This month’s highlights blog features all the best content published in our research journals in June. This month we have: mimicry mechanisms in Mocker Swallowtails, D-I-S-C-O, secret role of cell component unfolded, kids outsmart crows, swimming against the tide and it pays to be the best counterfeit.
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Batesian mimics copy the colouring of poisonous or foul-tasting species even though they themselves would make a perfectly tasty meal. However, to prevent the phenotype becoming too common, which would cause predators to associate the colouring with breakfast, the imposters show polymorphism. The African Mocker Swallowtail butterfly is a typical example of this cheeky bit of evolutionary genetics, with the females showing a diverse array of colour morphs in different regions. This Proceedings B paper uses various modern genomics techniques to investigate the genetic control of mimicry in these butterflies and favours the hypothesis that wing pattern polymorphism is caused by a single gene. Interestingly this contradicts a previous body of work which proposes that many genes control the various mimicry forms.
The ‘disco’ clam is one of only a few organisms that uses nanospheres of silica to reflect light. This light display is so vivid it was previously believed to be bioluminescence but is actually the result of scattered light, as reported in the Journal of the Royal Society Interface. The authors reveal two distinct tissue sides on the clam’s mantle lip: one highly scattering side densely lined with nanoparticles of silica, and one highly absorbing side that does not; the flashing occurs as the calm rapidly rolls and unrolls its lips exposing the dark and reflective sides in turn several times a second. The function of this disco signal is yet to be confirmed. One possibility is to attract mates from across the dance (ocean) floor…
Secret role of cell component unfolded
Present in all eukaryotes, prefoldin is an important component of the cell. This family of proteins is part of a molecular chaperone system that promotes the correct folding of polypeptide chains and participates in the assembly of a filament network that constitutes the cell skeleton. In addition to this function, there is increasing evidence of a second role: its contribution to the transcription of genes in the cell nucleus. In a new review article published in Open Biology, researchers based at the University of Seville put together extensive evidence on the involvement of prefoldin in nuclear phenomena which supports this second function and discuss the possible coordinated contribution of the two functions of prefoldin to global cell regulation.
Kids outsmart crows
Do tool-wielding New Caledonian crows show the same causal intervention behaviour (the ability to learn a cause-effect relationship through just observation) which makes humans human ? It has been suggested that the comprehension behind tool-use, for instance to obtain food is evolutionarily linked to causal understanding. A recent paper in Proceedings B examines how 24-month-old children (the age at which causal intervention appears in humans) and New Caledonian crows behave when they are presented with a box containing a treat. Whilst both children and crows could decipher how to acquire their treat through experience, only the children, when put in a different situation could use what they had observed to be rewarded. This suggests that causal intervention and causal understanding are evolutionarily distinct.
The Earth is unusual amongst planets in having a sun and moon that exert very similar tidal forces upon it. This paper in Proceedings A presents an argument that the combined forces helped primitive life move from the oceans onto land in the Devonian period. The variation in ocean tide patterns generated by the sun and the moon would have been conducive to the formation of a vast network of isolated tidal pools. To avoid desiccation, tetrapods trapped in inland pools would have been selected for manoeuvrability on land, and the development of nascent limbs. The paper goes on to suggest that since even a modest difference in the Moon’s angular size relative to the Sun’s would lead to a qualitatively different tidal modulation, the fact that we live on a planet with a Sun and Moon of close apparent size is not entirely coincidental: it may have an anthropic basis.
Batesian mimicry is observed between sympatric venomous coral snakes and their impersonators, the non-venomous scarlet king snakes. New research published in Biology Letters last month shows that even after the local extinction of coral snakes in the North Carolina Sandhills, the king snakes have continued to evolve more similar patterning to the coral snake, thus deceiving their predators who will avoid a potentially deadly meal. In this case, the authors suggest that in the long term this mimicry will break down, as more predator generations pass. However the evolutionary momentum driven by the strong selection pressure of predation has caused this phenomenon to continue even in absence of the model coral snakes.