The Fossil Record and Biogeography of the Cichlidae (Actinopterygii: Labroidei)
Total Page：16
File Type：pdf, Size：1020Kb
Biological Journal of the Linnean Society (2001), 74: 517-532. With 4 figures doi:10.1006/bijl.2001.0599, available online at http://www.idealibrary.com on IDEM® The fossil record and biogeography of the Cichlidae (Actinopterygii: Labroidei) ALISON M. MURRAY* Redpath Museum, McGill University, 859 Sherbrooke St West, Montreal, QC, H3A 2K6, Canada Received 20 March 2001; accepted for publication 17 July 2001 The family Cichlidae is a large group of tropical fishes in the order Perciformes, with an estimated number of living species exceeding 1400. The modern distribution of the family Cichlidae is predominantly in fresh waters of Central and South America, Africa, Madagascar, India and the Middle East, with fossil members known from Africa, Saudi Arabia, the Levant, Europe, South America and Haiti. Many authors have referred to the distribution as being Gondwanan and have postulated that cichlids originated over 130 million years ago, in the Early Cretaceous. However, the suggested evidence for an Early Cretaceous origin of cichlids is equally or more compatible with a much younger age of origin. Based on the biology and distribution of modern and fossil cichlids, it is more probable that they arose less than 65 million years ago, in the Early Tertiary, and crossed marine waters to attain their current distribution. © 2001 The Linnean Society of London ADDITIONAL KEY WORDS: Africa - Asia - dispersal - Europe - Neotropics - palaeobiogeography - salinity tolerance. INTRODUCTION 1300 (Nelson, 1994), 1400 (Kullander &Nijssen, 1989), or more, with the majority being the species that have Two schools of thought regarding the origin of disjunct radiated rapidly in the East African Great Lakes. distributions dominate in the literature. On the one The Early Cretaceous origin for the family Cichlidae hand are those biogeographers who suggest that dis- suggested by Stiassny (1987, 1991) was in part based peral across a barrier allowed organisms to exploit upon the assertion that the distribution of cichlids new areas and speciate, while on the other are those conformed to a Gondwanan pattern, and therefore who attribute disjunct distributions to the splitting of must have originated before the breakup of the con a larger ancestral distribution by a vicariant event. tinents. Although Greenwood (1983) had previously Although vicariant events may explain many dis suggested that cichlids may have undergone marine tributions, dispersal events also have been significant dispersals and were unlikely to have been present in for some current distributions of organisms (e.g. on “Gondwana times”, and Stiassny & Raminosoa (1994) oceanic islands). The current distribution of cichlids later stated that the presence of cichlids in Madagascar has been attributed to vicariant events, leading to might be best explained by a post-rift (i.e. marine an extremely lengthy history for the family being or land bridge) dispersal, the suggested ‘Gondwanan’ postulated (e.g. Stiassny, 1987, 1991; Zardoya et al., distribution of the Cichlidae and their implied Early 1996; Farias, Schneider & Sampaio, 1999). Cretaceous origin is reiterated in the literature (e.g. Extant cichlids are found in Central and South Greenwood, 1994; Leveque, 1997). Farias et al. (1999) America (with one species reaching into Texas), the also stated that cichlids had an “ancestral Gondwana- West Indies, Africa, Madagascar, the Levant, Syria, wide range” and that “a simple vicariant hypothesis” Sri Lanka, coastal India and Iran (Fig. 1). The number explained the distribution of this family, based on their of Recent species in the family is estimated at about phylogeny in which the South American and African cichlids form reciprocal monophyletic sister groups (but see Stiassny, 1991 for an alternate opinion in which the African cichlids are polyphyletic). The as * Current address: Research Division, Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, ON K1P6P4, sumed age of origin has been further lengthened by Canada. E-mail: [email protected] Zardoya et al. (1996), Streelman et al. (1998) and 517 0024-4066/01/120517 + 16 $35.00/0 © 2001 The Linnean Society of London 518 A. M. MURRAY Figure 1. Distribution of fossil and modern cichlids. Shaded areas are current distribution and lighter grey area indicates disjunct water bodies within the area. Modified from Stiassny (1991: fig. 1.1) with information from Coad (1982). Numbers refer to fossil specimens and localities listed in Table 1. Farias et al. (1999), who have suggested a history of are often related to the geographical position of con over 130 million years (Myr) for the Cichlidae, based tinental land masses at certain points in their geo on the