Embryonic development of the annual killifish Austrofundulus limnaeus: An emerging model for ecological and evolutionary developmental biology research and instruction

Abstract

Background: Austrofundulus limnaeus is an annual killifish from the Maracaibo basin of Venezuela. Annual killifishes are unique among vertebrates in their ability to enter into a state of dormancy at up to three distinct developmental stages termed diapause I, II, and III. These embryos are tolerant of a wide variety of environmental stresses and develop relatively slowly compared with nonannual fishes. Results: These traits make them an excellent model for research on interactions between the genome and the environment during development, and an excellent choice for developmental biology laboratories. Furthermore, A. limnaeus is relatively easy to maintain in a laboratory setting and has a high fecundity, making it an excellent candidate as an emerging model for studies of development, and for defining the limits of developmental buffering in vertebrates. Conclusions: This study reports for the first time on the detailed development of A. limnaeus and provides a photographic and illustrated atlas of embryos on the two developmental trajectories possible in this species. Developmental Dynamics 246:779-801, 2017. V C 2017 Wiley Periodicals, Inc.

Killifish eggs can disperse via gut passage through waterfowl

“…1D) that are not closely related but coexist in the Coastal Plain of Rio Grande do Sul, Brazil (31°17 0 S; 51°5 0 W), where droppings with a fish egg and chorions were previously found. The experimental eggs were in diapause I (600 eggs) or diapause II (50 eggs of A. minuano) developmental stages (Podrabsky et al 2017) that are the most frequent for eggs collected in the field (Reichard and Pola cik 2019). We mixed the eggs into a standard 120-g ration of corn-based food provided to three captive coscoroba swans in the Parque Zool ogico da Fundac ßão Zoobotânica do Rio Grande do Sul (PZFZB) and allowed them to feed on it during a period of 4 h (7:00-11:00 a.m.).…”

“…The eggs of annual killifish, including our study species, are well adapted to harsh conditions (Reichard and Pola cik 2019). The life cycle of annual killifish includes a period when the entire population resides in desiccated sediment of their natal pools as embryos protected in the eggs with a thick chorion (Podrabsky et al 2017). At this stage, the embryos are protected in diapause II (Reichard and Pola cik 2019) with their metabolic rates reduced by 90%, and are insensitive to a harsh external environment (Podrabsky and Hand 1999).…”

Egg size does not universally predict embryonic resources and hatchling size across annual killifish species

“…At each inspection, we 182 removed dead embryos and recorded the date of those reaching the pre-hatching developmental 183 stage, i.e. the "golden-eye" stage (Stage 5 in Varela-Lasheras and Van Dooren (2014), St. 43 in 184 Podrabsky et al (2017)). We kept the pre-hatching stage embryos in their wells until the scheduled 185 hatching date.…”

The evolution of diapause in Rivulus (Laimosemion)

“…Killifish that are adapted to life in temporary bodies of water are found across large portions of Africa, South America (Murphy & Collier, 1997;Cellerino, Valenzano & Reichard, 2016;Furness, 2016) and Mexico (Dominguez-Castanedo, Mosqueda-Cabrera & Valdesalici, 2013). Owing to the regular or periodic drying of their aquatic habitat, certain species have evolved desiccation-resistant eggs capable of undergoing diapause at specific embryological stages (Wourms, 1972a, b, c;Podrabsky et al, 2017). As their aquatic environments dry out and the adults die, the developing eggs remain buried in the soil in diapause until the next rainy season.…”