Sammendrag
Marine macrophytes are the foundation of algal forests and seagrass meadows–some
of the most productive and diverse coastal marine ecosystems on the planet. These
ecosystems provide nursery grounds and food for fish and invertebrates, coastline
protection from erosion, carbon sequestration, and nutrient fixation. For marine
macrophytes, temperature is generally the most important range limiting factor, and
ocean warming is considered the most severe threat among global climate change
factors. Ocean warming induced losses of dominant macrophytes along their equatorial
range edges, as well as range extensions into polar regions, are predicted and already
documented. While adaptive evolution based on genetic change is considered too
slow to keep pace with the increasing rate of anthropogenic environmental changes,
rapid adaptation may come about through a set of non-genetic mechanisms involving
the functional composition of the associated microbiome, as well as epigenetic
modification of the genome and its regulatory effect on gene expression and the activity
of transposable elements. While research in terrestrial plants demonstrates that the
integration of non-genetic mechanisms provide a more holistic picture of a species’
evolutionary potential, research in marine systems is lagging behind. Here, we aim to
review the potential of marine macrophytes to acclimatize and adapt to major climate
change effects via intraspecific variation at the genetic, epigenetic, and microbiome
levels. All three levels create phenotypic variation that may either enhance fitness
within individuals (plasticity) or be subject to selection and ultimately, adaptation. We review three of the most important phenotypic variations in a climate change context,
including physiological variation, variation in propagation success, and in herbivore
resistance. Integrating different levels of plasticity, and adaptability into ecological models
will allow to obtain a more holistic understanding of trait variation and a realistic
assessment of the future performance and distribution of marine macrophytes. Such
multi-disciplinary approach that integrates various levels of intraspecific variation, and
their effect on phenotypic and physiological variation, is of crucial importance for the
effective management and conservation of seagrasses and macroalgae under climate
change.
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