Liliger bred in Siberian zoo

September 18, 2012 • 3:59 am

You’ll possibly know of ligers from the movie “Napoleon Dynamite” (2004), in which a lad was obsessed with drawing them. Ligers are hybrid offspring from the cross of a male lion and a female tiger (the offspring of the reciprocal cross is called a “tiglon“). But you probably haven’t heard of—or seen—a liliger, which is the offspring of a hybrid female liger and a male lion. In genetic parlance, it’s the offspring of a hybrid backcross.

They breed the female hybrids because male ligers are sterile, conforming to Haldane’s Rule, named after geneticist J. B. S. Haldane, who first noticed this regularity. (H’s Rule is the generalization that if you hybridize two species and only one of the two sexes of offspring is sterile or inviable, that sex will almost invariably be the one having unlike sex chromosomes, or “heterogametic”.  In mammals and my fruit flies, the hybrid males are XY  [females xx] and thus are the susceptible sex, but in birds and butterflies it is the females who have unlike sex chromosomes and thus liable to be sterile or inviable as hybrids. I spent a lot of my career working on the genetic and evolutionary basis of Haldane’s Rule.)

According to the BBC News Europe, where you can find a short video (I can’t embed it), the liliger, named Kiara, has been adopted by the zoo’s resident cat because the mother can’t provide enough milk. That itself may be a deleterious symptom of hybridization.  Although the film clip mentions criticisms of breeding such hybrids, saying they are of no conservational value and take up zoo space, I think they are of genetic and evolutionary value, for they tell us how well the genes of tigers and lions can cooperate in producing an offspring, and what maladaptive symptoms might arise from that hybridization.  The data on hybrids between mammals, particularly ones as distantly related as lions and tigers, are still scant.

Here’s a screenshot from the video:

BTW, the common ancestor of lions and tigers lived about 3.7 million years ago.  You can get this kind of information from the wonderful site TimeTree, where you can plug in any two species (including humans) and find out when their common ancestor lived, as well as the data used to determine that time. Your common ancestor with cats, for example, lived about 94.4 million years ago.

h/t: Geoff

26 thoughts on “Liliger bred in Siberian zoo

  1. How long is one small moggie going to be able to feed a liliiger cub? Interesting though, it looks pretty much like a lion to me.

    1. Just what I was thinking – a gigantic female liger can’t produce enough milk, but an average kitteh can? Perhaps that is attributable to a genetic incompatibility, though it could just be something about the zoo environment.

  2. I didn’t notice this the first time I saw this video, but the mother cat has one of her own kittens to the left of her. Enough milk to go around?

      1. Humans and bonobos/chimps have a common ancestor about 7 megayears back, rather than a bit under 4 megayears. So, presumably such a cross would be even more difficult… but likely not impossible.

        On the other hand, you definitely need a mad scientist. There’s the obvious fundamental ethically problematic nature of creating human/pan chimera even by hybridization. But also, Bonobos and common chimps are both endangered species, so it would be irresponsible to use a female chimp’s ova and have her gestate. On the other hand, both types are substantially stronger than humans, which might carry over to a hybrid, risking a human host mother.

        So, assuming our hypothetical mad scientist has some ecological concerns (say, is interested in hybridization as at least partial means to his preferred end of protecting Pan against extinction), the most efficient mad science approach would appear to be some initial work in vitro. Use a large number (say, 100 or so) of harvested human ova, attempt fertilization with sperm harvested from a couple male chimps on the side from a more conventional Pan breeding program, see what fraction get to the basic couple-dozen cell embryo stage, compare the result to pure human-human in vitro data. This should give some bounds on how many crosses would need to be attempted before getting one able to gestate to live birth (and cross enough lines to give the religious right fits).

