Intro to Ecology

1. Intro to Ecology

2. Common Themes in Biology Organization Response to environment Homeostasis – maintaining an internal level of stability even though external environment is changing Energy use Growth and Development Reproduction Changes through time

3. What is Ecology?? The study of interactions that take place between organisms and their environment. It explains how living organisms affect each other and the world they live in.

4. Habitat & Niche • Habitat is the place an organism lives • Niche is an organism’s total way of life

5. The Nonliving Environment • Abiotic factors - the nonliving parts of an organism’s environment. • Examples: • air currents, • Temperature, • moisture, • light, • Soil nutrients

6. The Living Environment Biotic factors - all the living components of an environment. All organisms are affected by both biotic and abiotic factors in their niches

7. Abiotic or Biotic?

8. Abiotic or Biotic?

9. Abiotic or Biotic?

10. Abiotic or Biotic?

11. Levels of Organization • Ecologists have organized the interactions an organism takes part in into different levels according to complexity.

12. 1st Level of Organization Organism: An individual living thing

13. 2nd Level of Organization Population: A group of the same species, which live in the same area

14. 3rd Level of Organization Biological Community: All the populations of different species that live in the same place at the same time.

15. 4th Level of Organization Ecosystem: Populations of organisms that interact with each other in a given area ALONG with the abiotic components of that area.

16. 5th Level of Organization • Biosphere: The portion of Earth that supports life. • It is about 20 km (13 mi) wide from deepest parts of ocean to 8-10 km above the surface • The Earth is 600 times as thick as the biosphere • If Earth was an apple, the biosphere would be the skin

17. Levels of Organization • So, from smallest to biggest: • Organism • Population • Community • Ecosystem • Biosphere

18. Water Cycle Important words to know Transpiration- when plants lose water (usually through stomata) Evaporation- water turns from liquid to gas Condensation – Water vapor condenses into clouds Precipitation – any sort of water falling from the sky (rain, sleet , snow) Runoff- when water runs across land

20. How are humans overloading the carbon cycle? • Carbon dioxide is a greenhouse gas and traps heat in the atmosphere. • Without it and other greenhouse gases, Earth would be a frozen world. • But humans have burned so much fuel that there is about 30% more carbon dioxide in the air today than there was about 150 years ago. The atmosphere has not held this much carbon for at least 420,000 years according to data from ice cores.

21. Carbon Cycle • The way that carbon is fixed into an environment – PHOTOSYNTHESIS • From the plants, animals receive carbon (up the food chain – discussed later) • Carbon is released into the atmosphere • Burning of fossil fuels/forest fires/etc • Decomposing matter • Respiration (breathing out CO2)

22. The Carbon Cycle

23. Nitrogen Cycle • Even though the air is mostly N2 gas, many organisms cannot use it. • To be used by organisms the nitrogen must be fixed – nitrogen fixation • Without nitrogen, no protein or nucleic acids!

24. Nitrogen Cycle • Ways in which nitrogen is “fixed” into an ecosystem: • Lightning strikes • Soil microbes (bacteria that convert nitrogen to a usable form) • Nodules on the roots of legumes (symbiotic relationship) • From the plants, animals receive nitrogen (up the food chain – discussed later) • Ways in which nitrogen is released into atmosphere: • Decomposing matter • Industrial complexes

25. Nitrogen Cycle

26. Population Ecology

27. Population Ecology • Population Ecologists study many factors dealing with population, the three most important are… • Population density • Growth rate • Carrying capacity

28. Population Density • Population density measures how crowded a population is • The population density of the US is about 30 people per square kilometer (0.6 mi2) • In Japan it is 337 people/km2 • (Data from 2003)

29. Growth Rate • Growth rate- the amount by which a population size changes over a given time • In order for a population to grow, the birth rate (number of individuals born) must be greater than the death rate (number that die) • Population size constantly changes in any given population due to changes in growth rates

