VI. Levels of Selection

1
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection 1.
Meiotic Drive

• - Stalk-eyed flies, Cyrtodiopsis dalmanni and C.
  whitei (Presgraves, et al.1997).
• X(d) meiotic drive element on the X chromosome
  causes female-biased sex ratios
• spermatid degeneration of Y-bearing sperm in
  male carriers of X(d).
• balanced by Y-linked and autosomal factors that
  decrease the intensity of meiotic drive.
• Even a Y-linked polymorphism for resistance to
  drive which reduces the intensity and reverses
  the direction of meiotic drive.
• When paired with X(d), modifying Y chromosomes
  (Y(m)) cause the transmission of predominantly
  Y-bearing sperm, and on average, production of
  63 male progeny.

2
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection 1.
Meiotic Drive 2. Transposable Elements
3
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection 1.
Meiotic Drive 2. Transposable Elements these
genes replicate themselves independently of cell
division... they are gene parasites that make
nothing for the cell. yet they increase in
frequency relative to other genes in the genome.
4
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection 1.
Meiotic Drive 2. Transposable Elements 3.
'Selfish' Genes (Richard Dawkins)
5
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection 1.
Meiotic Drive 2. Transposable Elements 3.
'Selfish' Genes (Richard Dawkins) - genes are
the fundamental replicators
6
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection 1.
Meiotic Drive 2. Transposable Elements 3.
'Selfish' Genes (Richard Dawkins) - genes are
the fundamental replicators - genes which
confer an advantage, when averaged across other
genetic backgrounds, will be selected for.
(Analogy of 'crews')
7
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection 1.
Meiotic Drive 2. Transposable Elements 3.
'Selfish' Genes (Richard Dawkins) - genes are
the fundamental replicators - genes which
confer an advantage, when averaged across other
genetic backgrounds, will be selected for.
Analogy of 'crews') - co-adaptive assemblages
and non-additive effects are not explained
8
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection
9
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection - some mitochondria in
yeast are non-respiring parasites - they survive
but don't produce much energy for the cell. They
reproduce fast in a cell.
10
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection - some mitochondria in
yeast are non-respiring parasites - they survive
but don't produce much energy for the cell. They
reproduce fast in a cell. - In small populations
of yeast, where selection at the organismal level
is weak, there is no cost to the cell to
reproducing slowly and the parasitic mitochondria
dominate within cells.
11
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection - some mitochondria in
yeast are non-respiring parasites - they survive
but don't produce much energy for the cell. They
reproduce fast in a cell. - In small populations
of yeast, where selection at the organismal level
is weak, there is no cost to the cell to
reproducing slowly and the parasitic mitochondria
dominate within cells. - In large populations,
where aerobic respiration is advantageous at a
cellular level, cells with parasites are selected
against and the frequency of parasitic
mitochondria is reduced.
12
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection - some mitochondria in
yeast are non-respiring parasites - they survive
but don't produce much energy for the cell. They
reproduce fast in a cell. - In small populations
of yeast, where selection at the organismal level
is weak, there is no cost to the cell to
reproducing slowly and the parasitic mitochondria
dominate within cells. - In large populations,
where aerobic respiration is advantageous at a
cellular level, cells with parasites are selected
against and the frequency of parasitic
mitochondria is reduced. - There is a balance of
selection at different levels that must be
understood to explain the different frequency of
parasitic mitochondria.
13
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection C. Cell Selection
14
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection C. Cell Selection -
Cancerous Tumour - cell division increases, and
the effects may be balanced at a higher level
(organism).
15
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection C. Cell Selection D.
Organism Selection (Darwinian)
16
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection C. Cell Selection D.
Organism Selection (Darwinian) E. Kin
Selection
17