        Of course, 100 human ova will run on the order of a million bucks, plus maybe $100k per chimp male (guessing wildly), plus equipment costs and salary for an Igor research assistant to help take care of the chimps. Not cheap mad science, even before you get to hiring a host mother. Kidnapping is an option for a sufficiently mad scientist, but the risks may add to the effective costs. Heroic boyfriends tracking down the hidden lab, forcing an expensive relocation, and that sort of thing. The usual contract rate for a host mother seems to be around $25k, but there’s probably going to need to be a premium for the NDA.

        It’s also possible the mad scientist is a Helen Narbon or that the research assistant is an Igorina, and thus on the books twice; either would save a bit. You’d still probably want multiple egg donors, I’d think, to insure any inability to cross is not just an individual infertility.

        1. But also, Bonobos and common chimps are both endangered species,

          And tigers aren’t?

          Why haven’t anyone tried cross chimps, bonobos and gorillas first?

          1. A good point.

            My understanding is that most ligers and tigons result as “accidents” rather than deliberate crosses.

            There have been crosses between bonobo and regular chimps, but they split more recently than from humans. Gorillas are thought to have split a couple megayears earlier than the humans, so a gorilla/chimp cross would strongly suggest a human cross would also be possible. However, the relatively anti-social nature of gorillas makes such an attempt unlikely.

      2. My very first anthro prof (circa 1970) told of a novel about said mad scientist who mated his wife with a chimp. I’ve periodically tried to identify the author and/or name of book without success.

        Does anyone know of it?

        1. No, but there’s a lot of short stories & books that are close

          I tripped over this one which is too recent, doesn’t have an impregnated woman, but does sound delightfully dark:- GOD’S GRACE By Bernard Malamud

          “…is the most up-front fable he has yet written, complete with a defensive Yahweh, an ironic Moses, Jesus, talking chimps and perverse gorillas, biblical rites of sacrifice, plus, of course, the pointed moral wisdom – this time full of dark prophecy. Does the darkness emerge from the author himself growing older, facing his own end, or his living in an age of crisis, when civilization is facing its own possible end? Whichever, there are in this novel moments of lucid beauty beside moments of harrowing blackness – Eden and Apocalypse between two covers”

          The main character is a Jewish anthropologist so I imagine the conversations he has with Yahweh will be entertaining if done right.

  3. That’s fascinating. I think it’s quite sad that the general public has a hard time seeing value in basic research — i.e., research with no immediate direct in-your-face medical or conservation applications. So I’m glad you point this out. Understanding the genetics of hybridization is a critical part of designing effective conservation and management strategies, in addition to the simple fact that these kinds of rare crosses add to our understanding of how evolution works.

    1. I would question the conservation value of understanding the effects of lion-tiger hybridization. Their original ranges hardly overlapped, and even then they probably used different habitats. So hybridization in the wild is hardly a major obstacle to their recovery.

      As for the scientific value, you’d think that breeding the pure species would trump experimental hybridization, unless the parents involved were somehow unsuitable for adding further to the gene pool (too inbred? But then the knowledge gained about hybrid incompatibility is of limited value).

  4. I’m in geophysics/meteorology, so my knowledge of the green slime coating the rocks and constantly mucking up the chemical composition of the atmosphere is limited, but I was surprised that our common ancestor with cats was so far back; I would have thought it would have been after the Cretaceous. Interesting that mammals were that diverse back then. Of course, my cats were surprised and embarrassed the link was that recent.

  5. Your common ancestor with cats, for example, lived about 94.4 million years ago.

    That 94.4 MYA number keeps coming up a lot — human v dog, human v cow, human v horse, human v dolphin.

    It’s a slightly younger number for the rodents, though: 92.4 MYA — but well within the margin of error.

    So…dare I ask? What was this Cretaceous-era common ancestor of the lot of us?

    Who’s our daddy?

    It can’t be the common ancestor of all mammals…the platypus line split with ours 167.4 MYA; the kangaroo, koala, and possum, 163.9 MYA.

    b&

        1. Regardless, there was some sort of ancestral form with a great deal of plasticity that gave rise to a very diverse group of lineages that all converge to not quite 100 MYA, with many of the splits occurring about the same time.

