Chromosomal Homology and Evolution of Phyllostomatoid Bats

Abstract

Patton, 1. C., and R. 1. Baker (Department of Biological Sciences and The Museum, Texas Tech University, Lubbock, Texas 79409) 1978. Chromosomal homology and evolution of phyllostomatoid bats. Syst. Zool. 27:449-462.-Gand C-banding analyses were used to determine chromosome homology from representatives of bat families Mormoopidae, Noctilionidae and Phyllostomatidae, subfamily Phyllostomatinae. The karyotype of Macrotus waterhousii 2n = 46, F N = 60 is proposed as primitive for the Phyllostomatoidea. The major strategy involved in karyotypic evolution of taxa analyzed appears to have been reduction of the number of autosomal linkage groups by Robertsonian fusion from the 22 of Macrotus waterhousii to near 15 for the majority of taxa. Chromosome arms were found to be highly conserved. The X chromosomes of all taxa did not vary and were similar to the pattern thought to be characteristic of the primitive X of mammals. Two systematic groups appear recognizable within the Phyllostomatoidea above the family level (Phyllostomatidae in one group and the Noctilionidae and Mormoopidae in the other), whereas three systematic groups are discernible within the Phyllostomatinae. The three groups within the Phyllostomatinae include Macrotus waterhousii in the Macrotus-group, Tonatia minuta, Mimon crenulatum, Phyllostomus discolor and P. hastatus in the Tonatia-Mimon-Phyllostomus-group, and Micronycteris nicefori, M. brachyotis, and M, minuta in the Micronycteris-group. Tonatia bidens and Micronycteris megalotis were karyotypically so divergent that based solely on chromosomal data they could not be placed with any grouping. Examples are shown where extensive chromosomal evolution has been accompanied by little morphological evolution and where extensive morphological evolution has been accompanied by little chromosomal evolution. Such examples are the basis for questioning the hypothesis that chromosomal changes altering the position of regulator genes are a primary mechanism in the evolution of the large magnitude of morphological differentiation in the class Mammalia. [Phyllostomatoidea; Phyllostomatidae; Phyllostomatinae; Mormoopidae; Noctilionidae; G-bands; chromosome; phylogenetic relationships.] Evolutionary events and strategies inof the G-banding and C-banding patterns volving the karyotypes of vertebrates of bats of the genera Macrotus, Microhave been difficult to determine because nycteris, Tonatia, Mimon, Phyllostomus chromosome homology could only be in(subfamily Phyllostomatinae, family ferred. Data based on longitudinal differPhyllostomatidae), Pteronotus (family ential staining patterns for each chromoMormoopidae), and Noctilio (family Nocsome can be used as a test to reject or tilionidae). This particular combination accept proposed homologies, and thereof taxa offers the opportunity to examine by add to our understanding of mamma1)considerable chromosomal variation as lian evolutionary processes and phylogdiploid number varies from 16 to 46 and enies. G-banding and C-banding patterns fundamental number ranges from 20 to provide some of the same advantages to 68, which allows a determination of the cytogeneticists working with mammalian extent to which such chromosomal varichromosomes that the differentially ation has altered the G-banding patterns, banded chromosomes of Drosophila 2) representatives of phyllostomatids that have ~ r o v i d e d to evolutionists studying are believed most like the ancestral stock fruit flies. based on classical studies (see, Smith, This report is based on an examination 1976), and 3) representatives of all three families that are presently considered to Present address: Department of Zoology, Unihave been involved in early phyllostoversity of Georgia, Athens, Georgia 30602. matoid evolution (Smith, 1972, 1976). If