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Does anybody know what kind of tree is this?

Does anybody know what kind of tree is this?


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I saw this tree yesterday and I liked it. It is around 1.5 m. I did some search on internet and thought it might be Holly, but I'm not an expert on trees. So I wanted to ask you, does anyone know what kind of tree is this?

Location:The Netherlands


Looks like a holly, similar to English holly ( at least that is that it is called in the US ) .There are different cultivars . It has been pruned to a tree shape .


Overview of How Trees Grow and Develop

Steve Nix is a member of the Society of American Foresters and a former forest resources analyst for the state of Alabama.

Although a tree is common and familiar to all of us, how a tree grows, functions and its unique biology is not so familiar. The interrelationship of all a tree's parts is very complex and especially so is its photosynthetic properties. A tree begins life looking very much like every other plant you've seen. But give that seedling about a month and you will begin to see a true single stem, tree-like leaves or needles, bark, and the formation of wood. It takes only a few short weeks to see a plant showing its grand transformation into a tree.

Like everything else on earth, ancient trees sprung from the sea and are dependent on water. A tree's root system comprises the important water-collecting mechanism that makes life possible for trees and ultimately for everything on the planet that depends on trees.


  • NHGRI Education: http://www.genome.gov/Education/
  • Cold Spring Harbor DNA Learning Center: http://www.dnalc.org/
  • Evolution Lesson: http://www.indiana.edu/

Choosing a gene/protein to study

  • Popular science/media stories
  • Online Mendelian Inheritance in Man: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=OMIM
  • PubMed (searchable database of scientific journal articles) http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed

Finding the DNA/mRNA/protein sequence for that gene

  • NCBI/Genbank: https://www.ncbi.nlm.nih.gov/ Can access OMIM, BLAST, PubMed from here and search databases of protein and DNA sequences

Finding homologs in other species

Multiple sequence (DNA/RNA/protein) alignment tools

  • T-coffee: http://www.ebi.ac.uk/Tools/msa/tcoffee/ Has useful colored output (click "html" under Scores column of results page). Note that sequences must be in FASTA format (see help file).
  • ClustalW: http://www.ebi.ac.uk/Tools/msa/clustalw2/ Don't worry about all the optional parameters -- simply paste in all of your sequences in FASTA format.

General DNA/Protein analysis tools

Tutorial On Which This Idea Is Based


Does anybody know what kind of tree is this? - Biology

How are ABO alleles inherited by our children?

Problem set Each biological parent donates one of their two ABO alleles to their child. A mother who is blood type O can only pass an O allele to her son or daughter. A father who is blood type AB could pass either an A or a B allele to his son or daughter. This couple could have children of either blood type A (O from mother and A from father) or blood type B (O from mother and B from father).

Since there are 4 different maternal blood types and 4 different paternal blood types possible, there are 16 different combinations to consider when predicting the blood type of children.

The following Blood Type Calculator lets you determine the *possible* blood type of a child, given the blood types of the two biological parents or the *possible* blood types of one biological parent, given the blood types of the child and the other biological parent. We emphasize "possible" because, in most cases, blood typing is not conclusive when attempting to determine, include or exclude an individual as the parent of an offspring.

This calculator is based solely on theoretical principles. It would be a mistake to use this information to make any conclusions about your own family tree. Anyone wishing personal information about their own blood type inheritance is encouraged to contact their health care provider.


Flexibility in Determining Monophyletic Relationships


This figure depicts a cladogram of the order primates and examples of how to classify monophyletic, paraphyletic, and polyphyletic groups. According to this figure, new world monkeys, old world monkeys, apes, and humans belong in the same monophyletic group because we all share a most common recent ancestor. However, organisms can be classified differently, based on which common recent ancestor you choose to begin with.

1. A group is considered monophyletic if ___________.
A. All members of the group share a common recent ancestor, excluding the ancestor
B. All members of the group share a common recent ancestor, including the ancestor
C. Not all descendants of the common ancestor are included

2. Birds, reptiles, and turtles are all thought to share a common ancestor. Assuming this is true, these groups of animals, including their most common recent ancestor, would be considered what kind of taxonomic group?
A. Monophyletic
B. Paraphyletic
C. Polyphyletic

3. Branching orders in a monophylogenetic group shows us what?
A. Amount of evolution
B. Relationships between organisms
C. Future direction of evolution


How the Tree Frog Has Redefined Our View of Biology

Karen Warkentin, wearing tall olive-green rubber boots, stands on the bank of a concrete-lined pond at the edge of the Panamanian rainforest. She pulls on a broad green leaf still attached to a branch and points out a shiny clutch of jellylike eggs. “These guys are hatchable,” she says.

