@phdthesis{Sammler2012,
  author    = {Sammler, Svenja},
  title     = {Molecular evolution and conservation genetics in the two Philippine hornbill species Aceros waldeni and Penelopides panini},
  address   = {Potsdam},
  pages     = {105 S.},
  year      = {2012},
  language  = {en}
}
@phdthesis{SammlerKetmaierHavensteinetal.2012,
  author    = {Sammler, Svenja and Ketmaier, Valerio and Havenstein, Katja and Krause, Ulrike and Curio, Eberhard and Tiedemann, Ralph},
  title     = {Mitochondrial control region I and microsatellite analyses of endangered Philippine hornbill species (Aves; Bucerotidae) detect gene flow between island populations and genetic diversity loss},
  doi       = {10.1186/1471-2148-12-203},
  year      = {2012},
  language  = {en}
}
@article{SammlerKetmaierHavensteinetal.2012,
  author    = {Sammler, Svenja and Ketmaier, Valerio and Havenstein, Katja and Krause, Ulrike and Curio, Eberhard and Tiedemann, Ralph},
  title     = {Mitochondrial control region I and microsatellite analyses of endangered Philippine hornbill species (Aves; Bucerotidae) detect gene flow between island populations and genetic diversity loss},
  series = {BMC evolutionary biology},
  volume    = {12},
  journal   = {BMC evolutionary biology},
  number    = {25},
  publisher = {BioMed Central},
  address   = {London},
  issn      = {1471-2148},
  doi       = {10.1186/1471-2148-12-203},
  pages     = {14},
  year      = {2012},
  abstract  = {Background: The Visayan Tarictic Hornbill (Penelopides panini) and the Walden's Hornbill (Aceros waldeni) are two threatened hornbill species endemic to the western islands of the Visayas that constitute - between Luzon and Mindanao - the central island group of the Philippine archipelago. In order to evaluate their genetic diversity and to support efforts towards their conservation, we analyzed genetic variation in similar to 600 base pairs (bp) of the mitochondrial control region I and at 12-19 nuclear microsatellite loci. The sampling covered extant populations, still occurring only on two islands (P. panini: Panay and Negros, A. waldeni: only Panay), and it was augmented with museum specimens of extinct populations from neighboring islands. For comparison, their less endangered (= more abundant) sister taxa, the Luzon Tarictic Hornbill (P. manillae) from the Luzon and Polillo Islands and the Writhed Hornbill (A. leucocephalus) from Mindanao Island, were also included in the study. We reconstructed the population history of the two Penelopides species and assessed the genetic population structure of the remaining wild populations in all four species. Results: Mitochondrial and nuclear data concordantly show a clear genetic separation according to the island of origin in both Penelopides species, but also unravel sporadic over-water movements between islands. We found evidence that deforestation in the last century influenced these migratory events. Both classes of markers and the comparison to museum specimens reveal a genetic diversity loss in both Visayan hornbill species, P. panini and A. waldeni, as compared to their more abundant relatives. This might have been caused by local extinction of genetically differentiated populations together with the dramatic decline in the abundance of the extant populations. Conclusions: We demonstrated a loss in genetic diversity of P. panini and A. waldeni as compared to their sister taxa P. manillae and A. leucocephalus. Because of the low potential for gene flow and population exchange across islands, saving of the remaining birds of almost extinct local populations - be it in the wild or in captivity - is particularly important to preserve the species' genetic potential.},
  language  = {en}
}
@misc{SammlerKetmaierHavensteinetal.2017,
  author    = {Sammler, Svenja and Ketmaier, Valerio and Havenstein, Katja and Krause, Ulrike and Curio, Eberhard and Tiedemann, Ralph},
  title     = {Mitochondrial control region I and microsatellite analyses of endangered Philippine hornbill species (Aves; Bucerotidae) detect gene flow between island populations and genetic diversity loss},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401108},
  pages     = {14},
  year      = {2017},
  abstract  = {Background: The Visayan Tarictic Hornbill (Penelopides panini) and the Walden's Hornbill (Aceros waldeni) are two threatened hornbill species endemic to the western islands of the Visayas that constitute - between Luzon and Mindanao - the central island group of the Philippine archipelago. In order to evaluate their genetic diversity and to support efforts towards their conservation, we analyzed genetic variation in similar to 600 base pairs (bp) of the mitochondrial control region I and at 12-19 nuclear microsatellite loci. The sampling covered extant populations, still occurring only on two islands (P. panini: Panay and Negros, A. waldeni: only Panay), and it was augmented with museum specimens of extinct populations from neighboring islands. For comparison, their less endangered (= more