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Body size evolution in an old insect order : No evidence for Cope's Rule in spite of fitness benefits of large size

Waller, John T. LU and Svensson, Erik I. LU (2017) In Evolution
Abstract

We integrate field data and phylogenetic comparative analyses to investigate causes of body size evolution and stasis in an old insect order: odonates ("dragonflies and damselflies"). Fossil evidence for "Cope's Rule" in odonates is weak or nonexistent since the last major extinction event 65 million years ago, yet selection studies show consistent positive selection for increased body size among adults. In particular, we find that large males in natural populations of the banded demoiselle (Calopteryx splendens) over several generations have consistent fitness benefits both in terms of survival and mating success. Additionally, there was no evidence for stabilizing or conflicting selection between fitness components within the adult... (More)

We integrate field data and phylogenetic comparative analyses to investigate causes of body size evolution and stasis in an old insect order: odonates ("dragonflies and damselflies"). Fossil evidence for "Cope's Rule" in odonates is weak or nonexistent since the last major extinction event 65 million years ago, yet selection studies show consistent positive selection for increased body size among adults. In particular, we find that large males in natural populations of the banded demoiselle (Calopteryx splendens) over several generations have consistent fitness benefits both in terms of survival and mating success. Additionally, there was no evidence for stabilizing or conflicting selection between fitness components within the adult life-stage. This lack of stabilizing selection during the adult life-stage was independently supported by a literature survey on different male and female fitness components from several odonate species. We did detect several significant body size shifts among extant taxa using comparative methods and a large new molecular phylogeny for odonates. We suggest that the lack of Cope's rule in odonates results from conflicting selection between fitness advantages of large adult size and costs of long larval development. We also discuss competing explanations for body size stasis in this insect group.

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author
organization
publishing date
type
Contribution to journal
publication status
epub
subject
keywords
Body size, Comparative methods, Natural selection, Odonata, Phylogenetics, Sexual selection, Stasis
in
Evolution
publisher
Wiley-Blackwell
external identifiers
  • scopus:85026504315
ISSN
0014-3820
DOI
10.1111/evo.13302
language
English
LU publication?
yes
id
7986c049-99ae-41a5-96e6-f5cf985a5340
date added to LUP
2017-09-01 13:49:46
date last changed
2017-09-02 03:00:02
@article{7986c049-99ae-41a5-96e6-f5cf985a5340,
  abstract     = {<p>We integrate field data and phylogenetic comparative analyses to investigate causes of body size evolution and stasis in an old insect order: odonates ("dragonflies and damselflies"). Fossil evidence for "Cope's Rule" in odonates is weak or nonexistent since the last major extinction event 65 million years ago, yet selection studies show consistent positive selection for increased body size among adults. In particular, we find that large males in natural populations of the banded demoiselle (Calopteryx splendens) over several generations have consistent fitness benefits both in terms of survival and mating success. Additionally, there was no evidence for stabilizing or conflicting selection between fitness components within the adult life-stage. This lack of stabilizing selection during the adult life-stage was independently supported by a literature survey on different male and female fitness components from several odonate species. We did detect several significant body size shifts among extant taxa using comparative methods and a large new molecular phylogeny for odonates. We suggest that the lack of Cope's rule in odonates results from conflicting selection between fitness advantages of large adult size and costs of long larval development. We also discuss competing explanations for body size stasis in this insect group.</p>},
  author       = {Waller, John T. and Svensson, Erik I.},
  issn         = {0014-3820},
  keyword      = {Body size,Comparative methods,Natural selection,Odonata,Phylogenetics,Sexual selection,Stasis},
  language     = {eng},
  publisher    = {Wiley-Blackwell},
  series       = {Evolution},
  title        = {Body size evolution in an old insect order : No evidence for Cope's Rule in spite of fitness benefits of large size},
  url          = {http://dx.doi.org/10.1111/evo.13302},
  year         = {2017},
}