Evolutionary Genetics Group projects

Current projects:

  • Genetics and evolution of coloration in birds
  • Co-evolution of colour vision and coloration in birds and other vertebrates
  • The evolution and function of colour vision in primates

 

Zebra Finch

Genetics and evolution of coloration in birds

We are interested in the molecular genetics of coloration in birds, and the insights this gives into sexual selection, avian diversification and the co-evolution of colour vision and coloration.

We recently identified a gene for bright red carotenoid coloration expressed in the beaks of zebra finches (CYP2J19, Mundy et al. 2016) that is opening up many new avenues of research.

We are performing a comparative study of the evolution of expression of CYP2J19 in weavers in relation to red coloration, which is an agonistic signal in males. We are also tracing the evolution of the duplication of CYP2J19 locus that is present in zebra finches, to understand the functional consequences of the duplication.

References

Twyman, H., Prager, M., Mundy, N. I. and S. Andersson (2018) Expression of a  carotenoid-modifying gene and the evolution of red coloration in ploceids. Mol. Ecol. (in press).

Mundy, N. I., Stapley, J., Bennison, C., Tucker, R., Twyman, H., Kim, K-W., Burke, T. A., Birkhead, T. R., Andersson, S., and J. Slate (2016) Red carotenoid  coloration in the zebra finch is controlled by a cytochrome P450 gene cluster. Current Biology26, 1435-1440. DOI: 10.106/j.cub.2016.04.047      

Twyman, H., Valenzuela, N., Literman, R., Andersson, S. and N. I. Mundy (2016) Seeing red to being red: conserved genetic mechanism for red cone oil droplets and co-option for red coloration in birds and turtles. Proc. Roy Soc. B 283, 20161208. DOI:10.1098/rspb.2016.1208

 

montage of a zebra finch and a turtle.

Co-evolution of colour vision and coloration in birds and other vertebrates

Our recent work is converging on the relationship between red coloration and colour vision in various vertebrates. 

We found that the CYP2J19 locus that underlies red carotenoid coloration in birds first evolved in the archelosaur lineage, the clade containing birds, turtles, crocodiles and dinosaurs (Twyman et al. 2016). However, the first function of CYP2J19 was not in red coloration, but for the carotenoid-containing red oil droplets in cones in the retina. These red droplets act as filters in long-wave sensitive cones and lead to improved colour discrimination at long wavelengths. In birds and turtles, CYP2J19 independently gained a second function for red coloration. 

Meanwhile, our work on colour vision in bald uakaris (further details here) has raised the intriguing possibility that female colour vision has evolved to identify healthy males from the intensity of red coloration of their heads.

We are now investigating potential coevolution of colour vision and coloration in poison-dart frogs, and weavers.

Reference

Twyman, H., Valenzuela, N., Literman, R., Andersson, S. and N. I. Mundy (2016) Seeing red to being red: conserved genetic mechanism for red cone oil droplets and co-option for red coloration in birds and turtles. Proc. Roy Soc. B 283, 20161208. DOI:10.1098/rspb.2016.1208

 

The evolution and function of colour vision in primates

We are interested in adaptive explanations for the high diversity of colour vision within and between primate species.

We recently found that the bald uakari (above) has the highest intraspecific variation in colour vision of any wild primate (Corso et al. 2016). Like most other New World monkeys, male bald uakaris are red-green colourblind (dichromat) where many females are trichromats. This variation has a simple genetic basis, due to a single polymorphic photopigment (opsin) locus on the X chromosome. The presence of 5 or possibly 6 functional X-linked opsin alleles in uakaris means that a higher proportion of females will be trichromatic. We propose that trichromatic females are better at distinguishing healthy males via the redness of their heads. In support of this idea, uakaris have the highest prevalence of two blood-borne parasites of any New World monkey.

We also recently investigated whether an unusual population of owl monkeys that is active during the daytime has re-evolved colour vision. We found that, like their relatives, Azara's owl monkeys are still completely colour-blind, which is likely an important ecological constraint (Mundy et al. 2016).

We are currently investigating colour vision in other uakaris, common marmosets and many diurnal lemurs.

References

Corso, J., Bowler, M., Heymann, E. W., Roos, C., and  N. I. Mundy (2016) Highly polymorphic colour vision in a New World monkey with red facial skin, the bald uakari (Cacajao calvus) Proc. Roy Soc. B.283, 20160067.

Mundy, N. I., Morningstar, N. C., Baden, A. L., Fernandez-Duque, E., Dávalos, V. M. and B. J. Bradley (2016) Can colour vision re-evolve? Variation in the X-linked opsin locus of cathemeral Azara’s owl monkeys(Aotus azarae azarae) Frontiers Zool. 13, 9. DOI 10.1186/s12983-016-0139-z