Abstracts (first author)

Invited Speaker 

Clinal selection in Drosophila: what have we learnt, where are we going?

Author(s): Hoffmann AA

Summary:

Clines have traditionally been used to investigate patterns of selection on phenotypes and genotypes involved in climatic adaptation. More recently, clines are being used to test for changes in patterns of adaptation across time. Modern genomic and transcriptomic approaches are now being applied to understand patterns of clinal adaptation at a fine level and to allow new sets of questions to be considered and a new level of understanding to be reached. Here I focus on recent Drosophila work to overview the opportunities and challenges provided by these new approaches and how they can be integrated into the more traditional work. I also consider the ways in which experimental work in field and laboratory settings can be used to further understand patterns of selection.


Invited Speaker 

Climate change adaptation: genetic and genomic approaches in Drosophila

Author(s): Hoffmann AA

Summary:

It is being increasingly appreciated that rapid evolutionary changes can help species counter the negative effects of global warming, and also that they can allow species to exploit favourable conditions provided in a warming world. There are now several well documented cases of rapid genetic change in response to natural and experimental warming in animals and plants. The genetic and genomic basis of these changes can be understood through comparisons of populations. Moreover, the genes and genomic regions identified in these comparisons can be further investigated through functional analyses on model organisms and along environmental gradients. Because related species often differ in their evolutionary potential, there is also an opportunity to investigate the genomic basis of limits to climate change adaptation, particularly as more sequenced genomes become available. I illustrate the opportunities provided through this framework by considering recent research on Drosophila. However I also highlight limitations of these approaches for predicting the dynamics of adaptive shifts in populations. Ideally genetic and genomic approaches need to be combined with quantitative studies of selection in populations.



Abstracts (coauthor)

Summary:

Humans impact ecosystems in a multitude of ways, increasingly exposing contemporary organisms to abiotic and biotic stressors. Environmental stress has strong negative impacts on biological diversity, as species can go locally extinct, if they are unable to migrate to a more benign habitat or to overcome the stressor via plastic or evolutionary adaptation. Several factors are thought to constrain adaptive evolution, such as gene flow, lack of genetic variation and genetic or functional trade-offs. Despite trade-offs being postulated as playing a central role in evolutionary theory, interactions between abiotic and biotic stress resistances have rarely been investigated in stress adaptation. This project aims to test for trade-offs between abiotic and biotic stress resistances in the well-established Drosophila melanogaster study system. Selection experiments on stress resistance provides an opportunity to study evolutionary constraints resulting from genetic trade-offs between traits. Lines that have been selected for different abiotic stressors (heat, cold and desiccation) will be tested for costs and benefits, whereas performance will be tested in outdoor cages under different biotic stressors (competition, predation, parasites) and under different climatic conditions (hot, moderate and cold days). These experiments provide a test of whether trade-offs between abiotic and biotic stress resistances are potential constraints to stress adaptation, which is crucial to better understand the evolutionary potential of contemporary populations.

Summary:

The maternally inherited intracellular bacteria Wolbachia are ubiquitous amongst arthropod hosts. Although well known for their ability to induce various host reproductive manipulations, Wolbachia have also been shown to increase host fitness by protecting against infectious microbes or increasing fecundity; and they are expected to evolve towards mutualism in natural host populations.

Recent data from our lab indicates the rapid sequential spread of two Wolbachia variants (wAu and wRi), only one of which induces significant reproductive parasitism in the form of cytoplasmic incompatibility, in Australian populations of Drosophila simulans over approximately 20 years. In each case analyses suggest that these dynamics are best understood as Fisherian waves of favourable variants, involving net host fitness benefits of a non-trivial magnitude.

Despite their leading roles in genetics, the suite of naturally occurring pathogens which significantly impact field populations of Drosophila melanogaster and D. simulans is not well characterized. Moreover specific infections (such as DMelSV) that are maintained for study in laboratory populations may have relatively benign effects in nature.

We have found that each of the wAu and wRi Wolbachia variants currently persist, at quite different infection frequencies, amongst geographically isolated populations of D. simulans within Australia. If these Wolbachia variants have the effect of promoting host fitness by protecting against infectious microbes, a comparison of these different host populations has potential to reveal pathogens that are ecologically significance and provide some indication of the intensity of the selective pressure they exert on a genetically tractable model host.

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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