Fission in the Evolution of a Lizard Karyotype

Webster, T. Preston; Hall, William P.; Williams, Ernest E.

doi:10.1126/science.177.4049.611

Cited by 40 publications

(23 citation statements)

References 13 publications

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“…In these anoles, chromosome numbers between species range from 36-48 (Webster et al, 1972;Williams & Webster, 1974). Within Anolis monticola, the most derived form, a lesser range of polymorphism is observed (46 to 48).…”

Section: Discussionmentioning

confidence: 99%

Complex chromosomal variation in natural populations of the Jamaican lizard Anolis grahami

Blake

1986

Genetica

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Studies of chromosomal variation were undertaken in Anolis grahamk Multiple fission events and extensive variation involving heterochromatic sequences were observed. Distribution of the chromosomal variants did not coincide with subspecies borders. Chromosome numbers ranging from 30 to 37 were observed in both morphological subspecies; different rearrangements were involved in each. C-banding studies revealed cryptic variation in a large macrochromosome of some populations of A. g. grahamL and the presence of an additional heterochromatic arm in A. g. aquarum. Patterns of distribution of various forms, including widespread polymorphism, suggest significant dispersal of Anolis grahami, and little selection against chromosomal heterozygotes.

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Section: Discussionmentioning

confidence: 99%

Complex chromosomal variation in natural populations of the Jamaican lizard Anolis grahami

Blake

1986

Genetica

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“…This has led some to postulate allacrocentric primitive karyotypes even in cases where a predominately metacentric karyotype may be more parsimonious. Our lack of understanding of the exact mechanism of fission rearrangement should not lead us to believe that fissions do not occur (McBee et al, 1987), since it has long been established that many organisms including S. grammicus are able to generate acrocentric from biarmed chromosomes (John & Freeman, 1975;Paull et al, 1976;Southern, 1969;Webster et al, 1972;Whitehouse et al, 1984). We use the term 'fission' to refer to any rearrangement which produces two acrocentric chromsomes from one metacentric, regardless of the specific mechanism involved.…”

Section: Chromosomal Mutation Ratesmentioning

confidence: 99%

Evolution of Sceloporus grammicus complex (Sauria: Iguanidae) in central Mexico II. Studies on rates of nondisjunction and the occurrence of spontaneous chromosomal mutations

Porter

Sites

1987

Genetica

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The iguanid lizard Sceloporus grammicus has a high level of karyotypic variability, and has often been cited as an example of chromosomal speciation. We examined a total of 2036 secondary spermatocytes from 30 S. grammicus males, and found that 16 of the 30 individuals (including a single lizard collected from a hybrid zone between two chromosome races) produced completely balanced spermatocytes. Fourteen of the 30 lizards (including both chromosomal heterozygotes and homozygotes) had relatively low (0.6% to 7.1°70) levels of aneuploidy. Heterozygotes had a 1.1°70 increase over homozygotes in the number of aneuploid spermatocytes observed. The frequency of aneuploidy in S. grammicus may not be high enough to cause chromosomal speciation by any of the mechanisms that have been proposed for this complex. Most individuals showed balanced segregation of the autosomal trivalents, but nearly half of the lizards had a significant excess of spermatocytes with the X 1 and X 2 rather than the Y sex chromosomes. Five lizards had spermatocytes which had fission mutations not found in the somatic cells. As many as 5.9o70 of the spermatocytes in one individual had chromosomal mutations. This chromosomal mutation rate has important implications for chromosomal evolution in S. grammicus.

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“…The 2 grass-herb species, semilineatus and koopmani, apparently derived from divergent species stocks (Williams 1961, Webster et al 1972), show striking convergence in body size, color pattern, perch diameter use (Table 1) and 3) and height range (Fig. 4).…”

Section: Ecomorphs and Community Structurementioning

confidence: 99%

Habitat Constraints on the Behavior, Morphology, and Community Structure of Anolis Lizards

Moermond¹

1979

Ecology

159

127

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. A conceptual model of Anolis-habitat interactions is proposed to explain the existence of the series of Anolis ecomorphs in the Greater Antilles. The use of perches, type of movement among perches, and the morphology of 7 species of Anolis lizards from 2 sites in Haiti were compared. Movements of anoles through the habitat are assumed to be constrained more by the dispersion of perches rather than the characters of the perches themselves. The habitat is viewed as consisting of three-dimensional structural matrices of perches differing primarily in the diameters, lengths, and distances apart of the perches. Species occupying divergent types of perch matrices are shown to differ in: (I) the rapidity of moves on surfaces, (2) the frequency of jumps between surfaces, and (3) the distances jumped between surfaces. These species can be separated into jumpers, runners, and crawlers based on movement type and various body and limb proportions.The horizontal and vertical distribution of each species within a habitat gradient coincides with the distribution of the particular perch matrices to which the species is adapted. The varying degree of restriction imposed by perch matrices may have important evolutionary implications, particularly for the dispersion of size classes within the habitat and hence for species' exploitation strategies. Applications of this approach to arboreal primates and foliage-gleaning birds are suggested.

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Fission in the Evolution of a Lizard Karyotype

Cited by 40 publications

References 13 publications

Complex chromosomal variation in natural populations of the Jamaican lizard Anolis grahami

Complex chromosomal variation in natural populations of the Jamaican lizard Anolis grahami

Evolution of Sceloporus grammicus complex (Sauria: Iguanidae) in central Mexico II. Studies on rates of nondisjunction and the occurrence of spontaneous chromosomal mutations

Habitat Constraints on the Behavior, Morphology, and Community Structure of Anolis Lizards

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