https://repositorio.uchile.cl/handle/2250/170605 Centro Nacional del Medio Ambiente (CENMA) Tue, 05 May 2026 19:44:33 GMT 2026-05-05T19:44:33Z https://repositorio.uchile.cl/handle/2250/149646 Evolution of a predator induced, nonlinear reaction norm Carter, Mauricio J.; Lind, Martin I.; Dennis, Stuart R.; Hentley, William; Beckerman, Andrew P. Inducible, anti-predator traits are a classic example of phenotypic plasticity. Their evolutionary dynamics depend on their genetic basis, the historical pattern of predation risk that populations have experienced and current selection gradients. When populations experience predators with contrasting hunting strategies and size preferences, theory suggests contrasting micro-evolutionary responses to selection. Daphnia pulex is an ideal species to explore the microevolutionary response of anti-predator traits because they face heterogeneous predation regimes, sometimes experiencing only invertebrate midge predators and other times experiencing vertebrate fish and invertebrate midge predators. We explored plausible patterns of adaptive evolution of a predator-induced morphological reaction norm. We combined estimates of selection gradients that characterize the various habitats that D. pulex experiences with detail on the quantitative genetic architecture of inducible morphological defences. Our data reveal a fine scale description of daphnid defensive reaction norms, and a strong covariance between the sensitivity to cues and the maximum response to cues. By analysing the response of the reaction norm to plausible, predator-specific selection gradients, we show how in the context of this covariance, micro-evolution may be more uniform than predicted from size-selective predation theory. Our results show how covariance between the sensitivity to cues and the maximum response to cues for morphological defence can shape the evolutionary trajectory of predator-induced defences in D. pulex. Sun, 01 Jan 2017 00:00:00 GMT https://repositorio.uchile.cl/handle/2250/149646 2017-01-01T00:00:00Z https://repositorio.uchile.cl/handle/2250/145630 Ontogenetic shift in Daphnia-algae interaction strength altered by stressors: revisiting Jensen’s inequality Ramos Jiliberto, Rodrigo; Heine Fuster, Inger; Reyes, Claudio A.; González Barrientos, Javier Interaction strength among species plays a crucial role in shaping the functioning of ecological communities, but it is often assumed to be insensitive to inter-individual variation in underlying parameters such as attack rates or handling time. Ecological factors including stressors exert age/size-dependent effects on such behavioral parameters, promoting shifts in the distribution of parameter values over ages. Here we analyze the effects of the pesticide methamidophos on the Daphnia-microalga interaction strength. We first analyze age-dependent effects of the pesticide on the Daphnia functional response, and then decompose the population-level effects of the stressor into contributions of shifts in elevation (i.e., vertical effect) versus shifts in nonlinearity (i.e., nonlinear effect) of the response of interaction strength over consumer age. Our results show that (1) Rogers and Holling type II functional response models best fitted the empirical functional responses of Daphnia of different ages, (2) attack rate and handling time were affected by the pesticide, (3) these effects were age-specific, shifting the average attack rate and both the mean and coefficient of variation of handling time of different age classes, (4) population level interaction strength was affected by pesticide exposure by variation in both elevation and nonlinearity of its response over consumer age. We show that both vertical and nonlinear effects were important in magnitude but opposite in sign. The consequences of factors that exert age/size dependent effects can only be evaluated through properly considering inter-individual variation. Fri, 01 Jan 2016 00:00:00 GMT https://repositorio.uchile.cl/handle/2250/145630 2016-01-01T00:00:00Z https://repositorio.uchile.cl/handle/2250/139443 Do female Nicrophorus vespilloides reduce direct costs by choosing males that mate less frequently? Hopwood, P. E.; Mazué, G. P. F.; Carter, M. J.; Head, M. L.; Moore, A. J.; Royle, N. J. Sexual conflict occurs when selection to maximize fitness in one sex does so at the expense of the other sex. In the burying beetle Nicrophorus vespilloides, repeated mating provides assurance of paternity at a direct cost to female reproductive productivity. To reduce this cost, females could choose males with low repeated mating rates or smaller, servile males. We tested this by offering females a dichotomous choice between males from lines selected for high or low mating rate. Each female was then allocated her preferred or non-preferred male to breed. Females showed no preference for males based on whether they came from lines selected for high or low mating rates. Pairs containing males from high mating rate lines copulated more often than those with low line males but there was a negative relationship between female size and number of times she mated with a non-preferred male. When females bred with their preferred male the number of offspring reared increased with female size but there was no such increase when breeding with non-preferred males. Females thus benefited from being choosy, but this was not directly attributable to avoidance of costly male repeated mating. Artículo de publicación ISI Fri, 01 Jan 2016 00:00:00 GMT https://repositorio.uchile.cl/handle/2250/139443 2016-01-01T00:00:00Z https://repositorio.uchile.cl/handle/2250/138207 The alignment between phenotypic plasticity, the major axis of genetic variation and the response to selection Lind, Martin I.; Yarlett, Kylie; Reger, Julia; Carter, Mauricio J.; Beckerman, Andrew P. Phenotypic plasticity is the ability of a genotype to produce more than one phenotype in order to match the environment. Recent theory proposes that the major axis of genetic variation in a phenotypically plastic population can align with the direction of selection. Therefore, theory predicts that plasticity directly aids adaptation by increasing genetic variation in the direction favoured by selection and reflected in plasticity. We evaluated this theory in the freshwater crustacean Daphnia pulex, facing predation risk from two contrasting size-selective predators. We estimated plasticity in several life-history traits, the G matrix of these traits, the selection gradients on reproduction and survival, and the predicted responses to selection. Using these data, we tested whether the genetic lines of least resistance and the predicted response to selection aligned with plasticity. We found predator environment-specific G matrices, but shared genetic architecture across environments resulted in more constraint in the G matrix than in the plasticity of the traits, sometimes preventing alignment of the two. However, as the importance of survival selection increased, the difference between environments in their predicted response to selection increased and resulted in closer alignment between the plasticity and the predicted selection response. Therefore, plasticity may indeed aid adaptation to new environments. Artículo de publicación ISI Thu, 01 Jan 2015 00:00:00 GMT https://repositorio.uchile.cl/handle/2250/138207 2015-01-01T00:00:00Z