1. Darwins Dilemma
bees make me sad
18
2. W. D. Hamilton - 1964 - related individuals
that help one another increase their OWN fitness,
because their alleles occur within THOSE
relatives.
19
2. W. D. Hamilton - 1964 - related individuals
that help one another increase their OWN fitness,
because their alleles occur within THOSE
relatives. a. Inclusive Fitness
several relatives have more of YOUR genes,
cumulatively, than YOU do! ½ ½ ½ gt 1
1/2
1/2
1/2
1
20
a. Inclusive Fitness
1/2
1/2
1/2
1
21
If I save myself
AAAAAAAAA !!!!!
X
X
X
X
X
I save one set of my genes
X
1/2
1/2
1
1/2
1
22
If I save my relatives I save 1.5 sets of my
genes. If this has a genetic basis, selection
will favor altruism among relatives.
What a guy!
ow
1/2
1/2
1/2
1/2
1/2
1/2
1
23
3. Examples 1. Helping among relatives a
function of kin selection
24
3. Examples 1. Helping among relatives a
function of kin selection
25
3. Examples 1. Helping among relatives a
function of kin selection
26
3. Examples 2. Haplodiploidy and Social
Insects
W. D. Hamilton 1964
bees make me sad
rb gt c
27
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection C. Cell Selection D.
Organism Selection (Darwinian) E. Kin
Selection F. Group Selection (Wynne-Edwards)
28
F. Group Selection (Wynne-Edwards) - Can groups
replace one another simply by reproductive
success??
29
F. Group Selection (Wynne-Edwards) - Can groups
replace one another simply by reproductive
success?? - First, it would have to be
recognized by it's contradiction with organismal
selection.
30
F. Group Selection (Wynne-Edwards) - Can groups
replace one another simply by reproductive
success?? - First, it would have to be
recognized by it's contradiction with organismal
selection. - (Sacrifice of fitness at the
organismal level with increase at the level of
the group).
31
F. Group Selection (Wynne-Edwards) - Can groups
replace one another simply by reproductive
success?? - First, it would have to be
recognized by it's contradiction with organismal
selection. - (Sacrifice of fitness at the
organismal level with increase at the level of
the group). - Altruism is a possible example -
sacrifice reproduction for benefit of the
group... but it usually doesn't work because
f(altruism) declines within the pop if organisms
are unrelated!
32
F. Group Selection (Wynne-Edwards) - But
there are caveats with kin selection, too

• Naked mole-rats
• Live for 31 years
• Dont get cancer division inhibited by cell-cell
  contact, and have an odd hyaluronan protein5x
  larger than humans and cancer-prone species in
  which the normal form increases rate of
  metastasis.
• MUCH lower mutation rate
• Only mammals that are thermoconformers
• Eusocial one queen, 2-3 males, the rest
  sterile workers in two size castes.
• Vertebrate of the Year in 2013

