The Beak of the Bullfinch: Remains of an Extinct Bird Species Found on the Azores

There used to be more than one Azores Bullfinch.

The Azores Bullfinch (Pyrrhula murina) is one of the rarest songbirds on this planet. And I have seen it! In 2011, I travelled to the Azores, a Portugese archipelago in the middle of the Atlantic Ocean, to collect snails for my Master thesis. But I was on a secret mission, I wanted to see the Azores Bullfinch, also known as Priolo. This small passerine only occurs on the island of Sao Miguel, where it is restricted to a small patch of native laurasilva forest. In 2008, the population was estimated at about 800 individuals. During one of the expeditions into the forest, I noticed a bird hopping around in the bushes. It turned out to be a Priolo! Here is one of the pictures I was able to make.




A recent study, published in the scientific journal Zootaxa, reveals that there used to be another species of finch on the Azores. Researchers found bones in a small cave on the island of Graciosa. The bones showed that the extinct species – named Pyrrhula crassa – was larger than its living relatives. The evolutionary history of this second Azores bullfinch remains a mystery. Who knows how many other bullfinches inhabited the Azores in the past?



From top to bottom: the Eurasian Bullfinch (P. pyrrhula), Azores Bullfinch (P. murina) and the extinct P. crassa. The colors of the newly described species are speculative (adapted from Rando et al. 2017).



Rando, J., Pieper, H., Olson, S. L., Pereira, F. & Alcover, J. 2017. A new extinct species of large bullfinch (Aves: Fringillidae: Pyrrhula) from Graciosa Island (Azores, North Atlantic Ocean). Zootaxa, 4282: 567-583.


Two Crow Hybrid Zones for the Price of One!

The comparison of two Crow hybrid zones reveals that history does not always repeats itself. Genomically, that is.

How species originate and adapt to new environments are some of the central questions in evolutionary biology. With the advent of genomic data, it has become possible to unravel the genomic basis of speciation and adaptation. And hybrid zones can serve as the ideal laboratories for testing new ideas.

One of the most widely studied hybrid zones concerns the contact zone between Hooded Crow (Corvus cornix) and Carion Crow (C. corone) in Europe (you can read more about it here).  A recent study revealed that several genomic regions were not exchanged between these hybridizing species (Poelstra et al. 2014). One of these regions harbored genes related to pigmentation and visual perception. Given that Hooded Crow and Carrion Crow differ in their color patterns, this genomic region could be crucial in the (probably still ongoing) speciation process.



Hooded Crow (front) and Carrion Crow


Thus, the European crow hybrid zone provided important insights into the genomic basis of speciation. But it gets ever better! Did you know that there is another crow hybrid zone in Siberia? In eastern Russia, Hooded Crow is hybridizing with the all-black Eastern Carrion Crow (C. orientalis). An almost perfect replicate of the hybrid zone in Europe!


Eastern Carrion Crow.jpg

An Eastern Carrion Crow


This set-up, two hybrids zones between species at different stages of speciation, provides an excellent opportunity to check whether the same genomic regions are involved. So, Nagarjun Vijay (Uppsala University) and colleagues sequenced and compared 124 genomes of different crow populations. They found that different genomic regions are under selection in the different hybrid zones. In the figure below, you can see the genomic comparison between Hooded Crow and Carrion Crow (above) and between Hooded Crow and Eastern Carrion Crow (below). Pay attention to the red dots, which represent genomic regions that are different between the species. If you move across the genomes, you will see that (with some exceptions) different genomic regions stand out in the two hybrid zones. Clearly, speciation does not repeat itself here.

Crow Genomes

The genomic landscape of crows (adapted from Vijay et al. 2016)



Poelstra, J. W., Vijay, N., Bossu, C. M., Lantz, H., Ryll, B., Muller, I., Baglione, V., Unneberg, P., Wikelski, M., Grabherr, M. G. & Wolf, J. B. W. (2014). The genomic landscape underlying phenotypic integrity in the face of gene flow in crows. Science 344, 1410-1414.

Vijay, N., C. M. Bossu, J. W. Poelstra, M. H. Weissensteiner, A. Suh, A. P. Kryukov and J. B. Wolf (2016). Evolution of heterogeneous genome differentiation across multiple contact zones in a crow species complex. Nature communications 7: 13195.


