| 1. |
- Dahlberg, C. Johan, 1978-, et al.
(författare)
-
Performance of Forest Bryophytes with Different Geographical Distributions Transplanted across a Topographically Heterogeneous Landscape
- 2014
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:11
-
Tidskriftsartikel (refereegranskat)abstract
- Most species distribution models assume a close link between climatic conditions and species distributions. Yet, we know little about the link between species’ geographical distributions and the sensitivity of performance to local environmental factors. We studied the performance of three bryophyte species transplanted at south- and north-facing slopes in a boreal forest landscape in Sweden. At the same sites, we measured both air and ground temperature. We hypothesized that the two southerly distributed species Eurhynchium angustirete and Herzogiella seligeri perform better on south-facing slopes and in warm conditions, and that the northerly distributed species Barbilophozia lycopodioides perform better on north-facing slopes and in relatively cool conditions. The northern, but not the two southern species, showed the predicted relationship with slope aspect. However, the performance of one of the two southern species was still enhanced by warm temperatures. An important reason for the inconsistent results can be that microclimatic gradients across landscapes are complex and influenced by many climate-forcing factors. Therefore, comparing only north- and south-facing slopes might not capture the complexity of microclimatic gradients. Population growth rates and potential distributions are the integrated results of all vital rates. Still, the study of selected vital rates constitutes an important first step to understand the relationship between population growth rates and geographical distributions and is essential to better predict how climate change influences species distributions.
|
|
| 2. |
- Dahlgren, Johan P., et al.
(författare)
-
Local environment and density-dependent feedbacks determine population growth in a forest herb
- 2014
-
Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 176:4, s. 1023-1032
-
Tidskriftsartikel (refereegranskat)abstract
- Linking spatial variation in environmental factors to variation in demographic rates is essential for a mechanistic understanding of the dynamics of populations. However, we still know relatively little about such links, partly because feedbacks via intraspecific density make them difficult to observe in natural populations. We conducted a detailed field study and investigated simultaneous effects of environmental factors and the intraspecific density of individuals on the demography of the herb Lathyrus vernus. In regression models of vital rates we identified effects associated with spring shade on survival and growth, while density was negatively correlated with these vital rates. Density was also negatively correlated with average individual size in the study plots, which is consistent with self-thinning. In addition, average plant sizes were larger than predicted by density in plots that were less shaded by the tree canopy, indicating an environmentally determined carrying capacity. A size-structured integral projection model based on the vital rate regressions revealed that the identified effects of shade and density were strong enough to produce differences in stable population sizes similar to those observed in the field. The results illustrate how the local environment can determine dynamics of populations and that intraspecific density may have to be more carefully considered in studies of plant demography and population viability analyses of threatened species. We conclude that demographic approaches incorporating information about both density and key environmental factors are powerful tools for understanding the processes that interact to determine population dynamics and abundances.
|
|
| 3. |
- Jones, Owen R., et al.
(författare)
-
Diversity of ageing across the tree of life
- 2014
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 505:7482, s. 169-
-
Tidskriftsartikel (refereegranskat)abstract
- Evolution drives, and is driven by, demography. A genotype moulds its phenotype's age patterns of mortality and fertility in an environment; these two patterns in turn determine the genotype's fitness in that environment. Hence, to understand the evolution of ageing, age patterns of mortality and reproduction need to be compared for species across the tree of life. However, few studies have done so and only for a limited range of taxa. Here we contrast standardized patterns over age for 11 mammals, 12 other vertebrates, 10 invertebrates, 12 vascular plants and a green alga. Although it has been predicted that evolution should inevitably lead to increasing mortality and declining fertility with age after maturity, there is great variation among these species, including increasing, constant, decreasing, humped and bowed trajectories for both long-and short-lived species. This diversity challenges theoreticians to develop broader perspectives on the evolution of ageing and empiricists to study the demography of more species.
|
|
| 4. |
- van der Meer, Sascha, et al.
(författare)
-
Differential effects of abandonment on the demography of the grassland perennial Succisa pratensis
- 2014
-
Ingår i: Population Ecology. - : Wiley. - 1438-3896 .- 1438-390X. ; 56:1, s. 151-160
-
Tidskriftsartikel (refereegranskat)abstract
- Abandonment of traditional land-use practices can have strong effects on the abundance of species occurring in agricultural landscapes. However, the precise mechanisms by which individual performance and population dynamics are affected are still poorly understood. To assess how abandonment affects population dynamics of Succisa pratensis we used data from a 4-year field study in both abandoned and traditionally grazed areas in moist and mesic habitats to parameterize integral projection models. Abandoned populations had a lower long-term stochastic population growth rate (lambda (S) = 0.90) than traditionally managed populations (lambda (S) = 1.08), while lambda (S) did not differ between habitat types. The effect of abandonment differed significantly between years and had opposed effects on different vital rates. Individuals in abandoned populations experienced higher mortality rates and lower seedling establishment, but had higher growth rates and produced more flower heads per plant. Population viability analyses, based on a population survey of the whole study area in combination with our demographic models, showed that 32 % of the populations face a high risk of extinction (> 80 %) within 20 years. These results suggest that immediate changes in management are needed to avoid extinctions and further declines in population sizes. Stochastic elasticity analyses and stochastic life table response experiments indicated that management strategies would be most effective if they increase survival of small plants as well as seedling establishment, while maintaining a high seed production. This may be achieved by varying the grazing intensity between years or excluding grazers when plants are flowering.
