Jessica Vroonen
Introduction Lizards: very diverse colour patterns intra- and interspecific differences in colour
Introduction Lizards intra- and interspecific differences in colour
Introduction Lizards intra- and interspecific differences in colour Male 1 Male 2 Female Eumeces laticeps
Introduction Functions of colour: Thermoregulation
Introduction Functions of colour: Thermoregulation Intraspecific communication
Introduction Functions of colour: Thermoregulation Intraspecific communication Crypsis...
Introduction Functions of colour: Thermoregulation Intraspecific communication Crypsis...
Introduction Parameters of predation:
Introduction Parameters of predation: Attack rate of plasticine models Presence of predators Tail shedding Antipredator behaviour Background matching (reflectance)...
Body colouration fixed or flexible physiological morphological colour change ontogenetic
Body colouration fixed
Body colouration fixed : Lacerta perspicillata --> behaviour Podarcis melisellensis --> background matching + predation intensity
Fixed body colouration Lacerta perspicillata: 2 morphs: linear & spotted Carretero et al. (2006) Can. J. Zool., 84: 1594-1603.
Fixed body colouration Lacerta perspicillata: 2 morphs: linear & spotted Antipredator behaviour Carretero et al. (2006) Can. J. Zool., 84: 1594-1603.
Fixed body colouration Lacerta perspicillata: 2 morphs: linear & spotted Antipredator behaviour Approach distance Carretero et al. (2006) Can. J. Zool., 84: 1594-1603.
Fixed body colouration Lacerta perspicillata: 2 morphs: linear & spotted Antipredator behaviour Approach distance Distance fled Carretero et al. (2006) Can. J. Zool., 84: 1594-1603.
Fixed body colouration Lacerta perspicillata: results Carretero et al. (2006) Can. J. Zool., 84: 1594-1603.
Fixed body colouration Lacerta perspicillata: conclusion longer approach distance more time to reappear Carretero et al. (2006) Can. J. Zool., 84: 1594-1603.
Fixed body colouration Podarcis melisellensis: melanism Copyright Bart Vervust Copyright Bart Vervust Copyright Bart Vervust
IntrodIntroduction Vis
IntrodIntroduction Copyright Bart Vervust Vis
IntrodIntroduction Vis Copyright Bart Vervust Mali Parzan
IntrodIntroduction Copyright Bart Vervust Mali Barjak Vis Copyright Bart Vervust Mali Parzan
IntrodIntroduction Copyright Bart Vervust Mali Barjak Vis Copyright Bart Vervust Mali Parzan Brusnik Copyright Bart Vervust
Fixed body colouration Podarcis melisellensis: melanism Thermoregulatory benefit? Higher predation risk? Adaptation to darker background? Lower predation risk?
Fixed body colouration Podarcis melisellensis: melanism Background matching Predation intensity
Fixed body colouration Podarcis melisellensis: melanism Reflectance Avantes spectrometer Avaspec-2048-USB2-UA-50 Lizard: 8 dorsal spots Background (stones) 300-700nm Irradiance Avaspec-2048-USB2-UA-50 Sunny days (10-16h)
Fixed body colouration Podarcis melisellensis: melanism Background matching Achromatic contrast = (Ra l Ra b )/(Ra l + Ra b ) Chromatic contrast = (Q l (λ) - Q b (λ))² Mixed model
Fixed body colouration Podarcis melisellensis: melanism Predation intensity Plasticine models 100 models / island 42-67h Attack scored 1: at least one beak mark 0: not attacked Generalized linear model
Fixed body colouration Podarcis melisellensis: reflectance lizards
Fixed body colouration Podarcis melisellensis: reflectance background
Fixed body colouration Podarcis melisellensis: achromatic contrast
Fixed body colouration Podarcis melisellensis: achromatic contrast
Fixed body colouration Podarcis melisellensis: chromatic contrast
Fixed body colouration Podarcis melisellensis: chromatic contrast