This paper has been added to the Corvidae page

A Northern and a Southern Perspective on Hybrids between Golden-winged and Blue-winged Warbler

Two recent studies provide insights into the genetics and migration of  two hybridizing Vermivora species. One study turns its attention to the north, whereas the other study focuses on the south.

Over the last 150 years, humans have converted large forest areas into agricultural fields in eastern North America. These habitat changes have facilitated contact between some geographically isolated bird species, often resulting in hybridization.

One example of such secondary contact is the story of Golden-winged (Vermivora chrysoptera) and Blue-winged Warblers (V. pinus). These two species were separated by large patches of forest. The conversion of this forest to agriculture enabled the Blue-Winged Warbler to spread north where it occasionally hybridized the Golden-winged Warbler. The combination of habitat loss and hybridization resulted in the decline of the latter species. The Golden-winged Warbler is now one of the most rapidly declining bird species in North America. Recently, two new studies have been added to the growing literature on the interactions of these small passerines (see here for an overview). One study looks at the final frontier in the north, while the other study focuses on migration to the south.


To The North

Previous studies documented extensive exchange of genetic material between these warblers (a process known as introgression). One exception was Manitoba in Canada. Laurel Moulton (University of Manitoba, Canada) and colleagues reassessed the genetic status of the Golden-winged Warbler in this area. Sampling over 200 birds between 2011 and 2014, they found 10 hybrids. It turns out that there is some genetic introgression in Manitoba, but the levels of introgression are the lowest across the range of Golden-winged Warbler. Hence, Manitoba can be seen as an important refuge for Golden-winged Warbler, where it is safe from the expanding Blue-winged Warbler. For now…


Golden-winged Warbler

A Golden-winged Warbler (from


To The South

Another recent study focused on a mixed population in the Jefferson and Lewis counties of New York. Ruth Bennett (Cornell University, Ithaca, NY) and colleagues attached geo-locators to 10 Golden-winged Warblers, 10 Blue-winged Warblers and 5 hybrids in order to investigate their migratory strategies. Given the genetic similarity between these species, the researchers expected to uncover similar migration routes.

The next year, data from 7 of the 25 birds were recovered. Two Golden-winged Warblers spend their winter in northern Colombia, while three Blue-winged Warblers flew to the Yucatan peninsula in Mexico and the western tip of Cuba. Two hybrids showed an intermediate choice and wintered in Cuba and Nicaragua. These results confirm the notion that migratory behavior is heritable in passerines with genetic hybrids showing intermediate strategies (see here).


Migration warblers

Wintering areas for Blue-winged Warbler (diamonds), Golden-winged Warbler (circles) and their hybrids (squares). Adapted from Bennett et al. (2017).



Bennett, Ruth E, Sara Barker Swarthout, Jeffrey S Bolsinger, Amanda Rodewald, Kenneth V Rosenberg, and Ron Rohrbaugh. 2017. ‘Extreme genetic similarity does not predict non‐breeding distribution of two closely related warblers’, Journal of Field Ornithology.

Moulton, Laurel L, Rachel Vallender, Christian Artuso, and Nicola Koper. 2017. ‘The final frontier: early-stage genetic introgression and hybrid habitat use in the northwestern extent of the Golden-winged Warbler breeding range’, Conservation Genetics: 1-7.


The papers have been added to the already quite extensive Parulidae page.

The Ecological Succession Story of Hybridizing Bluebirds

Avian hybrid zones have been studied extensively for decades. You would think that ornithologists looked at these zones from all possible angles. Nonetheless, Renée A. Duckworth and Georgy A. Semenov provide a fresh perspective on a particular hybrid zone between two Sialia species.

Ecological succession refers to the situation where the species composition of a community changes over time. Mostly, succession occurs after an environmental disturbance, such as a forest fire. The resulting habitat is first colonized by the most dispersive species. Later on, other species – often better competitors – invade and start to replace the early arrivers.

This is what happened in the northwestern United States.  The open meadows of Montana are not the ideal habitat for bluebirds (genus Sialia), but the placement of artificial nest boxes provided the ideal conditions for these cavity breeders. So, the introduction of nestboxes can be considered the ‘environmental disturbance’. The first species to take advantage of these new nesting places was the  Mountain Bluebird (S. currucoides). The more aggressive Western Bluebirds (S. mexicana) were delayed in their arrival, but once they showed up, their numbers increased rapidly.

