Current address: Zoologisches Museum der Universität Zürich-Irchel, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
Life history adaptation along a latitudinal cline in the water strider Aquarius remigis (Heteroptera: Gerridae)
Article first published online: 11 DEC 2002
Journal of Evolutionary Biology
Volume 8, Issue 1, pages 21–41, January 1995
How to Cite
Blanckenhorn, W. U. and Fairbairn, D. J. (1995), Life history adaptation along a latitudinal cline in the water strider Aquarius remigis (Heteroptera: Gerridae). Journal of Evolutionary Biology, 8: 21–41. doi: 10.1046/j.1420-9101.1995.8010021.x
- Issue published online: 11 DEC 2002
- Article first published online: 11 DEC 2002
- Received 17 June 1994 Accepted 12 August 1994
- Cited By
- Body size;
- life history trade-off;
- phenotypic plasticity;
- season length
We addressed the general hypothesis that life history differences among eastern populations of the North American water strider, Aquarius remigis (Heteroptera: Gerridae), along a north-south gradient are manifestations of genetic differentiation due to natural selection. We raised offspring of two field-caught populations from each of three latitudes in a common laboratory environment at 20° C and two photoperiods. Nearly all Quebec (PQ) individuals (ca. 46° N) entered diapause to reproduce the following spring (univoltine life cycle), while intermediate proportions of New York (NY; ca. 43° N) and New Jersey (NJ; ca. 41° N) individuals reproduced directly, producing a second generation (bivoltine life cycle). PQ females were smaller, developed faster, and laid smaller eggs than NY and NJ individuals; NY and NJ populations differed little in these variables. NY females had longer life spans than either PQ or NJ females, but lower oviposition rates. Total reproductive output did not differ across latitudes. Photoperiod affected body length, development time, and reproductive pathway, resulting in a latitude by environmental interaction. PQ individuals reproduced directly under 15L : 9D (summer) conditions only, while the NY and NJ populations exhibited more direct reproduction under 13L : 11D (spring or fall) conditions. Some life history characters of the NY and NJ populations displayed the higher variability indicative of phenological transition zones. These results indicate local adaptation of populations to long-term climatic patterns. Water striders appear to adapt to longer seasons by extending development, growing larger, and breeding directly. Larger body size and extended or rapid development are associated with bivoltinism and increase in egg size, but not necessarily with higher fecundity or oviposition rate. The phenological transition zone appears to be unrelated to a transition zone a little further south established by allozyme data and morphology, as all populations studied here could be electrophoretically identified as northern "type".