Biology subjects

Telschow, A.

Publications and source records attributed to Telschow, A..

4 recordsLinked to original sources

bioRxiv2018

Evolutionary stability of plant-pollinator networks: efficient communities, hysteresis, and a pollination dilemma

Mutualistic interactions between species such as pollination and plant-mycorrhiza interactions are ubiquitous in nature and essential for ecosystem functioning. Often dozens or even hundreds of species with different degree of specialization form complex networks of interdependence. How the complexity evolved and is maintained are fundamental questions in ecology. Here, we present a new game theoretical approach to model complex mutualistic interactions, which we apply to pollination networks. The theoretical analysis revealed multiple evolutionary stable network structures that form a gradient from generalism toward specialism with increasing availability of pollination service. In particular, we found that efficient communities evolve only under pollination oversupply, but that pollination shortage selects for inefficient network structures due to a pollination dilemma. These results suggest that availability of pollination services is a key factor structuring pollination networks and offer a new explanation for the geographical differences in pollination faunas that have long been recognized by ecologists. The study bridges the gap between network studies, game theory, and the natural history of pollination, which have hitherto been studied largely independently.

ecology↗

bioRxiv2018

The infection dynamics of vertically transmitted viruses in a two-population model

1There is a growing interest in vertically transmitted viruses. Field studies show that virus infection frequency often varies in space and time. In order to understand the spatial variation of virus prevalence, we designed a mathematical model describing the infection dynamics of a biparentally inherited virus in a two-population model. Model parameters are paternal and maternal transmission rates, cost of infection, and up to two migration rates. We investigated three different population structures: (1) a single panmictic host population, (2) two populations connected by unidirectional migration (mainland-island model), and (3) two populations connected by two-way migration. According to the results, the parameter space can be divided in three zones: (1) viral spread, (2) no viral spread, (3) bistability (in a single population) or stable infection polymorphism (in the two-population models). The finding of bistability is interesting and new. It shows that infected and uninfected populations can stably coexist, if migration is below a critical value, and if the cost of infection is moderately high. In summary, our results show that spatial structure of host populations is an important factor in determining geographical differences of vertically transmitted viruses.

ecology↗

bioRxiv2018

Identify and predict environmental change effects on tiger mosquitos, Aedes polynesiensis

SO_SCPLOWUMMARYC_SCPLOWTo control mosquito populations for managing vector-borne diseases, a critical need is to identify and predict their response to causal environmental variables. However, most existing attempts rely on linear approaches based on correlation, which cannot apply in complex, nonlinear natural systems, because correlation is neither a necessary nor sufficient condition for causation. Appling empirical dynamic modelling that acknowledges nonlinear dynamics on nine subpopulations of tiger mosquitos from three neighbouring reef islets of the Raiatea atoll, we identified temperature, precipitation, dew point, air pressure, and mean tide level as causal environmental variables. Interestingly, responses of subpopulations in close proximity (100-500 m) differed with respect to their causal environmental variables and the time delay of effect, highlighting complexity in mosquito-environment causality network. Moreover, we demonstrated how to explore the effects of changing environmental variables on number and strength of mosquito outbreaks, providing a new framework for pest control and disease vector ecology.

ecology↗

bioRxiv2017

Signature Of Co-Evolution Between Defense And Vegetative Lifespan Strategies In Arabidopsis thaliana

The selective impact of pathogen epidemics on host defenses can be strong but remains transient. By contrast, life-history shifts can durably and continuously modify the balance between costs and benefits of immunity, which arbitrates the evolution of host defenses. Their impact on the evolutionary dynamics of host immunity, however, has seldom been documented. Optimal investment into immunity is expected to decrease with shortening lifespan, because a shorter life decreases the probability to encounter pathogens or enemies. Here, we document that in natural populations of Arabidopsis thaliana, the expression levels of immunity genes correlate positively with flowering time, which in annual species is a proxy for lifespan. Using a novel genetic strategy based on bulk-segregants, we partitioned flowering time-dependent from - independent immunity genes and could demonstrate that this positive co-variation can be genetically separated. It is therefore not explained by the pleiotropic action of some major regulatory genes controlling both immunity and lifespan. Moreover, we find that immunity genes containing variants reported to impact fitness in natural field conditions are among the genes whose expression co-varies most strongly with flowering time. Taken together, these analyses reveal that natural selection has likely assorted alleles promoting lower expression of immunity genes with alleles that decrease the duration of vegetative lifespan in A. thaliana and vice versa. This is the first study documenting a pattern of variation consistent with the impact that selection on flowering time is predicted to have on diversity in host immunity.

evolutionary biology↗