Transgenerational Variation in Metabolism and Life-History Traits Induced by Maternal Hypoxia inDaphnia magna

Abstract

Hypoxic stress can alter conspecific phenotype and additionally alter phenotypes of the filial generation, for example, via maternal or epigenetic processes. Lasting effects can also be seen across development and generations even after stressors have been removed. This study utilized the model of rapidly developing, parthenogenetic Daphnia to examine the intraspecific variability of response of exposure of a parental generation to hypoxia (4 kPa) within a single clone line across development, across broods, and across generations. Body mass across development and reproductive output were monitored in the parental generation and the first three broods of the first filial generation (which were not directly exposed to hypoxia). O(2) consumption across a wide Po(2) range (normoxia to anoxia) was assessed to determine whether exposure of the parental generation to hypoxia conferred hypoxia tolerance on the offspring and whether this transgenerational, epigenetic phenomenon varied intraspecifically. Differences in mass occurred in both the parental generation (hypoxia-exposed smaller during brood 1 and brood 2 neonate production) and the filial generation (e.g., brood 1 and 2 neonates from hypoxic mothers were initially smaller than control neonates). However, differences in mass were not accompanied by changes in reproductive output (assessed by brood number and neonate size). At day 0, first filial generation brood 1 neonates from hypoxia-exposed mothers had a higher metabolic rate than control neonates. However, this effect, like that of body mass, dissipated with development within a brood but also with subsequent broods. An isometric scaling exponent for [Formula: see text] was repeatedly observed across a wide Po(2) range (21-2 kPa) throughout neonatal development.

Challenges and opportunities in developmental integrative physiology

“…In addition, molecular or cellular changes following environmental changes that arise through developmental phenotypic plasticity or epigenetic alterations may not be reflected in whole organismal phenotypic change, so care must be taken when arriving at definitive conclusions regarding effects of environmental perturbations. Lastly, clonal animals may reduce variation across treatments within an experiment (Andrewartha and Burggren, 2012; Verhoeven and Preite, 2013), and animals capable of regenerating from portions of their whole bodies ( e.g. starfish, flatworms) may be animal models that can provide unique insights into transgenerational physiological inheritance.…”

“…Animals that can reproduce clonally by asexual reproduction ( e.g. the water flea Daphnia ) can help eliminate complexities introduced across generations by genetic variation in offspring (Andrewartha and Burggren, 2012; Verhoeven and Preite, 2013). Animals that can regenerate major portions of their body when bi- or dissected ( e.g.…”

Can environmental conditions experienced in early life influence future generations?

“…from the gamete stage until the point when individuals began the maturation process) of the parental generation and then measured offspring phenotypes for one or more generations. Correlative epidemiological studies are excluded.environmental manipulation during parental development (F 0 )offspring generations affectedeffect on offspringspeciesreferencesplants salt and heat stressF 1 time of flowering, salt tolerance Arabidopsis [18] heavy metal exposureF 2 heavy metal tolerancerice[19]arthropods temperatureF 1 sizebutterfly[20] nutrition levelF 1 sizesoil mite[21] dietary compositionF 2 –F 3 foraging strategy, population growth rate and carrying capacityflour beetle[22] nutrition levelF 1 growth, development rate, immunitybutterfly[23] dietary compositionF 1 size, development ratefruit fly[24] dietary compositionF 1 development rate, reproductive output, nutrient metabolismfruit fly[25] hypoxiaF 1 size, metabolic ratewater flea[26]fishes nutrition levelF 1 size, growthcichlid[…”

Dynamics of epigenetic phenomena: intergenerational and intragenerational phenotype ‘washout’

“…intragenerational changes in DNA methylation with development, growth and senescence, as discussed below. Our laboratory has collected preliminary evidence for intragenerational washout of epigenetic phenotypic modifications evident in the body morphology of the water flea Daphnia magna (Andrewartha and Burggren, 2012), which is emerging as a promising model for epigenetic studies (Harris et al, 2012). We exposed adult female D. magna to hypoxia (4%) for 6 days (Fig.…”