Life History of Phalloceros caudiomaculatus: A Novel Variation on the Theme of Livebearing in the Family Poeciliidae
We describe the life-history pattern of Phalloceros caudiomaculatus on the basis of wild-caught and preserved fish from four different South American locations and laboratory data on livestock from a fifth location. This species is matrotrophic; the estimated dry weight of the young at birth is up to five times the weight of eggs at fertilization. In addition, these fish lack superfetation, meaning that there is only one brood of developing young at a time. This observation suggests that matrotrophy and superfetation can evolve independently of one another. The size distribution of mature males was bimodal in two of three samples and significantly skewed in the third. Such size distributions have indicated the presence of a genetic polymorphism for age and size at maturity in other species of Poeciliidae.Abstract
Mean embryo weight as a function of the stage of development. Abbreviations follow Reznick and Endler (1982): uneyed (UE), early eyed (EE), middle eyed (ME), late eyed (LE), and very late eyed (VLE). (A) Paraguay, (B) Rio Silva, (C) Rio Puruba, (D) Arroyo Afluente. Note that the scales on the y-axis vary among localities to accommodate differences in the range of mean embryo weight
Size-frequency distributions of mature and immature males of Phalloceros caudomaculatus in three of the four field collections. Open bars = mature males; closed bars = immature males. (A) Paraguay, (B) Rio Silva, (C) Rio Puruba