|
|
| 5. |
- Bisang, Irene, et al.
(författare)
-
Family affiliation, sex ratio and sporophyte frequency in unisexual mosses
- 2014
-
Ingår i: Botanical journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 174:2, s. 163-172
-
Tidskriftsartikel (refereegranskat)abstract
- Patterns of sex expression and sex ratios are key features of the life histories of organisms. Bryophytes are the only haploid-dominant land plants. In contrast with seed plants, more than half of bryophyte species are dioecious, with rare sexual expression and sporophyte formation and a commonly female-biased sex ratio. We asked whether variation in sex expression, sex ratio and sporophyte frequency in ten dioecious pleurocarpous wetland mosses of two different families was best explained by assuming that character states evolved: (1) in ancestors within the respective families or (2) at the species level as a response to recent habitat conditions. Lasso regression shrinkage identified relationships between family membership and sex ratio and sporophyte frequency, whereas environmental conditions were not correlated with any investigated reproductive trait. Sex ratio and sporophyte frequency were correlated with each other. Our results suggest that ancestry is more important than the current environment in explaining reproductive patterns at and above the species level in the studied wetland mosses, and that mechanisms controlling sex ratio and sporophyte frequency are phylogenetically conserved. Obviously, ancestry should be considered in the study of reproductive character state variation in plants.(c) 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174, 163-172.
|
|
| 6. |
- König, Malin A. E., et al.
(författare)
-
Among-Population Variation in Tolerance to Larval Herbivory by Anthocharis cardamines in the Polyploid Herb Cardamine pratensis
- 2014
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:6, s. e99333-
-
Tidskriftsartikel (refereegranskat)abstract
- Plants have two principal defense mechanisms to decrease fitness losses to herbivory: tolerance, the ability to compensate fitness after damage, and resistance, the ability to avoid damage. Variation in intensity of herbivory among populations should result in variation in plant defense levels if tolerance and resistance are associated with costs. Yet little is known about how levels of tolerance are related to resistance and attack intensity in the field, and about the costs of tolerance. In this study, we used information about tolerance and resistance against larval herbivory by the butterfly Anthocharis cardamines under controlled conditions together with information about damage in the field for a large set of populations of the perennial plant Cardamine pratensis. Plant tolerance was estimated in a common garden experiment where plants were subjected to a combination of larval herbivory and clipping. We found no evidence of that the proportion of damage that was caused by larval feeding vs. clipping influenced plant responses. Damage treatments had a negative effect on the three measured fitness components and also resulted in an earlier flowering in the year after the attack. Tolerance was related to attack intensity in the population of origin, i.e. plants from populations with higher attack intensity were more likely to flower in the year following damage. However, we found no evidence of a relationship between tolerance and resistance. These results indicate that herbivory drives the evolution for increased tolerance, and that changes in tolerance are not linked to changes in resistance. We suggest that the simultaneous study of tolerance, attack intensity in the field and resistance constitutes a powerful tool to understand how plant strategies to avoid negative effects of herbivore damage evolve.
|
|
| 7. |
- König, Malin A. E., et al.
(författare)
-
Context-dependent resistance against butterfly herbivory in a polyploid herb
- 2014
-
Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 174:4, s. 1265-1272
-
Tidskriftsartikel (refereegranskat)abstract
- Spatial variation in biotic interactions and natural selection are fundamental parts of natural systems, and can be driven by differences in both trait distributions and the local environmental context of the interaction. Most studies of plant–animal interactions have been performed only in natural settings, making it difficult to disentangle the effects of traits and context. To assess the relative importance of trait differences and environmental context for among-population variation in plant resistance to herbivory, we compared oviposition by the butterfly Anthocharis cardamines on two ploidy types of the herb Cardamine pratensis under experimentally controlled conditions with oviposition in natural populations. Under controlled conditions, plants from octoploid populations were significantly more preferred than plants from tetraploid populations. This difference was largely mediated by differences in flower size. Among natural populations, there was no difference in oviposition rates between the two ploidy types. Our results suggest that differences in oviposition rates among populations of the two cytotypes in the field are caused mainly by differences in environmental context, and that the higher attractiveness of octoploids to herbivores observed under common environmental conditions is balanced by the fact that they occur in habitats which harbor lower densities of butterflies. This illustrates that spatial variation in biotic interactions is the net result of differences in trait distributions of the interacting organisms and differences in environmental context, and that variation in both traits and context are important in understanding species interactions.
|
|
| 8. |
- Posledovich, Diana, et al.