Using data from 10 populations from 2001 to 2014, Duckworth and Semenov investigated the occurrence of matings between these two Bluebird species during different stages of the ecological succession. In addition, to check whether these heterospecific pairs actually produced hybrids (you never know if there are extra-pair copulations!), they also looked into the genetics of these birds using microsatellites.



The early arriving Mountain Bluebird (left) and the delayed, more aggressive Western Bluebird


The results show that heterospecific matings only occurred during the early stages of succession. This is in accordance with Hubb’s principle, which states that hybridization is more likely when one species is rare. In this case, the first wave of invading Western Bluebirds were outnumbered by Mountain Bluebirds. Unable to find another Western Bluebird to mate with, they ‘settled’ for a Mountain Bluebird. Later in the succession, the number of Western Bluebirds increased and the chances of hybridization diminished.

Although the frequency of hybridization seems to decline during the ecological succession, the genetic effects of interbreeding are still measurable in later generations. This could have important evolutionary consequences for these species.


Duckworth, R. A. & Semenov, G. A. (2017). Hybridization Associated with Cycles of Ecological Succession in a Passerine Bird. The American Naturalist 190.


Thanks to Renée A. Duckworth for sending me a copy of this paper. The information has been added to the Turdidae page.

Hybrid Geese: A Trilogy of Papers

With the publication of ‘A History of Hybrids? Genomic Patterns of Introgression in the True Geese’ in BMC Evolutionary Biology, the three goose papers from my PhD thesis have made it into scientific journals. The trilogy is complete, but the story continues…

During my PhD, I studied the evolutionary history of the True Geese. This bird group contains about 17 species (depending on which authority you follow) and is traditionally divided into two genera: Anser and Branta. At the start of my PhD, I was surprised to find out that the phylogeny (i.e. evolutionary tree) of the geese was still unresolved. The failure to resolve the relationships between these bird species is probably due to high levels of hybridization. My goal was to solve this phylogenetic conundrum and further explore the influence of hybridization during the evolutionary history of the True Geese.


Part 1: Goose Hybrids

Although the main focus of my research was to quantify the effects of hybridization on an evolutionary timescale, I wanted to know the current state of events. How often do birders see hybrid geese? Which species are interbreeding? Are these hybrids fertile? And why does a goose choose a partner of another species? These questions formed the basis for part one of the goose trilogy. This first story was published in Frontiers in Zoology, entitled ‘Hybridization in Geese: A Review’.

It turns out that the majority of goose species have interbred at some point (in captivity or in the wild). Hybrids are thus common on a species-level, but rare on a per-individual level. The origin of particular goose hybrids is difficult to deduce but several mechanisms, such as interspecific nest parasitism and extra-pair copulations, are possible. The different mechanisms are not mutually exclusive and it is currently not possible to discriminate between these mechanisms without quantitative data.

Most hybrid geese are fertile; only in crosses between distantly related species do female hybrids become sterile. This fertility pattern, which is in line with Haldane’s Rule, may facilitate interspecific gene flow between closely related species. This finding is important for the other stories in the goose trilogy.

nest parasitism


Part 2: A Tree of Geese

Before I could investigate the role of hybridization in goose evolution, I needed a proper phylogenetic framework. The construction of this framework was the focus of my second story, which was published in Molecular Phylogenetics and Evolution under the title ‘A Tree of Geese: A Phylogenomic Perspective on the Evolutionary History of True Geese‘.

For this study, I collected blood samples from all goose species. Sequencing the whole genome of these species provided me with a huge amount of data to resolve the phylogenetic tree of this bird group. I won’t bother you with the technical details (e.g., we opted for an exon-based approach with both concatenation and consensus analyses). Let’s jump straight to the main results!

The split between Anser and Branta was already well-established, but the relationships within these genera were contentious. Using whole genome data, I was able to resolve the phylogenetic relationships between the different goose species.

Within the genus Branta (commonly referred to as the Black Geese) there is a group of White-cheeked Geese – Canada Goose (B. canadensis), Cackling Goose (B. hutchinsii), Barnacle Goose (B. leucopsis) and Hawaiian Goose (B. sandvicensis) – and two basal splits – leading to Brent Goose (B. bernicla) and Red-breasted Goose (B. ruficollis).