abundant) sister taxa, the Luzon Tarictic Hornbill (P. manillae) from the Luzon and Polillo Islands and the Writhed Hornbill (A. leucocephalus) from Mindanao Island, were also included in the study. We reconstructed the population history of the two Penelopides species and assessed the genetic population structure of the remaining wild populations in all four species. Results: Mitochondrial and nuclear data concordantly show a clear genetic separation according to the island of origin in both Penelopides species, but also unravel sporadic over-water movements between islands. We found evidence that deforestation in the last century influenced these migratory events. Both classes of markers and the comparison to museum specimens reveal a genetic diversity loss in both Visayan hornbill species, P. panini and A. waldeni, as compared to their more abundant relatives. This might have been caused by local extinction of genetically differentiated populations together with the dramatic decline in the abundance of the extant populations. Conclusions: We demonstrated a loss in genetic diversity of P. panini and A. waldeni as compared to their sister taxa P. manillae and A. leucocephalus. Because of the low potential for gene flow and population exchange across islands, saving of the remaining birds of almost extinct local populations - be it in the wild or in captivity - is particularly important to preserve the species' genetic potential.},
  language  = {en}
}
@misc{SammlerKetmaierHavensteinetal.2013,
  author    = {Sammler, Svenja and Ketmaier, Valerio and Havenstein, Katja and Tiedemann, Ralph},
  title     = {Intraspecific rearrangement of duplicated mitochondrial control regions in the luzon tarictic hornbill penelopides manillae (Aves: Bucerotidae)},
  series = {Journal of molecular evolution},
  volume    = {77},
  journal   = {Journal of molecular evolution},
  number    = {5-6},
  publisher = {Springer},
  address   = {New York},
  issn      = {0022-2844},
  doi       = {10.1007/s00239-013-9591-y},
  pages     = {199 -- 205},
  year      = {2013},
  abstract  = {Philippine hornbills of the genera Aceros and Penelopides (Bucerotidae) are known to possess a large tandemly duplicated fragment in their mitochondrial genome, whose paralogous parts largely evolve in concert. In the present study, we surveyed the two distinguishable duplicated control regions in several individuals of the Luzon Tarictic Hornbill Penelopides manillae, compare their characteristics within and across individuals, and report on an intraspecific mitochondrial gene rearrangement found in one single specimen, i.e., an interchange between the two control regions. To our knowledge, this is the first observation of two distinct mitochondrial genome rearrangements within a bird species. We briefly discuss a possible evolutionary mechanism responsible for this pattern, and highlight potential implications for the application of control region sequences as a marker in population genetics and phylogeography.},
  language  = {en}
}
@article{SammlerBleidornTiedemann2011,
  author    = {Sammler, Svenja and Bleidorn, Christoph and Tiedemann, Ralph},
  title     = {Full mitochondrial genome sequences of two endemic Philippine hornbill species (Aves: Bucerotidae) provide evidence for pervasive mitochondrial DNA recombination},
  series = {BMC genomics},
  volume    = {12},
  journal   = {BMC genomics},
  number    = {2},
  publisher = {BioMed Central},
  address   = {London},
  issn      = {1471-2164},
  doi       = {10.1186/1471-2164-12-35},
  pages     = {10},
  year      = {2011},
  abstract  = {Background: Although nowaday it is broadly accepted that mitochondrial DNA (mtDNA) may undergo recombination, the frequency of such recombination remains controversial. Its estimation is not straightforward, as recombination under homoplasmy (i.e., among identical mt genomes) is likely to be overlooked. In species with tandem duplications of large mtDNA fragments the detection of recombination can be facilitated, as it can lead to gene conversion among duplicates. Although the mechanisms for concerted evolution in mtDNA are not fully understood yet, recombination rates have been estimated from "one per speciation event" down to 850 years or even "during every replication cycle". Results: Here we present the first complete mt genome of the avian family Bucerotidae, i.e., that of two Philippine hornbills, Aceros waldeni and Penelopides panini. The mt genomes are characterized by a tandemly duplicated region encompassing part of cytochrome b, 3 tRNAs, NADH6, and the control region. The duplicated fragments are identical to each other except for a short section in domain I and for the length of repeat motifs in domain III of the control region. Due to the heteroplasmy with regard to the number of these repeat motifs, there is some size variation in both genomes; with around 21,657 bp (A. waldeni) and 22,737 bp (P. panini), they significantly exceed the hitherto longest known avian mt genomes, that of the albatrosses. We discovered concerted evolution between the duplicated fragments within individuals. The existence of differences between individuals in coding genes as well as in the control region, which are maintained between duplicates, indicates that recombination apparently occurs frequently, i. e., in every generation. Conclusions: The homogenised duplicates are interspersed by a short fragment which shows no sign of recombination. We hypothesize that this region corresponds to the so-called Replication Fork Barrier (RFB), which has been described from the chicken mitochondrial genome. As this RFB is supposed to halt replication, it offers a potential mechanistic explanation for frequent recombination in mitochondrial genomes.},
