Transcript ppt

Population Ecology
I. Attributes
II.Distribution
III. Population Growth – changes in size through time
IV. Species Interactions
V. Dynamics of Consumer-Resource Interactions
VI. Competition
VII. Mutualisms
A. Overview
1. Dynamics
- NET fitness benefit to both populations
- diffuse (many partners) or species specific
- facultative (not necessary) or obligate
- strength of feedback loop depends on
the degree of “obligateness”
A. Overview
1. Dynamics
2. Historical Importance
- endosymbiotic origin of Eukaryotes
A. Overview
1. Dynamics
2. Historical Importance
- endosymbiotic origin of Eukaryotes
- symbiotic origin of multicellularity
A. Overview
1. Dynamics
2. Historical Importance
- endosymbiotic origin of Eukaryotes
- symbiotic origin of multicellularity
- symbiotic efficiencies in energy
harvest by nearly all life forms
Corals and zooxanthellae
Frugivory
Aphid farming by ants
Gleaners
Pollination
Protozoans in Termites
A. Overview
1. Dynamics
2. Historical Importance
- endosymbiotic origin of Eukaryotes
- symbiotic origin of multicellularity
- symbiotic efficiencies in energy
harvest by nearly all life forms
- at planetary scale, there are
complementary and dependent roles
White – increase reflectance,
lower temperature of planet.
White flower doesn’t
overheat, but doesn’t work
well at low temps.
Black – increase absorption,
increase temperature of
planet. Work well at low
temps, but overheat at high
temps.
A. Overview
B. Modeling Mutualism
Effect of second
species increases
population growth
dN1/dt = rN1 ((K1-N1 + aN2)/K1)
dN2/dt = rN2 ((K2-N2 + bN1)/K2)
N1 increases (beneath its K), but N2 declines because there aren’t enough N1’s
to allow N2 to maintain this large a population.
Both get bigger and
bigger (run-away)
N2 reaches its K when N1 = 0. But
N2 > K when N1 > 0.
Stable equilibrium – both maintained at a stable equilibrium above K.
Obligate mutualism – a minimum number of partners are required to maintain a
population above zero. So, there needs to be at least 50 N2 individuals for N1 to
grow (above its isocline). To sustain more N1 individuals, more N2 are needed.
So here, there are 170 N2 individuals and that’s enough for the 5 individuals
In the N1 population to grow. However, with only 5 N1 individuals, N2 declines.
This eventually causes a decline in N1, as they are obligate mutualists.
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
1-Esophagus
2-Stomach
3-Small Intestine
4-Cecum (large intestine) - F
5-Colon (large intestine)
6-Rectum
Low efficiency - high throughput...
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
Rhizobium bacteria fix nitrogen, breaking N2
into N, which reacts with water and oxygen to
form NO2 and NO3 that can be absorbed by
plant. Infect legumes; plant provides sugars.
C. Types of Mutualism
Trophic Mutualisms – help one another get nutrients
Ectomycorrhiza and
“Endo”- or arbuscular mycorrhizae
Trophic Mutualisms – help one another get nutrientss
Lichens – an alga and a fungus
Trophic Mutualisms – help one another get nutrients
Mixed foraging flocks
Defensive Mutualisms – Trade protection for food
Defensive Mutualisms – Trade protection for food
Ants ‘farm’ the fungus, culturing it on a chewed-leaf mulch.
Defensive Mutualisms – Trade protection for food
Acacia and Acacia ants
Induced and Constitutive Defenses in Acacia.
The species in the right-hand column
have mutualistic relationships with
ant species - the ants nest in the
thorns. Those on the left can attract
ants with extra-floral nectary
secretions, but the ants do not nest.
The Acacia species on the left
increase their nectar secretions after
damage, inducing wandering ants to
come visit and stay a while.
The species on the right have to
support the ant colonies all the time,
and nectar production is uniformly
high and unaffected by damage.
Induced and Constitutive Defenses in Acacia.
