biol 101 chp 54: community ecology

Community Ecology

BIOL 101: General Biology I

Chapter 54

Rob SwatskiAsst. Prof. Biology

HACC - York1

2 What is a “Community”?

3

InterspecificInteractions

Predation & Herbivory

Competition

Symbiosis

4

5

InterspecificCompetition

-/-interaction

Competitive Exclusion Principle

Resource partitioning

Ecological niche

A. ricordii

A. aliniger

A. distichus

A. insolitus

A. christophei

A. cybotes

A. etheridgei

Resource Partitioning6

7

Ecological Niche

Realized Niche

Fundamental Niche

Ocean

Chthamalus

Balanus

EXPERIMENT

High tide

Low tide

Chthamalusrealized niche

Balanusrealized niche

8

RESULTS

High tide

Chthamalusfundamental niche

Low tideOcean

9

10

Predation &

Herbivory

+/-interaction

Feeding adaptations of predators

Defensive adaptations

of prey

Cryptic Coloration (Camouflage)

11

12

13

Which is Which?

14

15

16

17

18

19

Aposematic (Warning) Coloration

20

21

22

23

24

25

26

27

28

29

30

31

32Aposematic or Cryptic Coloration?

33

Mimicry

Batesian Mullerian

34

Batesian Mimicry

Syrphid fly

Honey bee

35

36

37

38

39

40

Mullerian Mimicry

Viceroy

41Monarch

42

42

43

Symbiosis

Mutualism

Commensalism

Parasitism

44

Parasitism

Parasite-host interaction (+/-)

Ectoparasite

Endoparasite

45Human Head Louse

Ectoparasite

46Tick

47

Ectoparasite

Tapeworm scolex

48

Mutualism

+/+ interaction

Obligate

Facultative

Ants & Acacia tree

49

50

51

52Ants & Aphids

53

54

Commensalism

+/0 interaction

55

56

Species Diversity

Species richness

Relative abundance

Community 1A: 25% B: 25% C: 25% D: 25%

Community 2A: 80% B: 5% C: 5% D: 10%

A B C D

Two communities can have the same species richness, but have a different relative abundance 57

Soil pH

Shan

no

n d

ive

rsit

y (H

)

3.6

RESULTS

3.4

3.2

3.0

2.8

2.6

2.4

2.23 4 5 6 7 8 9

Microbial Species

Richness

Molecular evidence

58

Food Chains

Carnivore

Carnivore

Carnivore

Herbivore

Plant

Terrestrial

Quaternaryconsumers

Tertiaryconsumers

Secondaryconsumers

Primaryconsumers

Primaryproducers

Phytoplankton

Zooplankton

Carnivore

Carnivore

Carnivore

Marine 59

Humans

Smallertoothedwhales

Baleenwhales

Spermwhales

Elephantseals

Leopardseals

Crab-eaterseals

Birds Fishes Squids

Carnivorousplankton

CopepodsEuphausids(krill)

Phyto-plankton

Food Web

60

Sea nettle

Fish larvae

Juvenile striped bass

Fish eggs Zooplankton 61

62

Limits on Food Chain Length

Most are 3-4 links

Energetic Hypothesis

Dynamic Stability

Hypothesis

63

Dominant Species

Are either the most abundant

or…

have the highest biomass

How?

64

Invasive Species

65Purple Loosestrife

66

Keystone Species

Is Pisasterochraceus a

keystone predator?

67

With Pisaster (control)

Without Pisaster (experimental)

Nu

mb

er

of

spe

cie

sp

rese

nt

Year

20

15

10

5

01963 ’64 ’65 ’66 ’67 ’68 ’69 ’70 ’71 ’72 ’73

RESULTS

68

(a) Sea otter abundanceO

tte

r n

um

be

r(%

max

. co

un

t)

100

80

60

40

20

0

400

300

200

100

0

(b) Sea urchin biomass

Gra

ms

pe

r0

.25

m2

108

642

01972

Nu

mb

er

pe

r0

.25

m2

1985 1997Year

(c) Total kelp densityFood chain

1989 1993

69

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