Embryonic staging series for the African House Snake (Lamprophis fuliginosus) using external morphology Eric Dichter and Scott Boback. Department of Biology, Dickinson College, Carlisle, PA.

Outline The motivation The question African House staging series Continuing work Goals for future

Darwin’s finches – morphological variation of beaks

Bone morphogenetic protein (Bmp4) Abzhanov et al. 2004

Bmp4

Is Bmp4 responsible for head shape differences between island and mainland boas?

African House Snake staging series oviparous smaller size shorter time of development docile VERY prolific reproduction

Staging criteria for Rock Python StageExternal morphological characteristics 1Mandibular process does not extend to eye, no scales, 5-6 body coils 2Mandibular process extending rostral to eye 3Mandibular process extends midway between eye and maxilla, scales visible on body, 3-4 body coils 4Mandibular process lines up with maxilla, 3 coils 5Cervical flexure > 90°, heart protrudes from body cavity 6Scales on head, heart internalized, 2-3 coils 7Fusion of eyelids in center of eye, 2 coils 8Cervical flexure 120°, body wall closed, pigmentation beginning, 2 coils 9Cervical flexure 180°, brain not visible through skin, pigmentation patter clear but pale, 1-2 coils 10Resembles neonate, 1-2 body coils, egg tooth visible Adapted from Boughner et al. 2007

Staging criteria for African House Mandibular length (relative to maxilla) Brain development Location of organs Angle of cervical flexure Weight Length Eye pigment Scales Adapted from Boughner et al. 2007

0-1 days Mandible Visible, protruding mesencephalon External organs

6 days Mandible External organs Visible, protruding mesencephalon

9 days Mandible External organs Visible, protruding mesencephalon

13 days Mandible External heart Visible, protruding mesencephalon

16 days Mandible Visible, protruding mesencephalon Internalized heart (moved caudally)

13’ days Mandible Scales forming Visible, protruding mesencephalon

16’ days Mandible Visible, flattening mesencephalon

27 days Pigmentation pattern beginning Visible, linearized skull

34 days Pigmentation pattern darkening Opaque, elongate skull

43 days Pigmentation pattern darkening further External hemipenes

54 days - hatched

Conclusions Rate of development variable – depends on environment, health of mother, genetics Comparable development at oviposition Development of L. fuliginosus similar to Python sebae – much shorter incubation

Continuing work Mating snakes, incubating eggs, harvesting more embryos Clearing and staining – location, timing of bone development in jaws In situ hybridizations – determine presence, location, timing of expression of certain growth factors (Bmp4, Bmp2, Fgf8, Shh)

Many thanks to… Prof. Boback Prof. Mistry Neil Ford Ali Maksimak Mike Montross Chase Walling

Works cited Boughner, J.C., Buchtova, M., Fu, K., Diewert, V., Hallgrimsson, B., Richman, J.M Embryonic development of Python sebae – I: Staging criteria and macroscopic skeletal morphogenesis of the head and limbs. Zoology Abzhanov, A., Protas, P., Grant, B. R., Grant, P.R., Tabin, C.J Bmp4 and Morphological Variation of Beaks in Darwin’s Finches