News
What’s New in the Third Edition of Kingdoms of Life Connected? January 12 2023, 1 Comment
Last fall, I completed the third edition of my book, Kingdoms of Life Connected: A Teachers’ Guide to the Tree of Life. This came only six years after the second edition, which in turn came eight years after the first edition. “Why all this change?” you may ask.
I found that updates were needed because of changes in biologists’ view of the diversity of life. The data about how organisms are related continue to pour in, and because of this, the details of lineages and relationships change. You may be tempted to wait until the field stabilizes and stick with older ideas. Children, however, need a useful view of the diversity of life, even if it will be somewhat amended later. They cannot build on a foundation that is clearly obsolete. Specifically, it is no longer useful to present children with Five or Six Kingdoms, and those charts need to go in your history-of-science file.
I updated Kingdoms of Life Connected from cover to cover. I redid the lists of learning resources – books and websites; I purged links that no longer worked and added new ones. Publishers and authors have brought forth valuable new books in recent years, and I added titles to the lists while retaining older but useful books. I revised all the text, including the activities and lesson suggestions. I fact-checked the information to make sure it was as up to date as I could make it.
There is one especially important addition, a new lesson for introducing to the Tree of Life chart to beginning elementary children. This lesson gives older children important concepts as well, particularly if they have not yet had this overview. The introductory lesson leads children to the idea that all life shared a common ancestor and is connected. It shows them the relationships between the major branches of life. For example, they learn that the animals and fungi are sister lineages and that plants are only distantly related to fungi.
I’ll give a brief summary of some of the changes below. For more information, see the book, which is available at https://big-picture-science.myshopify.com/collections/biology/products/kingdoms-of-life-connected-third-edition (printed version). The ebook (pdf) is at https://big-picture-science.myshopify.com/collections/biology/products/kingdoms-of-life-connected-third-edition-ebook.
There are no big changes in the prokaryotes. I have kept a very basic approach because it takes extensive knowledge of biochemistry to understand the many branches of bacteria and archaea. Introductory college biology texts present a few basic lineages, and I felt that this approach would be good for children as well.
In the protists, I rearranged the Excavata lineage on the Tree of Life chart. Now, the euglenazoa and kinetoplastids are sister lineages and the metamonads are the first branch. I expect that Excavata will be split apart and redone in the future. It probably won’t be a eukaryotic supergroup, but studies continue to confirm the other supergroups – Archaeplastida, SAR, and Amorphea.
Scientific terminology evolves, and I was happy to see a complicated name go away. The branch of the stramenopiles and alveolates was previously called Chromalveolata, but that term has fallen out of favor. It originally described a lineage that included two branches I didn’t show, the cryptophytes and haptophytes; these are now placed elsewhere on the Tree of Life. The branch of the stramenopiles and alveolates may get a new name, but it seems best to leave that branch blank for now.
The fungi were the major branch that changed the most. The former Zygomycota lineage is now divided into two main lineages, the Mucoromycota and the Zoopagomycota. On my Tree of Life chart, I show the larger one, Murcoromycota. Its branches include the pin molds or Mucoromycotina (black bread mold, for example) and the arbuscular mycorrhiza fungi or Glomeromycotina (AM fungi). The AM fungi were previously placed on their own branch, but they have been added back to Mucoromycota. I didn’t add the Zoopagomycota to the Tree of Life chart, but if you have children who are interested in learning more, Fungarium by Katie Scott and Ester Gaya, is a good book for launching their explorations.
In the animal kingdom, studies have clarified some relationships in the protostome branch. You can give children the term “Spiralia” for the lineage previously called Lophotrochozoa. The whole branch is called Spiralia; “Lophotrochozoa” still refers to the mollusks and annelids. It is another of the situations where it is useful to know an older and newer term. “Lophotrochozoa” has been used for the Spiralia branch for about 20 years, and it appears in a number of websites. I recommend looking to the future and using “Spiralia” primarily. It is certainly easier to say and spell.
In the plant kingdom, studies have resolved several questions about the bryophytes. They are a single branch of life, a monophyletic lineage. The first branch was recently determined to be the hornworts. The mosses and liverworts are sister lineages. The older story was that the liverworts were the first branch because they do not have stomata. It appears that their ancestors lost their stomata rather than never having them.
