Viviparity: The Maternal-Fetal Relationship in Fishes

Wourms, John P.

doi:10.1093/icb/21.2.473

Cited by 504 publications

(473 citation statements)

References 54 publications

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“…The acceleration of embryonic development occurs during the non-feeding lecithotrophic stages of development (S. s. bernardezi; Buckley et al, 2007), and is also facilitated by cannibalistic feeding in the post-hatching stage via oophagy, ingestion of eggs, and adelphophagy, and ingestion of larvae; (Dopazo and Alberch, 1994;Wourms, 1981;Greven, 1998). Thus, viviparity in our island populations could be determined not only through physiological and/or genetic mechanisms but also through oviductal retention of the larvae, allowing the embryos and hatchlings to grow faster and metamorphose before birth.…”

Section: Genetic Isolation Vs Environmental Factors For Viviparity Inmentioning

confidence: 99%

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

2011

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Continental islands offer an excellent opportunity to investigate adaptive processes and to time microevolutionary changes that precede macroevolutionary events. We performed a population genetic study of the fire salamander (Salamandra salamandra), a species that displays unique intraspecific diversity of reproductive strategies, to address the microevolutionary processes leading to phenotypic and genetic differentiation of island, coastal and interior populations. We used eight microsatellite markers to estimate genetic diversity, population structure and demographic parameters in viviparous insular populations and ovoviviparous coastal and interior populations. Our results show considerable genetic differentiation (F ST range: 0.06-0.27), and no clear signs of gene flow among populations, except between the large and admixed interior populations. We find no support for island colonization by rafting or intentional/accidental anthropogenic introductions, indicating that rising sea levels were responsible for isolation of the island populations approximately 9000 years ago. Our study provides evidence of rapid genetic differentiation between island and coastal populations, and rapid evolution of viviparity driven by climatic selective pressures on island populations, geographic isolation with genetic drift, or a combination of these factors. Studies of these viviparous island populations in early stages of divergence help us better understand the microevolutionary processes involved in rapid phenotypic shifts.

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Section: Genetic Isolation Vs Environmental Factors For Viviparity Inmentioning

confidence: 99%

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

2011

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“…Though there have been numerous origins of parental care, there have been very few transitions to higher levels of maternal investment, such as placentation, in vertebrates (Wourms 1977;Wourms 1981;Dulvy and Reynolds 1997). Live-bearing is thought to have evolved more than 125 times in vertebrates (Shine 1989;Clutton-Brock and Godfrey 1991), with most transitions occurring in squamate reptiles and ,9 or 10 transitions occurring in chondrichthyans (Dulvy and Reynolds 1997;Reynolds et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Does more maternal investment mean a larger brain? Evolutionary relationships between reproductive mode and brain size in chondrichthyans

Mull

Yopak

Dulvy

2011

Mar. Freshwater Res.

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Abstract. Chondrichthyans have the most diverse array of reproductive strategies of any vertebrate group, ranging from egg-laying to live-bearing with placental matrotrophy. Matrotrophy is defined as additional maternal provisioning beyond the yolk to the developing neonate; in chondrichthyans, this occurs through a range of mechanisms including uterine milk, oophagy, uterine cannibalism and placentotrophy. Chondrichthyans also exhibit a wide range of relative brain sizes and highly diverse patterns of brain organisation. Brains are energetically expensive to produce and maintain, and represent a major energetic constraint during early life in vertebrates. In mammals, more direct maternal-fetal placental connections have been associated with larger brains (steeper brain-body allometric scaling relationships). We test for a relationship between reproductive mode and relative brain size across 85 species from six major orders of chondrichthyans by using several phylogenetic comparative analyses. Ordinary least-squares (OLS) and reduced major axis (RMA) regression of body mass versus brain mass suggest that increased maternal investment results in a larger relative brain size. Our findings were supported by phylogenetic generalised least-squares models (pGLS), which also highlighted that these results vary with evolutionary tempo, as described by different branch-length assumptions. Across all analyses, maximum body size had a significant influence on the relative brain size, with large-bodied species (body mass .100 kg) having relatively smaller brains. The present study suggests that there may be a link between reproductive investment and relative brain size in chondrichthyans; however, a more definitive test requires a better-resolved phylogeny and a more nuanced categorisation of the level of maternal investment in chondrichthyans.

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“…Viviparous species may transfer nutrients to their embryos in various ways, either through the other embryos (oophagy and adelphophagy), from the parent through placental analogues or through the yolk sac placenta (Wourms 1981). Oophagy and adelphophagy represent forms of sibling competition that may reduce parental fitness (Trivers 1974).…”

Section: Introductionmentioning

confidence: 99%

Brooding fathers, not siblings, take up nutrients from embryos

et al. 2009

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It is well known that many animals with placenta-like structures provide their embryos with nutrients and oxygen. However, we demonstrate here that nutrients can pass the other way, from embryos to the parent. The study was done on a pipefish, Syngnathus typhle, in which males brood fertilized eggs in a brood pouch for several weeks. Earlier research has found a reduction of embryo numbers during the brooding period, but the fate of the nutrients from these 'reduced' embryos has been unknown. In this study, we considered whether (i) the brooding male absorbs the nutrients, (ii) siblings absorb them, or (iii) a combination of both. Males were mated to two sets of females, one of which had radioactively labelled eggs (using 14 C-labelled amino acids), such that approximately half the eggs in the brood pouch were labelled. This allowed us to trace nutrient uptake from these embryos. We detected that 14 C-labelled amino acids were transferred to the male brood pouch, liver and muscle tissue. However, we did not detect any significant 14 C-labelled amino-acid absorption by the non-labelled half-siblings in the brood pouch. Thus, we show, to our knowledge, for the first time, that males absorb nutrients derived from embryos through their paternal brood pouch.

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Viviparity: The Maternal-Fetal Relationship in Fishes

Cited by 504 publications

References 54 publications

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

Does more maternal investment mean a larger brain? Evolutionary relationships between reproductive mode and brain size in chondrichthyans

Brooding fathers, not siblings, take up nutrients from embryos

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