Promiscuous pathogens: What if disease-causing fungi hybridize?

Should we be worried when two fungal pathogens are exchanging genes?

Time for something completely different. During my weekly search for papers on hybridization I came across a paper in Evolution Letters, entitled “Recent admixture between species of the fungal pathogen Histoplasma.” This spurred (not spored) my interest and I decided to dedicate a blog post to it. So, get ready for some fungi hybrids!

 

The Emergence of Virulence

First, a note on health. Studying hybridization in pathogens can help scientists understand the emergence of virulence (i.e. a pathogen’s ability to infect or damage a host). Exchanging genes through hybridization can influence virulence in two ways. First, disease-causing organisms can transfer their genes to non-pathogenic species which can consequently become virulent. Second, related species often have different strategies to infect their hosts. Hybrids can inherit both strategies, making them extra virulent. I guess the relevance of studying hybridization in pathogens is crystal clear…

Histoplasma on the microscope (from: http://www.wikipedia.com/)

 

Lung Disease

The current study focused on Histoplasma, a fungus that causes the lung disease histoplasmosis. It is one of the most common pulmatory diseases and is particularly prevalent in HIV-patients, often resulting in death. There are at least four species of Histoplasma, two in South America (H. suramericanum and H. capsulatum) and two in North America (H. ohiense and H. mississippiense). Colin Maxwell (University of North Carolina) and his colleagues focused on the North American species, which use different strategies to infect their hosts*.

 

Genetic Exchange

Previous work already indicated that these two species were exchanging genetic material. The current study confirmed these findings and explored which parts of the genome have been transferred. It turned out that intergenic sequences were over-represented in the exchanged material. These are DNA sequences that lie between functional genes. This suggests that most of the exchanged material is deleterious or lethal in the hybrids. It seems that we should not worry about the virulence of these hybrids. But the authors do provide a word of caution:

The introgressed regions in hybrid Histoplasma are enriched for those alleles that would seem least likely to affect virulence. However, gene exchange does occur, and our results do not rule out alleles that do affect virulence.

 

References

Maxwell, C.S., Sepulveda, V.E., Turissini, D.A., Goldman, W.E. & Matute, D.R. (2018) Recent admixture between species of the fungal pathogen Histoplasma. Evolution Letters 2(3), 210-220.

 

* For readers interested in the technical details: H. ohiense uses α-(1,3)-glucan in its cell wall to avoid immune recognition by the host, while H. mississippiense uses Yps3p.

It’s complicated: Hybrid hummingbirds in Mexico

Genetic study unravels the evolutionary history of an Amazilia species complex.

Hummingbirds hybridize a lot. The Avian Hybrids page of this bird order (Apodiformes) lists numerous hybrids, mostly described by Gary Graves. This high incidence of interbreeding can complicate the reconstruction of the evolutionary histories. But that doesn’t stop ornithologists from trying to figure it out. A recent study in Journal of Avian Biology describes this challenge for a Mexican species complex.

 

Mexican Mountains

Before I introduce the hummingbirds in the species complex, you need to know more about the geographical setting of this study, namely the Mexican Transition Zone (MTZ). Several avian hybrid zones have been studied in this area, which lies between the Isthmus of Tehuantepec and a belt of volcanoes running through central Mexico. This belt – known as the Trans-Mexican Volcanic Belt – cuts Mexico into northern and southern halves (see map below).

The Mexican Transition Zone, located between the Isthmus of Tehuantepec and the Trans-Mexican Volcanic Belt (in red) – adapted from http://www.wikipedia.com/

 

White-chested Hummingbirds

Now for the hummingbirds that flutter around in this Mexican Transition Zone. The white-chested hummingbird complex consists of two species, each comprising two subspecies. The violet-crowned hummingbird (Amazilia violiceps) is widely distributed from the Southern USA to Southern Mexico, and holds two subspecies: violiceps and elloiti. The green-fronted hummingbird (A. viridifrons) is endemic to Mexico and also holds two subspecies: viridifrons and villadai.

green-fronted hummingbird (A. viridifrons) – from: https://neotropical.birds.cornell.edu/Species-Account/nb/species/grfhum1/overview

 

Three Clusters

A previous study reported three clusters in this species complex: a population of violiceps north of the volcanic belt, a mixture of violiceps and viridifrons south of the volcanic belt, and a population of villadai east of the Isthmus of Tehuantepec. But how did we get to this situation? That is what Flor Rodríguez-Gómez and Juan Francisco Ornelas attempted to figure out using 10 microsatellites.

