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Altitudinal life history variation in the dung flies Scathophaga stercoraria and Sepsis cynipsea


Blanckenhorn, Wolf U (1997). Altitudinal life history variation in the dung flies Scathophaga stercoraria and Sepsis cynipsea. Oecologia, 109(3):342-352.

Abstract

Field phenologies of high- (ca. 1500 m) and low- (ca. 500 m) altitude populations of the two most common European species of dung flies, Scathophaga stercoraria and Sepsis cynipsea, differ quite markedly due to differences in climate. To differentiate genetic adaptation due to natural selection and phenotypic plasticity, I compared standard life history characters of pairs of high- and low-altitude populations from three disjunctive sites in Switzerland in a laboratory experiment. The F1 rearing environment did not affect any of the variables of the F2 generation with which all experiments were conducted; hence, there were no carry-over or maternal effects. In Sc. stercoraria, high-altitude individuals were smaller but laid larger eggs; the latter may be advantageous in the more extreme (i.e. more variable and less predictable) high-altitude climate. Higher rearing temperature strongly decreased development time, body size and the size difference between males and females (males are larger), produced female-biased sex ratios and led to suboptimal adult emergence rates. Several of these variables also varied among the three sites, producing some interactions complicating the patterns. In Se. cynipsea, high-altitude females were marginally smaller, less long-lived and laid fewer clutches. Higher rearing temperature strongly decreased development time and body size but tended to increase the size difference between males and females (males are smaller); it also increased clutch size but decreased physiological longevity. Again, interpretation is complicated by variation across sites and some significant interactions. Overall, genetic adaptation to high-altitude conditions appears weak, probably prevented by substantial gene flow, and may be swamped by the effects of other geographic variables among populations. In contrast, phenotypic plasticity is extensive. This may be due to selection of flexible, multi-purpose genotypes. The results suggest that differences in season length between high- and low-altitude locations alone do not explain well the patterns of variation in phenology and body size.

Abstract

Field phenologies of high- (ca. 1500 m) and low- (ca. 500 m) altitude populations of the two most common European species of dung flies, Scathophaga stercoraria and Sepsis cynipsea, differ quite markedly due to differences in climate. To differentiate genetic adaptation due to natural selection and phenotypic plasticity, I compared standard life history characters of pairs of high- and low-altitude populations from three disjunctive sites in Switzerland in a laboratory experiment. The F1 rearing environment did not affect any of the variables of the F2 generation with which all experiments were conducted; hence, there were no carry-over or maternal effects. In Sc. stercoraria, high-altitude individuals were smaller but laid larger eggs; the latter may be advantageous in the more extreme (i.e. more variable and less predictable) high-altitude climate. Higher rearing temperature strongly decreased development time, body size and the size difference between males and females (males are larger), produced female-biased sex ratios and led to suboptimal adult emergence rates. Several of these variables also varied among the three sites, producing some interactions complicating the patterns. In Se. cynipsea, high-altitude females were marginally smaller, less long-lived and laid fewer clutches. Higher rearing temperature strongly decreased development time and body size but tended to increase the size difference between males and females (males are smaller); it also increased clutch size but decreased physiological longevity. Again, interpretation is complicated by variation across sites and some significant interactions. Overall, genetic adaptation to high-altitude conditions appears weak, probably prevented by substantial gene flow, and may be swamped by the effects of other geographic variables among populations. In contrast, phenotypic plasticity is extensive. This may be due to selection of flexible, multi-purpose genotypes. The results suggest that differences in season length between high- and low-altitude locations alone do not explain well the patterns of variation in phenology and body size.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Scopus Subject Areas:Life Sciences > Ecology, Evolution, Behavior and Systematics
Uncontrolled Keywords:Ecology, Evolution, Behavior and Systematics
Language:English
Date:7 February 1997
Deposited On:22 Aug 2019 12:56
Last Modified:31 Jul 2020 03:32
Publisher:Springer
ISSN:0029-8549
OA Status:Closed
Publisher DOI:https://doi.org/10.1007/s004420050092

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