scispace - formally typeset
Search or ask a question
Author

Richard C. Vogt

Bio: Richard C. Vogt is an academic researcher from National Institute of Amazonian Research. The author has contributed to research in topics: Turtle (robot) & Podocnemididae. The author has an hindex of 30, co-authored 117 publications receiving 3785 citations. Previous affiliations of Richard C. Vogt include University of Wisconsin-Madison & Carnegie Museum of Natural History.


Papers
More filters
Journal ArticleDOI
Monika Böhm1, Ben Collen1, Jonathan E. M. Baillie1, Philip Bowles2  +240 moreInstitutions (95)
TL;DR: The results provide the first analysis of the global conservation status and distribution patterns of reptiles and the threats affecting them, highlighting conservation priorities and knowledge gaps which need to be addressed urgently to ensure the continued survival of the world’s reptiles.

720 citations

Journal ArticleDOI
07 Dec 1979-Science
TL;DR: The sex of hatchling map turtles is determined by incubation temperature of eggs in the laboratory as well as in nature, and temperature controls sex differentiation rather than causing a differential mortality of sexes.
Abstract: The sex of hatchling map turtles is determined by incubation temperature of eggs in the laboratory as well as in nature. Temperature controls sex differentiation rather than causing a differential mortality of sexes. Temperature has no effect on sex determination in a soft-shelled turtle.

329 citations

Journal ArticleDOI
TL;DR: The question of adaptive sex ratio is addressed in much of the recent evolutionary literature and there is a growing concern that many species may lack the type of genetic variation for sex ratio on which these evolutionary models depend.
Abstract: The question of adaptive sex ratio is addressed in much of the recent evolutionary literature (a few examples are Hamilton, 1967; Trivers and Willard, 1973; Maynard Smith, 1978; Charnov, 1979; Williams, 1979; Charnov et al., 1981). ('Sex ratio' refers to the primary sex ratio unless indicated otherwise.) The common method of investigation has been to formulate an evolutionary model and then to compare a predicted equilibrium with observed sex ratios. This methodology usually makes three implicit assumptions: (1) heritable variation of the primary sex ratio exists, (2) the variation is due to genes with arbitrarily small effect, and (3) the variation is inherited autosomally. There is, however, a growing concern that many species may lack the type of genetic variation for sex ratio on which these evolutionary models depend (Maynard Smith, 1978; Williams, 1979). Studies of species with sex chromosomes, such as Drosophila, chickens, and domesticated mammals, indicate the existence of heritable sex ratio variation in some cases but not others (King, 1918; Falconer, 1954; Weir, 1962; Bar-Anan and Robertson, 1975; Foster and McSherry, 1980; Toro, unpubl.). Even when heritable variation is indicated, the data in many cases do not distinguish between variation of the pri-

205 citations

Journal ArticleDOI
TL;DR: This is the first study to test the relationship between multiple paternity and ecological aspects of the reproductive ecology of turtles in the genus Podocnemis and number of fathers per nest to nesting period; clutch size; female size; and hatchling success.
Abstract: Genetic studies of multiple paternity are a valuable tool to gain information on the reproductive biology of turtles. We analyzed paternity type in Podocnemis sextuberculata and related number of fathers per nest to nesting period (beginning, middle, or end of nesting season); clutch size (number of eggs); female size; and hatchling success. Females were captured and maximum linear carapace lengths measured during the 60 days that encompass the nesting season at Rio Trombetas Biological Reserve (Para, Brazil). Nests were marked and blood samples collected from hatchlings. Six heterologous loci were used: five from Podocnemis unifilis and one from Podocnemis expansa. Hatchlings were analyzed from 23 nests, and the rate of multiple paternity was 100%. The mean number of fathers per nest was six (± 0.9), and no significant difference between number of fathers in a nest and nesting period. Similarly there was no significant relationship between number of fathers in a nest and female size or hatchling success rate. Number of fathers was, however, positively correlated with clutch size (Spearman correlation rho = 0.47; P > 0.05). To our knowledge, this is the first study to test the relationship between multiple paternity and ecological aspects of the reproductive ecology of turtles in the genus Podocnemis.

