Socially transferred materials: why and how to study them.

When biological material is transferred from one individual's body to another, as in ejaculate, eggs, and milk, secondary donor-produced molecules are often transferred along with the main cargo, and influence the physiology and fitness of the receiver. Both social and solitary animals exhibit such social transfers at certain life stages. The secondary, bioactive, and transfer-supporting components in socially transferred materials have evolved convergently to the point where they are used in applications across taxa and type of transfer. The composition of these materials is typically highly dynamic and context dependent, and their components drive the physiological and behavioral evolution of many taxa. Our establishment of the concept of socially transferred materials unifies this multidisciplinary topic and will benefit both theory and applications.

Strong Gene Flow Undermines Local Adaptations in a Host Parasite System.

The co-evolutionary pathways followed by hosts and parasites strongly depend on the adaptive potential of antagonists and its underlying genetic architecture. Geographically structured populations of interacting species often experience local differences in the strength of reciprocal selection pressures, which can result in a geographic mosaic of co-evolution. One example of such a system is the boreo-montane social wasp Polistes biglumis and its social parasite Polistes atrimandibularis, which have evolved local defense and counter-defense mechanisms to match their antagonist. In this work, we study spatial genetic structure of P. biglumis and P. atrimandibularis populations at local and regional scales in the Alps, by using nuclear markers (DNA microsatellites, AFLP) and mitochondrial sequences. Both the host and the parasite populations harbored similar amounts of genetic variation. Host populations were not genetically structured at the local scale, but geographic regions were significantly differentiated from each other in both the host and the parasite in all markers. The net dispersal inferred from genetic differentiation was similar in the host and the parasite, which may be due to the annual migration pattern of the parasites between alpine and lowland populations. Thus, the apparent dispersal barriers (i.e., high mountains) do not restrict gene flow as expected and there are no important gene flow differences between the species, which contradict the hypothesis that restricted gene flow is required for local adaptations to evolve.

Genetic analysis reveals Finnish Formica fennica populations do not form a separate genetic entity from F. exsecta.

Coptoformica Müller, 1923 is a subgenus of Formica Linnaeus, 1758 that consists of c. a dozen species of ants that typically inhabit open grassy habitats and build small nest mounds. The most recent addition to the group is Formica fennica Seifert, 2000. The description was based on morphological characters, but the species status has not been confirmed by molecular methods. In this study, we use thirteen DNA microsatellite markers and a partial mitochondrial COI gene sequence to assess the species status of F. fennica, by comparing the genetic variation among samples identified as F. fennica and six other boreal Formica (Coptoformica) species. Most of the species studied form separate, discontinuous clusters in phylogenetic and spatial analyses with only little intraspecific genetic variation. However, both nuclear and mitochondrial markers fail to separate the species pair F. exsecta Nylander, 1846 and F. fennica despite established morphological differences. The genetic variation within the F. exsecta/fennica group is extensive, but reflects spatial rather than morphological differences. Finnish F. fennica populations studied so far should not be considered a separate species, but merely a morph of F. exsecta.