Habitat-Specific Clock Variation and Its Consequence on Reproductive Fitness

Abstract

The circadian clock controls daily activities at the cellular and organismic level, allowing an organism to anticipate incoming stresses and to use resources accordingly. The circadian clock has therefore been considered a fitness trait in multiple organisms. However, the mechanism of how circadian clock variation influences organismal reproductive fitness is still not well understood. Here we describe habitat-specific clock variation (HSCV) of asexual reproduction in Neurospora discreta, a species that is adapted to 2 different habitats, under or above tree bark. African (AF) N. discreta strains, whose habitat is above the tree bark in light-dark (LD) conditions, display a higher rhythmicity index compared with North American (NA) strains, whose habitat is under the tree bark in constant dark (DD). Although AF-type strains demonstrated an overall fitness advantage under LD and DD conditions, NA-type strains exhibit a habitat-specific fitness advantage in DD over the LD condition. In addition, we show that allelic variation of the clock-controlled gene, Ubiquinol cytochrome c oxidoreductase (NEUDI_158280), plays a role in HSCV by modulating cellular reactive oxygen species levels. Our results demonstrate a mechanism by which local adaptation involving circadian clock regulation influences reproductive fitness.

Identification and expression of functionally conserved circadian clock genes in lichen-forming fungi

“…In plants, the circadian clock aligns chemical defenses to herbivore feeding patterns, regulates drought responses, and anticipates pathogen attack (see Xu et al 2022 17 for a recent review of the role of the circadian clock in plant biotic and abiotic stress responses). In fungi, the asexual reproductive patterns of Neurospora crassa have long been observed to be regulated by the circadian clock 18 , 19 , while strains of Neurospora discreta with habitat-specific circadian rhythms maintain higher fitness in their respective habitats 20 .The interacting circadian clocks in symbiotic systems are a growing topic of interest 21 , 22 . Tightly-regulated circadian systems have been observed between corals and algae 23 , 24 , as well as between the Hawaiian bobtail squid Euprymna scolopes and the bioluminescent bacteria Vibrio fischeri 25 .…”

The circadian clock controls temporal and spatial patterns of floral development in sunflower

“…For example, studies in humans show the timing of drug treatment can be critical to creating an effective therapeutic response (Ruan et al, 2021). A functioning circadian clock whose biological rhythms match that of the environment provides a fitness advantage for many organisms, including plants (Dodd et al, 2005;Michael et al, 2003), animals (Miller et al, 2004;Emerson et al, 2008;Spoelstra et al, 2016), bacteria (Ouyang et al, 1998), and fungi (Koritala et al, 2020). One important way the circadian clock promotes fitness is by controlling timing of reproductive development, for example by allowing organisms to distinguish between the long and short days of different seasons.…”

The circadian clock controls temporal and spatial patterns of floral development in sunflower

“…For example, studies in humans show the timing of drug treatment can be critical to creating an effective therapeutic response (Ruan et al, 2021). A functioning circadian clock whose biological rhythms match that of the environment provides a fitness advantage for many organisms, including plants (Dodd et al, 2005;Michael et al, 2003), animals (Miller et al, 2004;Emerson et al, 2008;Spoelstra et al, 2016), bacteria (Ouyang et al, 1998), and fungi (Koritala et al, 2020).…”