| 1. |
- Boom, Michiel P., et al.
(författare)
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Postnatal growth rate varies with latitude in range‐expanding geese : The role of plasticity and day length
- 2022
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Ingår i: Journal of Animal Ecology. - : British Ecological Society. - 0021-8790 .- 1365-2656. ; 91:2, s. 417-427
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Tidskriftsartikel (refereegranskat)abstract
- 1. The postnatal growth period is a crucial life stage, with potential lifelong effects on an animal's fitness. How fast animals grow depends on their life-history strategy and rearing environment, and interspecific comparisons generally show higher growth rates at higher latitudes. However, to elucidate the mechanisms behind this gradient in growth rate, intraspecific comparisons are needed. 2. Recently, barnacle geese expanded their Arctic breeding range from the Russian Barents Sea coast southwards, and now also breed along the Baltic and North Sea coasts. Baltic breeders shortened their migration, while barnacle geese breeding along the North Sea stopped migrating entirely.3. We collected cross-sectional data on gosling tarsus length, head length and body mass, and constructed population-specific growth curves to compare growth rates among three populations (Barents Sea, Baltic Sea and North Sea) spanning 17° in latitude.4. Growth rate was faster at higher latitudes, and the gradient resembled the latitudinal gradient previously observed in an interspecific comparison of precocial species. Differences in day length among the three breeding regions could largely explain the observed differences in growth rate. In the Baltic, and especially in the Arctic population, growth rate was slower later in the season, most likely because of the stronger seasonal decline in food quality.5. Our results suggest that differences in postnatal growth rate between the Arctic and temperate populations are mainly a plastic response to local environmental conditions. This plasticity can increase the individuals' ability to cope with annual variation in local conditions, but can also increase the potential to re-distribute and adapt to new breeding environments.
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| 2. |
- Hall, Marcus, et al.
(författare)
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Intra-population variation in reproductive timing covaries with thermal plasticity of offspring performance in perch Perca fluviatilis
- 2021
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons. - 0021-8790 .- 1365-2656.
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Tidskriftsartikel (refereegranskat)abstract
- Life history theory posits that organisms should time their reproduction to coincide with environmental conditions that maximize their fitness. Population-level comparisons have contributed important insights on the adaptive value of reproductive timing and its association to environmental variation. Yet, despite its central role to ecology and evolution, the causes and consequences of variation in reproductive timing among individuals within populations are poorly understood in vertebrates other than birds.Using a combination of observational field studies and a split-brood experiment, we investigated whether differences in breeding time were associated with changes in hatching success, reproductive allocation and reaction norms linking offspring performance to temperature within an anadromous Baltic Sea population of perch Perca fluviatilis.Field observations revealed substantial variation in reproductive timing, with the breeding period lasting almost 2 months and occurring in temperatures ranging from 10 to 21°C. The hatching success of perch decreased as the reproductive season progressed. At the same time, the reproductive allocation strategy changed over the season, late breeders (the offspring of which were introduced into a high resource environment and increased predation pressure) produced more and smaller eggs that resulted in smaller larvae, compared with early breeders.The split-brood experiment in which eggs were incubated in different temperatures (10, 12, 15, 18°C) showed that differences in reproductive timing were associated with a change in the shape of the reaction norm linking offspring performance to water temperature indicative of adaptive phenotypic plasticity, with the offspring of early breeders performing best in low temperatures and the offspring of late breeders performing best in high temperatures.The seasonal changes in reproductive traits and the shape of the thermal performance suggest time-dependent adaptive differences among individuals within the population. Management actions aimed at preserving and restoring variation in the timing of reproductive events will thus likely also influence variation in associated life history traits and thermal performance curves, which could safeguard populations against environmental challenges and changes associated with exploitation and global warming.
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| 3. |
- Tibblin, Petter, et al.
(författare)
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Causes and consequences of repeatability, flexibility and individual fine tuning of of migratory timing in pike
- 2016
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 85:1, s. 136-145
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Tidskriftsartikel (refereegranskat)abstract
- 1. Many organisms undertake migrations between foraging and breeding habitats and while it is assumed that reproductive timing affects fitness, little is known about the degree of individual consistency, and about the causes and consequences of individual variation in migratory timing in organisms other than birds. 2. Here, we report on a 6-year mark-recapture study, including 2048 individuals, of breeding migration in anadromous pike (Esox lucius), an iteroparous top-predatory fish that displays homing behaviour. By repeated sampling across years at a breeding site, we first quantify individual variation both within and between breeding events and then investigate phenotypic correlates and fitness consequences of arrival timing to the breeding site. 3. Our data demonstrate that males arrive before females, that large males arrive later than small males, that the timing of breeding migration varies among years and that individuals are consistent in their timing across years relative to other individuals in the population. 4. Furthermore, data on return rates indicate that arrival time is under stabilizing viability selection, and that individuals who are more flexible in their timing of arrival during the first reproductive years survive longer compared with less flexible individuals. Finally, longitudinal data demonstrate that individuals consistently fine-tune their arrival timing across years, showing that the timing of arrival to breeding sites is influenced by experience. 5. These findings represent rare evidence of how between-and within-individual variations in migratory timing across breeding events are correlated with phenotypic and fitness traits in an ecologically important keystone species. Our results emphasize the importance of considering variation in migratory timing both between and within individuals in studies investigating the fitness consequences of migratory behaviour and have implications for future management.
