The taxonomic status of the blind snakes Leptotyphlops dulcis dulcis, L. dulcis dissectus and L. ... more The taxonomic status of the blind snakes Leptotyphlops dulcis dulcis, L. dulcis dissectus and L. dulcis myopicus was re-evaluated, based upon the study of 867 individuals from the United States and Mexico. The presence ofeither a single or a divided anterior supralabial was considered to be a conservative character; based on this character, the specimens were divided into two groups. Analysis of variance of total dorsal scales within these two groups, paired with Duncan's Multiple Range Test, suggests that these three taxa represent three full species. Within the group with a single anterior supralabial, L. dulcis comprises three races (L. dulcis dulcis, L. dulcis rubellum and an as-yet-unnamed race in eastern Oklahoma). Within the group with a divided anterior supralabial, L. dissectus is monotypic and L. myopicus consists of two races (L. myopicus myopicus and L. myopicus iversoni). Chihuahuan individuals previously classified as L. dulcis supraocularis were reassigned to L. d...
--The introduced house geckos, Hemidactylus turcicus and Cyrtopodion scabrum exist in sympatry in... more --The introduced house geckos, Hemidactylus turcicus and Cyrtopodion scabrum exist in sympatry in Galveston, Texas. The nightly perch choices of each species in captivity were recorded, first in species-segregated enclosures, then with species mixed. While segregated by species, H. turcicus occupied vertical walls more frequently than ground or rock perches. Cyrtopodion scabrum perched predominantly on rocks. While mixed in the enclosures, the proportion of individuals not visible increased independently for both species, while the proportion of both species occupying their respective preferred perches decreased. Perch heights did not differ between species, regardless of whether the species were segregated or mixed in the enclosures. The observed changes in use of space while in sympatry may be due to competitive interference between these two species, and may reflect the situation in Galveston, where C. scabrum appears to be gradually displacing H. turcicus in areas near the docks, where these two species previously existed in sympatry. l f erpetology, Vol. 30, No. 1, p. 46-51, 1996 i t 1996 Society for the Study of Amph bians and Reptiles i al Interference for Perch Sites in Two Species of Interspecific competition occurs when two or more species utilize the same limiting resources (Pianka, 1981). Species with overlapping re1 Present Address: Texas Parks and Wildlife Department, 4200 Smith School Road, Austin, Texas 78744, USA. specific competition occurs when two or species utilize the same limiting resources a, 1981). Species with overlapping res urce requirements may compete either by depletion of resources, or by competitive interf ence (Odum, 1971; Pianka, 1981; Schoener, 1982), such as aggressive dominance, mutual predation, or active inhibition, ultimately controlling free access to resources. Both types of competition may be considered negative interactions (Burkholder, 1952), in that both species 46 This content downloaded from 157.55.39.58 on Tue, 11 Oct 2016 04:31:24 UTC All use subject to http://about.jstor.org/terms PERCH CHOICE INTERFERENCE IN GECKOS are detrimentally affected. In consideration of positive-negative two-species population interactions, Odum (1971) emphasized that (1) "in the evolution and development of ecosystems, negative interactions tend to be minimized in favor of positive symbiosis that enhances the survival of the interacting species," and that (2) "recent or new associations are more likely to develop severe negative coactions than are older associations." Ortiz and Jenssen (1982) predicted that syntopic species of recent contact should exhibit particularly high intensities of interactions, because the coexisting species have had little time to undergo niche divergence. A number of studies have addressed the subject of interference competition (Case and Gilpin, 