Transcript Indirect Interactions Darwin — Lots of “Humblebees” around

Second Exam: Thursday 29 October 2015
Covers Chapters 5, 8, 9, 10, and 11
Lectures 10 to 19 plus
Agriculture
Global Warming
The Vanishing Book of Life on Earth
Plastics
Intelligent Design?
The Weakest Link
Lecture # 18
Technology
27 October 2015
Economics
200 mph winds -- Strongest hurricane in 50 years
Intersexual vs. intrasexual (epigamic) sexual selection
Mating preferences in Drosophila and pigeons
Certainty of Maternity, Uncertainty of Paternity
“Battle of the sexes”
Cuckoldry —> jealousy
Desertion —> Mating Rituals, Complex Courtship
Sex that invests most is most choosy about mates
Natural selection produces a correlation between
male genetic quality and female preference
“Sexy son” phenomenon (females cannot afford to mate
with males that are not attractive to other females)
Male Reproductive Success in Sage Grouse
Game Theoretic Approaches
Prisoner's dilemma:
Two suspects, A and B, are arrested by the police. The police have insufficient
evidence for a conviction, and, having separated both prisoners, each of them
is offered the same deal: if one testifies for the prosecution against the other
and the other remains silent, the betrayer goes free and the silent accomplice
receives the full 10-year sentence. If both stay silent, the police can sentence
both prisoners to only six months in jail for a minor charge. If each betrays the
other, each will receive a two-year sentence. Each prisoner must make the
choice of whether to betray the other or to remain silent. But neither prisoner
knows for sure what choice the other prisoner will make. So the question this
dilemma poses is: What will happen? How will the prisoners act?
Prisoner's Dilemma
Prisoner B Stays Silent
Prisoner A
Stays Silent
Both serve 6 months
Prisoner A
Prisoner A goes free
Betrays
Prisoner B serves 10 years
Prisoner B Betrays
Prisoner A serves 10 years
Prisoner B goes free
Both serve two years
http://plato.stanford.edu/entries/prisoner-dilemma/
Game Theoretic Approaches
Costs versus benefits of behaviors
“tit for tat” strategy can lead to cooperation
(“the future casts a long shadow back
on the present” -- Axelrod)
Evolutionarily stable strategies = ESS
(a tactic that when
present in a population,
cannot be beaten)
John Maynard Smith
Evolution of Self Deceit
Subconscious mind
Polygraph playback experiments
Evolution of Self Deceit
Subconscious mind
Polygraph playback experiments
Evolution of Self Deceit
Subconscious mind
Polygraph playback experiments
Evolution of Self Deceit
Subconscious mind
Polygraph playback experiments
Fool Yourself
The Better to Fool Others
Summary of Direct Pairwise Interactions Between Two Populations
__________________________________________________________________________
Species
Type of Interaction
A
B
Nature of Interaction
__________________________________________________________________________
Competition
–
–
Each population inhibits the other
Predation, parasitism,
and Batesian mimicry
+
–
Population A, the predator, parasite,
or mimic, kills or exploits members
of population B, the prey, host, or model
Mutualism,
Müllerian mimicry
+
+
Interaction is favorable to both (can
be obligatory or facultative)
Commensalism
+
0
Population A, the commensal, benefits
whereas B, the host, is not affected
Amensalism
–
0
Population A is inhibited, but B is
unaffected
Neutralism
0
0
Neither party affects the other
__________________________________________________________________
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
bees —> clover
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
bees ——> clover
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
mice ——o bees ——> clover
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
cats —o mice ——o bees ——> clover
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
spinsters —> cats —o mice —o bees —> clover
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
spinsters —> cats —o mice —o bees —> clover —> beef
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
spinsters —> cats —o mice —o bees —> clover —> beef —> sailors
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
spinsters —> cats —o mice —o bees —> clover —> beef —> sailors —> naval
prowess
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
—————————————————>
spinsters —> cats —o mice —o bees —> clover —> beef —> sailors —> naval
prowess
Path length of seven! Longer paths take longer (delay)
Longer paths are also weaker, but there are more of them
Indirect Interactions
Trophic “Cascades”
Top-down,
Bottom-up
Competitive Mutualism
Complex Population Interactions
Rob Colwell
Mutualistic Interactions and Symbiotic Relationships
Mutualism (obligate and facultative) Termite endosymbionts
Commensalisms (Cattle Egrets)
Examples:
Bullhorn Acacia ant colonies (Beltian bodies)
Caterpillars “sing” to ants (protection)
Ants tend aphids for their honeydew, termites cultivate fungi
Bacteria and fungi in roots provide nutrients (carbon reward)
Bioluminescence (bacteria)
Endozoic algae (Hydra), “kidnapped” chloroplasts
Endosymbiosis (Margulis) mitochondria & chloroplasts
Birds on water buffalo backs, picking crocodile teeth
Figs and fig wasps (pollinate, lay eggs, larvae develop)
Brown Hydra
Green Hydra
Nudibranchs
Green sea slug
Hydra
Runaway Sexual Selection (Fisher)
Handicap Hypothesis (Zahavi)
Leks
Sensory Exploitation Hypothesis
Internal versus External Fertilization
Alternative mating tactics
Satellite males
Ecological Sexual Dimorphisms
Ratites (bushland tinamou)
Bower birds
Spiteful behavior
Summary of Direct Pairwise Interactions Between Two Populations
__________________________________________________________________________
Species
Type of Interaction
A
B
Nature of Interaction
__________________________________________________________________________
Competition
–
–
Each population inhibits the other
Predation, parasitism,
and Batesian mimicry
+
–
Population A, the predator, parasite,
or mimic, kills or exploits members
of population B, the prey, host, or model
Mutualism,
Müllerian mimicry
+
+
Interaction is favorable to both (can
be obligatory or facultative)
Commensalism
+
0
Population A, the commensal, benefits
whereas B, the host, is not affected
Amensalism
–
0
Population A is inhibited, but B is
unaffected
Neutralism
0
0
Neither party affects the other
__________________________________________________________________
Intraspecific competition (between individuals within spp.)
