Dr. Else J. Fjerdingstad

Assistant Professor

Ph.D.(University of Århus, Denmark)

Office NSB E-118 Tel. (718) 997 3421; Laboratory NSB E-133 / 135 D Tel. (718) 997 xxxx / xxxx

E-mail: Else.Fjerdingstad@qc.cuny.edu;

Research interests:

The aim of evolutionary ecology and genetics is to understand the origin and maintenance of the complex biological world that surrounds us. Societies of living organisms, ranging from those of cells joining into eukaryotic or multicellular organisms, to the teeming colonies of social insects, constitute particularly intriguing examples of biological complexity. This is because social life introduces a new level of selection, the society or the kin group. The strategies of individuals influence society which in turn affects individuals, making individuals subject to social selection as well as direct selection. Understanding the evolution of life-history traits in social organisms is therefore especially challenging.

My research program focuses on the evolution of reproductive strategies, sociality and host-parasite co-evolution. I am interested in how sociality influences the evolution of reproductive strategies, how selection on reproductive strategies affects social evolution, and how host-parasite co-evolution affects both these aspects. To address these questions I use a variety of techniques, including field studies, molecular genetic analyses, ecological studies, behavioural experiments, laboratory assays and experiments, and comparative analyses.

An Atta leafcutter ant queen with small worker offspring in the fungus garden of a young colony. Ants of this genus show intriguingly complex mating systems, where each queen mates with 2 to 5 males on her mating flight (Fjerdingstad et al. 1998) despite this behavior likely imposing significant costs. This behavior may have evolved because multiple inseminations will boost the genetic diversity inside a queen’s future colony, which could increase colony survival in face of parasites and pathogens (but absence of evidence observed by Fjerdingstad et al. 1998), or facilitate the evolution of great worker caste diversity (Fjerdingstad and Crozier 2006). Also, multiple mating brings benefits to Atta queens because it allows them to obtain and store large numbers of sperm, thus increasing their lifetime potential reproductive success (Fjerdingstad and Boomsma 1998).

As test systems I mainly use the advanced social hymenopteran insects (ants, bees, and wasps) that build highly cooperative societies characterized by division of labour and reproduction between females, and show a challenging diversity of mating and breeding systems. I have worked on ants from all over the world, but many of my studies have concerned Panamanian fungus-growing ants and European black garden ants. Also, I have worked on single-celled protists possessing only a rudimentary semi-sociality.

With these animal systems I have addressed issues such as the evolution of multiple mating by social insect queens, social conflicts over resource allocation, the evolution of caste diversity, genetic variance in dispersal syndromes, and the importance of competition versus cooperation for dispersal strategies. The current and future research of my Laboratory focuses on the intersection of mating system evolution, social evolution and host-parasite co-evolution in insect societies.

Lasius niger, the very common black garden ant of Europe (above a worker, below a queen), is particularly interesting for studies on the evolution and maintenance of multiple mating by queens because populations in different countries differ in queen mating strategies (Boomsma and van der Have 1998). Queens of some populations almost always have only one mate and consequently the genetic diversity among worker offspring inside colonies is low, whereas queens in other populations almost invariably have two or more mates which leads to a greater genetic diversity inside their colonies (Fjerdingstad et al. 2002, 2003). Many theoretical models suggest that a high genetic diversity inside colonies could bring benefits to mother queens and colonies and so explain why queens mate multiply in some populations. Despite extensive testing and replications of tests, however, no hard evidence was found in favor of these hypotheses for this ant (Fjerdingstad et al. 2002, 2003, Fjerdingstad 2004, Fjerdingstad and Keller 2004). Instead it was found that differences in queen quality may help explain why some queens have only one mate and others many (male mate choice) (Fjerdingstad and Keller 2004), while queens also likely gain benefits by obtaining more sperm when having more mates (Fjerdingstad and Keller 2004).

Photographs by Jens Buurgaard Nielsen, This file is licensed under the Creative Commons Attribution ShareAlike 2.5 License.

