Sex and Asex: A Clonal Lexicon

Abstract

Organisms across the tree of life have complex life cycles that include both sexual and asexual reproduction or that are obligately asexual. These organisms include ecologically dominant species that structure many terrestrial and marine ecosystems, as well as many pathogens, pests, and invasive species. We must consider both the evolution and maintenance of these various reproductive modes and how these modes shape the genetic diversity, adaptive evolution, and ability to persist of the species that exhibit them. Thus, having a common framework is a key aspect of understanding the biodiversity that shapes our planet. In the 2019 AGA President’s Symposium, Sex and Asex: The genetics of complex life cycles, researchers investigating a wide range of taxonomic models and using a variety of modes of investigation coalesced around a common theme – understanding not only how such complex life cycles may evolve, but how they are shaped by the evolutionary and ecological forces around them. In this introduction to the Special Issue from the symposium, we give an overview of some of the key ideas and areas of investigation (a common clonal lexicon, we might say) and introduce the breadth of work submitted by symposium participants.

Insufficient Sleep and Poor Sleep Quality Completely Mediate the Relationship between Financial Stress and Dietary Risk among Higher Education Students

“…The Spring 2019 National College Health Assessment reported more than one-third of college students stated that their finances had been traumatic or very difficult to handle during the past 12 months [ 6 ]. Unfortunately, the COVID-19 pandemic further worsened the financial situation for many students in higher education [ 7 , 8 ]. The National College Student COVID-19 Survey revealed that 30% of students reported losing a job needed to help pay for college, 77% of students reported that the pandemic reduced their ability to earn income to support their education, and 64% stated that their need for financial aid increased due to the pandemic [ 9 ].…”

Evolution via somatic genetic variation in modular species

“…Here, we focus on species with agametic formation of asexual offspring, often termed clonal reproduction, that has single or multiple cells of somatic tissue as precursors [15]. These species proliferate by producing new modules through diverse mechanisms such as budding, branching or fission (Figure 1), creating a population of ramets (a module existing as an independent physiological entity) belonging to a genet that dates back to a single zygote.…”

Detecting clonemates in multicellular clonal species based on “Shared Heterozygosity (SH)” and technical replicates

“…Clonal reproduction refers to the formation of new individuals that are genetically nearly identical to the parent via mitosis in the absence of genetic recombination (De Meeûs et al, 2007). This reproductive mode is widespread in multicellular organisms, and has many different forms, such as vegetative multiplication (animals and plants), parthenogenesis (animals), apomixis (plants), and gynogeneis or pseudogamy (De Meeûs et al, 2007; Orive & Krueger-Hadfield, 2021). In multicellular clonal species, a module or ramet (Harper & White, 1974) is the basic modular unit with an ability to live independently, while a genet (synonymous with clone) is the product of a single zygote from gamete fusion (Noble et al, 1979), and comprises all ramets that emerge via mitosis (i.e., clonemates) during its lifetime.…”