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The status of short-horned lizards, Phrynosoma douglasi and P. hemandezi, in Canada
Abstract
Short-horned Lizards reach their northern distribution limits in British Columbia, Alberta, and Saskatchewan. Two specimens of the Pygmy Short-horned Lizard (P. douglasi) were reported in 1898 from the vicinity of Osoyoos, British Columbia; there have been no validated sightings since. It was probably found on the sandy lacustrine terraces lining the bottom of the Okanagan Valley in the vicinity of Osoyoos Lake, but intensive searches of this area in August 1991 were negative. The Short-horned Lizard (P. hernandezi) has an interrupted distribution in southeastern Alberta and southwestern Saskatchewan. The vegetation within its range in these provinces is mixed grass prairie within the dry steppe climatic region. Populations in these provinces are confined to south-facing slopes, grassland-badlands ecotones, and Bearpaw shale outcrops. The distribution appears to be relictual. Phrynosoma douglasi is apparently extirpated in British Columbia and Phrynosoma hernandezi is vulnerable in Alberta and Saskatchewan.
... Research on short-horned lizard habitat relationships has been limited (Pianka and Parker 1975;Powell and Russell 1998a, 1998b, James 2004, partly because of their cryptic nature. Short-horned lizard occur- FIG. ...
... Within the WBEA, short-horned lizards were more likely to occur in low productivity areas, relatively flat habitats, and sites with decreased topographic moisture. These habitat associations fit with the life history and habitat associations of this desert dwelling species (Pianka and Parker 1975, Powell and Russell 1998b, Powell et al. 1998, Sherbrooke 2003). Short-horned lizards were found in all habitat types but riparian near Vernal, Utah (Grant 1986) and typically inhabited upland habitat in areas bisected by riparian vegetation, swales and other topographically moist areas (Pianka and Parker 1975). ...
... Scientific and Common Names of 17 Horned Lizards, genus Phrynosoma, with notations of countries of occurrence (United States, US; Mexico, MX, Canada, CAN). There are 9 species in the United States, 16 in Mexico, and 1 + 1 (?) in Canada (with P. douglasii apparently extirpated in Canada;Powell and Russell 1998). Those not in bold font are suggested alternatives. ...
Scientific and common names of horned lizards, Phrynosoma.
... Scientific and Common Names of 17 Horned Lizards, genus Phrynosoma, with notations of countries of occurrence (United States, US; Mexico, MX, Canada, CAN). There are 9 species in the United States, 16 in Mexico, and 1 + 1 (?) in Canada (with P. douglasii apparently extirpated in Canada; Powell and Russell 1998). Those not in bold font are suggested alternatives. ...
Common and scientific names of Phrynosoma lizards.
Most temperate-climate lizards become inactive during the winter months of each year. As temperatures drop, they must find appropriate overwintering microhabitats to avoid lethal surface temperatures and/or thermoregulate. The environmental variables that characterize such microhabitats and the cues that lizards utilize to assess them are a critical but understudied component of their natural history. While many studies of overwintering site selection focus on temperature, other factors constituting microhabitats (e.g., surface structures, substrate) may play a role in site selection. We used the Jacky Dragon (Amphibolurus muricatus), an Australian agamid lizard, to test for preference of using various cover types (leaf litter, open sand, sticks, rocks) for overwintering as well as the consequences of cover type selection. Jacky Dragons preferred overwintering beneath leaves compared to other structures, and this choice was associated with growth during winter, but not with survival. Our study highlights the potential importance of cover structures in overwintering site selection, suggests that midwinter activity may be common in Jacky Dragons, and calls for further study of the winter ecology of temperate-climate lizard species. © 2017 by the American Society of Ichthyologists and Herpetologists.
Short-horned lizards (Phrynosoma douglasii species complex) occur throughout the inter-montane West and Great Plains of western North America. The comparative morphology and color pattern variation of short-horned lizards was studied in 3,174 specimens. Multivariate analyses of 20 morphological and color-pattern characters were applied to 977 specimens, and univariate statistics were summarized for 52 samples totaling 1,134 specimens. The results of the morphological data analyses support the recognition of P. douglasii (Bell 1828) as a distinct species, and the resurrection of P. brevirostris Girard 1858a and P. ornatissimum Girard 1858a as species distinct from P. hernandesi Girard 1858a. Two new species allied to P. brevirostris are described: P. bauri sp. nov. from the eastern plains of Colorado and northeastern New Mexico, southeastern Wyoming and southwestern Nebraska south of the North Platte River, and P. diminutum sp. nov. endemic to the San Luis Valley of southern Colorado and northern New Mexico. The Mexican taxon brachycercum Smith 1942 is reassigned as a subspecies of P. ornatissimum, based on non-discrete character differences and overall morphometric similarity. The ranges of P. hernandesi and P. ornatissimum broadly overlap in central New Mexico, the former taxon occupying the coniferous forests of disjunct mountain ranges, the latter occuring in the surrounding desert grasslands. Principal components analysis has revealed morphological evidence of hybridization where the two taxa meet, generally within ecotones between montane forest associations and grasslands. Principal components analysis has also revealed a high level of morphological variability in populations occurring in the Colorado Plateau region of northeastern Arizona, northwestern New Mexico, extreme southwestern Colorado and adjacent Utah. The evidence suggests that these populations arose through past hybridization between the two species. The taxon ornatum Girard 1858b, although sharing several traits with P. brevirostris, is morphologically close to P. hernandesi. It is regarded as a stabilized population of hybrid origin, but treated taxonomically as a subspecies of P. hernandesi. The taxonomic arrangement in this study, with the exception of P. douglasii, is largely discordant with the proposed taxonomy from a previously published study based on mitochondrial DNA sequence data.
