Résumé
Patterns of size variation in fish are supposed to be generated by growth differences, not by egg or hatchling size variation. However, annual killifish live in temporary ponds with a limited time period available for growth and reproduction. It has therefore been hypothesized that among annual killifish, hatchling size variation should be of large relative importance to generate adaptive adult size variation. Using growth curves of 203 individuals from 18 Austrolebias species raised in a common environment, we demonstrate that hatchling size variation indeed is a main determinant of adult size variation in annual killifish, in agreement with the time constraint hypothesis. Furthermore, we find an increased early growth rate in piscivorous species augmenting their difference in size from small congeneric species. This should be adaptive if size differences determine predation success. Environmental effects of spatial location of the population of origin on hatchling size and growth suggest that the time constraint might be weakened in populations occurring near the Atlantic coast. Our study reveals how extreme environments demand specific life history solutions to achieve adaptive size variation and that there might be scope for local adaptations in growth trajectories.
Auteurs, date et publication :
Auteurs Andrew Helmstetter , Tom JM Van Dooren
Publication : bioRxiv
Date : 2019
Pages : 2019.12.31.891648
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Rapid life-history changes caused by size-selective harvesting are often interpreted as a response to direct harvest selection against a large body size. However, similar trait changes may result from a harvest-induced relaxation of natural selection for a large body size via density-dependent selection. Here, we show evidence of such density-dependent selection favouring large-bodied individuals at high population densities, in replicated pond populations of medaka fish. Harvesting, in contrast, selected medaka directly against large-bodied medaka and, in parallel, decreased medaka population densities. Five years of harvesting were enough for harvested and unharvested medaka populations to inherit the classically-predicted trait differences, whereby harvested medaka grew slower and matured earlier than unharvested medaka. We demonstrate that this life-history divergence was not driven by direct harvest selection for a smaller body size in harvested populations, but by density-dependent natural selection for a larger body size in unharvested populations.
Auteurs, date et publication :
Auteurs Alix Bouffet-Halle , Jacques Mériguet , David Carmignac , Simon Agostini , Alexis Millot , Samuel Perret , Eric Motard , Beatriz Decenciere , Eric Edeline
Publication : bioRxiv
Date : 2020
Pages : 561522
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Meryem Mojtahid , Pauline Depuydt , Aurélia Mouret , Fatine Rihani , Sandrine Le Houedec , Sarah Fiorini , Simon Chollet , Florent Massol , Francis Dohou , Helena L. Filipsson , Wim Boer , Gert-Jan Reichart , Sophie Quinchard , Carole La , Christine Barras
Date : 2022
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Brigitte Vinçon-Leite , Yi Hong , Viet Tran Khac , Denis Plec , Chenlu Li , Philippe Dubois , Mohamed Saad , Bruno J Lemaire , Gabriel Hmimina , Kamel Soudani , others
Date : 2025
Catégorie(s)
#⛔ No DOI found #CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Andrea Bertolo , Marco A. Rodríguez , Gérard Lacroix
Publication : Ecosphere
Date : 2025
Volume : 6
Issue : 11
Pages : art219
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Flowing surface waters (rivers, creeks, streams) are integrators of biological, chemical and physical processes occurring in a catchment and they link catchment land cover from the headwaters to the outlet. The dynamics of human and animal pathogens in catchments have been widely studied in a large variety of contexts allowing the optimization of disease risk reduction. In parallel, there is an emerging awareness that crop pathogens might also be disseminated via surface waters especially when they are used for irrigation. However, there are no studies on the extent to which potential plant pathogens are present - nor about their dynamics - along the full course of a catchment. We do not know if they are confined to regions close to crops or if they are present throughout a catchment. Here we have compared the seasonal dynamics of populations of the Pseudomonas syringae (Psy) and the Soft Rot Pectobacteriaceae (SRP) species complexes along a 270 km stretch of the Durance River from the upstream alpine reaches to the downstream agricultural production areas at the confluence with the Rhone River at Avignon. Among 168 samples collected at 21 sites in fall, winter, spring and summer of 2016 and 2017, Psy strains were detected at all sampling sites and in 156 of the samples at population densities up to 10e5 bacteria/L. In contrast, SRP strains were detected in 98 of the samples, mostly from the southern part of the river, at population densities that did not exceed 3 x 10e4 bacteria/L. Among the aquatic parameters that were characterized at each sampling site (total culturable bacteria, temperature, conductivity, concentrations of dissolved organic carbon (DOC), PO43-, NH4+, NO2- and NO3-), temperature was the only factor that explained a significant amount of the variability in population size for both species complexes. Psy densities decreased with increasing temperature whereas SRP densities increased with increasing temperature. River-borne populations of SRP were composed mainly of Pectobacterium versatile and P. aquaticum that have little known epidemiological importance. Only a few strains of Pectobacterium and Dickeya species reputed for their epidemiological impact were observed. In contrast, Psy populations at all sites were dominated by a genetic lineage of phylogroup 2 known from other studies for its broad host range and its geographic and habitat ubiquity. These results suggest that strains of SRP with pathogenic potential to plants have lower competence for saprophytic survival (in freshwaters) than do potentially pathogenic strains of Psy and that their presence in river water is probably much more dependent on specific vegetative sources than are pathogenic strains of Psy. Nevertheless, their vegetative sources have not yet been identified. We discuss how to incorporate knowledge of the abundance and diversity of these two groups of plant pathogens in river water into a strategy for anticipating risk for disease outbreaks on crops in a catchment.
Auteurs, date et publication :
Auteurs Cindy E. Morris , Christelle Lacroix , Charlotte Chandeysson , Caroline Guilbaud , Cécile Monteil , Sylvain Piry , Emma Rochelle-Newall , Sarah Fiorini , Frédérique Van Gijsegem , Marie-Anne Barny , Odile Berge
Date : 2022
Catégorie(s)
#CNRS #PLANAQUAAuteurs, date et publication :
Auteurs Loïc Harrault , Béatrice Allard , Jacques Mériguet , David Carmignac , Sylvain Huon , Benoit Gauzens , Gérard Lacroix
Publication : Freshwater Biology
Date : 2025
Volume : 59
Issue : 8
Pages : 1695-1709
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs O. Guillaume , A. Coulon , J.-F. Le Galliard , J. Clobert , J. F. Le Galliard , F. Gaill , J. M. Guarini
Date : 2025
Pages : 43-61