Extreme asynchrony in embryo development, a typical feature of annual killifish living in temporary pools, represents a bet-hedging strategy to cope with unpredictable rainfall. African annual killifish are distributed across a large precipitation gradient, raising the potential for local adaptation in the degree of developmental asynchrony (e.g. higher in arid areas, lower in humid areas). Eight populations of two sister species, Nothobranchius furzeri and Nothobranchius kadleci, from sites along the rainfall gradient were tested and compared for asynchrony and duration of embryo development. Degree of asynchrony and mean duration of embryo development did not differ across the examined range. Despite generally high developmental variability, fish from more arid regions (where rain is more erratic) produced a significantly higher proportion of short-developing embryos. Comparable developmental asynchrony, regardless of precipitation level, suggests that all populations tested need to cope with some level of rainfall stochasticity. By producing more short-developing embryos, however, fish in more arid areas with relatively more erratic rains are better adapted to very short pool durations and are more likely to produce multiple offspring generations within a single rainy season.

• MeSH
• biologická adaptace * MeSH
• Cyprinodontidae růst a vývoj   MeSH
• Cyprinodontiformes MeSH
• déšť * MeSH
• embryonální vývoj * MeSH
• roční období MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Mosambik MeSH

Ephemeral habitats can impose challenging conditions for population persistence. Survival strategies in these environments can range from high dispersal capacity to the evolution of dormant stages able to tolerate a harsh environment outside the temporal window of favourable conditions [1]. Annual killifish have evolved to live in seasonal pools on the African savannah and display a range of adaptations to cope with an unpredictable environment [2,3]. For most of the year, killifish populations survive as diapausing embryos buried in dry sediment. When savannah depressions fill with rainwater, the fish hatch, grow rapidly and, after attaining sexual maturity, reproduce daily [2,4]. Nothobranchius furzeri, a model species in ageing research [2,3], is distributed in a region where the climate is particularly dry and rains are unpredictable [5]. Here, we demonstrate that the fast juvenile growth and rapid sexual maturation shown by N. furzeri in captivity is actually an underestimate of their natural developmental rate. We estimated the age of N. furzeri in natural populations by counting daily-deposited increments in the otoliths and performing histological analysis of gonads. We found that N. furzeri are capable of reaching sexual maturity within 14 days after hatching, which to our knowledge is the fastest rate of sexual maturation recorded for a vertebrate. We also demonstrate that N. furzeri can grow from an initial length of 5 mm up to 54 mm over the course of a two-week period. Such rapid juvenile development is likely to be adaptive since some pools were entirely desiccated 3-5 weeks after filling, but retained a viable killifish population that reproduced before the adults succumbed to the disappearance of their pool.

• MeSH
• Cyprinodontiformes růst a vývoj   fyziologie   MeSH
• déšť MeSH
• ekosystém * MeSH
• fyziologická adaptace MeSH
• pohlavní dospělost * MeSH
• rozmnožování MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• dopisy MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Mosambik MeSH

We tested the effect of population density on maximum body size in three sympatric species of annual killifishes Nothobranchius spp. from African ephemeral pools. We found a clear negative effect of population density on body size, limiting their capacity for extremely fast development and rapid growth. This suggests that density-dependent population regulation and the ephemeral character of their habitat impose contrasting selective pressures on the life history of annual killifishes.

• MeSH
• Cyprinodontiformes růst a vývoj   MeSH
• ekosystém MeSH
• Fundulidae růst a vývoj   fyziologie   MeSH
• hustota populace MeSH
• roční období MeSH
• sexuální faktory MeSH
• věkové rozložení MeSH
• velikost těla * fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Afrika MeSH
• Mosambik MeSH