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| 4. |
- Nilsson, Jonas, et al.
(författare)
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Predator-prey role reversal may impair the recovery of declining pike populations
- 2019
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons. - 0021-8790 .- 1365-2656. ; 88:6, s. 927-939
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Tidskriftsartikel (refereegranskat)abstract
- Many fish populations have experienced declines in recent decades due to anthropogenic disturbances, such as overfishing and habitat exploitation. Despite management actions, many populations show a limited capacity to recover. This may be attributed to reversal of predator-prey roles, yet empirical evidence to that effect remains scarce. Here, we combine field and laboratory studies to investigate the interaction between pike (Esox lucius), a large keystone top predatory fish, and the small-bodied mesopredatory threespine stickleback (Gasterosteus aculeatus) in the Baltic Sea where pike populations have declined. Our data suggest that stickleback predation on pike larvae depletes a large proportion of the recruitment and influences the size distribution through size-selective predation, which is corroborated by a gape-limitation experiment and diet analysis of wild-captured sticklebacks. The effects of stickleback predation are present across several populations and years, and our data suggest that early arrival of sticklebacks has stronger effects on juvenile pike survival. Finally, we use data on pike gape-limitation and the size distribution of sticklebacks to illustrate the process of role reversal. These findings suggest that mesopredator behaviour can reduce recruitment of a top predator species and impair the capacity of populations to recover. This emphasizes predator-prey role reversal as an important ecological and evolutionary driver that influences the outcome of restoration and management actions.
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| 5. |
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| 6. |
- Forslund, Pär, et al.
(författare)
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Age-related reproductive success in the barnacle goose
- 1992
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Ingår i: Journal of Animal Ecology. - : British Ecological Society. - 0021-8790 .- 1365-2656. ; 61, s. 195-204
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Tidskriftsartikel (refereegranskat)abstract
- 1. We studied age-related reproductive success in a recently established breeding colony of barnacle goose Branta leucopsis on the island of Gotland, Sweden.2. Associations of age and breeding experience with several reproductive parameters were investigated by comparing the success of individuals of 2, 3, 4 and >=5 years of age. Also, we measured the within-individual changes in reproductive parameters as the individuals grew older.3. Associations between survival and reproductive success were investigated by comparing the reproductive success of 2, 3 and 4-year-old birds that returned or did not return, respectively, in the subsequent breeding season.4. The reproductive success increased up to an age of 4-5 years. Thus, clutch size, number of hatched young and number of fledged young increased, and hatching date was advanced with increasing age. This was due to the fact that individuals increased in reproductive success as they grew older.5. A possibly higher probability of survival among individuals that perform well in reproduction could not explain the higher reproductive success in older age-classes as compared to young age-classes of geese, because there were no associations between survival and reproductive success, and very few individuals did actually disappear between any two breeding seasons.6. Path analysis suggested age effects only at earlier stages of reproduction, i. e. timing of breeding and clutch size. These characters, in turn, were associated with number of fledged young. These findings were further supported by measurements of hatching success and rearing success, which did not seem to increase with age.7. Increased breeding experience was associated with early hatching date and larger clutch size in males, and with larger clutch size in females. This was concluded from path analysis and from comparisons of individuals of the same age but with different breeding experience.8. The increase in reproductive success with age in the barnacle goose is probably a result of age-related skills in individuals and the direct effects of these skills on reproductive success, but possibly also because of increased reproductive effort with age owing to these age-related skills.