From This Story

A parrot snake homes in on red-eyed tree frog eggs, which can respond to its approach. (Christian Ziegler) A beloved symbol of biodiversity, the red-eyed tree frog, shown here in Panama, has evolved a flexible strategy for survival. (Christian Ziegler) Frog eggs one day after being laid. (Christian Ziegler) Eggs four days after being laid. (Christian Ziegler) Eggs clinging to a leaf over water hatch. (Christian Ziegler) Free-swimming tadpoles. (Christian Ziegler) Karen Warkentin says that frog embryos' behavioral decisions may be more sophisticated than we imagined. (Richard Schultz (3)) Why the bulging red eyes? To surprise predators so the frog can jump away—scientists call it "startle coloration." (Christian Ziegler)

Photo Gallery

Red-eyed tree frogs, Agalychnis callidryas, lay their eggs on foliage at the edge of ponds when the tadpoles hatch, they fall into the water. Normally, an egg hatches six to seven days after it is laid. The ones that Warkentin is pointing to, judging from their size and shape, are about five days old, she says. Tiny bodies show through the clear gel-filled membrane. Under a microscope, the red hearts would just be visible.

She reaches down to wet her hand in the pond water. “They don’t really want to hatch,” she says, “but they can.” She pulls the leaf out over the water and gently runs a finger over the eggs.

Sproing! A tiny tadpole breaks out. It lands partway down the leaf, twitches and falls into the water. Another and another of its siblings follow. “It’s not something I get tired of watching,” Warkentin says.

With just a flick of her finger, Warkentin has demonstrated a phenomenon that is transforming biology. After decades of thinking of genes as a “blueprint”—the coded DNA strands dictate to our cells exactly what to do and when to do it—biologists are coming to terms with a confounding reality. Life, even an entity as seemingly simple as a frog egg, is flexible. It has options. At five days or so, red-eyed tree frog eggs, developing right on schedule, can suddenly take a different path if they detect vibrations from an attacking snake: They hatch early and try their luck in the pond below.

The egg’s surprising responsiveness epitomizes a revolutionary concept in biology called phenotypic plasticity, which is the flexibility an organism shows in translating its genes into physical features and actions. The phenotype is pretty much everything about an organism other than its genes (which scientists call the genotype). The concept of phenotypic plasticity serves as an antidote to simplistic cause-and-effect thinking about genes it tries to explain how a gene or set of genes can give rise to multiple outcomes, depending partly on what the organism encounters in its environment. The study of evolution has so long centered on genes themselves that, Warkentin says, scientists have assumed that “individuals are different because they’re genetically different. But a lot of the variation out there comes from environmental effects.”

When a houseplant makes paler leaves in the sun and a water flea grows spines to protect against hungry fish, they’re showing phenotypic plasticity. Depending on the environment—whether there are snakes, hurricanes or food shortages to deal with—organisms can bring out different phenotypes. Nature or nurture? Well, both.

The realization has big implications for how scientists think about evolution. Phenotypic plasticity offers a solution to the crucial puzzle of how organisms adapt to environmental challenges, intentionally or not. And there is no more astonishing example of inborn flexibility than these frog eggs—blind masses of goo genetically programmed to develop and hatch like clockwork. Or so it seemed.

Red-eyed tree frog hatchlings were dodging hungry snakes a long time before Warkentin started studying the phenomenon 20 years ago. “People had not thought of eggs as having the possibility to show this kind of plasticity,” says Mike Ryan, her PhD adviser at the University of Texas in Austin. “It was very clear, as she was doing her PhD thesis, that this was a very, very rich field that she had sort of invented on her own.”

Karen Martin, a biologist at Pepperdine University, also studies hatching plasticity. “Hatching in response to some kind of threat has been a very important insight,” Martin says. “I think she was the first one to have a really good example of that.” She praises Warkentin’s sustained effort to learn big biology lessons from frog eggs: “I think a lot of people might have looked at this system and said, ‘Here’s a kind of a quirky thing that I could get some papers out of, and now I’ll move on and look at some other animal.’ She dedicated herself to understanding this system.”

Warkentin’s research “causes us to think more carefully about how organisms respond to challenges even very early in life,” says Eldredge Bermingham, an evolutionary biologist and director of the Smithsonian Tropical Research Institute (STRI, pronounced “str-eye”) in Gamboa, Panama. Warkentin, a biology professor at Boston University, conducts her field studies at STRI. That’s where she showed me how she coaxes the eggs to hatch.

The tadpoles leaping from the wet leaf still have a little yolk on their bellies they probably won’t need to eat for another day and a half. Warkentin keeps rubbing until only a few remain, stubbornly hiding inside their eggs. “Go on,” she tells them. “I don’t want to leave you here all by yourselves.”

The last of the tadpoles land in the water. Predatory bugs known as backswimmers wait at the surface, but Warkentin says she saved the tadpoles from a worse fate. Their mother had missed the mark, laying them on a leaf that didn’t reach over the pond. “If they were hatching on the ground,” she says, “then they would just be ant food.”

Warkentin was born in Ontario, and her family moved to Kenya when she was 6. Her father worked with the Canadian International Development Agency to train teachers in the newly independent country. That’s when she got interested in tropical biology, playing with chameleons, and watching giraffes, zebras and gazelles on the drive to school in Nairobi. Her family returned to Canada several years later, but at 20 she went hitchhiking and backpacking across Africa. “That was something that seemed perfectly reasonable in my family,” she says.

Before she started her PhD, she went to Costa Rica to learn more about the tropics and look for a research topic. The red-eyed tree frog’s terrestrial eggs caught her interest. She visited the same pond over and over again, and watched.

