Patterns of morphological variation among populations of the widespread annual killifish Nothobranchius orthonotus are independent of genetic divergence and biogeography

Abstract

Populations of annual killifish of the genus Nothobranchius occur in patchily distributed temporary pools in the East African savannah. Their fragmented distribution and low dispersal ability result in highly structured genetic clustering of their populations. In this study, we examined body shape variation in a widely distributed species, Nothobranchius orthonotus with known phylogeographic structure. We tested whether genetic divergence of major mitochondrial lineages forming two candidate species is congruent with phenotypic diversification, using linear and geometric morphometry analyses of body shape in 23 wild populations. We also conducted a common-garden experiment with two wild-derived populations to control for the effect of local environmental conditions on body shape. We identified different allometric trajectories for different mitochondrial lineages and candidate species in both sexes. However, in a principal components analysis of population-level body shape, the separation among mitochondrial lineages was incomplete. Higher similarity of mitochondrial lineages belonging to different candidate species than that of same candidate species prevented distinction of the two candidate species on the basis of body shape. Analysis at the individual level demonstrated that N. orthonotus express high intrapopulation variability, with major overlap among individuals from all populations. In conclusion, we suggest that N. orthonotus be considered as a single species with an extensive geographic range, strong population genetic structure and high morphological variability.

Genetic diversity of a widespread annual killifish from coastal Tanzania

“…Importantly, the only mitochondrial lineage (Rufiji) with a significant support for its genetic distinctiveness from other N. melanospilus-species-group lineages coexist widely with the Ruvu lineage and nuclear markers did not indicate the lack of panmixia. The fact that two lineages that were formally described to represent cryptic species of the complexfrom the Wami (N. prognathus) and Ramisi (N. kwalensis)are less distinct than the Rufiji lineage apparently supports the arguments of Wildekamp [39], who regarded minor morphological differences between N. melanospilus sensu stricto and the two putative cryptic species as normal intraspecific variation commonly seen in this [39] and many other Nothobranchius species [16,40]. We acknowledge, however, that our results do not contradict existence of the two cryptic species either.…”

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

“…The ranges of the three clades overlap (Bartáková et al, 2015). One clade (the O-clade; Dorn et al, 2011;Bartáková et al, 2015) apparently includes a single, widely distributed species, Nothobranchius orthonotus (Peters) (Vrtílek & Reichard, 2016a). The F-clade (Bartáková et al, 2015;Dorn et al, 2011) consists of two morphologically well-defined species, Nothobranchius furzeri Jubb and Nothobranchius kadleci Reichard (Reichard, 2010).…”

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

“…The species co-occur syntopically throughout N. furzeri's range, with N. orthonotus range extending further northward (Fig. 2;Bart akov a et al 2015;Vrt ılek and Reichard 2016). Nothobranchius orthonotus occurs at lower population densities and attains larger asymptotic size than N. furzeri (Reichard et al 2009;as N. kuhntae in Genade et al 2005), although their ecological niche (habitat use and diet) largely overlaps (Pola cik and Reichard 2010;Pola cik et al 2014a).…”