Research Article |
Corresponding author: Petr Hrabina ( xhrabina@mendelu.cz ) Academic editor: Alessio Iannucci
© 2023 Petr Hrabina, Ludmila Pernerová, Josef Suchomel, Jan Robovský.
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:
Hrabina P, Pernerová L, Suchomel J, Robovský J (2023) Utility of cytochrome c oxidase I for the deciphering of unstable phylogeny and taxonomy of gorals, genus Nemorhaedus Hamilton Smith, 1827 (Bovidae, Ovibovina). ZooKeys 1181: 81-110. https://doi.org/10.3897/zookeys.1181.108019
|
Gorals represent ungulate mammals of the Palearctic and Indo-Malayan realms that face habitat destruction and intense hunting pressure. Their classification has been the subject of various (mainly genetic) assessments in the last decade, but some results are conflicting, hampering some conservation-based decisions. Genetic sampling of gorals has increased considerably in recent years, at least for mitochondrial (mt) DNA. Results based on two mt genes (cytochrome b and the D-loop) are currently available. Still, the utility of cytochrome oxidase subunit I remains unanalysed, even though it belongs among the gene markers that enable a correct species identification in mammals. This study examines phylogenetic relationships and species delimitation in gorals using all currently available cytochrome oxidase subunit I sequences, including the not yet analysed goral population from Pakistan. Our results of various phylogenetic approaches, such as maximum parsimony, likelihood and Bayesian inference, and exploration of species boundaries via species delimitation support the validity of six species of goral, namely N. baileyi, N. caudatus, N. cranbrooki, N. evansi, N. goral, and N. griseus. This result accords well with results based on other mt genes, especially the cytochrome b from the highly exhaustive data sampling. Our study also summarises common sources of errors in the assessment of goral phylogeny and taxonomy and highlights future priorities in understanding goral diversification.
COI, mitochondrion, Naemorhedus, voucher specimen
Gorals are elusive herbivore mammals that occupy the mixed feeder niche in the Palearctic and Indo-Malayan realms (
Gorals have already been the subject of some conservation-based population genetics studies (
It is worth noting that attempts to decipher goral phylogeny and species diversity are hampered by several complicated factors, as follows: relative phenotypic similarity of goral taxa; rarity of localised collection specimens (
Detailed information for all goral sequence included in this study. Species are arranged alphabetically by scientific name.
Species name | Accession Numbers | Provenance | marker available | Reference |
---|---|---|---|---|
N. baileyi | JN632663 | Yigong village, Linzhi City, Tibet, China | complete mitochondrion |
|
N. baileyi | KP203894 | Yigong village, Linzhi City, Tibet, China | complete mitochondrion |
|
N. caudatus | FJ469673 | South Korea | complete mitochondrion |
|
N. cranbrooki | MN853098 | Awadam village, Putao District, Myanmar | complete mitochondrion |
|
N. cranbrooki | MN853099 | Tala Htu village, Putao District, Myanmar | complete mitochondrion |
|
N. cranbrooki | MN853101 | Putao District, Myanmar | complete mitochondrion |
|
N. cranbrooki | MN853102 | Ziyadam village, Putao District, Myanmar | complete mitochondrion |
|
N. cranbrooki | MN853103 | Putao District, Myanmar | complete mitochondrion |
|
N. evansi | JN632664 | Chiang Mai Province, Thailand | complete mitochondrion |
|
N. evansi | MF155891 | Fanjingshan National Nature Reserve, Guizhou Province, China | complete mitochondrion |
|
N. evansi | MN853096 | Putao District, Myanmar | complete mitochondrion |
|
N. goral | OK244620 | Machiara National Park, Azad Jammu and Kashmir, Pakistan | complete COI gene | A. Naseem (The University of Sargodha, Pakistan) direct submission to GenBank |
N. goral | OK244621 | Machiara National Park, Azad Jammu and Kashmir, Pakistan | complete COI gene | A. Naseem (The University of Sargodha, Pakistan) direct submission to GenBank |
N. goral | OK244622 | Machiara National Park, Azad Jammu and Kashmir, Pakistan | complete COI gene | A. Naseem (The University of Sargodha, Pakistan) direct submission to GenBank |
N. griseus | FJ207532 | Central China | complete mitochondrion |
|
N. griseus | JX188255 | China | complete mitochondrion |
|
N. griseus | KF500173 | Wufeng Tujia Autonomous County, Hubei Province, China | complete mitochondrion |
|
N. griseus | KT878720 | Tangjiahe National Nature Reserve, Sichuan Province, China | complete mitochondrion |
|
N. griseus | MG591488 | Wutai County, Shanxi Province, China | complete mitochondrion |
|
N. griseus | MG865962 | western Sichuan Province, China | complete mitochondrion |
|
Concerning an imbalance between morphological and genetic revisions of gorals, although some authors have tried to compare taxa using morphological data (Suppl. material
Although some different phylogenetic relationships and affinities revealed by genetic or morphological studies seem to be contradictory, the contradictions arise only from taxa sampling and voucher (mis)identifications (Suppl. material
List of goral complete mitochondrial genomes revised by different sources.
