Kompetenzzentrum für Biodiversität und integrative Taxonomie (KomBioTa)

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/79

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Evolutionary genomics of socially polymorphic populations of Pogonomyrmex californicus
(2024) Errbii, Mohammed; Ernst, Ulrich R.; Lajmi, Aparna; Privman, Eyal; Gadau, Jürgen; Schrader, Lukas
Background: Social insects vary considerably in their social organization both between and within species. In the California harvester ant, Pogonomyrmex californicus (Buckley 1867), colonies are commonly founded and headed by a single queen (haplometrosis, primary monogyny). However, in some populations in California (USA), unrelated queens cooperate not only during founding (pleometrosis) but also throughout the life of the colony (primary polygyny). The genetic architecture and evolutionary dynamics of this complex social niche polymorphism (haplometrosis vs pleometrosis) have remained unknown. Results: We provide a first analysis of its genomic basis and evolutionary history using population genomics comparing individuals from a haplometrotic population to those from a pleometrotic population. We discovered a recently evolved (< 200 k years), 8-Mb non-recombining region segregating with the observed social niche polymorphism. This region shares several characteristics with supergenes underlying social polymorphisms in other socially polymorphic ant species. However, we also find remarkable differences from previously described social supergenes. Particularly, four additional genomic regions not in linkage with the supergene show signatures of a selective sweep in the pleometrotic population. Within these regions, we find for example genes crucial for epigenetic regulation via histone modification (chameau) and DNA methylation (Dnmt1). Conclusions: Altogether, our results suggest that social morph in this species is a polygenic trait involving a potential young supergene. Further studies targeting haplo- and pleometrotic individuals from a single population are however required to conclusively resolve whether these genetic differences underlie the alternative social phenotypes or have emerged through genetic drift.
Global biogeography of ant social parasites: Exploring patterns and mechanisms of an inverse latitudinal diversity gradient
(2022) Gray, Kyle W.; Rabeling, Christian
Aim: One of the most consistent global biogeographic patterns is the latitudinal diversity gradient where species richness peaks within the equatorial tropics and decreases towards the poles. Here, we explore the global biogeography of socially parasitic ant species, which comprises the most diverse group of social parasites in the Hymenoptera. We test the biogeographic hypothesis that ant social parasites are distributed along an inverse latitudinal diversity gradient (iLDG) by peaking in diversity outside of the equatorial tropics, which would contrast with the biogeographic pattern observed in free-living, non-parasitic ant species. Location: Global. Taxon: Ants (Hymenoptera: Formicidae). Methods: We assembled a comprehensive biogeographic dataset consisting of 6001 geographic distribution records for all 371 taxonomically described socially parasitic ant species. We used phylogenetic and taxonomic studies to estimate the number of independent evolutionary origins of ant social parasitism to directly compare species richness with the number of species representing independent evolutionary origins of social parasitism across a latitudinal gradient. In addition, we compared ant social parasite diversity across biogeographic regions using rarefaction to account for different sampling efforts. Finally, we tested for a correlation between latitude and the proportion of ant social parasite species within regional ant faunae. Results: The geographic distribution records and the inferred 91 independent evolutionary origins of socially parasitic life histories in ants show that both species richness and the number of species representing independent evolutionary origins of social parasitism peak in the northern hemisphere outside of the equatorial tropics. Based on rarefaction curves, northern latitude regions harbour the most ant social parasite species, but the diversity of independent evolutionary origins is not significantly different between northern and southern hemispheres. The proportion of ant social parasite species within regional faunae is tightly correlated with latitude only in the northern hemisphere. Main conclusions: The iLDG of ant social parasites contrasts with the biogeographic pattern observed in free-living, non-parasitic ant species and appears to be driven by large species radiations as well as by the presence of specialized life histories exclusive to the northern hemisphere.
Habitat requirements and home range use of the threatened garden dormouse (Eliomys quercinus) in a coniferous forest
(2025) Erhardt, Stefanie; Pfister, Jan; Beier, Marieke; Vorderbrügge, Rieke; Förschler, Marc I.; Fietz, Joanna
