Project One: Costs & benefits of mating with immature females in the cannibalistic widow spider Latrodectus geometricus: assessing paternity
Males of the brown widow spider Latrodectus geometricus can avoid cannibalism by mating with immature females. However, when given a choice, they prefer to mate with mature, cannibalistic females. Such male preference can indicate that immature mating is costly. To investigate potential costs we will mate a female with two partners - one irradiated (sterile) and one non-irradiated (normal) male. One of these males will mate with a female while she is still immature. The sterile male technique will enable us to estimate relative paternity compared to matings with mature females, which will reveal potential fitness differences between the mating types (immature/mature).
Research field: behavioural ecology
Methods: behavioural observations, paternity assessment
Supervision: Lenka Sentenska, Yael Lubin, Gabriele Uhl
Start date: May/June 2018
Project Two: Vibrational communication in the wasp spider
Spiders are known to be very sensitive to substrate vibrations. Males and females often produce vibrational signals during mating, either to signal quality and assess the mate’s condition, or to signal species identity to prevent being attacked and eaten up. The function of vibratory signals during courtship of the wasp spider, Argiope bruennichi, will be investigated in detail. The project aims to investigate if vibratory signals honestly reflect male condition and if signals are used by females to accept or refuse a male. We also want to explore how the communication system works in nature – outside the lab, being subject to all kinds of disturbances such as wind, rain, or other vibrational noises.
Research field: behavioural ecology, biotremology, communication
Methods: behavioural observations (lab and field), Laser-Doppler-Vibrometry, morphometry
Supervision:Monika Eberhard, Gabriele Uhl
Start date: July/August 2018 or next year
Project Three: Cold tolerance of the range expanding wasp-spider Argiope bruennichi
The European wasp spider, Argiope bruennichi, has undergone a rapid latitudinal range expansion in Europe over the last 100 years, resulting in genetically distinct populations, which persist under different climatic conditions.Argiope bruennichi females lay eggs in autumn, shortly after which the eggs hatch within the egg sac. The hatched spiderlings then stay inside of the egg sac over winter, moult, and emerge in spring. Thus, they survive the most extreme winter conditions as spiderlings within the egg sac. These winter conditions are vastly different between the species’ central population in southern France, and the range-expanding front in Estonia. Thus, we are looking for an interested student to investigate the cold tolerance of spiderlings from the two regions raised under different simulated winter conditions.
Research field: animal adaptation, environmental change, cold tolerance
Methods: fine scale temperature measurement, LT50/LLT analysis, common garden experiment
Supervision: Monica M Sheffer, Gabriele Uhl
Start date: December/January 2019
Project Four: Overwintering physiology of Argiope bruennichi
Given the extreme conditions faced by Argiope bruennichi spiderlings overwintering in Estonia, we are interested in which physiological processes (i.e. upregulation of cryoprotectants such as antifreeze proteins and glycerol) occur over the course of winter, given different severities of temperature. Additionally, we would like to investigate if energy stores, such as lipids, are consumed at different rates under different winter temperature regimens. This will lend insight into the degree of physiological plasticity and the adaptive potential of these spiders to respond to changing and colder climates at the edge of their range.
Research field: biochemistry, environmental physiology
Methods: Gas chromatography-mass spectrometry (GC-MS), lipid analysis, common garden experiment
Supervision: Monica M Sheffer, Michael Lalk, Gabriele Uhl
Start date: Any time; Estonian spiderlings raised under 3 different winter treatments are available