Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Body Size Evolution in Butterflies
Stockholm University, Faculty of Science, Department of Zoology.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Life history research deals with the scheme of resource partitioning to a wide spectra of processes and the trade-offs shaping these events. One of the most fundamental life history trade-offs is the one of at which age- and size an organism should start to reproduce; reaching a large size at maturity is often advantageous in terms of high adult survival and reproductive potential, while to attain a larger size the organisms must prolong juvenile development which is assumed costly in terms of mortality. In holometabolous insects, a larger size usually confers increased fitness to females in terms of fecundity. Moreover, insect larvae have the capacity for fast size increase. So, it seems that there are substantial fitness benefits associated with a choice to prolong development. Surprisingly, there is a great lack of empirical support for costs of such a choice and by incorporating these observations into a life history framework one arrives at the conclusion that insect body sizes should be several times larger than observed. I study body size evolution in butterflies by closely examining the fitness consequences of variation in the age- and size at maturity. By combining both laboratory and field measures of size-fitness relationships with standard life history modelling, I arrive at the main conclusions; 1: positive size dependent predation on larvae might a) significantly increase the cost of attaining a larger size at maturity, or b) induce risk sensitive foraging responses so to slow larval growth rates and thereby restrict size at maturity, 2: ecological factors might constrain female fecundity by inducing time limitation on large females that need more time to convert all their resources into offspring, making reproductive value increase at a slower rate than body size with increased larval growth effort. These mechanisms may help to explain the inconsistency between natural observations and theoretical predictions of life history variation in insects.

Place, publisher, year, edition, pages
Stockholm: Zoologiska institutionen , 2008. , 120 p.
Keyword [en]
Body size evolution, age- and size at maturity, life history theory, fecundity, predation risk, juvenile growth rate, Lepidoptera
National Category
Biological Sciences
Research subject
Animal Ecology
Identifiers
URN: urn:nbn:se:su:diva-7498ISBN: 978-91-7155-635-6 (print)OAI: oai:DiVA.org:su-7498DiVA: diva2:198426
Public defence
2008-05-16, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 8 A, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2008-04-24 Created: 2008-04-16 Last updated: 2010-01-13Bibliographically approved
List of papers
1. What keeps insects small? - Size dependent predation on two species of butterfly larvae
Open this publication in new window or tab >>What keeps insects small? - Size dependent predation on two species of butterfly larvae
2006 (English)In: Evolutionary Ecology, ISSN 0269-7653, Vol. 20, no 6, 575-589 p.Article in journal (Refereed) Published
Abstract [en]

Insect size usually increases greatly in the latter stages of development, while reproductive value increases strongly with adult size. Mechanisms that can balance the benefits associated with increased growth are poorly understood, raising the question: what keeps insects from becoming larger? If predation risk was to increase with juvenile size, it would make an extension of development very risky, favouring smaller final sizes. But field measures of juvenile mortality seldom show any general patterns of size dependence. We here therefore try to estimate a mechanistic relationship between juvenile size and predation risk by exposing the larvae of two closely related butterflies to a generalist invertebrate predator in a laboratory experiment. Predation risk increased with larval size but was not affected by the species-specific growth rate differences. These results indicate that predation risk may increase with the size of the juvenile even when predators are relatively small. By basing a model simulation on our data we also show that size dependent predation of the kind found in this study has potential to stabilise selection on body size in these species. Thus, these findings suggest that more detailed studies of the size dependence of predation risk on juvenile instars will increase the understanding of what it is that keeps insects small.

Keyword
life history; body size; growth rate; juvenile mortality; age- and size at maturity; predation risk; lepidoptera; model
National Category
Ecology Ecology
Identifiers
urn:nbn:se:su:diva-14396 (URN)doi:10.1007/s10682-006-9118-8 (DOI)
Available from: 2008-09-12 Created: 2008-09-12 Last updated: 2014-10-28Bibliographically approved
2. Time stress, predation risk and diurnal-nocturnal foraging trade-offs in larval prey.
Open this publication in new window or tab >>Time stress, predation risk and diurnal-nocturnal foraging trade-offs in larval prey.
2008 (English)In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 62, no 10, 1655-1663 p.Article in journal (Refereed) Published
Abstract [en]

Insect larvae increase in size with several orders of magnitude throughout development making them more conspicuous to visually hunting predators. This change in predation pressure is likely to impose selection on larval anti-predator behaviour and since the risk of detection is likely to decrease in darkness, the night may offer safer foraging opportunities to large individuals. However, forsaking day foraging reduces development rate and could be extra costly if prey are subjected to seasonal time stress. Here we test if size-dependent risk and time constraints on feeding affect the foraging–predation risk trade-off expressed by the use of the diurnal–nocturnal period. We exposed larvae of one seasonal and one non-seasonal butterfly to different levels of seasonal time stress and time for diurnal–nocturnal feeding by rearing them in two photoperiods. In both species, diurnal foraging ceased at large sizes while nocturnal foraging remained constant or increased, thus larvae showed ontogenetic shifts in behaviour. Short night lengths forced small individuals to take higher risks and forage more during daytime, postponing the shift to strict night foraging to later on in development. In the non-seasonal species, seasonal time stress had a small effect on development and the diurnal–nocturnal foraging mode. In contrast, in the seasonal species, time for pupation and the timing of the foraging shift were strongly affected. We argue that a large part of the observed variation in larval diurnal–nocturnal activity and resulting growth rates is explained by changes in the cost/benefit ratio of foraging mediated by size-dependent predation and time stress.