We assigned national conservation priority ranks to the 93 native and introduced Canadian amphibian and reptile species using the International Union for the Conservation for Nature and Natural Resources (lUCN) [=World Conservation Union] criteria and The Association for Biodiversity Information (ABI) criteria independently. We used these results, along vv'ith national designations previously assigned to a number of these species by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), to compare the three ranking systems at the national scale. We also used existing lUCN and ABI ranks to compare these two systems at the global scale. At the global scale, considerable variability exists, and it is not possible to determine the rank under one system by determining the rank under the other — the only way to find out for certain is to evaluate the species against the criteria. At the national scale, there is not good correspondence between the COSEWIC system and the lUCN system. However, there is excellent correspondence between the COSEWIC and ABI systems: all 26 species with concern status assigned by COSEWIC (Endangered, Threatened, or Vulnerable) were ranked N1-N3, NX or NH using the ABI system. All five N4 and N5 species were ranked Not At Risk by COSEWIC. The ABI system appears to be more sensitive than the lUCN system at the lower risk levels, while the lUCN system focusses on the levels of higher risk. Species highly ranked using the ABI system (NX, NH, Nl, or N2) always had a rank of concern using the lUCN system (RE, CR, EN, VU, or NT), whereas species ranked low in the ABI system (N4 or N5) were always ranked Least Concern (LC) using the lUCN system. We believe that this strong relationship will hold for other taxonomic groups. Both the lUCN and ABI ranking systems have merits, and it might be useful to evaluate species using both systems independently. We suggest combining the two ranks into a new national rank, and we present a simple way of doing this. This process should lead to a stronger justification for the status ultimately given. In the longer term, a single system incorporating the benefits of the ABI and lUCN systems is desirable. However, one drawback to making major changes to either system is that species already evaluated will have to be re-evaluated depending on the extent of the changes.
The northern edge of the range of the Greater Short-horned Lizard (Phrynosoma hernandesi Girard, 1858) occurs in western Canada, where the species has “endangered” status and exhibits a patchy distribution. Phylogenetic inference and genetic analyses were employed to investigate the genetic structure of P. hernandesi throughout its Canadian range. One nuclear and two mitochondrial DNA genes were sequenced from 94 lizard tail tips. Overall, sequences from lizards from both Alberta and Saskatchewan displayed very little variability, and the consistent clustering of all the P. hernandesi mitochondrial and nuclear DNA sequences from Canada in both phylogenetic and population genetic analyses is consistent with the lizards from all sampled localities having originated from a single glacial refugium, and with being, until recently (or currently) interconnected genetically. The genetic data obtained so far furnish no information useful for interpreting the species’ present-day patchy distribution patterns or for formulating conservation strategies.
The Alberta populations are less strongly myrmecophagous than the average for the species, when the diet is broken down by prey item counts. Breakdown of the diet by prey dry weight shows that ants, nonsilphid Coleoptera, and Orthoptera are the major components of the diet. The range of prey sizes taken is large, but the species concentrates on a small range of prey sizes, from 2.1-6.0 mm in length. Arthropod abundances are significantly different between all 3 study sites, and there is always a significant difference in distribution between the pooled pitfall samples and the pooled gut samples of any one study site. Data suggest some dietary flexibility. The size range of prey items taken by the large lizards includes and slightly exceeds the size range of prey items taken by medium-sized lizards, and there is a significant positive correlation of average prey size with lizard snout - vent length. There are significant differences in the prey sizes, prey dry weights, and prey item counts between large and medium-sized lizards, indicating intersexual dietary partitioning. -from Authors ants Coleoptera Orthoptera.
