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Hydrobates (1 Viewer)

Peter Kovalik

Well-known member
Slovakia
Taylor, R. S., Bailie, A., Gulavita, P., Birt, T., Aarvak, T., Anker-Nilssen, T., Barton, D. C., Lindquist, K., Bedolla-Guzmán, Y., Quillfeldt, P. and Friesen, V. L. (2017), Sympatric population divergence within a highly pelagic seabird species complex (Hydrobates spp.). J Avian Biol. Accepted Author Manuscript. doi:10.1111/jav.01515n

Abstract:

Both physical and non-physical barriers can restrict gene flow among seabird populations. Understanding the relative importance of non-physical barriers, such as breeding phenology, is key to understanding seabird biodiversity. We investigated drivers of diversification in the Leach’s storm-petrel species complex (Hydrobates spp.) by examining population genetic structure across its range. Variation in the mitochondrial control region and six microsatellite loci was assayed in birds sampled from breeding colonies throughout the North Atlantic and North Pacific (H. leucorhoa leucorhoa), as well as from San Benito Islands (H. l. chapmani), and two seasonal populations in Guadalupe (summer breeding H. socorroensis and winter breeding H. cheimomnestes), Mexico. Weak but significant differentiation was found between populations of H. l. leucorhoa breeding in the Atlantic versus North Pacific, as well as between H. l. chapmani and H. l. leucorhoa, and between H. socorroensis and H. cheimomnestes within Guadalupe. In contrast, strong differentiation in both mitochondrial DNA and microsatellites was found between H. leucorhoa and both H. socorroensis and H. cheimomnestes. Phylogenetic reconstruction suggested the Guadalupe seasonal breeding populations are sister taxa, at least in their mitochondrial DNA. Non-physical barriers to gene flow appear to be more important than physical barriers in driving divergence within the Leach’s storm-petrel species complex. In particular, allochronic speciation may have occurred between the seasonal populations within Guadalupe. Further work should include higher resolution sequencing to confirm results, and an increased sampling effort, particularly within the California area, to fully resolve the relationship between H. l. leucorhoa and H. l. chapmani.
 
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BirdLife's Globally Threatened Bird Forums

Leach’s Storm-petrel (Hydrobates leucorhous) is being split: assessment of newly recognised taxa.
Posted on May 11, 2018 by James Westrip (BirdLife)

Following a taxonomic reassessment, Leach’s Storm-petrel (Hydrobates leucorhous) has been split on the HBW/BirdLife International checklist into H. leucorhous, H. socorroensis and H. cheimomnestes. When treated as subspecies, H. l. socorroensis was referred to as Townsend’s Storm-petrel, and H. l. cheimomnestes was referred to as Ainley’s Storm-petrel (Carboneras et al. 2018), but the use of these common names for the newly recognised species is still to be confirmed.

The newly recognised H. socorroensis and H. cheimomnestes both are only known to breed on islets by Guadalupe Island, Mexico, with potentially a combined population of only 5,000 pairs (Brooke 2004). H. socorroensis breeds on the islets of Islote Negro and Islote Afuera from May/June to October/November, while H. cheimomnestes breeds at the opposite time of the year (November/December to April/May) on the same islets as well as also on Gargoyle Rock (Howell 2012). H. socorroensis may also breed on the mainland of Guadalupe, but feral cats have had a major impact on storm-petrels on the island (e.g. Guadalupe Storm-petrel, Hydrobates macrodactylus [see BirdLife International 2018b]), and its persistence there is uncertain (Howell 2012).

The pre-split species was widespread across the North Atlantic and North Pacific (and a limited number of breeding records from the southern hemisphere) (see Carboneras et al. 2018), with an overall population size estimate of 6.7 to 8.3 million breeding pairs. Therefore, the removal of the two newly recognised species from an assessment of the newly defined H. leucorhous will have a negligible impact on the species’s status. Therefore, it is proposed that the newly defined H. leucorhous continue to be listed as Vulnerable under criteria A2bce+3bce+4bce as per the pre-split species (see BirdLife International 2018a).

