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Causes and consequences of egg mass variation between and within blue tit clutches

Nilsson, Jan-Åke LU and Svensson, Erik LU (1993) In Journal of Zoology 230(3). p.469-481
Abstract
Causes of egg‐size variation between and within clutches were studied in clutches of the blue tit (Parus caeruleus L.). We measured the mass of each egg in the laying sequence in unmanipulated clutches, in clutches of parents experimentally supplied with extra food before egg‐laying, and in clutches of parents supplemented with extra food after the start of egg‐laying. Hatchlings were weighed at an age of two days and their mass was found to be positively related to egg mass. No general trend of decreasing or increasing egg mass was found within the laying sequence. Females provided with extra food before egg‐laying laid clutches with significantly less variation in egg mass than did control females. The reason for this was that the... (More)
Causes of egg‐size variation between and within clutches were studied in clutches of the blue tit (Parus caeruleus L.). We measured the mass of each egg in the laying sequence in unmanipulated clutches, in clutches of parents experimentally supplied with extra food before egg‐laying, and in clutches of parents supplemented with extra food after the start of egg‐laying. Hatchlings were weighed at an age of two days and their mass was found to be positively related to egg mass. No general trend of decreasing or increasing egg mass was found within the laying sequence. Females provided with extra food before egg‐laying laid clutches with significantly less variation in egg mass than did control females. The reason for this was that the first‐laid egg of unmanipulated females was lighter than the rest of the eggs in the clutch. This pattern disappeared in clutches of females receiving extra food. Thus, the reduction in egg mass variation among clutches of foodsupplemented females depended on an ability of these females, in contrast to control females, to lay a first egg of the same mass as the rest of the clutch. Eggs laid after the initiation of incubation were significantly heavier than equivalent eggs in those clutches where incubation started after clutch completion. The difference was small, however, and the adaptive significance of the finding is questionable. We argue that intra‐clutch variation in egg mass is connected with greater fitness consequences than in inter‐clutch variation. Furthermore, our results indicate that energetical constraints on the laying female are more important as a cause of the observed intra‐clutch variation in egg mass than are adaptive responses to the environment. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Zoology
volume
230
issue
3
pages
469 - 481
publisher
Wiley-Blackwell
external identifiers
  • scopus:0027843749
ISSN
1469-7998
DOI
10.1111/j.1469-7998.1993.tb02699.x
language
English
LU publication?
yes
id
760fcd83-263a-41a7-a17b-ba26b778471a
date added to LUP
2019-06-10 11:30:02
date last changed
2019-08-16 14:22:51
@article{760fcd83-263a-41a7-a17b-ba26b778471a,
  abstract     = {Causes of egg‐size variation between and within clutches were studied in clutches of the blue tit (Parus caeruleus L.). We measured the mass of each egg in the laying sequence in unmanipulated clutches, in clutches of parents experimentally supplied with extra food before egg‐laying, and in clutches of parents supplemented with extra food after the start of egg‐laying. Hatchlings were weighed at an age of two days and their mass was found to be positively related to egg mass. No general trend of decreasing or increasing egg mass was found within the laying sequence. Females provided with extra food before egg‐laying laid clutches with significantly less variation in egg mass than did control females. The reason for this was that the first‐laid egg of unmanipulated females was lighter than the rest of the eggs in the clutch. This pattern disappeared in clutches of females receiving extra food. Thus, the reduction in egg mass variation among clutches of foodsupplemented females depended on an ability of these females, in contrast to control females, to lay a first egg of the same mass as the rest of the clutch. Eggs laid after the initiation of incubation were significantly heavier than equivalent eggs in those clutches where incubation started after clutch completion. The difference was small, however, and the adaptive significance of the finding is questionable. We argue that intra‐clutch variation in egg mass is connected with greater fitness consequences than in inter‐clutch variation. Furthermore, our results indicate that energetical constraints on the laying female are more important as a cause of the observed intra‐clutch variation in egg mass than are adaptive responses to the environment.},
  author       = {Nilsson, Jan-Åke and Svensson, Erik},
  issn         = {1469-7998},
  language     = {eng},
  number       = {3},
  pages        = {469--481},
  publisher    = {Wiley-Blackwell},
  series       = {Journal of Zoology},
  title        = {Causes and consequences of egg mass variation between and within blue tit clutches},
  url          = {http://dx.doi.org/10.1111/j.1469-7998.1993.tb02699.x},
  volume       = {230},
  year         = {1993},
}