Transgenerational response to early spring warming in Daphnia

Abstract

Temperature and photoperiod regulate key fitness traits in plants and animals. However, with temperature increase due to global warming, temperature cue thresholds are experienced at shorter photoperiods, disrupting the optimal seasonal timing of physiological, developmental and reproductive events in many species. Understanding the mechanisms of adaptation to the asynchrony between temperature and photoperiod is key to inform our understanding of how species will respond to global warming. Here, we studied the transgenerational mechanisms of responses of the cyclical parthenogen Daphnia magna to different photoperiod lengths co-occurring with warm temperature thereby assessing the impact of earlier spring warming on its fitness. Daphnia uses temperature and photoperiod cues to time dormancy, and to switch between sexual and asexual reproduction. Daphnia life cycle offers the opportunity to measure the relative contribution of plastic and genetic responses to environmental change across generations and over evolutionary time. We use transgenerational common garden experiments on three populations ‘resurrected’ from a biological archive experiencing temperature increase over five decades. Our results suggest that response to early spring warming evolved underpinned by a complex interaction between plastic and genetic mechanisms while a positive maternal contribution at matching environments between parental and offspring generation was also observed.

Environmental variation mediates the evolution of anticipatory parental effects

“…2005; Toyota et al. 2019), annelids (Jensen et al. 2014), and herbs (Galloway and Etterson 2007), it is also been found in fish in which the generation time span is in years (Ryu et al.…”

“…2018; Toyota et al. 2019). Because transgenerational effects should evolve only if parents can accurately predict offspring environments (Kuijper and Hoyle 2015; Leimar and McNamara 2015; Uller et al.…”

“…2018; Toyota et al. 2019), but across studies there is only weak support for this prediction in natural systems, and the effects are small compared to the direct effects of offspring environment (reviewed in Uller et al. 2013).…”

Combined salinity and acidity stressors alterDaphnia magnapopulation growth and structure under severe absence of photoperiod

“…It can be argued that delayed maturation is a plastic trait governed by maternal preconditioning of offspring phenotype [9,10,105], akin to diapause, i.e. , resting [28], which will favour survival rather than reproduction in adverse environmental conditions. This may be beneficial when accompanied by the ability of the preconditioned neonates to alter their ionic and osmotic regulation [8].…”

“…The duration and intensity of light exposure can have a strong influence on many organisms and research on zooplankton has studied effects on diapause [24,25]; egg hatching [26], circadian clock, diel vertical migration [27] and ontogenesis [28] in response to photoperiod and light quantity [29]. Somewhat surprisingly then, investigations of the effect of exposure to elevated light at night, constant light, or lack of light, on plastic responses of zooplankton in general, and D. magna in particular, has been overlooked for decades except for the area of diapause and sexual morph production [25], and alteration of their phototaxis [30].…”