Faux phylogenies II

It is possible to produce a phylogeny of any group of objects that vary in their intrinsic characteristics, and where those characteristics can be inferred to vary through time. I have previously reported some examples of a Tree of LIfe where "life" has been interpreted very broadly, to include legendary figures, cartoon animals, pokémon, and dragons (see Faux phylogenies). Here, I broaden the scope even further.

Phylogeny of taste

This first example comes from the July-August 1998 edition of the Annals of Improbable Research (vol. 4, no. 4), in which Joe Staton published an article entitled Tastes like chicken? It contains the following tetrapod phylogeny onto which has been mapped what they taste like. Note that Homo sapiens is included.

Phylogeny of breakfast

Following the taste theme, Nash Turley works on community phylogenetics, and this has lead him to contemplate the phylogenetics of his own breakfast. This vegetarian feast contains 15 species in 11 families.

Insect blog phylogenetics

Moving on to cultural evolution, Morgan Jackson has investigated how insect blogs are related to each other. His phylogenetic analysis of entomology blogs was based on blog morphology, physiology, geography, ecology and behaviour. It produced the following tree, onto which has been plotted the insect families concerned.

Evolution blog phylogenetics

In a similar vein, when the blogger known as Psi Wavefunction hosted the 20th Carnival of Evolution, this was summarized as a phylogenetic tree. The tree was produced by the simple expedient of aligning the URL addresses of the Carnival submissions and performing a parsimony analysis, based on treating the letters as amino acid codes. I can't believe that it worked.

Android bubble shooter games

Finally, Megafouna Software has produced a phylogeny of Android bubble shooter games, based on a small set of their features.

Albert Einstein's consanguineous marriage

In previous blog posts, I have mentioned several well-known people who were involved in consanguineous marriages, which is defined as the union of two people who are related as closer than second cousins. In the first post (Charles Darwin's family pedigree network) I discussed in detail Charles Darwin (who married his first cousin); and in a later post (Toulouse-Lautrec: family trees and networks) I discussed the artist Henri Toulouse-Lautrec, who was the offspring of a marriage between first cousins. Now, it is the turn of Albert Einstein (1879-1955).

Einstein's first marriage (in 1903) was to a former fellow physics student, Mileva Marić (1875-1948). They had three children: Lieserl (1902-?), who was born the year before they married, Hans Albert (1904-1973) and Eduard (1910-1965). Einstein seems to have been far from the ideal husband or father, as detailed in the book by Roger Highfield & Paul Carter (The Private Lives of Albert Einstein, St. Martin's Griffin, 1994). Some brief information is given below.

When the marriage ended, Einstein married (in 1919) Elsa Löwenthal (née Einstein) (1876-1936), who brought with her two daughters from her own first marriage: Ilse (1897-1934) and Margot (1899-1986). As shown in the family pedigree below, Albert and Elsa were first cousins through their mothers (traced in red) and second cousins through their fathers (traced in blue). [NB. This is only part of the family tree.]

The main issue here is that this pedigree is a reticulating hybridization network, rather than a diverging tree, which clearly shows the problems with consanguineous marriages. The genetic diversity of any individual born from such a marriage has a much higher risk of expressing recessive genes in their phenotype, many of which cause serious health problems. For example, several of Darwin's children died young, and several others were apparently infertile. As well, Toulouse-Lautrec is well-known for his short stature and genetic deformities, and his brother died young, and several of his cousins (also the offspring of a consanguineous marriage) had the same genetic problem's as himself. Consanguineous marriages are not encouraged, if children are an intended outcome (see Bennett et al. 2002. Genetic counseling and screening of consanguineous couples and their offspring: recommendations of the National Society of Genetic Counselors. Journal of Genetic Counseling 11: 97-119).