In the genus Anser, the most basal split leads to the morphologically divergent Bar-headed Goose (A. indicus). Next, two main groups can be recognised: the White Geese – Snow Goose (A. caerulescens), Ross’ Goose (A. rossii) and Emperor Goose (A. canagicus) – and the Grey Geese – Greylag Goose (A. anser), Swan Goose (A. cygnoides), the White-fronted Geese (A. albifrons and A. erythropus) and the Bean Goose complex (A. fabalis, A. serrirostris and A. brachyrhynchus).

A molecular clock analysis indicated that the majority of speciation events took place at the end of the Pliocene. The approximate date of diversification coincides with the beginning of a period of climatic oscillations between 3.2 and 1.9 million years ago. This period was part of a fast global cooling trend, following the closure of the Panama Seaway and the uplifting of the Tibetan Plateau around four million years ago. This resulted in the formation of permanent Northern Hemisphere ice sheets, the establishment of a circumpolar tundra belt and the emergence of temperate grasslands, which opened up new ecological niches in which new groups of animals and plants were able to spread. The tundra habitat serves as breeding ground for geese, while the temperate grasslands act as wintering grounds where mate choice takes place. Moreover, these tundra and grassland habitats provided ample opportunity for geese to explore new ecological niches and diversify in beak morphology.

A Tree of Geese

More importantly, the comparison of different gene trees revealed that different genes tell different stories. This observation, called gene tree discordance, can be caused by rapid speciation (leading to a phenomenon known as incomplete lineage sorting or ILS) and hybridization. Disentangling the contributions of ILS and hybridization is the focus of the third story.


Part 3: A History of Hybrids

And so we arrive at the final story in this trilogy where I explored the role of hybridization during the evolutionary history of the True Geese. As mentioned in the introduction, this story was published in BMC Evolutionary Biology, entitled ‘A History of Hybrids? Genomic Patterns of Introgression in the True Geese‘.

I found indications for ancient gene flow during the diversification of the True Geese and I was able to pinpoint several putative hybridization events. Specifically, in the genus Branta, both the ancestor of the White-cheeked Geese (Hawaiian Goose, Canada Goose, Cackling Goose and Barnacle Goose) and the ancestor of the Brent Goose hybridized with Red-breasted Goose.

The reconstruction of historical effective population sizes shows that most species experienced a steady increase during the Pliocene and Pleistocene (in agreement with the conclusions from story 2). These large effective population sizes might have facilitated contact between diverging goose species, resulting in the establishment of hybrid zones and consequent gene flow.

I can definitely conclude that the evolution of goose species follows a complex speciation model high levels of gene flow during species diversification. Unfortunately, I did not have the data to determine whether this gene flow is the outcome of (repeated) secondary contact or divergence-with-gene-flow. This warrants a population genomic approach whereby multiple individuals of one population are sequenced. In fact, this is exactly what I plan to do during my postdoc with Hans Ellegren at Uppsala University.

To be continued…

Goose Demography.jpg



Ottenburghs, J., van Hooft, P., van Wieren, S.E., Ydenberg, R.C. & Prins, H.H.T. (2016). Hybridization in Geese: A Review. Frontiers in Zoology. 13:20 DOI: 10.1186/s12983-016-0153-1

Ottenburghs, J., Megens, H.-J., Kraus, R.H.S., Madsen, O., van Hooft, P., van Wieren, S.E., Crooijmans, R.P.M.A., Ydenberg, R.C., Groenen, M.A.M. & Prins, H.H.T. (2016). A Tree of Geese: A Phylogenomic Perspective on the Evolutionary History of True Geese. Molecular Phylogenetics and Evolution. 101:303-313  doi:10.1016/j.ympev.2016.05.021

Ottenburghs, J., Megens, H.-J., Kraus, R.H.S., van Hooft, P., van Wieren, S.E., Crooijmans, R.P.M.A., Ydenberg, R.C., Groenen, M.A.M. & Prins, H.H.T. (2017). A History of Hybrids? Genomic Patterns of Introgression in the True Geese. BMC Evolutionary Biology. 17:201



Throwback Thursday: Observations of Red-shafted and Yellow-shafted Flickers in a 1893 letter to Science

It’s Thursday, so time for an old avian hybrids paper! This week: a short letter to Science on hybrid woodpeckers.

