How Are Fungi Different From Animals And Plants
Have you ever picked upward something and wondered, "what is that?" Taxonomists help answer that question by dutifully documenting phenotypic (trait) and genotypic (genetic) differences among living things that permit them to be apace distinguished and identified. Placing organisms into categories is useful so that instead of describing a slew of characteristics, we can simply use wide categories as reference points to inform u.s.a. not but about the nature of an individual, but also almost its relationship to other similar organisms. A new organism classified as a vertebrate, for case, will exist unremarkably understood to have a spine composed of vertebrae. For scientists, taxonomic groups are touchstones of agreement: a foundation upon which to build new knowledge. This metaphor communicates the fundamental importance of taxonomy, but it implies a stability that taxonomic classification lacks.
For much of scientific history, fungi have been a botanist's domain. Until very recently — reasonably within a human being lifetime — fungi remained classified equally plants equally part of a centuries-former division that can be summed up by an axiom attributed to Carl Linnaeus: "Plants grow and live; Animals grow, live and feel." This "father of modern taxonomy" (and deviser of racist classifications of humans) classified living organisms into 2 categories: either animals or plants. This image tin can exist rephrased as animals and "not animals," equally the category "plants" long represented a canaille grouping of unrelated organisms. Without the context of evolution, these classifications sought to place organisms by perceived, oberservable similarity, instead of "relatedness" in a mod, genetic sense.
Classifying fungi every bit plants has led to some curious events. The earliest description of fungi pathogenic to insects (likely Cordyceps militaris) past the French entomologist René Antoine Ferchault de Réaumur was as a constitute root. The Mycological Social club of America was established while fungi were still considered plants, and the guild's journal Mycologia originated from the New York Botanical Garden. This garden continues to maintain ane of the earth's largest collections of fungi in their herbarium. This pairing of fungi with plants is a present problem: misclassification matters because how we allocate organisms affects how we understand, support (financially and culturally) and engage with them.
Why Were Fungi Ever Considered Plants?
Today, nosotros know that fungi are not plants, only the botanical history of fungi provides an interesting perspective on our scientific biases, on how nosotros allocate organisms and how these impact our collective knowledge.
Taxonomic classifications are in constant flux, as nosotros refine our understanding of the incredible multifariousness that surrounds us. Even in the age of genomics, we take only only scratched the surface of this diversity. Because we don't have a full picture of the diversity of life, our best laid classifications can be (and are) routinely shifted by a newcomer or fresh evidence. Today, nosotros take the luxury of molecular tools for classification, but taxonomic classifications can be traced back before the discovery of DNA, the concept of development and the invention of the microscope. Early classifications were limited by the tools (and views) available to them.
We must go along this caveat in mind when examining some of the early attempts at classifying life. Mushrooms were the earliest representatives of fungi to be classified. Based on observations of mushrooms, early taxonomists determined that fungi are immobile (fungi are not immobile) and they take rigid prison cell walls that support them. These characteristics were sufficient for early scientists to determine that fungi are not animals and to lump them with plants.
Reason 1: Fungi Lack Chloroplasts
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We accept arrived at our first reason fungi are not plants: fungi lack chloroplasts. This verdant, unifying feature of plants is readily appreciable to the eye, and these chlorophyll-containing plastids continue to be an important milestone for our modern understanding of found evolution. Of course, there are plants that lack functional chloroplasts, such as ghost pipes (Monotropa), but we know these flowering plants ("higher plants," once upon a time) lost chlorophyll during their evolutionary history. This evolutionary context was lacking until Darwin came forth, only demonstrates how callously uncooperative biology is with our bogus delineations. Broad outlines for our categories for living things were based on what nosotros could see, and microbes, including fungi without a fruiting body to observe, were an afterthought.
