Full text
| |
| Author(s): |
Luiz Gustavo de Almeida Pedroso
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Rio Claro. 2022-07-26. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro |
| Defense date: | 2022-06-13 |
| Advisor: | José Paulo Leite Guadanucci; Fabio Akashi Hernandes |
| Abstract | |
The specificity is a crucial aspect ruling host-symbiont interactions. It is usually linked to the symbiont's transmission potential, adaptation plasticity, and availability of compatible hosts. Despite its importance, specificity is still a complex subject in many host-symbiont systems, especially regarding their potential to emerge into new hosts. Feather mites (Astigmata: Analgoidea and Pterolichoidea) are examples of such highly specific symbionts. Because of their obligatory association and apparent low mobility properties, their transmission occurs by intimate contact between avian hosts, which usually receive their first set of mites through vertical transmission from parents to offspring. This vertical transmission is believed to be a key factor sustaining the high host specificity in feather mites, as many mite species are found solely on closely related hosts. Systems disrupting this transmission pattern offer valuable opportunities to investigate its connections with host specificity and other aspects of feather mite biology, such as geographic distribution. Here enters the shiny cowbird (Molothrus bonariensis), a brood parasitic bird that relies on other passerines to rear their chicks, preventing the usual vertical transmission of feather mites. It is no surprise that this system has never been studied as the knowledge of feather mites in the Neotropical region is still incipient. Therefore, here we investigate the feather mite fauna on the shiny cowbird and their most common hosts in Brazil. The present thesis is divided into two main subjects: a first part focused on recording the feather mites fauna from the shiny cowbird and understanding their relationship with aspects of host specificity and transmission; and a second part focused on the geographic distribution of feather mites in Brazil, also connecting it to host specificity properties. By multiple lines of evidence (abundance, prevalence, phylogenetic, and co-phylogenetic), it was possible to differentiate specific-to-cowbird mites from mites acquired from their foster parents and estimate rates of vertical and horizontal transmission in this system. Even lacking vertical intraspecific transmission, the shiny cowbird presented a diverse feather mite fauna composed of five species in five genera. This specific fauna is only transmitted horizontally, which occurs at a rate three times higher than vertical transmissions. Estimating for other systems, the vertical transmission of feather mites is important for a primary acquisition of these symbionts, while the horizontal transmission is likely the main responsible for the dispersal of these mites on host populations. Regarding their distribution, modularity analyzes identified patterns of distribution for the non-specific mites on shiny cowbirds explained by their preferences in host usage in different regions. It was also possible to corroborate the efficiency of horizontal transmissions in keeping their specific mite fauna evenly distributed in Brazil. Finally, patterns of the geographic distribution of feather mites on different host populations are shown in Brazil, with potential cryptic species. New feather mite species were also described. The novelties in the present work collaborate to understand the dispersion and organization of feather mites on their hosts, acknowledging a higher efficiency of horizontal transmissions than expected in these apparently low mobile symbionts. Our data also reinforce the importance of the host specificity as the limiting factor for the distribution and the colonization of new hosts by feather mites. (AU) | |
| FAPESP's process: | 16/11671-1 - Geographic distribution, horizontal transfer and speciation in feather mites (Astigmata) in Brazil |
| Grantee: | Luiz Gustavo de Almeida Pedroso |
| Support Opportunities: | Scholarships in Brazil - Doctorate |