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Grasshopper ontogeny in relation to time constraints: adaptive divergence and stasis


Berner, D; Blanckenhorn, Wolf U (2006). Grasshopper ontogeny in relation to time constraints: adaptive divergence and stasis. Journal of Animal Ecology, 75(1):130-139.

Abstract

1. Life history theory generally predicts a trade-off between short juvenile development and large adult size, assuming invariant growth rates within species. This pivotal assumption has been explicitly tested in few organisms.
2. We studied ontogeny in 13 populations of Omocestus viridulus grasshoppers under common garden conditions. High-altitude populations, facing short growing seasons and thus seasonal time constraints, were found to grow at a similar rate to low altitude conspecifics.
3. Instead, high-altitude grasshoppers evolved faster development, and the correlated change in body size led to an altitudinal size cline mediating a trade-off with female fecundity.
4. An additional juvenile stage occurred in low- but not high-altitude females. This difference is probably due to the evolution of lowered critical size thresholds in high-altitude grasshoppers to accelerate development.
5. We found a strikingly lower growth rate in males than females that we interpret as the outcome of concurrent selection for protandry and small male size.
6. Within populations, large individuals developed faster than small individuals, suggesting within-population genetic variation in growth rates.
7. We provide evidence that different time constraints (seasonal, protandry selection) can lead to different evolutionary responses in intrinsic growth, and that correlations among ontogenetic traits within populations cannot generally be used to predict life history adaptation among populations. Moreover, our study illustrates that comparisons of ontogenetic patterns can shed light on the developmental basis underlying phenotypic evolution.

Abstract

1. Life history theory generally predicts a trade-off between short juvenile development and large adult size, assuming invariant growth rates within species. This pivotal assumption has been explicitly tested in few organisms.
2. We studied ontogeny in 13 populations of Omocestus viridulus grasshoppers under common garden conditions. High-altitude populations, facing short growing seasons and thus seasonal time constraints, were found to grow at a similar rate to low altitude conspecifics.
3. Instead, high-altitude grasshoppers evolved faster development, and the correlated change in body size led to an altitudinal size cline mediating a trade-off with female fecundity.
4. An additional juvenile stage occurred in low- but not high-altitude females. This difference is probably due to the evolution of lowered critical size thresholds in high-altitude grasshoppers to accelerate development.
5. We found a strikingly lower growth rate in males than females that we interpret as the outcome of concurrent selection for protandry and small male size.
6. Within populations, large individuals developed faster than small individuals, suggesting within-population genetic variation in growth rates.
7. We provide evidence that different time constraints (seasonal, protandry selection) can lead to different evolutionary responses in intrinsic growth, and that correlations among ontogenetic traits within populations cannot generally be used to predict life history adaptation among populations. Moreover, our study illustrates that comparisons of ontogenetic patterns can shed light on the developmental basis underlying phenotypic evolution.

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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)
Date:2006
Deposited On:27 Jul 2009 07:17
Last Modified:05 Apr 2016 13:18
Publisher:Wiley-Blackwell
ISSN:0021-8790
Additional Information:Author Posting. © The Authors 2006 The full text of this article is published in Journal of Animal Ecology, 75:1 (2006) p. 130-139. It is available online from Blackwell-Synergy at http://dx.doi.org/10.1111/j.1365-2656.2005.01028.x. Note: N.B.The full text of the Article will be made freely available via Blackwell-Synergy 2 years after publication.
Publisher DOI:https://doi.org/10.1111/j.1365-2656.2005.01028.x

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