In ephemeral habitats, the same genotypes cope with unpredictable environmental conditions, favouring the evolution of developmental plasticity and alternative life-history strategies (ALHS). We tested the existence of intrapopulation ALHS in an annual killifish, Nothobranchius furzeri, inhabiting temporary pools. The pools are either primary (persisting throughout the whole rainy season) or secondary (refilled after desiccation of the initial pool), representing alternative niches. The unpredictable conditions led to the evolution of reproductive bet-hedging with asynchronous embryonic development. We used a common garden experiment to test whether the duration of embryonic period is associated with post-embryonic life-history traits. Fish with rapid embryonic development (secondary pool strategy, high risk of desiccation) produced phenotypes with more rapid life-history traits than fish with slow embryonic development (primary pool strategy). The fast fish were smaller at hatching but had larger yolk sac reserves. Their post-hatching growth was more rapid, and they matured earlier. Further, fast fish grew to a smaller body size and died earlier than slow fish. No differences in fecundity, propensity to mate or physiological ageing were found, demonstrating a combination of plastic responses and constraints. Such developmentally related within-population plasticity in life history is exceptional among vertebrates.

• MeSH
• analýza přežití MeSH
• ekosystém * MeSH
• fenotyp MeSH
• fertilita fyziologie   MeSH
• Fundulidae embryologie   růst a vývoj   fyziologie   MeSH
• rybníky MeSH
• velikost těla fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Afrika MeSH

Seven ephemeral pools on the coastal plain of southern Brazil were found to be inhabited by three annual and 22 non-annual fish species. Two common annual species (Austrolebias minuano and Cynopoecilus fulgens) exhibited clear seasonal dynamics, with the appearance of young fishes in the austral autumn (May to June) and a decline in abundance over the seasonal cycle. The third annual species, Austrolebias wolterstorffii, was rare. No seasonal dynamics were observed in non-annual fishes. The relative abundance of non-annual fishes compared with annual fishes increased over the seasonal cycle, but they coexisted widely. The size structure of annual fishes suggested the presence of a single age cohort in most pools though a second age cohort was registered in one pool in August, coinciding with a large flooding. Strong sexual dimorphism in body size was found in C. fulgens throughout the seasonal cycle, while no sexual dimorphism in body size was found in A. minuano. Female-biased sex ratios were recorded in both common annual fish species in the last three sampling dates (in spring), but not during the first two sampling dates (in winter). The natural lifespan of annual fishes was <8 months. Annual fishes disappeared before habitat desiccation in half of the pools, while non-annual fishes were still present.

• MeSH
• Cyprinodontiformes * MeSH
• ekosystém MeSH
• hustota populace MeSH
• pohlavní dimorfismus MeSH
• poměr pohlaví * MeSH
• roční období * MeSH
• ryby MeSH
• velikost těla * MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Brazílie MeSH

BACKGROUND: Intraspecific genetic variation of African fauna has been significantly affected by pronounced climatic fluctuations in Plio-Pleistocene, but, with the exception of large mammals, very limited empirical data on diversity of natural populations are available for savanna-dwelling animals. Nothobranchius furzeri is an annual fish from south-eastern Africa, inhabiting discrete temporary savannah pools outside main river alluvia. Their dispersal is limited and population processes affecting its genetic structure are likely a combination of those affecting terrestrial and aquatic taxa. N. furzeri is a model taxon in ageing research and several populations of known geographical origin are used in laboratory studies. Here, we analysed the genetic structure, diversity, historical demography and temporal patterns of divergence in natural populations of N. furzeri across its entire distribution range. RESULTS: Genetic structure and historical demography of N. furzeri were analysed using a combination of mitochondrial (partial cytochrome b sequences, 687 bp) and nuclear (13 microsatellites) markers in 693 fish from 36 populations. Genetic markers consistently demonstrated strong population structuring and suggested two main genetic groups associated with river basins. The split was dated to the Pliocene (>2 Mya). The northern group inhabits savannah pools across the basin of the intermittent river Chefu in south-western Mozambique and eastern Zimbabwe. The southern group (from southernmost Mozambique) is subdivided, with the River Limpopo forming a barrier (maximum divergence time 1 Mya). A strong habitat fragmentation (isolated temporary pools) is reflected in significant genetic structuring even between adjacent pools, with a major influence of genetic drift and significant isolation-by-distance. Analysis of historical demography revealed that the expansion of both groups is ongoing, supported by frequent founder effects in marginal parts of the range and evidence of secondary contact between Chefu and Limpopo populations. CONCLUSIONS: We demonstrated: (1) ancient (pre-Pleistocene) divergence between the two main N. furzeri lineages, their recent secondary contact and lack of reproductive isolation; (2) important genetic structuring attributed to the fragmented nature of their environment and isolation-by-distance, suggesting that dispersal is limited, occurs over short distances and is not directly associated with river routes; (3) an apparent role of the River Limpopo as a barrier to dispersal and gene flow.

