cE3c researchers comment an (apparently) maladaptive case of sex allocation in the latest issue of Current Biology

12/06/2016. Text by Marta Daniela Santos.

cE3c researchers João Alpedrinha and Sara Magalhães have just published a dispatch in the prestigious scientific jornal Current Biology commenting on a new study (*) that challenges the ubiquity of the predictive success of sex allocation theory – the study of how sexual organisms allocate resources into the number and quality of daughters and sons.

The Fisherian prediction (after the evolutionary biologist Robert Fisher) for large and unstructured populations, in which mating is random, is that parents will allocate the same resources for the production of male and female offspring. If the population is structured and there are few founding females, however, a female-biased sex ratio is predicted – a paradigmatic example known as the “theory of local mate competition”.

The study under analysis, by Lievens et al. (*), reports an (apparently) maladaptive sex allocation in the invasive brine shrimp Artemia franciscana, which naturally spreads through the Americas (in particular saline lakes) where it produces an even sex ratio. However, invasive populations of A. franciscana have also been observed in Europe, Asia, Madagascar, North Africa and Australia. In the Mediterranean region it shares its habitat with Artemia parthenogenetica, an old-world parthenogenetic brine shrimp composed exclusively of females that reproduce without the need of fertilization by a male gamete.

In the populations found in the Mediterranean region, Lievens et al. found that A. franciscana produce a male-biased sex ratio. Both in natural populations from the invasive range and by experimentally exposing A. franciscana to an excess of females, Lievens et al show that the sex allocation of A. franciscana responds to the combined number of conspecific and heterospecific females in an almost Fisherian mode. As a result, the sex ratio of A. franciscana becomes male-biased when accounting for conspecific males and females only.

João Alpedrinha and Sara Magalhães argue that this excess of male offspring may not be maladaptive but instead a response to the reproductive interference observed. Males engaging in reproductive interactions with females of another species will be unavailable to mate with females of their own species. Therefore, a female producing an excess of male offspring is actually increasing the probability of having a son coupling with a female of his own species. That is, she is increasing the probability of transmitting her genes to future generations.


(*) Lievens, E. J., Henriques, G. J, Michalakis, Y., Lenormand, T. (2016) Maladaptive Sex Ratio Adjustment in the Invasive Brine Shrimp Artemia franciscana. Current Biology Vol. 26, Issue 11, pp.1463-1467.


Complete reference to the article:

Alpedrinha, J., Magalhães, S. (2016) Sex Allocation: L’Enfer C’est les Autres? Current Biology Vol. 26, Issue 11, pp. R476-R48.


Photo by Thomas Lenormand.

Tags: EE

Other Articles

  • Um musgo invasor e a sua história não contada… ou melhor, nunca ouvida!

    Paper Folha de calendário SEBICOP - Um musgo invasor

  • Iconic examples of the outstanding and unique biodiversity found on islands worldwide

    Paper Scientists warn: the unique biodiversity of islands is in peril!

  • Infografia: Jagoba Malumbres-Olarte

    Paper New IBBC Study Shows of the Role of Habitat Type and Dispersal for Island Biodiversity

  • IUCN’s New “Green Status of Species” Measures Impact of Conservation Action

    Paper IUCN’s New “Green Status of Species” Measures Impact of Conservation Action

  • Ruído dos barcos no Tejo está a abafar o canto dos xarrocos

    Paper Ruído dos barcos no Tejo está a abafar o canto dos xarrocos