How would i describe a Cladogram as paragraph?

How would i describe a Cladogram as paragraph?

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I have this paragraph that i have halfway finished, but i do not know what to put in the spaces.

A Cladogram is a branching diagram that represents the proposed phylogeny or evolution of a species or a group. The groups used in Cladograms are called clades… To construct a cladogram, two characters are defined. Then the outgroup of various species are identified based on the sequencing or closeness of the derived characters in the clades. In making a cladogram, ______ assume that groups that _____ more derived characters have a more close common ancestor.

The letters that are italicized are words that i think are correct. This paragraph is needed for part of a recite that i have to do in front of my class. The prof. gave me a page like this. And I don't know what those spaces are. Can someone help me… please?

I provided some edits in my comment -- hope the following clarifies things for you a little bit.

To construct a cladogram, two characters are defined.

You may be confusing character and character state. It's valid to have a cladogram with a single character (e.g. the single character, "warm-blooded"), but you will need at least two character states to infer a non-trivial cladogram. The states for the character warm-blooded would be Yes or No.

A molecular example would be a cladogram inferred from a column of a sequence alignment. That column is the character, and for, say, DNA, the character states are the set {A,C,G,T}.


The outgroup is specified by you, the investigator. It's typically a hypothesis (viz. model parameter), which is either a guess or is based on some external evidence.

In short, the analysis starts from character-state data for some number of taxa ("species" in your paragraph). From this data you are selecting (constructing) a tree-topology that best fits this data.

E.g. for four taxa, labeled A,B,C,D, with D the outgroup, the process is like:

start --> cladogram ABC(D) A B C (D) / / / / / /

There are many different methods to construct the cladogram. One popular method is maximum parsimony, but the assumptions of that model are severe. However, any method is effectively selecting a tree topology out of all the finitely-many possible tree topologies over N leaves, where N is the number of taxa (species) in your investigation.


In this sentence, you seem to be expressing a relationship between the number of shared derived characters (synapomorphies) for a given clade, and the common ancestor of that clade.

This can be very confusing, maybe an example will help. Let me annotate the above tree with a binary character, having states + and -.

+ + - - A B C (D)  / / / + / / / / - / / -

The idea is that the ancestral state for the entire group is -, as was the state for the ancestor of {A,B,C}. However, the + state was derived after the ancestor of {A,B,C} but before (or "in") the ancestor of {A,B}. Then it was passed to the terminal units, A and B. (Note: typically you don't have this ancestral-state information, only the information at the tips of the tree. You're actually inferring the ancestral states and topology from the data at the tips.)

I would claim that, in general, taxa that share more derived character (states) have a more recent common ancestor than taxa that do not. Although, this can be confounded by homoplasy.


Which statements best describe the cladogram? Select THREE options.

A-Reptiles are the most primitive.

B-Birds and reptiles are most closely related.

C-Frogs are more closely related to fish than birds.

D-Frogs are more closely related to birds than fish.

E-Fish are the most primitive.

2-Kelli drew a diagram to compare cast and imprint fossils.

(A diagram with 2 circles connected, one labeled Cast and one labeled Imprint. The y is located in the middle of where the 2 circles combine.)

Which label belongs in the area marked Y?

A-Involves minerals replacing remains of organism
B-Takes millions of years to form
C-Gives evidence of organism's activity
D-Involves mold filling with minerals and sediment

3-A scientist observes fossil evidence that leads her to believe that certain organisms have a common ancestor.
(There's no context lol.)
Which observation most likely led to this conclusion?

A-She observed older fossils that contained many of the same minerals as the newer ones.
B-She found skeletons of modern organisms in the same area as fossilized organisms.
C-She observed a fossil with skeletal structures similar to certain modern organisms.
D-She found several fossils in rock layers directly below other fossils of similar size.

It can be seen on a cladogram that modern birds and reptiles share a common ancestor. select the piece of evidence that best supports this idea. a) reptiles are also related to mammals. b) birds have evolved into many groups. c) feathers are a derived characteristic that first evolved in reptiles. d) birds have the derived characteristic of being warm blooded, like mammals.