Elsa and Albert are not known to have had any children (but see the note below), and it has been assumed that they had a relatively platonic relationship. So, this particular story does not have the same sad ending as those of Darwin and Toulouse-Lautrec. It would be interesting to know whether Albert and Elsa's childless state was a deliberate decision (in light of the possible genetic problems for any child), a consequence of age (they were in their 40s when they married, which makes pregnancy risky), or a result of (unreported) miscarriages.

The following note about Einstein as a husband is from The other side of Albert Einstein:

Einstein was far from the ideal husband. A year before they married, Maric gave birth to a daughter, Lieserl, while Einstein was away. The child's fate is unknown – she is presumed to have been given up for adoption, perhaps under pressure from Einstein, who is thought to have never seen his first born. After the marriage, Mileva bore two sons but the family was not to stay together. Einstein began an affair with his cousin Elsa Löwenthal while on a trip to Berlin in 1912, leaving Mileva and his family two years later. Einstein and Mileva finally divorced in 1919 ... Einstein married Elsa soon after the divorce [he had been living with Elsa for nearly five years], but a few years later began an affair with Betty Neumann, the niece of a friend. By one account, Elsa allowed Einstein to carry on with this affair to prevent him sneaking around. That relationship ended in 1924, but Einstein continued to have liaisons with other women until well after Elsa's death in 1936.

For information about a possible child of Albert and Elsa in 1932, see Einstein's son? It's a question of relativity.

Composers and consanguinity

There are many other people whose names are well-known and who were involved in a consanguineous marriage. Notably, there have been several composers of classical music:

• Johann Sebastian Bach married his second cousin, Maria Barbara Bach. The pair had seven children together, but only four survived to adulthood.
• Edvard Grieg married his first cousin, Nina Hagerup. Their only child, a daughter, died at the age of one. Around the same time Nina also had a miscarriage.
• Sergei Rachmaninoff married his first cousin, Natalya Satina. They had two daughters who survived to adulthood.
• Igor Stravinsky married his first cousin, Yekaterina Nossenko. They had four children surviving to adulthood – two sons and two daughters.

Note that this type of marriage was very unusual for Rachmaninoff and Stravinsky, because the Russian Orthodox Church explicitly forbids marriage between first cousins (both couples needed to get permission from the Czar), and so the families involved also opposed their marriages. Apparently, the relevant families also opposed Grieg's marriage. Indeed, it is reported that Edvard and Nina were surprised and disappointed to find out that they were not able to have children together.

Toulouse-Lautrec: family trees and networks

In a previous blog post (Charles Darwin's family pedigree network), I mentioned several well-known people who were involved in a consanguineous marriage, which is defined as the union of two people who are related as closer than second cousins. In that post I discussed in detail Charles Darwin (who married his first cousin); and in this post I discuss the artist Henri Toulouse-Lautrec, who was the offspring of a marriage between first cousins.

I thought that this would be a simple post, because there must be people who have studied the Toulouse-Lautrec-Montfa genealogy, given Henri's fame as a Post-Impressionist artist, along with the widespread knowledge that his phyiscal disabilities were genetic. But it turned out not to be so — there is no broad family tree that I could find, and no detailed discussion of inbreeding. The main information easily available is the direct lineage of inheritance of the various noble titles to which Henri would have been heir (had he survived his father, the Comte de Toulouse-Lautrec-Montfa), which can be traced back for more than 1000 years (see Vizegrafschaft Lautrec). However, the main interest for biology lies in his genetic relationship with his cousins, as we shall see below.

So, I sat down for a day to compile the family history for myself. The resulting genealogy is incomplete, but all of the relevant people are in it. I could not find all of the details about some of these people, either, which are apparently not available on the web; and some of the actual dates are inconsistent across different sources. In general, I have followed Dupic (2012).

When genealogical trees become networks

The point of this post is that marriages within a family turn the family tree into a network. So, a pedigree can be tree-like or not. In the latter case it is an example of a hybridization network.