167 citations

Journal ArticleDOI
TL;DR: The order Testudines is, on average, more imperiled than all other larger orders (≥ 20 species) of Reptilia, Amphibia, Mammalia, or Aves, but has percentages of CR+EN and Threatened species and an ATL similar to those of Primates and Caudata (salamanders).
Abstract: We present a review and analysis of the conservation status and International Union for Conservation of Nature (IUCN) threat categories of all 360 currently recognized species of extant and recently extinct turtles and tortoises (Order Testudines). Our analysis is based on the 2018 IUCN Red List status of 251 listed species, augmented by provisional Red List assessments by the IUCN Tortoise and Freshwater Turtle Specialist Group (TFTSG) of 109 currently unlisted species of tortoises and freshwater turtles, as well as re-assessments of several outdated IUCN Red List assessments. Of all recognized species of turtles and tortoises, this combined analysis indicates that 20.0% are Critically Endangered (CR), 35.3% are Critically Endangered or Endangered (CR+EN), and 51.9% are Threatened (CR+EN+Vulnerable). Adjusting for the potential threat levels of Data Deficient (DD) species indicates that 56.3% of all data-sufficient species are Threatened. We calculated percentages of imperiled species and modifi...

167 citations


Cited by
More filters
Journal Article
Fumio Tajima1
30 Oct 1989-Genomics
TL;DR: It is suggested that the natural selection against large insertion/deletion is so weak that a large amount of variation is maintained in a population.

11,521 citations

Journal ArticleDOI
TL;DR: Estimates of extinction rates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way and a window of opportunity is rapidly closing.
Abstract: The oft-repeated claim that Earth’s biota is entering a sixth “mass extinction” depends on clearly demonstrating that current extinction rates are far above the “background” rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we use a recent estimate of a background rate of 2 mammal extinctions per 10,000 species per 100 years (that is, 2 E/MSY), which is twice as high as widely used previous estimates. We then compare this rate with the current rate of mammal and vertebrate extinctions. The latter is conservatively low because listing a species as extinct requires meeting stringent criteria. Even under our assumptions, which would tend to minimize evidence of an incipient mass extinction, the average rate of vertebrate species loss over the last century is up to 100 times higher than the background rate. Under the 2 E/MSY background rate, the number of species that have gone extinct in the last century would have taken, depending on the vertebrate taxon, between 800 and 10,000 years to disappear. These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way. Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing.

2,544 citations

Journal ArticleDOI

[...]

2,428 citations

Journal ArticleDOI
TL;DR: The lability of sex-determination systems in fish makes some species sensitive to environmental pollutants capable of mimicking or disrupting sex hormone actions, and such observations provide important insight into potential impacts from endocrine disruptors, and can provide useful monitoring tools for impacts on aquatic environments.

2,283 citations

Journal ArticleDOI
01 Oct 1987-Heredity
TL;DR: It is found that the heritability of morphological traits is significantly lower for ectotherms than it is for endotherms which may in part be a result of the strong correlation between life history and body size for many ectotherm.
Abstract: The hypothesis that traits closely associated with fitness will generally possess lower heritabilities than traits more loosely connected with fitness is tested using 1120 narrow sense heritability estimates for wild, outbred animal populations, collected from the published record. Our results indicate that life history traits generally possess lower heritabilities than morphological traits, and that the means, medians, and cumulative frequency distributions of behavioural and physiological traits are intermediate between life history and morphological traits. These findings are consistent with popular interpretations of Fisher's (1930, 1958) Fundamental Theorem of Natural Selection, and Falconer (1960, 1981), but also indicate that high heritabilities are maintained within natural populations even for traits believed to be under strong selection. It is also found that the heritability of morphological traits is significantly lower for ectotherms than it is for endotherms which may in part be a result of the strong correlation between life history and body size for many ectotherms.

1,483 citations