Accession Numbers | Organism (as specified in GenBank) |
|
|
the present study | Data used for a revision |
---|---|---|---|---|---|
JN632664 | Nemorhaedus griseus | Nemorhaedus evansi | Nemorhaedus evansi | Nemorhaedus evansi | GD, PR, SGO |
MF155891 | Nemorhaedus griseus | Nemorhaedus evansi | Nemorhaedus evansi | Nemorhaedus evansi | GD, PR |
MG865962 | Nemorhaedus goral | Nemorhaedus griseus | Nemorhaedus griseus | GD, PR, SGO | |
MG591488 | Nemorhaedus goral | Nemorhaedus griseus | Nemorhaedus griseus | GD, PR, SGO | |
KT878720 | Nemorhaedus goral | Nemorhaedus griseus | Nemorhaedus griseus | GD, PR, SGO | |
JX188255 | Nemorhaedus goral | Nemorhaedus griseus | GD, PR | ||
MN853096 | Nemorhaedus evansi | hybrid between N. cranbrooki and N. evansi? | PF |
Considering all noted factors, especially the limited sampling and unstable phylogeny and taxonomy of gorals, they deserve further assessment, since their concise taxonomy might be helpful for further conservation actions in respect of international and national laws. The current study aims to inspect the utility of COI for both the detection of phylogenetic relationships among goral taxa and the inspection of diversification among available goral COI voucher specimens, using genetic distances and single-locus species delimitation.
Gorals seem to represent an ideal model for these aims among caprines due to the available taxon-population sampling (i.e., due to the highest available numbers of complete mitogenomes), their sedentary lifestyle, the philopatry of females (
Originally, we used 134 complete COI sequences (altogether 1545 bp) of gorals and other members of the tribe Caprini (according to
Considering similarities among goral species and some taxonomic inertia in this group during recent decades, all sequences were checked according to their localities using taxonomically sensitive sources (
The sequences were aligned using the MAFFT version 6 automatic multiple alignment programme for amino acid or nucleotide sequences (
Genetic distances were estimated based on Kimura’s two-parameter model (K2P) of substitutions in MEGA5 (
The dataset was examined using various approaches:
neighbour-joining (NJ),
maximum parsimony (MP),
maximum likelihood (ML) and
Bayesian inference methods (BI), respectively, within MEGA11 (
The observed ASDSF values of around 0.002–0.003 and effective sample sizes of MCCM per each run of at least around 1107 meet the criteria for recommended convergence thresholds according to
To assess nodal support, the bootstrapping with 250 replicates (i.e., within the recommended range by
To explore species boundaries in the COI ML and BI trees, we calculated several statistics using the Species Delimitation plugin (
The 134 COI sequences exhibited a significant number of variable sites, specifically 558 from all 1545 bp, of which 509 were parsimony informative. The dataset provided significant support for two goral groups, which are definable by their distribution: group I, comprising N. baileyi+N. cranbrooki+N. evansi, occupies the southeastern part of the goral range, whereas group II, comprising N. goral+N. caudatus+N. griseus, includes samples from Pakistan, Central China and South Korea (Figs
Goral group I exhibited the topology evansi+(baileyi+cranbrooki) consistently in all sorts of analyses (Figs
Furthermore, the relationships among goral taxa in group II were dependent on an analytical approach. Specifically, the NJ and ML analyses detected goral+(caudatus+griseus) topology (Figs
The single-locus species delimitation statistics provided in their combination a support for the distinctiveness of all putative species (Tables
Summary statistics from the Species Delimitation plugin of Geneious for Nemorhaedus species recovered in the Bayesian tree using data from COI. Species are arranged alphabetically by scientific name.