“I had the experience—which I’m sure other tropical herpetologists have had before and maybe didn’t think about—if you have a late-stage clutch, if you bump into them, they’ll hatch on you,” Warkentin says. “I bumped into a clutch, and they all were bailing out.”

She had also seen snakes at the pond. “What I thought was, wow, I wonder what would happen if a snake bumped into them,” she says, and laughs. “Like, with its mouth?” Indeed, she found that if a snake appears and starts attacking the clutch, the eggs hatch early. The embryos inside the eggs can even tell the difference between a snake and other vibrations on the leaf. “This is the thing, of going out in the field and watching the animals,” she says. “They’ll tell you things you didn’t expect sometimes.”

Biologists used to think this kind of flexibility got in the way of studying evolution, says Anurag Agrawal, an evolutionary ecologist at Cornell University. No longer. It’s exciting that Warkentin has documented wonderful new things about a charismatic frog, but Agrawal says there’s a great deal more to it. “I think that she gets credit for taking it beyond the ‘gee whiz’ and asking some of the conceptual questions in ecology and evolution.”

What are the advantages of one survival tactic over another? Even a 5-day-old frog has to balance the benefit of avoiding a hungry snake against the cost of hatching early. And, in fact, Warkentin and her colleagues have documented that early-hatching tadpoles were less likely than their late-hatching brethren to survive to adulthood, particularly in the presence of hungry dragonfly nymphs.

Plasticity not only lets frogs cope with challenges in the moment it might even buy time for evolution to happen. Warkentin has found that tadpoles also hatch early if they’re at risk of drying out. If the rainforest gradually became drier, such early hatching might become standard after countless generations, and the frog might lose its plasticity and evolve into a new, fast-hatching species.

One of the mainstays of evolutionary thinking is that random genetic mutations in an organism’s DNA are the key to adapting to a challenge: By chance, the sequence of a gene changes, a new trait emerges, the organism passes on its altered DNA to the next generation and gives rise eventually to a different species. Accordingly, tens of millions of years ago, some land mammal acquired mutations that let it adapt to life in the ocean—and its descendants are the whales we know and love. But plasticity offers another possibility: The gene itself doesn’t have to mutate in order for a new trait to surface. Instead, something in the environment could nudge the organism to make a change by drawing on the variation that is already in its genes.

To be sure, the theory that plasticity could actually give rise to new traits is controversial. Its main proponent is Mary Jane West-Eberhard, a pioneering theoretical biologist in Costa Rica affiliated with STRI and author of the influential 2003 book Developmental Plasticity and Evolution. “The 20th century has been called the century of the gene,” West-Eberhard says. “The 21st century promises to be the century of the environment.” She says mutation-centric thinking is “an evolutionary theory in denial.” Darwin, who didn’t even know genes existed, had it right, she says: He left open the possibility that new traits could arise because of environmental influence.

West-Eberhard says Warkentin’s group has “demonstrated a surprising ability of tiny embryos to make adaptive decisions based on exquisite sensitivity to their environments.” That kind of variation, West-Eberhard says, “can lead to evolutionary diversification between populations.”

Although not everyone agrees with West-Eberhard’s theory of how plasticity could bring about novelty, many scientists do now think that phenotypic plasticity will emerge when organisms live in environments that vary. Plasticity may give plants and animals time to adjust when they’re dumped in a completely new environment, such as when seeds are blown to an island. A seed that isn’t as picky about its temperature and light requirements might do better in a new place—and might not have to wait for an adaptive mutation to come along.

Also, many scientists think that plasticity may help organisms try out new phenotypes without being entirely committed to them. Early hatching, for example. Different species of frogs vary greatly in how developed they are when they hatch. Some have a stumpy tail and can barely swim others are fully formed, four-limbed animals. “How do you get that kind of evolved variation?” Warkentin asks. “Does plasticity in hatching time play a part in that? We don’t know, but it’s quite possible.”

The town of Gamboa was built between 1934 and 1943 by the Panama Canal Company, a U.S. government corporation that controlled the canal until 1979, when it was handed over to Panama. Gamboa, on the edge of a rainforest, is part ghost town, part bedroom community for Panama City and part scientific summer camp. Quite a few residents are scientists and staff at STRI.

When I visited, Warkentin’s team had up to a dozen people, including several undergraduates she refers to as “the kids.” One morning a posse of vigorous-looking young people in knee-high rubber boots, backpacks and hats departs Warkentin’s lab and strides across the field behind the school, past the tennis courts.

James Vonesh, a professor at Virginia Commonwealth University, who did a postdoctoral fellowship with Warkentin and still collaborates with her, points out his favorite sign in town, a holdover from the Canal Zone era: “No Necking.” It’s painted on the front of the stands at the old swimming pool, now part of the local firefighters’ sports club. Then he explains to one of the kids what “necking” means.

They walk down a road into a nursery for native plants, cross a ditch on a footbridge and arrive at Experimental Pond. It was built of concrete to specifications provided by Warkentin and Stan Rand, a revered frog researcher at STRI, who died in 2005.

On the pond’s far side is the group’s research area, bounded by a ditch on one side and a stream, then rainforest, on the other. There’s a metal-roofed shed with open sides, surrounded by dozens of 100-gallon cattle tanks used in experiments. They look like buckets set out to catch an array of extremely large leaks. Vonesh talks about the plumbing system with more enthusiasm than seems possible. “We can fill a cattle tank in three or four minutes!” he exclaims.