This first genealogy shows a standard family tree for a single individual, looking backward in time from the bottom. So, this person is #1, the parents are #2 (father) and #3 (mother), and so on back through the generations, always with the male parent on the left (as is the convention). This example covers six generations, showing that without inbreeding everyone has 32 great-great-great grand-parents. These 32 people's genes are mixed more-or-less randomly (depending on recombination and assortment) to produce person #1. This is a good thing, evolutionarily, because there is then genetic diversity within #1.

However, with inbreeding some part of the ancestry disappears (when looking backward in time), because another part of the ancestry is duplicated in its place (this is called "pedigree collapse").

The second genealogy shows what happens when person #7 is the daughter of someone else in the same pedigree. If she is the daughter of #10 and #11, for example, then #5 and #7 would be sisters, and #2 and #3 would be first cousins. Now, person #1 has only 24 great-great-great grand-parents, and some of them are contributing to their descendants twice, rather than once (ie. #40–#47). This means that the genetic diversity in person #1 is less than it would be without the inbreeding. More to the point, any recessive alleles that exist in the ancestry have an increased probability of being homozygous in #1, and thus being expressed in the phenotype.

Toulouse-Lautrec's ancestry

This is, unfortunately, exactly what happened to Henri Toulouse-Lautrec, whose pedigree network is shown in the next figure. It is complete for six generations, plus an important part of the seventh. It is difficult to be complete beyond this generation, as the information becomes sparse, particularly about the female family members.

As shown, Henri's parents were first cousins, because their mothers were sisters. In addition, his maternal grandfather (#6) also had recent inbreeding in his history, because his mother (#13) was the daughter of a first-cousin marriage. This is not nearly as much inbreeding as has been implied by most commentators about Henri's life, but it is enough to potentially create genetic problems.

Note that it was Henri's mother's side of the family that was involved in the recent inbreeding, but the de Toulouse-Lautrec Montfa side was prone to the same thing, as are most titled families. As noted above, Henri died before inheriting his title. The title Comte de Toulouse-Lautrec-Monfa passed to Alphonse' next brother, Charles (1840-1917), who had no children, and thence to the next brother, Odon (1842-1937), and finally to Odon's son, Robert (1887-1972), who also had no children. The Internet seems to be silent about what happened to it after that.

Consequences of inbreeding

For Henri, life was tragic because he ended up with two copies of one particular recessive allele. The medical profession has been interested in this ever since his death, and much information is therefore now available about his condition (eg. Albury & Weisz 2013; Leigh 2013).

Albury & Weisz (2013) note:

The condition from which he probably suffered was first described in 1954 by the French physician Robert Weissman-Netter. It was named pycnodysostosis in 1962 by Marateaux and Lamy and was soon attributed to this artist as the "Toulouse-Lautrec Syndrome" ... Pycnodysostosis is a hereditary autosomal recessive dysplasia caused by an enzyme deficiency, namely of cathepsin K (cysteine protease deficiency in osteoclasts), reducing the normal bone resorption and leaving an incomplete matrix decomposition ... Toulouse Lautrec had a short stature with shortened legs, a large head due to a lack of closure of the fontanellae (which he usually covered with a hat), a shortened mandible with an obtuse angle (covered with a thick beard), dental deformities that required several surgical interventions, a large tongue, thick lips, profuse salivation, and a sinus obstruction with post-nasal drip. With fractures of the long bones during childhood, later on of the clavicle, with progressive hearing problems and cranio-facial deformities, Lautrec’s condition would complete the diagnosis of pycnodysostosis.

It seems to be widely recognized that Henri threw himself into his art at least partly to compensate for the psychological damage produced by his physical condition (he also became an alcoholic). As Leigh (2013) notes, his mother's side of the family had money (his father's side had a title but little money), and so Henri was financially free to do what he liked. He worked at a prodigious rate, and produced a life-time's worth of art in just 15 years — perhaps most famously his flamboyant lithograph posters (still as popular today as they were in his own time), but also oil paintings, watercolours, sculptures, ceramics and stained glass. He died at his mother's Château Malromé at age 36, after a stroke, but ultimately probably from tuberculosis (Albury & Weisz 2013).

