I joined iDiv because…
It is a great opportunity for me to collaborate with excellent researchers from a variety of research fields and to connect my research project to other current hot topics in biodiversity research.
Background/ previous research
I’ve studied biology at the University of Leipzig focusing on the biodiversity and evolution of animals. Since I’m particularly interested in species conservation my Bachelor thesis dealt with a new concept for setting conservation priorities. My Masters project focused on the population genetics of a South African bee species and allowed me to develop my scientific skills in the field of genetics and molecular ecology. With my PhD project I want to deepen and broaden my knowledge in these research areas and aim to yield results that help to inform conservation management of bee- and phyto-diversity in South Africa.
Research focus/interest/current research
Conservation biology, Pollinator-plant coevolution, Evolutionary genetics
„Evolutionary genetics of a bizarre adaptation: giant front legs of Rediviva bees as an adaptation to their Diascia hosts in the winter rainfall area of South Africa”
Understanding the co-evolutionary processes between plants and their pollinators is of increasing relevance given the worldwide decline of bee species and the associated threats for phytodiversity and food security. The Rediviva-Diascia-system in the winter rainfall area of South African represents a fascinating example of a co-evolutionary relationship. Rediviva bees have evolved elongated fore legs in order to collect floral oil from a variety of plant taxa. Plants of the genus Diascia represent the main host of Rediviva and produce oil inside their spurs. The spur length of Diascia and the leg length of its pollinator Rediviva varies not only among species of the respective genera but also from population to population within a species. Morphological studies have revealed a significant correlation between the length of the bees’ forelegs and the oil-producing spurs of its local host Diascia, strongly supporting the idea of co-evolution. The aim of my PhD-project is to investigate the genetics and evolutionary consequences of the co-evolutionary relationship between Rediviva and Diascia, which contributes to the great biodiversity of the South African Succulent Karoo.
The knowledge gap
Although morphological analyses strongly support a co-evolutionary relationship between Rediviva and Diascia, genetic data underlying this co-evolutionary process are lacking, yet would give insights into the targets of selection and the evolution of adaptions. It is neither known which loci regulate leg length variation and are thus responsible for the adaptation of Rediviva to its host, nor is there information about the evolutionary origin and consequences of this adaptation.
Research question / Hypotheses
- In the phylogenetic part of my project I will study the evolution of leg length variance within the genus Rediviva and provide an answer to questions such as if long legs have a single origin or if they have evolved independently multiple times. I also aim to detect signatures of coevolution by comparing phylogenies for Rediviva and Diascia and testing for topological and temporal congruence.
- With the genomic analyses I want to identify the genes underlying leg length variance in Rediviva. I will first identify candidate genes in one Rediviva species and then test if the same loci control leg length in other Rediviva species, too.
- The population genetic analyses of one Rediviva species will provide an answer to what extend gene flow is going on between populations and how gene flow impacts the adaptation of bees to its host.
Links to the main questions of iDiv / Links to other iDiv projects?
My project targets three of the four main questions of iDiv. Since I am trying to identify loci controlling leg length variation, I will investigate a key trait, which triggers ecological speciation in Rediviva and is also very likely to influence speciation of its host thereby contributing to the bee- and phyto-diversity of the Succulent Karoo. By using a phylogenetic approach I aim to detect the origin of long legs and study the evolution of leg length variance. These analyses will give information about the emergence and maintenance of diversity in the genus Rediviva. Moreover, the population genetic analyses of Rediviva species will enable inferring the threat status of populations and provide basic information for conservation management of Rediviva in the Succulent Karoo.
Methods to be used
Phylogenetic analyses will be used to investigate the evolution of leg length variance in Rediviva. By comparing my reconstructed Rediviva phylogeny to a phylogeny of its host Diacia (co-phylogenetic analyses) I will also test for signatures of co-evolution on a molecular basis.
To identify putative loci controlling leg length variation, I will generate a high coverage genome for a Rediviva individual and sequence around 30 individuals from two populations significantly differing in leg length. Two different approaches, namely FST- outlier analyses and the ratio of non-synonymous to synonymous substitutions (dN/dS), will be employed to identify then genomic regions under selection that potentially underlie variance in leg length.
The population structure of Rediviva species will be examined using standard methods in population genetics such as FST- analyses and Bayesian clustering.
2013 - present
PhD student, Martin Luther Universität Halle-Wittenberg, Institute of Biology, General Zoology
2007 - 2010
B.Sc. Biology, University of Leipzig
Bachelor’s thesis: ‘Importance of the range size and biogeographical distribution for evaluating the national responsibility for reptiles in Europe’
Theodorou, P., Radzevičiūtė, R., Lentendu, G., Kahnt, B., Husemann, M., Bleidorn, C., Settele, J., Schweiger, O., Grosse, I., Wubet, T., Murray, T. E., Paxton, R. J.(2020): Urban areas as hotspots for bees and pollination but not a panacea for all insects. Nature Communications 11(1) *
Kahnt, B., Theodorou, P., Soro, A., Hollens-Kuhr, H., Kuhlmann, M., Pauw, A., Paxton, R. J.(2018): Small and genetically highly structured populations in a long-legged bee, Rediviva longimanus, as inferred by pooled RAD-seq. BMC Evolutionary Biology 18, 196
Theodorou, P., Radzevičiūtė, R., Kahnt, B., Soro, A., Grosse, I., Paxton, R. J.(2018): Genome-wide single nucleotide polymorphism scan suggests adaptation to urbanization in an important pollinator, the red-tailed bumblebee (Bombus lapidarius L.). Proceedings of the Royal Society B: Biological Sciences 285(1877)
Kahnt, B., Montgomery, G. A., Murray, E., Kuhlmann, M., Pauw, A., Michez, D., Paxton, R. J., Danforth, B. N.(2017): Playing with extremes: Origins and evolution of exaggerated female forelegs in South African Rediviva bees. Molecular Phylogenetics and Evolution 115, 95-105
Kahnt, B., Gerth, M., Paxton, R. J., Bleidorn, C., Husemann, M.(2015): The complete mitochondrial genome of the endemic and highly specialized South African bee species Rediviva intermixta (Hymenoptera: Melittidae), with a comparison with other bee mitogenomes. Biological Journal of the Linnean Society 116(4), 940-53
Kahnt, B., Soro, A., Kuhlmann, M., Gerth, M., Paxton, R. J.(2014): Insights into the biodiversity of the Succulent Karoo hotspot of South Africa: the population genetics of a rare and endemic halictid bee, Patellapis doleritica. Conservation Genetics 15(6), 1491-1502
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