Mode of maternal provisioning in the fish genus Phalloceros: a variation on the theme of matrotrophy

Abstract The placenta is a complex organ that shows high morphological diversity. Among fish, the first vertebrates that have evolved a placenta, the family Poeciliidae exhibits very diverse modes of maternal provisioning even among congeneric species. Here, we investigated the embryonic growth curv...

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Bibliographic Details
Published in:Biological journal of the Linnean Society 2021-12, Vol.134 (4), p.867-878
Main Authors: Zandonà, Eugenia, Kajin, Maja, Buckup, Paulo A, Amaral, Jeferson Ribeiro, Souto-Santos, Igor C A, Reznick, David N
Format: Article
Language:English
Subjects:
Developmental stages
Embryogenesis
Embryos
Females
Fertilization
Fish
Phalloceros
Placenta
Poeciliidae
Provisioning
Species
Vertebrates
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Summary:Abstract The placenta is a complex organ that shows high morphological diversity. Among fish, the first vertebrates that have evolved a placenta, the family Poeciliidae exhibits very diverse modes of maternal provisioning even among congeneric species. Here, we investigated the embryonic growth curve across seven recently-described species of the highly diverse genus Phalloceros (Eigenmann, 1907). We also investigated possible intraspecific differences and whether other female characteristics affected embryo mass. We found that embryo mass decreased until around stage 20 and then increased, resulting in a 1.5 to 3-fold mass gain from fertilization to birth. Embryo mass changed non-linearly with stage of development and was affected by species identity (or locality) and female somatic dry mass. This initial loss then gain of embryonic mass during development is unique among other Poeciliidae species and was conserved across populations and species, even though size at birth can vary. Other species instead either lose mass if they lack placentas or gain mass exponentially if they have placentas. The Phalloceros mode of maternal provisioning could thus represent a different form from that seen in other species of Poeciliidae.
ISSN:0024-4066
1095-8312
DOI:10.1093/biolinnean/blab121