Avian phenotypic convergence is subject to low genetic constraints based on genomic evidence

Background Phenotypic convergence between distinct species provides an opportunity to examine the predictability of genetic evolution. Unrelated species sharing genetic underpinnings for phenotypic convergence suggests strong genetic constraints, and thus high predictability of evolution. However, there is no clear big picture of the genomic constraints on convergent evolution. Genome-based phylogenies have confirmed many cases of phenotypic convergence in birds, making them a good system for examining genetic constraints in phenotypic convergence. In this study, we used hierarchical genomic approaches to estimate genetic constraints in three convergent avian traits: nocturnality, raptorial behavior and foot-propelled diving. Results Phylogeny-based hypothesis tests and positive selection tests were applied to compare 16 avian genomes, representing 14 orders, and identify genes with strong convergence signals. We found 43 adaptively convergent genes (ACGs) associated with the three phenotypic convergence cases and assessed genetic constraints in all three cases, from (amino acid) site mutations to genetic pathways. We found that the avian orders shared few site mutations in the ACGs that contributed to the convergent phenotypes, and that these ACGs were not enriched in any genetic pathways. In addition, different pairs of orders with convergent foot-propelled diving or raptorial behaviors shared few ACGs. We also found that closely related orders that shared foot-propelled diving behavior did not share more ACGs than did distinct orders, suggesting that convergence among these orders could not be explained by their initial genomic backgrounds. Conclusions Our analyses of three avian convergence events suggest low constraints for phenotypic convergence across multiple genetic levels, implying that genetic evolution is unpredictable at the phylogenetic level of avian order. Ours is one of first studies to apply hierarchical genomic examination to multiple avian convergent cases to assess the genetic constraints in life history trait evolution.

Four novel Picornaviruses detected in Magellanic Penguins (Spheniscus magellanicus) in Chile

Members of the Picornaviridae comprise a significant burden on the poultry industry, causing diseases such as gastroenteritis and hepatitis. However, with the advent of metagenomics, a number of picornaviruses have now been revealed in apparently healthy wild birds. In this study, we identified four novel viruses belonging to the family Picornaviridae in healthy Magellanic Penguins (Spheniscus magellanicus), a near threatened species found along the coastlines of temperate South America. We collected 107 faecal samples from 72 individual penguins. Twelve samples were initially sequenced by high throughout sequencing with metagenomics approach. All samples were subsequently screened by PCR for these new viruses, and approximately 20% of the penguins were infected with at least one of these viruses, and seven individuals were co-infected with two or more. The viruses were distantly related to members of the genera Hepatoviruses, Tremoviruses and unassigned viruses from Antarctic Penguins and Red-Crowned Cranes. Further, they had more than 60% amino acid divergence from other picornaviruses, and therefore likely constitute novel genera. That these four novel viruses were abundant among the sampled penguins, suggests Magellanic Penguins may be a reservoir for several picornaviruses belonging to different genera. Our results demonstrate the vast undersampling of wild birds for viruses, and we expect the discovery of numerous avian viruses that are related to Hepatoviruses and Tremoviruses in the future.ImportanceRecent work has demonstrated that Antarctic penguins of the genus Pygoscelis are hosts for an array of viral species. However, beyond these Antarctic penguin species, very little is known about the viral diversity or ecology in this highly charismatic avian order. Through metagenomics we identified four novel viruses belonging to the Picornaviridae family in faecal samples from Magellanic Penguins. These highly divergent viruses, each possibly representing novel genera, are related to members of the Hepatovirus, Tremovirus genera, and unassigned picornaviruses described from Antarctic Penguin and Red-crowned Cranes. By PCR these novel viruses were shown to be common in Magellanic Penguins, indicating that penguins may play a key role in their epidemiology and evolution. Overall, we encourage further sampling to reveal virus diversity, ecology, and evolution in these unique avian taxa.