30. Growth Rate – Linear Model • Population grows by the same amount at regular intervals (week, month, year) producing a straight line when graphed • Ex: population grows by the same amount every month (2,4,6,8,10,12) • X axis is time • Y axis is population size

31. Growth Rate – Exponential Model • The number of individuals added to the population gets larger during each time interval or generation • Ex: population may grow at pattern such as (1,2,4,8,16,32,64 …) • When plotted on a graph the line looks like the letter “J” • X axis is time • Y axis is population size

32. Can populations grow infinitely? NOOO!! • Every ecosystem has a Carrying capacity • This is the maximum number of organisms that can be supported in a given habitat. • The carrying capacity of a habitat is based on limiting factors

33. Growth Rate – Carrying Capacity • Used to represent carrying capacity • Typically happens when organisms are introduced to a new ecosystem with few predators • At first population will grow slowly then rapidly • Eventually population will reach the carry capacity and then remain stable at that level • X axis is time • Y axis is population size

34. Limiting factors for carrying capacity • Density-Dependent • Depends on population size • Increases in food competition, disease, predator/prey • Decrease in living space and available water • Density-Independent • Affects the same percentage of a population regardless of its size • Natural disasters such as hurricanes, fires, earthquakes, volcanoes or tsunami destroy a habitat • Human intervention as burning of fossil fuels increases greenhouse gases linked to global warming, deforestation

35. Increase in Human Population • Agricultural Revolution - Major period of population growth began when humans started to cultivate crops and domesticate animals • Industrial Revolution – Improved food production and distribution • Health Care – germ theory lead to improved hygiene, better waste removal and water treatment

36. Decrease in Human Population • Plague – disease that greatly reduces the size of population (Black Plague in 1300’s reduced the population in England by 50%) • Famine –a severe food shortage causing starvation and death (Potato Famine of 1840’s/China 1870-1890) • War – death by combat, disease, cut off from food supply (Germany 1618-1648/WWI/WWII)

37. Human Population Over Time

38. Community Ecology • Looks at the interactions of populations within an ecosystem

39. Species Interactions In Communities

40. There are 5 major types of Interactions 1.Predator-Prey 2. Competition 3. Parasitism 4. Mutualism 5. Commensalism

41. Predator-Prey • The prey is the organism that is eaten • The predator is the organism that does the eating • Examples: • Lions eating Zebras • Snakes eating Mice • Birds eating insects

42. Predator and Prey Populations rise and fall with each other

43. Competition • Competition occurs when two or more organisms attempt to use the same limited resource. • A limited resource is any resource that may run out. • Examples: • Hyenas fight with lions over the same animals • Two cacti that are side by side compete for water

44. Symbiosis • Close association between two or more organisms of different species living together • 3 types • Parasitism • Mutualism • Commensalism

45. Parasitism • Parasitism is the relationship between a parasite and a host. • A Parasite is an organism that lives in or on another organism and feeds on it without immediately killing it. • Examples: ticks, fleas, blood-sucking leaches, and mistletoe • The organism that the parasite feeds on is called the Host • The host is harmed in parasitism.

46. Mutualism • Mutualism is a cooperative partnership between two species in which both species benefit. • An example is the bacteria in your intestines and you. • Billions of bacteria live in your intestines. • They help break down food you would otherwise not be able to digest. • They also produce beneficial substances, such as Vitamin K for you. • In return, you give them a warm, dark, food-rich environment.

47. Commensalism • Commensalism is a relationship in which one species benefits from another species and the other is neither harmed nor helped • This is the rarest and strangest type of species interaction • Example: Remoras and Sharks • The remoras attach to the sharks and feed on scraps left over from the sharks meals. • The shark is neither harmed nor helped by this relationship

48. Benefit vs. Harm Relationship Organism #1 Organism #2 Commensalism + 0 Mutualism + + Parasitism + - Predator Prey + - Competition - -

49. Great White Shark eating Seal- PREDATION

50. Lion eating Zebra- PREDATION