The virus chapter now has suggestions for making a model of a coronavirus. I published this chapter as a stand-alone pdf in 2020. Note that if you have the third edition of Kingdoms of Life Connected, you already have the content of “What Is a Virus?”.
It is easy to become overwhelmed by all the names and branches of life. I recommend that you concentrate on the larger branches on the Tree of Life and continue to other branches as children (and you) learn about these and are interested in pursuing more. For in-depth studies at the elementary level, I recommend the digging further into the animal and plant kingdoms.
Start with the big overview of the Tree of Life. After that, my learning material, Sorting Branches on the Tree of Life: Vertebrates and Plants, is a good place to go. It is available as a pdf that you can print https://big-picture-science.myshopify.com/collections/biology/products/sorting-branches-on-the-tree-of-life-vertebrates-and-plants or as a printed material https://big-picture-science.myshopify.com/collections/biology/products/copy-of-sorting-branches-on-the-tree-of-life-vertebrates-and-plants-file-for-printing.
Enjoy your explorations of the Tree of Life!
How do you divide the eukaryotes? September 19 2019, 0 Comments
If I asked you how you would divide the eukaryotes into groups, what would you say? Many people would say protists, fungi, animals, and plants. This is the idea presented in Five (or Six) Kingdoms classification. There is a more enlightening way to divide the eukaryotes, one that students currently see in introductory college courses.
The DNA revolution and the development of systematics rather than plain classification have given us a new view. Systematics includes the relationships between taxonomic categories instead of listing them with no information about their shared ancestors. It is a young science that has produced many changes and will likely produce many more.
This is not to say that we don’t have useable information right now. The largest categories of eukaryotes have been defined, and they are called the eukaryotic supergroups. There are four of them presently, and so the eukaryotes can be divided into four groups. Here’s an introduction to the archaeplastida, SAR, excavata, and unikonts aka Amorphea.
Archaeplastida is the lineage that acquired the first chloroplast. Its name means “ancient plastids.” A plastid is a type of organelle in a eukaryotic cell, and the category includes the chloroplast, whose name means “green body.” The archaeplastida lineage includes red algae and green algae, along with the embryophytes or land plants, which evolved from a green alga. This lineage is the only one that incorporated an ancient cyanobacterium into its cells. The origin of the chloroplasts in other lineages is a more complicated story.
The SAR lineage is named for the three main branches within it, stramenopiles, alveolates, and rhizarians. These lineages were defined independently and then researchers gathered enough evidence to conclude that they share a common ancestor. The stramenopiles (aka chromists or heterokonts) include brown algae, golden algae, diatoms, and water molds. Alveolates include dinoflagellates, apicomplexans (parasites such as malaria), and ciliates. The rhizarians include foraminiferans and radiolarians, single cell organisms that build amazing outer shells called tests.
And where did these branches of life get their chloroplasts? It seems that chloroplasts are NOT easy to acquire. Apparently, it is easier to take one from another cell than to acquire one by eating a cyanobacterium. An ancestor of the stramenopiles and alveolates probably ate a red alga and kept its chloroplasts. Euglenas, which we meet below, got their chloroplasts from a green alga.
The third eukaryotic supergroup is the excavata, also called the excavates, but I see potential for confusion between the word as a noun vs. a verb. The lineage is named for a groove that looks like it has been excavated from the cells of some members. The excavata include the euglenas, which are free-living, and the trypanosomes, which are parasites. Other members of this group include the parasite Giardia and organisms that live in the guts of termites and help them break down cellulose. These have reduced mitochondria, so small that they were first described as lacking mitochondria.
I know you have been waiting for the last of the four supergroups, our own lineage, the unikonts (“single flagellum”) also known as the Amorphea (“having no form”). “Wait a minute,” you may be thinking, “we definitely have form.” The amoebas that belong to this lineage do not, however. The Amoebozoa lineage includes most of the slime molds or social amoebas as well as the single cell ones. Some of the latter build hard coverings (tests) for themselves. The other members of the unikonts are the fungus kingdom and the animal kingdom, which are sister kingdoms, having shared a common ancestor right before they branched off. There are other single cell organisms that are related to animals and fungi as well.
As you can see, the old protist kingdom had many different lineages of life shoe-horned into it, and the kingdoms that developed from its members were chopped off and boxed separately from it in the Five (or Six) Kingdoms scheme.
