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Creative Community Ecology Ch 54 notes. I. Introductory Vocabulary  Community  group of populations in an area or habitat.

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Presentation on theme: "Creative Community Ecology Ch 54 notes. I. Introductory Vocabulary  Community  group of populations in an area or habitat."— Presentation transcript:

1 Creative Community Ecology Ch 54 notes

2 I. Introductory Vocabulary  Community  group of populations in an area or habitat

3 II. Interspecific Interactions  Relationships between the species of a community  Types include: Competition-/- Predation+/- Mutualism+/+ Commensalism+/0

4 A. Competition  Detrimental to both species  Organisms compete for available resources such as food, water, shelter, sunlight

5 1. Competitive exclusion principle  Two species so similar that they compete for the same limiting resource cannot coexist in the same place

6 2. Ecological niche  sum total of a species’ use of biotic and abiotic resources – how an organism fits into it’s ecosystems (it’s role)  two species cannot coexist in a community if they occupy the same niche


8 3. Resource partitioning  if two species have the same niche, the less competitive one will either be driven from the area, or will evolve through natural selection to use a different set of resources

9 4. Character displacement  The tendency for characteristics to be more divergent in sympatric (geographically overlapping) populations of two species than in allopatric (geographically separate) populations of the same two species

10 B. Predation  beneficial to one organism but not the other  one organism eats another  includes herbivory (eating part of a plant), parasitism (parasite living on host)

11 1. Predator adaptations  acute senses to locate prey  many have claws, teeth, fangs, stingers, poison  generally fast and agile if they have to pursue prey

12 2. Animal defenses against predators  Passive defenses: hiding, chemical toxins  Active defenses: escaping, defending themselves, warning calls

13 Animal defenses against predators  Adaptive coloration  camoflauge – cryptic coloration to blend with environment  aposematic coloration – bright coloration of animals that have chemical toxins dangerous to predators Can you see me?

14 Animal defenses against predators  Mimicry – “copycat” adaptation  Batesian mimicry – harmless species mimics a harmful model (ex. larvae puffs up and resembles cobra) I’m Harmless!!!

15 Animal defenses against predators  Mullerian mimicry two unpalatable species resemble each other  predators learn more quickly about danger of the appearance

16 3. Parasites and Pathogens as predators  host harmed in the process  endoparasites – live within their host (tapeworm)  ectoparasites – feed on external surface of host (mosquito)  parasitoidism – insects lay eggs on living host on living host

17 4. Herbivory  Organism eats part of a plant or alga  ex. Cattle, many invertebrates, manatee  Herbivores may have adaptations such as chemical sensors to detect toxins, specialized teeth

18 5. Plant defenses against herbivores  Chemical toxins  Spines  Thorns  Used since plants cannot run from predator

19 C. Mutualism  interspecific interaction that is beneficial to both species  often requires coevolution of adaptations in both species  if one is harmed, the other is usually harmed as well

20 Examples of Mutualism  microorganisms in digestive system of termites and ruminants (help digest cellulose)  Photosynthesis by algae in tissue of coral There’s bacteria in my belly Who knew!!!

21 4. Commensalism  interaction between species that benefits only one of the species but no harm to the other  ex. algae growing on shell, birds eating insects flushed up by cows MOOOOYummy Bugs

22 III. Biodiversity  Species diversity in a community

23 Species Diversity  The variety of different kinds of organisms that make up the community

24 Species Diversity  Species Richness  number of species that a community can contain  Relative Abundance  The proportion of each species represents of all individuals in the community

25 Which community is more diverse???

26  Community 1 and 2 are equal in their species richness (both have 4 different species)  Community 1 is more diverse because there is equal representation of all 4  Community 2 has a large amount of Species A  Community 1 has greatest heterogeneity (looks at species number and relative abundance

27 IV. Trophic structures  feeding relationships between organisms Quaternary Consumer (Carnivore) Tertiary Consumer (Carnivore) Secondary Consumer (Carnivore) Primary Consumers (Herbivores/Zooplankton) Primary Producers (plant/phytoplankton)

28 A. Food Chain  Transfer of food energy from it’s source in plants through herbivores to carnivores and eventually to decomposers  Each link makes a trophic level  Each food chain has only four or five links due to inefficient energy transfer as you move up the chain  Longer food chains may not be able to recover as quickly from environmental change


30 B. Food Web  more than one food chain hooked together

31 Dominant species  have the highest abundance or the highest biomass  exert control over occurrence and distribution of other species

32 Keystone species  exert control on community structure by their ecological role (niche)  may help to maintain diversity and balance in community  ex. sea otter eats sea urchin eats algae  remove sea otter (keystone) and algae population goes down  add sea otter – algae population increases

33 Example of Keystone Species  Removal experiment  Robert Paine and Sea Star – Pisaster is a keystone predator of mussels  With Pisaster – many species able to coexist  Without Pisaster – mussels able to overtake area eliminating many other species


35 Foundation Species  Exert influence on a community by causing physical changes in the environment  ex. Beaver building a dam can transform the landscape on both sides  Can be positive or negative on other species

36 V. Disturbances  storms, fires, floods, drought, overgrazing, human activities  may upset balance or equilibrium in community

37 Ecological succession  transition in the biological species composition of a community usually following a disturbance

38 Primary succession  succession that begins in a virtually lifeless area where soil has not yet formed (like Hawaii)  Autotropic bacteria  lichens/mosses  soil  other plants  animals

39 Secondary succession  existing community has been cleared by a disturbance that leaves soil intact  Often these areas return to something like the original state

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