separation of Madagascar from the Gondwanan logical history. In the early part of the Mesozoic, most continent by a marine barrier. This extremely remote of the earth’s land mass was coalesced in a single origin of cichlids is not supported by the fossil record. continent. This single continental mass had split into The earliest known cichlids are about 45 Myr old a northern part, Laurasia, separated by the Tethys (Murray, 2000b), which would suggest a gap in the Sea from the southern part, Gondwana, by the end of fossil record of more than 80 Myr if the age of origin the Middle Jurassic, about 160 million years ago (Mya) suggested by Farias et al. (1999) were correct. Such a (Smith, Smith & Funnel, 1994). Gondwana included gap is not evident in the fossil records of two other the lands of South America, Africa, India, Madagascar, fish groups, the freshwater osteoglossomorphs and ch- Australia, Antarctica and Arabia. These land masses aracoids. The former has a fossil record from the Jur maintained at least minor connections until roughly assic (Li & Wilson, 1996) and the latter from the 120 Mya, by which time Gondwana had split into Late Cretaceous (Murray, 2000a), with representatives three masses: (1) Africa/Arabia + South America, (2) known from all the following epochs. Madagascar + India, and (3) Australia + Antarctica. Furthermore, the phylogenetic relationships and Cichlids are found in the two former, but not Australia/ current distribution of the Cichlidae can be equally Antarctica. well interpreted based on dispersal events. Hypotheses If cichlids truly had a Gondwanan distribution 130 of an Early Cretaceous origin of cichlids rests on two Mya, they should also have been in Australia, which questionable assumptions: that the distribution of cich- was at a similar latitute to India/Madagascar. Al lids conforms to a Gondwanan pattern and that cichlids though the freshwater fish fauna of Australia is de are incapable of dispersal through salt waters. pauperate and highly endemic (Morgan, Gill & Potter, 1998), it does share some taxa with Africa (e.g. Os- teoglossomorpha, Galaxiidae, and lungfishes), all of GONDWANAN DISTRIBUTION which have a fossil record dating from the Cretaceous The distributions of modern organisms, particularly or earlier. However, neither living nor fossil cichlids those that are terrestrial or confined to fresh waters, are known from Australia. Furthermore, if cichlids CICHLID BIOGEOGRAPHY 519 were confined to a strictly Gondwanan distribution, Democratic Republic of the Congo, and O. amphimelas they would not now be in the West Indies which did of lakes Manyara and Eyasi, which have high pro not rise above sea level until the late Miocene (Smith portions of sodium chloride (Trewavas, 1983). Clearly et al., 1994) perhaps 7 or 8 Mya. Clearly, the dis there are many examples of salinity tolerance in cichlid tribution oi the Cichlidae does not include some oi the fishes, and consequently there is no reason to believe Gondwanan land mass, but does include lands that that salt water was a barrier to cichlid dispersal in were not part oi Gondwana, so it cannot be described the past. as strictly Gondwanan. Cichlids found in Madagascar and India are thought to be some of the most primitive species of the family (Fig. 2). Reinthal & Stiassny (1991) listed three of SALINITY TOLERANCE the nine endemic Madagascan cichlids as euryhaline. Implicit to interpreting the distribution oi cichlids Several of these species are not only tolerant of brack based on vicariant events is the assumption that cich- ish waters, but live in estuarine environments (Nor lids are obligate ireshwater fishes, unable to disperse man & Greenwood, 1975) and are occasionally found across marine barriers that separate the land masses in marine waters (Banarescu, 1990). Two species of the in which they now live. They therefore have been Indian/Sri Lankan genus Etroplus are salt-tolerant, assumed to have an origin predating the breakup oi living preferentially in brackish waters (Kiener & the continents on which they are found. Over fifty Mauge, 1966; Loiselle, 1994). This suggests that high years ago, Myers (1949: 318) pointed out that the salinity tolerance was a feature of the first cichlids, an Cichlidae are not limited by salinity and therefore hypothesis consistent with the fact that the perciform cannot be used as evidence of past land connections. families considered most closely related to the Cich- Myers (1949) was one of the first to separate fresh lidae (Stiassny, 1991) - the Embiotocidae, Labridae, water fishes into several divisions based on tolerance and Pomacentridae - are all marine groups. to salt waters. Freshwater fishes of the primary di Despite the evidence to the contrary, current lit vision are the only ones that are strictly intolerant erature shows