Sebastian Pohl
Department Biologie II
Ludwig-Maximilians-Universität München
Großhaderner Str. 2
82152 Planegg-Martinsried
GERMANY
Tel: +49 (0)89 2180 74 216
Fax: +49 (0)89 2180 74 221
CV
Nationality German
Place and Date of Birth Idar-Oberstein, 26.05.1981
Education
2006 Diploma in Biology at the Albert-Ludwigs-Universität Freiburg
Topics: Evolution and ecology
Neurobiology / Physiology of animals
Biochemistry
French
Thesis title (translated): "The influence of different factors on the production of a replacement clutch in the burying beetle
Nicrophorus vespilloides HERBST (Coleoptera: Silphidae)"
2000 "Abitur" at the Gymnasium an der Heinzenwies, Idar-Oberstein
Grants
2010 Research and travel grant IRT 3 trial of the Munich Graduate Program for Evolution, Ecology and Systematics
2009 Research Grant of the E. N. Huyck Preserve and Biological Research Station, Rensselaerville, NY, USA
Title: "Host-parasite interactions in slavemaking ants and their slaves"
Research and travel grant IRT 3 trial of the Munich Graduate Program for Evolution, Ecology and Systematics
2008 Research Grant of the E. N. Huyck Preserve and Biological Research Station, Rensselaerville, NY, USA
Title: "Different fronts in the coevolutionary arms race of slavemaking ants and their hosts"
Research and travel grant IRT 3 trial of the Munich Graduate Program for Evolution, Ecology and Systematics
2007 Research Grant of the E. N. Huyck Preserve and Biological Research Station, Rensselaerville, NY, USA
Title: "Risk evaluation and decision making in slavemaking ants"
Publications
Pohl S, Foitzik S, 2011. Slave-making ants prefer larger, better defended host colonies. Animal Behaviour, 81:61-68.
Presentations
Pohl S, Foitzik S, 2011. Scouting behaviour and host worker response in slave making ants. 7th Ecology & Behaviour Meeting, Rennes
Pohl S, Foitzik S, 2010. Raid organisation and division
of labour in slave-making ants.
13th International
Behavioral Ecology Congress of the International Society for Behavioral
Ecology (ISBE), Perth
Pohl S, Foitzik S, 2010. Raid organisation and task
allocation in slave-making ants.
15th Graduate
Meeting of the Section Evolutionary Biology of the German Zoological
Society, Freiburg
Pohl S, Foitzik S, 2010. Raid organisation and division
of labour in slave-making ants.
6th Ecology
& Behaviour Meeting, Tours
Pohl S, Foitzik S, 2009. Decision making and host
nest choice in the slavemaking ant Protomognathus americanus.
1st Central European Meeting of the International
Union for the Study of Social Insects, Frauenchiemsee
Pohl S, Foitzik S, 2009. Risk evaluation and decision
making in slavemaking ants.
5th Ecology &
Behaviour Meeting, Lyon
Pohl S, Foitzik S, 2009. Risk evaluation and decision
making in slavemaking ants.
14th Graduate Meeting
of the Section Evolutionary Biology of the German Zoological Society,
Munich
Pohl S, Konrad M, Foitzik S, 2008. Behavioural and
chemical changes in orphaned Temnothorax ant workers.
13th Graduate Meeting of the Section Evolutionary
Biology of the German Zoological Society, Hamburg
Poster contributions
Pohl S, Foitzik S, 2010. Raid organisation and division
of labour in slave-making ants.
XVI Congress of the International
Union for the Study of Social Insects, Copenhagen
Pohl S, Foitzik S, 2009. Cost-benefit evaluation
and host nest choice in the slavemaking ant Protomognathus americanus.
102nd Conference of the German Zoological Society,
Regensburg
Pohl S, Steiger S, Müller JK, 2007. On the
benefit of filial infanticide in burying beetles.
12th
Graduate Meeting of the Section Evolutionary Biology of the German
Zoological Society, Bayreuth
Pohl S, Müller JK, 2006. The effect of potential
risk and potential benefit on the behaviour of widowed burying beetles.
11th International Behavioral Ecology Congress
of the International Society for Behavioral Ecology (ISBE), Tours
Media coverage
Science news websites:
BBC
online
Encyclopaedia
Britannica Blog
Bayerischer
Rundfunk online
Radio programs:
Adelaide Breakfast, 891
ABC Adelaide
Newspapers:
Süddeutsche Zeitung,
November 10th, 2010; available
online
Organization experience
Member of the Organization Board of the
1st
Central European Meeting
of the International Union for the Study of Social Insects and
the
3rd
Central European Workshop
in Myrmecology, Frauenchiemsee, October 8 - October 12, 2009
Work
Risk evaluation and decision making in slavemaking
ants
Parasitism is an interesting research field as it
provides a possibility to study interactions between different species
and may reveal some of the mechanisms of the course of evolution.
Social parasites provide the opportunity to investigate some basic
questions of parasitism under controlled conditions. The term "social
parasite" denominates social insects in which the members of
a colony exploit the worker force of other colonies (Hölldobler
and Wilson 1990). These host colonies may be formed by conspecifics
or heterospecifics, but a single parasitic species often uses only
one or very few species as hosts. This allows the evolution of adaptations
by the parasite to improve the hosts' exploitation as well as the
occurrence of counter-adaptations on the side of the hosts to lower
the impact of parasites on their own colony, which may result in
a coevolutionary arms race (Dawkins and Krebs 1979; Foitzik et al.
