Research

Cooperative breeding is a reproductive system where one or more than one individual help the breeding pair raising the offspring. Helpers can be offspring of the last year or unrelated individuals. Basic approaches trying to explain this behaviour imply ecological constraints making “help” the better option rather than investing in own offspring as well as life history traits predisposing species to this kind of behaviour.

Parrots are particularly pre-adapted to evolve a cooperative breeding system owing to their long life span and low mortality. However, until now this behaviour has been seldom observed in parrots. My study system, the El Oro Parakeet (Pyrrhura orcesi), is an endangered, non-territorial parrot inhabiting Southern and Midwestern Ecuador. Former observations in the Buenaventura Reserve (owned by the Fundación Jocotoco) have shown that these birds live in stable flocks of up to 3-15 individuals whole year round with every flock member apparently contribute to breeding activities.

First aim of my study will be to investigate the genetic system of the flocks of Buenaventura Reserve e.g. genetic relationship and sex ratio by means of microsatellite markers. The genetic relationships between individuals will be compared to behavioural observations gathered during breeding season. We experimentally manipulate the possible constraint of a limited nest site availability by implementing an artificial nest box scheme at Buenaventura Reserve. This implementation will reveal the influence of a critical ecological factor on the social organisation of that species. Skewed sex ratio is a further likely ecological constraint which will be examined by genetic analyses. The next step will be to compare the population of Buenaventura to other El Oro Parakeet populations in terms of migration and gene flow connecting populations. By comparing differences between habitats and habitat fragmentation I intend to identify the importance of regionally acting ecological constraints on the evolution and plasticity of the cooperative breeding system.

The El Oro Parakeet is classified as an endangered parakeet species with an estimated population size of <1000 individuals. The social organisation of a cooperative breeding system additionally decreases the effective population size, and it can facilitate inbreeding. Therefore I will analyse the gene flow among populations to assess the degree of isolation and the risk of habitat fragmentation for this species and the genetic diversity within populations to determine their potential for long-term survival.

The genetic study will be done in cooperation with PD Dr. Gernot Segelbacher (Department of Wildlife Ecology, University of Freiburg). My work is funded by the Volkswagen Stiftung.

Topic of Diploma thesis:

Phylogeography and population genetics of the burrowing parrot
(Cyanoliseus patagonus)

The burrowing parrot (Cyanoliseus patagonus) is a formerly common parrot species of Argentina and Chile.

One special feature of this parakeet species is its breeding behaviour. The species is monogamous, and couples live in colonies up to several thousand individuals (e.g. El Condor: greatest known parrot colony of the world). At this time they require vertical sand-, lime- or earthcliffs where they dug nest tunnels which are up to three meters long.

The burrowing parrot feeds mainly on wild seeds and fruits, nevertheless it is officially considered as agricultural pest and therefore suffers from hunting by farmers.

Further problems emerge from fragmentation and decline of their habitats as well as from pet trade. The UNEP-WCMC (United Nations Environment Programme – World Conservation Monitoring Centre) states a number of 63500 exported individuals in the years 1997-2005.

By morphological evidence there are four subspecies related to the burrowing parrot. Three of them living from north to south Patagonia: C.p.patagonus at central to southeast Argentina, C.p.andinus at northwest of Argentina and C.p.conlara from the west to central Argentina. While C.p. conlara is often just considered as hybrid of C.p. patagonus and C.p.andinus. The fourth subspecies C.p.bloxami, inhabited at the centre of Chile, lives geographical isolated from the other subspecies.

In spite of the threats mentioned above and the uncertainty of the status of the different subspecies, the last time the conservation status and the phylogenetic history of the burrowing parrot has been analyzed was in the early 1980´s.

The analyses of phylogeography and genetic differentiation could not only provide important information on the taxonomical and historical relationship between subspecies, but also about the conservation status of population (i.e. conservation unit) and their role in conserving gene flow and genetic diversity between widespread populations.

Beside, the genetic diversity, as key facet of conservation biology, ought to point out the viability of the populations and their ability to face changes in their environment, thus their ability to respond to selection.

One aspect of my diploma thesis is to determine the phylogeograhic and historical relationship of the Cyanoliseus subspecies, especially of the allopatric subspecies C. p. bloxami, by means of mitochondrial DNA sequence comparison (parts of the Cytochrome b, Cytochrome Oxidase 1 and ATPase 8/9 genes).

Furthermore genetic differentiation and genetic diversity in and between the subspecies and their populations should be detected by mtDNA sequence and microsatellite analyses.

The genetic information needed for this study is gained from moulted feathers from several colonies in Argentina and Chile.