Schweiger, Susan
[VerfasserIn]
;
Olsson, Lennart
[AkademischeR BetreuerIn];
Müller, Hendrik
[AkademischeR BetreuerIn];
Kerney, Ryan
[AkademischeR BetreuerIn]Friedrich-Schiller-Universität Jena
Anmerkungen:
Kumulative Dissertation, enthält Zeitschriftenaufsätze
Tag der Verteidigung: 15.07.2022
Zusammenfassungen in deutscher und englischer Sprache
Beschreibung:
Although the majority of frogs and toads reproduce in bodies of water, there are trends towards an increasingly terrestrial reproduction in several lineages including in the sub-Saharan frog family Arthroleptidae (Afrobatrachia). Biphasic, fully aquatic species of Arthroleptidae all inhabit streams showing a highly specialized and robust cranial skeleton very different from tadpoles of their semiaquatic relatives in this group. Because direct development is associated with the loss of many of those typical larval features, it has been generally assumed that the tadpole was completely excised from the ontogeny of direct developing frogs. This idea is controversial and has led to different views about the tadpole as a developmental module, the role of metamorphosis and the evolutionary origin of the anuran larva. To help in a critical appraisal of these hypotheses, this study provides a detailed description of the direct developing African Squeaker frogs (Arthroleptis wahlbergii and A. xenodactyloides, Arthroleptidae, Afrobatrachia). The results are compared to closely related species exhibiting a more ancestral (e.g. biphasic) life history as well as to other non-related direct developing species. In this thesis it is shown that direct development is not invariably linked to a complete loss of larval features and that metamorphic changes correlate with thyroid gland activity. It is supposed that the tadpole cannot be viewed as a module that can either appear or disappear during evolutionary development. In contrast, the tadpole should be viewed as an evolutionary meta-module composed of many different developmental sub-modules. Different combinations of present and absent developmental sub-modules seem to underlie evolution of ‘similar’ direct developmental patterns in distantly related frogs. This indicates that a complete terrestrial development might have evolved in different ways.