Evolutionary change in continuous reaction norms

Abstract Understanding the evolution of reaction norms remains a major challenge in ecology and evolution. Investigating evolutionary divergence in reaction norm shapes between populations and closely related species is one approach to providing insights. Here we use a meta-analytic approach to compare divergence in reaction norms of closely related species or populations of animals and plants across types of traits and environments. We quantified mean-standardized differences in overall trait means (Offset) and reaction norm shape (including both Slope and Curvature). These analyses revealed that differences in shape (Slope and Curvature together) were generally greater than differences in Offset. Additionally, differences in Curvature were generally greater than differences in Slope. The type of taxon contrast (species vs. population), trait, organism, and the type and novelty of environments all contributed to the best-fitting models, especially for Offset, Curvature, and the total differences (Total) between reaction norms. Congeneric species had greater differences in reaction norms than populations, and novel environmental conditions increased the differences in reaction norms between populations or species. These results show that evolutionary divergence of curvature is common and should be considered an important aspect of plasticity, together with slope. Biological details about traits and environments, including cryptic variation expressed in novel environmental conditions, may be critical to understanding how reaction norms evolve in novel and rapidly changing environments

Acceleration performance of individual European sea bass Dicentrarchus labrax measured with a sprint performance chamber: comparison with high-speed cinematography and correlates with ecological performance.

International audienceLocomotor performance can influence the ecological and evolutionary success of a species. For fish, favorable outcomes of predator-prey encounters are often presumably due to robust acceleration ability. Although escape-response or "fast-start" studies utilizing high-speed cinematography are prevalent, little is known about the contribution of relative acceleration performance to ecological or evolutionary success in a species. This dearth of knowledge may be due to the time-consuming nature of analyzing film, which imposes a practical limit on sample sizes. Herein, we present a high-throughput potential alternative for measuring fish acceleration performance using a sprint performance chamber (SPC). The acceleration performance of a large number of juvenile European sea bass (Dicentrarchus labrax) from two populations was analyzed. Animals from both hatchery and natural ontogenies were assessed, and animals of known acceleration ability had their ecological performance measured in a mesocosm environment. Individuals from one population also had their acceleration performance assessed by both high-speed cinematography and an SPC. Acceleration performance measured in an SPC was lower than that measured by classical high-speed video techniques. However, short-term repeatability and interindividual variation of acceleration performance were similar between the two techniques, and the SPC recorded higher sprint swimming velocities. Wild fish were quicker to accelerate in an SPC and had significantly greater accelerations than all groups of hatchery-raised fish. Acceleration performance had no significant effect on ecological performance (as assessed through animal growth and survival in the mesocosms). However, it is worth noting that wild animals did survive predation in the mesocosm better than farmed ones. Moreover, the hatchery-originated fish that survived the mesocosm experiment, when no predators were present, displayed significantly increased acceleration performance during their 6 mo in the mesocosm; this performance was found to be inversely proportional to growth rate

Data from: Local adaptation and the evolution of phenotypic plasticity in Trinidadian guppies (Poecilia reticulata)

Divergent selection pressures across environments can result in phenotypic differentiation that is due to local adaptation, phenotypic plasticity, or both. Trinidadian guppies exhibit local adaptation to the presence or absence of predators, but the degree to which predator-induced plasticity contributes to population differentiation is less clear. We conducted common garden experiments on guppies obtained from two drainages containing populations adapted to high- and low-predation environments. We reared full-sibs from all populations in treatments simulating the presumed ancestral (predator-cues present) and derived (predator-cues absent) conditions and measured water column use, head morphology, and size at maturity. When reared in presence of predator cues, all populations had phenotypes that were typical of a high-predation ecotype. However, when reared in the absence of predator cues, guppies from high- and low-predation regimes differed in head morphology and size at maturity; the qualitative nature of these differences corresponded to those that characterize adaptive phenotypes in high- versus low-predation environments. Thus, divergence in plasticity is due to phenotypic differences between high- and low-predation populations when reared in the absence of predator cues. These results suggest that plasticity might initially play an important role during colonization of novel environments, and then evolve as a by-product of adaptation to the derived environment

Data from: Ecological correlates of the distribution limits of two poeciliid species across a salinity gradient

Identifying the environmental factors responsible for the formation of a species' distribution limit is challenging because organisms interact in complex ways with their environments. However, the use of statistical niche models in combination with the analysis of phenotypic variation along environmental gradients can help to reduce such complexity and identify a subset of candidate factors. In the present study, we used such approaches to describe and identify factors responsible for the parapatric distribution of two closely-related livebearer fish species along a salinity gradient in the lowlands of Trinidad, West Indies. The downstream distribution limits of Poecilia reticulata were strongly correlated with the brackish–freshwater interface. We did not observe significant phenotypic variation in life-history traits for this species when comparing marginal with more central populations, suggesting that abrupt changes in conditions at the brackish–freshwater interface limit its distribution. By contrast, Poecilia picta was present across a wide range of salinities, although it gradually disappeared from upstream freshwater localities. In addition, P. picta populations exhibited an increase in offspring size in localities where they coexist with P. reticulata, suggesting a role for interspecific competition. The parapatric distribution of these two species, suggests that P. reticulata distributions are limited by an abiotic factor (salinity), whereas P. picta is limited by a biotic factor (interspecific competition). Similar parapatric patterns have been previously described in other systems, suggesting they might be a common pattern in nature

Torres Dowdall et al. 11-0833 Standard Length data

Data use in the analysis of size at maturity. Data correspond to size at maturity of lab-reared male guppies (Poecilia reticulata). Size was measured as standard length of the fish (length column). Drainage refer to the drainage from were wild fish used to generate second generation of lab-reared experimental fish were collected. Pred refers to the community from which the wild caught fish were collected. LP represent low predation risk, simple fish communities. HP refer to downstream complex communities where predation risk is higher. Family refers to the family lines used in the experiment. Cue refers to the two treatments used in our experiment. hp means that fish were reared in the presence of predator cues, lp means that they were raised in the absence of such cues. Only significant interactions between terms were kept in the final model