Understanding habitat use and requirements is essential for the conservation of endangered species, such as the garden dormouse (Eliomys quercinus). Therefore, we radio-tracked garden dormice (n = 39) in the Black Forest National Park (Germany) between 2019 and 2021, determined home range size by calculating autocorrelated kernel density estimates, located resting sites during the day, and analyzed their resting behavior. Furthermore, we investigated their crossing behavior across paths varying in width, in the degree of canopy closure, and understory. Median home range size was 3.8 ha (Q25 = 2.3 ha, Q75 = 6.6 ha) in adults and 1.9 ha in juveniles. Adult males increased their home range sizes during reproduction. In September, shortly before hibernation, adults used smaller home ranges, likely to save energy. During the day, garden dormice used nest boxes and natural nests under the ground as resting sites. Ground holes were an important resource as they were most frequently used by reproductive individuals and also at low ambient temperatures (0.1–14.7 °C). In contrast, nest boxes were used only at higher ambient temperatures (> 5.9 °C). Forest trails with tree cover and/or undergrowth were frequently crossed by adults, while 4 m wide forest paths without tree cover or undergrowth were rarely crossed. The results of our study show that the preservation of natural resting sites, the restoration of forest trails, or the installation of crossing structures are important conservation measures for the garden dormouse, facilitating migration and colonization of new habitats and reducing the risk to lose genetic variability.
Integrative description of Temnothorax siculus sp. n.: a new ant species from Sicily, Italy (Hymenoptera, Formicidae)
(2025) Schifani, Enrico; Alicata, Antonio; Prebus, Matthew M.; Csősz, Sándor; Fernández, Fernando; Guerrero, Roberto José
The mostly Holarctic genus Temnothorax (Hymenoptera, Formicidae) is the most diverse ant genus in temperate regions. The Mediterranean, a biodiversity hotspot of rare ant species, hosts over 150 Temnothorax taxa, including several short-range endemics. Over the last few years, phylogenomic reconstructions and integrative taxonomy have significantly improved the understanding of global Temnothorax diversity, but much taxonomic work is still needed in the Mediterranean region. Here, we present the integrative description of a new species of the genus, discovered in the central Mediterranean island of Sicily: Temnothorax siculus sp. n. is defined and compared to congeneric species integrating morphometrics and phylogenomics. It is a ground-nesting, lowland species, of which workers were regularly observed foraging on bushes and small trees. In the global phylogeny, covering all the main lineages of the region, it belongs to the Palearctic clade and is related to the tuberum and unifasciatus complexes. Morphological separation from other Sicilian Temnothorax species can generally be achieved on qualitative characters, but we also provide morphometric discriminant functions to separate it from T. apenninicus and especially T. unifasciatus . Temnothorax siculus has been rarely collected but appears to be widespread in Sicily, and may occur in neighboring regions.
Phylogenomic approach to integrative taxonomy resolves a century‐old taxonomic puzzle and the evolutionary history of the Acromyrmex octospinosus species complex
(2024) Mera‐Rodríguez, Daniela; Fernández‐Marín, Hermógenes; Rabeling, Christian
Accurately delimiting species boundaries is essential for understanding biodiversity. Here, we assessed the taxonomy of the leaf‐cutting ants in the Acromyrmex octospinosus (Reich) species complex using an integrative approach incorporating morphological, population genetic, phylogenetic and biogeographical data. We sampled populations across the biogeographic distribution of the species complex and reconstructed their evolutionary relationships using ultraconserved elements (UCEs) as molecular markers. We evaluated traditional morphological characters used to distinguish putative taxa and performed species delimitation analyses to investigate divergence between evolutionary lineages. Our results support the hypothesis that the A. octospinosus species complex consists of two species: the widely distributed and polymorphic species A. octospinosus and its inquiline social parasite A. insinuator Schultz et al. We consider A. echinatior (Forel) syn. nov . and A. volcanus Wheeler syn. nov . as well as the subspecies A. octospinosus cubanus Wheeler syn. nov ., A. octospinosus ekchuah Wheeler syn. nov . and A. octospinosus inti Wheeler syn. nov . as junior synonyms of A. octospinosus . We also investigated the biogeographic history of the species complex and the evolutionary origin of the social parasite A. insinuator . We inferred that A. octospinosus originated during the late Miocene approximately 6.9 Ma ago in the Neotropical rainforest. Acromyrmex insinuator shared a common ancestor with A. octospinosus approximately 3.4 Ma ago, with a crown‐group age of approximately 0.9 Ma. Our phylogeny supports the hypothesis that the inquiline social parasite speciated via the intra‐specific route of social parasite evolution in direct sympatry from its host. Our findings reshape our understanding of the A. octospinosus species complex and provide a foundation for future studies of Acromyrmex leaf‐cutting ants.

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