Further inbreeding in the family

I noted in my previous post about Charles Darwin that, not only did he marry his cousin, his own sister married his wife's brother, thus literally keeping things in the family. In Henri Toulouse-Lautrec's case, the same thing happened: his paternal aunt married his maternal uncle, as shown in the next figure. This pedigree shows some more information about Henri's closest relatives, emphasizing the pair of consanguineous marriages.

There are 14 people shown in Henri's generation, all born to first-cousin marriages. (There may have been two more children in the Alix–Amédée marriage, but I have been unable to find any direct reference to them.) Of these people, six seem to have had disabilities similar to Henri's: Henri himself; his brother, who died the day before his first birthday; Madeleine, who died as a teenager; Geneviève; Béatrix; and Fides. The latter was so small that apparently she lived her entire life in a baby carriage (Rosenhek 2009). The photo below shows Henri with most of the Tapié de Céleyran family. It was taken in the summer of 1896 at Château du Bosc, where Henri had been born.

The two elderly women in the middle are Gabrielle (left) and Louise (right), the maternal and paternal grandmothers (they were sisters, remember). The father, Amédée, is at the rear centre (sticking his tongue out at the photographer), and the mother, Alix, is standing at the far right. Standing next to her is the oldest son, Raoul; and his wife, Elisabeth, is seated at the far left. The next two sons, Gabriel and Odon, are absent, along with their wives. The next son, Emmanuel, is standing at the back left; and his wife, Marie-Thérèse, is seated next to the pram (middle right). The youngest sons are sitting on the ground at the front centre, with Alexis on the left and Olivier on the right. The first-born daughter, Madeleine, was already dead when the photo was taken. The next three daughters are sitting at the middle left, with Germaine sitting on Elisabeth's lap, Geneviève in front of her, and then Marie seated on the ground. Béatrix is at the middle right, sitting next to Marie-Thérèse, and Fides is in her pram. Henri himself is seated on the ground at the far left. His brother, Richard, had also died before the photo was taken. The remaining four people (standing either side of Amédée) are other relatives.

Nevertheless, this large family did manage to survive the effects of inbreeding, unlike Henri's own family. At least seven of the children survived to have children of their own (~19 grand-children):

Person Raoul Gabriel Odon Emmanuel Germaine Marie Alexis

Spouse Elisabeth DAUDÉ de LAVALETTE (1870-1956) Anne de TOULOUSE-LAUTREC (1873-1944) Marguerite TAILLEFER de LAPORTALIÈRE (1878-1958) Marie-Thérèse des CORDES Alexandre d'ANSELME (1876-1912) Adrien de RODAT d'OLEMPS (1806-1884) Anne Marie de MALVIN de MONTAZET (1885-1974)

4 children 3 children 1 child 2 children 2 children 3 children 4 children

Note that Gabriel and Anne were third cousins, since they had great-grand-fathers who were brothers; nevertheless, they had 3 female children, at least one of whom also had 3 children. One of Alexis' sons (ie. Henri's second cousin once removed) was well-known art critic Michel Tapié de Céleyran (1909-1987), who married and had seven children, two of whom died in infancy.

Inbreeding increases the probability that recessive alleles will be expressed, but it does not make this inevitable. In Henri's case, two disabled children in succession seems to have dissuaded his parents, and they separated, whereas his aunt and uncle had a healthy child the second time, and so they continued producing a family. However, these days it is not recommended that you marry any of your first cousins.

Conclusion

Evolution is about biodiversity at all hierarchical levels, not just between or within species, but within individuals as well. Average intra-individual genetic diversity reaches a maximum when the ancestry is tree-like, and reduces with each instance of inbreeding, which turns the tree into a network of increasingly greater complexity.

I have discussed an even more extreme example of consanguinity in a previous post (Family trees, pedigrees and hybridization networks), in which the inbreeding became so severe that the royal family lineage actually came to an end.