  language  = {en}
}
@misc{SammlerBleidornTiedemann2017,
  author    = {Sammler, Svenja and Bleidorn, Christoph and Tiedemann, Ralph},
  title     = {Full mitochondrial genome sequences of two endemic Philippine hornbill species (Aves: Bucerotidae) provide evidence for pervasive mitochondrial DNA recombination},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400889},
  pages     = {10},
  year      = {2017},
  abstract  = {Background: Although nowaday it is broadly accepted that mitochondrial DNA (mtDNA) may undergo recombination, the frequency of such recombination remains controversial. Its estimation is not straightforward, as recombination under homoplasmy (i.e., among identical mt genomes) is likely to be overlooked. In species with tandem duplications of large mtDNA fragments the detection of recombination can be facilitated, as it can lead to gene conversion among duplicates. Although the mechanisms for concerted evolution in mtDNA are not fully understood yet, recombination rates have been estimated from "one per speciation event" down to 850 years or even "during every replication cycle". Results: Here we present the first complete mt genome of the avian family Bucerotidae, i.e., that of two Philippine hornbills, Aceros waldeni and Penelopides panini. The mt genomes are characterized by a tandemly duplicated region encompassing part of cytochrome b, 3 tRNAs, NADH6, and the control region. The duplicated fragments are identical to each other except for a short section in domain I and for the length of repeat motifs in domain III of the control region. Due to the heteroplasmy with regard to the number of these repeat motifs, there is some size variation in both genomes; with around 21,657 bp (A. waldeni) and 22,737 bp (P. panini), they significantly exceed the hitherto longest known avian mt genomes, that of the albatrosses. We discovered concerted evolution between the duplicated fragments within individuals. The existence of differences between individuals in coding genes as well as in the control region, which are maintained between duplicates, indicates that recombination apparently occurs frequently, i. e., in every generation. Conclusions: The homogenised duplicates are interspersed by a short fragment which shows no sign of recombination. We hypothesize that this region corresponds to the so-called Replication Fork Barrier (RFB), which has been described from the chicken mitochondrial genome. As this RFB is supposed to halt replication, it offers a potential mechanistic explanation for frequent recombination in mitochondrial genomes.},
  language  = {en}
}
@article{SammlerHavensteinTiedemann2012,
  author    = {Sammler, Svenja and Havenstein, Katja and Tiedemann, Ralph},
  title     = {Fourteen new microsatellite markers for the Visayan tarictic hornbill (Penelopides panini) and their cross-species applicability among other endangered Philippine hornbills},
  series = {Conservation genetics resources},
  volume    = {4},
  journal   = {Conservation genetics resources},
  number    = {2},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {1877-7252},
  doi       = {10.1007/s12686-011-9567-4},
  pages     = {435 -- 438},
  year      = {2012},
  abstract  = {Fourteen microsatellite markers were isolated and characterized for the endangered Visayan tarictic hornbill (Penelopides panini, Aves: Bucerotidae). In an analysis of 76 individuals, the number of alleles per locus varied from one to 12. Expected and observed heterozygosity ranged from 0.00 to 0.87 and from 0.00 to 0.89, respectively. All primers also amplify microsatellite loci in Luzon tarictic hornbill (Penelopides manillae), Mindanao tarictic hornbill (Penelopides affinis), the critically endangered Walden's hornbill (Aceros waldeni) and the near-threatened writhed hornbill (Aceros leucocephalus). Two loci which are monomorphic in P. panini were found polymorphic in at least one of the other species. These 14 new microsatellite markers specifically developed for two genera of Philippine hornbills, in combination with those already available for the hornbill genera Buceros and Bucorvus, comprise a reasonable number of loci to genetically analyse wild and captive populations of these and probably other related, often endangered hornbills.},
  language  = {en}
}