Violet-crowned hummingbird (Amazilia violiceps) – from: https://www.audubon.org/field-guide/bird/violet-crowned-hummingbird

 

Comparing Scenarios

The genetic analyses confirmed the results from the previous study and indicated a complicated history of ancient gene flow. The researchers compared several scenarios of divergence and gene flow. Here is the most likely scenario: first, there was a split that gave rise to the violet-crowned hummingbird (A. violiceps) and the green-fronted hummingbird (A. viridifrons). This split was probably driven by the Isthmus of Tehuantepec. Later, the green-fronted hummingbird split into the two subspecies viridifrons and villadai.

And now it gets a bit uncertain. The mixed population of viridifrons and violiceps can be the result of violiceps expanding its range and establishing a contact zone with viridifrons. Alternatively, viridifrons is a hybrid population between violiceps and villadai (if this sounds confusing, check the figure below). Either way, hybridization has been a key process in the evolutionary history of this species complex.

The distribution of the hummingbird populations in Mexico and two possible scenarios. Colors represent different subspecies: violiceps (purple), viridifrons (orange) and villadai (yellow). Adapted from Rodríguez-Gómez & Ornelas (2018) Journal of Avian Biology.

 

References

Rodríguez-Gómez, F. & Ornelas, J.F. (2018) Genetic structuring and secondary contact in the white-chested Amazilia hummingbird species complex. Journal of Avian Biology 49(4), jav-01536.

 

The paper has been added to the Apodiformes page.

Knock, Knock! Who is there? Woodpeckers, but how many species?

Two recent genetic studies attempt to distinguish between woodpeckers species.

The majority of bird species have been described based on morphological or vocal differences. The application of molecular data has put these taxonomic decisions to the test: in some cases new cryptic species popped up, while in other cases morphologically distinct birds turned out to be genetically indistinguishable (redpolls and wagtail subspecies are nice examples of the latter situation). Two recent studies on woodpeckers illustrate this ornithological struggle between morphology and genetics.

 

A Flicker of Hope

Let’s start in North America. Here, you can find one of the best studied avian hybrid zones, namely the one between red-shafted flicker (Colaptes auratus cafer) and yellow-shafted flicker (C. a. auratus). The species complex to which these woodpeckers belong also includes the gilded flicker (C. chrysoides). Previous studies, using traditional molecular markers – such as allozymes – could not discriminate between these three taxa. Even a recent genomic analysis was unable to tell them apart.

Nevertheless, Stepfanie Aguillon and her colleagues decided to give it another go. They sampled birds far from the hybrid zone and used a dataset of thousands of SNP loci to see if they could distinguish among the three taxa. And despite low levels of genetic divergence, they were able to “clearly and conclusively distinguish the three taxa genetically for the first time.”

From left to right: yellow-shafted, red-shafted and gilded flicker.

 

Confusion in Celeus

Moving on to South America, where two woodpecker species have ornithologists scratching their heads. The taxonomy of scaly-breasted woodpecker (Celeus grammicus) and waved woodpecker (C. undatus) has been a topic of debate: are we dealing with one or two species here? Larissa Sampaio and her colleagues addressed this question by sequencing the DNA (3 mitochondrial and 3 nuclear markers) and comparing the plumage of these birds.

The genetic nor the morphological analyses could distinguish between the proposed species. These results suggest a very recent and possibly incomplete separation – estimated at about 50,000 years ago – of these lineages. The authors conclude that scaly-breasted woodpecker and waved woodpecker and best treated as a single species.

Waved woodpecker and scaly-breased woodpecker are probably one and the same species.

 

Patterns vs. Processes

But what if the researchers had used genomic data to study these South American woodpeckers, similar to the study on flickers? Would they have succeeded in discriminating between the species? Is more genomic data always better? In my opinion, these are not the right questions to ask. The goal is not to genetically discriminate between taxa that look alike, but rather to better understand the processes behind the genetic patterns. It is difficult to discriminate between these woodpeckers (in both the North and South American examples). Why is this? Are we dealing with a recent split? Or is gene flow preventing genetic divergence? Maybe there are a few genomic regions that determine the differences in plumage? These woodpeckers provide the ideal systems to study such questions. I am sure you will read about them soon at Avian Hybrids!

 

References

Aguillon, S.M., Campagna, L., Harrison, R.G. & Lovette, I.J. (2018) A flicker of hope: Genomic data distinguish Northern Flicker taxa despite low levels of divergence. The Auk 135, 748-766.