(författare)
-
Latitudinal variation in thermal reaction norms of post-winter pupal development in two butterflies differing in phenological specialization
- 2014
-
Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 113:4, s. 981-991
-
Tidskriftsartikel (refereegranskat)abstract
- Latitudinal clines in thermal reaction norms of development are a common phenomenon in temperate insects. Populations from higher latitudes often develop faster throughout the range of relevant temperatures (i.e countergradient variation) because they must be able to complete their life cycle within a shorter seasonal time window compared to populations at lower latitudes. In the present study, we experimentally demonstrate that two species of butterflies Anthocharis cardamines (L.) and Pieris napi (L.) instead show a cogradient variation in thermal reaction norms of post-winter pupal development so that lower latitude populations develop faster than higher latitude populations. The two species share host plants but differ in the degree of phenological specialization, as well as in the patterns of voltinism. We suggest that the pattern in A. cardamines, a univoltine phenological specialist feeding exclusively on flowers and seedpods, is the result of selection for matching to the phenological pattern of its local host plants. The other species, P. napi, is a phenological generalist feeding on the leaves of the hosts and it shows a latitudinal cline in voltinism. Because the latitudinal pattern in P. napi was an effect of slow development in a fraction of the pupae from the most northern population, we hypothesize that this population may include both bivoltine and univoltine genotypes. Consequently, although the two species both showed cogradient patterns in thermal reaction norms, it appears likely that this was for different reasons.
|
|
| 9. |
- Valdes, Alicia, et al.
(författare)
-
Contrasting effects of different landscape characteristics on population growth of a perennial forest herb
- 2014
-
Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 37:3, s. 230-240
-
Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic changes in landscape structure, such as habitat loss, habitat subdivision and edge increase, can strongly affect the performance of plants, leading to population declines and extinctions. Many studies to date have focused on single characteristics of landscape structure or single life-cycle phases, but they poorly discern the different pathways through which landscape change influences plant population dynamics via different vital rates. In this study, we evaluated the effect of two structural characteristics (habitat quantity and edge length) on vital rates and population growth rates of a perennial forest plant (Primula vulgaris) in a historically managed landscape. Areas with higher amounts of forest habitat had higher population growth rates due to higher recruitment, survival and growth of seedlings, while increased forest edge length was positively associated with population growth rates primarily due to a higher survival of reproductive individuals. Effects were stronger during the first of the two transition intervals studied. The results demonstrate that changes in different landscape structural characteristics may result in opposing effects acting via different vital rates, and highlight the need for integrative analyses to evaluate the effects of rapid landscape transformation on the current and long term plant population dynamics.
|
|
| 10. |
- von Euler, Tove, et al.
(författare)
-
Environmental context influences both the intensity of seed predation and plant demographic sensitivity to attack
- 2014
-
Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 95:2, s. 495-504
-
Tidskriftsartikel (refereegranskat)abstract
- Variation in mutualistic and antagonistic interactions are important sources of variation in population dynamics and natural selection. Environmental heterogeneity can influence the outcome of interactions by affecting the intensity of interactions, but also by affecting the demography of the populations involved. However, little is known about the relative importance of environmental effects on interaction intensities and demographic sensitivity for variation in population growth rates. We investigated how soil depth, soil moisture, soil nutrient composition, and vegetation height influenced the intensity of seed predation as well as host plant demography and sensitivity to seed predation in the perennial herb Primula farinosa. Intensity of seed predation ranged from 0% to 80% of seeds damaged among the 24 study populations and was related to soil moisture in two of four years. The effect of seed predation on plant population growth rate () ranged from negligible to a reduction in by 0.70. Sensitivity of population growth rate to predation explained as much of the variation in the reductions in population growth rate due to seed predation as did predation intensity. Plant population growth rate in the absence of seed predation and sensitivity to predation were negatively related to soil depth and soil moisture. Both intensity of predation and sensitivity to predation were positively correlated with potential population growth rate and, as a result, there was no significant relationship between predation intensity and realized population growth rate. We conclude that in our study system environmental context influences the effects of seed predation on plant fitness and population dynamics in two important ways: through variation in interaction intensity and through sensitivity to the effects of this interaction. Moreover, our results show that a given abiotic factor can influence population growth rate in different directions through effects on potential growth rate, intensity of biotic interactions, and the sensitivity of population growth rate to interactions.
|
|
