Temporal Variation in Growth Rate and Age at Maturity of Male Painted Turtles, Chrysemys picta

1993 ◽  
Vol 130 (2) ◽  
pp. 314 ◽  
Author(s):  
Nat B. Frazer ◽  
Judith L. Greene ◽  
J. Whitfield Gibbons
1979 ◽  
Vol 57 (5) ◽  
pp. 1046-1051 ◽  
Author(s):  
Shannon F. Timmers ◽  
Paul D. Lewis Jr.

One new monogenean is described and 11 other helminths are reported from painted turtles from eastern Manitoba. Polystomoides pauli sp.n. from the host's oral mucosa most closely resembles P. coronatum (Leidy) and P. oris Paul. It differs from the former in having more and larger genital coronet spines, and possession of anterior cecal diverticula, and from the latter in size, larger number of genital coronet spines, and possession of great hooks with entire, not bifid, roots. Price's emendation of P. coronatum to include five species he held to be its synonyms is rejected; and the five species, P. opacum Stunkard, P. megacotyle Stunkard, P. microcotyle Stunkard, P. albicollis MacCallum, and P. digitatum MacCallum are designated species inquirendae. Polystomoides coronatum is restricted to the redescription given for it by Stunkard. The trematodes Crepidostomum sp., Eustomos chelydrae, Microphallus opacus, Protenes angustus, Spirorchis parvus, S. scripta, Telorchis attenuatus, and T. corti, the cestode Proteocephalus sp., and the nematodes Serpinema trispinosa and Spiroxys contortus are reported from Chrysemys picta belli. Except for P. angustus, all represent first reports from turtles in Canada. This is the first report of E. chelydrae from the host stomach, and the second report of M. opacus from naturally infected turtles.


1981 ◽  
Vol 54 (1) ◽  
pp. 165-178 ◽  
Author(s):  
Gary C. Packard ◽  
Mary J. Packard ◽  
Thomas J. Boardman

2006 ◽  
Vol 84 (8) ◽  
pp. 1129-1137 ◽  
Author(s):  
I.R. Caldwell ◽  
V.O. Nams

Orientation mechanisms allow animals to spend minimal time in hostile areas while reaching needed resources. Identification of the specific mechanism used by an animal can be difficult, but examining an animal's path in familiar and unfamiliar areas can provide clues to the type of mechanism in use. Semiaquatic turtles are known to use a homing mechanism in familiar territory to locate their home lake while on land, but little is known about their ability to locate habitat in unfamiliar territory. We tested the tortuosity and orientation of 60 eastern painted turtles ( Chrysemys picta picta (Schneider, 1783)). We released turtles at 20 release points located at five distances and in two directions from two unfamiliar lakes. Turtle trails were quite straight (fractal dimension between 1.1 and 1.025) but were not oriented towards water from any distance (V-test; u < 0.72; P > 0.1). Turtles maintained their initially chosen direction but either could not detect water or were not motivated to reach it. Furthermore, paths were straighter at larger spatial scales than at smaller spatial scales, which could not have occurred if the turtles had been using a correlated random walk. Turtles must therefore be using a reference stimulus for navigation even in unfamiliar areas.


1991 ◽  
Vol 125 (2) ◽  
pp. 245 ◽  
Author(s):  
Nat B. Frazer ◽  
J. Whitfield Gibbons ◽  
Judith L. Greene

2021 ◽  
Author(s):  
Omar Lenzi ◽  
Arpat Ozgul ◽  
Roberto Salguero-Gomez ◽  
Maria Paniw

Temporal variation in vital rates (e.g., survival, reproduction) can decrease the long-term mean performance of a population. Species are therefore expected to evolve demographic strategies that counteract the negative effects of vital rate variation on the population growth rate. One key strategy, demographic buffering, is reflected in a low temporal variation in vital rates critical to population dynamics. However, comparative studies in plants have found little evidence for demographic buffering, and little is known about the prevalence of buffering in animal populations. Here, we used vital rate estimates from 31 natural populations of 29 animal species to assess the prevalence of demographic buffering. We modeled the degree of demographic buffering using a standard measure of correlation between the standard deviation of vital rates and the sensitivity of the population growth rate to changes in such vital rates across populations. We also accounted for the effects of life-history traits, i.e., age at first reproduction and spread of reproduction across the life cycle, on these correlation measures. We found no strong or consistent evidence of demographic buffering across the study populations. Instead, key vital rates could vary substantially depending on the specific environmental context populations experience. We suggest that it is time to look beyond concepts of demographic buffering when studying natural populations towards a stronger focus on the environmental context-dependence of vital-rate variation.


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