All that fast filling means the researchers can do quick experiments other aquatic ecologists can only dream of. Today they’re dismantling an experiment on predation. Four days ago, 47 tadpoles were put in each of 25 tanks along with one Belostomatid, a kind of water bug that eats tadpoles. Today, they’ll count the tadpoles to find out how many the Belostomatids ate.

A giant blue morpho butterfly flits by, its iridescent wings a shocking splash of electric blue against the lush green forest. “They come by, like, the same place at the same time of day,” Warkentin says.

“I swear I see that one every morning,” Vonesh says.

“It’s the 9:15 morpho,” Warkentin says.

Warkentin explains the experiment they’re finishing today. “We know that predators kill prey, obviously, and they also scare prey,” she says. When new-hatched tadpoles fall into a pond, water bugs are one of the threats they face. The tadpoles’ plasticity might help them avoid being eaten—if they can detect the bugs and somehow respond.

Ecologists have developed mathematical equations describing how much prey a predator should be able to eat, and elegant graphs show how populations rise and fall as one eats the other. But what really happens in nature? Does size matter? How many 1-day-old tadpoles does a fully grown water bug eat? How many older, fatter tadpoles? “Obviously, we think small things are easier to catch and eat and stick in your mouth,” Vonesh says. “But we really haven’t incorporated that into even these sort of basic models.”

To figure out how many tadpoles got eaten, the undergraduates, graduate students, professors and a postdoctoral fellow have to get every last tadpole out of each tank to be counted. Vonesh picks up a clear plastic drink cup from the ground by his feet. Inside is a water bug that was feasting on tadpoles. “He’s a big guy,” he says. He reaches into a tank with the net, pulling out tadpoles one or two at a time and putting them in a shallow plastic tub.

“You ready?” asks Randall Jimenez, a graduate student at National University of Costa Rica.

“I’m ready,” Vonesh says. Vonesh tips the tank as Jimenez holds a net under the gushing water. The guys watch the net for any tadpoles that Vonesh missed. “See anybody?” Vonesh asks. “Nope,” Jimenez says. It takes almost 30 seconds for the water to flow out. Most of the researchers wear tall rubber boots to protect against snakes, but they’re useful as the ground rapidly turns to mud.

A flock of grackles wanders nonchalantly through the grass. “They like to eat tadpoles,” Vonesh says. “They like to hang out and pretend they’re looking for earthworms, but as soon as you turn your back, they’re in your tub.”

Vonesh takes his tub of tadpoles to the shed where Warkentin photographs it. A student will count the tadpoles in each picture. Insects and birds sing from the trees. Something falls—plink—on the metal roof. A freight train whistles from the train tracks that run alongside the canal a group of howler monkeys barks a raucous response from the trees.

To scientists like Warkentin, Gamboa offers a bit of rainforest about an hour’s drive from an international airport. “Oh, my god. It is so easy,” she says. “There’s a danger of not appreciating how amazing it is. It’s an incredible place to work.”

During the day, the iconic red-eyed frogs aren’t hopping about. If you know what you’re looking for, you can find the occasional adult male clinging to a leaf like a pale green pillbox—legs folded, elbows tucked by his side to minimize water loss. A membrane patterned like a mosque’s carved wooden window screen covers each eye.

The real action is at night, so one evening Warkentin, Vonesh and some guests visit the pond to look for frogs. The birds, insects and monkeys are quiet, but amphibian chirps and creaks fill the air. One frog’s call is a clear, loud “knock-knock!” Another sounds exactly like a ray gun in a video game. The forest feels more wild at night.

Near a shed, a male red-eyed tree frog clings to the stalk of a broad leaf. Tiny orange toes outspread, he shows his white belly and wide red eyes in the light of multiple headlamps. “They have these photogenic postures,” Warkentin says. “And they just sit there and let you take a picture. They don’t run away. Some frogs are, like, so nervous.” Maybe that’s why the red-eyed tree frog has gotten famous, with its picture on so many calendars, I suggest—they’re easier to photograph than other frogs. She corrects me: “They’re cuter.”

Scientists think the ancestors of modern frogs all laid their eggs in water. Maybe the red-eyed tree frog itself could have evolved its leaf-laying habits as a result of phenotypic plasticity. Maybe an ancestor dabbled in laying its eggs out of the water, only on really wet days, to get away from aquatic predators—a plastic way of dealing with a dangerous environment—and that trait got passed on to its descendants, which eventually lost the ability to lay eggs in water at all.

Nobody knows if that’s how it happened. “That was a very long time ago and no longer amenable to those kinds of experiments,” Warkentin says.

But intriguing experiments on another kind of frog—one that might be still navigating the transition between water and land—are underway. Justin Touchon, a former PhD student of Warkentin’s, studies how the hourglass tree frog, Dendropsophus ebraccatus, lays its eggs, which are less packed with jelly and more prone to drying out than red-eyed tree frogs’. A female hourglass tree frog seems to choose where to lay eggs based on dampness. At ponds shaded by trees, Touchon found, they’ll lay eggs on leaves above the water, but at hotter, more exposed ponds, the eggs go in the water.