Species | Closest Species | Monophyletic? | Intra | Inter - Closest | Intra/Inter | P ID (strict) | P ID (liberal) | Av (MRCA-tips) | P (Randomly Distinct) | Clade Support | Rosenberg’s P(AB) |
---|---|---|---|---|---|---|---|---|---|---|---|
N. baileyi | N. cranbrooki | YES | 0.002 | 0.032 | 0.05 | 0.57 (0.42, 0.72) | 0.95 (0.8, 1.0) | 7.860E-4 | 0.05 | 1.00 | 0.02 |
N. caudatus | N. griseus | YES | 0.00E+00 | 0.035 | 0.00E+00 | 0.00E+00 (0.00E+00, 0.00E+00) | 0.96 (0.83, 1.00) | 0.00E+00 | NA | NA | 0.05 |
N. caudatus | N. griseus (eastern subclade) | YES | 0.00E+00 | 0.028 | 0.00E+00 | 0.00E+00 (0.00E+00, 0.00E+00) | 0.96 (0.83, 1.00) | 0.00E+00 | NA | NA | 0.1 |
N. cranbrooki | N. baileyi | YES | 0.002 | 0.032 | 0.06 | 0.90 (0.77, 1.00) | 0.97 (0.87, 1.0) | 9.303E-4 | 0.05 | 1.00 | 0.02 |
N. evansi | N. baileyi | YES | 0.010 | 0.063 | 0.16 | 0.69 (0.51, 0.86) | 0.92 (0.77, 1.0) | 0.0081 | 0.14 | 1.00 | 1.85E-03 |
N. goral | N. griseus | YES | 0.002 | 0.077 | 0.02 | 0.78 (0.60, 0.95) | 1.0 (0.85, 1.0) | 7.810E-4 | 0.05 | 1.00 | 0.17 |
N. goral | N. griseus (eastern subclade) | YES | 0.002 | 0.099 | 0.02 | 0.78 (0.61, 0.96) | 1.0 (0.86, 1.0) | 7.933E-4 | 0.05 | 1.00 | 0.01 |
N. griseus | N. caudatus | NO | 0.019 | 0.035 | 0.54 | 0.57 (0.45, 0.70) | 0.85 (0.75, 0.95) | 0.0117 | 0.05 | 0.90 | 0.05 |
Summary statistics from the Species Delimitation plugin of Geneious for Nemorhaedus species recovered in the maximum-likelihood tree using data from COI. Species are arranged alphabetically by scientific name.
