Animal-microbial symbioses in changing environments

Abstract

The environments in which animals have evolved and live have profound effects on all aspects of their biology. Predictable rhythmic changes in the physical environment are arguably among the most important forces shaping the evolution of behavior and physiology of animals, and to anticipate and prepare for these predictable changes animals have evolved biological clocks. Unpredictable changes in the physical environment have important impacts on animal biology as well. The ability of animals to cope with and survive unpredictable perturbations depends on phenotypic plasticity and/or microevolution. From the time metazoans first evolved from their protistan ancestors they have lived in close association with a diverse array of microbes that have influenced, in some way, all aspects of the evolution of animal structure, function and behavior. Yet, few studies have addressed whether daily or seasonal rhythms may affect, or be affected by, an animal’s microbial symbionts. This survey highlights how biologists interested in the ecological and evolutionary physiology of animals whose lifestyles are influenced by environmental cycles may benefit from considering whether symbiotic microbes have shaped the features they study.

Seasonal shifts in the insect gut microbiome are concurrent with changes in cold tolerance and immunity

“…Insects that overwinter in temperate environments are exposed to low temperatures for prolonged periods (Williams et al, 2015), and undergo profound seasonal changes in feeding (Hahn & Denlinger, 2007), gut contents (Olsen & Duman, 1997;Olsen, Sass, Li, & Duman, 1998), immunity (Ferguson & Sinclair, 2017) and physiology (Denlinger & Lee, 2010). Because the composition of the microbiome depends on the physiological state of the host (Douglas, 2015), these seasonal changes in host physiology are also likely to influence the composition of the gut microbiome (Carey & Duddleston, 2014). Further, because the microbiome may differ depending on diet (Franzini et al, 2016;Maes, Rodrigues, Oliver, Mott, & Anderson, 2016;Wang, Gilbreath, Kukutla, Yan, & Xu, 2011), seasonal changes in food or microbiota in the external environment likely contribute to changes in the insect microbiome (Ludvigsen et al, 2015).…”

The Costs of Living Together: Immune Responses to the Microbiota and Chronic Gut Inflammation

“…Diet seems to be a strong driver of microbiota community structure on individual, population, and species levels (72,77,(115)(116)(117)(118)(119)(120). The diet of animals can vary considerably between habitats and seasons, and the vertebrate gut microbiota can strongly influence host metabolism, nutrition, and the inflammatory state of the gut (121)(122)(123)(124)(125)(126). Changes in diet are associated with chronic gut inflamma-tion in mice, humans, and fish (54,127,128).…”

“…For animals, changes in food type and availability are common (129)(130)(131). Both of these could affect the microbiota and the host's immune response (34,126).…”

Metabolic programming of the epigenome: host and gut microbial metabolite interactions with host chromatin

“…The natural shifts in microbial communities observed in hibernators may also be driven by the marked changes in body temperature, but the effects of body temperature independent of changes in feeding behavior and metabolic depression on microbial community dynamics remain poorly defined. During torpor when body temperatures are lower than 10ºC, microbes have limited metabolic and proliferative activity while IBAs provide brief periods of rewarming and microbial proliferation, particularly for those species capable of degrading and utilizing host-derived compounds (216). These large shifts in temperature during torpor-arousal cycles do not appear to cause extinction of summer-active populations.…”