Sampaio, L., Aleixo, A., Schneider, H., Sampaio, I., Araripe, J. & Sena de Rêgo, P. (2018) Molecular and plumage analyses indicate incomplete separation of two woodpeckers (Aves, Picidae). Zoologica Scripta 47, 418-427.

 

These papers have been added to the Piciformes page.

 

Glacial cycles culminate in hybridization events between North American Stoat populations

Genomic study pinpoints hybridization events in the Stoat.

The waxing and waning of the ice sheets during the Pleistocene had a major impact on the genetic make-up of current populations. When the ice expanded, populations were separated in distinct ice-free areas (called refugia) where they diverged from one another. Later, when the ice retreated, the populations colonized the newly available land and sometimes came into secondary contact with their long-lost relatives from other refugia. Recently, I described how this process sculpted the evolutionary history of Coal Tits (Periparus ater) in Europe. But similar scenarios unfolded in North America.

 

Four Refugia

A study in the journal Communications Biology explored the impact of the Pleistocene glacial cycles on the genetic structure of Stoat* (Mustela erminea) populations. Previous work – based on mitochondrial DNA – documented four distinct lineages of Stoat. Interestingly, these four lineages correspond to four refugia: Beringia, North Pacific Coast, East and West. I have highlighted these locations in red circles on the map below (based on a paper by Nathan Swenson and Daniel Howard).

As you can see from the arrows on the map, multiple contact zones are possible when populations expand from their refugia. In the case of the Stoat, two contact zones – the green areas – are relevant: one is located near the North Pacific Coast refugium, while the other is close to the Beringia refugium. The authors refer to the latter as the Alaska-Yukon contact zone. (Quick note: my map is quite crude. For a more detailed overview, check the original publication).

The four glacial refugia (red circles) that correspond to the mitochondrial lineages of Stoat. The green areas indicate two contact zones. (Adapted from Swenson & Howard 2005)

 

 

Two Hybridization Events

To figure out what happened at these contact zones, Jocelyn Colella (University of New Mexico) and her colleagues sequenced the whole genome of ten Stoats. The comparison of these genomes revealed two hybridization events: one recent event along the border between Alaska and Yukon, and a more ancient event (about 394,000 years ago) along the North Pacific Coast.

This study nicely shows how the Pleistocene glacial cycles can result in a kind of merge-and-diverge dynamics in which populations diverge in isolated refugia only to (partly) merge again in contact zones. With every cycle, the divergence slightly increases until hybridization at the contact zones ceases; the populations have become genetically too different to interbreed and can be considered distinct species. Whether this will also happen – or has already happened – in the Stoat remains to be tested.

A Stoat (Mustela erminea)

 

References

Colella, J.P., Lan, T., Schuster, S.C., Talbot, S.L., Cook, J.A. & Lindqvist, C. (2018) Whole-genome analysis of Mustela erminea finds that pulsed hybridization impacts evolution at high latitudes. Communication Biology 1:51.

 

* The Stoat is also known as Ermine or Short-tailed Weasel, but for consistency I will stick with Stoat here.

 

Why are seabird hybrids so rare?

Study reports hybrids between White-capped and Black-browed Albatross.

Hybridization in seabirds is rare. However, occasionally hybrids are reported, see for instance this recent case of giant petrels (genus Macronectes). In the ornithological journal Ibis, Richard Phillips, John Cooper and Theresa Burg report a similar case of hybridization in albatrosses (genus Thalassarche).

 

Three Chicks

In 2003 a male White-capped Albatross (T. steadi) was observed in a colony of Black-browed Albatrosses (T. melanophris) at Bird Island, South Georgia. This male paired with a female Black-browed Albatross, rearing three chicks (between 2008 and 2010). The researchers collected blood samples and sequenced the DNA of these putative hybrids. The genetic analyses revealed that two chicks were hybrids, whereas the third one was a pure Black-browed Albatross. The last chick was probably the result of extra-pair copulation, in which the female mated with another male (a behavior that is quite common in these species).

A White-capped Albatross (from: http://nzbirdsonline.org.nz/)

 

Isolation Mechanisms

So, we can add another hybrid combination to our list of seabird hybrids. Although several hybrids have been reported, hybridization is still relatively rare in seabirds compared to terrestrial birds. Why is this? The authors propose several explanations.

First, exploratory behavior might influence the incidence of hybridization. Seabirds are very philopatric, they generally return to their place of birth for breeding. Breeding site vagrancy is quite rare and usually involves single individuals that explore new territories. The loyalty to their breeding grounds reduces the opportunities for hybridization.