Egg spottiness reflects female condition, physiological stress, and ornament expression in a common rallid species

Lay Summary • There is equivocal support for direct associations between maternal quality and deposition of protoporphyrin pigmentation (dark spots and blotches) in avian eggshells. • Research on protoporphyrin eggshell pigmentation has primarily focused on a single avian order (Passeriformes). • We examined associations of protoporphyrin-based eggshell pigmentation with female phenotypic and genetic traits in a non-passerine species, the Eurasian Coot. • Deposition of protoporphyrin in eggshells (total number per area of egg spots) positively correlated with female condition and expression of a putative bare-part ornament (frontal shield), while it was negatively associated with the level of physiological stress. • Protoporphyrin-based eggshell pigmentation acts as a reliable signal of female phenotypic (but not genetic) traits in the Eurasian Coot. • Signaling properties of protoporphyrin-based egg coloration are likely to largely differ between different evolutionary lineages of birds.

Towards reconciliation of the four world bird lists: hotspots of disagreement in taxonomy of raptors

There are currently four world bird lists referenced by different stakeholders including governments, academic journals, museums and citizen scientists. Consolidation of these lists is a conservation and research priority. In reconciling lists, care must be taken to ensure agreement in taxonomic concepts—the actual groups of individual organisms circumscribed by a given scientific epithet. Here, we compare species-level taxonomic concepts for raptors across the four lists, highlighting areas of disagreement. Of the 665 species-level raptor taxa observed at least once among the four lists, only 453 (68%) were consistent across all four lists. The Howard and Moore Checklist of the Birds of the World contains the fewest raptor species (528), whereas the International Ornithological Community World Bird List contains the most (580) and these two lists are in the most disagreement. Of the disagreements, 67% involved owls, and Indonesia was the country containing the most disagreed upon species (169). Finally, we calculated the amount of species-level agreement across lists for each avian order and found raptor orders spread throughout the rankings of agreement. Our results emphasize the need to reconcile the four world bird lists for all avian orders, highlight broad disagreements across lists and identify hotspots of disagreement for raptors, in particular.

Unexpectedly high genetic diversity in a rare and endangered seabird in the Hawaiian Archipelago

Seabirds in the order of Procellariiformes have one of the highest proportions of threatened species of any avian order. Species undergoing recovery may be predicted to have a genetic signature of a bottleneck, low genetic diversity, or higher rates of inbreeding. The Hawaiian Band-rumped Storm Petrel (‘Akē‘akē; Hydrobates castro), a long-lived philopatric seabird, suffered massive population declines resulting in its listing under the Endangered Species Act in 2016 as federally Endangered. We used high-throughput sequencing to assess patterns of genetic diversity and potential for inbreeding in remaining populations in the Hawaiian Islands. We compared a total of 24 individuals, including both historical and modern samples, collected from breeding colonies or downed individuals found on the islands of Kaua‘i, O‘ahu, Maui, and the Big Island of Hawai‘i. Genetic analyses revealed little differentiation between breeding colonies on Kaua‘i and the Big Island colonies. Although small sample sizes limit inferences regarding other island colonies, downed individuals from O‘ahu and Maui did not assign to known breeding colonies, suggesting the existence of an additional distinct breeding population. The maintenance of genetic diversity in future generations is an important consideration for conservation management. This study provides a baseline of population structure for the remaining nesting colonies that could inform potential translocations of the Endangered H. castro.

A Laurasian origin for a pantropical bird radiation is supported by genomic and fossil data (Aves: Coraciiformes)

The evolution of pantropically distributed clades has puzzled palaeo- and neontologists for decades regarding the different hypotheses about where they originated. In this study, we explored how a pantropical distribution arose in a diverse clade with a rich fossil history: the avian order Coraciiformes. This group has played a central role in the debate of the biogeographical history of Neoaves. However, the order lacked a coherent species tree to inform study of its evolutionary dynamics. Here, we present the first complete species tree of Coraciiformes, produced with 4858 ultraconserved elements, which supports two clades: (1) Old World-restricted bee-eaters, rollers and ground-rollers; and (2) New World todies and motmots, and cosmopolitan kingfishers. Our results indicated two pulses of diversification: (1) major lineages of Coraciiformes arose in Laurasia approximately 57 Ma, followed by independent dispersals into equatorial regions, possibly due to tracking tropical habitat into the lower latitudes—the Coracii (Coraciidae + Brachypteraciidae) into the Afrotropics, bee-eaters throughout the Old World tropics, and kingfishers into the Australasian tropics; and (2) diversification of genera in the tropics during the Miocene and Pliocene. Our study supports the important role of Laurasia as the geographical origin of a major pantropical lineage and provides a new framework for comparative analyses in this charismatic bird radiation.

