Transcript IB Ecology Option G1

Option G:
Ecology & Conservation
(22 hours)
G1:
Community Ecology
(5 hours)
G.1.1 Outline the (abiotic)
factors that affect the
distribution of plant species--
• Example: sand dune community
• Temperature (xref- photosynthesis- 3.8.8) & Water
– Foredune—very hot in summer, little water
• Grass adapted to conditions
• Long roots find water; leaves can curl to save
water and resist heat
– Mature dune—much cooler, more moist
• More species diversity
• Example – @ “forest” floor--ferns (low light,
moist conditions)
G.1.1 Outline the (abiotic)
factors that affect the
distribution of plant species--
• Light (xref- photosynthesis- 3.8.8)
– Grasses in high light
• Thin leaves reduce water loss, withstand heat
– Ferns – low light
• Wide leaves capture the small amt light / shade
• Soil pH (xref- pH on enzymes- 3.6.3)
– pH varies among dune regions
– Yellow dune- soil pH 7.5 (grass here too, thrives @
pH)
– Grey dune-decomposition of lots grasses, soil more
rich, more acidic (acid-loving heathers here)
G.1.1 Outline the (abiotic)
factors that affect the
distribution of plant species--
• Salinity
– Foredunes get salt spray
• Grasses can tolerate it
– Grey dune less salty
• Small shrubs, mosses, lichen
• Mineral nutrients
– Grey dune – diversity of plants, older region,
has mineral content to support shrubs, etc.
– Mature dune – way inland, lots of nutrient-rich
soil, oldest region (soil building up 100s yrs),
can support large trees (ash, birch, oak)
G.1.2 Explain the factors that affect the distribution of
ANIMAL species, including
• Example: Indiana Dunes, Lake Michigan
• Temperature
– Animals adapted for hot/cold temps
– Sand wolf spider: foredune dweller, extreme high
temps—lives in deep burrow (behavioral
adaptation)
– Woodland spider: live in trees (shade, cooler)mature dune
• Water
– Water for eggs, aquatic animals for food
– Heron-catches fish/frogs, lives near water
– Woodpecker-eats insects in trees, lives in mature
dune
G.1.2 Explain the factors that affect the distribution of
ANIMAL species, including
• Breeding sites
– Nesting sites
– Protection from sun, wind; mature dune, wetlands
– Habitat loss! 
• Food supply
– Generalists, specialists
– Raccoons, skunks, foxes-move to where food is
located; nocturnal
– Rabbits-burrows in foredune, near grass (food)
• Territory
– Packs of coyotes, scent to mark space
– May or may not overlap
G.1.3 Describe one method of random sampling, based on quadrat methods, that is
used to compare the population size of two plant or two animal species.
• Statistics- Topic 1!!!
• Easier than counting every individual
• Random = each organism has equal chance of being selected
for the count
• Quadrat: square (certain size, dep. on organism)
– Map the whole area
– Determine quadrat size
– Use a #d grid over the map
– Random # table to decide which squares (quadrats) to
sample
– Count # of xxxx and # of yyyy within sample quadrats
– Calculate avg # xxxx and avg # yyyy in each
– Multiply avg (for xxxx, for yyyy) x total # quadrats in whole
area to estimate population of xxxx and yyyy
G.1.4 Outline the use of a transect to correlate the
distribution of plant or animal species with an abiotic
variable.
• Common for studying distribution of plants/animals in
ecosystem, abiotic factors affecting it
• Use a tape/line through the area
• Every 10-20 m along tape, mark a quadrat (use consistent
size for all)
• Identify, count plant/animal species of interest in quadrats
• Measure abiotic feature in each quadrat (temp, light, soil pH,
water, mineral nutrients)
• Determine pattern of distrib of species  correlation w/abiotic
factor??
Hmmm...quadrat or transect??
Depends on if habitat’s fairly uniform –or-
if you see a progression along an environmental
gradient
G.1.5 Explain what is meant by the niche concept,
including an organism’s spatial habitat, its feeding
activities its interactions with other species.
• Niche = role in ecosystem
• Spatial habitat: where it lives
– Presence of organism changes the habitat (frogs
burrow in mud @ pond bank)
• Feeding activities: keep prey pop in check
– Frog eats larvae of mosquitoes, flies, etc.
