Ecology

1. Ecology Study of the interactions between organisms and the living and non-living components of their environment

2. Ecology is a broad science involving: • Collecting information about organisms and their environment • Observing and measuring interactions • Looking for patterns • Seeking to explain patterns • Interdependence is when an organism’s survival depends of interactions with their surroundings.

3. Ecosystem: all the organisms and nonliving environment in a particular place • Organism: one individual living thing • Habitat: the place where an organism lives • Species: a group of organisms that is able to reproduce together, share common genes and therefore resemble one another • Population: includes all the members of a species that live in one place at one time • Community: a group of interacting populations of different species

4. Energy Transfer • There is a hierarchy in the different levels of organization within organisms. From the biosphere to the ecosystem, communities to populations, to organisms. • Ecological models: a model that helps ecologists understand environmental interactions and predict changes. Used to help plan and evaluate solutions.

6. Deepwater Oil Rig Explosion

7. Energy Transfer • All organisms need energy to carry out life. • Autotroph: organisms that can capture sunlight and “make their own food”, also called producers. • Heterotroph: organism that relies on eating autotrophs or other heterotrophs, also called consumers – all animals! • Within the ecosystem – the energy comes from the sun and flows to the autotrophs, then heterotrophs consume it.

8. Energy transfer • Gross primary productivity is the rate at which the producers in an ecosystem capture the energy of sunlight: the organic molecules that they produce are referred to as biomass. • When ecologists study the accumulation of biomass they refer to it as the net primary productivity. • Think paychecks… gross vs. net

9. 4 Labels • Herbivores: eat producers ex) antelope eats grass • Carnivores: eat other consumers ex) lion eats the antelope • Omnivores: eat both producers and consumers ex) grizzly bear • Detrivores: (specifically called decomposers) garbage feeders, ex) vulture cleans up carcasses and aids in decomposition

10. Energy Flow • Energy flows from an organism into the one that consumes it. An organisms’strophic level indicates the position in a sequence of energy transfers. All producers are in the first trophic level, herbivores in the second, and predators in at least the third • Many ecosystems can only support 3 – 4 levels, marine can do much more. • Only about 10% of available energy is transferred to the next trophic level.

13. Populations • Species richness: how many species are in an area vs. species eveness: the abundance of each species • Richness is a count and will change with latitude in general, the closer to the equator you are the more species you’ll see

14. Species • Species-area effect is seen when you have a larger area, you’ll have more species than in a small area. • Species interactions and richness: some species are necessary to maintain the number of other species ex) less beef cows = less Ramseys

15. Populations • Disturbance is any event that could change an environment- earthquake, tornado, flood, volcano • Stability is the ability of a community to maintain constant conditions (similar to homeostasis in humans)

16. Succession • Gradual sequential re-growth of an area. • Primary sucession: development in an area previously not supporting life • Secondary sucession: sequential replacement of species that follows disruptions on existing communities

17. Succession • Pioneer species – small, quick growing fast to reproduce, predominate species ex) lichens and grasses on volcanic slopes • Primary succession occurs slowly- the soil is too poor to sustain much, it takes a while to build up organic material enough to support larger plants. The final stage of succession is called the climax community – very stable.

18. Patterns of Mortality • Survivorship curves show the probability of members in a population to survive to a certain age • Type I – likelihood of dying isn’t until late in life (humans) • Type II – likelihood of dying doesn’t change through life (bugs) • Type III – very likely chance of dying young (bears)

19. Measuring populations • Charles Darwin calculated that one pair of elephants could increase to a population of 19 million individuals within 750 years. • Why aren’t we overrun with elephants?

20. Immigration changes the population, it moves individuals into a population • Emigration is the movement of individuals out of a population. • Usually we discuss populations by the thousands, we present data “per capita”

21. Growth Models • Exponential Model: a steady growth rate and pattern of rapid increase. At this rate, more individuals are added than die off each year. When graphed, a J-shaped curve is shown. We see when the population is small, it grows slowly but as we get larger the faster it grows. 2 cows don’t reproduce as fast at 200.

22. Growth Models • Logistic Model: builds on the exponential model but accounts for limiting factors. • A limiting factor is anything that restrains the growth (money, space) • The carrying capacity of enviroment is how many individuals the area can support over a period of time. • This graph looks like an S; when population is small, birth rates are high and death is low. As it increases, birth rates go down and death rates increase

23. Population Regulation • 1. Limiting factors • Density-independent factors: weather, flood, fire, reduce the population regardless of the size by the same proportion • Density-dependent factors: resource limitations will determine the population size

24. Population Regulation • 2. Populations naturally fluctuate. Ex) Charles S. Elton (1900-1991) saw that the number of lynx and those of hares followed similar fluctuations. • Not what you think though- it wasn’t due to predation. On an island without lynx, the hares still fluctuated! • 3. Perils of small populations • Rapid growing human populations have caused extreme reductions in population of other species.

