Temporary pools are seasonal wetland habitats with specifically adapted biota, including annual Nothobranchius killifishes that survive habitat desiccation as diapausing eggs encased in dry sediment. To understand the patterns in the structure of Nothobranchius assemblages and their potential in wetland conservation, we compared biodiversity components (alpha, beta, and gamma) between regions and estimated the role and sources of nestedness and turnover on their diversity. We sampled Nothobranchius assemblages from 127 pools across seven local regions in lowland Eastern Tanzania over 2 years, using dip net and seine nets. We estimated species composition and richness for each pool, and beta and gamma diversity for each region. We decomposed beta diversity into nestedness and turnover components. We tested nestedness in three main regions (Ruvu, Rufiji, and Mbezi) using the number of decreasing fills metric and compared the roles of pool area, isolation, and altitude on nestedness. A total of 15 species formed assemblages containing 1-6 species. Most Nothobranchius species were endemic to one or two adjacent regions. Regional diversity was highest in the Ruvu, Rufiji, and Mbezi regions. Nestedness was significant in Ruvu and Rufiji, with shared core (N. melanospilus, N. eggersi, and N. janpapi) and common (N. ocellatus and N. annectens) species, and distinctive rare species. Nestedness apparently resulted from selective colonization rather than selective extinction, and local species richness was negatively associated with altitude. The Nothobranchius assemblages in the Mbezi region were not nested, and had many endemic species and the highest beta diversity driven by species turnover. Overall, we found unexpected local variation in the sources of beta diversity (nestedness and turnover) within the study area. The Mbezi region contained the highest diversity and many endemic species, apparently due to repeated colonizations of the region rather than local diversification. We suggest that annual killifish can serve as a flagship taxon for small wetland conservation.

• Klíčová slova
• Africa, Cyprinodontiformes, dispersal, ephemeral habitats, habitat protection,
• Publikační typ
• časopisecké články MeSH

Dietary alteration is one of the most universally effective aging interventions, making its standardization a fundamental need for model organisms in aging. In this dietetic study we address the current lack of standardized formulated diet for turquoise killifish Nothobranchius furzeri - a promising model organism. We first demonstrated that N. furzeri can be fully weaned at the onset of puberty onto a commercially available pelleted diet as the sole nutrition when kept in social tanks. We then compared nine somatic and six reproductive parameters between fish fed a typical laboratory diet - frozen chironomid larvae (bloodworms) and fish weaned from bloodworms to BioMar pellets. Both dietary groups had comparable somatic and reproductive performance. There was no difference between diet groups in adult body size, specific growth rate, condition or extent of hepatocellular vacuolation. Fish fed a pelleted diet had higher juvenile body mass and more visceral fat. Pellet-fed males had lower liver mass and possessed a lipid type of hepatocellular vacuolation instead of the prevailing glycogen-like vacuolation in the bloodworm-fed group. No considerable effect was found on reproductive parameters. The negligible differences between dietary groups and good acceptance of pellets indicate their suitability as a useful starting point for the development of standardized diet for Nothobranchius furzeri.

• MeSH
• chov zvířat normy   MeSH
• dieta normy   veterinární   MeSH
• Fundulidae fyziologie   MeSH
• krmivo pro zvířata normy   MeSH
• modely u zvířat * MeSH
• složení těla MeSH
• stárnutí * MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Adaptive radiations are triggered by ecological opportunity - the access to novel niche domains with abundant available resources that facilitate the formation of new ecologically divergent species. Therefore, as new species saturate niche space, clades experience a diversity-dependent slowdown of diversification over time. At the other extreme of the radiation continuum, non-adaptively radiating lineages undergo diversification with minimal niche differentiation when 'spatial opportunity' (i.e. areas with suitable 'ancestral' ecological conditions) is available. Traditionally, most research has focused on adaptive radiations, while empirical studies on non-adaptive radiations remain lagging behind. A prolific clade of African fish with extremely short lifespan (Nothobranchius killifish), show the key evolutionary features of a candidate non-adaptive radiation - primarily allopatric species with minimal niche and phenotypic divergence. Here, we test the hypothesis that Nothobranchius killifish have non-adaptively diversified. We employ phylogenetic modelling to investigate the tempo and mode of macroevolutionary diversification of these organisms. RESULTS: Nothobranchius diversification has proceeded with minor niche differentiation and minimal morphological disparity among allopatric species. Additionally, we failed to identify evidence for a role of body size or biogeography in influencing diversification rates. Diversification has been homogeneous within this genus, with the only hotspot of species-richness not resulting from rapid diversification. However, species in sympatry show higher disparity, which may have been caused by character displacement among coexisting species. CONCLUSIONS: Nothobranchius killifish have proliferated following the tempo and mode of a non-adaptive radiation. Our study confirms that this exceptionally short-lived group have diversified with minimal divergent niche adaptation, while one group of coexisting species seems to have facilitated spatial overlap among these taxa via the evolution of ecological character displacement.