The feathers can be a very good factor to compare both cladograms, once these feather can easily be found in primitive reptiles. Once we find a common characteristic, it's time to analyze the evidence by comparing both cladograms and see where these species, the birds and the reptiles, had a common ancestor, and if that's possible, other characteristics can be analyzed easily.

The correct answer is - C) Feathers are a derived characteristic that first evolved in reptiles.

Nowadays it is widely accepted that the reptiles share a distant common ancestor, and that can be seen from multiple evidence, one of which is the evolution of the feathers, and surprisingly, it is the reptilians that developed them first, or rather, the dinosaurs. It was thought until recently that the dinosaurs have scaly skin as the modern reptiles, but multiple evidence came out that proved that big portion of the dinosaur species, especially the bipedal ones, were actually partially, or totally covered with feathers.

As the birds evolved from this types of dinosaurs, the connection is pretty clear. Add on that the structure of the bones which is pretty much identical to some of the dinosaurs, and also the evidence of transitional species from reptilians to birds, it is certain that the birds have their ancestry in the reptilians in the distant past.

The Hive Mind

To quote Bender from Futurama, “I’m back, idiots!”. It was a nice little holiday on the Cote d’Azur, but right now I want to talk about brains. Our brains, specifically.

At the beginning of the summer I had read on some generic weekly magazine a small paragraph about how some scientists thought that human beings pushed the evolution of intelligence to its limits: in other words, they said that we couldn’t become smarter, because we peaked. My first thought was “Yeah, bullshit” because that wasn’t a scientific magazine, and it seemed like the classical vague anthropocentric article about how we are the best, and the somehow intended ending of the evolutionary project. And let me clarify this, as awesome as we are, we’re not THE best. There’s not such a thing as the absolute best in evolution. Some organisms are more adaptable than others, some have better instruments to survive in a specific habitat or more habitats (and mind you, the habitat can always change), but we’re just a small, successfull and still evolving (as every living thing) branch of the enormous Tree of Life. There are many species of bacteria, arthropods, worms, fungi, etc… that are much more successfull than us, so while our species is clearly one of the most successfull vertebrates EVER, it’s by far not the most successfull organism of all time. But I digress.

What I could concede to that small paragraph was that certainly in modern times the selective pressure necessary to “push us” to an even superior intelligence is pretty low. We were able to create awesome technology and modificate our environment to make survival easier, and in our (western) society everybody can access at least the most basic of those advantages the creations of smart people are enjoyed by everyone, and thus smart people and less smart people have the same chances of survival. But this didn’t convince me that we didn’t have at least the potential to evolve in something smarter.

Anyway,the last issue of Le Scienze (italian name of Scientific American) contained an article about the fact that we may have indeed reached the limit of intelligence for a single organism, and I guess it was the same article referenced in that small paragraph I had read months before. Actually the article (by Douglas Fox) suggests that, while there might be ways to improve our brains, the costs in terms of energy and space (remember the joke about planet sized heads? yeah, you don’t want one of those) would be too high to justify them, so the modern version of our brain might be the near-perfect, most functional compromise. I don’t know if this is true, but certainly this is an explanation that I can accept better than “We’re so awesome, nothing can beat us”: after all, physical limits like this are the cause of many “imperfections” in the world of biology. Organisms are not magical, and even when they adapt the best they can to their environment, they must still obey its laws, and the laws of the matter they’re composed of. As Stephen Jay Gould pointed out, the best evidence for evolution isn’t the perfect adaptation, but these small imperfaction caused by the fact that life must build new forms from the parts it already has – it can’t start again from blank to create better components for a completely new organisms.

While the focus of Fox’s article are the details about the limits that prevent us from becoming smarter, it concludes briefly hypothesizing a way in which humanity could become more intelligent, and the most promising tool to realize this ideal is – brace for it – the Internet! HA, suck it, Internet haters.

The point is that certain organisms that act in a pretty “stupid” way individually form colonies which have a much better decisional ability and can act in an extremely efficient way for their own survival. The most famous example of this are social hymenopterans like ants and bees, insects that embody the definition of eusociality: the labor is divided among specialized castes (queen, males, workers, warriors… it depend on the species) and every individual is actually just a small part of the entire, huge, collective organism, just like a single cell is just a small functional part of a body or a brain. And it’s this collective entity that takes decisions and shows complex behaviours. Other eusocial animals include termites (Isoptera) and even mammals like the nightmarishly ugly and yet strangely fascinating Heterocephalus glaber, the naked mole rat. And animal eusociality is not the only, or even the first, example of organisms cooperating to “become smarter”: bacteria do that too. Everybody knows bacteria are single-celled organisms most of them however form colonies capable of feats that are impossible for isolated bacterial cells. Bacteria colonies can decide if the environmental conditions and resources would allow them to grow (quorum sensing) and coordinate their metabolism thanks to special biomolecules used by the cells to communicate with each other they can form biofilms in favourable environments, to protect and anchor themselves colonies of Rhodospirillum centenum are capable of phototaxis (they are photosyntetic bacteria that move towards the light source) while single cells of the same species are incapable of doing so.

So the point is that, even though we are animals with a strong individual personality (well, some of us are, at least), we’re still social animals, and communication can make our population smarter and more efficient than the sum of its parts. We do this since the dawn of our species, with spoken words, and then written words, and now we can do it globally thanks to the internet. The fact that shared knowledge is a lot more vast than the knowledge of a single man is obvious, as it’s obvious that labour division and coordination made us a lot more efficient in a lot of different tasks. Are we really going to become a single planetary superintelligent supercolony? Would this really be an advantage to us? Nowadays individualism and egoism are rampaging everywhere, and so it may seem highly unlikely, and to some even scary, the possibility that society will prevail on the individual, and yet globalization and mass communication make us march everyday towards that possibility. We’ve already prooved to be strange animals: big primates who give birth only a few times in their lifetime (K strategy) and yet we managed to become one of the most widespread mammals on the planet, thanks to our intelligence and cooperation. So it may be possible the paradox of the animal with the most complex individual personality that, while retaining said individuality, becomes part of a global coordinated hive mind. I don’t know how far this process will go, if it’ll be enough to save us from ourselves and if it will influence our biological evolution. What I know is that, while some people think that globalization is evil, to me it only means that everyone in the world will have access to the same medicines. So what the hell, let’s give it a shot.

Intro to cladistics

What is a clade? How can we explain analogous and homologous traits using cladograms? What do we need to know about cladograms? All these important questions are covered in this lesson plan using a variety of materials including short presentations and online resources. There are plenty of questions for students to answer.Carry out this Cookies cladograms activity. A fun activity to illustrate the way that cladograms.



Phylogenetic Classification

Linnaeus classified organisms based on obvious physical traits. Basically, organisms were grouped together if they looked alike. After Darwin published his theory of evolution in the 1800s, scientists looked for a way to classify organisms that showed phylogeny. Phylogeny is the evolutionary history of a group of related organisms. It is represented by a phylogenetic tree, like the one in Figure below.

Phylogenetic Tree. This phylogenetic tree shows how three hypothetical species are related to each other through common ancestors. Do you see why Species 1 and 2 are more closely related to each other than either is to Species 3?

One way of classifying organisms that shows phylogeny is by using the clade. A clade is a group of organisms that includes an ancestor and all of its descendants. Clades are based on cladistics. This is a method of comparing traits in related species to determine ancestor-descendant relationships. Clades are represented by cladograms, like the one in Figure below. This cladogram represents the mammal and reptile clades. The reptile clade includes birds. It shows that birds evolved from reptiles. Linnaeus classified mammals, reptiles, and birds in separate classes. This masks their evolutionary relationships.

This cladogram classifies mammals, reptiles, and birds in clades based on their evolutionary relationships.

Paragraphs on Bioaccumulation (With Diagram)

The term bioaccumulation is used to refer to storage of a pollutant at levels higher than found in the environment.

