We’re always taught that twins can either be identical or non-identical. But what is the basis for this? And is there ever a situation where twin type is not quite so binary?
Sources for this episode: 1) Davis, N., the Guardian (2019), Scientists stunned by discovery of ‘semi-identical’ twins (online) [Accessed 07/02/2021]. 2) Author unknown, BBC (2019), Semi-identical twins ‘identified for only the second time’ (online) [Accessed 07/02/2021]. 3) Author unknown, Wikipedia (date unknown), Twin (online) [Accessed 08/02/2021].
The term ‘Anthropocene’ (roughly translated as ‘Age of Man’) is a term that is sometimes thrown about on the radio or in science. But what is it exactly? As we’ll see today, the concept itself is relatively simpler, but nailing down the specifics is somewhat harder than it seems…
Sources for this episode: 1) Author unknown, Encyclopaedia Britannica (2020), Anthropocene Epoch (online) [Accessed 30/01/2021]. 2) Ashley, S., National Trust (date unknown), What is the Anthropocene? (online) [Accessed 30/01/2021]. 3) Author unknown, Wikipedia (date unknown), Chinese industralization (online) [Accessed 02/02/2021].
Science has to change with the evidence if it is to be trusted. One example of this comes with Dollo’s Law, named after the French Belgian biologist Louis Dollo. His original theory was that evolution would never, under any circumstances, retrace its path. However, as we’re going to see on the podcast today, that isn’t always the case. With new evidence came the need for a revamp of Dollo’s Law…
Sources for this episode: 1) Author unknown, Wikipedia (date unknown), Dollo’s Law of irreversibility (online) [Accessed 24/01/2021]. 2) Author unknown, Encyclopaedia Britannica (2018), Dollo’s Law (online) [Accessed 24/01/2021]. 3) Zimmer, C., National Geographic (2003), Recoil from Dollo’s Law (online) [Accessed 24/01/2021]. 4) The Editors, Encyclopaedia Britannica (2018), Peppered moth (online) [Accessed 27/01/2021]. NOTE: I think I get a bit mixed up in my speech at one point with the gastropod example. What I should have said is that shells started out coiled, uncoiled itself and then recoiled on at least two occasions.
In our third Rewind episode, I’m going to go back over the concept of dominant vs. recessive as a mechanism of genetic inheritance, which I’ve touched upon before but not really in any great detail.
Sources for this episode: 1) Fullick A., Locke, J. and Bircher, P. (2015), A Level Biology for OCR A. Oxford: Oxford University Press. 2) Thain, M., and Hickman, M. (2014), The Penguin Dictionary of Biology, 11th edition. London: Penguin Publishing Group. 3) Author unknown, Wikipedia (date unknown), Eye color (online) [Accessed 19/01/2021].
This episode is really going to do what it says on the tin- discuss the question of how many species there are in the world. This might seem a simple question, but a simple answer has eluded the scientific community for some years now. On the show today, I’m going to go through some of the methods past research has used to answer this question and what figures they came up with.
Sources for this episode: 1) Latty, T. and Lee, T., ‘Phys.org’ (2019), How many species on Earth? A simple question that’s hard to answer (online) [Accessed 16/01/2021]. 2) Mora, C., Tittensor, D. P., Adl, S., Simpson, A. G. B. and Worm, B. (2012), How Many Species Are There on Earth and in the Ocean? PLOS Biology 9(8): e1001127. A slight correction here- at one point I mention seven taxonomic levels, but I should have said six! The confusion came because ‘species’ was the seventh one.
Hi everyone, just a quick plug for my other show- After Alexander. This is a history podcast where we examine what happened between Alexander the Great’s death in 323 and the destruction of the last of the Hellenistic kingdoms by the Romans and Parthians. Specifically, it focuses on the Seleucid dynasty, descended from Seleucus I Nicator and eventually rulers over most of Alexander’s old empire in their glory days. If that sounds like it might be for you, feel free to head over and join us! Regular content resumes next week.
The Central Indo-Pacific (or CIP if you’re stuck for time) is a highly diverse region of the ocean. But how did it get to be this way? That’s what I’m going to be discussing, based on facts collated from the primary literature.
