A polymorphism in oocyte pigmentation in natural populations of the glass frog Espadarana prosoblepon (Centrolenidae)
Published: 20 August 2020
María J. Salazar-Nicholls1,2, Francisca Hervas1,3, Sofía I. Muñoz-Tobar1, Ana-Belén Carrillo1, Heisel Ricaurte1, Santiago R. Ron1,4 and Andrés Romero-Carvajal*,1
1Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador (PUCE), Quito, Ecuador, 2Department of Biology, Boston University, Boston, MA, USA, 3Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany and 4Museo de Zoología, PUCE, Quito, Ecuador
The adaptive role of amphibian oocyte melanic pigmentation and its molecular control are still elusive. Here we present evidence of a polymorphism in egg pigmentation in the emerald glass frog Espadarana prosoblepon. In Ecuadorian natural populations of this species, females can lay dark brown or pale eggs that develop into normal pigmented tadpoles and adults. This trait is a sex-limited phenotype which is inherited like a recessive allele that we called pale eggs like (pel). The pel phenotype is exclusive of oocyte cortical melanic pigmentation, which is reduced in comparison to wild type (wt) dark pigmented oocytes. Consequently, pel early embryos are paler in appearance, with reduced melanic pigmentation distributed to early blastomeres and embryonic ectoderm. However, these embryos form normal melanocyte derived pigmentation. Finally, we discuss the origin of this polymorphism and propose the use of E. prosoblepon as a model to study the adaptive role of egg pigmentation.