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| 7. |
- Forsman, Anders
(författare)
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Variation in sexual size dimorphism and maximum body size among adder populations: effects of prey size
- 1991
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Ingår i: Journal of Animal Ecology. - : JSTOR. - 0021-8790 .- 1365-2656. ; 60:1, s. 253-267
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Tidskriftsartikel (refereegranskat)abstract
- (1) Geographic variation in maximum body size of male and female adders, Vipera berus, was documented over one mainland locality and six groups of islands in the Baltic Sea. Males varied more in body size among localities than females, although not significantly so. (2) Geographic variation in prey (field vole, Microtus agrestis) body size explained 68% and 40% of the variation in maximum body size of male and female adders, respectively. Body size of adders increased with body size of prey. (3) Adders were smaller on islands where there were three prey species than where there were two. It is suggested that selection for fasting endurance where there are few prey species and a high risk of starvation may have produced this pattern. (4) Growth rates of individual adders were faster where mean field vole body weight was large (47 g) than where it was small (26 g). Maximum body size of adders was large where growth rate was fast and vice versa. (5) Female adders were larger than males at all localities. Females also had faster growth rates than males. (6) The degree of sexual size dimorphism of adders varied among localities and was negatively correlated with size of males. There was no relationship between sexual dimorphism and size of females. (7) There was no significant relationship between sexual size dimorphism of adders and mean body size of field voles. Nor was there any relationship between sexual dimorphism and number of prey species or size distribution of field voles. (8) I argue that optimal body size for survival is locally determined by prey availability and size of prey items. However, due to the fecundity advantage of large size in females, female adders deviate from the optimum size for survival, and more so when this optimum size is small. Thus, local variation in properties of the food resource, e.g. prey size, can give rise to variation in sexual size dimorphism.
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| 8. |
- Larsson, Kjell, et al.
(författare)
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Population dynamics of the barnacle goose Branta leucopsis in the Baltic area : density-dependent effects on reproduction
- 1994
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Ingår i: Journal of Animal Ecology. - : British Ecological Society. - 0021-8790 .- 1365-2656. ; 63:4, s. 954-962
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Tidskriftsartikel (refereegranskat)abstract
- 1. The three largest breeding colonies of barnacle geese Branta leucopsis in the Baltic area were studied from their natural establishments in 1971, 1982 and 1987, respectively, to 1993. The number of breeding pairs increased from one pair in 1971 to 1550, 225 and 150 pairs in the largest, second largest, and third largest colonies, respectively, in 1993. 2. Data on clutch size and number of hatched and fledged young were collected from the beginning or the middle of the 1980s. In the largest colony most data on reproductive success were obtained from observations of individually marked geese. 3. Mean clutch size differed among years and colonies. However, there was no trend for decreasing mean clutch size with increasing density in any of the colonies. Hatching success did not decrease with increasing density in the largest colony. 4. The production of fledged young per breeding pair declined drastically in the largest colony as numbers of breeding pairs rose. This decline was mainly caused by an increasing proportion of the breeding pairs failing to produce any fledged young at all. 5. The relative contribution of the smaller colonies to the total production of fledged young in the Baltic area increased considerably over the study years. In 1993, colony 2 hosted only about 13% of the number of breeding pairs in colonies 1 and 2 combined, but it produced about 38% of the fledged young. 6. Our results point out the need to study populations of colonially nesting geese on a colony by colony basis in order to detect density-dependent effects on reproduction.
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| 9. |
- van der Jeugd, Henk P, et al.
(författare)
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Pre-Breeding Survival of Barnacle Geese Branta leucopsis in Relation to Fledgling Characteristics
- 1998
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Ingår i: Journal of Animal Ecology. - : British Ecological Society. - 0021-8790 .- 1365-2656. ; 67:6, s. 953-966
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Tidskriftsartikel (refereegranskat)abstract
- 1. Pre-breeding survival, i.e. survival from fledging up to the third winter, of barnacle geese (Branta leucopsis) was analysed by using more than 45 000 resightings of 1302 individually marked birds. Since observations from the wintering areas only were used, the survival estimates obtained were not confounded by natal dispersal. 2. Post-fledging survival, i.e. survival from fledging to the start of the first winter, differed significantly among the 10 cohorts analysed. These differences were related to the mean body weight and mean tarsus length of cohorts just before fledging. In further analyses, when data from all cohorts were combined, body weight and tarsus length of individuals just before fledging were found to be positively related to Post-fledging survival. 3. Post-fledging survival rates were, on average, lower than survival rates after the first winter. This age effect was largest in cohorts with low mean body weight at capture and was absent in cohorts with high mean body weight at capture. 4. The age effect on survival could only partly be explained by individuals with low body weight having lower survival and successively disappearing from the cohort. It was therefore concluded that other factors must have contributed to the age effect as well. 5. It is hypothesized that lightweight birds are more vulnerable to, for example, diseases, parasites and predation during the first months of their life. Once they have survived this critical period, the effects of characters related to low body weight at capture seem to disappear. 6. Body size of juveniles just before fledging has previously been found to be greatly affected by weather factors and the availability of high quality food during the growth period. Hence, a considerable part of the observed variation in Pre-breeding survival appears to be outside the individual's control.
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