Interspecific competition (between members of different spp.)
Exploitation competition (resource depression)
Interference competition (direct antagonistic encounters)
Indirect Interactions
Darwin — Lots of “Humblebees” around villages
—————————————————>
spinsters —> cats —o mice —o bees —> clover —> beef —> sailors —> naval
prowess
Path length of seven! Longer paths take longer (delay)
Longer paths are also weaker, but there are more of them
Dan Janzen
Euglossine bees
Orchid fragrances (epiphytes)
Male bees use orchid chemicals as base for production of
pheromones to attract female bees (travel up to 23 km)
pollinate rare and diverse orchids, allowing sparsely
distributed plants to occur at astonishing low densities
Heliconius tropical butterflies
get amino acids from pollen
Larry Gilbert
Various Aspects of the Association of Cattle Egrets with Cattle
________________________________________________________
Number of
Number Percent
Associated Egrets
Category
of Cattle Cattle
Expected
Observed
___________________________________________________________________
Grazing in sun 735
Grazing in shade 55
Standing in sun 146
Standing in shade257
Lying in sun
503
Lying in shade 143
Walking
39
Total
1878
39.1
2.9
7.8
13.7
26.8
7.6
2.1
100.0
239
439
18
21
48
46
84
17
164
69
47
17
13
3
______________________
612
________________________________________________________
Various Aspects of the Association of Cattle Egrets with Cattle
______________________________________________________________________
Mean
Number
Per Minute
Number of Times
Count Was Higher
Than for Opposite
Egret
Number of
Associated Egrets
______________________________________________________________________
Feedings, N = 84
Associated
2.34
58
69
Nonassociated 1.71
26
31
Steps, N = 62
Associated
Nonassociated
20.1
32.1
7
55
Feeding/step, N = 59
Associated
Nonassociated
0.129
0.051
52
7
11
89
Harold Heatwole
88
12
__________________________________________________________
Interspecific Competition leads to Niche Diversification
Two types of Interspecific Competition:
Exploitation competition is indirect, occurs when a
resource is in short supply by resource depression
Interference competition is direct and occurs via
antagonistic encounters such as interspecific
territoriality or production of toxins
Direct versus Indirect Interactions
Exploitation vs. Interference competition
Apparent Competition
Competitive Mutualism
Facilitation
Food Chain Mutualism
Trophic Cascades (top-down, bottom up)
Complex Population Interactions (Colwell’s Plant-Pollinator System)
Mutualisms
Euglossine bees and orchids
Heliconius butterflies (larval nitrogen reserves)
Cattle Egret Commensalism
Gause’s competition lab experiments
Competitive Exclusion
Georgii F. Gause
Coexistence of
two species of
Paramecium
G. F. Gause
Outcome of Competition Between Two Species of Flour Beetles
_______________________________________________________________________________
Temp.
(°C)
Relative
Humidity
(%)
Climate
Single Species
Numbers
Mixed Species (% wins)
confusum castaneum
_______________________________________________________________________________
34
70
Hot-Moist
confusum = castaneum
0
100
34
30
Hot-Dry
confusum > castaneum
90
10
29
70
Warm-Moist
confusum < castaneum
14
86
29
30
Warm-Dry
confusum > castaneum
87
13
24
70
Cold-Moist
confusum <castaneum
71
29
24
30
Cold-Dry
confusum >castaneum
100
0
_______________________________________________________________________________
Recall the Verhulst-Pearl Logistic Equation
dN/dt = rN [(K – N)/K] = rN {1– (N/K)}
dN/dt = rN – rN (N/K) = rN – {(rN2)/K}
dN/dt = 0 when [(K – N)/K] = 0
[(K – N)/K] = 0 when N = K
dN/dt = rN – (r/K)N2
Inhibitory effect of each individual
On its own population growth is 1/K
Assumes linear response to crowding,
instant response (no lag),
r and K are fixed constants
S - shaped sigmoidal population growth
Verhulst-Pearl Logistic
Lotka-Volterra
Competition Equations
competition coefficient
aij = per capita competitive effect
of one individual of species j on
the rate of increase of species i
Alfred Lotka
Vito Volterra
dN1 /dt = r1 N1 ({K1 – N1 – a12 N2 }/K1)
dN2 /dt = r2 N2 ({K2 – N2 – a21 N1 }/K2)
Isoclines:
(K1 – N1 – a12 N2 )/K1 = 0 when N1 = K1 – a12 N2
(K2 – N2 – a21 N1 )/K2 = 0 when N2 = K2 – a21 N1