The species in the right-hand column
have mutualistic relationships with
ant species - the ants nest in the
thorns. Those on the left can attract
ants with extra-floral nectary
secretions, but the ants do not nest.
The Acacia species on the left
increase their nectar secretions after
damage, inducing wandering ants to
come visit and stay a while.
The species on the right have to
support the ant colonies all the time,
and nectar production is uniformly
high and unaffected by damage.
WHICH CAME FIRST??
Induced and Constitutive Defenses in Acacia.
Induced defenses first,
then the obligate
relationship evolved…
Todd M. Palmer, Maureen L. Stanton, Truman P. Young, Jacob R. Goheen, Robert M.
Pringle, Richard Karban. 2008. Breakdown of an Ant-Plant Mutualism Follows the Loss
of Large Herbivores from an African Savanna. Science 319:192-195.
Fig. 1. Rewards produced in the presence
(white bars) and absence (gray bars) of
large herbivores by A. drepanolobium
occupied by different species of Acacia
ants. Ant species' abbreviations are
indicated as: Cs, C. sjostedti; Cm, C.
mimosae; Cn, C. nigriceps; Tp, T. penzigi.
Plants produce fewer rewards when
large herbivores are absent and
herbivory rates are LOWER. Bribing
ants to stay and protect them is less
important.
Todd M. Palmer, Maureen L. Stanton, Truman P. Young, Jacob R. Goheen, Robert M.
Pringle, Richard Karban. 2008. Breakdown of an Ant-Plant Mutualism Follows the Loss
of Large Herbivores from an African Savanna. Science 319:192-195.
Fig. 2. The proportion of host
trees occupied by the four
Acacia-ant species in the
presence of large herbivores
(white bars) and in plots from
which large herbivores had
been excluded (gray bars) for
10 years.
And if large herbivores are
excluded and plants produce
less nectar, then some ants
abandon the trees (the
mutualist).
“Our results indicate that the large herbivores typical of African savannas
have driven the evolution and maintenance of a widespread ant-Acacia
mutualism and that their experimentally simulated extinction rapidly tips the
scales away from mutualism and toward a suite of antagonistic behaviors
by the interacting species. Browsing by large herbivores induces greater
production of nectary and domatia rewards by trees, and these rewards in
turn influence both the behavior of a specialized, mutualistic ant symbiont
and the outcome of competition between this mutualist and a non-obligate
host-plant parasite. Where herbivores are present, the carbohydrate
subsidy provided by host trees plays a key role in the dominance of the
strongly mutualistic C. mimosae, which is consistent with the hypothesis
that plant exudates fuel dominance of canopy ant species that are
specialized users of these abundant resources (28). In the absence of large
herbivores, reduction in host-tree rewards to ant associates results in a
breakdown in this mutualism, which has strong negative consequences for
Acacia growth and survival. Ongoing anthropogenic loss of large herbivores
throughout Africa (29, 30) may therefore have strong and unanticipated
consequences for the broader communities in which these herbivores
occur.”
Todd M. Palmer, Maureen L. Stanton, Truman P. Young, Jacob R. Goheen, Robert M.
Pringle, Richard Karban. 2008. Breakdown of an Ant-Plant Mutualism Follows the Loss
of Large Herbivores from an African Savanna. Science 319:192-195.
Defensive Mutualisms – Trade protection for food
Ants ‘farm’ aphids and drink their ‘honeydew’
Cleaning Mutualisms – Trade cleaning for food
Cleaning Mutualisms – Trade cleaning for food
Cleaning Mutualisms – Trade cleaning for food
Fish visit non-cheating
cleaners more
And watched cleaners
cheat less.
Dispersive Mutualisms – Trade dispersal for food
Dispersive Mutualisms – Trade dispersal for food
Dispersive Mutualisms – Trade dispersal for food
Orchids, Euglossine Bees, and Wasps.
Dispersive Mutualisms – Trade dispersal for food
Dispersive Mutualisms – Trade dispersal for food
Not mutualism
(commensal or
parasitic)