ZOO 4070 Lecture Notes - Lecture 11: Sperm Competition, Lek Mating, Ejaculation
2 May 2018
School
Department
Course
Professor
Signals, fighting, and assessment
!
Life-history strategies
!
Precopulatory tactics:
○
Sperm competition
!
Postcopulatory tactics:
○
Can take subtle and not so subtle forms:
•
Will either parallel walk(size it up) or
withdraw
□
Two males approach and have a "roar
contest"
!
If they parallel walk, will either fight or
withdraw
!
Consequence: access to mates
!
Ex. Red deer
○
Male will have multiple female
□
Female rank is largely inherited but
males will fight for dominance rank
□
Correlation between dominance rank and
ability to monopolize fertile females
!
Ex. Olive baboons
○
Signals, fighting and assessment:
•
Selection should favour females that are able to
assess male-male competition
○
Is same sex competition always for access to the opposite
sex?
•
Male-Male Competition:
All purpose territories
!
Socially monogamous
!
1/3 of broods contain extra-pair young
!
Black-capped chickadee:
○
Frequency of males "fee bee" song during dawn
chorus reflects social rank within neighbourhood
○
High ranking -deeper pitch
!
Play back at lower frequency
!
Can also overlap song --> aggressive
playback (vs. submissive)
!
Experiment: interactive playback in the field
○
High-ranking males lose song contests
!
Low-ranking males win song contests
!
Treatments:
○
Test: proportion of extra-pair young in brood
○
Compared to submissive
playback (1/10) and no playback
(1/10)
!
Proportion of nests with extra-pair
young was highest in experimental
aggressive playback (12/23)
□
High ranking males:
!
No increase in extra-pair young
□
Submissive playback (7/17), aggressive
playback (3/6) and no playback (4/10)
□
Low ranking males:
!
Results:
○
Mennill: tested hypothesis that females eavesdrop on
male-male competition to asses male quality
•
Female assessment:
Territorial male
○
Sneaker male --> mixes sperm during copulation
○
Release sperm on eggs
!
Female mimics (satellites) --> try to mimic females
so they wont receive aggression from territorial
male
○
Ex. Bluegill tuna -3 different strategies:
•
Yearling males show delayed plumage with wide
variation
○
Almost all adult males mate
○
Intermediate males do not pair with
females --> bimodal distribution
!
Really dull and really bright yearlings pair as well
○
Dull yearling males tend to settle around
bright coloured adults
!
More brightly coloured yearlings tended to be
further away from adults
!
Looked at spatial distribution of territories
○
May make them look brighter
□
Yearlings could trick males into
thinking they're females?
□
Tend to get more females (adult males
take advantage by siring a lot of extra-
pair young)
□
Adult males let dull yearlings settle around
them
!
Bright yearlings settle farther away from
adults so they look more vibrant to females
!
Two different strategies:
○
Result: have more young than
intermediate males
□
Dull juveniles: adults let them settle in high
quality territories as neighbours
!
Result: sire more total young by
copulating with dull males' female
□
Adults: let dull juveniles settle near them
!
Mutualism among competitiors:
○
Feathers are molted during migration in
southwest US, conditional on environment
!
Fitness estimates between dull and bright
juveniles are not equal
!
Condition strategies in yearlings:
○
Ex. Lazuli buntings
•
Life-history Mating Strategies:
Alternate vs. Conditional Strategies
Alternative Conditional
mechanism Genetic Condition
stability Stable (ESS) Unstable
fitness Equal Equal or Unequal
Males molt before breeding and involve in leking strategy
(set up display sites)
•
Most individuals site zero-little young
!
Leking vs. helper --> major reproductive skew
○
Have alternative morphs (phenotypes)
•
Set up display leks (20%)
○
Floater males (65%)
○
Satellites, share courts with residents (15%)
○
Morphs:
•
SS = independent
!
Ss = satellite
!
*have equal fitness
!
S (satellite is dominant)
○
Traits are Mendelian autosomal:
•
Females prefer to mate on co-occupied courts
○
About equal per capita fitness between morphs
○
Satellite -lower variation in reproductive success
○
How is trait maintained?
•
Genetic based
○
Condition based (poor --> floater)
○
--> mixed strategy (see alternative morphs in Ruffs slide)
•
Ex. Alternative morphs in Ruffs
--> density-dependent fitness
!