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Selected Publications:

Fjerdingstad, E.J., N. Schtickzelle, P. Manhes, A. Gutierrez, and J. Clobert. 2007. Evolution of dispersal and
life history strategies – Tetrahymena ciliates. BMC Evolutionary Biology. 7:133 doi:10.1186/1471-2148-7-133

Fjerdingstad, E.J., and R.H. Crozier. 2006. The evolution of worker caste diversity in social insects. American Naturalist 167: 390-400.

Fjerdingstad, E.J. 2005. Control of body size of Lasius niger ant sexuals – worker interests, genes and environment. Molecular Ecology 14: 3123-3132.

Fjerdingstad, E.J., and L. Keller. 2004. Relationships between phenotype, mating behaviour, and fitness of queens in the ant Lasius niger. Evolution 58: 1056-1063.

Fjerdingstad, E.J. 2004. Multiple-paternity and colony homeostasis in Lasius niger ants. Behavioral Ecology and Sociobiology 56:50-58.

Fjerdingstad, E.J., P.J. Gertsch, and L. Keller. 2003. The relationship between multiple mating by queens, within-colony genetic variability and fitness in the ant Lasius niger. Journal of Evolutionary Biology 16:844-853.

Fjerdingstad, E.J., P.J. Gertsch, and L. Keller. 2002. Why do some social insect queens mate with several males? – testing the sex ratio manipulation hypothesis in Lasius niger. Evolution 56:553-562.

Full List of Publications:

Fjerdingstad, E.J., and R.H. Crozier. 2006. The evolution of worker caste diversity in social insects. American Naturalist 167: 390-400.

Fjerdingstad, E.J. 2005. Control of body size of Lasius niger ant sexuals – worker interests, genes and environment. Molecular Ecology 14: 3123-3132.

Fjerdingstad, E.J., and L. Keller. 2004. Relationships between phenotype, mating behaviour, and fitness of queens in the ant Lasius niger. Evolution 58: 1056-1063.

Fjerdingstad, E.J. 2004. Multiple-paternity and colony homeostasis in Lasius niger ants. Behavioral Ecology and Sociobiology 56:50-58.

Fjerdingstad, E.J., P.J. Gertsch, and L. Keller. 2003. The relationship between multiple mating by queens, within-colony genetic variability and fitness in the ant Lasius niger. Journal of Evolutionary Biology 16:844-853.

Fjerdingstad, E.J., P.J. Gertsch, and L. Keller. 2002. Why do some social insect queens mate with several males? – testing the sex ratio manipulation hypothesis in Lasius niger. Evolution 56:553-562.

Crozier, R.H., and E.J. Fjerdingstad. 2001. Polyandry in eusocial Hymenoptera – disunity in diversity? Annales Zoologici Fennici 38:267-285.

Fjerdingstad, E.J., and J.J. Boomsma. 2000. Queen mating frequency and relatedness in young colonies of Atta sexdens leafcutter ants. Insectes Sociaux 47:354-356.

Fjerdingstad, E.J., and L. Keller. 2000. The nature of ant colony success. (Technical comment) Science 287:1363b.

Boomsma, J.J., E.J. Fjerdingstad, and J. Frydenberg. 1999. Multiple paternity, relatedness and genetic diversity in Acromyrmex leafcutter ants. Proceedings of the Royal Society of London, Series B 266:249-254.

Fjerdingstad, E.J., and J.J. Boomsma. 1998. Multiple mating increases the sperm stores of leafcutter ant queens. Behavioral Ecology and Sociobiology 42:257-261.

Fjerdingstad, E.J., J.J. Boomsma , and P. Thorén. 1998. Multiple paternity in the leafcutter ant Atta colombica - a microsatellite DNA study. Heredity 80:118-126.

Gertsch, P., and E.J. Fjerdingstad. 1997. Biased amplification and the utility of spermatheca-PCR for mating frequency studies in Hymenoptera. Hereditas 126:183-186.

Fjerdingstad, E.J., and J.J. Boomsma. 1997. Variation in body size and potential reproductive success in sexuals of the leafcutter ant Atta colombica. Insectes Sociaux 44:209-218.

Boomsma, J.J., J. Søe Pedersen, and E.J. Fjerdingstad. 1994. Social evolution hos myrer. Naturens Verden 11:390-400.