A.F.T. (Aurelia) Strauss, MSc

PhD project

Most organisms organise their diel activities through circadian clocks, which in turn are entrained to environmental cues such as daylight. Similar mechanisms apply to the annual cycles that also involve the circadian system. Here, I will investigate the selection pressure on circadian systems in wild birds as well as the consistency of individual time-keeping between years and within pedigrees. Further, the performance of different chronotypes in response to environmental conditions will be examined.

For this purpose, I will record body temperature cycles and chronotypes of a wild Great Tit (Parus major) population on the island of Vlieland (NL) which has been subject to systematic long-term breeding studies. Thus, detailed data on pedigree and fitness in relation to phenotype can be used to quantify patterns of inheritance. Extreme early and late chronotypes will be experimentally tested for corresponding differences in circadian rhythms in captivity.

Furthermore, genotyped Great Tits from a large-scale breeding experiment will be tested for circadian rhythmicity to link genotype and phenotype. Repeated testing in two seasons (early spring and autumn) will shed light on repeatability and annual modulation of circadian measures. Preliminary results of the first spring testing will be presented.

Former Projects

Sugar preference in several migratory passerines (master thesis)
Previous research suggests that birds have lost the mammalian-like sweet receptor. However, many songbirds have sugary diet such as fruit and/or nectar. To test sugar taste preferences, different migratory songbirds were exposed to behavioural two choice preference assays. European starlings were tested captive whereas a wide range of songbirds was tested in the field during spring migration at Ponza (Italy).
Lab Dr. Maude Baldwin, Max-Planck Institute (MPI) for Ornithology in Seewiesen, Germany

Does air humidity affect the timing of leaf-out in temperate woody plants? (research project & publication) DOI
A new concept shows that the leaf-out of trees might be mainly stimulated by the accumulation of humidity instead of air temperature. Contrary findings were archived by different studies using twig cuttings. In this project, seedlings of 10 tree species were exposed to elevated humidity or to control/arid humidity in two greenhouse chambers. Phenological observations show that temperature, rather than air humidity, triggers the leaf-out in these seedlings.
Lab Prof. Susanne Renner, Ludwig-Maximilians Universität (LMU) in Munich and Botanischer Garten München, Germany

Mixing depth influences species composition of marine zooplankton (research project)
Increased water temperature interrupts mixing of the water layers and thereby influences the phytoplankton community. This might lead to changes in zooplankton communities as well. Microscopic counting of marine zooplankton, sampled during a mesocosm experiment, was analysed for differences in species abundance and composition. Zooplankton composition was affected by mixing depth.
Lab Dr. Maria Stockenreiter, LMU in Munich, Germany

Does overnight temperature influence the singing behaviour in wild great tits, Parus major? (bachelor thesis & publication) DOI
Vocalisations are crucial for appropiate territory defence in wild great tits. When resources are limited, energy reserves have to be spent cautious. Thus, energetical trade-offs might also affect the response to intruders. Acoustic responses to simulated territorial intrusions were obtained in wild great tits. Using weather station data, we could show that lower ambient temperatures (rather than night temperature) lead to a shift from singing to alarming during territorial defence.
Lab Prof. Niels Dingemanse, LMU in Munich and MPI Ornithology in Seewiesen, Germany

Preference for oviposition site depending on egg density and the effects of associated larval competition in Callosobruchus maculatus (research project)
Intraspecific competition occurs when individuals depend on the same resources. In bean beetles, the larvae develop fully in the females' chosen bean and therefore, the larval competition of larvae is fully dependent on the female's decision for oviposition. Preference tests were conducted providing beans without and with a previous egg. Females preferred beans without eggs for oviposition. Also, life history traits of offspring were measured. Larval competition affected hatch rate, survival, developmental time and female’s body size.
Lab Dr. Fiona Hunter, University of Sheffield, United Kingdom