Ecology of North American Freshwater Fishes. Stephen T. Ross Ph. D.
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from eastern North America and western Europe (Figure 2.5E). As a group, the Cyprinidae likely originated in the Oriental region where all major cyprinid groups are represented (Cavender 1991).
From an ecological standpoint, the speciose cyprinids are relatively recent arrivals to North America and were thus a new element incorporated into fish assemblages already composed of older groups such as salmonids, esocids, ictalurids, and others (cf. Figure 2.3). The rapid radiation of minnows was perhaps related to the rise of many insect families such as the dipterans (Cavender 1991).
GOODEIDAE (45 SPECIES) The distribution of the goodeids includes the western Great Basin of the United States (subfamily Empetrichthyinae) and the Mexican plateau (subfamily Goodeinae) (Berra 2001; Webb et al. 2004). The oldest fossils are Miocene—the subfamily Goodeinae is represented by the extinct genus Tapatia from deposits in the state of Jalisco, Mexico (Cavender 1986), and the subfamily Empetrichthyinae by material of the extant genus Empetrichthys from deposits in Southern California (Webb et al. 2004). A molecular-based phylogeny indicates that the family originated 23 mya, which corresponds well to the Miocene fossils. The two subfamilies diverged between 11.5 and 16.8 mya (Doadrio and Dominguez 2004; Webb et al. 2004).
The family is thought to have originated in North America (Gilbert 1976; Burr and Mayden 1992). Increasing aridity during the Tertiary may have fragmented the once continuous range of the family, resulting in the divergence of the two subfamilies (Parenti 1981; Webb et al. 2004).
POECILIIDAE (69 SPECIES) The livebearers are primarily a Neotropical group with most of the diversity centered in Mexico, Central America, South America, and the West Indies, and with relatively few species in temperate North America (Parenti 1981; Rauchenberger 1988). There are no known fossils of this group in North America and no pre-Quaternary fossils known at all (Hedges 1996). This led Matthews (1998) to suggest a recent (< 1 mya) North American age for the family. However, recent molecular phylogenetic studies of Poeciliopsis, a large genus within the family that occurs on the central Mexican Plateau, indicate that divergence within this genus occurred 6–18 mya (Mateos et al. 2002). As a consequence, the age of the family in North America must be at least Miocene. In further support of this, both morphological (Parenti 1981) and molecular phylogenies (Meyer and Lydeard 1993) show that the clade containing the Poeciliidae and the clade containing the Goodeidae are sister groups (i.e., derived from a common ancestor). Given that a molecular phylogeny (Webb et al. 2004) places the origin of the Goodeidae in the Miocene (ca. 23 mya), a similar age should apply to the Poeciliidae. North American poeciliids are most likely derived from Central American ancestors (Gilbert 1976; Burr and Mayden 1992; Lydeard et al. 1995).
CICHLIDAE (16 SPECIES) This large family has a broad Neotropical distribution occurring in Mexico, Central and South America, and the West Indies, with one species, the Rio Grande Cichlid (Cichlasoma cyanoguttatum), even reaching into the United States. Cichlids are poorly represented in the North American fossil record. In the Paleotropics, cichlids occur in Africa, Madagascar, and parts of southern Asia (India, Sri Lanka, Syria, and Iran) (Murray 2001a). There is a Miocene fossil of the modern genus Cichlasoma that was found in Haiti (Cavender 1986; Hedges 1996; Murray 2001a), and the oldest known cichlid fossil was found in an African deposit and dates from the middle Eocene (Murray 2001b). One view is that the separation between African and South American cichlids may postdate the formation of the Atlantic Ocean and that South American cichlids were derived from marine dispersal of cichlids from Africa, with molecular phylogeny suggesting a divergence time of 58–41 mya (Vences et al. 2001). However, a more recent review supports a vicariance hypothesis and thus requires an older age for divergence of New and Old World cichlids (Chakrabarty 2004).
The family as a whole is thought to have an early Tertiary origin, and movement from South America to Central America perhaps occurred in the late Tertiary (ca. < 20 mya) (Myers 1966; Murray 2001a). Consequently, the origin of cichlids in North America (primarily Mexico) could have occurred as early as the middle Miocene (ca. 12–15 mya).