But what about all these mixed colonies? Why are mixed pairings so rare despite the fact that some species breed side by side? There might be some morphological or behavioral differences that prevent the formation of mixed pairings. For example, variation in coloration of certain body parts can function as an isolation mechanism. Think of the distinctly colored feet of booby species (genus Sula). Alternatively, the species might breed at different times of the year (allochrony).

Clearly, there are several barriers to cross before the production of a hybrid chick. But it does happen, indicating that ‘life finds a way.’

A pair of Black-browed Albatrosses with a chick (from: http://ava7.com/)

 

References

Phillips, R.A., Cooper, J. & Burg, T.M. (2018) Breeding-site vagrancy and hybridization in albatrosses. Ibis

 

The paper has been added to the Procellariiformes page.

 

Probing the Puzzling Plumage Patterns of White Wagtails

How can we explain plumage patterns in white wagtails subspecies?

Wagtail taxonomy is a mess. Numerous subspecies have been described based on morphological differences, but they are not supported by genetic data. A recent study in Journal of Evolutionary Biology took another look at several subspecies of the White Wagtail (Motacilla alba). Could they explain the mismatch between plumage and genetics?

 

Six Subspecies

Georgy Semenov and his colleagues sampled six of the nine recognized subspecies – alba, personata, baicalensis, ocularis, lugens and leucopsis – and sequenced 17 microsatellites. In line with previous studies, the genetic analyses revealed little population structure and weak divergence among the subspecies.

Distribution of White Wagtail (Motacilla alba) subspecies (from http://www.wikiwand.com/en/White_wagtail)

 

Puzzling Plumage Patterns

How can ornithologists explain this peculiar pattern of clear morphological differences without genetic differentiation? Recent genomic studies have shown that a small fraction of the genome can underlie such plumage variation (see for example crows and warblers). Something similar might explain the plumage patterns in White Wagtail subspecies.

A white wagtail by the water (from: http://www.hbw.com/)

 

The authors of the current study speculate that a small toolkit of genes might have been shuffled around by hybridization, resulting in the different wagtail head patterns. These patterns are confined to a small number of patches – throat, back and sides of the head and neck – which can be either black or grey. Think shuffling a deck of cards and randomly extracting a combination of cards: black throat, grey back, black on the sides. Hey, that combination looks like personata! (Try it yourself, pick three random colors for each patch and see which subspecies you end up with)

This idea is actually supported by some keen observations. For example, the subspecies persica (from Iran) resembles a certain hybrid between alba and personata (read more about these hybrids here). Similarly, the Moroccan subspecies subpersonata looks like a alba x personata hybrid with the eye-stripe of a lugens x ocularis pair. Suddenly, this is starting to make more sense…

The subspecies persica looks surprisingly similar to a hybrid between personata and alba (from: http://commons.wikimedia.com/)

 

References

Semenov, G.A., Koblik, E.A., Red’Kin, Y.A. & Badyeav, A.V. (2018) Extensive phenotypic diversification coexists with little genetic divergence and lack of population structure in the White Wagtail subspecies complex (Motacilla alba). Journal of Evolutionary Biology

 

The paper has been added to the Motacillidae page.

Glorious Bustards: How many species of great bustard are there?

Genetic study argues to raise the status of great bustard subspecies to the species level.

It could be a typical question in a pub quiz: ‘What is the heaviest bird capable of flight?’ The answer is the great bustard (Otis tarda), which can reach weights of nearly 20 kilograms. Currently, ornithologists recognize two subspecies of this flying heavyweight: the Eastern (dybowskii) and the Western (tarda) great bustard. But this taxonomic arrangement might change…

 

East and West

The Eastern subspecies is restricted to Siberia, Mongolia and China where about 1,500 individuals live. The Western subspecies is more numerous – between 42,000 and 55,000 individuals – and ranges from Portugal to Xinjang (western China). Aimee Elizabeth Kessler and her colleagues collected samples across this distribution and sequenced two mitochondrial genes.

The genetic analyses showed a clear separation between both subspecies that probably diverged about 1.4 million years ago. Gene flow was estimated at less than one individual per generation. Interestingly, there was one ‘misplaced’ sequence from Xinjang, which suggests that there might be a hybrid zone at this location. Definitely something to explore further.

