Mid-Miocene Formation of the Yangtze River-Lake System Revealed by Ancestral Spawning Reconstruction of Endemic Cyprinids

The Yangtze River is cross-linked with numerous lakes within its floodplain and is a worldwide biodiversity hotspot. There is no evidence indicating when this unique river-lake system developed. The endemic East Asian cyprinid clade has evolved diverse spawning adaptations to different flow conditions. Our ancestral egg-type reconstruction showed an ancestral state of adhesive eggs and later demersal eggs origination (both stream adaptations). Semi-buoyant eggs emerged ~18 Mya as a fast-flowing river adaptation, with increased hydration via three yolk protein degradation pathways, ion transport pathways and egg envelope permeability transition pores. Adhesive eggs evolved secondarily ~14 Mya with the egg envelope increasing to four layers and an adhesive layer, along with an increase in adhesiveness via microfilament/adhesive-related protein crosslinking and enhanced glycosaminoglycan biosynthesis, improving adherence to submerged lake plants, indicating that the cross-linked river-lake system formed in the mid-Miocene. This study provides a unique biological evidence for large-scale water system evolution.

Temporal variation in reproductive success and the effects of differential parental care on the progeny of fish with demersal eggs

A paternity test based on microsatellite analysis of eggs under the parental care of a bourgeois male Pacific sergeant major, Abudefduf troschelii, included gametes from five females and two parasitic males. The nest area was monitored for five days to evaluate variation in reproductive success, and an approximately 300% increase occurred on the first and second days after new oviposition followed by a more than 300% reduction from the second to fifth days due to predation or filial cannibalism. Finally, the egg area on the last day corresponded to the initial nest area, suggesting selective care by the male.

Nest-mediated parental care in a marine fish: Are large-scale nesting habitats selected and do these habitats respond to small-scale requirements?

Fishes have evolved various reproductive strategies including mechanisms that involve parental care and demersal eggs laid into nests. Symphodus ocellatus has a seasonal reproduction period during which large, dominant males become territorial and build nests with fragments of algae, where they attract females to spawn and provide care to the developing eggs. Based on the hypothesis that the S. ocellatus males choose the reproductive habitat based on some characteristics of the substrate, here we assessed whether, on a coastal area scale, the distribution of this species changes during the reproductive period because of the selection of some suitable sites or substrates, and whether the nesting microhabitat used by this species responding to certain requirements in relation to different characteristics. From April to September 2010, at four locations and on three substrate types, the fish were counted in three periods related to different stages of reproduction. Furthermore, several physical and biological variables have been recorded around numerous nests to select those with more recurrence. We found that S. ocellatus prefers to live on rocky substrates populated by photophilic algae, regardless of the phases of the reproductive cycle. We identified depth (1.7–3.2 m), the presence of a hole, a 10–20 cm algal canopy, and high algal coverage of Dyctiotales as nest requirements. S. ocellatus is mostly distributed in coastal sites sheltered from the action of waves. This allows the construction and maintenance of nests and the possibility to remain in a water temperature range similar to the reproductive physiological constraints.

Effects of reservoirs water level variations on fish recruitment

ABSTRACT The construction of hydroelectric power plants has many social and environmental impacts. Among them, the impacts on fish communities, which habitats are drastically modified by dams, with consequences across the ecosystem. This study aimed to assess the influence of water level (WL) variations in the reservoirs of the Itá and Machadinho hydroelectric plants on the recruitment of fish species from the upper Uruguay River in southern Brazil. The data analyzed resulted from the WL variation produced exclusively by the hydroelectric plants generation and were collected between the years 2001 and 2012. The results showed significant correlations between the abundance of juvenile fish and the hydrological parameters only for some reproductive guilds. The species that spawn in nests showed, in general, a clear preference for the stability in the WL of the reservoirs, while the species that spawn in macrophytes or that release demersal eggs showed no significant correlation between the abundance of juvenile fish and hydrological parameters. A divergence of results between the two reservoirs was observed between the species that release semi-dense eggs; a positive correlation with a more stable WL was only observed in the Machadinho reservoir. This result can be driven by a wider range of WL variation in Machadinho reservoir.

