| 1. |
- Berger, David, et al.
(författare)
-
Intraspecific variation in body size and the rate of reproduction in female insects- adaptive allometry or biophysical constraint?
- 2012
-
Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 81:6, s. 1244-1258
-
Tidskriftsartikel (refereegranskat)abstract
- 1. A high rate of reproduction may be costly if ecological factors limit immediate reproductive output as a fast metabolism compromises own future survival. Individuals with more reserves need more time and opportunity to realize their reproductive potential. Theory therefore predicts that the reproductive rate, defined as the investment in early reproduction in proportion to total potential, should decrease with body size within species. 2. However, metabolic constraints on body size- and temperature-dependent biological rates may impede biophysical adaptation. Furthermore, the sequential manner resources that are allocated to somatic vs. reproductive tissue during ontogeny may, when juveniles develop in unpredictable environments, further contribute to non-adaptive variation in adult reproductive rates. 3. With a model on female egg laying in insects, we demonstrate how variation in body reserves is predicted to affect reproductive rate under different ecological scenarios. Small females always have higher reproductive rates but shorter lifespans. However, incorporation of female host selectivity leads to more similar reproductive rates among female size classes, and oviposition behaviour is predicted to co-evolve with reproductive rate, resulting in small females being more selective in their choice and gaining relatively more from it. 4. We fed simulations with data on the butterfly Pararge aegeria to compare model predictions with reproductive rates of wild butterflies. However, simulated reproductive allometry was a poor predictor of that observed. Instead, reproductive rates were better explained as a product of metabolic constraints on rates of egg maturation, and an empirically derived positive allometry between reproductive potential and size. However, fitness is insensitive to moderate deviations in reproductive rate when oviposition behaviour is allowed to co-evolve in the simulations, suggesting that behavioural compensation may mitigate putative metabolic and developmental constraints. 5. More work is needed to understand how physiology and development together with compensatory behaviours interact in shaping reproductive allometry. Empirical studies should evaluate adaptive hypotheses against proper null hypotheses, including prediction from metabolic theory, preferentially by studying reproductive physiology in combination with behaviour. Conversely, inferences of constraint explanations on reproductive rates must take into consideration that adaptive scenarios may predict similar allometric exponents.
|
|
| 2. |
- Friberg, Magne, et al.
(författare)
-
Habitat choice precedes host plant choice - niche separation in a species pair of a generalist and a specialist butterfly
- 2008
-
Ingår i: Oikos. - Lund : Department of Ecology, Lund university. ; 117:9, s. 1337-1344
-
Tidskriftsartikel (refereegranskat)abstract
- The sister species Leptidea reali and L. sinapis have partitioned their niches differently in different parts of their sympatric distribution. In Spain and France L. sinapis is a widespread generalist whereas L. reali is specialized on high altitude open areas. Interestingly, the reverse is true in Ireland and the Czech Republic where L. reali is widespread and L. sinapis specialized on meadows. In Sweden, L. reali is a habitat specialist confined to meadows, whereas L. sinapis is a habitat generalist also inhabiting forests. Ultimately, the geographic mosaic of niche separation is the result of local processes in each contact zone or a secondary effect of the host plant distribution, if L. sinapis and L. reali prefer different legume host plants. Hence, in Sweden L. sinapis might utilize the forest habitat either due to a wider habitat preference or due to a wider host plant preference than L. reali. Studies of wild butterflies showed that L. sinapis laid 26% of their eggs on forest-associated legumes compared to 6% in L. reali, although laboratory experiments showed that both species had virtually identical host plant preferences strongly preferring the meadow-associated legume Lathyrus pratensis. Furthermore, flight duration tests in a variety of temperatures demonstrated a between-species difference; L. sinapis females reached their flight optimum at a lower temperature than L. reali females. The lower L. sinapis flight temperature optimum is most probably a secondary effect due to habitat-specific selection, and therefore a consequence rather than the cause of the habitat partitioning. The finding that habitat choice precedes host plant choice suggests that the European geographic mosaic of niche separation, with L. sinapis and L. reali shifting habitat specialist/generalist roles, is not caused by rigid between-species differences in a related niche parameter, but instead is a result of local processes within each secondary contact zone.
|
|
| 3. |
- Karlsson, Bengt, et al.
