Name: Iago Silva Ornéllas
Type: MSc dissertation
Publication date: 20/02/2018
Advisor:
Name |
Role |
|---|---|
| Leonora Pires Costa | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Carlos Frederico Duarte da Rocha | External Examiner * |
| Cecília Waichert Monteiro | Internal Alternate * |
| Leonora Pires Costa | Advisor * |
| Rodrigo Barbosa Ferreira | External Alternate * |
| Sarah Maria Vargas | Internal Examiner * |
Summary: ABSTRACT
The use of islands for studies of evolutionary events has brought important answers for the
understanding of processes caused by population isolation and colonization by few founding
individuals. However, most of these results were observed on oceanic islands, which due to their
formation have extreme characteristics for these factors (isolation and founding effect). In continental
islands, the theory of island biogeography is less applied, mainly because the short distance to the
continent and its formation process. Their type of formation and proximity to the mainland generate
appearance and permanence of species in the islands that would be incapable of effectively dispersing
through the marine environment. Amphibians are intolerant to saline environments and high
temperatures, being their inability to be dispersed through marine environments well accepted. Thus,
the presence of anurans in oceanic islands is an extremely rare event, but common in continental
islands. The existence of frogs in continental islands is attributed to a vicarious event during the
elevation of the ocean that caused the formation of the island. We examined the species Thoropa
miliaris and Adenomera marmorata that are present both in the continental islands and in the
continental coastal portion. We used the resident island pollution of Ilha Grande on the south coast of
Rio de Janeiro and several samples from the continent to understand the processes of isolation and
colonization of the same. Through molecular analyzes with mitochondrial markers 16s and Nd2, we
elucidate information about the effects of isolation on the population, the possibility of migratory
events and whether island colonization was due to a vicarious or dispersive event. The loss of genetic
diversity was visualized in both species, being compatible with isolated animals in islands, as already
reported in other studies. T. miliaris behaved as expected for an anuran unable to be dispersed by
marine environment, showing high divergence with the coastal population and migration tending to
zero, with separation of the populations dating to the last great rise in sea level. However, A.
marmorata presented results indicating a high migratory rate and a recent colonization of the island,
compatible with events of colonization by dispersion.
Key words: Amphibians, insular, populations, migration and vicariance