In a study published last month, he found that eggs were more likely to survive on land if there was a lot of rain, and more likely to survive in water if rainfall was scarce. He also looked at rain records for Gamboa in the past 39 years and found that while overall rainfall hasn’t changed, the pattern has: Storms are larger but more sporadic. That change in the environment could be driving a change in how the hourglass tree frogs reproduce. “It gives a window on what caused the movement to reproducing on land to occur,” Touchon says—a climate that shifted to have lots of steady rain could have made it safer for frogs to lay eggs out of the water.

Warkentin’s group is based on the ground floor of the Gamboa Elementary School, which closed in the 1980s. One morning, Warkentin sits on an ancient swivel chair with dusty arms at a retired office desk, doing what looks like a grade-school craft project.

On the floor at her left sits a white bucket with rows of green rectangles duct-taped to the inside. She reaches down and pulls one out. It’s a piece of leaf, cut with scissors from one of the broad-leafed plants by the experimental pond, and on it is a clutch of gelatinous red-eyed tree frog eggs. She tears off a strip of tape and sticks the piece of leaf onto a blue plastic rectangle, cut from a plastic picnic plate.

“You can do an amazing amount of science with disposable dishware, duct tape and galvanized wire,” she says.

She stands the card in a clear plastic cup with a bit of water in the bottom, where the tadpoles will fall when they hatch, and goes on to the next piece of leaf. The tadpoles will be part of new predation experiments.

There’s great explanatory value in simple models—but she wants to understand how nature actually operates. “We’re trying to grapple with what’s real,” she says. “And reality is more complicated.”


Filling in details and posing new questions

Tool-making was one feature that made human ancestors very different from those of apes, but it was not the only feature. Getting a handle on other features would require more bones, but most of the Australopithecine finds through the mid 20th century were parts of skulls or sometimes also very small pieces from other body parts. In a concerted effort to find more hominid bones, teams of scientists began exploring the Afar Triangle region of Ethiopia, near the Hadar village, where the geology and climate had been ideal for preserving and burying skeletons. Camps were set up in the early 1970s and prominent scientists were invited to visit. These included Mary Leakey and a rising star in the paleoanthropology community, Donald Johanson of the Cleveland Museum.

Johanson and other team members in 1974 unearthed what is now the most famous hominid skeleton. Although incomplete, virtually everything that is missing on one side of the body is present on the opposite side. The bones of this skeleton matched previously discovered specimens of the species: Australopithecus afarensis, but they also showed something new. Examining the knee joint, Johanson and his colleagues saw that it could lock the leg into a straight position, just like the legs of H. erectus and modern humans. Furthermore, the location of the foramen magnum, the hole at the base of the skull, was well defined in this specimen. These two features meant that A. afarensis had walked upright, rather than skimming along on its knuckles like an ape. But just like A. africanus, the brain volume of A. afarensis was only chimpanzee-size. Furthermore, this species was more than a million years older than H. erectus. (Figure 6 shows the three species' skulls.)

Figure 6: Three models of skulls - A. africanus (left), A. boisei (center), H. erectus (right). image © David Ludwig

Johanson’s team named the specimen Lucy, because they were listening to the Beatles song Lucy in the Sky with Diamonds while examining their find. Because its jaw was less massive compared with other Australopithecines, A. afarensis is thought to be either a direct ancestor of the human line or at least closely related to such an ancestor. In contrast, A. africanus, A. boisei, and A. robustus are now recognized as offshoot branches of the line that leads to Homo. This fits with the Leakey finding of A. africanus co-existing with H. habilis. They were cousins whose progeny were destined for very different fates.

What made Lucy different from other hominid specimens?


Phylogenetic Tree

A phylogenetic tree, or cladogram, is a schematic diagram used as a visual illustration of proposed evolutionary relationships among taxa. Phylogenetic trees are diagrammed based on assumptions of cladistics, or phylogenetic systematics. Cladistics is a classification system that categorizes organisms based on shared traits, or synapomorphies, as determined by genetic, anatomical, and molecular analysis. The main assumptions of cladistics are:

  1. All organisms descend from a common ancestor.
  2. New organisms develop when existing populations split into two groups.
  3. Over time, lineages experience changes in characteristics.

Phylogenetic tree structure is determined by shared traits among different organisms. Its tree-like branching represents diverging taxa from a common ancestor. Terms that are important to understand when interpreting a phylogenetic tree diagram include:

  • Nodes: These are points on a phylogenetic tree where branching occurs. A node represents the end of the ancestral taxon and the point where a new species splits from its predecessor.
  • Branches: These are the lines on a phylogenetic tree that represent ancestral and/or descendant lineages. Branches arising from nodes represent descendant species that split from a common ancestor.
  • Monophyletic Group (Clade): This group is a single branch on a phylogenetic tree that represents a group of organisms that are descended from a most recent common ancestor.
  • Taxon (pl.Taxa): Taxa are specific groupings or categories of living organisms. The tips of branches in a phylogenetic tree end in a taxon.

Taxa that share a more recent common ancestor are more closely related than taxa with a less recent common ancestor. For example, in the image above, horses are more closely related to donkeys than to pigs. This is because horses and donkeys share a more recent common ancestor. Additionally, it can be determined that horses and donkeys are more closely related because they belong to a monophyletic group that does not include pigs.


