Developmental ecology of annual killifish Millerichthys robustus (Cyprinodontiformes: Cynolebiidae)

Abstract

Populations of annual killifishes persist in temporary water bodies over the dry season through the expression of diapause in their drought-resistant embryos. Environmental cues may influence expression of the diapause phenotype during embryonic incubation. Millerichthys robustus is the only annual killifish distributed in North America. The aim of this review is to analyze the ecology of M. robustus development and contrast this with that of annual killifishes in austral locations. The temporary water bodies inhabited by M. robustus present the following environmental conditions: flood, drought, and humidity. During the flooding period, the environment presents the lowest temperatures, shortest photoperiod, and highest precipitation, and embryos were found in diapause I. The drought period features the highest temperatures and lowest precipitation, and embryos were found in diapause II. In contrast, during the humid period at the beginning of the rainy season, embryos were found in diapause I, II, and III, associated with the longer photoperiod and high temperatures. These dynamics of the diapause phenotypes can be explained by a combination of the strategies of phenotypic plasticity during flood and drought periods, and bet-hedging during the humid period. Moreover, the microenvironmental conditions in which embryos were buried could influence developmental trajectories. Developmental Dynamics 246:802-806, 2017. © 2017 Wiley Periodicals, Inc.

Reproductive biology of annual killifishes and its relationship with embryonic survival during diapause: Millerichthys robustus (Cyprinodontiformes: Cynolebiidae) as an integrative model

“…The above because were not observed embryos in more advanced stages of development than somitogenesis or diapause III before the humidity period. Another study found embryos in diapause I and III simultaneously during humid period (Domínguez‐Castanedo et al., ). Diapause skipping was not documented in any of the previous research; however, it is common under controlled conditions (Domínguez‐Castanedo, pers.…”

“…The chorion of the M. robustus embryos (Figure d) was described using a light microscope as hair‐like filaments located on the distal tip of mushroom‐like projections in an almost regularly distributed pattern on the verrucate surface (Domínguez‐Castanedo et al., ). However, the scanning electron microscopy reveal that chorion is formed by long hair‐like filaments located on the distal tip of projections of the egg surface and rounded protuberances uniformly distributed in a verrucate pattern (Figure e,f).…”

“…Annual killifishes inhabit temporary water bodies in Africa and America that present extreme climate changes due to unpredictable rainy seasons (Berois, Arezo, Papa, & Clivio, ; Murphy & Collier, ). The only genus of American annual killifish who developed an annual life history in North America is Millerichthys , in which only a single species is known to date: Millerichthys robustus endemic to southeast of México (Domínguez‐Castanedo, Mosqueda‐Cabrera, & Valdesalici, ; Loureiro & de Sá, ; Miller, ; Miller & Hubbs, ).…”

“…Research on M. robustus has been directed in document how this species developed its annual life history isolated in the North America (Domínguez‐Castanedo et al., ; Domínguez‐Castanedo, Uribe, & Rosales‐Torres, , ; Domínguez‐Castanedo, Rosales‐Torres, & Uribe, ; Domínguez‐Castanedo, Valdesalici, Domínguez‐Castanedo, & Mosqueda‐Cabrera, ); allowing us to consider to M. robustus as an emerging model for annual killifishes to review, analyze and integrate the elements of reproductive biology involved in allowing the embryos in diapause to survive face the hostile environmental conditions; identifying the proper elements of this species and those shared with other annual fish species. Also, it is therefore important to conduct integrative morphophysiological approaches that elucidates this species and its interaction with the environment, considering its management and conservation (Wikelski & Cooke, ).…”

Ovarian structure, folliculogenesis and oogenesis of the annual killifish Millerichthys robustus (Cyprinodontiformes: Cynolebiidae)

“…Annual killifishes inhabit temporal water bodies in ecosystems of Africa, South America (Myers, ; Peters, ; Huber, ; Costa, ) and Mexico (Domínguez‐Castanedo, Mosqueda‐Cabrera, & Valdesalici, ). In Mexico, only the presence of one species of annual fish is known: Millerichthys robustus , endemic of ecosystems that present extreme and erratic climatic changes in the drainages of the rivers Papaloapan and Coatzacoalcos, in Veracruz and Oaxaca States (Miller & Hubs, ).…”