Keyword
Predation risk - Growth rate - Life history theory - Body size - Seasonal constraints
Identifiers
urn:nbn:se:su:diva-24852 (URN)10.1007/s00265-008-0594-4 (DOI)000257912700013 ()
Note
Part of urn:nbn:se:su:diva-7498Available from: 2008-04-24 Created: 2008-04-16 Last updated: 2017-12-13Bibliographically approved
3. What keeps insects small?: Time limitation during oviposition reduces the fecundity benefit of female size in a butterfly.
Open this publication in new window or tab >>What keeps insects small?: Time limitation during oviposition reduces the fecundity benefit of female size in a butterfly.
2007 (English)In: American naturalist, Vol. 169, 768-779 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24853 (URN)000246553900008 ()
Note
Part of urn:nbn:se:su:diva-7498Available from: 2008-04-24 Created: 2008-04-16 Last updated: 2014-10-28Bibliographically approved
4. What limits insect fecundity? Body size- and temperature-dependent egg maturation and oviposition in a butterfly
Open this publication in new window or tab >>What limits insect fecundity? Body size- and temperature-dependent egg maturation and oviposition in a butterfly
2008 (English)In: Functional Ecology, ISSN 0269-8463, Vol. 22, no 3, 523-529 p.Article in journal (Refereed) Published
Abstract [en]

1. Large female insects usually have high potential fecundity. Therefore selection should favour an increase in body size given that these females get opportunities to realize their potential advantage by maturing and laying more eggs. However, ectotherm physiology is strongly temperature-dependent, and activities are carried out sufficiently only within certain temperature ranges. Thus it remains unclear if the fecundity advantage of a large size is fully realized in natural environments, where thermal conditions are limiting.

2. Insect fecundity might be limited by temperature at two levels; first eggs need to mature, and then the female needs time for strategic ovipositing of the egg. Since a female cannot foresee the number of oviposition opportunities that she will encounter on a given day, the optimal rate of egg maturation will be governed by trade-offs associated with egg- and time-limited oviposition. As females of different sizes will have different amounts of body reserves, size-dependent allocation trade-offs between the mother's condition and her egg production might be expected.

3. In the temperate butterfly Pararge aegeria, the time and temperature dependence of oviposition and egg maturation, and the interrelatedness of these two processes were investigated in a series of laboratory experiments, allowing a decoupling of the time budgets for the respective processes.

4. The results show that realized fecundity of this species can be limited by both the temperature dependence of egg maturation and oviposition under certain thermal regimes. Furthermore, rates of oviposition and egg maturation seemed to have regulatory effects upon each other. Early reproductive output was correlated with short life span, indicating a cost of reproduction. Finally, large females matured more eggs than small females when deprived of oviposition opportunities. Thus, the optimal allocation of resources to egg production seems dependent on female size.

5. This study highlights the complexity of processes underlying rates of egg maturation and oviposition in ectotherms under natural conditions. We further discuss the importance of temperature variation for egg- vs. time-limited fecundity and the consequences for the evolution of female body size in insects.

Keyword
body size, ectotherms, egg maturation, fecundity, Lepidoptera, life-history theory, ovigenesis, oviposition
National Category
Ecology Ecology
Identifiers
urn:nbn:se:su:diva-14394 (URN)doi:10.1111/j.1365-2435.2008.01392.x (DOI)000255940400017 ()
Available from: 2008-09-12 Created: 2008-09-12 Last updated: 2014-10-28Bibliographically approved
5. Large females lose more: sexual conflicts reduce female fecundity and directional selection on body size in the butterfly Leptidea sinapis.
Open this publication in new window or tab >>Large females lose more: sexual conflicts reduce female fecundity and directional selection on body size in the butterfly Leptidea sinapis.
(English)Manuscript (Other (popular science, discussion, etc.))
Identifiers
urn:nbn:se:su:diva-24855 (URN)
Note
Part of urn:nbn:se:su:diva-7498Available from: 2008-04-24 Created: 2008-04-16 Last updated: 2014-10-28Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Berger, David
By organisation
Department of Zoology
Biological Sciences

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 288 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf