Vestigial structures or organs are classified as those that have evolved over time to become rudiments of their ancestral forms and in many occurrences are non-functional for their original, ancestral use.

Ryshonda Patrice Lewis, Fayetteville State University Presence of Bidder's organs is a derived condition in the context of anurans as a whole, but primitive within the family Bufonidae.Vestigial skeletal structures in four snake species and five species of dibamid and scincid lizards

The organs are gynomorphs in males and highly variable as vestigial structures, but may well have endocrinogenic functions in both sexes although gametogenic functions in nature have been lost in males. In those groups, Bidder's organs normally persist, always in males and often in females, as an undifferentiated ovaroid or ovary in a non-functional transition between the ancestral state and modification as part of the fat body. Some members of the genus Bufo retain considerable hyperfecundity, but in derived species of Bufo and genera of Bufonidae a spectrum of ovarian reduction exists. Our findings suggest that localized modifications in the circulatory system may have contributed to the evolution of vestigial eyes in cavefish.ĪbstractBidder's organs in both male and female bufonids are hypothesized to represent a transitory state in an evolutionary transformation from extensive, hyperfecund ovaries to smaller, less fecund ones-a transformation that other families of anurans experienced in forms now long extinct. The inactivation of cbsa affects eye development by increasing the transsulfuration intermediate homocysteine and inducing defects in optic vasculature, which result in aneurysms and eye hemorrhages. Here we identify cystathionine ß-synthase a (cbsa), which encodes the key enzyme of the transsulfuration pathway, as one of the mutated genes responsible for eye degeneration in multiple cavefish populations.

The mutated genes involved in cavefish vestigial eye formation have not been characterized. Cavefish embryos initially develop eyes, but they subsequently degenerate and become vestigial structures embedded in the head. This study examines vestigial eye formation in the teleost Astyanax mexicanus, which consists of a sighted surface-dwelling morph and multiple populations of blind cave morphs. Vestigial structures are key indicators of evolutionary descent, but the mechanisms underlying their development are poorly understood.

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