2001).
In slavemaking ants, a whole range of different life history varieties
exists, from species that only facultatively take advantage of other
colonies' workers to inquiline species in which the worker caste
is completely reduced and only a parasitic queen remains (Hölldobler
and Wilson 1990; Brandt et al. 2005). The North American myrmicine
species Protomognathus americanus is an obligate, dulotic social parasite (Wesson
1939). During the whole colony life cycle, it relies on slaves of
the genus Temnothorax:
T. longispinosus, T. curvispinosus and T. ambiguus.
The slavemaker colonies are small; beside the queen, a single colony
comprises a mean number of four to five slavemaker workers and 30
slaves (Herbers and Foitzik 2002). They can be found in hollow acorns,
twigs and hickory nuts on the ground of mixed deciduous forests
in the northeast of the United States and the adjacent Canadian
regions. A young, mated slavemaker queen enters a host colony and
kills or expels the resident queen and adult workers, whereas the
host pupae are allowed to hatch. Freshly emerged workers are imprinted
on the intruder and perform ordinary tasks like foraging or brood
care. Slavemaker workers, in contrast, are specializing in raiding
new host colonies to keep supplies of new slaves coming and thus
securing the survival of the colony. A quite similar host-parasite
system exists in European forests. The parasitic myrmicine Harpagoxenus sublaevis
depends on the worker force of its host species Leptothorax acervorum
and L. muscorum.
Unlike in the North American slavemaker species, the nests of H. sublaevis
contain on average more than 20 slavemaker workers and more than
75 slaves (Buschinger 1966; Buschinger 1974; Fischer and Foitzik
2004).
When a slavemaker colony is in need of new slaves, some slavemaker
workers, the so called "scouts", leave the nest and look
for a nearby host colony. Having found a nest of one of the host
species, a scout may enter the host nest before returning to her
own nest and recruiting other workers by tandem-running. When the
number of recruited workers is large enough, they start to attack
the host colony, kill or expel the host workers and transport the
pupae and larvae to their own nest (Wesson 1939). The host workers
on their part defend their brood and often immobilize and kill attacking
slavemaker workers. Therefore, the scouts should weigh the potential
benefit they may gain in the form of raided larvae and pupae against
the potential risk of losing nestmates due to the hosts' defense
before they start recruiting. The ability to estimate the consequences
of an attack will be particularly necessary if a single scout discovers
two different host nests before she returns to her own nest, allowing
her to recruit her nestmates to the host nest which provides the
highest benefit-per-cost ratio. Additionally, when two scouts find
two different host nests, they have to exchange their information
in order to come to a decision whether and which nest to raid. Studies
on decision making in social insects focused mainly on the nest
finding behavior in ants and honey bees. In slavemaking ants, the
slave raids additionally contain a risk component that is not present
in nest site choices, as large host nest are able to injure or kill
attacking slavemaking workers. Hence, the study of dulotic social
parasites offers new possibilities to investigate the process of
collective decision making in insects.
In my PhD thesis, I want to study the mechanisms of risk evaluation
and decision making in slavemaking ants. To conduct a successful
slave raid, the slavemakers have to make several decisions. Firstly,
they have to note a need of new slaves to start the search for new
host nests. Possible factors leading to the onset of this behavior
may be that the number of slaves reaches a lower threshold, or that
the slavemaker : slave ratio exceeds the tolerable limits. When
a scout then left its nest and found a host colony, it will be of
particular interest which demographic factors of the host nest influence
the scout's decision whether this nest is worth to be raided or
not and how this information is gained. Does she decide on the basis
of the potential benefit, e.g. the number of host brood item that
may be stolen, or the number of defending host workers which are
responsible for the potential costs of a slave raid by means of
killed slavemaker workers, or does she take both elements into account,
computing the ratio of both factors? Are chemical cues inside the
host nest sufficient transmitters of information to the scout or
does she need additional tactile contacts to get a picture of the
situation inside the host nest? It will be interesting to compare
the decisions of the North American social parasite Protomognathus americanus with those of its European counterpart Harpagoxenus sublaevis.
Protomognathus americanus colonies comprise fewer slavemaker workers than
the nests of H. sublaevis,
so I suggest that the former will show a rather risk-avoiding strategy
compared to the latter, as a loss of some slavemaker workers in
fights with the defending host workers has a greater impact on the
fitness of the smaller nests of the American social parasite. Finally,
before a slave raid can be started, the scouts have to recruit other
slavemaker workers to the host nest. I want to gain insight into
the process from individual information to collective decision making.
Which mechanisms, chemical or tactile ones, are used to transmit
the information about the chosen host nest? Are cuticular hydrocarbons
or gland secretions involved in this process? Additionally, I want
to know how an unambiguous decision will be reached if two scouts
discovered two different host nests.
A worker of Harpagoxenus sublaevis. |
A worker of Protomognathus americanus. |
Y-shaped raiding arena with three artificial
nest sites. |