Why should you or your children learn about the supergroups of eukaryotes? It gives you a richer view of life and one that your children will see in their future studies. Will the names stay the same? Maybe, or maybe not, but these are the names in current college biology books, and it is worthwhile to learn about them and their members now.
Enjoy your explorations of the living world!
Priscilla
Moving past zoology and botany April 30 2019, 0 Comments
Normally, I write about elementary or secondary education in my blog. In this one, I’m addressing an issue that starts in early childhood, and it affects the way children view the living world in their later studies.
Traditionally, Montessori life science (biology) was divided into zoology and botany. The divide began when young children sorted pictures into animals vs. plants. This exercise fit well with the two kingdom approach to classifying the living world. I certainly hope that Montessori teachers no longer use two kingdoms. Biologists began moving away from two kingdoms in the mid-1800s, although it took a hundred years and major advances in biochemistry and microscopy to complete the break. We can give children a more useful overview of the living world than simply animals and plants.
It is time to quit thinking of life science as zoology or botany, or structuring our teaching albums (manuals) this way. When we offer only two categories for living things, children miss much of the living world. While young children are not ready for lots of details, they can sort pictures of living things into three categories, the third being “Other living things.” This tells them that there are organisms that are neither plants nor animals, and it keeps the door open for further learning. Mushrooms, lichens, and kelp are examples of macroscopic organisms that fit under the “Other” heading.
I started my work to bring current science concepts and content to teachers over 20 years ago. My first conference workshop was about the Five Kingdom classification. I spent nearly a decade helping teachers move from two kingdoms to five kingdoms. Then I had to switch gears again as expanding knowledge (via DNA and RNA) of the relationships between living things led to new concepts of classification, principally the Tree of Life and phylogenetics. My book, Kingdoms of Life Connected: A Teacher’s Guide to the Tree of Life, has learning activities and resources for exploring all the branches of life and viruses, too.
The microscopic living world is more abstract and harder to observe than plants and animals, but that does not mean that children shouldn’t know about it. They can learn that microorganisms help plants grow, recycle nutrients, and make foods like yogurt and cheese possible. The disease-causing microorganisms are the ones that we experience most directly, and these get the most attention, but children need to understand the vital importance of microorganisms to all ecosystems.
The book, Tiny Creatures, by Nicola Davies and Emily Sutton (2014) is a valuable resource for introducing young children to the microscopic world. These authors have a second book (2017), Many: The Diversity of Life on Earth, which supports a more inclusive view of life. The Invisible ABCs by Rodney P. Anderson (2006) sounds like it would be for early childhood, but it looks better for beginning elementary. This publication from the American Society for Microbiology has accurate information and good images of the organisms. Its breezy style makes this abstract world more interesting.
Moving past botany and zoology also means considering more than biological classification. It means thinking about the ecosystems, environments, and interactions of life, the structures of life, and the evolutionary history of organisms. Elementary children will have a better idea of the importance of microorganisms after they read Ocean Sunlight: How Tiny Plants Feed the Seas by Molly Bang and Penny Chisholm (2012). This book uses the term “plants” for the ocean’s protists that perform photosynthesis, even though many are not on the green algae-plant lineage. More importantly, it shows children the microbial underpinnings of the ocean ecosystem.
In elementary life science studies, there will be times to focus on the animals or the plants, but children will have a better perspective if they start with an introduction to the whole Tree of Life and learn to use this conceptual framework. As children develop their abstract thinking, they are likely to be interested in exploring all the branches of life. They will need good tools, such as magnifiers and microscopes, to help them observe the protists and prokaryotes. They also need appropriate search terms for finding resources they can read and understand.
I hope you and your children enjoy studying the greater living world.
Priscilla
The New Edition of Kingdoms of Life Connected is here! October 30 2016, 0 Comments
The second edition of my book, Kingdoms of Life Connected: A Teacher’s Guide to the Tree of Life, is available now. I wrote the first edition in 2008, and it was already time for an update this year. New information keeps coming in all fields of science. This leads to gradually evolving ideas, but change has been exceptionally rapid in the field of systematics, the study of the diversity of life.