Many chemicals including dioxins, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organ metallic forms of metals bio-accumulate in animal fat (Hill, 1997) and are difficult to degrade.

Lead and fluoride bio-accumulate in bones. Chemicals bound to proteins and cadmium can bio-accumulate in the liver, kidney and other tissues. The route of almost 90% of human exposure to PAHs is from food consumption, especially the leafy vegetables and unrefined grains.

Breathed into the lung as fine particulates, PAHs can cause respiratory problems and a number of them are carcinogens. Cadmium bio-accumulates in the kidney and the amount of this toxic metal stored in this organ increases with age. Cadmium can also accumulate to high levels in liver Organ chlorine pesticides have low solubility in water they are highly soluble in lipid materials, including animal fat, in which they bio-accumulate to high levels.

The term bioaccumulation is also used to describe increase in quantity of a chemical through the food chain. For example, in a food chain— phytoplankton zooplankton -> small fish -> large fish eating birds – each component of the food chain receives some chemical from the environment (bio-concentration) but the amount of chemical becomes several times more through the food chain and organisms at the top of the food chain are worst hit as they contain the maximum quantity of the harmful chemical. Through this route pesticides sprayed on crops accumulate in vegetables food grains, fish and human tissues (Fig. 8.1).

Bioaccumulation is more marked with some chemicals than others. For example, organ chlorine pesticide, DDT is stored in the body fat for a much longer time than methoxychlor. The half-lives of these insecticides in rats are 6-12 months and 12 weeks respectively (Lu and Kacew, 2002).

Writing Reviews in Biology

The summary is very brief -- about 1 sentence per main section in the review paper. After all, the reader has just spent time reading all the detail. The summary serves as a reminder of the most important "take away" point in a section. In many reviews, the evaluation of the literature is remarkably similar to the recommendations, and reads something like "Further investigation is warranted."

What about critique?

Recall from the initial discussion of Review papers that these publications make two kinds of contribution: 1) an organized summary of the current state of an area of research 2) critical commentary from the writer who eventually recommends directions for further research.

There are two ways of furnishing critical commentary. First, critique may be provided at the end of each topical subsection. Sometimes, recommendations are also provided, especially if the Review is particularly complex. Second, all critique/recommendations are saved for the conclusion. Which is the best pattern? As always, consider the reader. The more complicated the reading task, the more difficult it is for the reader to absorb the writer’s message. If the topical subsections are very straightforward, with little controversy/conflict involved, then it’s okay to save all critique/recommendations for the end of the paper. More often, the topics are not so straightforward. In that case, it is easier for the reader (and also for the writer) to finish each section with the writer’s critical evaluation of the material. In this manner, each topical subsection reads like a fairly complete mini-essay the reader can pause, grab a cup of coffee and a Snickers, and return to the review without sacrificing comprehension.

How does all of this relate to the conclusion? In a review paper, the conclusion is a short, up-front piece of writing. First, the conclusion offers a brief review of the main ideas of each topic subsection (generally, only a single sentence long) – this is the summary function of a conclusion. Second, the conclusion finishes with critique + recommendations or just recommendations. If the critique is provided in the body of the paper, then the conclusion need only consist of a summary paragraph and a recommendations paragraph. Some writers even combine both of these into a single paragraph.

Thus, your conclusion will depend partly on the decisions made about critique. If critical evaluation is provided in the body of the paper, it need not be repeated in the conclusion. If critical evaluation is not provided in the body of the paper, then it is provided in the conclusion.

Critique in Body of paper –

All critical evaluation comes at the END of a subsection. If you find yourself logically needing to provide some critique before continuing on within a particular section, then you need to create a second-level subsection (a subtopic within your main topic subsection – for the visual thinkers, these are the main connections coming off a central hub). Keep in mind: the prime directive here is that all critical evaluation is written in a separate paragraph at the end of a section.

Thus, the Conclusion consists of the summary + recommendations for further research.

Critique in Conclusion of Paper – there are two organizational patterns

#1 – The first paragraph is summary, second paragraph is critique, third paragraph is recommendations (note: second paragraph is more properly understood as a functional section as you may need more than one paragraph!)

