) 1982. Cladistical analysis of G-banded chromosomes i n nectar feeding bats (Glossophaginae: Phyllostomidae). Syst. Zool.,.-Differentially stained chromosomes, when analyzed in a cladistic framework, provide a systematic hypothesis for ten glossophagine genera. Two separate groups are recognized on the basis of chromosomal data; a chromosomally conservative or plesiomorphic group consisting of Glossophaga, Monophyllus, Leptonycteris, and the brachyphyllines, and a relatively rapidly evolving derived group consisting o f d n o u r a , Lonchophylla, Lionycteris, Choeroniscus, Choeronycteris, Hylonycteris, and Musonycteris. Among the six genera characterized as slowly evolving, only a single rearrangement has been identified, whereas, among the seven genera characierized as rapidly evolving over 100 chromosomal rearrangements are required to explain the observed variation. Such a contrast in rate and type of chromosomal evolution is difficult to explain in terms of most currently accepted theories,,of chromosomal evolution and the pattern of change is most like "karyotypic megaevolution. Within the derived group, cladistic relationships are resolved to the generic level. Variation in the magnitude of evolution at the morphological and chromosomal levels is such that chromosomal data are useful for the resolution of relationships among genera, whereas, morphological data are more informative at the subfamilial level. A combination of the two data sets is compatible with the hypothesis that the Glossophaginae is monophyletic and provides a better understanding of the nature of evolution within this subfamily.
Homologous segments identified by G-banding sequences of chromosomes of Peromyscus boylii, Neotoma micropus, Oryzomys capito, (Family Cricetidae) Rattus norvegicus, Melomys burtonL and Apodemus sylvaticus (Family Muridae) were used to hypothesize a chromosomal condition for the cricetid ancestor. A critical assumption in proposing the primitive G-banding sequences for a given chromosome is that if the outgroup and ingroup taxa have a specific sequence, then the ancestor of the ingroup taxa also had that same sequence. Using this methadology, (chromosome numbers refer to proposed homology to the standardized karyotype for Peromyscus)
Differential staining (G- and C-banding) is used to assess magnitude of chromosomal variation in eight species of African megachiropterans. These data are compared with those suggested by standard karyotypic studies, and it is concluded that in this example standard methods underestimate chromosomal variation by a factor greater than 4.5. The implication of these data is that models constructed from patterns of chromosomal evolution in standard karyotypes need to be evaluated in light of in-depth studies based on G- and C-bands.
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