• Interactions w/other species: competition, herbivory,
predation, parasitism, mutualism
– Heron is predator for frog
– Frog is host to parasite
Who Cares?!?!?!?
• We Do! 
• Ecologists study niches to measure impacts on
populations
• Danger of extinction  need to understand as
much as possible about species
– Habitat Loss = biggest threat 
G.1.6 Outline the following interactions between
species, giving two examples of each:
• Competition (2 sp compete for same resource)
– Coyote (grassland) & red fox (edges of forests &
meadows): both eat small rodents, birds; more
farmland reduces forest  fox overlapping
w/coyote, compete for food
– Natterjack toad & common toad: disturbance in
coastal dunes in UK, limiting habitat for both
• Herbivory (primary consumer feeds on producer:
growth of producer critical to primary consumer’s
survival)
– Rabbits eat grass in sand dune ecosystem
– Monarch b’fly larvae eat leaves of milkweed
G.1.6 Outline the following interactions between
species, giving two examples of each:
• Predation (consumer-pred. eats consumer-prey; # prey affects #
pred, vice versa)
– Canadian lynx and arctic hare: lynx pop changes followed by
hare pop changes
– Blue heron pred. for frogs in sand dune ponds
• Parasitism (lives in/on host, depends on host, host is harmed)
– Plasmodium (malaria in humans) reproduces in human liver
and RBCs; part of life cycle in Anopheles mosquito (vector,
transmits from human to human)
– Leeches—hosts are humans/mammals, puncture skin &
secrete enzyme to prevent clotting
• Mutualism (2 sp live together, both benefit)
– Lichen= algae + fungi (photosynthesis, make food; absorb
minerals algae need)
– Rhizobium = N-fixing bacteria in legume roots (fixes N for
plant; plant makes carbs for bacteria)
– Clownfish & anemone (fish has mucusto protect it, fish lures
other fish to anemone...food for anemone...clownfish eats
leftovers
G.1.7 Explain the principle of competitive exclusion.
• No two species in same community can occupy
same niche: one will be excluded
– 1934, Gause: Paramecium expts
– Interspecific competition
• Red fox & coyote
– If they do inhabit same
area, same niche...
– 1 will die out, other will
survive
Fig. 19.1. Competitive exclusion of one species of the ciliate
protozoan Paramecium by another.
Data from Gause (Gause, G.F. 1934. The Struggle for
Existence. Williams and Wilkins, Baltimore, MD.).
G.1.8 Distinguish between fundamental niche & realized
niche.
• fundamental niche of a species
– potential mode of existence, given the adaptations of
the species
– Complete range of biological and physical conditions
within which it can live
– (red fox used to live @ forest edge & meadows)
• realized niche of a species
– actual mode of existence, narrower range
– results from its adaptations and competition with other
species
– (now red fox habitat shrunk, competing w/coyote, in the
realized niche)
G.1.9 Define biomass.
•
•
•
•
Total mass of organic matter
Carbs, lipids, proteins
DRY the matter 1st to remove water content
g m-2 yr -1
G.1.10 Describe one method for the measurement of
biomass of different trophic levels in an ecosystem.
• Aim 8: Ethical issues of returning the species and
destructive techniques should be considered.
• Tables/charts to get biomass of animal vs size/weight  ,
small plants too 
• Biomass of ecosystem of terrestrial community:
– Measure total area of forest
– Divide into small area (grids, plots)
– Sample one plot
– Measure size of each plant species, including trees
(height, diameter) & low-growing.
– Cut down ALL the trees and vegetation on that ONE
plot
G.1.10 Describe one method for the measurement of
biomass of different trophic levels in an ecosystem.
• Dry all plant samples (circulating drying oven)
• Math. Model: relationship b/w weight and height of
each plant species and its biomass
• Sample other plots for height and size only—no need
to cut down/dry/killlllll....use the model!
• ANIMALS: set traps in the plot, weigh, measure & use
tables to get biomass
• Avg data for all species per plot
• Multiply x # plots in ecosystem  biomass for whole
ecosystem
• Seasonal/yearly sampling to track changes over time