The Great Bustard – one or two species? (from: http://www.wikipedia.com/)

 

Plumage Differences

The genetic differentiation and low levels of gene flow are consistent with the proposal of considering dybowskii and tarda as distinct species. But genetic data alone are not sufficient to support this decision: ecological, behavioral and morphological studies are needed to make a convincing case. In 1874, Taczanowksi already described dybowskii as a separate species based on morphometric and plumage differences.

Indeed, there are some differences between the subspecies in the extent of white plumage on the wings and tail. And the plumes around the bill are differently placed in both subspecies. Perhaps this plumage variation allows females to discriminate between (sub)species during the elaborate displays of the males (see video below). That would push these bustards one step closer to the glorious status of species.

 

 

References

Kessler, A.E., Santos, M.A., Flatz, R., Batbayar, N., Natsagdorj, T., Batsuuri, D., Bidashko, F.G., Galbadrakh, N., Goroshko, O., Khrokov, V.V., Unenbat, T., Vagner, I.I, Wang, M. & Smith, C.I. (2018) Mitochondrial Divergence between Western and Eastern Great Bustards: Implications for Conservation and Species Status. Journal of Heredity.

Mind the gaps: The incompleteness of complete avian genome assemblies

“You complete me.”

– Tom Cruise in Jerry Maguire (1996)

On this blog, I regularly write about studies using whole genome data, see for example the hybrid genome of the Italian Sparrow or the search for migration genes in the Willow Warbler genome. Indeed, ornithology is entering the genomics era. But did you ever wondered about the ‘wholeness’ of these whole genomes?

 

Genome Assemblies

In a recent paper in Molecular Ecology Resources, Valentina Peona, Matthias Weissensteiner and Alexander Suh explore the completeness of current avian genome assemblies. At the moment, there are more than 100 bird genomes available at Genbank and the Bird 10,000 Genomes Project (B10K) – which aims to sequence all extant bird species – has generated over 300 assemblies. That is a lot of data.

But how complete are these assemblies? To figure this out, the authors compared summary statistics of the genome assemblies with estimates of genome size based on flow cytometry. This analysis revealed that between 7 and 42 percent of bird genomes was missing.

The B10K Project aims to sequence the genomes of all living bird species (from: https://b10k.genomics.cn/)

 

Mind the Gaps

Where is all this missing data? Unlike your car keys, the location of this missing data can easily be deduced. Most genome assemblies are based on short read technologies, which sequence about 100 base pairs at a time. Next, these short reads need to be combined into contiguous sequences (‘contigs’) and linked contigs (‘scaffolds’). If the whole genome is the distance between Rome and Paris, then 150 bp would be the size of a smartphone (see figure below). That is a lot of smartphones you have to line up…

A nice representation of the differences in scale of several sequencing techniques (from Peona et al. 2018 Molecular Ecology Resources).

Scaffolds consist of contigs and assembly gaps (placeholders of undetermined ‘N’ nucleotides). This is where you can find the missing data. These assembly gaps mostly contain repetitive elements such as interspersed repeats (transposable elements and endogenous viruses) and tandem repeats (microsatellites and satellites). These sequences are difficult to assemble because of their repetitive nature: “Like a puzzle piece occurring multiple times in a single puzzle game.”

 

Long Reads Technologies

So, how can we deal with these gaps? New techniques that sequence long stretches of DNA (millions of base pairs) might provide the solution. Think of 10X Genomics Linked-Read sequencing, BioNano optical mapping and chromosome conformation capture (Hi-C). This is nicely illustrated by the recent developments in sequencing the Chicken genome: comparing the short-read genome (galGal4) with a more recent long-read genome revealed that the amount of missing data decreased from 14.1 to 2.4 percent. We are not there yet, but we are getting there.

Two chicks exploring a map of their genome (from: http://www.wikipedia.com/)

References,

Peona, V., Weissensteiner, M.H. & Suh, A. (2018) How complete are ‘complete’ genome assemblies? – An avian perspective. Molecular Ecology Resources. doi: 10.1111/1755-0998.12933

The Flight of the Condor: How the Andes shapes patterns of gene flow

Study shows how the topography of the Andes influences genetic patterns of Andean condor populations.

Where would you fly to if you were an Andean condor (Vultur gryphus)? These majestic birds can travel up to 350 kilometers per day. Given their dispersal capacity, you would expect that their genetic population structure is panmictic. This means that each individual can interbreed with any other individual in the population, without restrictions. But is this really the case? A recent study in the journal Diversity and Distributions put this expectation to the test.

