Graduate Research Program
Immunological and genetic mechanisims of host-pathogen interactions
(GK 1121)
in cooperation with "Zentrum für Infektionsbiologie
und Immunität (ZIBI)"
(begin:
01.04.2005)
"Evolutionary Transformations and Mass Extinctions", Museum
of Natural History, Berlin, Germany
(expires: 30.09.2005)
Radiation and extinction are important dynamic processes during the evolution
of species. Understanding the dynamics may lead to deeper insights into
the interrelations of evolutionary transformations. The extensive description
of these transformations and interpretation in the frame of an interdisciplinary
research program is the general aim of the graduate research program.
Scientists from disciplines like astrophysics, mineralogy, geology, palaeontology
and zoology jointly analyse and discuss the factors resulting in mass
extinction and radiation. The engagement of the IZW as an institute dealing
with evolutionary biology in the graduate research program "Evolutionary
Transformations and Mass Extinctions" enhances the cooperation with
different specialists on evolution. The speaker of the graduate research
program is Prof. Dr. U. Zeller, Institute of Systematic Zoology, Museum
of Natural History, Humboldt-University Berlin. [www.museum.hu-berlin.de]
Three theses within the subdivision B of the program "Mass extinctions
and evolutionary transformations: the impact on the evolution of Recent
taxa" are currently under investigation:
1. Evolution of locomotory
modes in the primitive Theria as a precondition for the radiation
of modern mammals after the Cretacious/Tertiary boundary (1998-2001).
Student: Ramón Vásquez Molinero, Supervisors: Prof. B. Krebs,
Dr. T. Martin (Institute of Palaeontology, FU Berlin) and Dr. R. Frey.
2. Strategies of adaptation
of Recent ruminant species to the seasonality of the vegetation (1998-
2001)
Student: Karin Lason, Supervisors: Dr. M. Lechner-Doll and Prof. R.R.
Hofmann.
Maternal energetic investment into reproduction in roe deer (Capreolus
capreolus) and Mouflon sheep (Ovis ammon musimon)
Maternal energy investment into lactation was estimated in roe
deer and mouflon sheep using stable isotope techniques in two different
approaches. The D2O dilution technique for estimating milk intake
described for sheep lambs by Coward et al. (1982) and the doubly
labelled water method for measuring energy expenditure (Speakman,
1997) were applied in parallel.
Energy expenditure in suckling roe deer fawns with a body mass
of 2 kg (0-2 weeks of age) was 1,4 MJ/d metabolisable energy (ME).
In addition to that up to 1,2 MJ/d were invested into growth. These
values lead to a maternal energy investment into lactation of at
least 5,4 MJ/d per fawn or 10,9 MJ/d in the case of twins.
Results from the D2O dilution technique where milk intake is
estimated are in accordance with these figures from the doubly labelled
water method. Milk intake was 1010 g/d in 10-14 day old mouflon
lambs and 570 g/d in a roe deer fawn of the same age. As milk composition
is quite different between the two species (roe deer milk contains
much more fat) maternal energetic investment into lactation may
be calculated to be 5,6 MJ/d in mouflon and 4,8 MJ/d in roe deer
per fawn.
3. Evolutionary differentiation and radiation of symbiotic protozoa
in the forestomach of selected ruminant species (2001-2004)
Supervisors: Dr. M. Lechner-Doll and Prof. H. Hofer.
This project is designed to investigate the evolutionary differentiation
and radiation of rumen protozoa in relation to the phylogenetic
position of their hosts. Because of the strict limitation to existence
in a rumen environment, protozoa are particularly well suited to
investigate this co-evolutionary relationships. Morphological identification
of the rumen protozoa suggests a relationship between the complexity
of protozoa populations and the feeding type of their hosts, which
in turn corresponds with the evolutionary stage of the differentiation
of the forestomach. Further evidence for an effect of vegetation
on the species composition of rumen protozoa were found. This supports
the hypothesis that if protozoan genera repeatedly invaded cervids,
today’s protozoan communities in cervids may in fact contain more
species than ancestral communities. This suggests that vertical
transmission (from mother to fawn) is the key mode but not the only
mode of protozoa transmission. First results of molecular genetic
analyses of samples of fallow deer look promising to reveal degrees
of evolutionary differentiation in the protozoan communities that
are inaccessible by standard morphological approaches.
|
