Genetic tools in modern ecology

1
Genetic tools in modern ecology Three examples
to study conservation genetics S. Giere, B.
Schierwater H. Hadrys ITZ, Ecology
Evolution, TiHo Hannover, Bünteweg 17d, 30559
Hannover, Germany Ökologische Forschungsstätte
Bahnhof Schapen, Lindenallee 20, 38104
Braunschweig
Population structure and dynamics by means of
genetic markers For the conservation of
biodiversity it is essential to gain information
about the status of species and processes on
population level. In highly mobile organisms,
e.g. dragonflies, it is difficult to determine
population dynamics and population structures,
and thus to define reproductive and conservation
units. Here estimates of gene flow and genetic
diversity become a sine qua non (Giere Hadrys
2005, Hadrys et al. 2005, Groeneveld et al.
2006). Using molecular genetic data enables
us to monitor the genetic composition of defined
key species under various demographical and
ecological settings. The data provide insights
into the genetic structure, viability and
dispersal ability of natural populations which
differ in habitat selection, abundance, life
cycle parameters and dispersal behavior. By
combining multiple genetic markers, information
about different evolutionary time scales and
hence accounts for the historical dimension of
changes in biodiversity can be provided. As an
example, Figure 1 shows a haplotype network of 12
populations of Anax imperator based on the
mitochondrial ND1 region to investigate the
genetic variability and population dynamics
within this species (Timm et al. 2005).
Figure 1 Mutational haplotype network based on
statistical parsimony of 22 haplotypes and 12
populations of A. imperatos
Fine scale analyses with microsatellites in
conservation genetics Many ecosystems are highly
threatened by human impact resulting in
fragmentation, isolation and degradation of
habitats. This might have great consequences on
size and structure of populations. Decreasing
numbers of individuals in populations can lead to
a loss of genetic variability and hence the
ability to react to changing environmental
conditions. For a better understanding of the
consequences of such human interferences we
developed a microsatellite system (Hadrys et al.
2006a) for the keeled skimmer (O. coerulescens),
which is a red-listed species in Germany, to
investigate whether dredging of its breeding
habitat leads to immediate and long-term genetic
traces in the population structure. The high
sensitivity of microsatellite markers allows fine
scale examination of this problem (other
microsatellite systems see Giere Hadrys 2006
and Hadrys et al. 2006b). Analyses of individuals
from O. coerulescens before and directly after
agricultural dredging with 10 microsatellite loci
detected a loss of nearly all rare alleles. The
loss of alleles might influence the fitness of a
population and reduce its ability to respond to
environmental changes. Figure 2 shows an example
of the loss of alleles in one microsatellite
locus of Orthetrum coerulescens.
Figure 2 Allele size (bp) and frequencies () of
the microsatellite loci OrAB new allele ?
lost allele (CdV89, CdV98, CdV04)
Detection of variances in environmental
conditions by means of biomarkers The possibility
to adapt to different environmental conditions is
highly important for any kind of organisms
especially in times of global warming and
anthropogenic impacts of humans in their natural
habitats. The integration of physiology in
biodiversity research provides new insights into
the ability of adaptation of organisms in a
changing environment. With help of biomarkers
stressful situations can be detected much
earlier. The heat-shock protein Hsp70 belongs to
the big group of chaperons and is one of the
first genes expressed in an stressed organism.
Stress can be induced for example through
temperature shifts or anthropogenic impacts like
chemicals. The inclusion of Hsp70 as a biomarker
in conservation projects can provide an
early-warning measurement for environmental
changes and pollutions (Schroth et al. 2005).
Therefore we described the Hsp70 protein for
dragonflies to have a sensitive genetic tool for
analysing the water quality and the surrounding
vegetation of freshwater ecosystems.
Literature Giere S, Hadrys H (2005) Genetic
consequences of habitat specialisation and
cryptic speciation in the genus Trithemis. 4th
WDA International Symposium of Odonatology. Giere
S, Hadrys H (2006) Polymorphic microsatellite
loci to study population dynamics of a dragonfly,
the libellulid Trithemis arteriosa (Burmeister,
1839). Molecular Ecology Notes 6,
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(2006) Gigantism in Damselflies of Africa and
South America convergent evolution or homologous
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Phylogenetics and Evolution (in press). Hadrys H,
Clausnitzer V, Groeneveld LV (2005) The present
role and future promise of conservation genetics
for forest Odonates. In Forest and Dragonflies
(ed. Rivera A). Pensoft Publishers Sofia-Moscow,
Pontevedra, Spain. Hadrys H, Wargel A, Giere S,
Kraus B, Streit B (2006a) A panel of
microsatellite markers to detect and monitor
demographic bottlenecks in the riverine dragonfly
Orthetrum coerulescens F. Molecular Ecology Notes
in press. Hadrys H, Timm J, Streit B, Giere S
(2006b) A panel of microsatellite markers to
study sperm precedence patterns in the Emperor
Dragonfly Anax imperator (Odonata Anisoptera).
Molecular Ecology Notes in press. Schroth W,
Ender A, Schierwater B (2005) Molecular
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in moon jelly (Aurelia spp.). Mar Biotechnol (NY)
7, 449-461. Timm J, Hadrys H (2005) Comparative
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Samples were collected in Southern France (Crau/
Carmargue) and Germany/ Lower Saxony (Schapen and
Braunschweig region)