• MeSH
• Cyprinodontiformes klasifikace   genetika   MeSH
• cytochromy b genetika   MeSH
• ekosystém MeSH
• fylogeneze MeSH
• genetická variace MeSH
• mitochondriální DNA genetika   MeSH
• populační genetika MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Mosambik MeSH

• Publikační typ
• abstrakt z konference 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

The age structures of populations of African annual Nothobranchius spp. were examined for the first time. Daily increments in sagittal otoliths of Nothobranchius furzeri, Nothobranchius kadleci, Nothobranchius orthonotus and Nothobranchius rachovii from southern and central Mozambique were used for age determination. Four hypotheses were tested: (1) timing of hatching is consistent with the calendar onset of the rainy season, (2) hatching is synchronized within a population in a pool, (3) there is a difference in hatching date between geographical regions differing in mean total annual precipitation and (4) sympatric Nothobranchius spp. hatch at the same time. The results show that daily increment analysis represents an applicable method for age determination in Nothobranchius spp. Despite a significant positive relationship between age and size of fishes, a pronounced variation in fish size at an age precluded the use of fish size as a valid age marker. Timing of hatching was not consistent with the calendar onset of the rainy season. Interpopulation variability was observed in the degree of hatching date synchronization within a population. Hatching dates were relatively uniform in some populations, while there was considerable variability in others. Differences in timing of hatching date were found in only 1 of 2 years within the three regions investigated (Chefu, lower Limpopo and Sofala regions), each of which differed in mean total annual rainfall. The hatching dates of sympatric Nothobranchius spp. were marginally different, but further testing on a larger sample is needed for conclusive results.

• MeSH
• Cyprinodontidae fyziologie   MeSH
• otolitová membrána anatomie a histologie   MeSH
• roční období MeSH
• rozmnožování fyziologie   MeSH
• velikost těla fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Mosambik MeSH

BACKGROUND: Hatching is modulated by a combination of intrinsic and extrinsic factors. Annual killifish are adapted to complete their entire life cycle in annually desiccating habitats. Spending most of their life in the embryonic stage, they have evolved adaptations to survive desiccated conditions and match their hatching with the unpredictable onset of the aquatic phase of the pool. We examined spatial and temporal synchrony of hatching in natural populations of four species of African annual killifish (genus Nothobranchius). We compared differences and variability in hatching dates among years, regions, pools, and species and matched them with data on inundations of individual pools. RESULTS: Inundations typically coincided with peak rainfall in early January. We found considerable spatial and temporal synchrony in 1 year, but less synchrony in the other 2 years. Hatching generally occurred 0-20 days after inundation; fish at most sites hatched synchronously (<1 week) but some sites showed protracted hatching or two age cohorts. One species tended to hatch earlier than the other three. CONCLUSIONS: We suggest that hatching of annual killifish in the wild is a result of the interplay between environmental conditions and individual predisposition to respond to threshold environmental cues, ensuring effective bet-hedging against unpredictable inundation. Developmental Dynamics 246:827-837, 2017. © 2017 Wiley Periodicals, Inc.

• MeSH
• biologická variabilita populace * MeSH
• Cyprinodontiformes fyziologie   MeSH
• fyziologická adaptace * MeSH
• rozmnožování MeSH
• stadia vývoje * MeSH
• životní prostředí MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH