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| 2. |
- Beckerman, A, et al.
(author)
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Population dynamic consequences of delayed life-history effects
- 2002
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In: Trends in Ecology & Evolution. - 1872-8383. ; 17:6, s. 263-269
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Research review (peer-reviewed)abstract
- Evidence from wildlife and human populations indicates that conditions during early development can have marked effects on the subsequent performance of individuals and cohorts. Likewise, the effects of maternal and, more generally, parental environments can be transferred among individuals between generations. These delayed life-history effects are found consistently and suggestions have been made that they can be one source of both variability and of delayed density dependence in population dynamics. Assessments of several different time series indicate that population variability and delayed density dependence are common and that understanding the mechanisms giving rise to them is crucial for the interpretation and application of such models to basic and applied research. Therefore, it is necessary to assess the different ways in which history in the life history might give rise to variability and delayed density dependence in population dynamics. Here, we build on recent appraisals of the pervasive influence of past environmental conditions on current and future fitness and link the details of these life-history studies to classic features of population dynamics.
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| 3. |
- Björklund, Mats, et al.
(author)
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Quantitative Trait Evolution and Environmental Change
- 2009
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In: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 4:2, s. e4521-
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Journal article (peer-reviewed)abstract
- Background: Given the recent changes in climate, there is an urgent need to understand the evolutionary ability of populations to respond to these changes. Methodology/Principal Findings: We performed individual-based simulations with different shapes of the fitness curve, different heritabilities, different levels of density compensation, and different autocorrelation of environmental noise imposed on an environmental trend to study the ability of a population to adapt to changing conditions. The main finding is that when there is a positive autocorrelation of environmental noise, the outcome of the evolutionary process is much more unpredictable compared to when the noise has no autocorrelation. In addition, we found that strong selection resulted in a higher load, and more extinctions, and that this was most pronounced when heritability was low. The level of density-compensation was important in determining the variance in load when there was strong selection, and when genetic variance was lower when the level of density-compensation was low. Conclusions: The strong effect of the details of the environmental fluctuations makes predictions concerning the evolutionary future of populations very hard to make. In addition, to be able to make good predictions we need information on heritability, fitness functions and levels of density compensation. The results strongly suggest that patterns of environmental noise must be incorporated in future models of environmental change, such as global warming.
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| 4. |
- Härdling, Roger, et al.
(author)
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Conflict of interest between sexes over cooperation: a supergame on egg carrying and mating in a coreid bug
- 2001
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In: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 12:6, s. 659-665
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Journal article (peer-reviewed)abstract
- In the golden egg bug (Phyllomorpha laciniata Vill. Heteroptera: Coreidae) females lay eggs on the backs of conspecifics, often on courting males. Although the bugs do not provide care to the eggs, this decreases the risk of egg predation. As an effect males carry many eggs which are not their own. The male and female interests are in conflict; females need to find an oviposition site, and male fitness depends on the obtained number of matings. By using a very rare modeling approach, a supergame where the individuals actions change payoffs over time, we show that combinations of reciprocating strategies where males obtain a mating in return for a carried egg can be stable. The value of the mating, to males, is more important than the relatedness to the eggs in gaining their cooperation in carrying eggs. Females may also take advantage of the males without reciprocating. This is especially likely if the probability of future meeting is high and the value of a mating is high for the male. We relate our results to our own data from empirical studies and experiments on the species. In the light of the results we discuss the behavior of the bugs in relation to nuptial gifts. We also discuss the general applicability of the supergame approach.
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| 5. |
- Härdling, Roger, et al.
(author)
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Male brood care without paternity increases mating success
- 2004
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In: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 15:5, s. 715-721
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Journal article (peer-reviewed)abstract
- We investigate under which conditions we can expect the evolution of costly male care for unrelated offspring, when the benefit of such care is in the form of increased mating success. This applies to male helping behavior that cannot be explained as paternal care because the male's own offspring does not benefit from his behavior. Our model shows that caring for others' offspring can be a stable strategy for males, if a male that does not "help" loses mating opportunities, for example if females discriminate against non-helping males as mating partners. This is possible when females are polyandrous. Increasing population density decreases the parameter region where male care is stable. Male care is also more likely to be stable when male mortality rate is higher than that of females. We discuss the results with special reference to the golden egg bug Phyllomorpha laciniata, where females lay eggs on conspecifics, often on males before mating. Males therefore carry mostly unrelated eggs. We investigate how oviposition rate and female mating rate influences when egg carrying is an evolutionary stable strategy. We conclude that in the golden egg bug, male egg carrying could be explained as a form of mating investment.
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| 6. |
- Härdling, Roger, et al.
(author)
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The evolution of repeated mating under sexual conflict
- 2005
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In: Journal of evolutionary biology. - : Wiley. - 1420-9101 .- 1010-061X. ; 18:1, s. 106-115
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Journal article (peer-reviewed)abstract
- In insects, repeated mating by females may have direct effects on female fecundity, fertility, and longevity. In addition, a female's remating rate affects her fitness through mortality costs of male harassment and ecological risks of mating such as predation. We analyse a model where these female fitness factors are put into their life-history context, and traded against each other, while accounting for limitations because of mate availability. We solve analytically for the condition when female multiple mating will evolve. We show that the probability that a female mates with a courting male decreases with increases in population density. The extent of conflict between the sexes thus automatically becomes larger at higher densities. However, because at higher densities females meet males at a higher rate, the resulting ESS female remating rate is independent of population density. The female remating probability is in conflict with male adaptations that increase male mating rate by persuading or forcing females to mate, and also in conflict with male adaptations for protecting the own sperm from being removed by future female mates. We show that the relative importance of these conflicts depends on population density.
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| 7. |
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| 8. |
- Jackson, A L, et al.
(author)
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Consumer-resource matching in a food chain when both predators and prey are free to move
- 2004
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In: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 106:3, s. 445-450
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Journal article (peer-reviewed)abstract
- The classical theory of the ideal free distribution (IFD) predicts that the spatial distribution of consumers should follow the distribution of the resources they depend on. Here, we study consumer-resource matching in a community context. Our model for the community is a food chain with three levels. We study whether the primary consumers are able to match resources both under predation risk and in its absence. Both prey and predators have varying degrees of knowledge of the global and local resource distribution. We present two versions of the model. In the "resource maximising" model, the consumers consider the availability of their resource only. In the "balancing" model, individual consumers minimise predation risk per unit of resource that they can gain access to. We show that both models can lead to perfect matching of consumers on resources and predators on consumers, assuming that individuals have full knowledge of the whole environment. However, when the consumers' information and freedom of movement are greater than those of the predators, then the predators generally undermatch the consumers. In the opposite case, we observe overmatching and high consumer movement rates. Furthermore, undermatching of predators on consumers tends to induce overmatching of consumers on resources.
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| 9. |
- Kaitala, A, et al.
(author)
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Is nonparental egg carrying parental care?
- 2001
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In: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 12:3, s. 367-368
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Journal article (peer-reviewed)
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| 10. |
- Pertoldi, Cino, et al.
(author)
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Scaling of the mean and variance of population dynamics under fluctuating regimes
- 2014
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In: Theory in Biosciences. - : Springer Science and Business Media LLC. - 1431-7613 .- 1611-7530. ; 133:3-4, s. 165-173
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Journal article (peer-reviewed)abstract
- Theoretical ecologists have long sought to understand how the persistence of populations depends on the interactions between exogenous (biotic and abiotic) and endogenous (e.g., demographic and genetic) drivers of population dynamics. Recent work focuses on the autocorrelation structure of environmental perturbations and its effects on the persistence of populations. Accurate estimation of extinction times and especially determination of the mechanisms affecting extinction times is important for biodiversity conservation. Here we examine the interaction between environmental fluctuations and the scaling effect of the mean population size with its variance. We investigate how interactions between environmental and demographic stochasticity can affect the mean time to extinction, change optimal patch size dynamics, and how it can alter the often-assumed linear relationship between the census size and the effective population size. The importance of the correlation between environmental and demographic variation depends on the relative importance of the two types of variation. We found the correlation to be important when the two types of variation were approximately equal; however, the importance of the correlation diminishes as one source of variation dominates. The implications of these findings are discussed from a conservation and eco-evolutionary point of view.
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