Mode of maternal provisioning in the fish genus <i>Phalloceros</i>: a variation on the theme of matrotrophy

Zandonà, Eugênia; Kajin, Maja; Buckup, Paulo Andreas; Amaral, Jeferson Ribeiro; Souto-Santos, Igor Cavalcanti de Araújo; Reznick, David N.

doi:10.1093/biolinnean/blab121

Cited by 5 publications

(1 citation statement)

References 32 publications

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“…For instance, some poeciliid species exhibit moderate and extensive placentotrophy without superfetation (e.g. most Phalloceros and Pamphorichthys species; [37]). In these taxa, the evolution of advanced placentotrophy is hardly explained by the preceding evolution of advanced degrees of superfetation, because they all lack superfetation.…”

Section: Discussionmentioning

confidence: 99%

Increased superfetation precedes the evolution of advanced degrees of placentotrophy in viviparous fishes of the family Poeciliidae

et al. 2022

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The causes and consequences of the evolution of placentotrophy (post-fertilization nutrition of developing embryos of viviparous organisms by means of a maternal placenta) in non-mammalian vertebrates are still not fully understood. In particular, in the fish family Poeciliidae there is an evolutionary link between placentotrophy and superfetation (ability of females to simultaneously bear embryos at distinct developmental stages), with no conclusive evidence for which of these two traits facilitates the evolution of more advanced degrees of the other. Using a robust phylogenetic comparative method based on Ornstein–Uhlenbeck models of adaptive evolution and data from 36 poeciliid species, we detected a clear causality pattern. The evolution of extensive placentotrophy has been facilitated by the preceding evolution of more simultaneous broods. Therefore, placentas became increasingly complex as an adaptive response to evolutionary increases in the degree of superfetation. This finding represents a substantial contribution to our knowledge of the factors that have shaped placental evolution in poeciliid fishes.

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Section: Discussionmentioning

confidence: 99%

Increased superfetation precedes the evolution of advanced degrees of placentotrophy in viviparous fishes of the family Poeciliidae

et al. 2022

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Reproductive Strategy of the Annual Fish Leptopanchax Opalescens (Rivulidae) and Trade-Off Between Egg Size and Maximum Body Length in Temporary Wetlands

et al. 2023

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Leptopanchax opalescens is a critically endangered small annual sh. Reproductive traits of this species were studied to improve our understanding of the strategies that facilitate the occupation of temporary wetlands. We compiled egg diameter and maximum total length (TLmax) data from 132 neotropical freshwater sh (83 genera, 43 families) to establish comparisons with this species. We used the egg diameter / TLmax ratio to test the hypothesis that annual sh in temporary wetlands have relatively larger eggs than non-annual species from perennial habitats (lakes, rivers). Fish were collected from Guandu River drainages (Brazil). DNA barcoding was employed to con rm the species identity. The phases of gonadal development and spawn type were described using histological techniques. Egg size and fecundity were determined with microscopic analysis. Females with batch spawning and males with continuous spawning were detected. The bath fecundity ranged from 22-32 vitellogenic oocytes (mean 27 ± 7 SD). Annual species presented greater relative egg size than perennial species (p < 0.001), which is an indication of greater reproductive investment at the expense of somatic growth in temporary wetlands. Larger eggs are advantageous for annual sh as their lifespan is limited, and they can allocate a greater amount of yolk reserves for long periods buried in the substrate under embryonic diapause. Large relative oocytes, spawning in batches, synchronous modal development of oocytes, continued production of sperm in males, and a complex process of embryonic diapause are reproductive traits that favor resilience of L. opalescens and other annual sh in temporary wetlands. IntroductionRivulidae (Cyprinodontiformes) is the eighth most speciose sh family in the World, with 471 valid species (Fricke et al. 2022), and the rst in number of threatened species in the Neotropical Region, where they occur. The threat is such that in a megadiverse country like Brazil, a single family of freshwater sh (i.e., Rivulidae) has a higher number of threatened species (130 spp.) than all classes of marine sh combined (Actinopterygii + Chondrichthyes + Myxini = 97 spp.) (ICMBio 2018). Habitat loss is the main threat to rivulids. The swamps and temporary wetlands where many of these animals inhabit have been drastically destroyed, due to deforestation, drainage and land lling resulting from agricultural and urban expansion (Loureiro et al. 2018;Castro and Polaz 2020). Loss of temporary wetlands from land alterations has signi cant ecological and social consequences (Calhoun et al. 2017), but freshwater research, policy, and conservation have historically neglected these habitats, focusing instead on larger water bodies and agship species (

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Do mismatched genitalia promote mechanical isolation in syntopic species of Phalloceros fishes (Poeciliidae)?

Jennings

Souto-Santos

Buckup

et al. 2023

Zoological Journal of the Linnean Society

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The elucidation of mechanisms responsible for the reproductive isolation of species is a fundamental part of speciation research. South American poeciliid fishes in the genus Phalloceros represent a promising system in which to study the evolution of reproductive barriers between closely related species. Phalloceros are often found in sympatry with non-sister congeners, and most such species pairs have morphologically divergent female and male genitalia. In recent studies, it has been hypothesized that mismatched genitalia between co-occurring Phalloceros species might act as mechanical barriers to prevent hybridization and might help to explain the diversification of this group. However, this idea has not yet been evaluated empirically with genetic data. Here, we tested this hypothesis using morphological data in conjunction with mitochondrial and nuclear DNA sequence data. Our study focused on Phalloceros anisophallos and Phalloceros leptokeras, two non-sister species that have mismatched genitalia and that occur together in at least four rivers in south-eastern Brazil. Despite the prevalence of hybridization between closely related non-sister species of animals, especially fish, our phylogenetically-based results detected no evidence of mitonuclear discordance and (hence historical hybridization) between the two focal species. Our findings are therefore consistent with the hypothesis that mismatched genitalia prevent hybridization between sympatric species of Phalloceros fishes.

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

Cited by 5 publications

References 32 publications

Increased superfetation precedes the evolution of advanced degrees of placentotrophy in viviparous fishes of the family Poeciliidae

Increased superfetation precedes the evolution of advanced degrees of placentotrophy in viviparous fishes of the family Poeciliidae

Reproductive Strategy of the Annual Fish Leptopanchax Opalescens (Rivulidae) and Trade-Off Between Egg Size and Maximum Body Length in Temporary Wetlands

Do mismatched genitalia promote mechanical isolation in syntopic species of Phalloceros fishes (Poeciliidae)?

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