• Klíčová slova
• Diversification, Macroevolution, Non-adaptive radiation, Nothobranchius, Spatial opportunity, Speciation,
• MeSH
• biodiverzita * MeSH
• biologická evoluce * MeSH
• druhová specificita MeSH
• Fundulidae fyziologie   MeSH
• fylogeneze MeSH
• fylogeografie MeSH
• fyziologická adaptace * MeSH
• pravděpodobnostní funkce MeSH
• velikost těla MeSH
• vznik druhů (genetika) MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The turquoise killifish, Nothobranchius furzeri, is a promising vertebrate model in ageing research and an emerging model organism in genomics, regenerative medicine, developmental biology and ecotoxicology. Its lifestyle is adapted to the ephemeral nature of shallow pools on the African savannah. Its rapid and short active life commences when rains fill the pool: fish hatch, grow rapidly and mature in as few as two weeks, and then reproduce daily until the pool dries out. Its embryos then become inactive, encased in the dry sediment and protected from the harsh environment until the rains return. This invertebrate-like life cycle (short active phase and long developmental arrest) combined with a vertebrate body plan provide the ideal attributes for a laboratory animal.

• Klíčová slova
• Ageing, Natural History, Nothobranchius furzeri, Senescence, The Natural History of Model Organisms, Turquoise killifish, ecology, evolutionary biology,
• MeSH
• Cyprinodontiformes genetika   růst a vývoj   fyziologie   MeSH
• dieta MeSH
• ekosystém * MeSH
• embryo nesavčí fyziologie   MeSH
• modely u zvířat MeSH
• pigmentace MeSH
• sexuální chování zvířat MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The natural history of model organisms is often overlooked despite its importance to correctly interpret the outcome of laboratory studies. Ageing is particularly understudied in natural populations. To address this gap, we present lifetime demographic data from wild populations of an annual species, the turquoise killifish, Nothobranchius furzeri, a model species in ageing research, and two other species of coexisting annual killifishes. Annual killifish hatch synchronously, have non-overlapping generations, and reproduce daily after reaching sexual maturity. Data from 13 isolated savanna pools in southern Mozambique demonstrate that the pools supporting killifish populations desiccated 1-4 months after their filling, though some pools persisted longer. Declines in population size over the season were stronger than predicted, because they exceeded the effect of steady habitat shrinking on population density that, contrary to the prediction, decreased. Populations of N. furzeri also became more female-biased with progressing season suggesting that males had lower survival. Nothobranchius community composition did not significantly vary across the season. Our data clearly demonstrate that natural populations of N. furzeri and its congeners suffer strong mortality throughout their lives, with apparent selective disappearance (condition-dependent mortality) at the individual level. This represents selective force that can shape the evolution of lifespan, and its variation across populations, beyond the effects of the gradient in habitat persistence.

• MeSH
• Cyprinodontiformes * genetika   fyziologie   MeSH
• dlouhověkost MeSH
• ekosystém MeSH
• hustota populace MeSH
• longitudinální studie MeSH
• poměr pohlaví MeSH
• populační dynamika MeSH
• roční období MeSH
• sympatrie MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The assembly of local communities from regional species pools is shaped by historical aspects of distribution, environmental conditions, and biotic interactions. We studied local community assembly patterns in African annual killifishes of the genus Nothobranchius (Cyprinodontiformes), investigating data from 168 communities across the entire range of regionally co-existing species. Nothobranchius are small fishes associated with annually desiccating pools. We detected a nested pattern of local communities in one region (Southern Mozambique, with Nothobranchius furzeri as the core and dominant species), but no nestedness was found in the second region (Central Mozambique, with Nothobranchius orthonotus being the dominant species). A checkerboard pattern of local Nothobranchius community assembly was demonstrated in both regions. Multivariate environmental niche modeling revealed moderate differences in environmental niche occupancy between three monophyletic clades that largely co-occurred geographically and greater differences between strictly allopatric species within the clades. Most variation among species was observed along an altitudinal gradient; N. furzeri and Nothobranchius kadleci were absent from coastal plains, Nothobranchius pienaari, Nothobranchius rachovii, and Nothobranchius krysanovi were associated with lower altitude and N. orthonotus was intermediate and geographically most widespread species. We discuss implications for ecological and evolutionary research in this taxon.

