Taxonomy and Systematics

Humans have named things of importance to us since the dawn of communication (eat this, run from that...) But how do scientists organize living things and what are the levels of organization they use to describe relationships between groups? Aristotle and Linnaeus take starring roles here, but there's a lot they got wrong.

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VIDEO DETAILS
Taxonomy and Systematics
Taxonomy (G taxis: arrangement; nomia: method) is the discipline of defining groups of biological organisms on the basis of shared characteristics

Hierarchical groups help us to identify related organisms and also describe evolutionary relationships

Aristotle
To understand anything, one must classify it according to it's parts
Classified all animals into two groups: blooded and bloodless

Pliny the Elder

Carl Linnaeus
Systema Naturae 10th ed. in 1758
Binomial Nomenclature

Where do the Names Come From?
Latin (Classical or Medieval)
Classical Greek
Names of People
Names of Places
Other Languages

What's In a Name?
Morphologic Characters
General external morphology
Special structures
Internal morphology
Embryology
Karyology and other cytological factors
Physiological Factors
Metabolic factors
Body secretions
Genic sterility factors
Molecular Characters
Immunological distance
Electrophoretic differences
Protein sequences
DNA hybridization
DNA and RNA sequences
Restriction endonuclease analyses
Other molecular differences
Behavioral Characters
Courtship and other ethological isolating mechanisms
Other behavior patterns
Ecological Characters
Habitats and hosts
Food
Seasonal variations
Parasites
Host reactions
Geographic Characters
General biogeographic distribution
Sympatric-allopatric relationship of populations

Levels of Organization
Linnaeus' Domains
Linnaeus Described Six Classes of Animals
Heart with 2 auricles, 2 ventricles. Warm, red blood
Viviparous: Mammalia
Oviparous: Aves
Six Classes of Animals
Heart with 1 auricle, 0 ventricles. Cold, puss-like blood
Have antennae: Insecta
Have tentacles: Vermes
Hierarchy of Similarities

Modern 3-Domain System
Domain
Kingdom
Phylum (= Divisions in Botany)
Class
Order
Family
Genus
Species
Example: The Dog

Problems...
Linnaeus (and everyone else) wondered about where these species came from and how to define a species

Linnaeus treated species as immutable

Georges-Louis Leclerc, Comte de Buffon
Compared living and fossil mammals (elephants and mammoths)
He did not see how organisms could cross inhospitable boundaries to reach suitable environments
He found different kinds of animals and plants in very similar, but completely isolated environments

Age of Enlightenment
Paleontology and the discovery of extinct species in the fossil record began to undermine the static view of nature which had persisted since Aristotle
Species are NOT Fixed Entities

Taxonomy and systematics is a dynamic science

[joefelraymundbosque]

The way she discuss is a hundred times better than my teacher. REALTALK.

[sgarcata]

Loved this... she has such a mellow voice of convincing authority... pleasure to listen to

[EdGloss]

Maybe it's just me but I found taxonomy to be incredibly interesting and informative and one of the concepts that helped to really drive home and solidify evolution and common ancestry.

[ninjachicken]

you have truly changed my life. I really felt like i could relate to the penguins, especially the one who was missing its head. the video was a great metaphor for the threat that western capitalism poses to the wellbeing and survival of penguins everywhere. i will never forget the kindness that you brought to my life when you posted this. How can i repay you ? i cannot possibly repay this service that you have done for me. I was especially touched by the part where the video started. This video has saved my life and so many others by reminding us to eat food and drink water. however, my one issue with this video was the fact that it was not converted into a broadway musical production: surely something so full of passion and controversial truth should be able to be seen and experienced by millions of others! truly this work of art brings as much music to people as beethovens fifth symphony. the power of this video can move mountains

[CakeTastey]

GREAT video (*very* clear)
I don't even study science as a secondary, I just like to learn new things--- and this video has sparked an interest in biology/taxonomy in me!
Thank you for your hard work!

[Dawnofthehead]

For an understanding of modern taxonomy and systematics, you cannot leave out cladistics. If you go to a biology conference, almost everyone there will be using cladistics for systematics. Cladistics won the "taxonomy war" a few decades ago. Most biologists now are cadists, meaning they hold to that a phylogeny must be monophyletic and that paraphyletic and polyphyletic groupings are unscientific. This video is accurate for almost everything up to the 1980s.

[London_Exhibitions]

I recommend your videos to all kids I encounter who are interested in science,
Keep up the good work!!

[alis.]

This is the best AP biology study channel in the whole you tube +1 from me

[t.damianboyle]

This is an outstanding instructional presentation. A reference standard for all Instructors to aspire to. Big time thanks!

[SoundForStudy]

Just to point out, the video was amazing! very good job and very informative, but one corrigendum, there does exist a convention for naming animals with a set of rules the way chemists do, it is called the Internation Code of Zoological Nomenclature and it dictates the rules and requirements for naming animals.

[aakashsharma]

thanks for melting the mountain of questions inside my head... very nice video

[geogre]

Amazingly insightful, thank you for this

[AcanLord]

Solid video.
Useful for studying purposes.

[jeffreyjhouser]

Excellent video! Very informative and well presented!

[jeunebienah]

I LOVE THIS VIDEO! Hope i'll pass my exams tommorow :)

[AcanLord]

Protists are being found to be polyphyletic.
its actually a bunch of different kingdoms bunched together
that dont really have much in common.

[dicksonnsiahministries]

kudos to you...nice video and very educative

[snoopy]

Great video you really explained it very clearly!

[saishakarbhari]

this video has really been very helpful....

[GrigorisDeoudis]

Nicely done! Came here by looking for the definition of 'type specimen'. After two years of keeping and learning about succulents, plant systematics are still difficult to digest for me, a Greek guy that has an advantage of knowing what all these Greek words mean. Plus, I love Latin language and the pronunciation of these - for some - complex binomial names. So, I have just landed here, I am going to hit the subscribe button and if there's no video about the 'type specimens' (one that can make it very clear, for example, what means "designing a holotype") it would be great if you can make one.
Thanks again!