A soaring Andean condor (from: http://www.nationalgeographic.com.au/andean-condor/)

 

South American Ecoregions

Julian Padró and his colleagues sequenced 278 individual birds from four different regions in Argentina: Puna, Chaco, Monte and Patagonia. For those of you unfamiliar with ecological regions in South America, here is a quick overview and map:

• Puna: montane grasslands and shrublands biome in the central Andes
• Chaco: hot and semi-arid lowland in Argentina, Bolivia and Paraguay
• Monte: region of dry thorn scrub and grasslands in Argentina
• Patagonia: southern section of the Andes in Argentina and Chile

Sampling locations across the range of Andean condors in Argentina (from Padró et al. 2018)

 

Mountain Hopping

The genetic analyses – based on 13 microsatellites – indicated the existence of two subpopulations: one in the north (Puna and Chaco) and one in the south (Patagonia) with a contact zone in the middle (Monte). So, despite their impressive dispersal capacity, there is some population structure.

Interestingly, genetic divergence is higher between Patagonia and Chaco compared to Patagonia and Puna, although the former locations are geographically closer. What is going on here? Given that condors try to optimize their energy expenditure during flight, the researchers think that mountains might provide a clue:

The Puna and Patagonia are connected by the Andes mountain range, which create strong updrafts and a “high-lift” efficient environment for large soaring birds, like condors, to move. In contrast, thermal updrafts in areas with little topographic relief, as the plains surrounding the central mountains of Chaco, are weaker and prone to disruption by wind speed.

In a sense, the ‘archipelago’ of mountains provides a series of stepping stones between Puna and Patagonia. This observation nicely shows how topographic features can influence genetic patterns.

 

An Andean condor in Patagonia (from: http://www.conservacionpatagonica.org/)

 

Endangered

From a conservation point of view, this mountainous corridor needs to protected. Along with 15 (out of 22) other vulture species, the Andean condor is threatened. These birds are listed as “Near Threatened” by the IUCN and numbers are still declining. Surprisingly, this endangered status is not reflected in their genes. The present study found no evidence for reduced genetic diversity or recent bottlenecks. However, the effects of population decline might take some time to become apparent. Hence, there is no reason to lay back and relax. We wouldn’t want to lose such an amazing bird.

 

References

Padró, J., Lamertucci, S.A., Perrig, P.L. & Pauli, J.N. (2018) Evidence of genetic structure in a wide-ranging and highly mobile soaring scavenger, the Andean condor. Diversity and Distributions.

Readers’ Hybrids: A lot of hybrid parrots!

A nice collection of hybrids between several parrot species.

This week reader Nico Rosseel send me a big collection of hybrid parrot pictures. All photographs show captive birds, and this is not that surprising. My Ibis paper on hybridization in birds – the paper that actually started this blog in 2015 – showed that captive hybrids are fairly common in the parrot order Psittaciformes.

The incidence of hybridization in birds. The size of the pie charts is proportional to the number of species in the respective Order. Colors indicate no hybridization (green), hybridization in nature (blue) and hybridization in captivity (red). The black arrow highlights the Psittaciformes. (adapted from Ottenburghs et al. 2015 Ibis)

But let’s have a look at Nico’s pictures. I have added photos of the parental species, so you can easily compare them to the hybrids.

Blue-and-yellow macaw x red-and-green macaw

The parental species: Blue-and-yellow macaw (Ara ararauna) and red-and-green macaw (A. chloptera)

And the hybrid.

 

Blue-and-yellow macaw x military macaw

The parental species: Blue-and-yellow macaw (Ara ararauna) and military macaw (A. militaris)

And the hybrid.

 

Goffin’s cockatoo x citron-crested cockatoo

The parental species: Goffin’s cockatoo (Cacatua goffiana) and citron-crested cockatoo (C. sulphurea citrinocristata)

And the hybrid.

 

Cardinal lory x yellowish-streaked lory

The parental species: Cardinal lory (Pseudeos cardinalis) and yellowish-streaked lory (Chalcopsitta scintillata)

And the hybrid.

 

Red lory x rainbow lorikeet

The parental species: red lory (Eos rubra) and rainbow lorikeet (Trichoglossus haematodus)

And the hybrid

 

Meyer’s parrot x  red-bellied parrot

The parental species: Meyer’s parrot (Poicephalus meyeri) x  red-bellied parrot (P. rufiventris)

And the hybrid.

 

Many thanks to Nico for sharing these pictures. Feel free to contact me and send in your own hybrid observations. More information on hybridization in parrots can be found on the Psittaciformes page.