Reconstructing the effects of fishing on life-history evolution in North Sea plaice Pleuronectes platessa
Mollet, F.M. ; Dieckmann, U. ; Rijnsdorp, A.D. - \ 2016
Marine Ecology Progress Series 542 (2016). - ISSN 0171-8630 - p. 195 - 208.
fisheries-induced evolution - eco-genetic model - reproductive investment - maturation reaction norms
Growing evidence suggests that fishing may induce rapid contemporary evolution in certain life-history traits. This study analyzes fisheries-induced changes in life-history traits describing growth, maturation, and reproduction, using an individual-based eco-genetic model that captures both the population dynamics and changes in genetic trait values. The model was successfully calibrated to match the observed life-history traits of female North Sea plaice Pleuronectes platessa around the years 1900 and 2000. On this basis, we report the following findings. First, the model indicates changes in 3 evolving life-history traits: the intercept of the maturation reaction norm decreases by 27%, the weight-specific reproductive-investment rate increases by 10%, and the weight-specific energy-acquisition rate increases by 1%. Together, these changes
reduce the weight at maturation by 46% and the asymptotic body weight by 28% relative to the intensification of fishing around 1900. Second, while the maturation reaction norm and reproductive- investment rate change monotonically over time, the energy-acquisition rate follows a more complex course: after an initial increase during the first 50 yr, it remains constant for about 30 yr and then starts to decline. Third, our analysis indicates that North Sea plaice has not yet attained a new evolutionary equilibrium: it must be expected to evolve further towards earlier maturation, increased reproductive investment, and lower adult body size. Fourth, when fishing continues in our model 100 yr into the future, the pace of evolution slows down for the maturation reaction norm and the rate of en ergy acquisition, whereas no such slowing down is expected for the rate of
Data from: On the fate of seasonally plastic traits in a rainforest butterfly under relaxed selection
Oostra, Vicencio ; Brakefield, P.M. ; Hiltemann, Y. ; Zwaan, Bas ; Brattström, O. - \ 2015
Constraints - Life History Evolution - Bicyclus sanaos - seasonality - Phenotypic Plasticity - Bicyclus anynana - Bicyclus martius - reproductive investment
Many organisms display phenotypic plasticity as adaptation to seasonal environmental fluctuations. Often, such seasonal responses entails plasticity of a whole suite of morphological and life-history traits that together contribute to the adaptive phenotypes in the alternative environments. While phenotypic plasticity in general is a well-studied phenomenon, little is known about the evolutionary fate of plastic responses if natural selection on plasticity is relaxed. Here, we study whether the presumed ancestral seasonal plasticity of the rainforest butterfly Bicyclus sanaos (Fabricius, 1793) is still retained despite the fact that this species inhabits an environmentally stable habitat. Being exposed to an atypical range of temperatures in the laboratory revealed hidden reaction norms for several traits, including wing pattern. In contrast, reproductive body allocation has lost the plastic response. In the savannah butterfly, B. anynana (Butler, 1879), these traits show strong developmental plasticity as an adaptation to the contrasting environments of its seasonal habitat and they are coordinated via a common developmental hormonal system. Our results for B. sanaos indicate that such integration of plastic traits – as a result of past selection on expressing a coordinated environmental response – can be broken when the optimal reaction norms for those traits diverge in a new environment.
Effect of Corticosterone and Hen Body Mass on Primary Sex Ratio in Laying Hen (Gallusgallus), Using Unincubated Eggs1
Aslam, M.A. ; Groothuis, T.G.G. ; Smits, M.A. ; Woelders, H. - \ 2014
Biology of Reproduction 90 (2014)4. - ISSN 0006-3363
maternal condition - reproductive investment - potential mechanisms - testosterone affects - passerine bird - zebra finches - tree swallows - in-vitro - 1st eggs - manipulation
In various studies, chronic elevation of corticosterone levels in female birds under natural or experimental conditions resulted in female biased offspring sex ratios. In chicken, one study with injected corticosterone resulted in a male sex ratio bias. In the current study, we chronically elevated blood plasma corticosterone levels through corticosterone feeding (20 mg/kg feed) for 14 days using 30 chicken hens in each of treatment and control groups and studied the primary offspring sex ratio (here defined as the proportion of male fertile eggs determined in freshly laid eggs, i.e., without egg incubation). Mean plasma corticosterone concentrations were significantly higher in the treatment group but were not associated with sex ratio, laying rate, and fertility rate. Corticosterone treatment by itself did not affect egg sex but affected sex ratio as well as laying rate and fertility rate in interaction with hen body mass. Body mass had a negative association with sex ratio, laying rate, and fertility rate per hen in the corticosterone group, but a positive association with sex ratio in untreated hens. These interactions were already seen when taking the body mass at the beginning of the experiment, indicating intrinsic differences between light and heavy hens with regard to their reaction to corticosterone treatment. The effects on laying rate, fertility rate, and sex ratio suggest that some factor related to body mass act together with corticosterone to modulate ovarian functions. We propose that corticosterone treatment in conjunction with hen body mass can interfere with meiosis, which can lead to meiotic drive and to chromosomal aberrations resulting in postponed ovulation or infertile ova.
Can fisheries-induced evolution shift reference points for fisheries management?
Heino, M. ; Baulier, L. ; Boukal, D.S. ; Mollet, F.M. ; Rijnsdorp, A.D. - \ 2013
ICES Journal of Marine Science 70 (2013)4. - ISSN 1054-3139 - p. 707 - 721.
cod gadus-morhua - north-sea plaice - life-history evolution - exploited fish stocks - pleuronectes-platessa l - eco-genetic model - atlantic cod - population-dynamics - reproductive investment - natural mortality
Biological reference points are important tools for fisheries management. Reference points are not static, but may change when a population's environment or the population itself changes. Fisheries-induced evolution is one mechanism that can alter population characteristics, leading to “shifting” reference points by modifying the underlying biological processes or by changing the perception of a fishery system. The former causes changes in “true” reference points, whereas the latter is caused by changes in the yardsticks used to quantify a system's status. Unaccounted shifts of either kind imply that reference points gradually lose their intended meaning. This can lead to increased precaution, which is safe, but potentially costly. Shifts can also occur in more perilous directions, such that actual risks are greater than anticipated. Our qualitative analysis suggests that all commonly used reference points are susceptible to shifting through fisheries-induced evolution, including the limit and “precautionary” reference points for spawning-stock biomass, Blim and Bpa, and the target reference point for fishing mortality, F0.1. Our findings call for increased awareness of fisheries-induced changes and highlight the value of always basing reference points on adequately updated information, to capture all changes in the biological processes that drive fish population dynamics.