Temperature-dependent life history and transcriptomic responses in heat-tolerant versus heat-sensitive Brachionus rotifers

Abstract

A species' response to thermal stress is an essential physiological trait that can determine occurrence and temporal succession in nature, including response to climate change. Environmental temperature affects zooplankton performance by altering life-spans and population growth rates, but the molecular mechanisms underlying these alterations are largely unknown. To compare temperature-related demography, we performed cross-temperature life-table experiments in closely related heat-tolerant and heat-sensitive Brachionus rotifer species that occur in sympatry. Within these same populations, we examined the genetic basis of physiological variation by comparing gene expression across increasing temperatures. We found significant cross-species and cross-temperature differences in heat response, with the heat-sensitive species adopting a strategy of high survival and low population growth, while the heat-tolerant followed an opposite strategy. Comparative transcriptomic analyses revealed both shared and opposing responses to heat. Most notably, expression of heat shock proteins (hsps) is strikingly different in the two species. In both species, hsp responses mirrored differences in population growth rates, showing that hsp genes are likely a key component of a species' adaptation to different temperatures. Temperature induction caused opposing patterns of expression in further functional categories such as energy, carbohydrate and lipid metabolism, and in genes related to ribosomal proteins. In the heat-sensitive species, elevated temperatures caused up-regulation of genes related to induction of meiotic division as well as genes responsible for post-translational histone modifications. This work demonstrates the sweeping reorganizations of biological functions that accompany temperature adaptation in these two species and reveals potential molecular mechanisms that might be activated for adaptation to global warming.

Reduced fertilization constitutes an important prezygotic reproductive barrier between two sibling species of the hybridizing Brachionus calyciflorus species complex

“…Our Papakostas et al, 2016;Paraskevopoulou et al, 2020Paraskevopoulou et al, , 2018Zhang et al, 2019). On the other hand, they support earlier conclusions that these species do hybridize (Lemmen et al, 2020;Papakostas et al, 2016) providing a plausible explanation for frequently observed mitonuclear discordances in field populations (Papakostas et al, 2016;Zhang et al, 2019).…”

Consequences of pharmacophagous uptake from plants and conspecifics in a sawfly elucidated using chemical and molecular techniques

“…However, it is becoming increasingly clear that this is not the case and that the expression of RPs can change in response to a number of different factors, e.g. heat stress (Paraskevopoulou et al, 2020) or the ingestion of ribosome-inactivating proteins (RIPs) contained in plant material (Celorio-Mancera et al, 2013;Stirpe, 2013). RPs also play numerous roles outside of ribosomal biogenesis (Zhou et al, 2015).…”

Intergenerational Effects of Early Life Starvation on Life-History, Consumption, and Transcriptome of a Holometabolous Insect

“…Larvae that were starved but whose parents were not starved may have suffered more than starved larvae from starved parents, as indicated by the upregulation of putative ribosomal pathway genes. Differential expression of genes of the ribosomal pathway has been observed in a wide variety of taxa in response to thermal stress (Paraskevopoulou et al 2020; Schwanz et al 2020; Srikanth et al 2020), demonstrating the broad role of this pathway in stress response. Differential expression of genes involved in stress and other physiological and metabolic responses may have energetic costs, which may lead to a prolonged development time of starved larvae in A. rosae .…”