As mentioned above, the major threat to species on Guadalupe comes from invasives. Feral cats will prey upon individuals, and goats may compound this threat by trampling breeding burrows. It is not certain whether such invasives have made it to the offshore islets though, and so their direct impact on populations there are uncertain. The Guadalupe Murrelet (Synthliboramphus hypoleucus), which has a slightly larger breeding range than both of these storm-petrels (see BirdLife International 2018c), is also thought to be threatened by drowning in gill-nets, disturbance, light pollution and organochloride pollution (Drost and Lewis 1995), though these have not been identified as important threats to the pre-split H. leucorhous. Therefore, it is not certain whether these threats are having any impact at all on the newly recognised taxa in this region. However, because of their highly restricted ranges and the key threat from invasives, both species could warrant listing as threatened. Thus, both H. socorroensis and H. cheimomnestes have been assessed here against all criteria.
 
BirdLife's Globally Threatened Bird Forums

Band-rumped Storm-petrel (Hydrobates castro) is being split: assessment of newly recognised taxa.
Posted on May 11, 2018 by James Westrip (BirdLife)

Following a taxonomic reassessment, the Band-rumped Storm-petrel, Hydrobates castro, has been split on the HBW/BirdLife International checklist into H. castro and H. jabejabe.

H. castro encompasses the vast majority of the range of the pre-split species and with no evidence to contradict its current listing, it is proposed that this newly recognised taxa be listed as Least Concern. H. jabejabe, on the other hand, has a far more restricted range, only being known to breed in the Cape Verde Islands. Hazevoet (1994) lists the species as breeding on 10 islands, although this has only been confirmed for half of these islands, and Oliveira et al. (2013) provide evidence of possible breeding on Santa Luzia too.

Seabirds in the Cape Verde Islands face a range of threats, of which one of the key ones has been identified to be human exploitation of the breeding colonies (Hazevoet 1994). However, Hazevoet (1994) does stress that this is predominantly directed towards larger species and may not directly affect smaller petrel species. However, for these species a bigger impact may come indirectly because of this threat, with the trampling and collapse of breeding burrows as people try to collect the other, larger species, as well as carrying out other collecting activities (e.g. for shellfish) (Hazevoet 1994). Invasive alien species also impact on seabird colonies, with cats and rats, and potentially mice, posing a predation threat; while goats have had a significant impact on some seabird colonies by trampling breeding burrows (Hazevoet 1994). Pollution and the impact of fisheries were not thought to be having a significant impact in Cape Verde waters in the 1990s (Hazevoet 1994), although the current impact of these potential threats now is not known.
 
Flood RL, Lima RF, Melo M, Verbelen P, Wagstaff WH. 2019. What is known about the enigmatic Gulf of Guinea band-rumped storm petrels Hydrobates cf. castro? Bull. Brit. Ornithol. Cl., 139: 173-186.

Summary.—We present what is known about the Gulf of Guinea band-rumped storm petrels Hydrobates cf. castro to identify priority areas for research and conservation. Addressed are: occurrence in the Gulf of Guinea, including museum specimens, at-sea records, observations on the islands, and potential breeding sites; seasonality, the timing of breeding inferred from condition of trapped birds and birds at sea in primary moult; morphology, including biometrics, structure, plumage aspect; aerial vocalisations at the suspected breeding grounds; and taxonomy. The first photographs and sonograms pertaining to this population to be published are also presented. The evidence indicates that this storm petrel is present in the Gulf of Guinea year-round. It almost certainly breeds on São Tomé during both the wet and long dry seasons, and breeding is probably protracted, possibly seasonal. Morphology indicates a degree of distinctiveness and aerial vocalisations suggest possible taxonomic affinities with Cape Verde Storm Petrel H. jabejabe. Our observations are provisional and further research is required. The three most pressing matters for future research are clarifying taxonomy, locating breeding colonies and identifying key threats.