• Klíčová slova
• Africa, altitudinal gradient, checkerboard pattern, dispersal, ephemeral pools, temporary water body,
• Publikační typ
• časopisecké články MeSH

The evolution of life history is shaped by life expectancy. Life-history traits coevolve, and optimal states for particular traits are constrained by trade-offs with other life-history traits. Life histories contrast among species, but may also diverge intraspecifically, at the level of populations. We studied the evolution of female reproductive allocation strategy, using natural populations of two sympatric species of African annual fishes, Nothobranchius furzeri and Nothobranchius orthonotus. These species inhabit pools in the Mozambican savanna that are formed in the rainy season and persist for only 2-10 months. Using 207 female N. furzeri from 11 populations and 243 female N. orthonotus from 14 populations, we tested the effects of genetic background (intraspecific lineage) and life expectancy (position on the aridity gradient determining maximum duration of their temporary habitat) on female fecundity traits. First, we found that variation in female body mass was small within populations, but varied considerably among populations. Second, we found that fecundity was largely defined by female body mass and that females spawned most of their eggs in the morning. Third, we found that the trade-off between egg size and egg number varied among lineages of N. furzeri and this outcome has been confirmed by data from two separate years. Overall, we demonstrate that local conditions were important determinants for Nothobranchius growth and fecundity and that eggs size in arid region was less limited by female fecundity than in humid region.

• Klíčová slova
• Annual killifish, egg size, interpopulation variation, intrapopulation variability, life expectancy, reproductive allocation,
• Publikační typ
• časopisecké články MeSH

Turquoise killifish, Nothobranchius furzeri, have an intrinsically short life span, with a median life span of <6 months and a maximum (90%) life span of 9 months. This short life span, which is unique among vertebrates, evolved naturally and has resulted in N. furzeri becoming a widely used laboratory model species in aging research and other disciplines. Here, we describe a protocol for the maintenance and breeding of the species under laboratory conditions. We provide details for egg incubation, hatching, everyday care of juvenile and adult fish, breeding and treatment of most common diseases. Emphasis is given to the fact that the requirements of N. furzeri substantially differ from those of other fish model taxa; N. furzeri live brief lives and in nature undergo nonaquatic embryo development, with consequences for their laboratory culture.

• MeSH
• chov metody   MeSH
• Cyprinodontiformes genetika   fyziologie   MeSH
• dlouhověkost MeSH
• laboratoře * MeSH
• nemoci ryb terapie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Extreme environmental conditions can give rise to extreme adaptations. We document growth, sexual maturation and fecundity in two species of African annual fish inhabiting temporary savanna pools. RESULTS: Nothobranchius kadleci started to reproduce at the age of 17 days and size of 31 mm and Nothobranchius furzeri at 18 days and 32 mm. All four study populations demonstrated rapid growth rates of up to 2.72 mm/day (23.4% of their total length). Both species may produce diapausing embryos or embryos that are able to hatch in as few as 15 days, resulting in a minimum generation time as short as only one month. Incubation on the surface of damp peat moss results in high embryo survival (73%) and a high proportion of rapidly developing embryos (58%) that skip diapauses and hatch in less than 30 days. We further demonstrated that rapid growth and maturation do not compromise subsequent fecundity. CONCLUSIONS: Our data suggest that both species have the most rapid sexual maturation and minimum generation time of any vertebrate species, and that rapid maturity does not involve paedogenesis.

• Publikační typ
• časopisecké články MeSH

BACKGROUND: Interspecific reproductive isolation is typically achieved by a combination of intrinsic and extrinsic barriers. Behavioural isolating barriers between sympatric, closely related species are often of primary importance and frequently aided by extrinsic factors causing spatial and temporal interspecific separation. Study systems with a severely limited role of extrinsic factors on reproductive isolation may provide valuable insights into how reproductive isolation between sympatric species is maintained. We used no-choice experimental set-up to study reproductive barriers between two closely related sympatric African killifish species, Nothobranchius furzeri and Nothobranchius orthonotus. These fish live in small temporary savannah pools and have complete spatial and temporal overlap in reproductive activities and share a similar ecology. PRINCIPAL FINDINGS: We found that the two species display largely incomplete and asymmetric reproductive isolation. Mating between N. furzeri males and N. orthonotus females was absent under standard experimental conditions and eggs were not viable when fish were forced to mate in a modified experimental setup. In contrast, male N. orthonotus indiscriminately mated with N. furzeri females, the eggs were viable, and offspring successfully hatched. Most spawnings, however, were achieved by male coercion and egg production and embryo survival were low. Behavioural asymmetry was likely facilitated by mating coercion from larger males of N. orthonotus and at relatively low cost to females. Interestingly, the direction of asymmetry was positively associated with asymmetry in post-mating reproductive barriers. SIGNIFICANCE: We showed that, in fish species with a promiscuous mating system and multiple matings each day, selection for strong mate preferences was relaxed. This effect was likely due to the small proportion of resources allocated to each single mating and the high potential cost to females from mating refusal. We highlight and discuss the fact that males of rarer species may often coercively mate with females of a related, more abundant species.

• MeSH
• Fundulidae fyziologie   MeSH
• rozmnožování fyziologie   MeSH
• sexuální chování zvířat fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH