Female fecundity traits in wild populations of African annual fish: the role of the aridity gradient

Abstract

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.

Community assembly inNothobranchiusannual fishes: Nested patterns, environmental niche and biogeographic history

“…Importantly, the altitudinal gradient in the study area coincides with a gradient of aridity where high‐altitude sites are significantly drier, with lower total rainfall, higher evapotranspiration rates, and lower predictability of rains (Terzibasi Tozzini et al., 2013; Vrtílek & Reichard, 2016b). The coastal plains are more humid, with temporary pools inundated for a longer period (Blažek et al., 2017; Terzibasi Tozzini et al., 2013).…”

The role of energetic reserves during embryonic development of an annual killifish

“…Larger hatchling size decreases gape limitation and allows fish to capture larger variety of prey during the initial phase of natural pool succession (Meintjes, ). In Nothobranchius spp., increased food intake greatly enhances growth rate (Vrtílek and Reichard, ) and, consequently, promotes more rapid maturation (Blažek et al, ). This may be crucial for successful reproduction in ephemeral habitats where desiccation risk is imminent.…”

“…The parents of the experimental embryos were F2 generation of the strain founders, imported from southern Mozambique in 2013. Vrtílek and Reichard () have demonstrated natural interpopulation variability in N. furzeri egg size. Hence, we specifically chose to use individuals from the large‐egg‐producing population 414 (collection code MZCS 414, GPS: S22 ° 33′ 16.7″, E32 ° 43′ 38.1″; 12 wild‐caught pairs imported) and the small‐egg‐producing population 422 (collection code MZCS 422, GPS: S22 ° 06′ 37.0″, E33 ° 46′ 28.7 ″; 15 wild‐caught pairs imported).…”

Costly defense in a fluctuating environment—sensitivity of annual Nothobranchius fishes to predator kairomones

“…At the same time, in southern Mozambique the very incidence of the pools, duration of the wet phase, and their repeated filling are subject to great interannual and regional fluctuations (Mazuze, ; Blažek et al., ; Terzibasi et al. , Reichard et al., ; Vrtílek and Reichard , Blažek et al. ).…”