33
Problem To show group selection, distinct from
individual selection, it must be shown that a net
cost to the individual is outweighed by a net
benefit to the group, without invoking
relatedness and kin selection. This is different
than an individual benefiting MORE by helping the
group than by acting selfishly. THIS is still
maximizing individual fitness. PRO GROUP
Wilson ANTI GROUP Pinker
34
VI. Levels of Selection Selection can occur
wherever there is differential reproduction among
variable entities. A. Gene Selection B.
Organelle Selection C. Cell Selection D.
Organism Selection (Darwinian) E. Kin
Selection F. Group Selection (Wynne-Edwards)
G. Species Selection
35
G. Species Selection
36
G. Species Selection - Selection for sexually
reproducing species Parthenogenesis arises
spontaneously, but extinctions are rapid due to
lack of variation and Muller's rachet.
Muller's ratchet is the continuous
accumulation of mutations in a lineage. In
sexual reproduction, since only 1/2 of the genes
are passed from each parent, there is a 50
chance that a deleterious new mutation will be
purged from the genome just by chance. And also,
even if it is expressed, there will be other
organisms in the pop that did NOT receive it and
have higher fitness. So, selection can purify
this sexual population of the deleterious
alleles. But in an asexual lineage, all offspring
get the whole genome - even a new deleterious
allele. So, there is no way to purge it from the
genome. In fact, in Daphnia pulex, asexual
lineages accumulate deleterious amino acid
substitutions at 4x the rate of sexual lineages
(Paland and Lynch 2006, Science 311990-992).
37
G. Species Selection - Selection for sexually
reproducing species - Parthenogenesis arises
spontaneously, but extinctions are rapid due to
lack of variation and Muller's rachet. So,
extinction rates in parthenogenetic lineages are
high... and so most lineages that radiate and
produce lots of descendant species are sexual.
38
G. Species Selection - Selection for sexually
reproducing species - Certain lineage are more
likely to speciate (beetles - small, tough, and
easily isolated...)
39
G. Species Selection - Selection for sexually
reproducing species - Certain lineage are more
likely to speciate (beetles - small, tough, and
easily isolated...) SO, as a consequence of
survival and speciation rate (reproduction),
sexual lineages and also more rapidly speciating
lineages will leave more species and replace
other lineages that die out over time.
40
Sexual Selection - Recognized as a deviation
from predictions offered by a strict selection
model. In this case, there are different
selective pressures on each SEX.
41
Sexual Selection - Recognized as a deviation
from predictions offered by a strict selection
model. 1. The Basics
42
Sexual Selection 1. The Basics - many species
show sexual dimorphism (morph or behav)
43
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics - many species show sexual
dimorphism (morph or behav) - WHY? If adaptive
(must be tested), then selective pressures
differ
44
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics - many species show sexual
dimorphism (morph or behav) - WHY? If adaptive
(must be tested), then selective pressures
differ - Some traits appear COSTLY to survival.
Darwin (1871) described how showy plumage in
birds should decrease survival. In order for it
to be ADAPTIVE (increase reproductive success),
this COST must be OFFSET by a disproportionate
increase in one of the other components of
fitness - most likely NUMBER of offspring.
45
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics - many species show sexual
dimorphism (morph or behav) - WHY? If adaptive
(must be tested), then selective pressures
differ - Some traits appear COSTLY to survival.
Darwin (1871) described how showy plumage in
birds should decrease survival. In order for it
to be ADAPTIVE (increase reproductive success),
this COST must be OFFSET by a disproportionate
increase in one of the other components of
fitness - most likely NUMBER of offspring. -
This is affected by access to mates, number of
mates, number of offspring, and quality of
offspring.
46
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics - many species show sexual
dimorphism (morph or behav) - WHY? If adaptive
(must be tested), then selective pressures
differ - Some traits appear COSTLY to survival.
Darwin (1871) described how showy plumage in
birds should decrease survival. In order for it
to be ADAPTIVE (increase reproductive success),
this COST must be OFFSET by a disproportionate
increase in one of the other components of
fitness - most likely NUMBER of offspring. -
This is affected by access to mates, number of
mates, number of offspring, and quality of
offspring. - These diffs have to vary BETWEEN
SEXES to account for dimorphism... so access to
mates must vary, etc.
47
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics - many species show sexual
dimorphism (morph or behav) - WHY? If adaptive
(must be tested), then selective pressures
differ - Some traits appear COSTLY to survival.
Darwin (1871) described how showy plumage in
birds should decrease survival. In order for it
to be ADAPTIVE (increase reproductive success),
this COST must be OFFSET by a disproportionate
increase in one of the other components of
fitness - most likely NUMBER of offspring. -
This is affected by access to mates, number of
mates, number of offspring, and quality of
offspring. - These diffs have to vary BETWEEN
SEXES to account for dimorphism... so access to
mates must vary, etc. - Darwin (1871) though of
two patterns
48
- Darwin (1871) though of two patterns Male
Contest Female Choice
49
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972)
50
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) - what
is a fundamental difference between most sexes?
gamete size
51
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) - what
is a fundamental difference between most sexes?
gamete size - in anisogamous species (different
sized gametes), the female produces a few large
gametes, and the male produces lots of small
ones.
52
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) - what
is a fundamental difference between most sexes?
gamete size - in anisogamous species (different
sized gametes), the female produces a few large
gametes, and the male produces lots of small
ones. - Thus, the female invests more energy in
each gamete, and that may be the tip of the
iceberg (fruit, seed, yolk, uterine development,
care...)
53
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) - what
is a fundamental difference between most sexes?
gamete size - in anisogamous species (different
sized gametes), the female produces a few large
gametes, and the male produces lots of small
ones. - Thus, the female invests more energy in
each gamete, and that may be the tip of the
iceberg (fruit, seed, yolk, uterine development,
care...) - So Female success is limited by
number of offspring she can make Male
success is limited by access to/number of mates
54
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) - what
is a fundamental difference between most sexes?
gamete size - in anisogamous species (different
sized gametes), the female produces a few large
gametes, and the male produces lots of small
ones. - Thus, the female invests more energy in
each gamete, and that may be the tip of the
iceberg (fruit, seed, yolk, uterine development,
care...) - So Female success is limited by
number of offspring she can raise Male
success is limited by access to/number of
mates - There should be greater VARIANCE among
males in success, so selection for mate
acquisition should be stronger in males.
55
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) C.
Tests (Jones 2002) - Newts offspring
correlates with number of mates in males, not
females
male
offspring
female
mates
56
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) 3.
Tests (Jones 2002) - Pipefish where males
incubate young, the pattern is reversed...
female
offspring
male
mates
57
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) 3.
Tests (Jones 2002) - Pipefish where males
incubate young, the pattern is reversed...
- SO reproductive strategy correlates better
with INVESTMENT than SEX, per se.
female
offspring
male
mates
58
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) 3.
Tests (Jones 2002) 4. Conclusions
59
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) 3.
Tests (Jones 2002) 4. Conclusions - Darwin
and Bateman said males are competitive, and the
only recourse left to females is to be choosy.
60
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) 3.
Tests (Jones 2002) 4. Conclusions - Darwin
and Bateman said males are competitive, and the
only recourse left to females is to be choosy. -
Things are more complex (pipefish, monogamy)
61
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) 3.
Tests (Jones 2002) 4. Conclusions - Darwin
and Bateman said males are competitive, and the
only recourse left to females is to be choosy. -
Things are more complex (pipefish, monogamy) -
If one sex is limited by access, that sex should
compete.
62
Sexual Selection - not really a level, but
recognized in the same way - as a deviation from
predictions offered by a strict selection model.
1. The Basics 2. Hypothesis of Parental
Investment (Bateman 1948, Trivers 1972) 3.
Tests (Jones 2002) 4. Conclusions - Darwin
and Bateman said males are competitive, and the
only recourse left to females is to be choosy. -
Things are more complex (pipefish, monogamy) -
If one sex is limited by access, that sex should
compete. - The sex NOT limited by access can
then be choosey and select mates of the highest
QUALITY.
63