Return of Periodical Cicadas in 2021: Biology, Plant Injury and Management

Photo 1: This will be a common scene in 2021, when hundreds of thousands of cicadas will emerge beneath trees in more than a dozen eastern states. Unless otherwise noted, all photos courtesy of the author.

Natural events often occur in predictable cycles. In temperate North America, we are accustomed to the annual production of the leaves, flowers and seeds of our deciduous oaks and maples. Agave americana, the giant agave native to Mexico and Texas, is commonly known as the century plant due to its enormous periodic bloom of a decade or two. Even celestial events occur with clockwork predictability, like the visit of Halley’s comet every 75 years. If you live in the eastern United States, get ready.

In the spring of 2021, trillions of periodical cicadas are expected to emerge in parts of the following states: Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia. They will be a source of wonder and consternation as they emerge from the earth and lay eggs in treetops. (Photo 1)

What are periodical cicadas?

Taxonomically, periodical cicadas are members of a large clan of insects known as Hemiptera, with piercing-sucking mouthparts and gradual metamorphosis, meaning juveniles are called nymphs rather than larvae. During development, there is no pupal stage. Other familiar members of this clan and close relatives of cicadas include leafhoppers, spittle bugs and lanternflies. Periodical cicadas differ from their relatives, annual and dog-day cicadas, which appear yearly in summer and autumn throughout North America and much of the world.

By virtue of their visits in cycles of 13 or 17 years in distinct locations, periodical cicadas are unique in the animal realm. These regional, periodic visits are called broods, and there are three broods of 13-year cicadas and 12 broods of 17-year cicadas. Scientists classify the different broods using Roman numerals. Periodical cicadas emerging in 2021 are known as Brood X, with the X, of course, adding an element of consternation that will be pondered by many and exploited by the media. A common misconception regarding periodical cicadas is that they are but a single species. They are not. There are four species of 13-year cicadas, which go by the names of Magicicada neotredecim, M. tredecim, M. tredecassini and M. tredecula, and three species of 17-year cicadas, called M. septendecim, M. cassini and M. septendecula.

While Native Americans were fully aware of periodical cicadas by the time the first colonists landed on the New World’s shores, colonial Europeans had never experienced a massive appearance of large, boisterous insects emerging from the earth and flying to treetops. In 1633, William Bradford, the first governor of Massachusetts, wrote, “All the month of May, there was such a quantity of a great sort of flyes like for bigness to wasps or bumblebees, which came out of holes in the ground … and ate green things, and made such a constant yelling noise as made all the woods ring of them, and ready to deaf the hearers.”

For immigrants escaping persecution in parts of Europe, this vast, disturbing natural event awakened long-forgotten fears of the eighth biblical plague, the plague of locusts. Throughout the colonies, the name locust soon became attached to periodical cicadas. Of course, we know locusts are grasshoppers, chewing insects of the Orthoptera clan that sometimes appear in astounding numbers, consuming everything plantlike in their path. However, journalists and a misinformed public continue to refer to periodical cicadas as locusts.

Seventeen years underground, and then what?

As you read this article, there are literally trillions of cicadas in subterranean galleries a foot or more beneath the soil’s surface. Densities of periodical cicadas can be staggering, with some areas harboring as many 1.4 million nymphs per acre (3.5 million per hectare). (Photo 2) Brood X nymphs entered the soil in the summer of 2004 after hatching from eggs deposited by their mothers in small branches in the treetops. After burrowing into the soil, they feed on small roots of several different species of deciduous trees, but they also may feed on rootlets of gymnosperms and herbaceous plants, including grasses. Nymphs and adults pierce xylem elements with their sucking mouthparts and consume xylem fluid. Hatchling cicadas, known as first-instar nymphs, shed their exoskeletons four times, developing into fifth-instar nymphs by their 17th year, when they emerge from the soil.

Photo 2 In some areas, cicadas will reach densities even greater than those in the once square foot depicted here, translating to more than a million per acre.

Environmental cues linked to development and the exact timing of emergence are not fully understood, but the nutritional quality of plants consumed, soil temperatures and day length are all believed to play a role. When soil temperatures reach about 64 F, the massive synchronous emergence of cicada nymphs from their galleries will begin and last for only a matter of days. In the spring of 2020, at locations in Maryland, Virginia, the District of Columbia, Kentucky and Ohio, early-rising periodical cicadas of Brood X emerged between April 19 and June 14 (Raupp et al. 2020). Synchrony is critical for periodical cicadas. Their bizarre strategy for survival is to simply overwhelm hungry predators by filling all of their bellies and leaving yet enough cicadas to survive and perpetuate their species. This strange survival scheme is called predator satiation. It has proven successful for hundreds of thousands of years.

The bulk of cicadas emerge at dusk and move from the soil to vertical structures including trees, underlying vegetation and human-made structures such as buildings and lawn furniture. After shedding their last nymphal skin, adults expand their wings before their exoskeleton hardens. In the first 24 hours, the toll on emerging cicadas will be vast, but those that survive move to the treetops to mature. After several days, with wings and acoustic organs functional, males fly, aggregate in clusters of trees and begin an ear-splitting chorus designed to attract other members of their species. Membranes on both sides of their abdomen, called tymbal organs, vibrate to produce a variety of calls that can approach 100 decibels, an intensity slightly lower than that of a leaf blower or chain saw.

