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Morphological traits, such as those used to construct the cladogram above, can be preserved in the fossil record, but DNA generally is not preserved. However, since we know that your DNA was inherited from your parents, and your grandparents, etc., we can predict that DNA sequences from related individuals would contain evidence of that relatedness. These sorts of “molecular fossils” can be used to produce and refine cladograms, generating the structures we know as phylogenetic trees.

“this view of life”

It is important to also understand that phylogenetic trees are nested hierarchies , i.e., any individual set of branches is also part of a larger set of branches. This is easily seen in the accompanying figure ( [link] ). The clade containing the eagle and the alligator nests within a clade that also contains the antelope, and that clade nests within another clade, and another, etc. The hypothesis of descent with modification (i.e. evolution) absolutely predicts that the evolutionary history of organisms would be represented by a set of nested hierarchies. Cladistic analyses, particularly those based on DNA sequences, give results consistent with this prediction of Darwin’s theory.

Cladogram showing the nested hierarchical arrangement of organisms predicted by Darwin's theory of evolution.

If we continue backward in time from any tip of any branch of the phylogenetic tree above, we soon realize that all of these clades have a common ancestor at some point in the distant past. DNA evidence supports and strengthens this interpretation. As a matter of fact, the observation that all life forms on the planet have DNA as their genetic material is further support of this interpretation. The details of the arrangements of the various branches may change, as new observations are included in the analyses of relationships. The figure below ( [link] ) shows various phylogenetic trees that have been used in the past. Note that the fundamental conclusion, that all life on this planet came from a common ancestor, is a constant feature of all of these trees. Indeed, as new observations are made, particularly in the realm of DNA sequence data, this conclusion has become increasingly well-supported.

Various depictions of the Tree of Life. These hypothesized trees reflect the state of knowledge at various times in the past. As new observations are made, new phylogenetic trees are constructed to accommodate that new knowledge. It is clear, from this example alone, that scientific hypotheses change in response to new discoveries and new knowledge. The currently accepted Tree of Life (Figure 8, below) will undoubtedly be modified in response to new scientific discoveries in the future.
The Tree of Life. The currently accepted hypothetical relationships between the three domains of living things. Bacteria, Archaea, and Eukarya (eukaryotes like you and me) are all thought to be descended from a common ancestor that lived billions of years ago. Image credits: Anthrax bacteria, from John A. Jernigan et al, "Bioterrorism-Related Inhalational Anthrax: The First 10 Cases Reported in the United States". Emerging Infectious Diseases 7(6), December 2001. Pyrococcus furiosus , from Wikimedia Commons. By Fulvio314 (Own work) (http://creativecommons.org/licenses/by-sa/3.0) Stentor, copyright-free image from the Protist Image Database.Mushroom, warbler, and eryngo are used with permission of the photographer, David A. Rintoul.

The most widely accepted scheme has all living forms divided into three major Domains, Bacteria , Archaea , and Eukarya . The evolutionary relationship between these largest taxa is shown above ( [link] ). Note that current data support the idea that the Eukarya (including me and you) are more closely related to the Archaea than they are to the Bacteria; Archaea and Eukarya have a more recent common ancestor compared to Bacteria and Eukarya. Each of these Domains can be further subdivided into Kingdoms, Phyla, Classes, Orders, Families, Genera, and Species. For example, humans ( Homo sapiens ) are in the Domain Eukarya, Kingdom Animalia, Phylum Chordata, Class Mammalia, Order Primates, Family Hominidae, Genus Homo , and Species sapiens . In some cases these classifications are further organized into taxa such as Superfamily, or divided into taxa such as Suborder, but those are details that need not concern us here.

Indeed, the entire Tree of Life is a nested hierarchy. We’re all related. Darwin suspected this, and his theory predicted the phylogenetic trees that scientists have generated from the observations and other data available to us. In one of the most often-quoted passages from the Origin , he demonstrates the sense of wonder that all biologists have when contemplating the diversity of living forms.

"There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved." - Charles Darwin, 1859.

Questions & Answers

how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
Idrissa Reply
im all ears I need to learn
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what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
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Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Principles of biology. OpenStax CNX. Aug 09, 2016 Download for free at http://legacy.cnx.org/content/col11569/1.25
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