PERCIDAE (186 SPECIES) Percids are the second most speciose family of North American freshwater fishes. The family occurs in Europe, northern Asia, and eastern North America (Collette and Banarescu 1977; Berra 2001) and seems to represent a Laurasian clade (Wiley 1992; Carney and Dick 2001). The family likely originated in the early Tertiary (Paleocene; ca. 65 mya) when land connections existed between eastern North America and Europe (Figure 2.5D) (Wiley 1992; Carney and Dick 2001). However, fossil remains of percids are only dated to the Miocene (26 mya) (Carney and Dick 2001), and the earliest North American percid fossils are from Pleistocene deposits (ca. 2 mya) in areas now located in Texas and Oklahoma (genus Perca) and South Dakota (Percina and Etheostoma) (Cavender 1986). Given the currently available information, it is not possible to distinguish between a dispersal hypothesis, with percids evolving in Europe and then dispersing to North America via the North Atlantic connection, or a vicariance hypothesis, with percids evolving in Laurasia and then being separated by the formation of the North Atlantic Ocean (Carney and Dick 2001). However, given that fossils likely underestimate ages of percids, I have shown the Laurasian origin in Figure 2.4.
The first occurrence of darters in North America is likely far earlier than indicated by the Pleistocene fossils. A molecular phylogeny of the darter family (Percidae), with the rate of genetic change (i.e., the molecular clock) based on a fossil-calibrated phylogeny of centrarchids, shows the separation of darters from nondarter percids occurring 19.8 mya (Carlson et al. 2009). The 18.5 mya age of the most recent common ancestor to the darter genus Nothonotus provides further evidence of at least a Miocene origin of darters (Near and Keck 2005). Finally, a recent molecular phylogeny of logperches (genus Percina) showed that divergence began in the Pliocene (ca. 3–5 mya), although most speciation events in this group did occur within the Pleistocene (Near and Benard 2004).
FUNDULIDAE (34 SPECIES) Members of this group occur in North and Central America as well as Cuba; in North America all but two species occur east of the continental divide (Berra 2001). The oldest fossil evidence in North America dates from the middle Miocene (ca. 16 mya) and perhaps is of the modern genus Plancterus (Cavender 1986). North American fundulids apparently are derived from Central American ancestors (Briggs 1986, 1987) and, in support, phylogenies based on morphological and molecular data are consistent in placing the Central American family Profundulidae as basal to the Fundulidae (Parenti 1981; Wiley 1986; Bernardi 1997).
CYPRINODONTIDAE (35 SPECIES) Cyprinodontid fishes include both marine/estuarine and freshwater forms that are found primarily along coastal regions (with some notable exceptions) in North, Central, and South America, and the Mediterranean region including North Africa (Parenti 1981; Berra 2001). One view is that the distribution of the cyprinodontiform fishes suggests, in part, a reduced Pangean pattern (Figure 2.2), with members of the group absent from Australia and Antarctica (Parenti 1981). Correspondingly, the order Cyprinodontiformes likely existed at least from the late Triassic before the breakup of Pangea (Figure 2.5A), and New World cyprinodontids perhaps date from the early Tertiary (Parenti 1981). An alternative view places the origin of the group at a later time in the early Cretaceous when Africa and South America were only divided by a narrow saltwater passage (Figure 2.5B, C) (Briggs 1986).
The relatively great age of New World cyprinodontids is also supported by molecular studies of the amount of divergence between New and Old World species (Echelle and Echelle 1993). The North American cyprinodontids are likely derived from a marine ancestor (Gilbert 1976; Parker and Kornfield 1995). However, the hypothesis that lineages of inland species of Cyprinodon in North America have been derived independently from the widely distributed coastal species, although initially supported by a reduced data set of western species in the Cyprinodon variegatus complex (Echelle and Echelle 1992), has not been substantiated by a more complete study of the family (Echelle et al. 2005).
In spite of the suggested age of the order and of New World Cyprinodontidae, the fossil record for the family in North America is meager. The only known North American fossil, of the extinct species Cyprinodon breviradius, is from late Miocene/early Pliocene deposits near Death Valley, California (7–9 mya) (Miller 1981; Cavender 1986). However, there are recent phylogenies, based on water-soluble proteins (allozymes) and mitochondrial DNA, that provide times of divergence for North American genera and species (Echelle and Echelle 1992; Echelle et al. 2005). Molecular