(författare)
-
Test of a developmental trade-off in a polyphenic butterfly: direct development favours reproductive output
- 2008
-
Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 22:1, s. 121-126
-
Tidskriftsartikel (refereegranskat)abstract
- 1.Evolutionary theory predicts that resource allocation decisions taken during development are adjusted to an organism's life-history. These decisions may have irreversible effects on body design and strong fitness consequences. Holometabolous insects that have a long expected life span typically postpone reproduction, and so are expected to allocate resources for somatic maintenance prior to investing in reproduction. In contrast, insects that have a short expected life span are expected to allocate relatively less to soma and more to reproduction. In support of this theory, an earlier investigation of resources allocated to soma vs. reproductive reserves in the comma butterfly, Polygonia c-album, revealed that short-lived females indeed allocate more resources to reproductive reserves as compared to longer lived females that hibernate before reproduction suggesting that short-lived females should have higher fecundity. 2. Here we test this prediction, using the comma butterfly as our study organism. Depending on daylength and temperature this butterfly produces one of two morphs: (i) a light summer morph that reproduces directly after adult eclosion and has a short expected life span of a couple of weeks; or (ii) a darker winter morph that normally lives for 8–9 months before the onset of reproduction. Our test is based on experimental manipulation that allowed us to induce reproduction without prior hibernation in winter morph comma butterflies, and comparing lifetime fecundity among three groups: (i) directly reproducing summer morph commas; (ii) directly reproducing winter morph commas; and (iii) winter morph commas reproducing after overwintering. This protocol allowed us to tease apart trade-offs during development and the hibernation period. 3. The results showed that the short-lived summer morph had a substantially higher fecundity (total number of eggs = 586 ± 19, mean ± SE) than the winter morph females manipulated to reproduce without hibernation (total number of eggs = 334 ± 42). We argue that this is a consequence of a resource allocation trade-off during early development observed in this species; females with a short expected life as adults allocate relatively more of their resources to reproductive parts and thereby reach a higher reproductive output compared to females predisposed for a long adult life. 4. There was no significant difference in lifetime fecundity between winter morph females that did, or did not, hibernate before reproduction. This suggests that the cost of hibernation per se is small and hence corroborates our conclusion that the life-history implemented trade-off made during early development underlies the lower reproductive output of the winter morph butterflies.
|
|
| 4. |
- Navarro-Cano, Jose A., et al.
(författare)
-
Climate change, phenology, and butterfly host plant utilization
- 2015
-
Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44:S!, s. S78-S88
-
Tidskriftsartikel (refereegranskat)abstract
- Knowledge of how species interactions are influenced by climate warming is paramount to understand current biodiversity changes. We review phenological changes of Swedish butterflies during the latest decades and explore potential climate effects on butterfly-host plant interactions using the Orange tip butterfly Anthocharis cardamines and its host plants as a model system. This butterfly has advanced its appearance dates substantially, and its mean flight date shows a positive correlation with latitude. We show that there is a large latitudinal variation in host use and that butterfly populations select plant individuals based on their flowering phenology. We conclude that A. cardamines is a phenological specialist but a host species generalist. This implies that thermal plasticity for spring development influences host utilization of the butterfly through effects on the phenological matching with its host plants. However, the host utilization strategy of A. cardamines appears to render it resilient to relatively large variation in climate.
|
|
| 5. |
- Stjernholm, Fredrik, 1973-
(författare)
-
Allocation of body resources to reproduction in butterflies
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The life-history of an organism can be studied and understood in terms of acquisition and expenditure of resources. In butterflies, the use of resources for reproduction has been the focus of much research due to the possibility to easily quantify both the input of resources from different sources over the life-cycle as well as the partitioning of these resources to reproduction. In the first part of my thesis we studied how the pattern of partitioning of resources between somatic tissue, such as muscles, wings and exoskeleton, and storage of resources for reproductive purposes during metamorphosis affects reproduction. Theory predicts that reproduction should be strongly dependent on the relative investments in soma and reproductive reserves, but this has generally proven difficult to show empirically. Butterflies are eminently suited for testing this prediction, and our results show that fecundity of female comma butterflies (Polygonia c-album) is strongly influenced by allocation priorities. One aspect of resource use that has not attracted attention until recently is the possibility that butterflies during the reproductive stage can break down flight muscles in the thorax and use muscle nutrients for reproduction. Since butterflies are generally resource limited this could alleviate the costs resulting from somatic investment found in paper I. Through a series of studies we show that thorax mass and nitrogen content decreases over the adult lifespan in a manner consistent with the hypothesis that thorax resources are used for reproduction. In order to determine if these resources could actually come from the flight muscles, something that is known to occur in other insects, the reduction in flight muscle size over the lifespan was studied in the green-veined white butterfly (Pieris napi). The results showed that flight muscle size decreased with on average 75% in long-lived females, suggesting that breakdown of flight muscles could indeed influence reproduction. Taken together, the work in this thesis shows that resource allocation during metamorphosis strongly influences the reproductive potential, but that butterflies can overcome some of the costs of somatic investment by reallocating resources from thoracic tissue to reproduction.
|
|
