while harming it (+/-) • Ectoparasite—lives outside the host • Endoparasite—lives inside the host

9. What kind of symbiosis is this? • (Hint: Bromeliads live in the tops of the trees in rain forest without harming trees) • Commensalism

10. What kind of symbiosis is this? • Parasitism-What kind?

11. What kind of symbiosis are these?

12. What kind of symbiosis is this? Mutualism

13. What kind of symbiosis is this? • Parasitism-What kind?

14. What kind of symbiosis is this? • Mutualism

15. What kind of symbiosis is this? • Commensalism

16. Section 14.3 Population Density and Distribution on page 436 • Three important features of population: • 1. Population size—the number of individuals in a population • Small populations are more likely to become extinct according to research. • Inbreeding is also a common problem in small populations, reducing the population’s fitness.

17. 2. Population density—the number of individuals that live in a given area • *Reproduction is difficult if few individuals are spread widely apart # of individuals = population density Area (units2) • When population densities change over time, scientists can examine if there are environmental factors causing the change or just normal variation of life history.

18. 3. Dispersion—the way individuals of a population are arranged in an area • Three patterns of dispersion: • Random—ex. Solitary animals such as sloths • Even or Uniform—occur at regular intervals—ex. Nesting sites of gannet on page 437 • Clumped—individuals are bunched together in clusters—ex. Schools of fish

20. Survivorship curves • Survivorship curves illustrate how offspring survival from birth to death fits in with the survival strategies of a particular species. A survivorship curve is a diagram that shows the number of surviving members over time from a measured set of births • Gives information about the life history of a species

21. 3 Basic Patterns of Survivorship Curves • Type I—low level of infant mortality and a population that will mostly survive to old age • common in large mammals (and humans); characterized by infant care to ensure infant survival • Type II—survivorship rate is roughly equal at all ages of an organism’s life • common in birds, small mammals, and some reptiles; susceptible to predation and disease • Type III—very high birth rate but very high infant mortality rate, few move on to adulthood • invertebrates, fish, amphibians, and plants; many offspring die from predation

22. http://www.bioinquiry.vt.edu/bioinquiry/cheetah/cheetahpaid/cheetahhtmls/popsurvivor.htmlhttp://www.bioinquiry.vt.edu/bioinquiry/cheetah/cheetahpaid/cheetahhtmls/popsurvivor.html

23. Section 14.4 Population Growth Patterns on page 440 • Population sizes tend to fluctuate based on the availability of resources. • Four factors that affect the size of a population: • Immigration—movement of individuals into a population from another population • Births—increase the number of individuals in a population • Emigration—movement of individuals out of a population and into another population • Deaths—decrease the number of individuals in a population

24. 2 Types of Population Growth • Exponential Growth Curve(J-shaped curve)—a curve in which the rate of population growth stays the same, as a result the population size increases steadily • Resources (food and space) are abundant • J-curve is a population that will grow if all individuals survive and reproduce at maximum capacity with no limiting factors

25. Two phases: • Lag – little or no increase • Exponential – very rapid increase - # of individuals doubles in time intervals

26. 2 Types of Population Growth • Logistic Model(S curve) –a population model where exponential growth is limited by depleting resources causing a population to reach carrying capacity; relative stability that occurs after Lag and Exponential Phase • Carrying capacity—the maximum number of individuals an environment can support; where birth rate equals the death rate • In nature, carrying capacity can change when the environment changes • However, populations do not go unchecked and their growth is limited by predators, disease, and availability of resources.

