Editing 2269: Phylogenetic Tree

{{comic
| number    = 2269
| date      = February 17, 2020
| title     = Phylogenetic Tree
| image     = phylogenetic_tree.png
| titletext = And I was kicked out of my March Madness pool because I wouldn't shut up about the evidence for NBA/ABA endosymbiosis.
}}

==Explanation==

In biology, {{w|phylogenetic tree}}s are a way of showing evolutionary relationships between species. Each split in the tree represents a species that was the common ancestor of the two species beneath it, resulting in a bifurcating structure that can be followed all the way back to a single root - the most recent common ancestor of all species in the tree.

In sport, a tournament tree is a diagrammatic way of showing the progress of competitors in an elimination tournament. Each split in the tree represents the winner of a match between the two competitors beneath it. This too results in a bifurcating tree structure, which eventually terminates at a single root representing the champion of the tournament. [[:Category:Tournament bracket|Tournament brackets]] are a recurring theme at xkcd. 

In this comic, Randall has taken advantage of the similarity between these two diagrams in order to prank his fellow biologists.

Each year in the United States, in March and early April, 68 {{w| National Collegiate Athletic Association}} (NCAA) Division I {{w|college basketball}} teams play in a {{w|single elimination}} postseason tournament to decide the national champion of college basketball. This tournament is colloquially known as {{w|March Madness}}. Associated with this tournament, it has become commonplace to guess the outcomes of each game, and predict who will win the tournament. A diagram illustrating the progress and elimination of teams through the tournament is called a {{w|Bracket (tournament)|bracket}}. Presumably Randall is referring to the men's college basketball tournament here, though there is a separate women's college basketball tournament that is also referred to as "March Madness".

[[Randall]] has replaced the trees in a biology paper with a basketball {{w|March Madness pools|March Madness bracket}}, which is not related to biology. The 2019-20 NCAA college basketball regular season had not ended yet at the time of this comic's publication, so the partial bracket shown is a fictional bracket. Compared to a phylogenetic tree, the 'root' of a tournament tree is the final result (once known), rather than the common ancestor that was prior in time to all those that came after; the 'leaves' are all the initially hopeful competitors, rather than the latest extant (or unsucceeded extinct) organisms.

The title text shows the inverse of what the comic says: Apparently the March Madness bracket pool removed Randall after he tried to introduce biology-related evidence comparing the {{w|National Basketball Association}} (NBA) and {{w|American Basketball Association}} (ABA) to organisms and claiming the ABA is an {{w|endosymbiont}} living inside the NBA. An endosymbiont is an organism living inside another organism. In a way, this can be considered true of these two leagues, as the NBA and ABA {{w|ABA–NBA merger|merged}} in 1976 after which the ABA ceased to exist. 4 teams from the ABA, the {{w|Denver Nuggets}}, {{w|Indiana Pacers}}, {{w|Brooklyn Nets}} and {{w|San Antonio Spurs}}, continue to exist today as NBA teams. It is additionally humorous that Randall brings up the ABA/NBA merger in a March Madness bracket group, as March Madness is a college basketball tournament, as opposed to professional basketball played by the NBA and ABA.

A March Madness bracket was also the topic of [[1819: Sweet 16]].

===Teams shown in the bracket===
The bracket shows the Duke University basketball team winning the NCAA college basketball tournament. Strangely, it shows Gonzaga University linked only to explicitly non-Gonzaga branches, suddenly appearing out of the bottom section, which is not possible in a sports bracket context, but possible in biology if Gonzaga is an identified ancestral root with all descendant evolved species identified by a new term. In fact, the implied unchanged continuity of Duke from 'universal ancestor' to niche population sharing the world with all of its diverged and re-evolved outbranchings (rather than perhaps used as a term for a typically broad cladistic group of branches, such as Archaea) would be more curious - or just imply an inherent of available precision in the necessary paleobiological studies that classify the proposed UA and its descendency.

As of the publish date of this comic, all of the college basketball teams mentioned (except the University of Virginia) were ranked in the top 25 of the {{w|AP Poll|Associated Press poll}}. The University of Virginia was the winner of the 2019 college basketball tournament, so that may have been why they were mentioned.

{| class="wikitable"
!Team name
!University
!Ranking
!Notes
|-
|Dayton
|{{w|University of Dayton}}
|#5
|A private Roman Catholic research university in Dayton, Ohio. Dayton has appeared in 18 tournaments, most recently in 2017.
|-
|Duke
|{{w|Duke University}}
|#6
|A private research university in Durham, North Carolina. Duke has appeared in 43 tournaments (most recently in 2019), and has won 5 national championships (most recently in 2015).
|-
|FSU
|{{w|Florida State University}}
|#8
|A public research university in Tallahassee, Florida. Florida State has appeared in 17 tournaments, most recently in 2019.
|-
|Gonzaga
|{{w|Gonzaga University}}
|#2
|A private Roman Catholic university in Spokane, Washington. Gonzaga has appeared in 22 tournaments, most recently in 2019.
|-
|Kansas
|{{w|University of Kansas}}
|#3
|A public research university with its main campus in Lawrence, Kansas. Kansas has appeared in 48 tournaments (most recently in 2019), and has won 3 national championships (most recently in 2008).
|-
|Louisville
|{{w|University of Louisville}}
|#11
|A public research university in Louisville, Kentucky. Louisville has appeared in 39<ref group="note" name="Louisville">Louisville vacated its tournament results from 2011-15, including its 2013 national championship, due to NCAA violations.</ref> tournaments (most recently in 2019), and has won 2<ref group="note" name="Louisville" /> national championships (most recently in 1986).
|-
|UVA
|{{w|University of Virginia}}
|Unranked
|A public research university in Charlottesville, Virginia. Virginia has appeared in 23 tournaments (most recently in 2019), and has won 1 national championship, in 2019.
|}

==Transcript==

:[A circular phylogenetic tree is shown, with various parts of the tree colored red, green, blue, and black. Text is written on the root of the tree and the first few branches, getting smaller until it becomes unreadable. The visible text is:]
:Duke
:Duke Gonzaga
:Louisville Duke UVA FSU
:Dayton UVA Kansas FSU

:[Caption below the panel:]
:I was kicked off the biology project after I secretly replaced all the phylogenetic trees in our new paper with March Madness brackets.

==Notes==
<references group="note" />

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Tournament bracket]]
[[Category: Basketball]]
[[Category: Biology]]