Atmospheric hypoxia limits selection for large body size in insects
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- Arizona State University, School of Life Sciences
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This manuscript is a preprint. A published version is available at:
10.1371/journal.pone.0003876 (Peer Reviewed) Published in PLoS ONE. 2009;4(1):e3876.- Document Type:
- Manuscript
- Date:
- Received 24 April 2008 21:18 UTC; Posted 25 April 2008
- Subjects:
- Ecology, Evolutionary Biology
- Abstract:
Recent geological models indicate a marked increase in atmospheric oxygen partial pressure (aPO2) to 32 kPa in the Permo-Carboniferous (approx. 300 million years ago), subsequently falling to 13 kPa in the Triassic1.These aPO2 changes have been hypothesized to cause multiple major evolutionary events2 including the appearance and subsequent extinction of giant insects and other taxa3, 4. Patterns of increasing tracheal investment in larger insects support this hypothesis5, as do observations of positive relationships between aPO2 and body size in single- or multi-generational experiments with Drosophila melanogaster and other insects6. Large species likely result from many generations of selection for large body size driven by predation, competition or sexual selection7. Thus a crucial question is whether aPO2 influences the capacity of such selection to increase insect size. We tested that possibility by selecting for large body size in five Drosophila melanogaster populations for 11 generations in hypoxic (10 kPa), normoxic (21 kPa) and hyperoxic (40 kPa) aPO2, followed by three generations of normoxia without size selection to test for evolved responses. Average body sizes increased by 15% during 11 generations of size selection in 21 and 40 kPa aPO2 flies and even stronger responses were observed for the flies in the largest quartile of body masses. However, flies selected for large size in 10 kPa aPO2 had strongly reduced sizes compared to those in higher aPO2. Upon return to normoxia, all flies had similar, enlarged sizes relative to the starting populations. These results demonstrated that positive size selection had equivalent genetic effects on all flies independent of aPO2, but that hypoxia provided a physical constraint on body size even in a relatively small insect under strong selection for larger mass. Our data support the hypothesis that Triassic hypoxia may have contributed to a reduction in insect size.
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- License:
- This document is licensed to the public under the Creative Commons Attribution 3.0 License
- How to cite this document:
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Klok, C Jaco and Harrison, Jon. Atmospheric hypoxia limits selection for large body size in insects. Available from Nature Precedings <http://hdl.handle.net/10101/npre.2008.1831.1> (2008)
- Version info:
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Published version:
10.1371/journal.pone.0003876 (Peer Reviewed) Published in PLoS ONE. 2009;4(1):e3876. -
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