Being a scientist in the 1800s must have been great. Nowadays, researchers struggle to get something published in high ranking journals, such as Science or Nature. Back in the days, you could just send a letter to the editor of those journals and you would have a reasonable chance of getting published.

In 1893, Alvah Eaton reacted to a summary of hybridization in the genus Colaptes in a previous edition of Science. Here is the entire letter:


A letter in Science based on a few presumed hybrids between Red-shafted Flicker (C. cafer) and Yellow-shafted Flicker (C. auratus). This would be unthinkable nowadays. However, these two woodpecker species have become one of the model systems for avian hybridization in North America. You can read more about them here.


Yellow-shafted and Red-shafted Flicker

On a side note, the letter following the piece by Eaton shows how scientists communicated before the arrival of the internet. Want to know how to study ants? Just send a letter to Science!



Eaton, A. A. 1893. Hybridism in Genus Colaptes. Science (New York, N.Y.), 21: 25-25.


Throwback Thursday: Strange Swallows from 1902

It’s Thurday! So, let’s dive into the avian hybrids literature and fish out a golden oldie. Today: hybrid swallows.

On June 14, 1893, in El Paso County (Texas, US) Edgar A. Mearns found a pair of swallows that were building a nest on an old building. He noticed that ‘the nest was similar to that of Barn Swallow, having the entrance at the top.’ And as any good ornithologist those days would do, he shot both birds.

The male turned out to be a Barn Swallow (Hirundo rustica), while the female was a hybrid between Barn Swallow and Cliff Swallow (Petrochelidon lunifrons). In a short article, published in The Auk, Mearns describes this peculiar cross, but unfortunately without any pictures or drawings. Luckily, I found some recent pictures online (click here for more):


barn x cliff

Barn Swallow (left), Cliff Swallow (right) and a presumed hybrid in the center.



Mearns, E. A. 1902. Description of a hybrid between the Barn and Cliff swallows. The Auk, 19: 73-74.



Some Hybrid Woodpeckers from North and South America

Today, I would like to discuss two papers on hybridization in woodpeckers. The first paper provides the description of a cross between two species in Paraguay. The second study concerns a genomic analysis of hybrid zones between three Sphyrapicus species.


Paraguayan Peckers

Andrés Oscar Contreras Chialchia and Paul Smith provide a detailed description of a hybrid between Cream-backed Woodpecker (Campephilus leucopogon) and Crimson-crested Woodpecker (C. melanoleucus), two species that co-occur along the banks of the Paraná River in Paraguay. Because one picture says more than a thousand words: here is the hybrid specimen alongside the parental species. You can clearly recognize traits of both species. For example, the black-and-white spot on the cheek and the creamy back of the Cream-backed Woodpecker and the striped belly of the Crimson-crested Woodpecker.

Hybrid Woodpecker.png

Top: the hybrid specimen. Left: Cream-backed Woodpecker. Right: Crimson-crested Woodpecker


Sapsucker Hybrid Zones

Three species of Sphyrapicus woodpeckers – Red-breasted Sapsucker (S. ruber), Red-naped Sapsucker (S. nuchalis) and Yellow-bellied Sapsucker (S. varius) – interbreed in several hybrid zones. Red-breasted and Red-naped Sapsucker are more closely related to each other compared to the third species. This situation provides an excellent setting to study the build-up of reproductive isolation and genetic differentiation over time.

Christine Grossen and her colleagues examined over 30 000 genetic markers (Single Nucleotide Polymorphisms or SNPs) along hybrid zones in the Coast Mountains and Rocky Montains. The genomic analyses showed that the tree species are clearly distinct with a small number of hybrids in each hybrid zone. This indicates that there is moderately strong reproductive isolation between them.


hybrid sapsuckers

The three species: Red-naped Sapsucker, Red-breasted Sap-sucker and Yellow-bellied Sapsucker (from left to right)


There were no large regions of differentiation in the genome (so-called ‘genomic islands of differentiation’). However, the authors uncovered 19 small regions of differentiation, some of which were shared between species. One of those regions contained a candidate locus associated with plumage, which could contribute to reproductive isolation.

The authors conclude that ‘[o]ur comparative analysis of species pairs of different age and their hybrid zones showed that moderately strong reproductive isolation can occur with little genomic differentiation, but that reproductive isolation is incomplete even with much greater genomic differentiation, implying there are long periods of time when hybridization is possible if diverging populations are in geographic contact.’