Species | Closest Species | Monophyletic? | Intra | Inter - Closest | Intra/Inter | P ID (strict) | P ID (liberal) | Av (MRCA-tips) | P (Randomly Distinct) | Clade Support | Rosenberg’s P(AB) |
---|---|---|---|---|---|---|---|---|---|---|---|
N. baileyi | N. cranbrooki | YES | 8.00E-6 | 0.025 | 3.2E-4 | 0.59 (0.44, 0.74) | 0.98 (0.83, 1.0) | 4.000E-6 | 0.05 | 1.00 | 0.02 |
N. caudatus | N. griseus | YES | 0.00E+00 | 0.025 | 0.00E+00 | 0.00E+00 (0.00E+00, 0.00E+00) | 0.96 (0.83, 1.0) | 0.00E+00 | NA | NA | 0.05 |
N. cranbrooki | N. baileyi | YES | 2.73E-4 | 0.025 | 0.01 | 0.93 (0.80, 1.0) | 0.98 (0.88, 1.0) | 1.406E-4 | 0.05 | 1.00 | 0.02 |
N. evansi | N. baileyi | YES | 0.006 | 0.046 | 0.14 | 0.70 (0.52, 0.87) | 0.93 (0.78, 1.0) | 0.0056 | 0.81 | 1.00 | 1.85E-03 |
N. goral | N. griseus | YES | 1.06E-5 | 0.078 | 1.3E-4 | 0.79 (0.62, 0.97) | 1.0 (0.86, 1.0) | 6.666E-6 | 0.05 | 1.00 | 1.85E-03 |
N. griseus | N. caudatus | YES | 0.013 | 0.025 | 0.51 | 0.59 (0.47, 0.72) | 0.86 (0.76, 0.96) | 0.0078 | 0.07 | 0.50 | 0.05 |
Here we compare the statistics of species in much detail:
Larger values of intraspecific tree distances (see “Intra” in Tables
Uncorrected and K2P distances among goral species are shown in Table
Matrix of genetic distances (percent sequence divergence) within and among species of genus Nemorhaedus. Average uncorrected (p) distances among conspecific sequences are arrayed along the diagonal, interspecific p distances are below the diagonal, and Kimura two-parameter (K2P) distances are above the diagonal. Species are arranged alphabetically by scientific name.
N. baileyi | N. caudatus | N. cranbrooki | N. evansi | N. goral | N. griseus | N. griseus western group | N. griseus eastern group | |
---|---|---|---|---|---|---|---|---|
N. baileyi | 0.00 | 7.70 | 2.32 | 3.87 | 9.52 | 7.86 | 8.08 | 7.75 |
N. caudatus | 6.73 | – | 7.00 | 6.99 | 5.76 | 2.10 | 3.03 | 1.77 |
N. cranbrooki | 2.21 | 8.06 | 0.03 | 3.74 | 10.28 | 8.33 | 8.61 | 8.19 |
N. evansi | 3.60 | 8.02 | 3.49 | 0.60 | 10.11 | 8.29 | 8.46 | 8.21 |
N. goral | 8.09 | 6.43 | 8.62 | 8.52 | 0.00 | 5.11 | 4.08 | 5.63 |
N. griseus | 6.84 | 2.19 | 7.19 | 7.18 | 4.66 | 1.13 | – | – |
N. griseus western group | 7.02 | 2.88 | 7.42 | 7.32 | 3.79 | – | 0.4 | 1.8 |
N. griseus eastern group | 6.75 | 1.72 | 7.10 | 7.14 | 5.10 | – | 1.58 | 0.6 |
The phylogenetic consensus on two lines of gorals – baileyi–cranbrooki–evansi versus caudatus–goral–griseus (taxa ordered alphabetically) – obtained in this study is fully concordant with some other studies based on different mt genes or the whole mitogenomes (e.g.,
In terms of summarising various statistics relating to phylogenetic exclusivity, COI seems to support the distinctiveness of six goral taxa, specifically N. baileyi, N. caudatus, N. cranbrooki, N. evansi, N. goral and N. griseus. Our results exhibit a noticeable concordance with most attempts to revise gorals since 2005, especially with
All authors of goral assessments since 2000 (Suppl. material
Although the validity of N. goral is widely accepted because it was the first named species of the genus, it also represents the most complicated species from taxonomic and geographic perspectives. The first reason for this is that many authors still adopt the single-species concept in this genus first proposed by
Map of distribution range of grey and brown goral following two major zoogeographical concepts with consequences of their taxonomy. The black dots represent the type localities of the three available names for Himalayan taxa: N. bedfordi (Lydekker, 1905) (Dharamshala, Himachal Pradesh, India), N. goral (Hardwicke, 1825) (Kathmandu, Nepal) and N. hodgsoni Pocock, 1908 (Sikkim, India). The upper map shows a scheme where the distribution boundary between the two species is formed by the Sutlej River, Himachal Pradesh, India. N. bedfordi here represents a valid name for the western species, and the East Himalayan species is referred to as N. goral (see
The second described species, N. caudatus, is one of the best studied goral species due to the various scientific studies from many fields based mainly on the population from South Korea. It has been consensually recognised as a valid species in all taxonomic studies adopting both morphological and molecular approaches (e.g.,