References

Albury WR, Weisz GM (2013) Toulouse-Lautrec and medicine: a triumph over infirmity. Hektoen International 5: 3.

Dupic S. (2012) Toulouse-Lautrec - Généalogie 87 le site de référence de la généalogie de la haute-vienne.

Leigh FW (2013) Henri Marie Raymond de Toulouse-Lautrec-Montfa (1864-1901): artistic genius and medical curiosity. Journal of Medical Biography 21: 19-25.

Rosenhek J (2009) Picture imperfect: tiny Henri de Toulouse-Lautrec’s talent – and troubles – were larger than life. Doctor's Review Oct 2009.

Charles Darwin's family pedigree network

It is widely known that Charles Darwin was married to his first cousin Emma Wedgwood. Emma came with a substantial dowery, being the grand-daughter of Josiah Wedgwood, the founder of the Wedgwood pottery firm (as, indeed, was Darwin himself, via his mother). Darwin already had a substantial allowance from his own father (a successful physician, real estate speculator, investor, and money lender), and the combined incomes allowed him to live the life of a "gentleman of independent means". He thus conducted his scientific work unhindered by the practical concerns of the rest of us.

What is perhaps less well known is that Darwin was interested in (and concerned about) the genetic effect on his children of his consanguineous marriage. He performed many experiments on inbreeding in plants, and demonstrated that the offspring of cross-fertilized plants were more vigorous and numerous than the offspring of self-fertilized plants. It occurred to him that the same thing might be true for animals, as well, including humans.

Furthermore, he thought that this might be an explanation for the unhealthy nature of his own children. Three of his ten children died young, and three more of them had long-term marriages that produced no offspring (implying infertility). These data stand out even within the Darwin-Wedgwood families, let alone outside it.

In birth order, the children were:
William Erasmus – married, no children
Anne Elizabeth – died young (tuberculosis)
Mary Eleanor – died young
Henrietta Emma – married, no children
George Howard – married, four children
Elizabeth – unmarried, no children (apparently had difficulties with words and pronunciation)
Francis – married twice, two children
Leonard – married twice, no children
Horace – married, three children
Charles Waring – died young

Part of the Darwin / Wedgwood pedigree is shown in the figure, which is taken from the 2010 paper by Tim M. Berra, Gonzalo Alvarez and Francisco C. Ceballos (Was the Darwin / Wedgwood dynasty adversely affected by consanguinity? BioScience 60: 376-383). Note that the family tree is drawn as a hybridization network (also called a "path diagram"), rather than a traditional family tree, which is an important point that I have previously emphasized for pedigrees (Family trees, pedigrees and hybridization networks).

The diagram shows only four of the people from Darwin's children's generation (including only one of his own children), but all four of these people (and their unshown siblings) are the offspring of first-cousin marriages. Indeed, Louisa Frances Wedgwood's parents were double first cousins (ie. they were cousins via both of their parents). These consanguineous marriages all involved the children of Josiah Wedgwood II (they are four of his eight children who survived to adulthood) — this is not a family tradition that should be encouraged. (You will note that Darwin's sister Caroline married Emma's brother Josiah III, thus literally keeping everything in the family.)

The inbreeding coefficient (the probability that at a given locus an individual receives two identical genes as a result of common ancestry) of Louisa Frances is 0.126, while that of the other three people is 0.063. Most of the other people in the Darwin / Wedgwood family have inbreeding coefficients of 0.000. Berra and his coauthors compared the child mortality with the inbreeding coefficients for four generations of the family, and concluded that there is a statistically significant relationship.

The data look like this for the 20 marriages in the final three generations:
                         Child mortality to 10 years
                                 =0     >0
Inbreeding coefficient =0        11      5
                       >0         1      3
Clearly, the second sample size is rather small, but the unconditional test of two independent proportions yields p=0.076. The relative risk is 2.4 (ie. the children of first-cousin marriages were >2 times more likely to die before 10 years of age than were the other children).

