Abstracts (first author)

Talk 

Non-genetic inheritance generated by exposure to anthropogenic stressors in the water flea (Daphnia pulex)

Author(s): Collin H, Paterson S, Plaistow S

Summary:

Understanding how populations rapidly adapt to anthropogenic change is imperative for predicting limits to population persistence and reducing species extinction rates. Since most random mutations decrease fitness, and even those that increase fitness initially only occur in a single individual in the population, it is hard to envisage how new mutations alone can explain rapid evolutionary responses. Rapid adaptation might arise through ‘soft selection’ operating on standing genetic variation. However, an emerging, alternative hypothesis that is that environment-induced non-genetic inheritance facilitates and speeds up adaptive evolution.
By decoupling phenotypic change from genotypic change, non-genetic inheritance (parental effects and epiallelic variation) is not subject to the limitations typically associated with genetic inheritance. However, our lack of understanding of the mechanism that underpin non-genetic inheritance, the transience and instability of non-genetically transmitted phenotypic states, and the way that non-genetic inheritance interacts with genetic inheritance, all greatly limit our ability to evaluate the significance non-genetic inheritance for long-term evolutionary change. We addressed this shortfall by performing a 4-generation experiment in which we exposed 3 clones of Daphnia pulex to sub-lethal doses of novel freshwater pollutants (heavy-metal, endocrine disruptor, herbicide) and then quantified the patterns of non-genetic inheritance generated over the next three generations. This was done at the individual trait level as well as at the multivariate level, using phenotypic trajectory analysis to quantify stressor-induced patterns of phenotypic integration over multiple generations. We evaluate whether non-genetic inheritance accumulates, persists or dissipates over multiple generations, whether these patterns differ for different types of stressor, and whether there is an interaction between genetic and non-genetic inheritance.


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Abstracts (coauthor)

Summary:

Senescence is widely believed to be the evolved consequence of life-history strategies that are themselves shaped by extrinsic mortality. Consequently, evolutionary explanations of senescence are static. But recent studies investigating lifespan extension, genetic intervention and dietary restriction suggest that rates of senescence are plastic and may be regulated by the same mechanisms that underpin life-history plasticity. The Lansing effect refers specifically to plasticity in lifespan that are derived from maternal age effects: offspring from older mothers often senesce at faster rates. Lansing demonstrated this effect in rotifers over 60 years ago, and Lansing effects have now been observed in a broad range of taxa. However, there is still no evolutionary framework for the Lansing effect, or a mechanism explaining how maternal age effects are transmitted and alter offspring life-histories. We repeated Lansing's experiments in D. pulex. Using offspring from the first clutch to set up young maternal lines, and offspring from the fifth clutch to set up old maternal lines, we reared three clones for three generations. Offspring development, life-history and rates of senescence were then compared in the fourth generation. Lansing Effects were observed irrespective of the measure of senescence used, and varied in strength between clones. Offspring from old maternal lines were born larger, grew more, initiated maturation at larger sizes, and had increased early lifetime reproductive effort. However, differences in the growth and maturation decisions of offspring from young and old maternal lines were size-independent, supporting Lansing's assertion that older mothers transmit a non-genetic "ageing factor" to their offspring that alters their life-histories. We propose a novel adaptive explanation for the Lansing effect, and discuss the implications that an interaction between genetic and non-genetic inheritance have life-history evolution and population demography.

Contacts

Chairman: Octávio S. Paulo
Tel: 00 351 217500614 direct
Tel: 00 351 217500000 ext22359
Fax: 00 351 217500028
email: mail@eseb2013.com

Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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