#2 – Each paragraph consists of summary of a particular section, the critique for that section, then the recommendations for that section. The number and order of paragraphs parallels the number and order of main topical sections of the paper.

Let's look at an example From Dynamics of Multiple Signalling systems.

The evolution of multiple signals through dynamic selection merits distinction from static evolutionary hypotheses because of the fundamentally different implications for the maintenance of genetic variance and the operation of sexual selection. However, dynamic hypotheses are not easily subsumed within the established theoretical framework for explaining the adaptive value of multiple signals. // This framework is based on the redundancy of signal components ( Table 1 a), but under dynamic selection, signal redundancy is context-dependent ( Table 1 b). This difference furthermore underscores the limitation of the common methodological approach where receiver responses to signal components in isolation are compared with responses to the multi-component signal [61] : if receiver reactions are context-dependent, such studies do not clarify the adaptive value of the system unless they are carried out in multiple environments [47] . // I therefore advocate the explicit recognition of dynamic selection in formal hypotheses, which will hopefully encourage field studies and laboratory experiments to be designed appropriately for the detection of context-dependence ( Box 4 ). Indeed, the possibility that context-dependence of signal content and receiver preferences is widespread calls for multiple signalling systems, which have previously been ascribed to static selection regimes by default, to be revisited.

// -- main assertion and motivation for review -- from introduction section "The Ubiquity of Multiple Signalling"

Systematics, Taxonomy, and Classification: Alternative Methods of Classification

The Linnaean binomial system of classifying animals brought organization from chaos but recently, with the application of modern technology, new methods have surfaced that yield additional information. Methods of establishing ancestral kinship are helpful in establishing new taxonomic procedures that often relate species in new ways. Although no one method is without drawback, each offers unique insights and information in reference to the organisms in question.

Cladistic Analysis

Cladistic analysis is probably the most widely used alternative method. Cladistic analysis is a means to classify organisms to match their evolutionary history. Common phylogenetic features are used to establish relatedness between organisms with the help of sophisticated computer programs that quickly sort organisms according to shared evolutionary structures.

Cladistic analysis sorts homologous structures into either a primitive character or a derived character. Primitive characters establish the broad classification that generates the basic grouping of organisms. For instance, a cladistic primitive character for plants is the presence of chloroplasts. Those organisms that contain chloroplasts are clumped into the same large grouping.

Derived characters are also homologous structures, but they represent features that have been modified for specific functions. Derived characters are more unique than primitive characters and tend to sort organisms by their presence or absence in the organism. The presence of a derived character or set of derived characters establishes a greater degree of relatedness. The more derived characteristics organisms share, the greater their degree of kinship. For instance, a derived characteristic in plants is the presence of vascular tissue. Advanced plants contain vascular bundles, but simple aquatic plants do not. This relatively simple anatomical feature demonstrates the vast difference between vascular and nonvascular plants. Review the example that follows to distinguish primitive and derived characters in mammals.

Mammalian primitive characters:

  • Appendages modified for aquatic movement (for example, whales)
  • Appendages with an opposable thumb (for example, humans)
  • Appendages designed for running (for example, dogs)
  • Appendages designed for grazing on uneven ground and carrying heavy body weight (for example, cows)

After the primitive and derived characters are known, a cladogram can be constructed to show evolutionary linkages between groups of animals. Examine the illustration Simple cladogram.

This cladogram shows the evolutionary relatedness of major plant types by using simple derived characters on the right side in ascending order. Organisms located next to each other horizontally across the top are more related than those not in close proximity. For more specific classifications, such as the kinship between an oak tree and an elm tree, the cladogram would need more specific derived characters.

The cladistic model is somewhat similar to previous models of organization, except for several notable differences. The one most widely reported is the cladistic location of birds on a cladogram in relation to the reptiles. A cladogram relates birds closer to crocodiles and dinosaurs than to snakes or lizards. Interestingly, it is now known that reptiles did not evolve from a common reptilian ancestor, but are more likely descended from several different ancestors, making the reptile classification a conglomeration of animals with similar characteristics but dissimilar backgrounds! The cladogram correctly shows the hereditary linkage between birds and certain reptiles. It clearly is different from classical taxonomic classifications, which place all reptiles in one category (Reptiles) and all birds in another (Aves).