• Sexual Selection
• 5. INTRAsexual Competition (for access)

64

• Sexual Selection
• 5. INTRAsexual Competition (for access)
• - competition for harems, territories

65
Sexual Selection 5. INTRAsexual Competition
(for access) - competition for harems,
territories - sperm competition
66
Sexual Selection 5. INTRAsexual Competition
(for access) - competition for harems,
territories - sperm competition - infanticide
67
Sexual Selection 5. INTRAsexual Competition
(for access) - competition for harems,
territories - sperm competition -
infanticide - female mimicry in male subadults
and "stealth matings"
68
"sneaker males"
FEMALE
"Sneaker" male
This and other examples
69
Sexual Selection 6. INTERsexual Selection
(Mate Preference) - A behavior or morphology
that is only performed during the reproductive
season, which increases risk and must then be
offset by mating
70
Sexual Selection 6. INTERsexual Selection
(Mate Preference) - A behavior or morphology
that is only performed during the reproductive
season, which increases risk and must then be
offset by mating showy breeding plumage calling
displays
71
Sexual Selection 6. INTERsexual Selection
(Mate Preference) - A behavior or morphology
that is only performed during the reproductive
season, which increases risk and must then be
offset by mating - WHY is it ADAPTIVE for the
FEMALE to choose a SHOWY MALE??
72
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit - healthy males are
better fathers - the redder the male house finch,
the healthier it is, and the more food it brings
to the nest.
73
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit - Scorpion fly
males bring a 'nuptual gift'... the one with the
biggest gift is accepted by the female (who gets
this extra energy to make eggs).
74
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit - Redback spiders -
males that give themselves up as meal leave more
offspring than those that don't
75
Male mantids eaten during copulation mate longer
and transfer more sperm, and females lay more
eggs.
76
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Good Genes" "GOOD GENES" - Bright
Plumage means low parasite load - Resistance
to parasites has a genetic component - Bright
Males - low parasites - offspring with low
parasites - increased probability of survival.
77
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Good Genes" and Symmetry Theory" "GOOD
GENES" "SYMMETRY THEORY" - many
organisms prefer the most symmetrical mates -
this might indicate co-adapted gene complexes
that work well together during
development. - Moeller demonstrated that
offspring of symmetrical males molt earlier and
develop sooner than offspring of other males.
78
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Good Genes" and Symmetry Theory" "GOOD
GENES" "SYMMETRY THEORY" - many
organisms prefer the most symmetrical mates -
this might indicate co-adapted gene complexes
that work well together during
development. - Moeller demonstrated that
offspring of symmetrical males molt earlier and
develop sooner than offspring of other
males. - And many human studies reveal the
same things - preference for symmetrical
mates
79
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Good Genes" "GOOD GENES"
"SYMMETRY THEORY" - many organisms prefer the
most symmetrical mates - this might indicate
co-adapted gene complexes that work well
together during development
Hmmm....
80
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Good Genes" "GOOD GENES"
"SYMMETRY THEORY" - many organisms prefer the
most symmetrical mates - this might indicate
co-adapted gene complexes that work well
together during development
Hmmm....
81
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Good Genes" "GOOD GENES"
"SYMMETRY THEORY" - many organisms prefer the
most symmetrical mates - this might indicate
co-adapted gene complexes that work well
together during development
Hmmm....
Hey, It Works!!
82
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Handicap Theory" - I'm alive, even WITH
this HUGE TAIL!!! - I must be awesome!!
83
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Runaway Selection" - Positive Feedback
Loops
84
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Runaway Selection" - Positive Feedback
Loops If long tails are attractive to females
for WHATEVER REASON, and they are heritable, then
Females should continue to prefer males with long
tails, because THEIR SONS will then have long
tails and will mate.
85
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Runaway Selection" - Positive Feedback
Loops If long tails are attractive to most
females for WHATEVER REASON, and they are
heritable, then selection will reinforce this
preference because females who select long-tailed
males will produce sons with long tails, who will
be preferred in the next generation and
daughters with a preference for long tails.
86
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Runaway Selection" - Positive Feedback
Loops If long tails are attractive to females
for WHATEVER REASON, and they are heritable, then
Females should continue to prefer males with long
tails, because THEIR SONS will then have long
tails and will mate. Likewise, a female should
produce daughters that are attracted to long
tails, so that their grandsons will have long
tails. May result in SUPERNORMAL STIMULUS - if
a long tail is good, a really long tail is
GREAT!!!
87
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Runaway Selection" - Positive Feedback
Loops If long tails are attractive to females
for WHATEVER REASON, and they are heritable, then
Females should continue to prefer males with long
tails, because THEIR SONS will then have long
tails and will mate. Likewise, a female should
produce daughters that are attracted to long
tails, so that their grandsons will have long
tails. May result in SUPERNORMAL STIMULUS - if
a long tail is good, a really long tail is
GREAT!!! Why hasn't female choice driven male
tail length to that extreme?
88
6. INTERsexual Selection (Mate Preference) - A
behavior or morphology that is only performed
during the reproductive season, which increases
risk and must then be offset by mating - WHY is
it ADAPTIVE for the FEMALE to choose a SHOWY
MALE?? 1. Direct Benefit 2. Indirect Benefit
- "Runaway Selection" - Positive Feedback
Loops If long tails are attractive to females
for WHATEVER REASON, and they are heritable, then
Females should continue to prefer males with long
tails, because THEIR SONS will then have long
tails and will mate. Likewise, a female should
produce daughters that are attracted to long
tails, so that their grandsons will have long
tails. May result in SUPERNORMAL STIMULUS - if
a long tail is good, a really long tail is
GREAT!!! (see long-tailed widowbird example in
book). Why hasn't female choice driven male tail
length to that extreme? CONSTRAINTS (genetic) and
CONTRADICTORY SELECTIVE PRESSURES (energetic,
survival, etc.)