Download Chapter 54 – Community Ecology Ecological Niche • Species` total

Chapter 54 – Community Ecology
Ecological Niche
 Species’ total use of biotic & abiotic resources; it’s ecological role
 Everything affecting survival, reproduction, diet, water needs, space required, temps it tolerates
 Fundamental Niche
o Total niche that species can perform w/out competition
 Realized Niche
o Species performs only part of fundamental niche b/c of competition
 Generalist Species
o Broad niche
o Live in many diff. places, eat variety of food, tolerate wide range of conditions
 Specialist Species
o Narrow niche
o May live in only 1 habitat, eat a few types of food, tolerate narrow range of environmental
conditions
Intraspecific Competition
 B/w individuals of the same species
Interspecific Interactions
 Relationships b/w 2 species
 Affects survival & reproduction of each species
 Effects summarized as…
o Positive (+), Negative (–), No effect (0)
 Interspecific Competition
o (–/– interaction)
o Occurs when species compete for a limiting resource
 Not always a direct fight
o Competitive Exclusion Principle
 No two species occupy same niche
 One will have advantage over other & eliminate it
 Loser migrates, adapts, or dies
o Realized niche
o Resource Partitioning
 Reduces niche overlap
 Use resources at different times, ways, or in different places
 Allows similar species to coexist in community
 Predation
o (+/– interaction)
o Predator kills & eats prey
o Predator adaptations – claws, teeth, fangs, stingers, poison, mimicry or camouflage
o Prey’s Defense
 Behavioral – hiding, fleeing, form herd/school, self-defense, & alarm calls
 Physical – porcupine quills
 Chemical – produce or acquire toxins, bad smell
 Cryptic Coloration
 Camouflage Coloration
 Aposematic Coloration
 Warning Coloration
 Batesian Mimicry
 Good mimics bad
 Müllerian Mimicry
 Bad mimics bad
o Coevolution
 Two interacting species can drive evolution of each other
 Evolutionary arms race b/w predator & prey
 Parasite & host

Herbivory
o (+/– interaction)
o Herbivore eats parts of a plant or algae
 Symbiosis
o Relationship where two species live in direct & intimate contact together
o Parasitism
 (+/– interaction)
 Parasite gets nutrients from host, which is harmed (not killed)
 Endoparasites – live inside host
 Ectoparasites – live on host
 Parasite can also use host’s energy
 Parasites
 Often have complex life cycle involving a number of hosts
 Can change behavior of host to increase their own fitness
o Mutualism
 (+/+ interaction)
 Obligate – where one species cannot survive w/o other
 Facultative – both species can survive alone
o Commensalism
 (+/0) interaction
 One benefits, other unaffected
Community Diversity
 Variety of organisms make up community
 Two Factors:
o Species Richness – total number of different species
o Relative Abundance – proportion of species in community
 Theory of Island Biogeography
o Species richness depends on:
 Rate of immigration
 Rate of extinction
o Balance b/w 2 rates gives equilibrium point (species richness on island)
o Rates affected by island’s
 Size
 Distance from mainland
o Small Island
 Low immigration (small target)
 High extinction (fewer resources)
o
o
o
Big Island
 High immigration (big target)
 Low extinction (more resources)
Closer to land = more immigration
Summary
 Most species richness if:
 Big island
 Close to mainland
 Least species richness if:
 Small island
 Far from mainland
Specie’s Role
 Dominant Species
o Most abundant or have highest biomass
 Total dry mass of all individuals in population
o Exert powerful control over who, how many, & where other species are

Invasive Species
o Species that migrate or are introduced
o aka Introduced, Alien, Exotic
o Often generalists, spread rapidly, no predators, parasites, or pathogens
 Keystone Species
o Exert strong control on community by their ecological niches in comparison to their small
abundance
 Foundation Species (aka Ecosystem Engineers)
o Cause physical changes in environment affecting community structure
Disturbances & Recovery
 Disturbance
o Event that changes a community, removes organisms from it, & alters resource availability
o Fire, storm, flood, drought, overgrazing, human activity
 Ecological Succession
o Gradual change in community composition in a given area over a long period of time
o Just a GENERAL pathway
o Primary Succession
 Begins in lifeless areas w/ no soil; takes a long time
 Lava bed, retreating glacier, abandoned parking lot
 Weathering
 Rocks break down & release nutrients…
o Physical – water; freezing/ melting, rain impact
o Chemical – things in water & atmospheric compounds
o Biological – lichens
 Early Successional Plants
 Pioneer species attach to rocks
 Arrive as seed/spore brought by wind or animal
o Lichens – mutualism b/w alga (photosynthesis) & fungus (protection)
o Mosses – primitive plant
 Pioneers Create Soil
o Trap wind-blown particles/detritus
o Lichens secrete mild acids that further breakdown rocks
o Mosses trap water like a sponge
o Waste & dead matter from pioneers
o After 100s-1000s yrs; soil may be thick & fertile enough for…
 Midsuccessional Plants
 Herbs, grasses, & low shrubs
 Create shade; kill off moss & lichens
 Fast growing, shade intolerant trees arrive
 Late Successional Plants
 Shade tolerant seedlings arrive
 Tall trees w/ long life spans
 Midsuccessions dieoff b/c seedlings shade intolerant
 Climax Community
o Stable group of plants & animals that is end result of succession process
o Plants replaced by same species
o High biodiversity
o Photosynthesis = Respiration
o Secondary Succession
 Occurs after disturbance, removal, or destruction of ecosystem
 Still has soil left
 Seeds germinate that remain from before disturbance, or are brought from elsewhere
 Much faster than primary b/c soil already present
o
Prescribed Burning
 Natural habitat not always climax community
 Periodic fires prevent climax
 Gets rid of fast burning plants
o Small weeds & scrub brush
 Keeps high native biodiversity
 Florida Long Leaf Pine
 150 yrs to get 100+ feet tall
 Live up to 500 yrs
 Very Fire Resistant
o Thick layers of bark
o Leaves occur high off ground
o Needle-like leaves