Chialchia, A. O. C. & Smith, P. (2014). A notable hybrid woodpecker (Campephilus leucopogon x C. melanoleucus)(Aves: Picidae) from Paraguay. ORNITOLOGIA NEOTROPICAL 25, 459-464.

Grossen, C., Seneviratne, S. S., Croll, D. & Irwin, D. E. (2016). Strong reproductive isolation and narrow genomic tracts of differentiation among three woodpecker species in secondary contact. Molecular ecology 25, 4247-4266.


Both papers have been added to the Piciformes page.

Throwback Thursday: A Hybrid Quail That Tried to Phone Home

Numerous papers on avian hybridization are published each month, applying the newest genomic and statistical techniques. But occasionally, one needs to escape to simpler times. That is the idea of this Throwback Thursday section on the blog: I dive into my huge collection of literature on avian hybridization and pick out a remarkable paper. Today concerns a short piece by M.E. Peck, published in The Condor in 1911. The short title almost says it all: A Hybrid Quail.

The bird in question is probably a cross between Mountain Quail (Oreortyx pictus) and California Quail (Callipepla californicus, in the paper referred to with the older generic name Lophortyx). The hybrid was found in Oregon, where it ‘was killed, apparently, by flying against a telephone wire.’ Mr. Peck himself collected the bird and mounted it ‘while fresh’. The morphological analysis shows that ‘[i]f this hybrid be compared point by point with the two parent forms, there will be found a remarkably even balance of characters derived from each; this is especially true of the coloration.’ Here is a – unfortunately black-and-white – picture of the mounted specimen:

Hybrid Quail

And for comparison, the two species that produced this fine specimen.


Mountain Quail (left) and California Quail

Finally, I would like to share the title page of this short paper. It is amazing how nice the old editions of these journals, such as The Condor, looked those days.



Peck, M. 1911. A hybrid quail. The Condor, 13: 149-151.

The Superb Bird-of-Paradise and the ‘Dancing Species Concept’

Time for something different, but actually closely related to hybridization: species concepts. Today, I came across a press release from the Cornell Lab of Ornithology. It concerns the Superb Bird-of-Paradise (Lophorina superba), a bird species endemic to New Guinea and known for its peculiar mating display. It can be best described as a jumping black and fluorescent blue smiley-face (click on the picture to see the courtship display in action or click here).




Scientist Ed Scholes and photographer Tim Laman documented this courtship display for two populations: the western population in the Arfak Mountains and the more common population that occurs all across the island. They noted striking differences between birds from these populations. Scholes remarks: “The courtship dance is different. The vocalizations are different. Even the shape of the displaying male is different.” Pictures show that the shape is indeed different. The Western male has a crescent shape, while the common male is more oval-shaped.


superb pictures

Differences in shape between Western male (left, crescent shape) and widespread male (right, oval shape).


Based on their observations, Scholes and Laman both believe that the Western population should be considered a separate species. When I read this, I had to frown. Can you really describe a new species based on dancing? Then taxonomists could add an extra species concept to the long list already available: the Dancing Species Concept. According to this species concept, I would be considered member of a separate species compared to some of my fellow Homo sapiens. My dancing moves are – euphemistically speaking – not so good…

Of course, I am writing this jokingly.  The distinct dancing behaviors of Superb Birds-of-Paradise fit within the Species Recognition Concept. The display ensures that females chose the ‘right’ species. It would be interesting to see how females from the Western population respond to displaying males from the widespread population. If they ignoring the jumping smiley, it would provide extra evidence for the description of a new species.

In fact, a recent genetic study showed that the Western population is genetically distinct from the widespread population. “The timing of this DNA-based study is perfect,” said Ed Scholes, “because it is great to have our field observations supported by solid genetic evidence. We really appreciate this in-depth study of the evolutionary relationships among the different forms of Superb Bird-of-Paradise.” To be continued.




Irestedt, M., Batalha-Filho, H., Ericson, P. G., Christidis, L. & Schodde, R. 2017. Phylogeny, biogeography and taxonomic consequences in a bird-of-paradise species complex, Lophorina–Ptiloris (Aves: Paradisaeidae). Zoological Journal of the Linnean Society.