The flood of DNA information continues, and we must bear that in mind in our presentations. It would be better to state that the story you tell is based on the evidence scientists have gathered for now. In the future, there could be adjustments. This doesn’t mean that all the information about the Tree of Life will change. Instead there will be small alterations. The potential for change certainly doesn’t excuse the presentation of obsolete classifications as anything other than history.
One of the hardest tasks for my book revision was finding up-to-date children’s books about the diversity of life. I had to leave many older, but valuable, books on the resource lists. At least it is easier to find out-of-print books now than it was a decade ago. I also found that publishers have reprinted some valuable older books. They include Peter Loewer’s Pond Water Zoo: An Introduction to Microscopic Life. Jean Jenkins illustrated this book in black and white, and it has attractive, clear drawings of many protists, bacteria, and microscopic animals, along with text that upper elementary children can read. You will have to warn your children that the classification scheme presented, the Five Kingdoms, is obsolete, but the information about the groups of organisms is still quite good.
A forty-year-old book by Alvin and Virginia Silverstein, Metamorphosis: Nature’s Magical Transformations, has been reprinted by Dover Books. It has a chapter on sea squirts that shows the tadpole-like larval stage and tells about the life cycle of these chordates. I haven’t found another children’s book that tells this story. The black and white illustrations show how old the book is, but there didn’t seem to be a good alternative.
I know the pain of having to purchase a new edition of a reference book. My favorite biology textbook cost nearly $200, and I see the new edition, just published this month, is priced at $244. Yikes, that’s hard on the budget. If you own the first edition of Kingdoms of Life Connected, you will be able to purchase the ebook version – the pdf file – of the book at a reduced price. Please email info (at) bigpicturescience (dot) biz for information about how to do this.
Three cheers (and three books) for bacteria! September 10 2016, 0 Comments
I’m always happy to find children’s books that portray bacteria as something other than germs. In my recent searches, I’ve found three gems. Two of them came from Australia, but I found the shipping was quick. The publisher is Free Scale Network, and the books are sold by Small Friends Books http://www.smallfriendsbooks.com/. The authors are Ailsa Wild, Aviva Reed, Briony Barr, and Dr. Gregory Crocetti.
It’s not often that bacteria get to be the protagonists, but in The Squid, the Vibrio, and the Moon the heroes are bacteria that help a young bobtail squid evade its predators. The story is set near the Hawaiian Islands, and it is dramatic and engaging. The attractive illustrations do a great job of supporting the story. They combine scales and will need some explanation, but the size scale at the front will help children keep all the components of the story in perspective.
The second book, Zobi and the Zoox, is set in a coral colony on the Great Barrier Reef. The protagonist is a rhizobia bacterium, Zobi for short. The action takes place in a coral polyp named Darian. The personification of these organisms could be distracting, but it isn’t. It helps one keep the characters separate and follow the action. There’s plenty of action as the coral faces warming in the ocean.
Both of these books can give children a greater appreciation for the many roles that bacteria play in making the biosphere work. It is easy to say that bacteria are an important part of all ecosystems, but that statement needs to be followed with great examples of actual symbioses like these books provide.
These two books are 38 pages long, and they can be enjoyed as a read-aloud by beginning elementary children. Older elementary can read the books themselves, and even secondary levels can learn from them. There is a glossary and several pages of additional information in the back of the books.
The third book that would be a great addition for studies of the microbial world is Inside Your Insides: A Guide to the Microbes That Call You Home by Claire Eamer, illustrated by Marie-Eve Tremblay. It was just released this month. This book has a wide range of information about microbes – what they are, where they live, and what they have to do with us and our world. The illustrations are goofy and cartoonish, but they work well enough to help children picture what is going on. The information is accurate and current, something that is hard to find in any children’s science book, much less one on microbes. Upper elementary children will likely enjoy the corny jokes sprinkled through the book, but they will also find plenty of good information. You could read it to lower elementary children.
Tweaking the Tree of Life - Again! August 19 2016, 0 Comments
If you look closely at my Tree of Life chart, you may notice changes. Knowledge about the early branches of the eukaryotes has grown, and it was time for another adjustment in the protists. This time I changed the label on the unikonts to also include a newer term for them, the Amorphea. Some biologists wanted this change because the original hypothesis about what makes the unikonts unique failed. The unikonts do not always have one flagellum, and they have two basal bodies (the part from which flagella grow), like other eukaryotes. What they do have is a unique fusion of three genes. This condition is so rare that it is unlikely to arise twice. The lineage of amoebas, animals, and fungi is still called the unikonts by many biologists, so I left that name on the chart.