Sources for this episode: 1) Author unknown, Wikipedia (date unknown), Eocene (online) [Accessed 17/01/2021]. 2) Siqueira, A. C., Bellwood, D. R. and Cowman, P. F. (2019), Historical biogeography of herbivorous coral reef fishes: The formation of an Atlantic fauna. Journal of Biogeography: DOI: 10.25903/5cd265eb0a405. 3) Renema, W., Bellwood, D. R., Braga, J. C., Bromfield, K., Hall, R., Johnson, K. G., Lunt, P., Meyer, C. P., McMonagle, L. B., Morley, R. J., O’Dea, A., Todd, J. A., Wesselingh, F. P., Wilson, M. E. J. and Pandolfi, J. M. (2008), Hopping Hotspots: Global Shifts in Marine Biodiversity. Science (321): 654- 657. 4) Ivany, L. C., Patterson, W. P. and Lohmann, K. C. (2000), Cooler winters as a possible cause of mass extinctions at the Eocene/Oligocene boundary. Nature 407: 887- 890. 5) Author unknown, Wikipedia (date unknown), Coral (online) [Accessed 17/01/2021]. 6) Miller, E.C., Hayashi, K. T., Song, D., Wiens, J. J., (2018) Explaining the ocean’s richest biodiversity hotspot and global patterns of fish diversity. Proceedings of the Royal Society B 285: 20181314. 7) Jones, K. R., Klein, C. J., Halpern, B. S., Venter, O., Grantham, H., Kuempel, C. D., Shumway, N., Friedlander, A. M., Possingham, H. P. and Watson, J. E. M. (2018), The Location and Protection Status of Earth’s Diminishing Marine Wilderness. Current Biology 28: 2506- 2512.
As far as I am aware, the separate elements and studies that I mention have not been collated into one paper. So, although our discussion is based off scientific literature, it might potentially be best to view it as just that- a discussion. I mention this note of caution simply because I am not an expert in this field.
Building on our discussion of the Red Queen hypothesis last week, we’re going to go through a theorem which is similarly chess-themed but goes against our hypothesis from episode 20. This theory holds that, rather than continual evolution being necessary for a species to survive, natural selection can sometimes allow genes to be lost from the gene pool.
Sources for this episode: 1) Author unknown, Wikipedia (date unknown), Black Queen hypothesis (online) [Accessed 15/01/2021]. 2) Morris, J. J., Lenski, R. E. and Zinser, E. R. (2012), The Black Queen Hypothesis: Evolution of Dependencies through Adaptive Gene Loss. mBio 3(2): e00036-12. 3) Willey, J. M., Sherwood, L. M. and Woolverton, C. J. (2017), Prescott’s Microbiology (Tenth Edition, International Edition). New York: McGraw Hill Education. 4) Allen, R. C., Popat, R., Diggle, S. P. and Brown, S. P. (2014), Targeting virulence: can we make evolution-proof drugs? Nature Reviews Microbiology 12(4): 300- 308.
This week, I’m going to discuss the Red Queen Hypothesis, which sounds intimidating but is actually rather straightforward. Not only is it an evolutionary theory, but it’s also a reminder that biologists really like finding obscure reasons to name things…
Sources for this episode: 1) Author unknown, Wikipedia (date unknown), Red Queen Hypothesis (online) [Accessed 14/01/2021]. 2) Thain, M. and Hickman, M. (2004), The Penguin Dictionary of Biology (11th edition). London: Penguin Books Ltd. 3) Scoville, H., ThoughtCo (updated 2019), What Is the Red Queen Hypothesis? (online) [Accessed 14/01/2021].
Happy Darwin’s Day! On the anniversary of Darwin’s birthday on 12th February 1809, I thought it would be fun to release a special episode covering some aspect of Darwin’s life or theories. Today, we’re going to discuss the health of Darwin’s children and of Darwin’s immediate family, using a 2017 paper by Hayman et al.
Sources for this episode: 1) Hayman, J., Álvarez, G., Ceballos, F. C. and Berra, T. M. (2017), The illnesses of Charles Darwin and his children: a lesson in consanguinity. Biological Journal of the Linnean Society 121: 458- 468. Information on the immediate family of Charles Darwin can also be found on Wikipedia, whether his article or the article on the Darwin-Wedgewood family.
