The Effects of Light Cycle on Metamorphosis in Salamanders

Kenn Rose 1,2 and Christopher K. Beachy 1

1Department of Biology and 2Department of Psychology, Minot State University, Minot ND

Background

Environmental variables affect timing of metamorphosis (e.g. temperature, food availability, predator threat).

Light and Photoperiod have far reaching effects in all facets of nature (flora and fauna).

In the wild, pre-metamorphic Ambystoma tigrinum and A. maculatum are exposed to changing photoperiods.

The damselfly, Lestes viridis

Rolff et al., 2004, American Naturalist

QUESTION ??

• Will changing the length of photoperiod in pre-metamorphic tiger and spotted salamanders mimic environmental cues (seasonal change for example) and affect timing of metamorphosis?

HYPOTHESISHYPOTHESIS

Manipulating exposure to constant and varying photoperiods in larval Ambystoma tigrinum and

A. maculatum will affect timing of metamorphosis.

METHODS & PROCEDURE

Treatments (X4)

L2S

All Short

All Long

S2L

Experiment 1

Lab DesignDOOR

DOOR

Block 3

Block 1

Block 2

Feeding

RESULTS

Morphological traits

Morphology

Pre-metamorphic Post-metamorphic

30

31

32

33

34

35

36

37

light cycle

larval period (days)

Metamorphic Timing

All Short S2L L2S All Long

Experiment 1

Mass at metamorphosis

0

1000

2000

3000

4000

5000

6000

7000

light cycle

metamorphic mass (mg)

All Short S2L L2S All Long

Experiment 1

Confounds to a degree??

Temperature variations were +1° between

Long and Short photoperiods

Temp Effects

From Hickerson et al., 2005, Southeastern Naturalist

Desmognathus quadramaculatus

Blackbelly salamander

100

140

180

220

260

High food, hightemp

Low food, hightemp

High food, lowtemp

Low food, lowtemp

Days to metamorphosis

Experiment 2 Methods

Metamorphic Timing

30

32

34

36

38

40

42

44

46

light-cycle treatment

larval period (days)

All ShortS2LL2SAll Long

Preliminary Results Experiment 2

Preliminary Results Experiment 2

0

200

400

600

800

1000

1200

1400

1600

light-cycle treatment

metamorphic mass (mg)

All ShortS2LL2SAll Long

Mass at metamorphosis

Versus

Discussion: Why the difference?

Ambystoma tigrinum

Tiger Salamander   

Ambystoma maculatum

Spotted Salamander   

© 2003 Twan Leenders

Further Exploration

• Experimentation of species with extended larval periods (to include seasonal expanses).

• Exploration of effects of varying light wavelength on metamorphic timing.• Variation in food amount

Acknowledgements

• Amphibian Growth Project team membersClaude Ouedraogo

Janel Richter

Heidi Richter

Drew Henry

• Karew Schumaker

• Department of Biology