All recent morphology-based revisions have recognised the existence of N. griseus (
It is also important to note that the genetic screening of COI nowhere near covers the entire distribution range of N. griseus. As the results of genotyping of mitochondrial fragments and microsatellite markers of nuclear DNA in animals from the northeastern limit of the species range, specifically from Songshan National Nature Reserve (Beijing) and Saihanwula National Nature Reserve (Inner Mongolia), suggest further increases in genetic distance (
While N. evansi was predominantly lumped with N. griseus-based morphological evidence,
With reference to
N. baileyi is one of the least studied species due to its remote, geographically restricted range and the almost complete absence of comparative material in world collections. The two sequences from our analyses both have a direct link to the breeding group in the Shanghai Zoo, which is currently the only holder of this species in captivity (
N. cranbrooki, as the latest goral taxa, described in 1961 by Hayman, has been predominantly synonymised with N. baileyi based on morphological evidence, but the molecular data presented by
Considering the genetic sampling of published studies and currently inspected available GenBank and Barcode of Life Data System sequences, we recommend further attention be paid to the following taxa and populations:
In summary, COI exhibited a good resolution for separation species, but it did not contain a strong resolving power in the case of phylogenetic relationships. Since it provides very similar results to those of other mitochondrial genes (cyt b and the D-loop) used in assessments of goral phylogeny and taxonomy, we recommend sequencing of the complete sequence of all three mt genes for degraded samples from collections and the field. If the sample is well preserved, sequencing of the complete mitochondrial genome is highly recommended. It is worth mentioning that gorals are believed to represent sedentary caprines, with a limited male-based dispersal (
Considering complicating factors in deciphering goral phylogeny and taxonomy (see Introduction), we fully agree with
Incidentally, authors should be aware that excessive lumping of threatened taxa may have disastrous consequences for the future conservation prospects of forgotten narrow endemic ungulate taxa (
Since we used data from the GenBank database, we would like to thank the enthusiastic and time-consuming work of all contributors of caprine sequences to the shared GenBank database. We would like to express our gratitude to the editor and to three referees for their critical reviews and very valuable suggestions, which greatly improved the final version of the manuscript. We are grateful to Anton Baer for the professional editing of the English.
The authors have declared that no competing interests exist.
No ethical statement was reported.
The project was supported by Mendel University in Brno through the Internal Grant Agency of the Faculty of AgriSciences (MENDELU AF-IGA-2018-tym004).
Conceptualization: JR, PH. Data curation: PH, JR. Formal analysis: PH, JR, LP. Funding acquisition: JR, JS. Investigation: PH, JR, LP. Methodology: PH, LP, JR. Project administration: JS. Resources: PH, JR. Software: JR. Supervision: JR, PH. Validation: JR. Visualization: PH. Writing – original draft: JR, PH, LP. Writing – review and editing: JR, PH.
Petr Hrabina https://orcid.org/0009-0002-3159-3737
Ludmila Pernerová https://orcid.org/0009-0004-3628-4647
Josef Suchomel https://orcid.org/0000-0002-6455-135X
Jan Robovský https://orcid.org/0000-0001-8720-9314
All of the data that support the findings of this study are available in the main text or Supplementary Information.
Goral species recognized in the 20th and 21st centuries across several basic sources, which seemed to assess gorals independently and/or using different data
Data type: xlsx
Explanation note: Taxa are arranged alphabetically by scientific names.
List of taxa and GenBank accession numbers used for the original gene analysis with 134 COI sequences
Data type: xlsx
Explanation note: Taxa are arranged alphabetically by scientific names.
Genetic Kimura two-parameter distances for COI genes among Nemorhaedus and Capricornis species
Data type: xls