Presented by Mitch Daniel at Evolution 2013

1. Discussion
Visual familiarity
alone was sufficient
to reduce sexual
interest
o Indicates importance of visual cues to novel/
unfamiliar mate preference in this species.
Our results link manipulated DA with some
altered mating behaviours
o Suggests DA may regulate sexual interest.
Novelty and MPH interacted in males
o Consistent with explanation that DA may play a
role in regulating mate preference for novel
individuals.
Future Research
• The risk of inbreeding varies across guppy populations, so
selection on preference for unfamiliar/novel mates may
also vary.
o How does this preference relate to the robust female
preference for males with rare/novel colour patterns (‘rare
male effect’) in the guppy9?
o Can selection act directly on these mating preferences?
o Or (see poster by A. De Serrano & H. Rodd), are these
preferences linked to a suite of other novelty preferences
(e.g. novel objects, novel environments) under selection by
other environmental factors (e.g. predation10)? Are all of
these responses to novelty regulated by dopamine and
thus unlikely to evolve independently?
1
2
3
Results
Behaviour
Descrip/ons7,8
Aggression
Aggressive
behaviours
directed
at
the
male
Approach
Female
moves
towards
the
male,
signaling
recep8vity
Orient
Female
angles
herself
to
face
the
male,
signaling
recep8vity
Female
ini8a8on
Female
first
to
approach
male,
not
vice
versa
Luring
Oriented
towards
female,
male
alternates
between
forward
and
backward
mo8on
Nipping
Male
nibbles
near
female’s
gonopore
Posturing
Male
posi8ons
himself
in
front
of
female,
perpendicular
to
her
field
of
view
Background
• As in a broad range of taxa1, Trinidadian guppies
(Poecilia reticulata) prefer unfamiliar/novel mates2; this
may reduce the risk of inbreeding.
• The neurotransmitter dopamine (DA) is associated with:
o Novelty seeking (the willingness to investigate novel
stimuli), including novel individuals3
o Sexual behaviour in mammals, including rodents and
humans4,5
• DA was manipulated to:
o Determine if this mechanism regulates responsiveness
to familiar vs. novel mates
o Put this preference in the context of (a) other responses
to novelty (see poster by A. De Serrano & H. Rodd), and
(b) selective environments in the wild.
We asked:
Is visual familiarity alone sufficient to reduce
sexual responsiveness?
Does long-term dopamine manipulation alter
mating behaviour in guppies?
If so, do the effects of dopamine interact with
the novelty status of an individual in a mating
context?
Methods
• Guppies (from one population of Houde’s Paria Trib.) were given a
low, chronic dose (2.5*10-8g/mL) of methylphenidate hydrochloride
(MPH (Ritalin®)), a stimulant known to increase dopamine levels6, 3x
per week from 1 mo. old until tested.
• Familiarity was established by rearing individuals in adjacent tanks,
allowing for visual interactions.
• We conducted mating trials with a 2 x 2 x 2 design, in which: (i) pairs
were familiar (n = 45) or novel (n = 63), (ii) males were MPH (n = 55)
or control (n = 53), and (iii) females were MPH (n = 52) or control (n
= 56).
• For each trial, the mating behaviour of a single pair was observed
(tank: 20cm x 40cm with water 14 cm deep) until cooperative mating
occurred, or was stopped after 2 h if mating did not occur.
The effects of familiarity and altered dopamine on mating behaviours
in the guppy
Mitchel Daniel, Alex De Serrano & F. Helen Rodd
Dept. of Ecology and Evolutionary Biology, University of Toronto
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Familiar
Novel
MPH
Control
MPH
Control
Familiarity
Male
Drug
Treatment
Female
Drug
Treatment
Propor/on
o
f
t
rials
No
Circling
Circling
*
Figure 2. Proportion of trials where the fish circled (a proxy for
cooperative mating) for (i) familiar vs. novel mates, (ii) male MPH or
control, and (iii) female MPH or control. Familiarity significantly
reduced the likelihood of circling (replicated G test, heterogeneity G =
5.25, P = 0.022). Male MPH treatment tended to reduce circling
(hetero G = 3.82, P = 0.051). Female drug treatment did not have a
significant effect (hetero G = 0.395, P = 0.530).
Effects of familiarity and drug treatment on circling
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Familiar
Novel
Familiar
Novel
Familiar
Novel
Sigmoid
Displays
Glide
Responses
Sneak
Ma8ng
AWempts
Propor/on
o
f
t
rials
High
Medium
Low
*
Effects of familiarity on three components of mating
behaviour
Figure 1. Proportion of trials with high, medium or low amounts
(count ÷ trial length) of male courtship (sigmoid displays), female
glide responses to male (indicating receptivity), and male sneak
mating attempts, for familiar and novel pairs. Familiarity
significantly reduced female glide responses (replicated G test,
heterogeneity G = 7.43, P = 0.024), but did not significantly affect
sigmoid displays (hetero G = 2.63, P = 0.26) or sneak matings
(hetero G = 0.286, P = 0.867).
Table 1. Familiarity significantly reduced levels
of the following behaviours (all P < 0.05).
Female
Male
0
10
20
30
40
50
60
70
80
Familiar
Novel
Propor/on
o
f
/
me
m
ale
s
pent
f
ollowing
the
f
emale
Male
control
Male
MPH
Male following female
Figure 3. Mean ranked proportion of time male spent following
the female for familiar vs. novel and male MPH vs. control. There
was a significant interaction between familiarity and male
drug treatment (ANOVA, F7,107 = 7.47, P = 0.007); MPH males
were more likely to follow familiar females and less likely to follow
unfamiliar females relative to control males.
1
Yes, chronic exposure of males to MPH
altered some mating behaviours (see figure
2, and replicated G tests results below):
o Reduced posturing (heterogeneity G = 11.26, P = 0.004)
o Increased female initiation (hetero G = 4.05, P = 0.044)
Female exposure to MPH had no significant effects (all P > 0.05) on
any measured behaviours.
2
1
2
3
References
1. Pusey & Wolf 1996 TREE 11:201-206. 2. Mariette et al. 2010 J Evolution Biol 23:1772-1782. 3. Mällo
et al. 2006 Behav Brain Res 177:269-281. 4. Frohmader et al. 2010 Horm Behav 58:149-162. 5. Heyser
et al. 2004 Ann NY Acad Sci 1021:465-469. 6. Solanto 2002 Behav Brain Res 130:65-71. 7. Endler &
Houde 1995 Evolution 49:456-468. 8. Rodd & Sokolowski 1995 Anim Behav 49:1139-1159. 9. Hughes
et al. 1999 Anim Behav 58:907-916. 10. Bell 2010 Ethology 116:448-457.
3Yes, the novelty status of individuals
interacted with the effects of male
exposure to MPH in a mating context
(see figure 3).
Acknowledgements
We thank Anne Houde for helpful advice and comments, and members of the Rodd lab for their
assistance rearing guppies.
Yes, visual familiarity reduced
sexual responsiveness to
potential mates across multiple
measures (see figure 1, table 1 & figure 2).