Darwin did not have easy access to these data, of course, but they justify his concern for the effect on humans of inbreeding. Indeed, he went so far as to suggest that the 1871 British census should enquire about consanguineous marriages ("the returns would show whether married cousins have in their households on the night of the census as many children as have parents who are not related; and should the number prove fewer, we might safely infer either lessened fertility in the parents, or which is more probable, lessened vitality in the offspring"). This suggestion was not implemented.

However, his son George (the oldest fertile child) did persue the matter of inbreeding. Indeed, he introduced the idea of using the frequency of occurrence of the same (birth) surname among married couples as a means to study the level of inbreeding in a population. Such surname models are still used in human population biology today.

Henri de Toulouse-Lautrec
1864-1901

Incidentally, many other famous people have married their first cousin, although unlike Darwin they did not necessarily have any children with them. For example, Albert Einstein married Elsa Löwenthal (née Einstein), his first cousin through their mothers and second cousin through their fathers; however, his three children were from his relationship with his first wife, Mileva Marić. H.G. Wells' first marriage was to Isabel Wells, a first cousin, but his four children were with his second wife and two of his lovers. Edgar Allan Poe's only marriage was to his cousin Virginia Clemm, but they had no children. [See the later post: Albert Einstein's consanguineous marriage]

Sadly, there are also well-known cases where the offspring of first cousins seem to have suffered badly. Perhaps the best known of these is the artist Henri de Toulouse-Lautrec. Henri's two grandmothers were sisters, so that his parents were first cousins, and he suffered from congenital health conditions that are usually attributed to genetic disorders. For example, Henri fractured his right thigh bone when he was 13 and his left at 14, and the breaks did not heal properly. His legs ceased to grow, so that he achieved the shape for which he is best known, with an adult-sized torso but child-sized legs. He died at the young age of 36. [See the later post Toulouse-Lautrec: family trees and networks]

First-cousin marriages have declined significantly since Darwin's time. According to Adam Kuper (2010. Incest and Influence: the Private Life of Bourgeois England. Harvard University Press), cousin marriages have declined from 1:25 marriages (among the upper middle classes) in the 19th century to 1:6,000 in the 1930s and 1:25,000 in the 1960s. Kuper's book provides an interesting insight into why such marriages were previously so common among the upper bourgeoisie and why they are much rarer now.

First-degree relationships and partly directed networks

I have noted before that a pedigree is a network not a tree, and specifically it is a hybridization network (Family trees, pedigrees and hybridization networks). That is, in sexually reproducing species, every offspring is the hybrid of two parents. If we include both parents in the pedigree, plus all of their relatives, then this will form a complex network every time inbreeding occurs.

This situation can be generalized to groups of closely related individuals, such as cultivated plants and domesticated animals, where human-mediated inbreeding has resulted in the formation of new breeds and cultivars with limited genetic diversity. In the extreme case, the network will consist of first-degree relationships, where the branches connect parent-offspring relationships or sibling relationships.

An example of this is provided by the work on the genetics of grape cultivars by Myles et al. (Myles S, Boyko AR, Owens CL, Brown PJ, Grassi F, Aradhya MK, Prins B, Reynolds A, Chia JM, Ware D, Bustamante CD, Buckler ES. 2011. Genetic structure and domestication history of the grape. Proceedings of the National Academy of Sciences of the USA 108: 3530-3535).

The genotype data were generated from a custom microarray, which assayed 5,387 SNPs genotyped in 583 unique Vitis vinifera samples from the US Department of Agriculture (USDA) germplasm collection. Estimates of identity-by-descent (IBD) were calculated based on linkage analysis for all pairwise comparisons of samples. These IBD values were calibrated based on known pedigree relationships (ie. confirmed parent-offspring relationships), and this was used to differentiate between parent-offspring and other pedigree relationships. For each cultivar that was related to at least two other cultivars by an estimated parent-offspring relationship, the proportion of SNPs consistent with Mendelian inheritance was used to determine the two parents.

