The Systematist 34

The Systematist 34

The Systematist Newsletter of the Systematics Association Number 34 2012 www.systass.org ISSN 1744-5701 • Cichlid fish and the micro-macroevolution continuum in the origin of species diversity • Foundation Monographs - accelerating the pace of taxonomy • One species or three? The Azorean butterfly-orchids • Twitter for systematists • Celebrating systematics - 75 years of the Systematics Association • Young Systematists Forum 2011 • Cultivating common ground: biology and the humanities • Inspirations: Anne Yoder Book Reviews Celebrating systematics 75 years of the Systematics Association n the 20th June this year a special event reception, (I hoped not too many would notice the sign took place at the Natural History ‘The end of the world is nigh?’) I then saw humans Museum to celebrate 75 years of the exhibited alongside a moa skeleton—a bird which was Systematics Association. What better hunted to extinction. And there we were treated to a way to mark such an occasion than an delicious hot buffet and more refreshments. Oauthoritative, inspirational and animated conversation between Sir David Attenborough and Professor Richard So what about the future and direction of the Systematics Fortey? These generous gentlemen thoroughly Association? That will no doubt depend on many things, entertained a large audience with tales of some of the but I believe that the now and the future depend on the characters linked to the Association in one capacity or following fundamental aspects. I would argue that we are another that they had known, from Sir Julian Huxley living in a new age of discovery. Never before has it been through Humphrey Greenwood, Arthur Cain and Ernst possible to study the diversity of the world in all its Mayr amongst others. Before the conversation, David minutiae with the ability to explore the planet with the Williams started the evening with a history of the brilliant techniques that we have available to us. The Systematics Association. No-one else could present a Systematics Association can and should play a vital and history in such an unusual, fresh, provocative and lateral leading role in both documenting and synthesising life on way, bringing both the subject and some of the colourful Earth. The Systematics Association also needs to become personalities to life. Every Society comes with its an excellent communicator of what it does and how it characters, scandal and intrigue. does it. Finally, we must have a new generation of people to take these ideas forward. How many evenings have two receptions? After the history, a reception provided the opportunity to connect We need systematists and systematics more than ever and reconnect with colleagues and friends. Amongst the before. crowd there were former Presidents of the Association, three generations of one family and plenty of young people, many of whom have contributed to the Young Systematist’s Forum in recent times. After the Attenborough and Fortey conversation a second reception commenced in the gallery ‘From the beginning’ next to the Flett theatre. What an excellent setting full of illustrations of such creatures as the wonderfully named Hallucigenia and fossils including ammonites, a huge oceanic predator, a plant eating reptile, mammoth bones and so on. At the far end of the gallery where we all From left to right: Richard Fortey, Sir David Attenborough entered for the second and Eleanor Adamson (copyright Eleanor Adamson) Cover illustration: an as yet un-described new species of Ipomoea from the Andes of Bolivia (copyright R. Scotland) The Systematist 2012 No. 34 2 Cichlid fish and the micro- macroevolution continuum in the origin of species diversity Ole Seehausen EAWAG Centre for Ecology, Evolution and Biogeochemistry, Kastanienbaum, Switzerland Institute of Ecology and Evolution, University of Bern, Switzerland Cichlid fish diversity – age and distribution Introduction Cichlid fish species richness is highly unevenly erhaps the two most fundamental distributed in space. It is actually low everywhere except challenges to our understanding of species in tropical Africa, Madagascar and tropical South and diversity are to explain, first, why species Mesoamerica (table 1). Respectively, 450 and 110 exist and second, why some species species are known from tropical South- and multiply a lot more than others. Why do Mesoamerica. The former number is not very high given some taxa undergo large evolutionary the large area occupied in South-America, and is easily Pradiations, diversifying into many and varied species, matched by several other South American freshwater fish while others do not? This essay is about cichlid fish families. In Africa and the Americas, the distribution of diversification and what investigating it may teach us species richness in the cichlid fish family adheres to the about that second question. latitudinal species richness gradient (Figure 1), but the exceptional species richness of cichlid fish only Both environmental factors such as the diversity of manifests itself in tropical Africa, where there are some available resources, habitats or climates, and lineage- 1575 known species. 