Cladistic analysis is extremely objective: The organism either has the feature or not. This strength is also a weakness. Opponents charge that the technique does not account for the amount or degree by which a feature is present or is utilized. In their opinion, this omission ignores too much relevant data and fails to make an accurate assessment of the difference between groups. For example, the fact that penguins have wings but do not use them to fly would create a cladistic analysis problem.

Evolutionary Systematics

A contrast to the no-bias approach of the cladistic analysis approach, the evolutionary systematic method deliberately builds in observer judgment. These taxonomists place heavier emphasis on the observed use or nonuse of a structure as well as the way it is used. Judgments are based on direct observation regarding the degree of evolutionary importance a particular feature is to that organism. For instance, in the previous bird and reptile analogy, the evolutionary systematic approach would lend more importance to the presence or absence of feathers than the derived homologous characteristics. So birds would be classified separate from reptiles. Most taxonomists agree that in the absence of data, the cladistic model is superior with adequate data, the evolutionary systematic model has advantages.


Phenetics classifications are somewhat similar to evolutionary systematics in that both include all available data regarding the study of organisms and both are antagonistic to the cladistic analysis model. Phenetic classification does not attempt to establish evolutionary linkages but simply the clumping together of organism based on ?overall? degrees of similarity. Phenetic classification requires access to the most data. Its overall effectiveness is diminished when the data are incomplete.

Shared Characteristics

Organisms evolve from common ancestors and then diversify. Scientists use the phrase “descent with modification” because even though related organisms have many of the same characteristics and genetic codes, changes occur. This pattern repeats over and over as one goes through the phylogenetic tree of life:

  1. A change in the genetic makeup of an organism leads to a new trait which becomes prevalent in the group.
  2. Many organisms descend from this point and have this trait.
  3. New variations continue to arise: some are adaptive and persist, leading to new traits.
  4. With new traits, a new branch point is determined (go back to step 1 and repeat).

If a characteristic is found in the ancestor of a group, it is considered a shared ancestral character because all of the organisms in the taxon or clade have that trait. The vertebral column in Figure 1 is a shared characteristic. Now consider the amniotic egg characteristic in the same figure. Only some of the organisms in Figure 1 have this trait, and to those that do, it is called a shared derived character because this trait derived at some point but does not include all of the ancestors in the tree.

The tricky aspect to shared ancestral and shared derived characters is the fact that these terms are relative. The same trait can be considered one or the other depending on the particular diagram being used. Returning to Figure 1, an amniotic egg is a shared derived trait for amniotes as a clade, because the immediate ancestor of amniotes, as well as other groups descended from the ancestor of amniotes, do not have it. However, it is a shared ancestral trait for any particular group of amniotes, such as the lizard, rabbit, or human (shown in Figure 1) because they all stem from an ancestor with that trait. These terms help scientists distinguish between clades in the building of phylogenetic trees.

Choosing the Right Relationships

Imagine being the person responsible for organizing all department store items properly—an overwhelming task. Organizing the evolutionary relationships of all life on Earth proves much more difficult: scientists must span enormous blocks of time and work with information from long-extinct organisms. Trying to decipher the proper connections, especially given the presence of homologies and analogies, makes the task of building an accurate tree of life extraordinarily difficult. Add to that advancing DNA technology, which now provides large quantities of genetic sequences for researchers to use and analzye. Taxonomy is a subjective discipline: many organisms have more than one connection to each other, so each taxonomist will decide the order of connections.

To aid in the tremendous task of describing phylogenies accurately, scientists often use the concept of maximum parsimony , which means that events occurred in the simplest, most obvious way. For example, if a group of people entered a forest preserve to hike, based on the principle of maximum parsimony, one could predict that most would hike on established trails rather than forge new ones.



Watch the video: 3-25 AP18 How to make a Cladogram (August 2022).