Biodiversity Data Journal :
Research Article
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Corresponding author: Rusko Petrov (rpetrov@greenbalkans.org)
Academic editor: Emilian Stoynov
Received: 05 Dec 2023 | Accepted: 26 Jan 2024 | Published: 16 Feb 2024
© 2024 Rusko Petrov, Dobri Yarkov, Nayden Chakarov
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Petrov R, Yarkov D, Chakarov N (2024) Genetic analysis of Saker Falcon (Falco cherrug) subspecies. Biodiversity Data Journal 12: e116889. https://doi.org/10.3897/BDJ.12.e116889
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Two subspecies of Saker Falcon are commonly accepted - Western (Falco cherrug cherrug) and Eastern (Falco cherrug milvipes), which are differentiated by their distribution range and phenotype. In Bulgaria, Western Saker Falcons are breeding ex situ in the Wildlife Rehabilitation and Breeding Centre, part of Green Balkans - Stara Zagora NGO, with the aim of restoring the nesting population of the species in the country and both Western and Eastern - in the Breeding Centre for Birds of Prey in Burgas for the purpose of sale for the needs of falconry in the country and abroad. In 2021, a total of 115 birds from the two breeding centres were sampled. The samples were analysed in Bielefeld University (Germany) at nine microsatellite loci. Structure analyses were performed to establish the optimal explanatory number of groups. We compared the putative genetic groups with the known/expected origin of falcons. A separation in two groups best explained the allelic variation between samples. Out of 68 Saker Falcons with putatively Eastern origin, 66 were ascribed to genetic group 2 and two falcons had unclear, mixed or hybrid genetic fingerprints. Out of 42 Sakers with putatively Western origin, 33 were ascribed to genetic group 1, seven to genetic group 2 and two individuals appeared to have a mixed signature of genetic groups 1 and 2 with dominating alleles of group 2. Five known hybrids were scored as mixed signature with dominating genetic cluster 2. This suggests that the two (Eastern and Western) populations of Saker Falcon origin suggested by the subspecies' definitions are also adequate to be considered in breeding programmes. Genetic cluster 1 might represent the ancestral alleles shared with other falcons, while specific novel alleles allow the discrimination of secured Eastern Sakers (group 2), while these populations may be occasionally invaded by individuals from the west.
birds of prey, captive breeding, microsatellites, Falco cherrug cherrug, Falco cherrug milvipes
Since the first taxonomic description of the falcons in 1834 by British zoologist John Edward Gray, various scientists have defined a different number of Saker Falcon (Falco cherrug) subspecies (
Despite the lack of evidence for subspecies differentiation, the phenotypic diversity of a species arguably ought to be protected in any case (
In 2021, we sampled 115 falcons - 68 putatively Eastern Saker Falcons, 42 putatively Western and five known hybrids. All birds from the two facilities - WRBC and BCBP, were examined by a veterinary physician upon blood collection and were determined to be clinically healthy. We collected 0.1 ml of whole blood from either left or right basilic vein (Vena cutanea ulnaris superficialis) of all specimens tested. We immediately placed the blood into Eppendorf collection tubes of 1.5 ml volume containing 1 ml 90% alcohol. We used 3 ml syringes with 23G needles.
In 2022, these 115 samples of Saker Falcons were analysed at Bielefeld University, Germany at nine microsatellite loci - SSR11, SSR15, SSR45, SSR48, SSR53, SSR57, SSR63, SSR82 (
We compared the putative genetic groups with the known or expected origin of the falcons from the breeding facilities - the ones with incomplete pedigree information had been assigned to a group (Western or Eastern), based on history and appearance. Structure Harvester indicated that separation in two genetic clusters best explains the allelic variation between samples (Figs
Out of 68 Sakers with Eastern origin, 66 were ascribed to genetic group 2, two appeared to have mixed genetic signatures. Out of 42 Sakers with putatively Western origin, 33 were ascribed to genetic group 1, seven to genetic group 2 and two individuals appeared to have mixed signals from genetic groups 1 and 2 with a dominating signature of group 2. Five known hybrids (incl. one Lanner x Gyrfalcon - Falco biarmicus x Falco rusticolus) were scored as mixes with dominating genetic cluster 2 (Table
We found a segregation of Saker Falcon microsatellite alleles into two genetic clusters. This corresponds both to the expected and conservatively described separation of the species into two main subspecies, as well as to the putative origin/heritage of most of the sampled birds which have been bred in captivity over several generations.
Our results, showing two genetic clusters of Sakers, resonate both with morphology-based literature and subspecies descriptions. Importantly, almost 80% of the putatively Western-origin falcons were ascribed to a separate cluster, while more than 95% of the putative Eastern-originating birds segregated into another cluster. The latter cluster also included hybrids and a hybrid of other hierofalcons. This may indicate that this western cluster includes more ancestral alleles which are also shared with related species, possibly through interbreeding. In contrast, the eastern subspecies appears to be a branch with more derived alleles with possibly more recent origination. This hypothesis is in line with the “out of Africa” origin that has been suggested by other authors (
Importantly, our findings should not be interpreted as a lack of evidence for the existence of another two separate subspecies - F. c. coatsi, found in the plains of Transcaspia to eastern Uzbekistan and southern Kazakhstan and F. c. hendersoni, found in the Pamir Mountains east to the Tibetan Plateau, as described in the latest version of the Clements Checklist of Birds of the World (
In conclusion, as few as nine microsatellites were sufficient to recover the genetic segregation of Eastern and Western Saker Falcons. These two subspecies and associated morphologies should, therefore, be certainly considered during breeding programmes aimed at releasing birds into the wild in order to preserve genetic diversity without causing unnecessary interbreeding and disruption of potential locally-adapted alleles of functional genes. Thus, whenever doubts about the pedigree or origin of Saker Falcons in a breeding stock exist, these should be clarified through additional genetic fingerprinting.
The authors express gratitude to the funders of project “Saker Falcon reintroduction in Bulgaria” - the Mohamed Bin Zayed Raptor Conservation Fund (UAE) and Armeec JSC (Bulgaria), to Plamen Paskalev (BCBP) and to the employees and volunteers of the WRBC who assisted in obtaining the samples.