MADAGASCAR DISSERTATION/THESIS PROJECT

MA53 - Sound-induced colour-change modulation in day geckos

Prepared by Dr Peter Long, University of Oxford

For more information contact: Dr Heather Gilbert | Terrestrial research officer | [email protected]

Koch’s giant day gecko, kochi, is one of the most abundant found in the Mahamavo forest. At mid-day adults are a bright green colour. Previous research has indicated that these lizards will change colour from green to brown when hearing a variety of sounds, including alarm-calls from the Paradise Flycatcher, calls from the Madagascar Buzzard (a potential predator) as well as simply white noise. The biological mechanism for this colour change is well characterized, but the triggering stimulus is not. Colour-change is quite rapid occurring in about fifteen seconds or so and returns to its original green in just a few minutes. Colour can be quantified using standardized photographs and statistical comparisons can be conducted comparing hue, saturation and lightness values from photographs taken before and after stimulation. Colour change here is sensitive enough that the specific characteristics of sound that cause colour modulation will be addressed. Other bird (and lemur calls) will be tested as well sounds of different intensity and frequency to determine the threshold levels required to elicit colour-change in these lizards. It will also be determined if these lizards can change colour in a quantitative fashion or if this is more of an all-or-nothing response.

Suggested reading

*Brown, Jason L, et al. (2016), ‘Spatial Biodiversity Patterns of Madagascar’s Amphibians and ’, PLoS One, 11 (1), https://doi.org/10.1371/journal.pone.0144076

*Jenkins, Richard K B, et al. (2014), ‘Extinction Risks and the Conservation of Madagascar’s Reptiles’, PLoS One, 9 (8), https://doi.org/10.1371/journal.pone.0100173

Austin, JJ, EN Arnold, and CG Jones (2004), ‘Reconstructing an island radiation using ancient and recent DNA: the extinct and living day geckos (Phelsuma) of the Mascarene islands’, Mol. Phylogenet. Evol., 31 (1), 109-22.

Blumgart, Dan, Julia Dolhem, and Christopher J Raxworthy (2017), ‘Herpetological diversity across intact and modified habitats of Nosy Komba Island, Madagascar’, J. Nat. Hist., 51 (11- 12), 625-42.

Buckland, Steeves, et al. (2014), ‘Ecological Effects of the Invasive Giant Madagascar Day Gecko on Endemic Mauritian Geckos: Applications of Binomial-Mixture and Distribution Models’, PLoS One, 9 (4),

Glaw, Frank and Herbert Roesler (2015), ‘Taxonomic checklist of the day geckos of the genera Phelsuma GRAY,1825 and Rhoptropella HEWITT, 1937 (: )’, Vertebr. Zool., 65 (2), 247-83.

Ikeuchi, I, A Mori, and M Hasegawa (2005), ‘Natural history of Phelsuma madagascariensis kochi from a dry forest in Madagascar’, Amphib. Reptil., 26 (4), 475-83.

Penny, Samuel G, et al. (2017), ‘Combining old and new evidence to increase the known biodiversity value of the Sahamalaza Peninsula, Northwest Madagascar’, Contrib. Zool., 86 (4), 273-95.

Rocha, Sara, et al. (2010), ‘Phylogenetic systematics of day geckos, Phelsuma, based on molecular and morphological data (Squamata: Gekkonidae)’, Zootaxa, 1-28.

Stanley, Richard C and Christopher J Raxworthy (2016), ‘Rediscovery of the enigmatic day gecko Phelsuma masohoala in northeast Madagascar’, Herpetol. Conserv. Biol., 11 (3), 402-7.