Early ontogeny of Labeotropbeus Ahl, 1927 (Mbuna, Cichlidae, Lake Malawi), with a discussion on advanced protective styles in fish reproduction and development

Abstract

SynopsisWith yolk as a food source, development of Labeotropheus takes place in the buccal pouch of the female until such time as juveniles are formed. Hatching from the vitelline membrane occurs early, after 6 days of incubation, and the eleutheroembryo develops without metamorphic stages directly into a juvenile, forming advanced structures like tins, skeleton and pigments, at a time when a large yolksac is still present. A strong circulatory network on the yolk and anal fin fold, and a yellow carotenoid pigment provide the oxygen supply within the closely packed buccal pouch. A relatively large self-sufficient juvenile, 14% of the adult fish size, is released from the mother's mouth 31 days after fertilization. The evolution of advanced hiding styles in reproductive guilds of fishes is discussed and ends with a speculation that the Latimeria, having had more geological time to refine its hidine stvle. releases fullv developed young. 25 to 30% the -. , size of the adult fish. The advanced style -of hiding eggs is accompanied not only with fewer, larger eggs, but also by a successive increase in yolk density in terms of nutrients and respiratory pigments; these in effect determine the size of the released juvenile. 157

Heritability and adaptive significance of the number of egg-dummies in the cichlid fish Astatotilapia burtoni

“…Specifically, the large range of egg-spot number in A. burtoni, and some other species [14], means that there is likely to be considerable overlap in the number of egg-spots among many species, albeit males of some species always have a lower and more consistent egg-spot number [5,7,12]. Our results may therefore call for re-evaluation of eggspots as a species recognition cue, although we also note that it is still possible that the arrangement or appearance (such as size) of egg-spots is more species-specific than their number [5,7,8].…”

“…For example, in a natural breeding colony of A. burtoni, the number of egg-spots ranged between five and nine [13]. Similarly, sibling males of a Lake Malawi haplochromine species (Labeotropheus) were reported to have from two to six egg-spots [14]. This type of variation calls for an explanation, as traits important for successful fertilization, species recognition or fitness, in general, are expected to be under stabilizing selection, which should erode heritable genetic variation behind these traits (e.g.…”

Early development and allometric growth in Nannacara anomala Regan, 1905 (Perciformes: Cichlidae) under laboratory conditions

“…During this time, respiration was accomplished mainly through the body surface and the network of vessels present on the yolk sac and ventral fin fold. These temporary structures are characteristic for many fish species that lay eggs in lentic water bodies (Balon, 1975a;Meijide & Guerrero, 2000;Korzelecka-Orkisz et al, 2012) and have also been described in mouth-brooding species (Balon, 1975b(Balon, , 1977Holden & Bruton, 1994;Prusiñska et al, 2009).…”

The Structure and the Embryogenetic Role of Eggs and Egg Membranes of <I>Ancistrus Dolichopterus</I> (Actinopterygii: Siluriformes: Loricariidae)

“…Zona radiata of any species within the bony fishes is constructed of two layers: the thin external layer (zona radiata externa i.e., ZRE) and the thicker internal layer (zona radiata interna i.e., ZRI) (Balon 1977, Riehl 1991, Riehl and Patzner 1998. Modern technologies such as scanning electron microscopy (SEM), make it possible to find family-and species-specific variability in the thickness and structure of these layers.…”