Paper: https://doi.org/10.25226/bboc.v139i2.2019.a10
Full issue: https://doi.org/10.25226/bboc.v139i2.2019.a12
 
IOC still maintain Oceanodroma as a separate genus - any reasons for their reluctance to merge it into Hydrobates?
For some possible reasons, you can read the comments to the SACC proposal referenced by Peter above. (Currently pending, but all votes so far are negative.)

(The issue with the markhami sample in the Wallace et al study, brought forward by Alvaro there, certainly seems real. It does not follow that "no genetic information exists for markhami", however -- 6 ND1 sequences were produced by Sausner et al 2016 (see their Fig. 10; the sequences are [in GenBank]).)
 
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For some possible reasons, you can read the comments to the SACC proposal referenced by Peter above. (Currently pending, but all votes so far are negative.)
Thanks!

The comment therein
genetic support is strong for recognition of four clades as genera, all of which are predicted to be evolving separately since the Miocene age, i.e. older than most groups we label as genera
is perhaps of low significance, as storm petrels are such long-lived birds (generation times 10-30 years), their evolution is much slower than short-lived birds like passerines.
 
Rebecca S. Taylor, Mark Bolton, Annalea Beard, Tim Birt, Petra Deane-Coe, André F. Raine, Jacob González-Solís, Stephen C. Lougheed, Vicki L. Friesen. Cryptic species and independent origins of allochronic populations within a seabird species complex (Hydrobates spp.). Molecular Phylogenetics and Evolution, In Press, Accepted Manuscript, Available online 3 July 2019.

Abstract:

Humans are inherently biased towards naming species based on morphological differences, which can lead to reproductively isolated species being mistakenly classified as one if they are morphologically similar. Recognising cryptic diversity is needed to understand drivers of speciation fully, and for accurate estimates of global biodiversity and assessments for conservation. We investigated cryptic species across the range of band-rumped storm-petrels (Hydrobates spp.): highly pelagic, nocturnal seabirds that breed on tropical and sub-tropical islands in the Atlantic and Pacific Oceans. In many breeding colonies, band-rumped storm-petrels have sympatric but temporally isolated (allochronic) populations; we sampled all breeding locations and allochronic populations. Using mitochondrial control region sequences from 754 birds, cytochrome b sequences from 69 birds, and reduced representation sequencing of the nuclear genomes of 133 birds, we uncovered high levels of genetic structuring. Population genomic analyses revealed up to seven unique clusters, and phylogenomic reconstruction showed that these represent seven monophyletic groups. We uncovered up to six independent breeding season switches across the phylogeny, spanning the continuum from genetically undifferentiated temporal populations to full allochronic species. Thus, band-rumped storm-petrels encompass multiple cryptic species, with non-geographic barriers potentially comprising strong barriers to gene flow.
 
Rebecca S. Taylor, Mark Bolton, Annalea Beard, Tim Birt, Petra Deane-Coe, André F. Raine, Jacob González-Solís, Stephen C. Lougheed, Vicki L. Friesen. Cryptic species and independent origins of allochronic populations within a seabird species complex (Hydrobates spp.). Molecular Phylogenetics and Evolution, In Press, Accepted Manuscript, Available online 3 July 2019.

Interestingly the above link to the abstract includes an image with the authors' tree:
https://ars.els-cdn.com/content/image/1-s2.0-S105579031930123X-ga1_lrg.jpg

Their results / reconstruction suggest these 7 clades:
Cape Verde
Azores hot season breeders
all other N Atlantic populations
all S Atlantic populations
Galapagos
Hawaii
Japan

I assume that the mystery band-rumped type birds seen in the area of northern Melanesia (Solomon Islands) / S Micronesia were not sampled. I would guess there are no specimens from this region?
 
