The Zedonk Problem

Discovery

BBC

Science, Technology

4.3 • 1.2K Ratings

🗓️ 30 November 2020

⏱️ 28 minutes

🔗️ Recording | iTunes | RSS

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Summary

Today I learnt that tigons and ligers are what you get when lions and tigers interbreed?!’ surprised listener Jamz G tells the doctors. ‘What determines whether species can interbreed?’ Geneticist Aoife McLysaght studies molecular evolution. She explains the modern definition of a species, built on ideas from Aristotle, Linnaeus and Darwin: a species is a group of organisms capable of interbreeding to produce fertile offspring. Hybrids – such as ligons and tigers – are usually infertile, because their common ancestors long ago diverged into the lions and tigers we know today. However, this definition isn’t absolute, and there are many ways a new species can be formed. Hybrids also offer rich study subjects for scientists. Mathematical biologist Kit Yates discusses why he’s been reading research papers about hebras and zorses (horse x zebra) as their patterns offer insights into how cells spread and develop into organisms, building on a prediction made by codebreaking mathematician Alan Turing. And it turns out that these hybrids are even more intriguing. As speciation and evolution expert Joana Meier explains, hybrids are not always infertile. Hybridisation can lead to successful new species arising, such as in Lake Victoria’s cichlid fish, who it seems have been having a wild evolutionary party for the last 15,000 years. And the picture gets even murkier when we discover that modern genetics reveals our human ancestors successfully mated with Neanderthals. Presenters: Hannah Fry & Adam Rutherford Producer: Jen Whyntie

Transcript

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0:38.0	Hello and welcome to the curious cases of Rutherford and Fry on Discovery for the BBC. This is the program where you send us in the queries, questions and conundrums that you are curious about and we will look into
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0:49.8	cases at BBC.co. UK and on with the show.
0:57.0	A menagerie of crossbreeds and a bag of strange names for this curious case sent in by James G on Twitter
1:06.8	He wrote to us with today's question
1:09.2	Today I learned that TIGON's and LIGAS are what you get when lions and tigers
1:13.9	into breed. So what determines where the species can interbreed and why aren't
1:19.5	lIGAS and TIGON's the same? Okay well given that you are our resident geneticist Adam, I'd say this one sounds
1:25.8	like it's quite up your street.
1:27.8	So go on then, Smoshy Pants, what is the difference between a TIGON and a LIGA.
1:33.0	Well, that sounds like the beginning of a really bad joke,
1:35.0	but a LIGA is the offspring of a male lion with a female tiger,
1:40.0	and a TIGON is the other way round.
1:42.0	And they're different? Yes, they are. Can you tell the difference? No I can't. They both look like big scary cats.
1:47.2	If I showed you a picture of both of them would you ever tell which was which?
	...

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