As the frequency of morph increases, the fitness
decreases
○
y* > x* --> therefore, females produce
y*
□
As frequency of morph y increases, it is
more beneficial (higher fitness) for
females to produce x*
□
At low frequency of morph y, the fitness of
morph y > x
!
yfis not equal to xf
□
xf= (1-yf) = 1 -0.5 = 0.5
□
Note; frequency does not have to
equal (not always 50%) but
fitness will always be equal
!
--> long-term equilibrium (evolutionary
stable strategy)
□
x* = y*
!
As the frequency of morph y (independent)
increases, the fitness of morph x (satellite) is higher
than y
○
Fitness of one phenotype (morph) is dependent on the
frequency of one or more other phenotypes
•
Alternative Strategies & Frequency-Dependent Selection
Body size and colouring
○
Third morph = cryptic male (looks similar to female) -->
the faeder
•
Hang out near displaying males
○
Diplaying males court faeders
○
Faeders crouch and are mounted by other males
○
The faeder:
•
*determined that all morphs have a genetic basis
•
**a third morph was discovered in the Ruffs
Shaping brain sexuality: proximate mechanisms leading to
alternative reproductive tactics in the plainfin midshipman
Even overt male-male competition does not guarantee
sole access to females
•
Access to oestrus female
○
Mating opportunity
○
Fertilization
○
If individual wins battle, it may lead to:
•
*sperm hitting target = fertilization
•
Therefore, there are intense levels of sexual selection
•
Combat
!
Ex. In mice -multiple sperm hook into
each other to swim (for a higher
velocity)
□
Cooperation
!
Volume
!
Number of sperm increases with
decreasing sperm velocity
!
Fast sperm die quickly
◊
Initial sperm velocity decreases
with sperm age
!
Ex. Sea urchin
□
Mobility
!
Sperm
○
Oestrus only for a few hours after
emergence
□
Copulation is followed by close
guarding to maximize paternity of each
male
□
Ex. Idaho ground squirrel
!
Time spend foraging is decreased with
increased guarding (increases with
number of neighbor males)
□
Limits extra-pair copulations
!
Intrusions go down with guarding (only
when female is fertile)
□
If fake egg is added, male ceases mate
guarding --> susceptive to intrusion
□
Ex. Seychelles warbler
!
Mate guarding
○
Male grasps female's thorax and
scraps other sperm out of
female's reproductive tract using
lateral horns
!
Ex. Black-winged damselfly
□
Sperm removal
!
Not all plugs are permanent -
temperature dependent
!
Ex. Sperm plugs in dungeness crab and
masked palm civets
□
Copulation plug
!
Genital organs
○
Selection Pressure:
•
Acanthocephalan worms males copulate with other
males to seal up their genitals
○
Xylocoris maculipennis males inseminate directly
into the body cavity of both females and males
○
Extreme sperm warfare:
•
Sperm Competition (post-copulation)
Y axis = volume of sperm
•
*see slide
•
Closer to time that eggs are created, males that copulate
later will have a larger volume of sperm, and are more
likely to fertilize eggs
•
Instant (Internal) Fertilization Model:
Following spawning, if three males release sperm there
may be an equal or differential chance of each fertilizing
eggs
•
Continuous (External) Fertilization Model
Sperm plug
○
Mate guarding
○
Sperm removal
○
Internal:
•
Sperm velocity
○
External:
•
Are there adaptive male characteristics associated with each?
Single -passive loss or death over receptive period
•
Multiple -ejaculations are smaller but occur throughout
the receptive period (higher sperm number by end of
receptive period)
•
Single wins at start but multiple is more efficient at
end of oestrus period
○
*if by volume:
•
Length of oestrus period
○
Ability to locate conspecific
○
How much sperm each individual can produce
○
Rate of sperm deterioration
○
Mating systems
○
Factors that influence strategy:
•
Ejaculate strategies should vary according to male
mating strategy
○
Both ejaculate volume and total number of sperm
are higher in parental (vs. sneaker)
○
Sperm tail length and ATP per sperm (energy
levels) is higher in sneaker (vs. parental)
!
--> degree of sperm competition
!
Sneaker adopts multiple ejaculation strategy
○
Therefore, life history strategies of different
phenotypes can result in different copulation
behaviour
○
Ex. Bluegill Tuna
•
Single vs. Multiple Ejaculations
Male-Male Competition &
Alternative Tactics
Monday,*November* 20,*2017
11:37*AM
Signals, fighting, and assessment
!
