Ch. 14 Interactions in Ecosystems

Transcription

1 Ch. 14 Interactions in Ecosystems 1

2 14.1 Habitat vs. Niche Habitat all biotic and abiotic factors where an organism lives WHERE a species lives 2

3 Ecological Niche All physical, chemical, and biological factors needed to: Stay alive Stay healthy Reproduce 3

4 Ecological Niche Can be described in terms of: Space utilization Food consumption Where it fits in the food web When it s active Temperature range Moisture requirements Mating requirements 4

5 Ecological Niche Role of particular species in ecosystem Its job The impact of its presence How an organism lives within its habitat NOT WHERE it lives 5

6 Resources to Survive Organisms must have: Food Shelter Water Birds of Paradise 5 min 6

7 Competition When two species must use same resources Food Living space Light Water Mates 7

8 Competitive Exclusion If two species are competing, the one that uses the resource(s) most efficiently will eventually eliminate the other One eliminated: New niche Become extinct 8

9 Niche Partitioning When a niche is divided Animals stay in only part of area even though they could live in any of it Avoids competition Ex: Bees and butterflies Both use flowers for food 9

10 Warbler Niche Partitioning 10

11 Ecological Equivalents Species that occupy similar niches but live in different areas Ex: Poison dart frog of South America and mantella frog of Madagascar Both: Bright, poisonous, live in similar habitats, eat similar insects DON T compete bc live in different areas of world 11

12 14.2 Community Interactions Competition Two species use same resources Predation one organism captures and feeds on another 12

13 Predator Prey Relationships Predator Organism that kills for food Prey Organism eaten 13

14 Competition 1) interspecific between 2 different species Ex: dandelions and grass 2) intraspecific within same species Ex: male birds 14

15 Symbiotic Relationships Symbiosis Different organisms living in close, long term relationship Types: Mutualism Commensalism Parasitism 15

16 Mutualism Both benefit Animal partnerships 4:20 16

17 Mutualism Ex: Ants and aphids Aphids suck fluid (honeydew) from plants Ants milk aphids; use honeydew as food Ants protect aphids 17

18 Commensalism One benefits, one unaffected Ex: Demodicids (mites) in eyelashes The Unknown Micro World 7 min 18

19 Commensalism Ex: Sea anemone Tentacles are poisonous Clown fish Protection; not bothered by poison 19

20 Parasitism One benefits = parasite One loses = host 20

21 Parasitism Most parasites do not kill their host Why not? Ex: wasp and caterpillar 21

22 Parasitism 2 types: Ectoparasite live on outside of host Ex: leeches, ticks, fleas Endoparasite lives on inside of host Ex: tapeworms, hookworms 22

23 14.3 Population Density Number of individuals in a defined space = # of individuals area (units 2 ) 23

24 Population Dispersion How individuals within a population are spread in an area 3 types: 1) clumped 2) uniform 3) random 24

25 1) Clumped Live close together Helps with: Mating Protection Food resources 25

26 2) Uniform Live at specific distances Due to competition: for territory Between species 26

27 3) Random Spread out with no clear pattern 27

28 Survivorship Curve Diagram that shows # of survivors of a group over time Ex: All the people born in 1920 Track until all die Plot data 3 Types: I II III 28

29 Type I Large mammals Humans Most survive until old age Need parental care 29

30 Type II All ages survive at ~ equal rate Ex: Birds Small mammals Some reptiles 30

31 Type III High birth rate and infant mortality rate Ex: Few survive until adulthood Invertebrates Fish Amphibians Plants 31

32 14.4 Demography Statistical study of populations Demographer Studies composition of a population Predicts changes in size 32

33 Demography 33

34 Demographics 34

35 Population Growth Rate Growth More born than die Decline More die or leave than born 35

36 Population Changes Immigration individuals move into an area Emigration individuals move out of an area Birth Death 36

37 Population Growth Curves Graph Change in population over time Y-axis = Population X-axis = Time (generations) 37

38 Exponential Growth Population increases dramatically in short time Resembles J shape Ex: rabbits in Australia 24 brought for sport hunting Now over 200 million Australian Rabbits 2:46 38

39 Carrying Capacity Max population an environment can support Cannot grow unchecked Limited by: Predators Disease Resources Population density 39

40 Logistic Growth Population held in check: Resembles S shape Carrying capacity represented Takes into account declining resources How most populations grow 40

41 Logistic Growth Carrying Capacity: If Below rate is rapid If Near rate slows If above rate falls 41

42 Population Crash Dramatic decline in short time Ex. of Causes: Food Disease War Ex: Reindeer on St. Matthew Island, AK 42

43 Limiting Factor Factor w greatest effect of keeping population down 2 types: Densitydependent Densityindependent 43

44 Invasive Species Do not belong Not native Exotics Have not developed relationships over long periods of time Problems! 44

45 Density-dependent Affected by # of individuals in area Ex: More crowded can lead to more problems Competition Predation Parasitism Disease 45

46 Densityindependent Parts that limit population growth regardless of population density Ex: Unusual weather Natural disasters Human activities 46

47 14.5 Succession Sequence of biotic changes Regenerate damaged community Creates new community in a previously uninhabited area Ex: Hawaii Regular progression of species replacement 47

48 Succession Forms new habitats Occurs after: Forest fires Volcano eruptions Glacier recedes 48

49 Primary Succession Primary succession Occurs in habitat previously uninhabited 49

50 Primary Succession Pioneer Species First organisms to live in a previously uninhabited area Colonizers Small fast growing plants Change the soil over time Ex: lichens and some mosses 50

51 Secondary Succession Reestablishment of a damaged ecosystem where soil was left intact Ex: abandoned field or forest clearing Always occurring 51

52 Example of Succession Glacier Bay, Alaska Primary succession Receding glacier left piles of rocks and gravel Pioneer species Lichens Moss Fireweed Willows 52

53 Glacier Bay Succession 10 years later Dead leaves of plants enriched soil Alders enter by seed Nitrogen fixing nodules add nitrogen to the soil 53

54 Glacier Bay Succession 30 years later: Willows Alders Cottonwoods Thickets of trees and shrubs Kill smaller pioneer species 54

55 Glacier Bay Succession 80 years later: Sitka spruce invade Use nitrogen Form dense forest Alder dies out (little sunlight) Next, Hemlock enter Shade tolerant Stable community formed 55