          I think it’d be really neat to know more about that ancestor.

          b&

          1. Look again the chart provided by Ant. You are talking about the common ancestor of Laurasiatheria and Euarchontoglires, which together include most of the modern mammal species.It’s a branching point like many others.

            1. What I see is that, with rounding, a hundred million years ago, there were a series of branchings over a few million years. Afrotheria and Xenarthra, then Xenarthra and Laurasiatheria, and then Laurasiatheria and Euarchontoglires.

              Before that, if I’m not mistraken, there was either a period of relative stability or the offshoots are missing. The older branches also seem to be relatively stable, whereas the branches from that 100 MYA split exhibit a great deal of diversity.

              Again, compare this with the recent discussion about living fossils; the ancestor of modern horseshoe crabs is unmistakably an horseshoe crab (even if it had more legs), and there hasn’t been any significantly different offshoots.

              But from that 100 MYA ancestor, we’ve gotten everything from sea otters to bats to us to elephants to possums

              And that’s why I’m wondering what that 100 MYA ancestor was like, and what made it so plastic.

              Or, of course, it could be that I’m not seeing enough of the picture….

              Cheers,

              b&

  6. Also, that TimeTree site is SCARY. It’s like they took all the reasons why strict molecular clocks are unrealistic and decided “F that S, let’s do it anyway!” and to hell with the fact that most of the dates are probably meaningless…

    1. I don’t think this comment is eithger fair or accurate; they’re not using strict molecular clocks and the dates are not meaningless. Rather than hash this out here, I’ll just forward you privately some comments I have from systematists on this issue. The TimeTree people have taken into account deviations from a “strict molecular clock” although you imply otherwise. I’ll just quote from one email by a very well known systematist, who will remain anonymous here:

      The TimeTree people have a book on their methods.  One can actually download the chapters freely.  In one chapter John Avise addresses the issue:
      http://www.timetree.org/pdf/Avise2009Chap02.pdf
      (see page 21)
      and in another Michael Benton, Philip Donoghue and Robert Asher discuss “Calibrating and Constraining Molecular Clocks”:
      http://www.timetree.org/pdf/Benton2009Chap04.pdf
      (see especially pages 41-44).

      My impression is that they are being careful, and they are also making use of fossils as well as worrying about rates of molecular evolution.  I don’t think it can be waved aside as using “a strict molecular clock”.

      I was worried about what you said because I use TimeTree as a teaching tool occasionally, and haven’t found it to be off very much. I’m reassured by what I’ve heard from systematists.

      1. Ah, now I see. I haven’t explored the site much, only formed an initial reaction from quickly reading through the site’s FAQs. Either the answers aren’t very informative, or, more likely, I was high on caffeine and granola when I was reading this morning. Either way, I’ll be more careful next time. After looking more thoroughly, and considering the comments you forwarded to me (all of whom are experts I hold in very high regard), I feel much better about the site and its applications. I think it is a good summary of the currently available literature — the underlying issue, of course, being the sometimes controversial methods used in the original literature. Something that came to me just now as I sit here writing this: I wonder how/if the site deals with uncertainty in age estimates. Or, more accurately I guess, how/if it expresses cases where the literature contains a wide range of date estimates for a particular group. From what I can tell, the site gives one single age for any particular divergence event, but in some cases, especially in frequently studied groups, there are many age estimates that may or may not be all similar. Just a thought. Like I said, haven’t explored much.

  7. Didn’t conservationsists ‘recreate’ the original wild horse, or at least shore up, the Przewalski’s horse through back-crossing of Hybrids?

    I also remember reading that Darwin speculated on backbreeding horses sometimes producing lightly stripped horses, which he assumed was more like the wild-type.

    So really how can anyone say this has nothing to do with animal conservationism, this is sorta-kinda-like the original panther, in a way.

Leave a Reply