Life-history strategies
!
Precopulatory tactics:
○
Sperm competition
!
Postcopulatory tactics:
○
Can take subtle and not so subtle forms:
•
Will either parallel walk(size it up) or
withdraw
□
Two males approach and have a "roar
contest"
!
If they parallel walk, will either fight or
withdraw
!
Consequence: access to mates
!
Ex. Red deer
○
Male will have multiple female
□
Female rank is largely inherited but
males will fight for dominance rank
□
Correlation between dominance rank and
ability to monopolize fertile females
!
Ex. Olive baboons
○
Signals, fighting and assessment:
•
Selection should favour females that are able to
assess male-male competition
○
Is same sex competition always for access to the opposite
sex?
•
Male-Male Competition:
All purpose territories
!
Socially monogamous
!
1/3 of broods contain extra-pair young
!
Black-capped chickadee:
○
Frequency of males "fee bee" song during dawn
chorus reflects social rank within neighbourhood
○
High ranking -deeper pitch
!
Play back at lower frequency
!
Can also overlap song --> aggressive
playback (vs. submissive)
!
Experiment: interactive playback in the field
○
High-ranking males lose song contests
!
Low-ranking males win song contests
!
Treatments:
○
Test: proportion of extra-pair young in brood
○
Compared to submissive
playback (1/10) and no playback
(1/10)
!
Proportion of nests with extra-pair
young was highest in experimental
aggressive playback (12/23)
□
High ranking males:
!
No increase in extra-pair young
□
Submissive playback (7/17), aggressive
playback (3/6) and no playback (4/10)
□
Low ranking males:
!
Results:
○
Mennill: tested hypothesis that females eavesdrop on
male-male competition to asses male quality
•
Female assessment:
Territorial male
○
Sneaker male --> mixes sperm during copulation
○
Release sperm on eggs
!
Female mimics (satellites) --> try to mimic females
so they wont receive aggression from territorial
male
○
Ex. Bluegill tuna -3 different strategies:
•
Yearling males show delayed plumage with wide
variation
○
Almost all adult males mate
○
Intermediate males do not pair with
females --> bimodal distribution
!
Really dull and really bright yearlings pair as well
○
Dull yearling males tend to settle around
bright coloured adults
!
More brightly coloured yearlings tended to be
further away from adults
!
Looked at spatial distribution of territories
○
May make them look brighter
□
Yearlings could trick males into
thinking they're females?
□
Tend to get more females (adult males
take advantage by siring a lot of extra-
pair young)
□
Adult males let dull yearlings settle around
them
!
Bright yearlings settle farther away from
adults so they look more vibrant to females
!
Two different strategies:
○
Result: have more young than
intermediate males
□
Dull juveniles: adults let them settle in high
quality territories as neighbours
!
Result: sire more total young by
copulating with dull males' female
□
Adults: let dull juveniles settle near them
!
Mutualism among competitiors:
○
Feathers are molted during migration in
southwest US, conditional on environment
!
Fitness estimates between dull and bright
juveniles are not equal
!
Condition strategies in yearlings:
○
Ex. Lazuli buntings
•
Life-history Mating Strategies:
Alternate vs. Conditional Strategies
Alternative Conditional
mechanism Genetic Condition
stability Stable (ESS) Unstable
fitness Equal Equal or Unequal
Males molt before breeding and involve in leking strategy
(set up display sites)
•
Most individuals site zero-little young
!
Leking vs. helper --> major reproductive skew
○
Have alternative morphs (phenotypes)
•
Set up display leks (20%)
○
Floater males (65%)
○
Satellites, share courts with residents (15%)
○
Morphs:
•
SS = independent
!
Ss = satellite
!
*have equal fitness
!
S (satellite is dominant)
○
Traits are Mendelian autosomal:
•
Females prefer to mate on co-occupied courts
○
About equal per capita fitness between morphs
○
Satellite -lower variation in reproductive success
○
How is trait maintained?
•
Genetic based
○
Condition based (poor --> floater)
○
--> mixed strategy (see alternative morphs in Ruffs slide)
•
Ex. Alternative morphs in Ruffs
--> density-dependent fitness
!