Their results / reconstruction suggest these 7 clades:
Cape Verde
Azores hot season breeders
all other N Atlantic populations
all S Atlantic populations
Galapagos
Hawaii
Japan
Except the Azores hot season birds are a paraphyletic grade, not a clade?


Where does Leach's fit in this diagram?
 
Their results / reconstruction suggest these 7 clades:
Cape Verde
Azores hot season breeders
all other N Atlantic populations
all S Atlantic populations
Galapagos
Hawaii
Japan

The seven clades seem to correspond to the available names:

Cape Verde = jabejabe (Bocage, 1875)
Azores hot season breeders = monteiroi (Bolton et al., 2008)
all other N Atlantic populations = castro (Harcourt, 1851) - incl. "granti"?
all S Atlantic populations = helena (Mathews, 1934)
Galapagos = bangsi (Nichols, 1914)
Hawaii = cryptoleucura (Ridgway, 1882)
Japan = kumagai (Mathews, 1938)

love it when that happens
 
That SACC proposal figure is Fig. 3 in Wallace et al 2017, http://dx.doi.org/10.1016/j.ympev.2016.09.025 -- for free access, see [here]. The Leach's group will also include Markham's based on sequences from Sausner et al 2016 (see #7 above). Beware that the support of the node grouping this clade with the band-rumped clade is poor, however.
Except the Azores hot season birds are a paraphyletic grade, not a clade?
I'm not clear why they used this particular reconstruction for the graphical abstract, as indeed the 7 groups are not reciprocally monophyletic there, thus the tree seems to run against the paper's conclusions... (But note that the nodes which contradict group monophyly in this tree are not strongly supported; and the geometry of the tree [much shorter branches leading to all the samples in the "Azores hot" grade than in the main "non-Cape Verde" group -- as if evolution had suddenly 'fastened' in this main group, while it remained 'slower' in "Azores hot" birds] is also a bit "unexpected": this should make us doubly wary about nodes that are not fully supported.)

The tree in the abstract was constructed from SNP data. The groups are reciprocally monophyletic in the tree based on mitochondrial data: https://ars.els-cdn.com/content/image/1-s2.0-S105579031930123X-gr5.jpg.

There is some admixture, though, as shown by the control region network here: https://ars.els-cdn.com/content/image/1-s2.0-S105579031930123X-gr4.jpg . In particular, quite a few "North Atlantic" birds appear to have "Cape Verde"-type haplotypes. (There is also a complete mt-genome in GenBank of a bird said to be from the Azores -- from [this paper], [sequence here] -- which is strikingly jabejabe-like; so I had already been wondering about this, actually.)
castro (Harcourt, 1851) - incl. "granti"?
Yep. "Our analysis provides no support for genetic or taxonomic separation among other North Atlantic cool season and hot season populations (the former often referred to as ‘Grant’s storm-petrel’)."
 
It also occurs to me that there is another unresolved (and perhaps unsampled as yet) possible taxon on and around St Helena as there are believed to be hot and cold season breeders there as well. I believe it is little investigated but know Bob Flood is keen on the subject as he was the one from whom I heard about it. It will be curious to see more details of the St Helena and Ascención specimens.
 
It also occurs to me that there is another unresolved (and perhaps unsampled as yet) possible taxon on and around St Helena as there are believed to be hot and cold season breeders there as well. I believe it is little investigated but know Bob Flood is keen on the subject as he was the one from whom I heard about it. It will be curious to see more details of the St Helena and Ascención specimens.
The "South Atlantic Ocean" samples here are said to include 23 "cool season" and 28 "hot season" breeders from Ascension, and 18 "cool season" and 35 "hot season" breeders from St Helena for mitochondrial data; and 13 "cool season" and 10 "hot season" breeders from Ascension, and 11 "cool season" and 12 "hot season" breeders from St Helena for SNP data.
 

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