Not so sluggish: the success of theFelimare pictacomplex (Gastropoda, Nudibranchia) crossing Atlantic biogeographic barriers

The molecular phylogeny of the Atlanto-Mediterranean species of the genus Felimare, particularly those attributed to the speciesF. picta, was inferred using two mitochondrial markers (16S and COI). A recent revision of the Chromodorididae clarified the taxonomic relationships at the family level redefiningthe genusFelimare. However, conflicting taxonomic classifications have been proposed for a restrict group of taxa with overlapping morphological characteristics and geographical distributions designated here as theFelimare pictacomplex. Three major groups were identified: one Mediterranean and amphi-Atlantic group; a western Atlantic group and a tropical eastern Atlantic group.F. pictaforms a paraphyletic group since some subspecies are more closely related with taxa traditionaly classified as independent species (e.g.F. zebra) than with other subspecies with allopatric distributions (e.g.F. picta pictaandF. picta tema). Usually, nudibranchs have adhesive demersal eggs, short planktonic larval phases and low mobility as adults unless rafting on floating materials occurs. Surprisingly however, the phylogeny of theF. pictacomplex suggests that they successfully cross main Atlantic biogeographic barriers including the mid-Atlantic barrier. This ability to cross different biogeographic barriers may be related toF. picta’s distinct life history and ecological traits. Compared to other ChromodorididaeF. pictahas larger eggs and planktotrophic larvae which could be related to a longer planktonic phase.

Not so sluggish: the success of the Felimare picta complex (Gastropoda, Nudibranchia) crossing Atlantic biogeographic barriers

The molecular phylogeny of the Atlanto-Mediterranean species of the genus Felimare, particularly those attributed to the species F. picta, was inferred using two mitochondrial markers (16S and COI). A recent revision of the Chromodorididae clarified the taxonomic relationships at the family level reclassifying all eastern Pacific, Atlantic and Mediterranean species of the genus Hypselodoris and two species of the genus Mexichromis, within the genus Felimare. However, conflicting taxonomic classifications have been proposed for a group with overlapping morphological characteristics and geographical distributions designated here as the Felimare picta complex. Three major groups were identified: one Mediterranean and amphi-Atlantic group; a western Atlantic group and a tropical eastern Atlantic group. F. picta forms a paraphyletic group since some subspecies are more closely related with taxa traditionaly classified as independent species (e.g. F. zebra) than with other subspecies with allopatric distributions (e.g. F. picta picta and F. picta tema). Usually, nudibranchs have adhesive demersal eggs, short planktonic larval phases and low mobility as adults unless rafting on floating materials occurs. However, the phylogeny of the F. picta complex suggests they had an unusual success crossing main Atlantic biogeographic barriers including the mid-Atlantic barrier. This ability to cross different biogeographic barriers may be related with F. picta distinct life history and ecological traits. Compared to other Chromodorididae F. picta presents large eggs and planktotrophic larvae which could be related with a longer planktonic phase.

Not so sluggish: the success of the Felimare picta complex (Gastropoda, Nudibranchia) crossing Atlantic biogeographic barriers

The molecular phylogeny of the Atlanto-Mediterranean species of the genus Felimare, particularly those attributed to the species F. picta, was inferred using two mitochondrial markers (16S and COI). A recent revision of the Chromodorididae clarified the taxonomic relationships at the family level reclassifying all eastern Pacific, Atlantic and Mediterranean species of the genus Hypselodoris and two species of the genus Mexichromis, within the genus Felimare. However, conflicting taxonomic classifications have been proposed for a group with overlapping morphological characteristics and geographical distributions designated here as the Felimare picta complex. Three major groups were identified: one Mediterranean and amphi-Atlantic group; a western Atlantic group and a tropical eastern Atlantic group. F. picta forms a paraphyletic group since some subspecies are more closely related with taxa traditionaly classified as independent species (e.g. F. zebra) than with other subspecies with allopatric distributions (e.g. F. picta picta and F. picta tema). Usually, nudibranchs have adhesive demersal eggs, short planktonic larval phases and low mobility as adults unless rafting on floating materials occurs. However, the phylogeny of the F. picta complex suggests they had an unusual success crossing main Atlantic biogeographic barriers including the mid-Atlantic barrier. This ability to cross different biogeographic barriers may be related with F. picta distinct life history and ecological traits. Compared to other Chromodorididae F. picta presents large eggs and planktotrophic larvae which could be related with a longer planktonic phase.

Courtship behavior and spawning of the hairy blenny Labrisomus nuchipinnis (Labrisomidae) in southeastern Brazil

Labrisomus nuchipinnis is a diurnal bottom-dwelling sit-and-wait carnivorous fish that inhabits holes and rifts of rocky areas in tropical shallow waters. Here we report on the courtship behavior and spawning of this hairy blenny in southeastern Brazil, with a detailed description and comparison with other Blennioidei. Labrisomus nuchipinnis is a territorial species that was observed courting with more than one female, and presenting a well defined pattern cycle related to reproductive behavior and paternal egg care. Adhesive demersal eggs are laid on small algae-covered rocks at sites with increased current velocity within the male's territory, which may enable higher egg survivorship and shorter developmental time.