Rapid evolution of a sexual signal in the field cricket, Teleogryllus oceanicus
The dulcet tones of cricket song that we find so relaxing on warm evenings are actually
the advertisement calls of sexually receptive males. A nasty threat looms over
Teleogryllus oceanicus populations in Hawaii, however. A villain of the blackest dye, the
parasitoid fly Ormia ochracea, emerges at night to prey on hapless male crickets. Female
flies hone in on male cricket song, and squirt live larvae onto their hosts. Larvae then
burrow through the cuticle and feast on various internal cricket structures. After a week
or so, the engorged, pulsing maggots burst out of their host, leaving a hollow cricket
husk behind. Clearly, this is not a desirable situation to be in if you are a male
cricket. Our research team has recently made an astonishing discovery on the Hawaiian
island of Kauai
In 2003, an eerie silence had descended on the population. Had all the males ceased calling? Had the population gone extinct? After some investigation, we discovered that a dramatic morphological mutation had arisen in some males, causing the loss of sound-producing structures on their wings (larger image). These flatwing males are protected from predation by acoustically orienting parasitoids. The proportion of flatwing males on Kauai has increased from zero to nearly 90 percent in fewer than 30 generations, representing one of the fastest evolutionary shifts documented in a wild population. We are currently investigating the extent to which pre-existing behaviors facilitated the emergence and spread of this mutation, providing new and exciting insights into the interactions between behavior and evolutionary change.
Our work on this system now features in the most recent edition of "Principles of Animal
Behavior" by LA Dugatkin. For further reading, check out:
- Bailey, N.W. and Zuk, M. (2008) Acoustic experience shapes female mate choice in field crickets. Proceedings of the Royal Society of London, B 275: 2645-2650. [pdf]
- Bailey, N.W., McNabb, J.R. and Zuk, M. (2008) Pre-existing behavior facilitated the loss of a sexual signal in the field cricket Teleogryllus oceanicus. Behavioral Ecology 19: 202-207. [pdf]
- Tinghitella, R.M. (2008) Rapid evolutionary change in a sexual signal: genetic control of the mutation 'flatwing' that renders male field crickets (Teleogryllus oceanicus) mute. Heredity 100: 261-267. [pdf]
- Zuk, M., Rotenberry, J.T., and Tinghitella, R.M. (2006). Silent night: Adaptive disappearance of a sexual signal in a parasitized population of field crickets. Biology Letters 2: 521-524. [pdf]
Evolution of Sex Differences in Disease Susceptibility
In many animal species, females have more robust immunity and are less likely to harbor
parasites than males. Why is that? Comparative and theoretical work from current and
former lab members has examined the evolutionary causes of sex-biased parasitism and
immune responses, placing these traits in the context of sexual selection. Check out:
- Stoehr, A.M. and Kokko, H. (2007) Sexual dimorphism in immunocompetence: what doeslife-history theory predict? Behavioral Ecology 17:751-756.
- McKean, K. and M. Zuk. (1995) The evolution of signaling in immunology and behavior.Naturwissenschaften 82:509-516.
- Zuk, M. (1990) Reproductive strategies and sex differences in disease susceptibility: anevolutionary viewpoint. Parasitology Today 6:231-233.
Sex and Gender in Humans and Animals
Those of us who study sexual behavior in animals have noticed that people like to apply
what we learn to their own behavior. We often get people asking questions like, "Is
monogamy natural?" or "Does homosexuality exist in non-humans?" Marlene Zuk and others in
the lab enjoy interacting with other scientists as well as the general public in
discussions of these and related issues, and if you are interested, you can check out some
of the following:
- Zuk, M. (2006) Family values in black and white. Nature 439:917.
- Zuk, M. (2004) Birds do it, bonobos do it (opinion). Los Angeles Times, March 7, M3.
- Zuk, M. (2004) Make way for genes and ducklings. Chronicle of Higher Education, January 9, 2004 B13-B14.
- Zuk, M. (2003) Why not save jellyfish as well as whales? Chronicle of Higher Education, March 21, 2003 B13-B14.
- Zuk, M. (2002) Sexual Selections: what we can and can't learn about sex from animals. University of California Press, Berkeley.
- Zuk, M. (2002) Birds do it (opinion article). Los Angeles Times, June 2, 2002, M6.
- Zuk, M. (2002) A straw man on a dead horse: Studying adaptation then and now. Commentary on Andrews et al.: Adaptationism: How To Carry Out an Exaptationist Program. (invited contribution) Behavioral and Brain Sciences 25: 533-534.
- Zuk, M. (2002) Can nature be declawed? Natural History, 10/02: 38-41.
- Zuk, M. (1997) Darwinian medicine dawning in a feminist light. Pp. 417-430 in: Feminism and evolutionary biology: boundaries, intersections, and frontiers (P.A. Gowaty, ed.). Chapman and Hall, New York.
- Zuk, M. (1993) Feminism and the study of animal behavior. BioScience 43:774-778.