As the frequency of morph increases, the fitness
decreases
○
y* > x* --> therefore, females produce
y*
□
As frequency of morph y increases, it is
more beneficial (higher fitness) for
females to produce x*
□
At low frequency of morph y, the fitness of
morph y > x
!
yfis not equal to xf
□
xf= (1-yf) = 1 -0.5 = 0.5
□
Note; frequency does not have to
equal (not always 50%) but
fitness will always be equal
!
--> long-term equilibrium (evolutionary
stable strategy)
□
x* = y*
!
As the frequency of morph y (independent)
increases, the fitness of morph x (satellite) is higher
than y
○
Fitness of one phenotype (morph) is dependent on the
frequency of one or more other phenotypes
•
Alternative Strategies & Frequency-Dependent Selection
Body size and colouring
○
Third morph = cryptic male (looks similar to female) -->
the faeder
•
Hang out near displaying males
○
Diplaying males court faeders
○
Faeders crouch and are mounted by other males
○
The faeder:
•
*determined that all morphs have a genetic basis
•
**a third morph was discovered in the Ruffs
Shaping brain sexuality: proximate mechanisms leading to
alternative reproductive tactics in the plainfin midshipman
Even overt male-male competition does not guarantee
sole access to females
•
Access to oestrus female
○
Mating opportunity
○
Fertilization
○
If individual wins battle, it may lead to:
•
*sperm hitting target = fertilization
•
Therefore, there are intense levels of sexual selection
•
Combat
!
Ex. In mice -multiple sperm hook into
each other to swim (for a higher
velocity)
□
Cooperation
!
Volume
!
Number of sperm increases with
decreasing sperm velocity
!
Fast sperm die quickly
◊
Initial sperm velocity decreases
with sperm age
!
Ex. Sea urchin
□
Mobility
!
Sperm
○
Oestrus only for a few hours after
emergence
□
Copulation is followed by close
guarding to maximize paternity of each
male
□
Ex. Idaho ground squirrel
!
Time spend foraging is decreased with
increased guarding (increases with
number of neighbor males)
□
Limits extra-pair copulations
!
Intrusions go down with guarding (only
when female is fertile)
□
If fake egg is added, male ceases mate
guarding --> susceptive to intrusion
□
Ex. Seychelles warbler
!
Mate guarding
○
Male grasps female's thorax and
scraps other sperm out of
female's reproductive tract using
lateral horns
!
Ex. Black-winged damselfly
□
Sperm removal
!
Not all plugs are permanent -
temperature dependent
!
Ex. Sperm plugs in dungeness crab and
masked palm civets
□
Copulation plug
!
Genital organs
○
Selection Pressure:
•
Acanthocephalan worms males copulate with other
males to seal up their genitals
○
Xylocoris maculipennis males inseminate directly
into the body cavity of both females and males
○
Extreme sperm warfare:
•
Sperm Competition (post-copulation)
Y axis = volume of sperm
•
*see slide
•
Closer to time that eggs are created, males that copulate
later will have a larger volume of sperm, and are more
likely to fertilize eggs
•
Instant (Internal) Fertilization Model:
Following spawning, if three males release sperm there
may be an equal or differential chance of each fertilizing
eggs
•
Continuous (External) Fertilization Model
Sperm plug
○
Mate guarding
○
Sperm removal
○
Internal:
•
Sperm velocity
○
External:
•
Are there adaptive male characteristics associated with each?
Single -passive loss or death over receptive period
•
Multiple -ejaculations are smaller but occur throughout
the receptive period (higher sperm number by end of
receptive period)
•
Single wins at start but multiple is more efficient at
end of oestrus period
○
*if by volume:
•
Length of oestrus period
○
Ability to locate conspecific
○
How much sperm each individual can produce
○
Rate of sperm deterioration
○
Mating systems
○
Factors that influence strategy:
•
Ejaculate strategies should vary according to male
mating strategy
○
Both ejaculate volume and total number of sperm
are higher in parental (vs. sneaker)
○
Sperm tail length and ATP per sperm (energy
levels) is higher in sneaker (vs. parental)
!
--> degree of sperm competition
!
Sneaker adopts multiple ejaculation strategy
○
Therefore, life history strategies of different
phenotypes can result in different copulation
behaviour
○
Ex. Bluegill Tuna
•
Single vs. Multiple Ejaculations
Male-Male Competition &
Alternative Tactics
Monday,*November* 20,*2017 11:37*AM
Signals, fighting, and assessment
!
