Mycalesis mineus

Musa sp.

-30.0 -20.0 -10.0 0 0

Microstegium ciliatum

2.5 5.0 7.5 10.0δ13C (‰) δ15N (‰)

5-10 11-15 16-20 21-25 26-30Days since eclosion

Prop

ortio

n of

larv

al d

iet (

%)

70

60

50

40

30

20

10

05-10 11-15 16-20 21-25 26-30

Days since eclosion

Prop

ortio

n of

larv

al d

iet (

%)

70

60

50

40

30

20

10

0

Starvation and thermal consequences for resource allocation and reproduction in a polyphenic butterfly

Introduction

Results & Discussion

Conclusion

Reference

Adult diet is vital to egg reproduction, as

Nicole YU Supervisor: Dr. Timothy C. BONEBRAKE

Half of the caterpillars were transferred to 17°C upon reaching their final instar

Phenotypic plasticity is where organisms respond to environmental cues, and develop different traits and characteristics1. Eggs were collected from wild-caught

gravid females, and reared separately at 27°C

Half of the emerged females were provided with bananas upon eclosion, and the other half starved for 4 days

Source isotopic values

Bayesian Mixing Model

Eggs were collected and counted daily and stored at -20°C.

Bulk SIA data was analyzed using A Bayesian mixing model

Butterfly rearing

Stable Isotopes analysis

1. Whitman, D., & Agrawal, A. (2009). What is Phenotypic Plasticity and Why is it Important? In Phenotypic Plasticity of Insects. Science Publishers.van Bergen, E., Osbaldeston, D., Kodandaramaiah, U., Brattström, O., 2. Aduse-Poku, K., & Brakefield, P. M. (2017). Conserved patterns of integrated developmental plasticity in a group of polyphenic tropical butterflies. BMC Evolutionary Biology, 17(1). doi:10.1186/s12862-017-0907-13. Hood-Nowotny, R., & Knols, B. G. J. (2007). Stable isotope methods in biological and ecological studies of arthropods. Entomologia Experimentalis et Applicata, 124(1), 3–16.

Fig 2. Dietary proportion (%) of larval diet contributing to egg production, for wet season (left) and dry season forms (right) across days since eclosion

Phenotypic forms of Mycalesis mineus are determined by thermal conditions during final instar and early pupation period 2.

Isotopic values of organisms reflect their diet, and C3 and C4 plants differ greatly in their 12C and 13C 3. M. mineus larval and adult diets are C4 and C3 plants respectively.

What are the effects of starvation to resource allocation in reproduction of different phenotypes of M. mineus?

little fractionation from the larval diet to the butterfly stage

Main question

We can derive the proportional contributions of adult and larval diet to eggs from the eggs’ bulk isotopic signatures, and compare how the two phenotypes allocate their resources.

Answers using stable isotope analysis

There is a decreasing trend in the proportion of larval diet contribution to eggs with time, except for starved dry season forms.

No significant difference is found between treatments

However, credible intervals are large, e.g. For larval diet proportion of starved wet season form, the max. is 62.8% and min. is 10.0%.

UID 3035445962

Research Colloquium for Science UG Students 2020-21

No eggs were laid during the in the first 5 days since eclosion

MethodologyCaterpillar rearing

Ecology & Biodiversity

Fig 1. Means and sd of δ13C and δ15N (‰) of Microstegium ciliatum (n = 3), Musa sp. (n = 3), and freshly eclosed female Mycalesis mineus (n = 4)

Females were introduced to 1-3 males day within 3 days since eclosion.

1. Mycalesis mineus females will not oviposit until it has fed

2. Adult diet contribution towards egg production is likely over 60% in the early egg-laying period, and over 70% after 10 days

4-5 oven-dried eggs from each individual each day formed a sample, weighing between 0.297 - 0.407mg.

27°C

17°C

Sartoriusmicrobalance

C3 plantC4 plantMicrostegium ciliatum Musa

Dry season form

reduced eyespots

Wet season form

conspicuous eyespotssmaller in size larger in size

Mean δ13C of freshly eclosed M. mineus females resembles that of M. ciliatum

Mean δ15N of freshly eclosed M. mineus females is 2.9‰ higher than that of the M. ciliatum.

The two food sources are vastly different in both mean δ13C and mean δ15N. dietary proportions to egg contribution can be easily distinguised using both δ13C and δ15N values

freshly eclosed M. mineus females are enriched in δ15N

faster larval growth slower larval growth

Trophic discrimination factorsTrophic discrimination factors were derived from the food sources, using the isotopic values from freshly eclosed female butterflies

Trophic discrimination throughout the adult life of M. mineus was assumed to be the same as the larval fractionation

Mean ± SDStable isotope (‰)

δ13C δ15N

0.77 ± 0.672.36 ± 1.03

Table 1. Mean ± SD for calculated trophic discrimination factors for δ13C and δ15N

5 x 3.5 mm2

tin capsules

sp.