What is Cladistics in taxonomy?

What is Cladistics in taxonomy?

Cladistics (/kləˈdɪstɪks/, from Greek κλάδος, kládos, “branch”) is an approach to biological classification in which organisms are categorized in groups (“clades”) based on hypotheses of most recent common ancestry. Cladistics is now the most commonly used method to classify organisms.

Why is the outgroup needed on a Cladogram?

The outgroup is used as a point of comparison for the ingroup and specifically allows for the phylogeny to be rooted. Because the polarity (direction) of character change can be determined only on a rooted phylogeny, the choice of outgroup is essential for understanding the evolution of traits along a phylogeny.

How do you do a Cladogram?

  1. Step 1: Pick Organisms for Your Cladogram.
  2. Step 2: Pick One Ancestral and One Derived Characteristic to Designate the Outgroup.
  3. Step 3: Pick Derived Characteristics for the Ingroup (Part 1)
  4. Step 4: Pick Derived Characteristics for the Ingroup (Part 2)
  5. Step 5: Pick Derived Characteristics for the Ingroup (Summary)

What is Apomorphic character?

An apomorphy is a character that is different from the form found in an ancestor, i.e., an innovation, that sets the clade apart from other clades. A synapomorphy is a shared apomorphy that distinguishes a clade from other organisms.

What is shared ancestral character?

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 same trait can be considered one or the other depending on the particular diagram being used.

What is the difference between a shared ancestral character and a shared derived character?

An ancestral character is shared with the species ancestral to more than one group: it can lead to different groups being classified together. A shared derived character is shared by the ancestral species and a single group: it is the only reliable guide to inferring phylogeny.

Why is hair a shared derived character?

Among mammals a backbone is considered a shared ancestral character because it was present in the ancestor common to all mammals. Hair is a shared derived character because it is unique to mammals.

What two domains are most closely related?

Recent evidence indicates that Archaea and Eukarya are more closely related to each other than either is to Bacteria. According to the evidence, all three domains of life share a common ancestor that probably existed more than 3 billion years ago (bya). Two lines of descent emerged from this ancestor.

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