Subprojects

Theme 1: Morphological variation in Gastropods under extreme stress
Leonie Marschner
leonie.marschner at uni-tuebingen.de

Theme 2: Molecular analysis of factors determining fluctuating asymmetry in flowers
Anne Mohrholz
anne.mohrholz at uni-tuebingen.de

Theme 3: Fluctuating asymmetry in plants along steep and subtle environmental gradients – the role of biotic interactions
Bettina Springer
bettina.springer at bot.uni-tuebingen.de

Due to their inherently large potential for phenotypic plasticity, plants are understudied with respect to fluctuating assymmetry. Here, we want to fill this gap by investigating, for many species and in a very large range of environments, whether symmetry in plant leaves can be used as easy-to-measure proxy for fitness and for the level of stress a plant is exposed to. In contrast to previous studies we address two types of stress: biotic and abiotic stress. These are studied along three stress gradients: and aridity gradient in Israel, a nutrient gradient in South-Western Germany, and an altitudinal (temperature) gradient in the Northern Alps. Leaf symmetry is studied for a large number of species using field observations along the three natural stress gradients as well as greenhouse experiments with manipulations of drought stress. We test the hypotheses that a) symmetry decreases with increasing abiotic stress, b) facilitation may alleviate stress and thus increase symmetry, and c) competition may impose additional stress on plants which is expressed in the level of leaf symmetry.

Theme 4: Systematic deviation from bilateral symmetry in modern and fossil clypeasteroid sea urchins
Diedrich Sievers
diedrich_sievers at web.de

Theme 5: Symmetry in benthic and planktonic Foraminifera during rapid environmental change: fossil proxies and lab experiments
Manuel Weinkauf
mweinkauf at marum.de

Foraminifera range amongst the most abundant protists in the oceans. Planktonic forms originated in the Early Jurassic, and are important marine calcifiers. Benthic forms are abundant in coastal environments as well as in the deep sea since Cambrian times. Their wide temporal and spatial distribution makes them ideal environmental proxies.

In this project we focus on morphological deviations and fluctuating asymmetry s.lat. in Foraminifera, as a result of environmental stress. We hypothesise that
a rapid environmental changes can lead to rapid morphological changes in Foraminifera and
b the continuous exposure to high-stress environments can lead to a long-lasting, dynamic morphological change in certain species.

Two palaeontological datasets – one that covers the onset of Sapropel S5 in the Mediterranean Sea, and one from the Pleistocene of the Red Sea – will be complemented by manipulative laboratory experiments under controlled environmental conditions. This combination will allow us to study such reactions both on natural time scales under natural conditions (i.e. changes in several environmental factors at once), and under controlled laboratory conditions.

Certain morphological reactions of Foraminifera are already speculated to be the result of environmental stress. This works aims at a better understanding of factors governing those, and also more subtle, morphological changes, to gain a better understanding of ecophenotypic plasticity (which will ultimately lead to an enhancement of existing proxies using Foraminifera morphology) and its evolutionary value.