1. The Effects of Genes
and the Environment
on Wing Polyphenism
by Meghan Fawcett and
Stacey Hou
2. What is Polyphenism?
★ multiple stable developmental endpoints/phenotypes
○ butterflies (patterning--genetic polymorphism)
○ ants (caste)
○ toads
○ soapberry bugs!
3. Soapberry Bugs & why they’re cool
★ Non-sex limited alternate morphs
★ Wing polyphenism
○ differences short and long
○ benefit to the bug?
4. Morphometric Data
Morphometrics shows a mathematical representation of wing
shape. The PC plot shows the range in variation of shape. Based
on our data, lw morphs and sw morphs (indicated by the black and
red dots respectively) differ by a significant amount (p< 0.0001) but
not by sex
5. Environmental Factors
★ Crowding
★ Food quantity
★ We hypothesize that:
○ Low food density (therefore low nutrition) will lead
to more long winged bugs
○ Overcrowding will lead to more long winged morphs
OR =
6. Crowding Experiment
★ Crowding is known to have
effects on living organisms,
including humans
★ Same amount of food as the
control with about 4x the
amount of bugs
★ We expect a higher number of
long winged morphs to short
winged morphs
7. Results of Crowding
★ Crowding has a marginal effect
on wing shape
○ p=0.044
★ In crowded cages we see a
slightly higher incidence of
short winged bugs
★ Tip box bugs more SW even
though crowding is high?
★ Results don’t support our
hypothesis
crowded
not crowded
tip box
8. Food Quantity Experiment
★ Food quantity is directly linked
to nutritional intake, and
therefore quality of life
★ We expect a higher number of
long winged morphs to short
winged morphs
○ this would in theory allow the
bugs to fly to areas with
better resources
9. Results of Food Quantity
★ Food quantity has a significant
effect on wing shape
○ p = 0.016 in a two-way ANOVA
with morph and food
★ High Food = more SW
○ Enough resources are
available for future offspring
★ Low Food = more LW
○ Can leave to find better
resources
★ Our results support our hypothesis!
LW
low food
SW
high food
10. More Food Quantity Results
★ There is a significant
correlation between food
quantity and SW morph
○ fisher’s exact test:
p<0.0001
★ Additionally, survival rate
goes up by a significant
amount when food is
increased
11. Single Mating Pairs
★ To investigate fecundity of wing morphs
○ Are short winged bugs more fertile than long winged?
○ data so far suggests:
■ short winged females may the most fertile morph
● beneficial to females and detrimental to males of
the same species???!!!
LW X LW LW♀ x SW♂ SW♀ X LW♂ SW X SW
6.92 5.03 5.21 2.78
12. Results of the Fecundity Study
★ Results indicate that long-winged males
are significantly more successful than
short-winged males
★ Double long winged crosses show the
greatest range and the highest average
○ however there is also about twice
as much data for those crosses
★ Short-winged females tend to be more
successful with long-winged males than
short-winged males
13. RNAi
★ Investigating the effect of InR and
FoxO--important factors of the
insulin signaling pathway--on
wing morph
★ If these genes are inhibited,
growth factor should be down
regulated and therefore there
should be more SW morphs
14. Morph ratios in RNAi bugs
InR GFP FoxO
percentSWxLW
★ The results indicate that
there are significantly more
short-winged morphs in
comparison to the control
for FoxO injected bugs.
★ Additionally, the InR
injected bugs also should a
statistical trend towards
greater numbers of short-
winged bugs than the
control.
15. Going Forward...
★ More crosses are required for
the fecundity studies in single
pair matings
★ More RNAi most specifically
for InR
★ Insulin injections
MEGHAN:
the focus of our project is on polyphenism, which is a very cool process which is common to a number of different species, most interestingly including soap berry bugs. Polyphenism shouldn’t be confused with polymorphism, which is evident in butterfly wing patterning, where although all individuals are of the same species they have different genotypes which are heritable and genetically influenced. Polypenism on the other hand results in multiple phenotypes from the same genotype. for example, ants develop different morphs based on caste systems, or their role in the colony. Spade foot toads develop different sizes in response to stress and in order to cannibalize their smaller counterparts.
MEGHAN:
polyphenism manifests itself in soapberry bugs in wingmorph. There are two different end points for wing morph, short winged and long winged.
both of the bugs shown below are male PK13 individuals, but of different wing morphs. The short winged and long winged morphs are differentiated by the MEMBRANE section of the wing, or as we call it “the no mans land” there is no defined patterning to the wings in this area
This second set of images shows how we measure the wings, we choose 42 landmarks to define the total shape of the bug
STACEY
STACEY:
why we believe this to be true: if there is high food, then there is less of a necessity to leave and find food elsewhere, so bugs don’t need to fly away to find new resources, and can therefore focus on fertility. If there is overcrowding, there is probably also a shortage of resources, leading to the necessity for more long winged bugs so they can travel to areas of higher food density, and a lesser importance is placed on fertility
Find the original articles: conditions → good → more babies
Origonally based on a hypothesis about aphids
MEGHAN: one of the environmental factors we are testing is the effect of crowding, in general crowding can have a lot of negative effects on an individual, and can induce huge amounts of stress. We hypothesized that this stress will lead to higher number of long-winged bugs, so instead of focusing on fertility and producing more bugs and increasing the crowding problem, the bugs will be able to leave their stressful situations
MEGHAN: it seems as though increased amounts of crowding actually induces higher numbers of short winged bugs. This could be due to the stressful environment i mentioned earlier. and instead of allowing more LW to develop, the stress is negatively impacting the expression of growth hormone, or in turn suppressing something within the insulin signaling pathway which is causing a suppression in wing growth
STACEY
STACEY
(black = LW high; red=LW low; green=SW high; blue=SW low) The high food bugs are generally higher on the PC2 axis. Also, notice how few SW bugs came from the low food treatments.
STACEY
MEGHAN: fecundity is the main reason we think that there is the persistance of the wing morph. Therefore, in order to investigate the role of fecundity we set up a number of individual mating pairs