Once members of the same species are assembled, males use courtship calls to woo potential mates. If a female likes the male’s performance, she signifies her willingness to mate with an audible flick of her wings. Inseminated females eventually move to small branches on favored trees to lay eggs. Using a rigid appendage on the abdomen called an ovipositor, the cicada cuts slivers into twigs and deposits batches of 20 to 30 eggs into each of these egg nests. (Photo 3) Individual females may lay up to 600 eggs during the course of a lifetime. In the relative safety of the egg nest, eggs develop for six to 10 weeks, after which time tiny cicada nymphs drop from the canopy to the ground.

Photo 3 Trees are injured when females slice branches and deposit eggs into the wood with an egg-laying appendage called an ovipositor.

Within a few minutes, they burrow into the soil, where they locate roots of plants and begin feeding for the next 17 years.

What injury do cicadas cause?

Photo 4 Small branches may have dozens of egg nests, causing them to flag and often break. Photo by Paula Shrewsbury.

Injury caused by xylem-feeding of adult cicadas is inconsequential. The real insult to woody plants comes from wounds caused when cicadas slice branches to insert eggs. This injury causes the tips of many branches to wither and die just distal to the sites of egg laying. These dead terminals droop, and the injury is called flagging. Eventually, dead terminals may break entirely and drop, littering the ground below with branches. Branches that do not break and drop may eventually enclose the ovipositional wound, but the wound site may be structurally deficient and may break at a later time. Concern also exists that egg-laying wounds may be entry points for pathogens to colonize plants. (Photos 4 & 5)

Photo 5 Recently transplanted trees, like this young oak, may be severely injured by cicadas and may not survive.

With respect to the types of plants used for oviposition, the bad news is that periodical cicadas are broad generalists. An important study conducted by Miller and Crowley (1998) at the Morton Arboretum of 140 genera of woody plants revealed that more than half sustained injury caused by ovipositing females of Brood VIII. Some of the most heavily attacked, and those experiencing the greatest twig breakage, included Acer, Amelanchier, Carpinus, Castanea, Cercidphyllum, Cercis, Chionanthus, Fagus Quercus, Myrica, Ostrya, Prunus, Quercus and Weigela. Several genera sustained no injury despite being surrounded by trees that were attacked. They included Rhus, Asimina, Berberis, Gymnocladis, Viburnum, Euonymus, Maclura, Abies, Larix, Picea, Pinus, Pseudotsuga and Phellodendron.

A more recent account of 42 common woody-plant species added several new genera to the list, and found that all but 10 were used as ovipositional hosts for Brood X cicadas in Delaware. This study found that native and non-native woody plants were equally likely to be used for oviposition by cicadas, but alien plants, those with no other known congener in the United States, were less likely to be used for oviposition (Brown and Zuefle 2009). (Photo 6)

Photo 6 On established trees, many branches will flag and break off where cicadas are abundant.

Several other factors besides taxonomic identity of a plant affect the use of a plant as an egg-laying host for cicadas. Small, bushy plants tend to receive fewer egg nests than those having simpler structure with longer branches. Several studies revealed trees near forest edges and branches with sunny exposures sustain more cicada injury. This places nursery stock, orchards and recently transplanted saplings in commercial and residential landscapes at elevated risk, particularly if there are established trees nearby with a history of supporting cicadas.

While flagging and limb breakage occur in the short term, there is little evidence that cicadas pose a long-term threat to the vitality of trees, especially older established ones (Miller and Croft 1998). A study of early successional trees found no clear effect of cicada ovipostion on growth rates or radial growth of trees attacked by cicadas (Clay et al. 2009).

Are there natural agents limiting cicada populations?

As mentioned previously, periodical cicadas evolved the strange predator-
satiation strategy as a means of survival in the face of intense pressure from so many creatures anxious to eat them. Starlings, grackles, robins, blue jays, blackbirds, sparrows, titmice, vireos, gulls, terns and several other feathered reptiles eat cicadas. Snakes, turtles and fish consume them. Skunks, squirrels, mice and other small mammals eat cicada adults and nymphs. Many predatory arthropods, including spiders, centipedes, opilionids, ants, stink bugs, assassin bugs and flies, have been observed feeding on various life stages of cicadas. A specialized fungus, Massospora cicadina, infects and kills large numbers of cicadas in each brood and, in a fascinating twist, becomes a sexually transmitted disease in cicada populations.

Cats and dogs will consume large numbers of cicadas in 2021. Cicadas in general, and periodical cicadas specifically, were and are important sources of protein for indigenous people, including Native Americans.

In addition to death due to biotic agents such as predators and disease, abiotic factors, including extreme weather conditions such as thunderstorms, doom many. Human activity such as deforestation, agriculture and urbanization with attendant proliferation of impervious surfaces is responsible for local extirpation of cicada populations. In recorded history, two broods of cicadas have disappeared, Broods XI and XXI.

