Tipsheet for the May issue of the American Naturalist

(Press-News.org) Article highlights from the May issue of The American Naturalist: Cuttlefish: From camo to tuxedo in less than a second Genes control fruit flies' social groupings What can twins tell us about mate choice?

For the full May issue table of contents, go to www.journals.uchicago.edu/an. For more information or for photos (where available), contact Kevin Stacey: kstacey@press.uchicago.edu.

Cuttlefish: From camo to tuxedo in less than a second

Cuttlefish have the amazing ability to instantly change their color and body pattern so they can hide from predators or, alternatively, broadcast their presence to potential mates. A new study led by Sarah Zylinski of Duke University shows just how good these animals (relatives of octopus and squid) are at this quick change routine. Using sophisticated image analysis techniques, Zylinski and her team compared the color patterns of cuttlefish to patterns in their surroundings, both when the animals were hiding and when they were signaling. "The analysis shows that the cuttlefish are able to match intricate visual characteristics of their aquatic environments to maximize their camouflage against the visual systems of their vertebrate predators," Zylinski said. "However, in the presence of females, the males adopt body patterns that deviate from their immediate environment and make themselves maximally conspicuous." The research also suggests that cuttlefish may seek out simpler backgrounds when attempting to signal. [Photos available]

S. Zylinski (University of Sussex and Duke University), M. J. How (University of Queensland), D. Osorio (University of Sussex), R. T. Hanlon (Woods Hole Marine Biology Laboratory), and N. J. Marshall (University of Queensland), "To Be Seen Or To Hide: Visual Characteristics of Body Patterns for Camouflage and Communication in the Australian Giant Cuttlefish, Sepia apama"

Genes control fruit flies' social groupings

A new study reveals how a fruit fly's genes can influence the company it keeps. Using male flies that had been bred for varying levels of aggressiveness, researchers Julia Saltz and Brad Foley observed how the males formed groups when placed into an enclosure with females. The research showed that the non-aggressive flies clumped together, forming a few large groups. The aggressive flies, meanwhile, spread out into smaller groups. This sorting according to behavioral preference is known as social niche construction (SNC), and Saltz says this is the first time it has been demonstrated to have a genetic basis. In sorting themselves this way, both aggressive and non-aggressive flies were able to find mating success. Some flies were more likely to mate after winning an aggressive conflict. Those flies benefitted from being aggressive. Other flies however were more likely to mate after losing a squabble. Those flies benefitted from forgoing aggression. "Thus, successful males were those who 'used' SNC to generate the social environment in which they are most adept at mating," explains Saltz, a Ph.D. student and lead author on the paper. "Non-aggressive genotypes aren't just 'broken' males. They're pursuing an alternate social strategy."

Julia B. Saltz (University of Southern California and University of California, Davis) and Brad R. Foley (University of Southern California), "Natural Genetic Variation in Social Niche Construction: Social Effects of Aggression Drive Disruptive Sexual Selection in Drosophila melanogaster"

What can twins tell us about mate choice?

What factors influence our choice of a mate? Is it our genes? Does a man look for someone like his mother and a woman someone her father? None of the above, according to a study of Australian twins. Researchers from the University of Queensland found that for traits including body size, personality, age, social attitudes, and religiosity, identical twins did not tend to have similar spouses, after accounting for the fact that spouse pairs (and twins pairs) themselves tend to be similar. The results suggest that genes don't have much direct influence on mate choice for these traits. As for whether people choose a mate like their opposite-sex parent, that doesn't appear to be the case either. A twin's spouse was much more similar to the twin and co-twin than the twin's opposite-sex parent.

Brendan P. Zietsch (University of Queensland and Queensland Institute of Medical Research), Karin J. H. Verweij (University of Queensland and Queensland Institute of Medical Research), Andrew C. Heath (Washington University School of Medicine, St. Louis), and Nicholas G. Martin (Queensland Institute of Medical Research), "Variation in Human Mate Choice: Simultaneously Investigating Heritability, Parental Influence, Sexual Imprinting, and Assortative Mating"

### Since its inception in 1867, The American Naturalist has maintained its position as one of the world's most renowned, peer-reviewed publications in ecology, evolution, and population and integrative biology research.