Reason 2: Fungi Accept a Unique Fashion of Acquiring Nutrients
Old paradigms for classifying life were so ingrained that challenging them was a difficult job. Still, the diverse groups of fungi provided scientists with a dainty tool for the task. In 1955, George Willard Martin challenged the notion that fungi should be classified as plants with an commodity titled "Are fungi plants?". In the introduction, he hazarded a estimate that nearly mycologists at the time would answer 'yes.' Still, his thorough examination of the topic influenced Robert Harding Whittaker in his pursuit to revolutionize taxonomy.
Whittaker published several articles proposing more kingdoms of life. He eventually settled on 5 kingdoms, but he was engaged in a philosophical, decades-long argue on the appropriate way to catalogue life. While a contemporary taxonomist Herbert Copeland argued for detailed description of features for classification informed past historical understanding, Whittaker advanced his theory based on ecology. Whittaker'due south theory was based on 3 types of ecological roles organisms can play: producers (photosynthesizers), consumers (eaters) and reducers (decomposers).
Arguably, Whittaker's reasoning finally extricated fungi from the kingdom of plants, and so information technology is our next reason fungi are not plants: fungi take a unique manner of acquiring nutrients. Fungi secrete digestive enzymes, then absorb nutrients from their surroundings. This is in sharp contrast to plants, which make their ain food (thank you to their chloroplasts). It was clear to Whittaker that this deviation distinguished fungi from plants ecologically, but he was too grappling with a more basic question: why are we classifying organisms? Is information technology improve to endeavor to unify organisms past evolutionary history than to separate them?
When the classification of living organisms was outset undertaken, nosotros believed the catalog could one twenty-four hour period exist complete. Whittaker knew that new editions of this catalog were produced each 24-hour interval, so instead of basing taxonomy on features alone, he argued for kingdoms that represented major evolutionary trajectories. These categories would be more useful for evolutionary and ecological questions. He published his textbook-ready v kingdom classification in 1969, which included separate fungal and institute kingdoms.
Reason 3: Molecular Evidence Demonstrates Fungi Are More Closely Related to Animals Than to Plants
The proposed separation of fungi and plants is indisputably supported by molecular evidence. Computational phylogenetics comparing eukaryotes revealed that fungi are more closely related to united states than to plants. Fungi and animals grade a clade called opisthokonta, which is named later a unmarried, posterior flagellum present in their last common ancestor. Today, this posterior flagellum propels archaic fungal spores and fauna sperm alike.
This is our terminal reason fungi are non plants: the best available molecular evidence demonstrates fungi are more closely related to animals than plants. These computational and molecular approaches are convincing because they provide robust evolutionary histories that indicate organismal relationships and guess when they diverged from mutual ancestors. A molecular understanding of life has uncovered 3 possible major domains of life: Bacteria, Archaea and Eukarya (nested within Archaea). These are distinguished by cellular components (due east.g., membrane-bound organelles) and the composition of the cell membrane.
Although they've been granted their ain kingdom, fungi continue to demand taxonomic attention. Molecular approaches reveal that mycologists have described some fungi more than than once. Various names for sexual (i.due east., producing mushrooms) and asexual forms of the aforementioned mucus have inspired an effort to revise fungal taxa, humbly called "One Name = One Mucus." This initiative continues today, but the challenge is immense, with databases like Index Fungorum list synonyms and citations with descriptions of fungi.
What has the (wrong) classification of mycology as a botanical pursuit washed to the advocacy of the field? The more than we know about fungi, the better prepared nosotros are to protect ourselves (and other organisms) from fungal infections. Fungi have so much to uniquely teach us well-nigh (to name simply 3 examples) evolution, ecology and cellular biology. Institute science departments proceed to train many mycologists across the land, but where would mycology be if this field of study were supported with a like number of departments? Would more microbiome studies explicitly include the mycobiome? Would nosotros exist better prepared for fungal threats to food security if the U.S. Department of Agronomics instead had a Animal, Plant *and Fungi* Wellness Protection Service? We have much to acquire almost fungi, but one thing is for certain: fungi are not plants.
Source: https://asm.org/Articles/2021/January/Three-Reasons-Fungi-Are-Not-Plants
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