Life-history strategies
!
Precopulatory tactics:
○
Sperm competition
!
Postcopulatory tactics:
○
Can take subtle and not so subtle forms:
•
Will either parallel walk(size it up) or
withdraw
□
Two males approach and have a "roar
contest"
!
If they parallel walk, will either fight or
withdraw
!
Consequence: access to mates
!
Ex. Red deer
○
Male will have multiple female
□
Female rank is largely inherited but
males will fight for dominance rank
□
Correlation between dominance rank and
ability to monopolize fertile females
!
Ex. Olive baboons
○
Signals, fighting and assessment:
•
Selection should favour females that are able to
assess male-male competition
○
Is same sex competition always for access to the opposite
sex?
•
Male-Male Competition:
All purpose territories
!
Socially monogamous
!
1/3 of broods contain extra-pair young
!
Black-capped chickadee:
○
Frequency of males "fee bee" song during dawn
chorus reflects social rank within neighbourhood
○
High ranking -deeper pitch
!
Play back at lower frequency
!
Can also overlap song --> aggressive
playback (vs. submissive)
!
Experiment: interactive playback in the field
○
High-ranking males lose song contests
!
Low-ranking males win song contests
!
Treatments:
○
Test: proportion of extra-pair young in brood
○
Compared to submissive
playback (1/10) and no playback
(1/10)
!
Proportion of nests with extra-pair
young was highest in experimental
aggressive playback (12/23)
□
High ranking males:
!
No increase in extra-pair young
□
Submissive playback (7/17), aggressive
playback (3/6) and no playback (4/10)
□
Low ranking males:
!
Results:
○
Mennill: tested hypothesis that females eavesdrop on
male-male competition to asses male quality
•
Female assessment:
Territorial male
○
Sneaker male --> mixes sperm during copulation
○
Release sperm on eggs
!
Female mimics (satellites) --> try to mimic females
so they wont receive aggression from territorial
male
○
Ex. Bluegill tuna -3 different strategies:
•
Yearling males show delayed plumage with wide
variation
○
Almost all adult males mate
○
Intermediate males do not pair with
females --> bimodal distribution
!
Really dull and really bright yearlings pair as well
○
Dull yearling males tend to settle around
bright coloured adults
!
More brightly coloured yearlings tended to be
further away from adults
!
Looked at spatial distribution of territories
○
May make them look brighter
□
Yearlings could trick males into
thinking they're females?
□
Tend to get more females (adult males
take advantage by siring a lot of extra-
pair young)
□
Adult males let dull yearlings settle around
them
!
Bright yearlings settle farther away from
adults so they look more vibrant to females
!
Two different strategies:
○
Result: have more young than
intermediate males
□
Dull juveniles: adults let them settle in high
quality territories as neighbours
!
Result: sire more total young by
copulating with dull males' female
□
Adults: let dull juveniles settle near them
!
Mutualism among competitiors:
○
Feathers are molted during migration in
southwest US, conditional on environment
!
Fitness estimates between dull and bright
juveniles are not equal
!
Condition strategies in yearlings:
○
Ex. Lazuli buntings
•
Life-history Mating Strategies:
Alternate vs. Conditional Strategies
Alternative Conditional
mechanism Genetic Condition
stability Stable (ESS) Unstable
fitness Equal Equal or Unequal
Males molt before breeding and involve in leking strategy
(set up display sites)
•
Most individuals site zero-little young
!
Leking vs. helper --> major reproductive skew
○
Have alternative morphs (phenotypes)
•
Set up display leks (20%)
○
Floater males (65%)
○
Satellites, share courts with residents (15%)
○
Morphs:
•
SS = independent
!
Ss = satellite
!
*have equal fitness
!
S (satellite is dominant)
○
Traits are Mendelian autosomal:
•
Females prefer to mate on co-occupied courts
○
About equal per capita fitness between morphs
○
Satellite -lower variation in reproductive success
○
How is trait maintained?
•
Genetic based
○
Condition based (poor --> floater)
○
--> mixed strategy (see alternative morphs in Ruffs slide)
•
Ex. Alternative morphs in Ruffs
--> density-dependent fitness
!