The other main branch of eukaryotes, known informally as the bikonts, has a fusion of two different genes, another rare feature. The branch that includes chromalveolates (brown algae, diatoms, ciliates, etc.) and rhizarians (foraminiferans, radiolarians, etc.) has a much less wieldy name. It is now known as SAR (or Sar), an abbreviation for stramenopiles, alveolates, and rhizarians, and I added this to the chart. The evidence now points to some associations that I wanted to include on my Tree of Life. It appears that the Archaeplastida and SAR are more closely related to each other than they are to the Excavata (euglenas, Giardia, etc.). I’ve moved the branch positions on the chart to show this.
I like a newer term for the main branches of the eukaryotes. They are called the eukaryotic supergroups, which is a good descriptor for them.
You may be wondering what to do with your Tree of Life chart if you printed it from the older files. At lower elementary, I would do little more than adding the SAR and Amorphea labels. At that level, it is about showing a broad sweep of life, not the more exacting details. At upper elementary, you may wish to briefly explain about the changes since your chart was printed. Secondary students can learn more about these changes and modify their chart if they are interested.
And then there is that little fact we like to ignore. There are at least as many organisms not shown on our charts (even the more sophisticated scientific ones) as we show there. DNA studies show as many or more bacteria that have never been cultured or named as known bacteria. There are many named, but unplaced protists. Life isn’t simple! Is this the last version of the Tree of Life? Not likely, but it works for now.
You may also be wondering why I bothered to change the chart. Why not start new users of it with the most up-to-date information? As the flood of information continues, it will be best to go forward, not back. The most important thing is that children understand the Tree of Life and the evolutionary history it reflects. As a recent article in Nature Microbiology (2016, article number 16048) states “The tree of life is one of the most important organizing principles in biology.”
Tweaking the Tree of Life December 14 2014, 2 Comments
I’ve made a few changes to my Tree of Life and have new files available for free download. The changes are in the prokaryotes and protists. The three true kingdoms, the plants, animals, and fungi are still the same. These changes aren’t large, but they make the chart more accurate and useful.
Perhaps I should start by stating current rules on what constitutes a kingdom. Like any other lineage of life, a kingdom is an ancestor and all of its descendants. Organisms that are not descendants of that ancestor are excluded. That is why the Five Kingdom classification is no longer used. Two of those kingdoms, Monera and Protista, are not valid.
On my prokaryote chart, the only change is in the title. I’ve changed “Kingdom Monera” to “formerly Kingdom Monera” and reduced the font size. I wanted put stronger emphasis on the fact that Kingdom Monera is obsolete. It is no longer accepted by biologists because the two branches, bacteria and archaea, are tremendously different at the cell level. While they may have shared an ancestor very long ago, that ancestor would be the ancestor of all life, not just prokaryotic life.
On my protist chart, I changed both the title and the rhizaria branch. Biologists have good evidence that the rhizaria lineage, the stramenopile lineage, and the alveolate lineage shared a common ancestor more recently than the common ancestor of eukaryotes. The lineage is called SAR, an abbreviation for stramenopile, alveolate, and rhizaria. On the chart, I moved the base of the rhizaria lineage up onto the chromalveolate branch (which symbolizes the common ancestors of stramenopiles and aveolates) rather than showing the rhizaria as equally related to all the bikonts.
There are many uncertainties still in the protists, which are not a kingdom because they exclude the plants, animals and fungi. For convenience biologists group these eukaryotes into the informal group we call protists. There is an overwhelming amount of variety in this hodge-podge of life. When you introduce children to the protists, it is good to tell them that the branches on the chart are just the main branches, the ones with many known members. There are lots of other smaller branches as well. New protists are still being discovered and many that we have known of for years are yet to be studied enough to place them on the Tree of Life.
The Tree of Life gives a good framework for children to use as they address further diversity of life. It’s good to remind them that each of the main branches on the chart holds many other lineages, and life is always surprising us with its endless experiments. No chart will be valid for decades, at least not until we have studied many more organisms and determined configurations of many more lineages.
Happy explorations in life. You can use the comments to ask questions about these changes.
Priscilla