Preventing cicada injury to trees

While a typical knee-jerk reaction might be to treat trees with insecticides, several scientific studies show this may not be the best way to go. Protecting trees from cicada injury is of the utmost importance to fruit growers, where injury to highly susceptible trees such as apples, peaches and cherries directly impacts yields and profits. Important data collected in a commercial orchard clearly demonstrated the efficacy of using netting rather than insecticides to protect trees from egg-laying cicadas. Trees netted with 1.0-cm mesh sustained virtually no damage, whereas trees treated several times with potent carbamate and synthetic pyrethroid insecticides received eight to 25 times more injury from cicadas. (Chart 1)

Chart 1 A comparison of different control tactics clearly shows that trees protected with 1.0-cm mesh netting received far less cicada injury, measured as number of egg scars, than trees treated with insecticides or enclosed in netting with larger mesh sizes. Data plotted from Hogmire et al. (1990).

Mesh size does matter. While 1.0-cm mesh performed well, when mesh size increased to 2.5 cm, cicada damage was as severe as that of untreated trees (Hogmire et al. 1990). Another important finding of this study was that netting proved to be only slightly more expensive than insecticide applications. A second trial with active ingredients listed by the Organic Materials Review Institute (OMRI) for use in the production of organic crops found six applications of emulsions of kaolin clay, neem and karanja oils to be ineffective in reducing the number of egg nests, while fabric netting provided complete protection from cicadas (Frank 2020). Cicadas actively move about and lay eggs for a period of several weeks, necessitating repeated applications of contact insecticides as new cicadas arrive.

Do soil injections of neonicotinoids provide longer-lasting protection to small trees compared to exclusionary nets? Our research demonstrated that soil drenches of imidacloprid applied to sapling Tilia were only about half as effective at preventing egg laying compared to 1.0-cm mesh nets (Ahern 2005). The material cost to enclose a 3-meter- (10-foot-) tall tree was $2.82 in 2005. Time to enclose a sapling was a matter of minutes. (Photo 7)

Photo 7 Small trees can be protected from cicada injury by enclosing them in netting.

Netting clearly provides superior protection and may be cost effective for small trees, but what about mature trees? Aforementioned studies indicate that the effects of cicada injury, while dramatic, likely have minimal negative effects on the long-term growth of trees. However, in addition to improving the short-term appearance of injured trees, careful sanitary pruning of damaged branches may enhance wound closure and reduce structural defects in branches as they mature.

How should we prepare for the impending arrival of Brood X?

For arborists, now is an excellent time to plan and discuss the upcoming appearance of Brood X with clients. Step one involves determining if cicadas will be present on your clients’ properties. Even though Brood X will appear in more than a dozen states, their distribution will be patchy, meaning in some areas vast numbers will emerge, but miles away few or none will be seen. If you are familiar with the cicada history of your clients, you may already know that cicadas emerged at their properties in 2004. If your business is new to an area or if you have expanded your client base to new locations, talk to your clients and see if they have knowledge of what happened in their landscape 17 years ago.

If cicadas are likely, inventory properties proactively to evaluate which trees are at greatest risk and discuss plans for protecting those trees. Several commercial vendors sell plastic netting suitable for protecting trees, but remember, mesh sizes larger than 1.0 cm may not prevent ovipositional injury. Suppliers can be found on the internet, and netting can be purchased in bulk. Some naturalists have expressed concerns about nesting birds becoming trapped in netted trees, so inspect trees prior to netting to avoid harming wildlife.

Urban foresters and planners should consider delaying planting woody plants in the spring of 2021 in areas known to support populations of periodical cicadas. If trees were planted in the fall of 2020 or in recent years past, consider protecting them.

Final thought

Excellent information on all things related to cicadas can be found at the Cicada Mania website https://www.cicadamania.com/.

Get ready. Just as cherry trees bloom each spring and Halley’s comet stops by every 75 years, Brood X cicadas will return in 2021.


Plants

Plants are essential to all life on Earth. They are special because they are able to make their own food by a process called photosynthesis where they take carbon dioxide from the atmosphere and turn it into sugar. The sugars can then be used for energy for growth and many more functions but the plant material provides the basis of almost all food chains.

Plants include a range of different groups that can all photosynthesize but can be very different physically and genetically. Included in the plant kingdom are the flowering plants or angiosperms, the gymnosperms – woody plants without flowers but with seed and cones, the ferns, lycophytes – similar to ferns but only have a single vein through each leaf, the bryophytes (mosses, hornworts and liverworts), and some algae.

All plants that grow flowers and fruit belong to the group known as the angiosperms. They the most advanced, diverse and abundant group of plants in the world and include around 200,000 plant species.

Gymnosperms are a group of woody, vascular plants with seeds but without flowers or fruit. The seeds of gymnosperm plants sit exposed on cones rather than enclosed in a fruit as they are with angiosperm plants.

Ferns and lycophytes are two groups of vascular plants without wood, seeds or flowers. They include over 12,000 species from ancient groups that once dominated the forests in many parts of the world.

The non-vascular plants include mosses, hornworts and liverworts and some algae. They are generally small plants limited in size by poor transport methods for water, gases and other compounds.

Plant physiology encompasses the study of plant form and function. As plants evolved to life on land they were required to evolve methods to extract CO², light, and water from the atmosphere and soil.

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