Fixed body colouration Podarcis melisellensis: predation intensity *** *: p<0.05; **: p<0.01; ***: p<0.001
Fixed body colouration Podarcis melisellensis: conclusion Brusnik: Volcanic island Lower reflectance Most achromatic camouflage Melanistic lizards: achromatically most conspicuous chromatically less contrasting
Fixed body colouration Podarcis melisellensis: conclusion Mali Barjak and Mali Parzan Cryptic lizards Background: less camouflage (achromatic) Vis most conspicuous normal coloured lizard low predation intensity
Body colouration fixed or flexible physiological morphological colour change ontogenetic
Body colouration physiological colour change --> adjust colour to environment
Body colouration physiological colour change --> adjust colour to environment Moorish gecko (Tarentola mauritanica): background Dwarf chameleon (Bradypodion taeniabronchum): predator
Physiological colour change Moorish gecko Different backgrounds (white, grey & black) Different temperatures (15-35 C) Different light conditions (dark or illuminated) Reflectance 6 dorsal spots: 300-700nm Avaspec spectrometer (Avantes)
Physiological colour change Moorish gecko: results
Physiological colour change Moorish gecko: conclusion Adjusts colour to background Light seems to be a necessary trigger Temperature no straightforward effect
Physiological colour change Dwarf chameleon Stuart-Fox et al. (2008) Biol. Lett., 4: 326-329.
Physiological colour change Dwarf chameleon 2 predator types: stuffed fiscal shrike & boomslang Reflectance measurements when chameleon showed antipredator behaviour background Visual modelling Stuart-Fox et al. (2008) Biol. Lett., 4: 326-329.
Physiological colour change Dwarf chameleon: results Stuart-Fox et al. (2008) Biol. Lett., 4: 326-329.
Physiological colour change Dwarf chameleon: results Stuart-Fox et al. (2008) Biol. Lett., 4: 326-329.
Physiological colour change Dwarf chameleon: conclusion Better background matching in response to birds More camouflaged for snakes visual system --> poorer colour discrimination of snakes Stuart-Fox et al. (2008) Biol. Lett., 4: 326-329.
Body colouration fixed or flexible physiological morphological colour change ontogenetic
Ontogenetic colour change Juvenile <---> Adult
Ontogenetic colour change Juvenile <---> Adult Acanthodactylus: Dorsal pattern Tail colour Increased movement hypothesis: juveniles more vulnerable to predation due to increased activity Hawlena (2009) Behav. Ecol. Sociobiol., 64: 205-213.
Ontogenetic colour change Acanthodactylus Adjusted from Hawlena (2009) Behav. Ecol. Sociobiol., 64: 205-213.
Ontogenetic colour change Acanthodactylus Foraging behaviour Tail displays Hawlena (2009) Behav. Ecol. Sociobiol., 64: 205-213.
Ontogenetic colour change Acanthodactylus: results Hawlena (2009) Behav. Ecol. Sociobiol., 64: 205-213.
Ontogenetic colour change Acanthodactylus: results Hawlena (2009) Behav. Ecol. Sociobiol., 64: 205-213.
Ontogenetic colour change Acanthodactylus: results Hawlena (2009) Behav. Ecol. Sociobiol., 64: 205-213.
Ontogenetic colour change Acanthodactylus: conclusion Tail colour: Fades --> less risky behaviour Dorsal colour: Striped --> spotted: more active when striped Spotted --> spotted: no change in behaviour Striped --> striped: A. schreiberi: no change in behaviour A. boskianus: hatchlings less mobile than adults
Conclusion High diversity in colour patterns Different mechanisms: fixed <---> colour change Colour related with several aspects of predation: Behaviour Background matching Predation intensity
Acknowledgements Promotor: Raoul Van Damme Bart Vervust, Irena Grbac, Bojan Lazar, Valeria Maselli & Domenico Fulgione Functional Morphology Lab