Observatory Park, Geauga Co.
Research: Formation & ossification of limb elements in turtles
Though sequences of formation and ossification of bony elements have been described for many taxa, controversy surrounds the formation of limb elements turtles. Three hypotheses for patterns of formation of autopodial elements have been proposed, differing primarily in the origin of Distal Carpal/Tarsal 3, the digital arch, and Centrale 4 (Figure 1).
Patterns of formation and ossification of limb elements were described from embryos of the Red-Eared Slider, Trachemys scripta. Cleared and double-stained embryos provided the primary source of original data for this study (Figure 2),
and these patterns of were compared to similar data for representatives of four families of turtles (Cheloniidae, Chelydridae, Emydidae, and Trionychidae), and included the Common Snapping Turtle (Chelydra serpentina), Alligator Snapping Turtle (Macrochelys temminckii), Painted Turtle (Chrysemys picta), Black-knobbed Map Turtle (Graptemys nigrinoda), Spiny Softshell Tutle (Apalone spinifera), Loggerhead Sea Turtle (Caretta caretta), and the Green Seaturtle (Chelonia mydas). Hypotheses of limb formation were compared in the context of new and published data, and shed some light on how the elements of the hands and feet of turtles arise developmentally. Data from Trachemys scripta, Chrysemys picta, and Chelydra serpentina suggest that Distal Carpal 3 forms by branching from the ulnare, whereas data from Macrochelys temminckii and Chelonia mydas suggest that Distal Carpal 3 may branch from Distal Carpal 4. Data from Graptemys nigrinoda, Apalone spinifera, and Eretmochelys imbricata did not provide evidence for the origin of Distal Carpal 3. Centrale 4 was not observed to branch from the ulnare and apparently arises by de novo condensation. Distal Carpal 4 did not branch from Centrale 4 in any species. Until the developmental origin of Distal Carpal 3 and Centrale 4 are better understood, interspecific variation in the origin of these elements remains as a primary suspect in explaining much of the observed differences. Trends of ossification in the fore- and hind limb autopodium also are summarized were identified and it seems that though the proximal bones ossify in a proximal-to-distal pattern (similar to the pattern of formation), many of the distal elements (primarily the phalanges) ossify in a distal-to-proximal pattern (opposite of their patterns of formation). The previous observations demonstrate that formation and ossification of these elements are decoupled developmental events—this is a question that I would love to have a student working on in my lab. Finally, this study afforded an excellent opportunity to assess the homology of elements in pedal Digit V, and we suggest that the hooked proximal element of Digit V in the foot should be recognized as Distal Tarsal 5. In short, we suggest that the hooked proximal element of Digit V is a distal tarsal element, not a metatarsal. Though this may seem to be a trivial point, the hooked fifth “tarsal” has been considered one of the few synapomorphies of a clade known as the Sauropsida.
Patterns of formation and ossification of limb elements were described from embryos of the Red-Eared Slider, Trachemys scripta. Cleared and double-stained embryos provided the primary source of original data for this study (Figure 2),
and these patterns of were compared to similar data for representatives of four families of turtles (Cheloniidae, Chelydridae, Emydidae, and Trionychidae), and included the Common Snapping Turtle (Chelydra serpentina), Alligator Snapping Turtle (Macrochelys temminckii), Painted Turtle (Chrysemys picta), Black-knobbed Map Turtle (Graptemys nigrinoda), Spiny Softshell Tutle (Apalone spinifera), Loggerhead Sea Turtle (Caretta caretta), and the Green Seaturtle (Chelonia mydas). Hypotheses of limb formation were compared in the context of new and published data, and shed some light on how the elements of the hands and feet of turtles arise developmentally. Data from Trachemys scripta, Chrysemys picta, and Chelydra serpentina suggest that Distal Carpal 3 forms by branching from the ulnare, whereas data from Macrochelys temminckii and Chelonia mydas suggest that Distal Carpal 3 may branch from Distal Carpal 4. Data from Graptemys nigrinoda, Apalone spinifera, and Eretmochelys imbricata did not provide evidence for the origin of Distal Carpal 3. Centrale 4 was not observed to branch from the ulnare and apparently arises by de novo condensation. Distal Carpal 4 did not branch from Centrale 4 in any species. Until the developmental origin of Distal Carpal 3 and Centrale 4 are better understood, interspecific variation in the origin of these elements remains as a primary suspect in explaining much of the observed differences. Trends of ossification in the fore- and hind limb autopodium also are summarized were identified and it seems that though the proximal bones ossify in a proximal-to-distal pattern (similar to the pattern of formation), many of the distal elements (primarily the phalanges) ossify in a distal-to-proximal pattern (opposite of their patterns of formation). The previous observations demonstrate that formation and ossification of these elements are decoupled developmental events—this is a question that I would love to have a student working on in my lab. Finally, this study afforded an excellent opportunity to assess the homology of elements in pedal Digit V, and we suggest that the hooked proximal element of Digit V in the foot should be recognized as Distal Tarsal 5. In short, we suggest that the hooked proximal element of Digit V is a distal tarsal element, not a metatarsal. Though this may seem to be a trivial point, the hooked fifth “tarsal” has been considered one of the few synapomorphies of a clade known as the Sauropsida.