Composition and distribution of lice (Insecta: Phthiraptera) on Colombian and Peruvian birds: New data on louse-host association in the Neotropics

The diversity of permanent ectoparasites is likely underestimated due to the difficulty of collecting samples. Lice (Insecta: Phthiraptera) are permanent ectoparasites of birds and mammals; there are approximately 5,000 species described and many more undescribed, particularly in the Neotropics. We document the louse genera collected from birds sampled in Peru (2006–2007) and Colombia (2009–2016), from 22 localities across a variety of ecosystems, ranging from lowland tropical forest and Llanos to high elevation cloud forest. We identified 35 louse genera from a total of 210 bird species belonging to 37 avian families and 13 orders. These genera belong to two suborders and three families of lice: Amblycera, families Menoponidae (present on 131 bird species) and Ricinidae (39 bird species); and Ischnocera, family Philopteridae (119 bird species). We compared our bird-louse associations with data in Price et al. (2003) and recently published Neotropical studies. The majority of bird-louse associations (51.9%) were new, with most of these coming from Passeriformes, the most diverse avian order, with the most poorly known louse fauna. Finally, we found geographical variation in louse infestation and prevalence rates. With this study, we report the first comprehensive documentation of bird-louse associations for Colombia and substantially increase the known associations documented for Peru.

A new species of the genus Amyrsidea (Phthiraptera: Amblycera: Menoponidae) parasitizing domestic chickens in Saudi Arabia

Amyrsidea Ewing, 1927 is a genus of chewing lice comprising 52 species, divided into five subgenera: Amyrsidea sensu stricto, Argimenopon Eichler, 1947, Cracimenopon Carriker, 1954, Desumenopon Carriker, 1954 and Numidimenopon Scharf & Price, 1977 (see Price et al. 2003: 86), which parasitise a wide range of hosts belonging to the avian order Galliformes (see Price et al. 2003: 321). Species of Amyrsidea can be distinguished from species of Menacanthus Neumann, 1912—the other menoponid genus with species parasitic on the same hosts—by lacking ventral spinous processes in the head (Scharf & Price 1977: 815). Revisions of all subgenera and species of Amyrsidea, including keys for their identification, were published by Scharf & Price (1977, 1983) and Scharf & Emerson (1983, 1984).

Ultraviolet-sensitive vision in long-lived birds

Long-term exposure to ultraviolet (UV) light generates substantial damage, and in mammals, visual sensitivity to UV is restricted to short-lived diurnal rodents and certain marsupials. In humans, the cornea and lens absorb all UV-A and most of the terrestrial UV-B radiation, preventing the reactive and damaging shorter wavelengths from reaching the retina. This is not the case in certain species of long-lived diurnal birds, which possess UV-sensitive (UVS) visual pigments, maximally sensitive below 400 nm. The Order Psittaciformes contains some of the longest lived bird species, and the two species examined so far have been shown to possess UVS pigments. The objective of this study was to investigate the prevalence of UVS pigments across long-lived parrots, macaws and cockatoos, and therefore assess whether they need to cope with the accumulated effects of exposure to UV-A and UV-B over a long period of time. Sequences from the SWS1 opsin gene revealed that all 14 species investigated possess a key substitution that has been shown to determine a UVS pigment. Furthermore, in vitro regeneration data, and lens transparency, corroborate the molecular findings of UV sensitivity. Our findings thus support the claim that the Psittaciformes are the only avian Order in which UVS pigments are ubiquitous, and indicate that these long-lived birds have UV sensitivity, despite the risks of photodamage.