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Population ecology of the yellow-bellied toad (Bombina variegata) at the northern range margin: Focusing on demography and genetics

  • Amphibian populations are declining worldwide for multiple reasons such as habitat destruction and climate change. An example for an endangered European amphibian is the yellow-bellied toad Bombina variegata. Populations have been declining for decades, particularly at the northern and western range margin. One of the extant northern range centres is the Westerwald region in Rhineland-Palatinate, Germany. To implement informed conservation activities on this threatened species, knowledge of its life-history strategy is crucial. This study therefore focused on different developmental stages to test predictions of life-history theory. It addressed (1) developmental, (2) demographic and (3) genetic issues of Bombina variegata as a model organism: (1) Carry-over effects from larval environment to terrestrial stages and associated vulnerability to predators were investigated using mesocosm approaches, fitness tests and predation trials. (2) The dynamics and demography of B. variegata populations were studied applying a capture-mark-recapture analysis and skeletochronology. The study was complemented through (3) an analysis of genetic diversity and structuring of B. variegata populations using 10 microsatellite loci. In order to reveal general patterns and characteristics among B. variegata populations, the study focused on three geographical scales: local (i.e. a former military training area), regional (i.e. the Westerwald region) and continental scale (i.e. the geographical range of B. variegata). The study revealed carry-over effects of larval environment on metamorph phenotype and behaviour causing variation in fitness in the early terrestrial stage of B. variegata. Metamorph size and condition are crucial factors for survival, as small-sized individuals were particularly prone to predator attacks. Yellow-bellied toads show a remarkable fast-slow continuum of the life-history trait longevity. A populations’ position within this continuum may be determined by local environmental stochasticity, i.e. an extrinsic source of variation, and the efficiency of chemical antipredator protection, i.e. an intrinsic source of variation. Extreme longevity seems to be an exception in B. variegata. Senescence was absent in this study. Weather variability affected reproductive success and thus population dynamics. The dispersal potential was low and short-term fragmentation of populations caused significant genetic differentiation at the local scale. Long-term isolation resulted in increased genetic distance at the regional scale. At the continental scale, populations inhabiting the marginal regions were deeply structured with reduced allelic richness. As consequence of environmental changes, short-lived and isolated B. variegata populations at the range margin may face an increased risk of extinction. Conservation measures should thus improve the connectivity among local populations and reinforce annual reproductive success. Further research on the intraspecific variation in B. variegata skin toxins is required to reveal potential effects on palatability and thus longevity.

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Author:Alena Marcella Hantzschmann
Referee:Ulrich Sinsch, Heike Pröhl
Document Type:Doctoral Thesis
Date of completion:2020/06/16
Date of publication:2020/06/18
Publishing institution:Universität Koblenz, Universitätsbibliothek
Granting institution:Universität Koblenz, Fachbereich 3
Date of final exam:2020/05/29
Release Date:2020/06/18
Tag:Demographie; Gelbbauchunke; Genetik; Habitatfragmentierung; Klima; Langlebigkeit; Naturschutzmanagement; Rheinland-Pfalz; Yellow-bellied toad
Bombina variegata; Carry-over effects; Climate; Conservation; Demography; Fast-slow continuum; Genetics; Habitat Fragmentation; Life history; Longevity; Rhineland-Palatinate
GND Keyword:Gelbbauchunke
Number of pages:80
Ohne die enthaltenen Zeitschriftenaufsätze.
Institutes:Fachbereich 3 / Institut für Integrierte Naturwissenschaften / Institut für Integrierte Naturwissenschaften, Abt. Biologie
Licence (German):License LogoEs gilt das deutsche Urheberrecht: § 53 UrhG