Conservation of the critically endangered frog Telmatobufo bullocki in fragmented temperate forests of Chile : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Albany, New Zealand
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Date
2015
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Massey University
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Abstract
Amphibians are currently facing several threats and are suffering severe population
declines and extinction worldwide. Telmatobufo bullocki (Anura: Calyptocephalellidae) is
one of the rarest and most endangered amphibian species in Chile's temperate forests. It is
the fifth most evolutionarily distinct and globally endangered (EDGE) amphibian in the
world, and one of the world's top 100 priority species for conservation (Zoological Society
of London, 2011).This stream-breeding frog is micro-endemic to the coastal Nahuelbuta
mountain range in central-south Chile (37°C - 38°50' S), a hot-spot for conservation. This area
has suffered severe loss and fragmentation of native forest, which has been replaced by
extensive commercial plantations of exotic pines and eucalyptus. Despite its potential
detrimental effects, the impact of native forest loss on this species has not been studied
before. Furthermore, few historical observations exist, and the ecology and behaviour of
the species is poorly known. In addition, current status and location of extant populations
are uncertain, which makes conservation and targeted habitat protection difficult.
Through the use of different approaches and modern conservation tools this thesis aims to
make a significant contribution to the conservation of T.bullocki and its habitat. Historical
and new locations were surveyed to identify extant populations. A distribution modeling
approach (i.e. Maxent) was used to infer the species’ distribution within Nahuelbuta,
generate a predictive habitat suitability map, identify important environmental
associations, and assess the impact of main environmental threats (i.e. native forest loss,
climate change).Field-based research (e.g. surveys, radio-tracking) was done to extend the
ecological and behavioural knowledge of the species (e.g. movement patterns and habitat
use), and identify critical aquatic and terrestrial habitat for protection (i.e. core habitat).
Mitochondrial and specifically developed microsatellite genetic markers were used to
measure levels of intra-specific genetic variability, define genetic population structure and
connectivity, infer evolutionary history (phylogeography), estimate effective population
size and detect demographic changes (e.g. bottlenecks). Finally, a landscape genetics
approach was used to relate landscape characteristics to contemporary patterns of gene
flow, and identify important landscape features facilitating (i.e. corridors) or hindering (i.e.
barriers) genetic connectivity between populations.
Telmatobufo bullocki was found in nine basins within Nahuelbuta, including historic and
new locations. Presence of T. bullocki was positively related to the amount of native
forests in the landscape. However, some populations persist in areas dominated by exotic
plantations. Some frogs were found living under mature pine plantation adjacent to native
forest, but no frogs were found in core plantation areas.T. bullocki makes extensive use of
terrestrial habitat adjacent to breeding streams during the post-breeding season, moving
up to 500 m away from streams. A core terrestrial habitat of at least 220 m from streams is
proposed for the protection of populations. Population genetics and phylogeography
revealed significant population structure. The northernmost and disjunct population of
Chivilingo is geographically and genetically isolated from all other sampled populations and
was identified as a separate evolutionary significant unit (ESU). The population of Los
Lleulles was also identified as a separate management unit, while the remaining
populations were grouped into two clusters forming a larger and more connected metaC
population. Connectivity within groups was high, suggesting individuals are able to
disperse between neighbouring basins. Levels of genetic diversity were not homogeneous,
and were lowest at Los Lleulles and highest at Caramávida. Results suggest disjunct
populations are at highest risk and should be prioritised for restoration and habitat
protection, while management of metaCpopulations should aim at maintaining and
improving connectivity among basins. Landscape genetic results identified streams and
riparian habitat as dispersal pathways, and least-cost-path analysis was used to identify a
potential connectivity network.
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Telmatobufo bullocki