The influence of environmental instability on the reproductive strategy of the critically endangered Acıgöl killifish (Aphanius transgrediens)

Abstract

To investigate the variability in the reproductive tactics of Acıgöl killifish (Aphanius transgrediens), one of the most seriously threatened freshwater teleost species, this study compared its reproductive ecology in two contrasting habitats that differ substantially in terms of stability of environmental parameters, particularly salinity regime (stable vs. unstable). Fish were sampled monthly from October 2013 to September 2014 with the aim of testing whether the reproductive life-history response of fish to stable and unstable conditions differed. The reproductive effort (gonad weight) of both sexes did not differ significantly between the two habitats, but females in the unstable habitat had significantly lower fecundity and larger eggs. The relationship between fecundity and fish size was stronger in the stable habitat, whereas the relationship was quite variable and uncertain in the unstable habitat. Fish born in the unstable habitat reached their first maturity at a smaller size than those in the stable habitat. The gonado-somatic index and the duration of hydrated eggs showed that reproduction continued from February to May in both habitats; nonetheless, a second spawning event occurred during July and August in the unstable habitat, which included the reproductive contributions of YOY individuals and older generations. This study's results suggest that A. transgrediens employs varying reproductive strategies against environmental instability in its restricted unique range. This may have further implications for the ways in which habitat-specific conservation methods are used.

Identification and characterization of miRNAs and target genes response to hypoosmotic adaption in the cobia, Rachycentron canadum

“…Salinity stress responses can bring a variety of effects on organism, including growth, osmotic regulation, organ development, reproduction and immune response (Bertucci et al, 2017;Lin et al, 2020;Wang et al, 2018;Yoğurtçuoğlu et al, 2020). The osmoregulation of euryhaline teleost response to salinity stress was mediated via multiple processes, including the activation of branchial ion channels and ionocytes, participation of transporters, secretion of endocrine hormones, rapid clearance of damaged macromolecules and modulation the mRNA expression levels of salinity-related genes (Vij et al, 2020).…”

“…Salinity is a major abiotic factor that has significant effects on growth and development, reproduction, and physiology of many aquatic organisms (Bertucci et al, 2017;Wang et al, 2018;Yoğurtçuoğlu et al, 2020). The changes in environmental salinity can lead to hypo-and hyper-osmotic modulation, which arouses a series of physiological responses to habitat water with different osmotic regulation parameter.…”

A preliminary analysis of the population genetic parameters indicates critically low genetic variation in a threatened killifish ( Anatolichthys transgrediens )

“…Several factors could explain this observation. Firstly, A. transgrediens has long been suffering from critical population decline since the early 90s, at least to the best of available literature (Wildekamp et al, 1999;Yoğurtçuoğlu et al, 2020). Secondly, the species has an incredibly small distribution range in a closed basin, which might have constituted an impediment to range expansion through dispersal (Wildekamp et al, 1999;Yoğurtçuoğlu & Ekmekçi, 2014).…”

“…All these springs flood the lowland and form wetland patches in between the fault lines and the lake itself (Figure 1). Individuals of A. transgrediens occur within these patchy habitats, some of which are hydrologically isolated, but some are known to become connected during seasons of high rain intensity that enable fish to move and disperse across the wetland (Wildekamp et al, 1999;Yoğurtçuoğlu et al, 2020). To the best of our knowledge, the species had been widespread in the northern side of the lake until the 80s (Grimm, 1979(Grimm, , 1980, but has vanished from that side and remained within several springs in the southern side (Wildekamp et al, 1999).…”

“…To the best of our knowledge, the species had been widespread in the northern side of the lake until the 80s (Grimm, 1979(Grimm, , 1980, but has vanished from that side and remained within several springs in the southern side (Wildekamp et al, 1999). Today, only one group of reproductively active adult individuals were reported from a spring in the northern side of the lake (Yoğurtçuoğlu et al, 2020), yet, no data is available on whether they are isolated from the southern springs. Therefore, we treat our samples as subpopulations of A. transgrediens i.e.…”