25. Perils, cont. • Only around 200 Siberian tigers remain in the wild because of hunting and destruction of habitat • California’s condor population in the 1980’s had dropped to only 9 individuals. Now there are 192 in the wild, 391 total live birds. They are the largest North American land bird.

26. Small populations • Small populations are extremely suceptible to extinction. Environmental factors can stress their environment (food, shelter) and either kill off all individuals of leave just a few to repopulate. (Shallow gene pool?) This leads to genetic vulnerability. The less variety, less likely to adapt for survival.

27. Human Population growth • 10-12,000 years ago the population was small, we had a hunter-gatherer lifestyle with high child mortality rates. • Agricultural revolution – 12,000 years ago led to domestication of animals and a steady food supply- population grew faster and mortality rates went down. • Theory says that industrial development causes socioeconomic changes, visible is 1-3 generations.

28. Biotic and Abiotic factors • Biotic factors are all the living aspects of an ecosystem • Abiotic factors are the physical and chemical characteristics fo the environment.

29. Abiotic Factors • Temperature • Humidity • pH • Salinity • Oxygen concentration • Amount of sunlight • Availability of nitrogen • Precipitation

30. Abiotic factors are not constant, not independent of biotic factors and they vary from time to time and place to place • Tolerance is how well something can survive at a given point.

32. A tolerance curve is a graph that shows how well an organism can function and survive outside its optimal range. This curve shows performance at a given variable like temperature on fish. • Acclimation – some organisms can adjust their tolerance to abiotic factors.

33. Control of Internal Conditions • Conformers are organisms that don’t regulate their internal conditions- they change as their external environment changes • Can you think of an example of this? • Regulators are organisms that use energy to control some of their internal conditions they can remain in optimal range over a wide • Can you think of an example of this?

34. Escape! • Some animals can escape temporarily from unfavorable conditions • Dormancy- a long term strategy of reduced activity • Migration – moving to a more favorable habitat • Do humans do this? How?

35. Niche: the specific role of life an organism plays within its environment • Generalists – species with a broad niche, can tolerate wide range of conditions & use a variety of resources • Specialists – species with narrow niches (Ex. Koala Bear with the eucalyptus tree leaves)

36. Competition • Interspecific: 2 or more species use the same resource, one wins • Ex) deer + quail + rabbits • Intraspecific: competing within one species (which is more intense?) • Intra- they all use the same resource in the same way so it comes down to who is genetically superior.

37. Predator + Prey • Natural Selection (survival of the fittest) favors the predator that can adapt and overcome • Prey use mimicry – looking like another species to prevent predation

38. Mimicry • Batesian – looking like a dangerous species • Mullerian – 2+ dangerous or distasteful (bees & wasps are black and yellow) • Plants also have developed defenses- physical and chemical (secondary compounds)

39. Predation and competition will decrease the niche size of a species • Fundamental niche is the range a species can potentially tolerate • Realized niche is the actual range

40. Symbiosis • Parasitism: one is harmed and one benefits • Mutualism: both get some benefit • Commensalism: one benefits while the other isn’t harmed or helped

41. Why do we have weather? • Latitudinal variation in sunlight intensity.

42. Why do we have weather? Seasonal variation in sunlight intensity.

43. Why do we have weather? Global air circulation and precipitation patterns.

44. Why do we have weather? • Global wind patterns. • Currents and other bodies of water.

45. Earth’s biomes

46. Tropical rainforest distribution: equatorial precipitation: very wet temperature: always warm characteristics: many plants & animals, thin soil

47. Savanna distribution: equatorial precipitation: seasonal, dry season/wet season temperature: always warm characteristics: fire-adapted, drought tolerant plants; herbivores; fertile soil

48. Desert distribution: 30°N & S latitude band precipitation: almost temperature: variable daily & seasonally, hot & cold characteristics: sparse vegetation & animals, cacti, succulents, drought tolerant, reptiles, insects, rodents, birds

49. Temperate Grassland distribution: mid-latitudes, mid-continents precipitation: seasonal, dry season/wet season temperature: cold winters/hot summers characteristics: prairie grasses, fire-adapted, drought tolerant plants; many herbivores; deep, fertile soil

50. Temperate Deciduous Forest distribution: mid-latitude, northern hemisphere precipitation: adequate, summer rains, winter snow temperature: moderate warm summer/cool winter characteristics: many mammals, insects, birds, etc.; deciduous trees; fertile soils