Three age classes were evident in both species: young-of-the-year, juveniles, and adults. In both species, adult females were significantly larger than adult males, due to continued growth of 1st year adult females and cessation of growth in similarly sized males. Both species maintained densities of c14 individuals ha⁻¹. Survival of adults over winter was high in adults of both species. Survival of juvenile S. graciosus was similar to that of adults; that of young-of-the-year and juvenile P. douglassi was lower than that of adults, possibly related to greater reproductive effort of this species. Both species exhibit the long-lived iteroparous reproductive strategy. That females were larger than males in both species may be related to this reproductive strategy. -from Authors
Phrynosoma douglassi brevirostre has a median body temperature (Tb) of 32.9oC in SE Alberta, with a sharply peaked and negatively skewed Tb frequency. The range of the Tb frequency distribution in daylight hours during the active season (activity temperature range) is wide (20.0oC). The realized thermal niche is approx 7oC wide, centred loosely on the median Tb. The populations examined are active over a wide range of ambient temperatures. With regard to substrate temperature and air temperature at 10cm, the populations are intermediate between thermoconformity and thermal independence, but with regard to air temperature at 1m they display more thermal independence. Habitat use is most varied on sunny days. Shuttling is an important thermoregulatory strategy. There is a significant difference in median Tb between small and large lizards, but not between either of these size groups and medium-sized lizards. Small lizards utilize significantly warmer substrates than the other 2 size groups. Large lizards are more closely coupled to substrate temperature, and less closely coupled to air temperature, than small lizards. Medium-sized lizards have a wider realized thermal niche than the other 2 size groups and are intermediate in their thermal relations relative to the other 2 size groups. -Authors
One climax community of Fescue Prairie and five climax and edaphic climax communities of Mixed Prairie are characterized on the basis of studies in ninety-six relatively undisturbed sites over an 18-year period in the glaciated, Canadian Great Plains. This classification represents modifications from one proposed a decade ago on the basis of response of communities to more favourable growing conditions from 1950 to 1956. The relative dominance of species is judged on the basis of calculated foliage yield. The communities are: A. Festuca scabrella Association of black soil. B. Mixed Prairie 1. Stipa-Agropyron Faciation of medium-textured soils in the dark-brown and moist portion of the brown soil zones. 2. Stipa-Bouteloua-Agropyron Faciation of medium-textured soils in the arid portion of the brown soil zone. 3. Stipa-Bouteloua Faciation, an edaphic community of well stabilized sandy soils. 4. Bouteloua-Agropyron Faciation, an edaphic climax in the more arid areas where Cretaceous shale has modified the drift. 5. Agropyron-Koeleria Faciation, an edaphic climax on fine-textured lacustrine soils. The nature of these grassland communities is similar to those which have been described in adjacent areas of the United States south of the glacial boundary. The more xeric types of Canada extend southward, while the mesic types do not. Primary and secondary plant successions towards the climax and edaphic climax communities are described.
The eastern short-horned lizard, Phrynosoma douglassii brevirostre, reaches the northern limit of its geographical range in southeastern Alberta. Populations in this area are found in the drainage basins of the South Saskatchewan River, Pakowki Lake and Milk River. The vegetation of the area is typical short-grass prairie. Populations are confined to south-facing slopes, badland-grassland ecotones and Bearpaw shale outcrops. The range is within the dry steppe climatic region, having short, hot summers and high insolation. The active season of the lizards is from late April-early May until early September. Geologic and vegetative factors appear to account for the presence of P. d. brevirostre at high latitudes.
1.1. Phrynosoma m'calli is considered an “obligatory hibernator”, since it could not be maintained in an active condition through the winter under laboratory conditions used successfully to keep other local lizards active.2.2. There was no evidence of dormancy or reduced metabolism due to reduced temperature (to 15°C) in summer.3.3. Oxygen consumption was essentially the same in field lizards and in captives held either in outdoor cages or at 15°C in summer, when measured at 15°C or 35°C. However, consumption was significantly higher in both groups of captives than in field animals when measured at 25°C.4.4. When measured at 35°C, lizards permitted to hibernate at 25°C or below during winter possessed a significantly reduced metabolic rate, compared with field animals. Evidence is presented to indicate a reduced metabolism at this temperature in winter may be a beneficial adaptation.5.5. Lizards became dormant when held continuously at 35°C in winter, but they maintained metabolic rates comparable to field animals.6.6. Lizards exposed to experimental photoperiods before 21 June did not become dormant before the experiment terminated on 21 December, despite the length of photoperiods used (6 hr/day and 15 hr/day). However, both groups showed a significantly reduced metabolic rate when measured at 35°C, comparable to animals hibernating at 25°C or below.7.7. Thus, dormancy and metabolic rate of hibernating P. m'calli apparently are controlled independently. Present evidence suggests winter dormancy is controlled by reduced photoperiod, and a lowered metabolic rate by reduced temperature. In both cases, such changes in the environmental conditions produce these physiological modifications associated with hibernation only during the proper season.8.8. Anorexia occurred at approximately the same time each year under all régimes of light and temperature that were investigated. At present, the stimulus to produce anorexia in P. m'calli is unknown.9.9. Lizards experimentally removed from the dormant condition in mid-December began conducting their usual spring activities by early January, approximately 3 months earlier than normal.10.10. Spring emergence is not entirely temperature controlled, since emergence occurred in lizards held continuously at 15°C. One of these animals had been in total darkness since late October.11.11. The term brumation is proposed to indicate winter dormancy in ectothermic vertebrates that demonstrate physiological changes which are independent of body temperature.