Reproduction, larviculture and early development of the Bluebanded goby,Lythrypnus dalli,an emerging model organism for studies in evolutionary developmental biology and sexual plasticity

Abstract

The Bluebanded goby, Lythrypnus dalli, is a popular ornamental aquarium species and a key organism for the study of several fundamental biological questions, most notably reversible sex change in adults. To maximize the tractability of this species as an emerging model system, it is essential to have an optimized propagation system and a detailed developmental staging scheme. One limitation to the larviculture of L. dalli is the relatively small size of the larvae, which makes the transition from yolk to feeding challenging. We developed a protocol and successfully reared three generations of L. dalli in the laboratory. The protocol contains several key innovations for the rearing of diminutive fish larvae, including tank design and co‐culturing of microalgae (Isochrysis galbana) with copepods (Parvocalanus sp.) in the larval rearing tanks. In addition, we describe the embryonic and larval development of L. dalli under controlled conditions and in comparison with the model organism Danio rerio. We found that at 21°C L. dalli larvae hatch in 4 days, reach flexion in 18–25 days and are sexually mature by 3 months. Overall, the embryonic development of L. dalli is remarkably similar to D. rerio with several striking differences, including the position and shape of the blastomere, size of the neuromasts and corresponding cupula, and relative timing of pigmentation and brain subdivision. The ability to rear this species in captivity is a valuable tool that could be utilized for a variety of similarly diminutive species and to address a greater breadth and depth of biological questions.

Ancestral androgenic differentiation pathways are repurposed during the evolution of adult sexual plasticity

“…Although the function of the two chambers (Fig. 3) within the GP of L. dalli remains unknown, preliminary evidence suggests that the ventral chamber in males has a blind end and likely is utilized to hydrostatically stiffen the genitalia to facilitate sperm and mucus transfer to the nest surface (Archambeault et al 2015). The dorsal chamber in males likely releases sperm embedded in proteins as well as mucus synthesized in the malespecific accessory gonadal structure (Archambeault et al 2015).…”

“…3) within the GP of L. dalli remains unknown, preliminary evidence suggests that the ventral chamber in males has a blind end and likely is utilized to hydrostatically stiffen the genitalia to facilitate sperm and mucus transfer to the nest surface (Archambeault et al 2015). The dorsal chamber in males likely releases sperm embedded in proteins as well as mucus synthesized in the malespecific accessory gonadal structure (Archambeault et al 2015). Accordingly, we show that males exhibit increased expression of AR and 11b-HSD2 in the ventral epithelium relative to females, suggesting that androgenic signaling regulates the release of sperm and mucus in males.…”

“…Unlike other goby species, L. dalli eggs within the female ovary lack the adhesive threads that are used for attachment to the substrate (Tavolga 1950). Accordingly, these filaments must be added during transport of the egg from the ovary to the substrate (Archambeault et al 2015). Given its anatomy and location, the ventral chamber in female genitalia is most likely the source of the adhesive threads in this species (Fig.…”

Year‐round natural spawning, early development, and the effects of temperature, salinity and prey density on captive ornate gobyIstigobius ornatus(Rüppell, 1830) larval survival

“…Fertilized eggs were sampled from artificial caves with a cover slip and dropper. Morphological descriptions generally followed the terminology of Kimmel, Ballard, Kimmel, Ullmann, and Schilling () and Archambeault et al (). The eggs were observed and photographed using a Canon EOS 600D digital SLR camera mounted on a Leica DMLB stereomicroscope.…”

“…Fishes of the family Gobiidae have great potential for the aquarium trade because of their diverse colours, peaceful behaviours and ease of domestication and adaptation to commercial feed and home aquaria (Darcy, ; Olivotto et al, ; Shei, Mies, & Olivotto, ). Recent years have seen increased attention given to the study of reproduction, morphology and larval rearing of marine ornamental gobies compared with the past (Archambeault et al, ; Majoris, Franciscoa, Atemaa, & Buston, ; Meirelles, Tsuzuki, Ribeiro, Medeiros, & Silva, ; Olivotto et al, ; Pedrazzani, Pham, Lin, & Neto, ; Sunobe, ; Wittenrich, Turingan, & Creswell, ).…”