SFB-TRR 212

Niche conformance in a holometabolous invertebrate: Adjustments of behavioural, physiological and chemical phenotypes and fitness consequences

Periods of starvation are very likely to occur in an insect’s lifetime in nature and may influence various traits of the individual. Early life starvation experience can have long-lasting effects on the development, but adults of some species are able to compensate for poor larval nutritional conditions, including starvation. In addition, poor nutrition or starvation, particularly early in life, affect behavioural phenotypes, making individuals, for example, more risk-prone. Thus, the timing of periods of starvation may be critical for shaping an individual’s phenotype. While the topic of so-called sensitive phases is well studied in vertebrates, less is known about their role in invertebrates.

Here, the sawfly A. rosae will be used to study the role of starvation in different developmental stages on life-history, metabolism, behaviour and the microbiome intra- and intergenerationally and thereby elucidate individualised niche conformance.

The main aims of this project are to elucidate mechanisms underlying individualised niche conformance and consequences thereof. Particular emphasis will be paid to the role of the critical time point at which an individual is exposed to a certain environment (i.e. starvation), to test for sensitive periods in an invertebrate. Furthermore, the functions, i.e. costs and benefits, of pharmacophagy in individualised niche conformance will be studied. Both aims will be combined by testing for potential interactive effects of starvation and pharmacophagy.

We will focus on the following topics:

1. Individualised niche conformance: mechanisms, consequences and timing
   1. Consequences of adult starvation periods on life-history, behaviour and metabolism
   2. Intragenerational: Effects of matching and mismatching conditions on life-history and metabolism
   3. Intergenerational: Effects of matching and mismatching conditions on life-history and microbiomes

Metabolism and behaviour are adjusted to enable individuals to adapt to food shortage, maintain homeostasis and recover from starvation. These adjustments depend on the phase in development at which starvation is experienced, allowing us to reveal potential sensitive phases in this insect species. In the microbiome, starvation-induced changes should be visible as part of the individualised niche. Both larval and adult starvation are predicted to have intergenerational effects on certain traits.

2. Functions of pharmacophagy
   1. Effects of clerodanoid uptake and starvation on adult life-history and behaviour
   2. Effects of clerodanoid uptake and starvation on adult metabolism
   3. Effects of clerodanoid uptake on the metabotype of adults and their microbiome
   4. Effects of clerodanoid uptake on resistance against entomopathogenic fungi

Clerodanoid uptake bears both costs (i.e., reduced longevity, higher risk of being involved in a fight for conspecific pharmacophagy) and benefits (i.e., reduced load of potentially adverse microbes, higher reproductive success). These may become more pronounced under starvation conditions.

Findings will promote our understanding of factors that shape individualised niche conformance across ontogeny.