The authors found that 75% of the grape cultivars were related to at least one other cultivar by a first-degree relationship. The first figure (above) shows the frequency histogram of these first-degree relationships, along with the resulting complex pedigree structure, which can be visualized as a set of undirected networks. This set is dominated by a single network with 58% of the cultivars, each related to at least one other cultivar by a first-degree realtionship.

Fig. 3. Network of first-degree relationships among common grape cultivars.
Solid edges represent likely parent-offspring relationships. Dotted edges represent sibling
relationships or equivalent. Arrows point from parents to offspring for the inferred triplets.

The authors inferred that about half of the first-degree relationships were likely to be parent-offspring, with the other half being labeled "sibling or equivalent" (because complex crossing schemes can generate IBD values that are indistinguishable from sibling relationships). By evaluating Mendelian inconsistencies, they assigned parentage for 83 triplets of cultivars. The second figure shows a directed hybridization network of some well-known grape cultivars that includes several resolved triplets.

Note that the hybridization network is only partly directed — quite a few of the edges do not have a uniquely identified direction, based on the SNP data. This is an issue that I have not seen directly addressed in the literature. Practitioners tend to treat phylogenetic networks (and trees) as either directed or undirected, rather than a mixture of both, as this characteristic is determined by the presence or absence of a root node. However, in the grape case there is no root identifiable based on the cultivar SNP data. (There is a scenario for the origin of modern grape cultivars from Vitis sylvestris around the eastern Mediterranean, but even this is complicated by hypothesized later gene flow between V. sylvestris and V. vinifera.)

Perhaps the possibility of partly directed phylogenetic networks needs more consideration.

Faux phylogenies

It is, of course, possible to produce a phylogeny of any group of objects that vary in their intrinsic characteristics, and where those characteristics can be inferred to vary through time. One popular subject is the Tree of Life, but where "life" is defined in rather a loose fashion. Here are a few examples of what I mean.

Note: there is a follow-up post (Faux phylogenies II), as well.

Legendary figures

This first one is reproduced from pages 90-91 of Bart Simpson's Guide to Life (1993, Harper Collins). It includes a series of somewhat legendary figures; and newts apparently evolved twice.

Bart Simpson's Tree of Life
© Matt Groening

Cartoon animals

Mike Keesey, from the Three-Pound Monkey Brain blog, has an example of his own, in which he took a stab at a phylogeny of cartoon animals (it is the third phylogeny on that blog page, or click the image below).

Mike Keesey's
phylogeny of cartoon animals

Kalle Anka

In 1993, the cartoonist Don Rosa produced a genealogy of Donald Duck and his family, intended to resolve decades of contradictions among the comic-book stories.

Don Rosa's Donald Duck genealogy
characters © Disney

There are many other versions of this genealogy, most of which are linked at this page. The first one on that page is the most detailed and complete version of the family tree.

Monstrasinu

The July-August 2012 edition of the Annals of Improbable Research (vol. 18, no. 4, pp. 15-17) contained an article by Matan Shelomi, Andrew Richards, Ivana Li and Yukinari Okido called "A phylogeny and evolutionary history of the Pokémon". Below is a low-resolution image, but a much higher resolution version of the phylogeny (2.9 MB) can be found here.

Pokémon phylogeny
characters © Nintendo

Asian lóng and Eurasian dragons

At the same time, Rob Colautti produced a t-shirt design from his phylogeny of dragon-like organisms, which is based on a neighbor-joining analysis of 27 distinct traits for 76 pieces of historical artwork.

Rob Colautti's dragon phylogeny

According to his Facebook page, he is intending to publish this phylogenetic analysis in the afore-mentioned Annals of Improbable Research, and to make the dataset available online, as well.

Family trees, pedigrees and hybridization networks

A family tree is technically called a pedigree. This is because it is not really a tree. Branches do not fuse in a tree, whereas in a pedigree every individual is the fusion of two genealogical branches. That is, in sexually reproducing species, every offspring is the hybrid of two parents. A family tree is only a tree if you trace one pair of ancestors through their descendants while ignoring the spouses.

