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Life after death: When does your phenotype expire?

Throughout an organisms’ life, the expression of genes, regulated by the biotic and abiotic environment, gives rise to traits that determine how fast it can run or how tall it can grow. Many traits also affect species interactions; for example, are you fast enough to outrun predators? Do you look tasty to herbivores? Most traits (e.g., running speed) cease to be important once an organism dies, but some traits linger and have “afterlife” effects on the environment. A prominent example of afterlife effects can be found in decomposing plant material, which is a crucial part of nutrient cycling. Microbes and fungi are critical to many stages of nutrient cycling, such as the mineralization of organic matter and the nitrification of NH4+, which plants cannot use, to NO3, which is usable by plants. However, microbes and fungi can be “picky eaters” in a sense, as they prefer substrates with labile simple sugars instead of defensive molecules such as lignin. Simple sugars have carbon and nitrogen supplies that are easily accessible, while larger, more complex molecules require degradation by energetically-costly enzymes. Therefore, genetic and environmental influences on the chemical composition of plant material can persist after a plant sheds its leaves and affect how quickly its nutrients are cycled.

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