2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

����41 Faten Gabsi
A modeling approach to characterize population-level effects of sub-lethal
exposure to toxicants in Daphnia magna
Authors: Faten Gabsi 1 , Thomas Preuss 1
Affiliation: 1 RWTH-Aachen University
In this study, we aim to determine how sub-lethal effects measured on individuals
affect population properties in Daphnia magna.
Toxicant-induced changes on individuals translate differently at the population level.
For instance, population decline may arise from simple affected individual-level
endpoints, whereas a significant influence on other endpoints might have negligible
impact on population size and/or structure.
Population modeling has been used as a powerful tool to extrapolate measured
effects on individuals to the population level. It allows including the variability
between individuals in response to chemical’s exposure and accounting for the
different mechanisms of action of a toxicant.
In this work, we use an already developed and validated individual-based model for
D. magna (IDamP, see Preuss et al, 2009) as a virtual laboratory in order to
investigate the sub-lethal effects of a hypothetical toxicant on the population level,
and to compare their relative magnitudes of effects.
Different simulation scenarios will be tested: Effects on reproductive performance
might be exerted via various mechanisms like reduction in the filtration rate, delay in
the time to first reproduction, etc. A slowed or inhibited growth induced by exposure
to the toxicants will also be assessed solely or combined to reproductive effects.
Modeling these different responses will be addressed in combination to varying
environmental factors like variable food levels.
Using such an approach allows us to explain the interactions between natural factors
and toxicity at the level of individuals which ultimately emerge as effects on
populations’ properties.
����42 Michael Gerth
Patterns of Wolbachia infections in bees (Anthophila)
Authors: Michael Gerth 1 , Juliane Röthe 1 , Denise Aumer 1 , Christoph Bleidorn 1
Affiliation: 1 University Leipzig, Institute for Biology, Molecular Evolution & Animal
Systematics
Endosymbiotic bacteria of the genus Wolbachia infect nematodes, arachnids,
crustaceans and insects with a prevalence of up to 66%. The various ways Wolbachia
alters the reproduction of its hosts and thereby promotes its own vertical
transmission have received much attention. Recently, it has become clear that the
high prevalence and worldwide spread of Wolbachia has happened through frequent
lateral transfers of infections between even distantly related hosts. The mechanisms
thereof are only partially understood.
In bees (Anthophila), Wolbachia infects about two thirds of all species. A previous
study has suggested that many strains are transmitted horizontally among bees. The
biology of bees is well studied and therefore they represent a good model for the
investigation of horizontal transfer of Wolbachia.
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