Torres Dowdall et al. 11-0833 Procrustes coordinates data for Yarra fish

Data used in the analysis of head morphology from the Yarra Drainage. This text file contains the Procrustes Coordinates that were used for all multivariate analyses of morphology in the manuscript. The Procrustes Coordinates were produced by performing a Generalized Procrustes Analysis (GPA) on the original Cartesian Coordinates to remove size, orientation, and position effects from the data with the TPSRelw software packackage. Additionally, sliding semi-landmarks were aligned during the GPA with the TPSRelw software. Columns are as follow: “Id” refers to the individual assigned identification. Family refers to the family lines used in the experiment. “Predation” refers to the community from which the wild caught fish were collected; "low" represent low predation risk, simple fish communities; "High" refer to downstream complex communities where predation risk is higher. "Treatment" refers to the two treatments used in our experiment. "Cue" means that fish were reared in the presence of predator cues, "No Cue" means that they were raised in the absence of such cues. Drainage refer to the drainage from were wild fish used to generate second generation of lab-reared experimental fish were collected. Population refers to the interaction between Drainage and Predation. Data was analyzed in MANCOVA model combining both drainages, and later in separate CVAs

Torres Dowdall et al. 11-0833 Procrustes coordinates data for Guanapo fish

Data used in the analysis of head morphology from the Guanapo Drainage. This text file contains the Procrustes Coordinates that were used for all multivariate analyses of morphology in the manuscript. The Procrustes Coordinates were produced by performing a Generalized Procrustes Analysis (GPA) on the original Cartesian Coordinates to remove size, orientation, and position effects from the data with the TPSRelw software package. Additionally, sliding semi-landmarks were aligned during the GPA with the TPSRelw software. Columns are as follow: “Id” refers to the individual assigned identification. Family refers to the family lines used in the experiment. “Predation” refers to the community from which the wild caught fish were collected; "low" represent low predation risk, simple fish communities; "High" refer to downstream complex communities where predation risk is higher. "Treatment" refers to the two treatments used in our experiment. "Cue" means that fish were reared in the presence of predator cues, "No Cue" means that they were raised in the absence of such cues. Drainage refer to the drainage from were wild fish used to generate second generation of lab-reared experimental fish were collected. Population refers to the interaction between Drainage and Predation. Data was analyzed in MANCOVA model combining both drainages, and later in separate CVAs

Torres Dowdall et al. 11-0833 Water colum data

Data use in the analysis of water column use. Data correspond to proportion of guppies (Poecilia reticulata) using the surface of the water column. Drainage refer to the drainage from were wild fish used to generate second generation of lab-reared experimental fish were collected. Predation refers to the community from which the wild caught fish were collected. "low" represent low predation risk, simple fish communities. "High" refer to downstream complex communities where predation risk is higher. Family refers to the family lines used in the experiment. "trt" refers to the two treatments used in our experiment. "P" means that fish were reared in the presence of predator cues, "NP" means that they were raised in the absence of such cues. Only significant interactions between terms were kept in the final model

Torres-Dowdall etal. BJLS 2555.R1. Statistical niche model data

Data used in the construction and testing of the Statistical niche model of Poecilia reticulata and Poecilia picta. The column labeled ‘Data’ specifies if that location was used for training the model or testing it. The ‘Drainage/Area’ column indicates either the drainage or the geographic region where the river is located. The ‘Locality’ column gives more information on the location of sampling or the name of the river sampled. The ‘P.picta’ and ‘P.reticulata’ columns specify if that particular species was present or absent at that sampling locality. Then information about the sites is presented in the following order: latitude, longitude, elevation (measured in meters above sea level), salinity (measured in part per thousands), dissolved oxygen (measured in milligrams per liter), and pH. Finally, the date of sampling is indicated

Torres-Dowdall etal. BJLS 2555.R1. Phenotypic data

Data used in the analysis of phenotypic variation observed in wild-caught fish of Poecilia reticulata and Poecilia picta (‘Species’ column). Phenotypes measured in males include size and condition index (Kn). Phenotypes measured in females include reproductive allocation, fecundity, mean size of developing embryos, and condition index (Kn). ‘ID’ indicates internal collection number. ‘Sex’ specifies if data was collected from a male or a female. ‘Drainage’ refers to the drainage from where wild fish were collected. ‘Locality’ refers to the place along each drainage from where fish were collected (‘Upstream’ correspond to a freshwater-upstream locality where only P. reticulata occurred, ‘Midstream’ to a freshwater-midstream locality where both species were present, and ‘Downstream’ to a brackish water-downstream locality where only P. picta occurred). Size was measured as standard length of the fish (‘Length’ column, units in millimeters). Adult mass is presented as eviscerated dry mass (‘Mass’ column, units milligrams). ‘Kn’ refers to condition index, which was determined using this formula (Kn= Mi/aLib); where (a) is the intercept and (b) the slope of the least squares regression of log-transformed individual dry mass (Mi) on log-transformed individual standard length (Li). ‘#_Embryos’ was used to determine fecundity, and is a measure the number of developing embryos found in a female at the time of euthanasia. ‘Mean_offspring_mass’ is a measure of the size of each developing embryo at the time of the female’s euthanasia. ‘Reproductive_allocation’ is a measure of the percentage of the mass of a female dedicated to reproduction. ‘Mean_Stage’ is a measure of the developmental stage in which the embryos were at the time of the female’s euthanasia. Missing data or not corresponding data are showed as a dash