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Tobler

Fakultäten » Mathematisch-naturwissenschaftliche Fakultät » Evolutionsbiologie und Umweltwissenschaften, Institut für » Ecology & Environment » Prof. Dr. Heinz-Ulrich Reyer (emeritiert) » Tobler

Completed research project

Title / Titel

Habitat deterioration, population structure, genetic diversity and infectious disease: A holistic view on population declines

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Abstract (PDF, 14 KB)

Summary / Zusammenfassung

This study will address an important question in conservation biology: Can genetic factors and an emerging infectious disease interact to cause population declines and local extinctions? Can these factors, alone or acting in concert, be more important than habitat loss and/or deterioration?
Many studies have addressed the effect of habitat loss and degradation on extinction but only a handful of studies asked whether genetic deterioration caused extinctions (e.g. Smith et al. 2006). Even fewer studies explored the role of emerging infectious diseases on extinction (but see Spielman et al. 2004b, but see Frankham 2005). None has asked whether there is an interaction between genetics and disease on the risk of extinction. This is surprising given the fact that it is well known that genetics strongly affect disease prevalence in many species (Keller and Waller 2002) and that interactions between stressors causing extinctions are the rule rather than the exception (Blaustein and Kiesecker 2002).
I will study a likely interaction between genetic diversity and an emerging infectious disease as the cause of declines in an amphibian, a group of vertebrates that is undergoing dramatic declines globally. An amphibian model system is well suited for such a project because (i) emerging infectious diseases (e.g. chytridiomycosis) contribute to global amphibian declines (e.g. Berger et al. 1998, Briggs et al. 2005, Lips et al. 2006, Pounds et al. 2006) and (ii) (molecular) genetic diversity is known to correlate to susceptibility to disease (Pearman and Garner 2005).
The goals of this project are
1) to determine the habitat-related factors and metapopulation factors that control the distribution and decline of the midwife toad;
2) to determine whether habitat-related factors and metapopulation factors affect the genetic diversity of the midwife toad;
3) to determine whether genetic diversity affects population viability through enhanced fitness; and
4) to determine the interplay between habitat factors, metapopulation factors, genetic structure and an emerging disease on the extinction probability of local populations of the midwife toad.
Alytes obstetricans, the common midwife toad, represents an ideal study system to address the question how genetic diversity is linked to population structure and whether genetic diversity affects disease prevalence and ultimately local extinction. Firstly, Alytes obstetricans in Switzerland is supposed to feature metapopulation structure that may be disrupted in intensively exploited areas (Hanski and Ovaskainen 2000, Kraaijeveld-Smit et al. 2005). Secondly, it faces two range edges, an altitudinal and a longitudinal one, where genetic variation is often lower (Garner et al. 2004). Thirdly, Alytes obstetricans is highly susceptible to chytridiomycosis (Bosch et al. 2001).

Keywords / Suchbegriffe

amphibians, global amphibian decline, Alytes obstetricans, chytridiomycosis, habitat loss, fragmentation, population structure, conservation

Project leadership and contacts /
Projektleitung und Kontakte

dipl. Zool. Ursina Tobler (Project Leader)	ursina.tobler@ieu.uzh.ch
Dr. Benedikt Schmidt	benedikt.schmidt@ieu.uzh.ch
Prof. Dr. Heinz-Ulrich Reyer	uli.reyer@ieu.uzh.ch