Biology subjects

Schmitt, T.

Publications and source records attributed to Schmitt, T..

3 recordsLinked to original sources

bioRxiv2018

Species composition and altitudinal distribution of bumble bees (Hymenoptera: Apidae: Bombus) in the East Himalaya, Arunachal Pradesh, India

The East Himalaya is one of the worlds most biodiverse ecosystems. Yet, very little is known about the abundance and distribution of many plant and animal taxa in this region. Bumble bees are a group of cold-adapted and high altitude insects that fulfill an important ecological and economical function as pollinators of wild and agricultural flowering plants and crops. The Himalayan mountain range provides ample suitable habitats for bumble bees. Himalayan bumble bees have been studied systematically for a few decades now, with the main focus on the western region, while the eastern part of the mountain range received little attention and only a few species are genuinely reported. During a three-year survey, we collected more than 700 bumble bee specimens of 21 species in Arunachal Pradesh, the largest of the north-eastern states of India. We collected a range of species that were previously known from a very limited number of collected specimens, which highlights the unique character of the East Himalayan ecosystem. Our results are an important first step towards a future assessment of species distribution, threat and conservation. We observed clear altitudinal patterns of species diversity, which open important questions about the functional adaptations that allow bumble bees to thrive in this particularly moist region in the East Himalaya.

zoology↗

bioRxiv2018

Reinforcement targets sexual or postmating prezygotic reproductive barriers depending on species abundance and population history

The impact of different reproductive barriers on species or population isolation may vary in different stages of speciation depending on evolutionary forces acting within species and through species interactions. Genetic incompatibilities between interacting species are expected to reinforce prezygotic barriers in sympatric populations and create character displacement between conspecific populations living within and outside the area of sympatry. The outcome of reinforcement has been suggested to be affected by the strength of postzygotic barriers, the history of species coexistence, and the impact of species abundancies on females discrimination against heterospecific males. We tested these predictions in Drosophila montana and Drosophila flavomontana populations from different geographic regimes. All barriers between D. montana females and D. flavomontana males were extremely strong, while in the reciprocal cross postzygotic isolation was less effective and the target of reinforcement varied according to population type. In long-established sympatric populations, where D. flavomontana is abundant, reinforcement targeted sexual isolation, and in populations, where this species is a new invader and rare, reinforcement targeted postmating prezygotic barriers. Reinforcement of these barriers also created respective barriers between different D. flavomontana populations. These findings show that interspecies interactions have far-reaching effects on strengthening species barriers and promoting speciation.

evolutionary biology↗

bioRxiv2017

Destructive Disinfection Of Infected Brood Prevents Systemic Disease Spread In Ant Colonies

Social insects protect their colonies from infectious disease through collective defences that result in social immunity. In ants, workers first try to prevent infection of colony members. Here, we show that if this fails and a pathogen establishes an infection, ants employ an efficient multicomponent behaviour - \"destructive disinfection\" - to prevent further spread of disease through the colony. Ants specifically target infected pupae during the pathogens non-contagious incubation period, relying on chemical sickness cues emitted by pupae. They then remove the pupal cocoon, perforate its cuticle and administer antimicrobial poison, which enters the body and prevents pathogen replication from the inside out. Like the immune system of a body that specifically targets and eliminates infected cells, this social immunity measure sacrifices infected brood to stop the pathogen completing its lifecycle, thus protecting the rest of the colony. Hence, the same principles of disease defence apply at different levels of biological organisation.

evolutionary biology↗