29. Two types of limiting factors: • Density-dependent limiting factor—limited resources whose rates of depletion depend on the density of the population using them • Ex. Competition, predation, parasitism and disease • Density-independent factor—environmental conditions that limit population growth regardless of population size • Ex. Weather, natural disasters, human activity

30. Industrial Revolution begins Agriculture begins Plowing and irrigation • When carrying capacity suddenly drops, the population experiences a crash. A population crash is a dramatic decline in the size of a population over a short period of time. • When did this happen in human history? Bubonic Plague

31. R-strategists versus K-strategists(not it textbook) R-strategists • Ex: Bacteria, Cockroaches, mosquitoes, most insects, some plants • Grow exponentially when environmental conditions allow them to reproduce • Temporarily large populations • Short life span • Reproduce early in life • Produce many offspring during each time of reproduction • Small offspring with little or no parental care • When environmental conditions worsen, population size drops drastically • What type of survivorship curve is this? • Type III

32. K-strategists • Ex. Gorillas, whales, humans, elephants, Redwood trees, tigers • Populations grow slowly and population density is usually near the carrying capacity of the environment • Long life span • Few young with a slow maturing process • Reproduction late in life • Parents often provide extensive care for their young • Many endangered species are these • What survivorship curve is this? • Type I

33. Industrial Revolution begins Agriculture begins Bubonic plague Plowing and irrigation Let’s talk about Human Population

34. World Population Trends • In 1804, world population reached 1 billion • 1927: 2 billion (123 years later) • 1960: 3 billion (33 years) • 1974: 4 billion (13 years) • 1987: 5 billion (12 years) • 1999: 6 billion (12 years)

35. What factors do you think helped influence human population growth? • A variety of factors influence human population growth rates including, but not limited to, these: • Health care • Customs (value placed or large or small family) • Disease • Women’s roles • Government • Education • Economic stability • Religion • Malnutrition • Pollution

36. Concluding thoughts • Note that humans are unique in that we can control some of the factors that limit the growth of other populations. • We can also limit our own population growth.

37. Section 14.5 Ecological Succession What would happen to a lawn of grass if it were not cut for one year, fives years, or twenty years? • Ecologists can accurately predict the changes that take place. • Grasses will grow taller • Weeds start to grow in • Area appears meadow-like • Bushes start to grow, then trees • Animals enter the habitat • As the sunlight is diminishing, the grasses slowly start to disappear • About 30 years later, what do we have? • A forest! This is succession!

38. Succession • Succession is the sequence of biotic changes that regenerate a damaged community or create a community in a previously uninhabited area. • Occurs in stages • The species and different stages create conditions that are suitable for some organisms and unsuitable for others.

39. 2 Types of Succession • Primary succession (Figure 14.16)—succession that occurs in an uninhabited area • Examples • new lava or rock from a volcano, makes a new island or a new landscape • sand bar that arises from shifting sands in the ocean • exposure of rock surfaces by a land slide or glacial retreat • meteor makes a depression that fills with rainwater or fresh water from underground streams • sand dunes can be great for observing primary succession.

40. Rock surfaceLichens  Decomposers  Mosses  Ferns, shrubs  Pines  Hardwoods • Ex. Lichen on rock starts to die and make a foundation of soil for things like moss, then grass and ferns, bushes, trees, forest • Pioneer species—the first species in an area; usually lichen or moss which breakdown rock What is the pioneer species in the example above?

41. 2 Types of Succession • Secondary succession (Figure 14.17)—the sequence of community changes that takes place after a community is disrupted by natural disasters or human actions • Ex. Fire, natural disasters, human activity, etc… • Secondary succession is continually happening after small disturbances which kick start succession. Which occurs more often presently? Which type takes a longer amount of time to complete?

42. Pripyat Succession • City of Chernobyl Nuclear Power Plant disaster • On Saturday, 26 April 1986, an explosion and fire released large quantities of radioactive contamination into the atmosphere, which spread over much of Western USSR and Europe. • It is estimated that the radiation from the Chernobyl disaster was 100 times more powerful than the bombs dropped on Hiroshima and Nagasaki. Thirty-one people died shortly after the explosion, but thousands more will die from the long-term effects of radiation.

48. Mt. St. Helens SuccessionVolcanic eruption in 1980Pictures from 1988 and 2001