2018
 

Evolution of complex asexual reproductive strategies in jellyfish

År: 2018

Evolution of complex asexual reproductive strategies in jellyfish

Schnedler-Meyer, N. A., Pigolotti, S. & Mariani, P. 1 Jul 2018 In : American Naturalist.

Publication: Research - peer-reviewJournal article – Annual report year: 2018

Many living organisms in terrestrial and aquatic ecosystems rely on multiple reproductive strategies to reduce the risk of extinction in variable environments. Examples are provided by the polyp stage of several bloom-forming jellyfish species, which can reproduce asexually using different budding strategies. These strategies broadly fall into three categories: (1) fast localized reproduction, (2) dormant cysts, or (3) motile and dispersing buds. Similar functional strategies are also present in other groups of species. However, mechanisms leading to the evolution of this rich reproductive diversity are yet to be clarified. Here we model how risk of local population extinction and differential fitness of alternative modes of asexual reproduction could drive the evolution of multiple reproductive modes as seen in jellyfish polyps. Depending on environmental parameters, we find that evolution leads to a unique evolutionarily stable strategy, wherein multiple reproductive strategies generally coexist. As the extinction risk increases, this strategy shifts from a pure budding mode to a dual strategy and finally to one characterized by allocation into all three modes. We identify relative fitness-dependent thresholds in extinction risk where these transitions can occur and discuss our predictions in light of observations on polyp reproduction in laboratory and natural systems.

Original languageEnglish
JournalAmerican Naturalist
ISSN0003-0147
DOIs
StateAccepted/In press - 1 Jul 2018

 

Spatio-temporal pattern formation in predator-prey systems with fitness taxis

År: 2018

Spatio-temporal pattern formation in predator-prey systems with fitness taxis

Heilmann, I. T., Thygesen, U. H. & Sørensen, M. P. 1 May 2018 In : Ecological Complexity. 34, p. 44-57

Publication: Research - peer-reviewJournal article – Annual report year: 2018

We pose a spatial predator–prey model in which the movement of animals is not purely diffusive, but also contains a drift term in the direction of higher specific growth rates. We refer to this as fitness taxis. We conduct a linear stability analysis of the resulting coupled reaction–advection–diffusion equations and derive conditions under which spatial patterns form. We find that for some parameters the problem is ill posed and short waves grow with unbounded speeds. To eliminate this, we introduce spatial kernels in the model, yielding coupled integro-differential equations, and conduct a similar stability analysis for this system. Through numerical simulation, we find that a variety of patterns can emerge, including stationary spatial patterns, standing and travelling waves, and seemingly chaotic spatio-temporal patterns. We argue that fitness taxis represents a simple and generic extension of diffusive motion, is ecologically plausible, and provides an alternative mechanism for formation of patterns in spatially explicit ecosystem models, with emphasis on non-stationary spatio-temporal dynamics.

Original languageEnglish
JournalEcological Complexity
Volume34
Pages (from-to)44-57
ISSN1476-945X
DOIs
StatePublished - 1 May 2018

 

Routes and survival of anadromous brown trout Salmo trutta L. post-smolts during early marine migration through a Danish fjord system

År: 2018

We examined the survival and progression rates of 101 anadromous brown trout Salmo trutta L. post-smolts from two Danish river systems, Karup and Simested, with acoustic telemetry as they migrated through a large Danish fjord system (the Limfjord). No fish were documented to residualize permanently within the fjord, and the minimum survival in the fjord was low (26%) while the mortality per km of migrated linear distance (0.8% km−1) was similar to that found in adjacent and smaller Danish fjords. Survival was positively correlated with length (P = 0.003) but not with condition and river of origin. The fjord has an eastern outlet into the Kattegat and a western outlet into the North Sea, but the western outlet did not exist until 1825. No fish left the fjord in the western direction in the study and all surviving fish (n = 20) left the fjord in the eastern direction. The results suggest that fish from rivers Karup and Simested may have over time become adapted for leaving the Limfjord in the eastern direction and that predation rates and environmental characteristics of the fjord are more important for the fjord's ability to function as a suitable growth habitat for post-smolts than size and the availability of food within it.
Original languageEnglish
JournalEstuarine, Coastal and Shelf Science
ISSN0272-7714
DOIs
StateAccepted/In press - 2018

 

Salinity reduction benefits European eel larvae: Insights at the morphological and molecular level

År: 2018

Salinity reduction benefits European eel larvae: Insights at the morphological and molecular level

Politis, S. N., Mazurais, D., Servili, A., Zambonino‐Infante, J. L., Miest, J., Tomkiewicz, J. & Butts, I. A. E. 2018 In : PLoS ONE.

Publication: Research - peer-reviewJournal article – Annual report year: 2018

European eel (Anguilla anguilla) is a euryhaline species, that has adapted to cope with both, hyper- and hypo-osmotic environments. This study investigates the effect of salinity, from a morphological and molecular point of view on European eel larvae reared from 0 to 12 days post hatch (dph). Offspring reared in 36 practical salinity units (psu; control), were compared with larvae reared in six scenarios, where salinity was decreased on 0 or 3 dph and in rates of 1, 2 or 4 psu/day, towards iso-osmotic conditions. Results showed that several genes relating to osmoregulation (nkcc2α, nkcc2β, aqp1dup, aqpe), stress response (hsp70, hsp90), and thyroid metabolism (thrαA, thrαB, thrβB, dio1, dio2, dio3) were differentially expressed throughout larval development, while nkcc1α, nkcc2β, aqp3, aqp1dup, aqpe, hsp90, thrαA and dio3 showed lower expression in response to the salinity reduction. Moreover, larvae were able to keep energy metabolism related gene expression (atp6, cox1) at stable levels, irrespective of the salinity reduction. As such, when reducing salinity, an energy surplus associated to reduced osmoregulation demands and stress (lower nkcc, aqp and hsp expression), likely facilitated the observed increased survival, improved biometry and enhanced growth efficiency. Additionally, the salinity reduction decreased the amount of severe deformities such as spinal curvature and emaciation but also induced an edematous state of the larval heart, resulting in the most balanced mortality/deformity ratio when salinity was decreased on 3 dph and at 2 psu/day. However, the persistency of the pericardial edema and if or how it represents an obstacle in further larval development needs to be further clarified. In conclusion, this study clearly showed that salinity reduction regimes towards iso-osmotic conditions facilitated the European eel pre-leptocephalus development and revealed the existence of highly sensitive and regulated osmoregulation processes at such early life stage of this species
Original languageEnglish
JournalPLoS ONE
ISSN1932-6203
StateAccepted/In press - 2018

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Transgenerational effects of pesticide on vector mosquito Culex pipiens under global warming

År: 2018

Transgenerational effects of pesticide on vector mosquito Culex pipiens under global warming

Tran, T., Janssens, L. & Dinh, K. V. 2018

Publication: ResearchConference abstract for conference – Annual report year: 2018

Original languageEnglish
Publication date2018
StatePublished - 2018
EventSETAC Europe 28th Annual Meeting - Rome, Italy

Conference

ConferenceSETAC Europe 28th Annual Meeting
CountryItaly
CityRome
Period13/05/201817/05/2018

Bibliographical note

Conference: SETAC Europe 28th Annual MeetingAt: Rome, Italy