by Greg Mayer
Jerry has long insisted–quite rightly, to my mind– that biogeographic evidence was critical in leading Darwin to accepting descent with modification, and that to this day it is among the most pedagogically effective tools in teaching about evolution. Darwin’s visit to the Galapagos Islands is the most heralded of his encounters with island biota, and I would argue that his visit to the Falkland Islands was also quite formative of his views. It is less well known that HMS Beagle also called at Tenerife in the Canary islands but that, much to Darwin’s disappointment– for he had long wished to visit the island– the crew was not allowed to land, due to a cholera scare. Despite Darwin’s disappointment, many of the phenomena of island life that so impressed him can be observed in the biota of the Canaries; and we can look forward to Jerry’s return, when he’ll be able to share more photographs of the islands and their biota.
As Jerry has already noted, these are volcanic islands which emerged from the sea and have never been connected to the African mainland to the east. They are thus, biogeographically speaking, oceanic islands: they have received their biota via what Darwin called occasional means of transport— floating, flying, or swimming. The vertebrate fauna of the islands thus consists of birds, bats, lizards, a few now extinct rats/mice, and a single species of shrew. There are no native large land mammals, no snakes, and no amphibians. Endemism (species found only in the Canaries) is quite high, especially among the lizards and land mammals.
The lizards include skinks (Chalcides), geckos (Tarentola), and “true lizards” (Gallotia; they are in the family Lacertidae, lacerta meaning lizard in Latin, and thus are the “true” lizards). All of these have their closest relatives in North Africa and the Mediterranean region, from whence they came. The most interesting lizards by far are those of the genus Gallotia.
This genus is endemic to the Canaries, and is found throughout the archipelago. Some species/populations are endangered or already extinct. There can be up to three species on an island– small, medium, and large– thus coming closest of any to an adaptive radiation; most endemism in the Canaries is of representative forms on each island, rather than a genuine splitting of lineages leading to multiple related species sharing the same island (as Darwin’s finches in the Galapagos do).
The Canaries fall in the Palearctic zoogeographic region, the affinities of most of their fauna being with North Africa and Europe. The Mediterranean Sea is only a partial zoogeographic barrier, and North Africa lies in the Palearctic region (which extends to Japan and Siberia), rather than the Ethiopian region, which comprises sub-Saharan Africa. Within the Canaries, there’s quite a bit of ecological and climatic variation. The eastern islands are dry and desert-like, while the western islands are wetter, with a vegetational zonation of scrub on the coasts with pine forest and the distinctive laurel forest at higher elevations, with an alpine scrub at the very highest elevations.
The following is an annotated bibliography for those who might wish to learn more about the Canaries. It is somewhat idiosyncratic, reflecting my own interests and what I happen to have in my own library, rather than any comprehensive review of the literature.
Books for a broad audience
Bannerman, D.A. and W.M. Bannerman. 1963-1968. Birds of the Atlantic Islands. 4 vols. Oliver and Boyd, Edinburgh. It’s been a while since I’ve looked at a copy, but this is a classic, with some beautiful plates and a comprehensive account of the avifauna as known at the time. The Canaries are volume 1.
Bowler, J. 2018. Wildlife of Madeira and the Canary Islands. Princeton University Press, Princeton, NJ. The only general guide to the Canaries I’ve seen, but fairly disappointing. The field guide illustrations are photographs, many of which seem inadequate for identification; scientific names are relegated to an appendix; the author misunderstands concepts of island biology; and there is no overall appreciation of the islands’ biodiversity and its origins. Nonetheless, I think it is a must have if you ever make a visit.
Garcia-del-Rey, E. 2018. Birds of the Canary Islands. Christopher Helm, London. I have not seen a copy of this, but the available extracts online show it to be a well-done modern bird guide by a Canarian with fine illustrations. Although general European field guides sometimes include the Canaries, you’d want to have this book with you if visiting.
More technical articles
Most of these, depending on your library access, will be paywalled. Discreet inquiry may yield a copy.
Böhme, W., and R. Hutterer, eds. 1985. Ergebnisse des 1. Symposiums “Herpetologia Canariensis.” Bonner Zoologische Beitrage 36(3-4): 233-606. Zoologischen Forschunginstitut und Museum Alexander Koenig, Bonn. (Biodiversity Heritage Library) A collection of papers in German, Spanish, and English that focuses on herps, but has more general articles as well. This was published shortly after some of the exciting discoveries of living giant lizards; see Maca-Meyer et al. (2003) for some more recent work.
Boulenger, G.A. 1891. On Simonyi’s Lizard, Lacerta simonyi. Proceedings of the Zoological Society of London 1891(1):201-202. (Biodiversity Heritage Library) A technical description, with illustrations, of a specimen that had been in the London Zoo.
Grant, P.R. 1979a. Ecological and morphological variation of Canary Island blue tits, Parus caeruleus (Aves: Paridae). Biological Journal of the Linnean Society 11:103-129. On some of the Canaries, blue tits, in the absence of the pine-dwelling coal tit, have shifted into pine forest, and their beaks have become adapted to this foraging substrate.
Grant, P.R. 1979b. Evolution of the chaffinch, Fringilla coelebs, on the Atlantic Islands. Biological Journal of the Linnean Society 11:301-332. Presents morphological evidence for ecological character displacement between common and blue chaffinches in the Canary Islands, and that Azores common chaffinches have evolved a more generalized, intermediate, morphology.
Illera, J.C., J.C. Rando, D.S. Richardson, and B.C. Emerson. 2012. Age, origins and extinctions of the avifauna of Macaronesia: a synthesis of phylogenetic and fossil information. Quaternary Science Reviews 50:14-22. Reviews recent molecular phylogenetic work on the birds of these islands, finding that most extant birds are recent (<4 Mya) colonists, even though the islands are much older (ca. 30 Mya).
Lack, D. and H.N. Southern. 1949. Birds on Tenerife. Ibis 91:607-626. A classic paper pointing out many interesting problems of ecomorphological adaptation and distribution, particularly in chaffinches and tits, which have been studied by later workers, e.g. Grant (1979a,b). Less technical and quite readable.
Maca-Meyer, N., S. Carranza, J.C. Rando, E.N. Arnold, and V.M. Cabrera. 2003. Status and relationships of the extinct giant Canary Island lizard Gallotia goliath (Reptilia: Lacertidae), assessed using ancient mtDNA from its mummified remains. Biological Journal of the Linnean Society 80: 659-670. Uses ancient DNA to investigate the relationships of the Canary-endemic genus Gallotia.