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Abstract Sex is a crucial process that has molecular, genetic, cellular, organismal, and population‐level consequences for eukaryotic evolution. Eukaryotic life cycles are composed of alternating haploid and diploid phases but are constrained by the need to accommodate the phenotypes of these different phases. Critical gaps in our understanding of evolutionary drivers of the diversity in algae life cycles include how selection acts to stabilize and change features of the life cycle. Moreover, most eukaryotes are partially clonal, engaging in both sexual and asexual reproduction. Yet, our understanding of the variation in their reproductive systems is largely based on sexual reproduction in animals or angiosperms. The relative balance of sexual versus asexual reproduction not only controls but also is in turn controlled by standing genetic variability, thereby shaping evolutionary trajectories. Thus, we must quantitatively assess the consequences of the variation in life cycles on reproductive systems. Algae are a polyphyletic group spread across many of the major eukaryotic lineages, providing powerful models by which to resolve this knowledge gap. There is, however, an alarming lack of data about the population genetics of most algae and, therefore, the relative frequency of sexual versus asexual processes. For many algae, the occurrence of sexual reproduction is unknown, observations have been lost in overlooked papers, or data on population genetics do not yet exist. This greatly restricts our ability to forecast the consequences of climate change on algal populations inhabiting terrestrial, aquatic, and marine ecosystems. This perspective summarizes our extant knowledge and provides some future directions to pursue broadly across micro‐ and macroalgal species.
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The Tree of Sex consortium: a global initiative for studying the evolution of reproduction in eukaryotes
Abstract: Reproduction is a fundamental aspect of life that affects all levels of biology, from genomes and development to population dynamics and diversification. The first Tree of Sex database synthesized a vast diversity of reproductive strategies and their intriguing distribution throughout eukaryotes. A decade on, we are reviving this initiative and greatly expanding its scope to provide the most comprehensive integration of knowledge on eukaryotic reproduction to date. In this perspective, we first identify important gaps in our current knowledge of reproductive strategies across eukaryotes. We then highlight a selection of questions that will benefit most from this new Tree of Sex project, including those related to the evolution of sex, modes of sex determination, sex chromosomes, and the consequences of various reproductive strategies. Finally, we outline our vision for the new Tree of Sex database and the consortium that will create it (treeofsex.org). The new database will cover all Eukaryota and include a wide selection of biological traits. It will also incorporate genomic data types that were scarce or non-existent at the time of the first Tree of Sex initiative. The new database will be publicly accessible, stable, and self-sustaining, thus greatly improving the accessibility of reproductive knowledge to researchers across disciplines for years to come. Lastly, the consortium will persist after the database is created to serve as a collaborative framework for research, prioritizing ethical standards in the collection, use, and sharing of reproductive data. The new Tree of Sex consortium is open, and we encourage all who are interested in this topic to join us.
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- Award ID(s):
- 2127995
- PAR ID:
- 10612492
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Journal of Evolutionary Biology
- ISSN:
- 1420-9101
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The relative frequency of sexual versus asexual reproduction governs the distribution of genetic diversity within and among populations. Most studies on the consequences of reproductive variation focus on the mating system (i.e., selfing vs. outcrossing) of diploid‐dominant taxa (e.g., angiosperms), often ignoring asexual reproduction. Although reproductive systems are hypothesized to be correlated with life‐cycle types, variation in the relative rates of sexual and asexual reproduction remains poorly characterized across eukaryotes. This is particularly true among the three major lineages of macroalgae (green, brown, and red). The Rhodophyta are particularly interesting, as many taxa have complex haploid–diploid life cycles that influence genetic structure. Though most marine reds have separate sexes, we show that freshwater red macroalgae exhibit patterns of switching between monoicy and dioicy in sister taxa that rival those recently shown in brown macroalgae and in angiosperms. We advocate for the investigation of reproductive system evolution using freshwater reds, as this will expand the life‐cycle types for which these data exist, enabling comparative analyses broadly across eukaryotes. Unlike their marine cousins, species in the Batrachospermales have macroscopic gametophytes attached to filamentous, often microscopic sporophytes. While asexual reproduction through monospores may occur in all freshwater reds, the Compsopogonales are thought to be exclusively asexual. Understanding the evolutionary consequences of selfing and asexual reproduction will aid in our understanding of the evolutionary ecology of all algae and of eukaryotic evolution generally.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/jeb/voaf053