1974; Schoener, 1977; Salzburg, 1984; Jenssen et al., 1984; Bolger and Case, 1992; Klawinski et al., 1994). Salzburg (1984) provided experimental evidence that the lizards Anolis sagrei and A. cristatellus were competing by behavioral interference for habitat resources, and that access to those resources affected the fitness of the two species. Bolger and Case (1992), in a study of two species of asexual parthenogenic geckos (Lepidodactylus lugubris and Hemidactylus garnotii) and one sexual species (H. frenatus) found that behavioral interference by the latter, more recently introduced species, is at least partially responsible for an observed decline in the two asexual species on tropical Pacific islands. The present study investigates competitive behavioral interference for perch sites between two species of introduced house geckos, the Mediterranean gecko, Hemidactylus turcicus, and the more recently introduced roughtail gecko, Cyrtopodion scabrum. These species are currently coexisting in Galveston, Texas, in a recent association (Selcer and Bloom, 1984) that may not yet have reached equilibrium (Klawinski et al., 1994). Hemidactylus turcicus and C. scabrum occur syntopically in Galveston, Texas (Selcer and Bloom, 1984; Bloom et al., 1986), where they share the walls and windows of well-lighted stucco, wood, and brick buildings near the entrance to the Port of Galveston. Prior to 1983, C. scabrum was not known to occur in the United States, and the association between the two species in Galveston is probably of recent origin (Selcer and Bloom, 1984). Little has been reported about the life history and behavior of C. scabrum (Vaughan, 1991); however, this Old World house gecko's Middle East historical range overlaps that of H. turcicus (Conant and Collins, 1991). The two species are ecologically similar; H. turcicus and C. scabrum share similar body sizes and activity periods (Vaughan, 1991). Both species are known to perch upon walls or other vertical substrates while foraging (Conant and Collins, 1991; Klawinski et al., 1994). Both have been observed feeding on insects; spiders and flies comprise about…
relatively recent introduction of C. scabrum near the entrance of the Port has apparently led to ... more relatively recent introduction of C. scabrum near the entrance of the Port has apparently led to the disphcement of H. turcicus in that area. This has resulted in a distribution in which the two populations ' are largely allopatric except for a narrow band of sympatry at the periphery of each of their ranges. We examined stomach contents of both
... LARRY DAVID WILSON,1 R. KATHRYN VAUGHAN,2 AND JAMES R. DIXON2 ... proximate elevation 450 m, ... more ... LARRY DAVID WILSON,1 R. KATHRYN VAUGHAN,2 AND JAMES R. DIXON2 ... proximate elevation 450 m, collected 11 August 1968 by EC Welling M. Muste cannot be lo-cated on any maps available to us, but is likely to be on the road into the Central Chiapan De-pression ...
The taxonomic status of the blind snakes Leptotyphlops dulcis dulcis, L. dulcis dissectus and L. ... more The taxonomic status of the blind snakes Leptotyphlops dulcis dulcis, L. dulcis dissectus and L. dulcis myopicus was re-evaluated, based upon the study of 867 individuals from the United States and Mexico. The presence ofeither a single or a divided anterior supralabial was considered to be a conservative character; based on this character, the specimens were divided into two groups. Analysis of variance of total dorsal scales within these two groups, paired with Duncan's Multiple Range Test, suggests that these three taxa represent three full species. Within the group with a single anterior supralabial, L. dulcis comprises three races (L. dulcis dulcis, L. dulcis rubellum and an as-yet-unnamed race in eastern Oklahoma). Within the group with a divided anterior supralabial, L. dissectus is monotypic and L. myopicus consists of two races (L. myopicus myopicus and L. myopicus iversoni). Chihuahuan individuals previously classified as L. dulcis supraocularis were reassigned to L. d...