As the frequency of morph increases, the fitness
decreases
○
y* > x* --> therefore, females produce
y*
□
As frequency of morph y increases, it is
more beneficial (higher fitness) for
females to produce x*
□
At low frequency of morph y, the fitness of
morph y > x
!
yfis not equal to xf
□
xf= (1-yf) = 1 -0.5 = 0.5
□
Note; frequency does not have to
equal (not always 50%) but
fitness will always be equal
!
--> long-term equilibrium (evolutionary
stable strategy)
□
x* = y*
!
As the frequency of morph y (independent)
increases, the fitness of morph x (satellite) is higher
than y
○
Fitness of one phenotype (morph) is dependent on the
frequency of one or more other phenotypes
•
Alternative Strategies & Frequency-Dependent Selection
Body size and colouring
○
Third morph = cryptic male (looks similar to female) -->
the faeder
•
Hang out near displaying males
○
Diplaying males court faeders
○
Faeders crouch and are mounted by other males
○
The faeder:
•
*determined that all morphs have a genetic basis
•
**a third morph was discovered in the Ruffs
Shaping brain sexuality: proximate mechanisms leading to
alternative reproductive tactics in the plainfin midshipman
Even overt male-male competition does not guarantee
sole access to females
•
Access to oestrus female
○
Mating opportunity
○
Fertilization
○
If individual wins battle, it may lead to:
•
*sperm hitting target = fertilization
•
Therefore, there are intense levels of sexual selection
•
Combat
!
Ex. In mice -multiple sperm hook into
each other to swim (for a higher
velocity)
□
Cooperation
!
Volume
!
Number of sperm increases with
decreasing sperm velocity
!
Fast sperm die quickly
◊
Initial sperm velocity decreases
with sperm age
!
Ex. Sea urchin
□
Mobility
!
Sperm
○
Oestrus only for a few hours after
emergence
□
Copulation is followed by close
guarding to maximize paternity of each
male
□
Ex. Idaho ground squirrel
!
Time spend foraging is decreased with
increased guarding (increases with
number of neighbor males)
□
Limits extra-pair copulations
!
Intrusions go down with guarding (only
when female is fertile)
□
If fake egg is added, male ceases mate
guarding --> susceptive to intrusion
□
Ex. Seychelles warbler
!
Mate guarding
○
Male grasps female's thorax and
scraps other sperm out of
female's reproductive tract using
lateral horns
!
Ex. Black-winged damselfly
□
Sperm removal
!
Not all plugs are permanent -
temperature dependent
!
Ex. Sperm plugs in dungeness crab and
masked palm civets
□
Copulation plug
!
Genital organs
○
Selection Pressure:
•
Acanthocephalan worms males copulate with other
males to seal up their genitals
○
Xylocoris maculipennis males inseminate directly
into the body cavity of both females and males
○
Extreme sperm warfare:
•
Sperm Competition (post-copulation)
Y axis = volume of sperm
•
*see slide
•
Closer to time that eggs are created, males that copulate
later will have a larger volume of sperm, and are more
likely to fertilize eggs
•
Instant (Internal) Fertilization Model:
Following spawning, if three males release sperm there
may be an equal or differential chance of each fertilizing
eggs
•
Continuous (External) Fertilization Model
Sperm plug
○
Mate guarding
○
Sperm removal
○
Internal:
•
Sperm velocity
○
External:
•
Are there adaptive male characteristics associated with each?
Single -passive loss or death over receptive period
•
Multiple -ejaculations are smaller but occur throughout
the receptive period (higher sperm number by end of
receptive period)
•
Single wins at start but multiple is more efficient at
end of oestrus period
○
*if by volume:
•
Length of oestrus period
○
Ability to locate conspecific
○
How much sperm each individual can produce
○
Rate of sperm deterioration
○
Mating systems
○
Factors that influence strategy:
•
Ejaculate strategies should vary according to male
mating strategy
○
Both ejaculate volume and total number of sperm
are higher in parental (vs. sneaker)
○
Sperm tail length and ATP per sperm (energy
levels) is higher in sneaker (vs. parental)
!
--> degree of sperm competition
!
Sneaker adopts multiple ejaculation strategy
○
Therefore, life history strategies of different
phenotypes can result in different copulation
behaviour
○
Ex. Bluegill Tuna
•
Single vs. Multiple Ejaculations
Male-Male Competition &
Alternative Tactics
Monday,*November* 20,*2017 11:37*AM
