| 1. |
- de Boer, M. Karin, et al.
(författare)
-
Dispersal restricts local biomass but promotes the recovery of metacommunities after temperature stress
- 2014
-
Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 123:6, s. 762-768
-
Tidskriftsartikel (refereegranskat)abstract
- Landscape connectivity can increase the capacity of communities to maintain their function when environments change by promoting the immigration of species or populations with adapted traits. However, high immigration may also restrict fine tuning of species compositions to local environmental conditions by homogenizing the community. Here we demonstrate that dispersal generates such a tradeoff between maximizing local biomass and the capacity of model periphyton metacommunities to recover after a simulated heat wave. In non-disturbed metacommunities, dispersal decreased the total biomass by preventing differentiation in species composition between the local patches making up the metacommunity. On the contrary, in metacommunities exposed to a realistic summer heat wave, dispersal promoted recovery by increasing the biomass of heat tolerant species in all local patches. Thus, the heat wave reorganized the species composition of the metacommunities and after an initial decrease in total biomass by 38.7%, dispersal fueled a full recovery of biomass in the restructured metacommunities. Although dispersal may decrease equilibrium biomass, our results highlight that connectivity is a key requirement for the response diversity that allows ecological communities to adapt to climate change through species sorting.
|
|
| 2. |
- Lewandowska, Aleksandra M., et al.
(författare)
-
Temperature effects on phytoplankton diversity - The zooplankton link
- 2014
-
Ingår i: Journal of Sea Research. - : Elsevier. - 1385-1101 .- 1873-1414. ; 85, s. 359-364
-
Tidskriftsartikel (refereegranskat)abstract
- Recent climate warming is expected to affect phytoplankton biomass and diversity in marine ecosystems. Temperature can act directly on phytoplankton (e.g. rendering physiological processes) or indirectly due to changes in zooplankton grazing activity. We tested experimentally the impact of increased temperature on natural phytoplankton and zooplankton communities using indoor mesocosms and combined the results from different experimental years applying a meta-analytic approach. We divided our analysis into three bloom phases to define the strength of temperature and zooplankton impacts on phytoplankton in different stages of bloom development. Within the constraints of an experiment, our results suggest that increased temperature and zooplankton grazing have similar effects on phytoplankton diversity, which are most apparent in the post-bloom phase, when zooplankton abundances reach the highest values. Moreover, we observed changes in zooplankton composition in response to warming and initial conditions, which can additionally affect phytoplankton diversity, because changing feeding preferences of zooplankton can affect phytoplankton community structure. We conclude that phytoplankton diversity is indirectly affected by temperature in the post-bloom phase through changing zooplankton composition and grazing activities. Before and during the bloom, however, these effects seem to be overruled by temperature enhanced bottom-up processes such as phytoplankton nutrient uptake.
|
|
| 3. |
- Verhagen, Linda A W, et al.
(författare)
-
Acute and chronic suppression of the central ghrelin signaling system reveals a role in food anticipatory activity.
- 2011
-
Ingår i: European neuropsychopharmacology. - : Elsevier BV. - 1873-7862 .- 0924-977X. ; 21:5, s. 384-392
-
Tidskriftsartikel (refereegranskat)abstract
- Using the rodent activity-based anorexia (ABA) model that mimics clinical features of anorexia nervosa that include food restriction-induced hyperlocomotion, we found that plasma ghrelin levels are highly associated with food anticipatory behaviour, measured by running wheel activity in rats. Furthermore, we showed that ghrelin receptor (GHS-R1A) knockout mice do not anticipate food when exposed to the ABA model, unlike their wild type littermate controls. Likewise, food anticipatory activity in the ABA model was suppressed by a GHS-R1A antagonist administered either by acute central (ICV) injection to rats or by chronic peripheral treatment to mice. Interestingly, the GHS-R1A antagonist did not alter food intake in any of these models. Therefore, we hypothesize that suppression of the central ghrelin signaling system via GHS-R1A provides an interesting therapeutic target to treat hyperactivity in patients suffering from anorexia nervosa.
|
|