--The introduced house geckos, Hemidactylus turcicus and Cyrtopodion scabrum exist in sympatry in... more --The introduced house geckos, Hemidactylus turcicus and Cyrtopodion scabrum exist in sympatry in Galveston, Texas. The nightly perch choices of each species in captivity were recorded, first in species-segregated enclosures, then with species mixed. While segregated by species, H. turcicus occupied vertical walls more frequently than ground or rock perches. Cyrtopodion scabrum perched predominantly on rocks. While mixed in the enclosures, the proportion of individuals not visible increased independently for both species, while the proportion of both species occupying their respective preferred perches decreased. Perch heights did not differ between species, regardless of whether the species were segregated or mixed in the enclosures. The observed changes in use of space while in sympatry may be due to competitive interference between these two species, and may reflect the situation in Galveston, where C. scabrum appears to be gradually displacing H. turcicus in areas near the docks, where these two species previously existed in sympatry. l f erpetology, Vol. 30, No. 1, p. 46-51, 1996 i t 1996 Society for the Study of Amph bians and Reptiles i al Interference for Perch Sites in Two Species of Interspecific competition occurs when two or more species utilize the same limiting resources (Pianka, 1981). Species with overlapping re1 Present Address: Texas Parks and Wildlife Department, 4200 Smith School Road, Austin, Texas 78744, USA. specific competition occurs when two or species utilize the same limiting resources a, 1981). Species with overlapping res urce requirements may compete either by depletion of resources, or by competitive interf ence (Odum, 1971; Pianka, 1981; Schoener, 1982), such as aggressive dominance, mutual predation, or active inhibition, ultimately controlling free access to resources. Both types of competition may be considered negative interactions (Burkholder, 1952), in that both species 46 This content downloaded from 157.55.39.58 on Tue, 11 Oct 2016 04:31:24 UTC All use subject to http://about.jstor.org/terms PERCH CHOICE INTERFERENCE IN GECKOS are detrimentally affected. In consideration of positive-negative two-species population interactions, Odum (1971) emphasized that (1) "in the evolution and development of ecosystems, negative interactions tend to be minimized in favor of positive symbiosis that enhances the survival of the interacting species," and that (2) "recent or new associations are more likely to develop severe negative coactions than are older associations." Ortiz and Jenssen (1982) predicted that syntopic species of recent contact should exhibit particularly high intensities of interactions, because the coexisting species have had little time to undergo niche divergence. A number of studies have addressed the subject of interference competition (Case and Gilpin, 1974; Schoener, 1977; Salzburg, 1984; Jenssen et al., 1984; Bolger and Case, 1992; Klawinski et al., 1994). Salzburg (1984) provided experimental evidence that the lizards Anolis sagrei and A. cristatellus were competing by behavioral interference for habitat resources, and that access to those resources affected the fitness of the two species. Bolger and Case (1992), in a study of two species of asexual parthenogenic geckos (Lepidodactylus lugubris and Hemidactylus garnotii) and one sexual species (H. frenatus) found that behavioral interference by the latter, more recently introduced species, is at least partially responsible for an observed decline in the two asexual species on tropical Pacific islands. The present study investigates competitive behavioral interference for perch sites between two species of introduced house geckos, the Mediterranean gecko, Hemidactylus turcicus, and the more recently introduced roughtail gecko, Cyrtopodion scabrum. These species are currently coexisting in Galveston, Texas, in a recent association (Selcer and Bloom, 1984) that may not yet have reached equilibrium (Klawinski et al., 1994). Hemidactylus turcicus and C. scabrum occur syntopically in Galveston, Texas (Selcer and Bloom, 1984; Bloom et al., 1986), where they share the walls and windows of well-lighted stucco, wood, and brick buildings near the entrance to the Port of Galveston. Prior to 1983, C. scabrum was not known to occur in the United States, and the association between the two species in Galveston is probably of recent origin (Selcer and Bloom, 1984). Little has been reported about the life history and behavior of C. scabrum (Vaughan, 1991); however, this Old World house gecko's Middle East historical range overlaps that of H. turcicus (Conant and Collins, 1991). The two species are ecologically similar; H. turcicus and C. scabrum share similar body sizes and activity periods (Vaughan, 1991). Both species are known to perch upon walls or other vertical substrates while foraging (Conant and Collins, 1991; Klawinski et al., 1994). Both have been observed feeding on insects; spiders and flies comprise about…
relatively recent introduction of C. scabrum near the entrance of the Port has apparently led to ... more relatively recent introduction of C. scabrum near the entrance of the Port has apparently led to the disphcement of H. turcicus in that area. This has resulted in a distribution in which the two populations ' are largely allopatric except for a narrow band of sympatry at the periphery of each of their ranges. We examined stomach contents of both
... LARRY DAVID WILSON,1 R. KATHRYN VAUGHAN,2 AND JAMES R. DIXON2 ... proximate elevation 450 m, ... more ... LARRY DAVID WILSON,1 R. KATHRYN VAUGHAN,2 AND JAMES R. DIXON2 ... proximate elevation 450 m, collected 11 August 1968 by EC Welling M. Muste cannot be lo-cated on any maps available to us, but is likely to be on the road into the Central Chiapan De-pression ...
Uploads
Papers