Transcript Ground Rules, exams, etc. (no “make up” exams) Text: read

Second Exam: Thursday 2 April 2015
Covers Chapters 5, 8, 9, and 10
Lectures 10 to 19 plus
Agriculture
Global Warming
The Vanishing Book of Life on Earth
Plastics
Intelligent Design?
The Weakest Link
Technology
Economics
Social Behavior
Hermits must have lower fitness than social individuals
Clumped, random, or dispersed (variance/mean ratio)
mobility = motility = vagility (sedentary sessile organisms)
Fluid versus Viscous Populations
Use of Space, Philopatry
Individual Distance, Daily Movements
Home Range
Territoriality (economic defendability)
Resource in short supply
Feeding Territories
Nesting Territories
Mating Territories
Sexual Reproduction
Monoecious (Hermaphrodites) versus Diecious
Evolution of Sex —> Anisogamy
Diploidy as a “fail-safe” mechanism
Costs of Sexual Reproduction (halves heritability!)
Facultative Sexuality (Cladocera, Daphnia)
Protandry <—> Protogyny (Social control)
Parthenogenesis (unisexual species)
Possible advantages of sexual reproduction include:
two parents can raise twice as many progeny
mix genes with desirable genes (enhances fitness)
reduced sibling competition
heterozygosity
biparental origin of many unisexual species
Four Possible Situations Involving an Individual’s
Behavior and Its Influence on a Neighbor
__________________________________________________________________
Neighbor(s) Gain
Neighbor(s) Lose
__________________________________________________________________
Individual Gains
Pseudo-altruistic behavior
Selfish behavior
(kin selection)
(selected for)
__________________________________________________________________
Individual Loses
True altruistic behavior
Mutually disadvanta(counterselected)
geous behavior
(counterselected)
_________________________________________________________________
W. D. Hamilton (1964)
Kin Selection
Inclusive Fitness
Hamilton’s rule: r n b – c > 0
r = coefficient of relatedness
n = number of relatives that benefit
b = benefit received by each recipient
c = cost suffered by donor
rnb > c
“Adaptive Geometry of a Selfish Herd”
“Adaptive Geometry of a Selfish Herd”
Eusocial Insects
Hymenoptera (“thin wings”)
Ants, bees, wasps, hornets
Workers are all females
Haplodiploidly
Isoptera (“same wings”)
Termites (castes consist of both sexes)
Endosymbionts
Parental manipulation
Cyclic inbreeding
White-Fronted Bee Eaters, Kenya
Helpers at the Nest in White-Fronted Bee Eaters in Kenya
__________________________________________________________________
Breeders
r*
Number of Cases
% Cases
__________________________________________________________________
Father x Mother
0.5
78
44.8
Father x Stepmother
0.25
17
9.8
Mother x Stepfather
0.25
16
9.2
Son x Nonrelative
0.25
18
10.3
Brother x Nonrelative
0.25
12
6.9
Grandfather x Grandmother
0.25
5
2.9
Half brother x Nonrelative
0.13
3
1.7
Uncle x Nonrelative
0.13
2
1.1
Grandmother x Nonrelative
0.13
1
0.6
Grandson x Nonrelative
0.13
1
0.6
Great grandfather x Nonrelative
0.13
1
0.6
Nonrelative x Nonrelative
0.0
20
11.5
Total
174
100.0
__________________________________________________________________
* r = coefficient of relatedness.
Reciprocal Altruism (Trivers 1971)
Donor ––->
<---- Recipient
Small costs, large gains, reciprocated
Sentinels
Robert Trivers
Biological basis for our sense of justice?
Friendship, gratitude, sympathy, loyalty,
betrayal, guilt, dislike, revenge, trust,
suspicion, dishonesty, hypocrisy
Selfish caller Hypotheses
1. Full up “I see you”
2. Mass pandemonium
3. Keep on moving
4. Mixed species flocks, fake alarm calls
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
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 offere
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/
Evolution of Self Deceit
Subconscious mind
Polygraph playback experiments
Fool Yourself
The Better to Fool Others
Evolution of Self Deceit
Subconscious mind
Polygraph playback experiments
Fool Yourself
The Better to Fool Others
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)
Nudibranchs
Green sea slug
Hydra