So, a pedigree is a network not a tree, and specifically it is a hybridization network. This can be seen most clearly when there is a considerable level of inbreeding going on. Under these circumstances, both spouses are likely to be offspring of the same ancestors in the not-too-distant past, and so they will both be connected by the network branches. We are all of us connected in the human pedigree network, of course, but for most of us our (shared) common ancestor is a long way back in the past.

A high degree of inbreeding is common in many human cultures, but it is particularly prevalent among royalty, even in cultures with relatively little inbreeding among the common populace. I will illustrate this phenomenon with what is often considered to be the most extreme example recorded — the inbreeding that lead to the demise of the Spanish branch of the Habsburg dynasty in 1700 (other branches of the House of Austria continued until 1780).

The Spanish branch of the Habsburgs were kings of Spain from 1516 to 1700. Under Habsburg rule, Spain reached the peak of its power in Europe (covering Spain, the Netherlands and parts of Italy), and the world-wide Spanish Empire reached its greatest extent. The last king of this dynasty was Charles II, who was the product of such serious inbreeding that he was disfigured, physically disabled and mentally retarded (see Alvarez et al. 2009 for a full description). The fact that he had no children lead to the War of the Spanish Succession, although this was mostly precipitated by the reaction of the reigning French king, Louis XIV.

Click to enlarge.

The basic issue here is that the Spanish Habsburgs tried to keep power by literally "keeping it in the family". During the last three-quarters of their time, from 1551 to 1700, no outsider married into the Spanish royal family. Indeed, if one looks at the six kings from 1497 (when Philip the Fair married Joanna I of Castile and Aragon, and thus became Philip I), then we note that there were 11 marriages, most of which were among blood relatives — two uncle-niece marriages, one double first cousin marriage, one first cousin marriage, two first cousins once removed marriages, one second cousin marriage, and two third cousin marriages. (See Wikipedia for an explanation of these relationship terms.) This gave Charles II an inbreeding coefficient of 0.254 (calculated by Alvarez et al. 2009) — for comparison, the offspring of a brother-sister union would have a value of 0.250, as would the offspring of a parent-child union. Phillip III (Charles II's grandfather) also reached a high level: 0.218. Both of these people were the offspring of uncle-niece marriages.

This first diagram (linked from Wikipedia) shows the pedigree of Charles II, the final member of the dynasty. It illustrates the above points in the usual manner for a family tree. It shows only the royal lineage, as there were many other offspring, and indeed other marriages (Philip II married four times, Philip IV twice, and Charles II also twice). However, none of the male offspring were alive at the time of the death of Charles II, and nor were most of the females. Another of the consequences of the inbreeding was a poor survival rate among the children.

My point with this blog post is that the family tree can also be drawn as a network, as shown in the second diagram (which is also called a "path diagram" by geneticists). This illustrates the same pedigree as above, but with a few additions (at the left) to illustrate the lineage to Don Carlos (crown prince Charles), another highly inbred male (coefficient 0.211), being the offspring of double first cousins. This form of the diagram makes the connection between a family tree and a hybridization network clear — they are both ways of drawing a pedigree.

Basically, the two diagrams illustrate the same point — the Habsburg's defeated their own purpose, because they ultimately lost power by refusing to share it with anyone else. Biology is about biodiversity, and conserving biodiversity applies within your own family just as much as anywhere else.

Note
There are several follow-up posts on this topic, about other famous people:
Charles Darwin's family pedigree network
Toulouse-Lautrec: family trees and networks
Albert Einstein's consanguineous marriage

Further reading

Alvarez G., Ceballos F.C., Quinteiro C. (2009) The role of inbreeding in the extinction of a European royal dynasty. PLoS ONE 4: e5147.

If you know little about the pros and cons of inbreeding, then this blog post will enlighten you:
Why inbreeding really isn’t as bad as you think it is.