Research: Ecology of Turtles in Northeast Ohio
I have advised several Master's students on projects that cover aspects of the ecology of turtles in Norteast Ohio. These projects have focused on the Spotted Turtle (Clemmys guttata) and the Blanding's Turtle (Emydoidea blandingii). Though I am a morphologist, I have a passion for studying turtles, and will consider advising students on any project that involves these fine animals!
Genetic Algorith for Rule Set Prediction (GARP) is an ecological niche-modeling package that allows an investigator to correlate points of known locality data for a species with GIS variables (such as terrain aspect, maximum and minimum temperatures, precipitation, etc) to generate predictive models of suitable habitat for the species. We performed several GARP analyses to generate models of suitable habitat for the Spotted Turtle in North America and Ohio. The ultimate objective of this project was to assist the Geauga County Park District in identifying suitable habitat for this species on their land holdings. Both the national- and state-wide models identified broad ranges of over- and underprediction of suitable habitat, but the state-wide model appeared to perform much better on the scale of county-predictions.
[This figure shows the predicive model of suitable habitat for the Clemmys guttata in Ohio. Darkest purple indicates that 10 of 10 models predicted suitable habitat in this area; yellow dots represent known localities of this species]
Areas of potential habitat for the Spotted Turtle were identified and a list of suggestions was provided to GCPD to assist in the conservation of this species on their lands.
For additional information on this project, please contact me or Lara Roketentz, MSc.
The Blandings Turtle (Emydoidea blandingii) is a SINC species in Ohio. Though this species exhibits a relatively broad geographic range over much of North America, it is a habitat specialist that in reality can be found in very few patches of remaining habitat that are broadly separated from one another. Northeast Ohio has several remaining populations of this species, and relatively little is known about their populations in this state. Jim Spetz conducted an autecological study to describe and document the seasonal diet, movement, and reproduction of this species. Adult and hatchlings were trapped, tracked with radiotelemetry, and studied for over two years.
Results of this study are still being analyzed, but it seems that this species is an opportunist in terms of diet, and feeds on a variety of seasonally-available invertebrates, ranging from crayfish, insects, and molluscs (native and introduced). Females seem to exhibit some fidelity to nesting sites, and nest success and juvenile recruitment into the population is extremely low.
Genetic Algorith for Rule Set Prediction (GARP) is an ecological niche-modeling package that allows an investigator to correlate points of known locality data for a species with GIS variables (such as terrain aspect, maximum and minimum temperatures, precipitation, etc) to generate predictive models of suitable habitat for the species. We performed several GARP analyses to generate models of suitable habitat for the Spotted Turtle in North America and Ohio. The ultimate objective of this project was to assist the Geauga County Park District in identifying suitable habitat for this species on their land holdings. Both the national- and state-wide models identified broad ranges of over- and underprediction of suitable habitat, but the state-wide model appeared to perform much better on the scale of county-predictions.
[This figure shows the predicive model of suitable habitat for the Clemmys guttata in Ohio. Darkest purple indicates that 10 of 10 models predicted suitable habitat in this area; yellow dots represent known localities of this species]
Areas of potential habitat for the Spotted Turtle were identified and a list of suggestions was provided to GCPD to assist in the conservation of this species on their lands.
For additional information on this project, please contact me or Lara Roketentz, MSc.
The Blandings Turtle (Emydoidea blandingii) is a SINC species in Ohio. Though this species exhibits a relatively broad geographic range over much of North America, it is a habitat specialist that in reality can be found in very few patches of remaining habitat that are broadly separated from one another. Northeast Ohio has several remaining populations of this species, and relatively little is known about their populations in this state. Jim Spetz conducted an autecological study to describe and document the seasonal diet, movement, and reproduction of this species. Adult and hatchlings were trapped, tracked with radiotelemetry, and studied for over two years.
Results of this study are still being analyzed, but it seems that this species is an opportunist in terms of diet, and feeds on a variety of seasonally-available invertebrates, ranging from crayfish, insects, and molluscs (native and introduced). Females seem to exhibit some fidelity to nesting sites, and nest success and juvenile recruitment into the population is extremely low.