1400 of these are endemic to single specific traits, such as behavioural or morphological equatorial lakes, whereas lakes in subtropical Africa traits, and perhaps genetic architectures, may influence contain endemic species much less frequently, and only the rates and extent of biological diversification. The some 175 species are known from all the African rivers large radiations of cichlid fishes in the African Great together, again predominantly in the tropical parts of the Lakes, Victoria, Tanganyika and Malawi, provide the continent. In Madagascar, Meso- and South America on most dramatic known cases of species diversification. the other hand, most of the diversity occurs in rivers, and That cichlids provide striking evidence for evolutionary stasis too and for failure to diversify is underappreciated. I argue that it is the combination of both within one taxon that makes cichlids so very suitable for addressing questions about biological diversification. Thirteen percent of all species of freshwater fish are cichlid fish Cichlids are perch-like fish, distributed in freshwaters of the tropics and subtropics. With some 1300 validly described species but at least 2200 species known, they are the second most diverse family of freshwater fish after the cyprinids (2700 described species). It also is the third most species rich family of all fish, (there are 2000 described species of mostly marine gobies, Gobiidae), and probably of all vertebrate animals. At least 13% of all species of freshwater fish are cichlid fish! Cichlids have fascinated biologists and aquarist-naturalists alike for over a century because of their extraordinary diversity in Figure 1. The continental distribution of cichlid fish morphology, ecology, colour and behaviour. Their species alpha-diversity. Approximate numbers of exceptional species proliferation and accumulation of species coexisting within area plots of 10 ×10 km sympatric species diversity, may both be unparalleled (Seehausen, unpublished). amongst vertebrate animals. The Systematist 2012 No. 34 3 lake endemism is rare. lineage of cichlid fish. Moreover, at least some of the large radiations are apparently derived from several such Molecular phylogenies suggest that cichlids are lineages that hybridised (Joyce et al. 2005; Joyce et al. monophyletic (Streelman and Karl 1997; Sparks and 2011). Smith 2004) and that with the exception of Madagascar, cichlid faunas of major biogeographical regions also Species are real even in the most rapid cichlid make monophyletic clades, the branching order among radiations which is congruent with the breakup of Gondwana (Sparks 2004; Sparks and Smith 2004). If this was Adaptive radiation is usually thought to be associated suggestive of a Mesozoic origin during the Late Jurassic with speciation, but the evolution of intraspecific or Early Cretaceous, the oldest known cichlid fossils, polymorphisms without speciation could be an Mahengechromis from Tanzania and Proterocara from alternative mechanism. The cichlid fish in Lake Victoria Argentina, are dated only to the Eocene (46 MYA and are perhaps the most incredible example of a very recent 33.9–5.8 MYA; (Murray 2001; Malabarba et al. 2006). rapid adaptive radiation, with 600+ species that arose Even the earliest fossils of all the labroid fish within the past 15–100,000 years. Key questions about (surfperches, damselfish, wrasses and cichlid fish, now the rapid origin of this diversity include those about considered a polyphyletic group (Santini et al. 2009) are speciation versus polymorphism, whether species persist only about 65 MY old (Lundberg 1993). on evolutionary time scales, and whether speciation typically occurs in small isolated or in large connected If the earliest cichlid fossils were approximately populations. Studying more than 300 individuals from coincident with the origin of the family, their present 105 putative species in a radiation-wide AFLP genome distribution must instead be explained by intercontinental scan, Bezault et al. (2011) demonstrated pervasive marine dispersal (Vences et al. 2001). To resolve this signatures of speciation supporting the classical model of conflict, Genner et al. (2007) calibrated a relaxed adaptive radiation. A positive relationship between the molecular clock with geological estimates for the ages of age of lakes (within the Lake Victoria region) and the either Gondwanan

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