Measurement of Eggshell Thickness Between two Species of Sceloporus Lizards Using Scanning Electron Microscopy

Thermal environment exerts a strong influence on lizard life histories by constraining seasonal activity time, fecundity, growth, and embryonic development. in cold climates, extending the duration of egg retention within the female's body permits embryos to develop more rapidly than would be possible at ambient nest temperatures. The duration of egg retention time in the oviduct is largely constrained by the ability of the growing embryo to uptake oxygen and release carbon dioxide. Parchment shelled eggs of most squamates (lizards, snakes, and amphisbaenians) while permeable to water and gases, also acts as a diffusive barrier to gas exchange. As a result, most taxa with extended egg retention exhibit a concomitant reduction in eggshell thickness.To assess the influence of thermal environment on egg retention time, I sampled eggs from the lizards Sceloporus occidentalis and Sceloporus graciosus(Phrynosomatidae) from three populations at high, intermediate, and low elevation, in the San Gabriel Mountains of Southern California.

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Effect of thermal environment on life histories of free living Drosophila melanogaster and D. subobscura

Oecologia ◽

10.1007/bf00334650 ◽

1996 ◽

Vol 108 (2) ◽

pp. 262-272 ◽

Cited By ~ 15

Author(s):

Ranka Junge-Berberović

Keyword(s):

Drosophila Melanogaster ◽

Life Histories ◽

Thermal Environment ◽

Free Living

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Orientation and homing behavior as a measure of affinity for the home range in two species of Iguanid lizards

Amphibia-Reptilia ◽

10.1163/156853891x00022 ◽

1991 ◽

Vol 12 (4) ◽

pp. 373-384 ◽

Cited By ~ 6

Author(s):

Craig Guyer

Keyword(s):

Home Range ◽

Life Histories ◽

Egg Laying ◽

Single Site ◽

Long Distance ◽

Homing Behavior ◽

Sceloporus Graciosus ◽

Gravid Females ◽

The Relationship ◽

Natural Means

AbstractThe relationship between home range affinity and homing ability was studied in Phrynosoma douglassi and Sceloporus graciosus in southeastern Idaho. Movement patterns for P. douglassi were typical of an animal moving from one site of activity to other sites, whereas S. graciosus movements were typical of an animal using a single site of activity. Only S. graciosus was able to orient towards the home range when displaced, indicating an affinity for this site. Adult S. graciosus oriented and homed more consistently than did juveniles. P. douglassi did not orient homeward when displaced and returned less frequently than did S. graciosus. Recapture locations along with data regarding homeward orientation and homing indicate that P. douglassi has a lesser affinity than does S. graciosus for the home range. Some gravid females of both species left the home range to deposit eggs or young and later returned. Use of areas outside the home range for egg-laying and birthing and movements out of the home range resulting from chases by predators may represent natural means of displacement that select for homing behavior. Because most lizards experience only short displacements during their life histories, long distance homing reported for snakes, turtles, and salamanders is absent.

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Habitat and Prey Selection of Sceloporus Occidentalis and Sceloporus Graciosus

Ecology ◽

10.2307/1936437 ◽

1976 ◽

Vol 57 (3) ◽

pp. 531-541 ◽

Cited By ~ 22

Author(s):

Barbara R. Rose

Keyword(s):

Prey Selection ◽

Sceloporus Occidentalis ◽

Sceloporus Graciosus ◽

Selection Of

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Production of Nonadhesive Eggs by Flathead Chub and Implications for Downstream Transport and Conservation

Journal of Fish and Wildlife Management ◽

10.3996/022016-jfwm-018 ◽

2016 ◽

Vol 7 (2) ◽

pp. 434-443 ◽

Cited By ~ 3

Author(s):

Kevin R. Bestgen ◽

Harry J. Crockett ◽

Matthew R. Haworth ◽

Ryan M. Fitzpatrick

Keyword(s):

Great Plains ◽

Life Histories ◽

Habitat Type ◽

Volume Ratio ◽

Laboratory Culture ◽

Limited Information ◽

Egg Retention ◽

In Captivity ◽

Reproductive Life ◽

Pelagic Spawning

Abstract Plains stream fishes in North America, including flathead chub Platygobio gracilis, are negatively affected by stream-flow alterations and fragmentation, and limited information on egg type and reproductive strategy hinders their conservation. On the basis of several lines of evidence, including laboratory culture, observations of reproduction in captivity, and capture and rearing of eggs from Fountain Creek, Colorado, we report that flathead chub produce nonadhesive eggs. Flathead chub eggs are relatively small at 2.3 mm mean diameter, have a greater yolk-to-egg volume ratio and thus sink faster, and take longer to hatch, compared with nonadhesive eggs from pelagic spawning species. Flathead chub are also longer lived compared with pelagic spawning species and the wider variety of habitat types they occupy may influence upstream egg retention. Although spawning mode (e.g., pelagic, lithopelagic, other) is incompletely known for flathead chub, habitat needs in terms of flows and reach lengths suitable for reproduction and recruitment may vary with habitat type but may be similar to that for other pelagic spawning species. Accommodating specialized reproductive life histories of fishes, including egg type and transport characteristics, in stream conservation planning may assist with maintaining or enhancing populations of all Great Plains cyprinids, including increasingly rare flathead chub.

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An enigmatic mass mortality event of Blanding’s turtles (Emydoidea blandingii) in a protected area

Canadian Journal of Zoology ◽

10.1139/cjz-2020-0204 ◽

2021 ◽

Author(s):

D.M.L. Gasbarrini ◽

David Lesbarrères ◽

A. Sheppard ◽

Jacqueline Litzgus

Keyword(s):

Protected Area ◽

Life Histories ◽

Mass Mortality ◽

Water Levels ◽

Emydoidea Blandingii ◽

Leopard Frogs ◽

Mass Mortality Event ◽

Concomitant Reduction ◽

Site Water ◽

Trail Cameras

Mass mortality events (MMEs) can remove up to 90% of individuals in a population, and are especially damaging to population viability of long-lived species with slow life histories. Our goal was to elucidate the cause(s) of a MME of 53 Blanding’s turtles (Emydoidea blandingii (Holbrook, 1838)), a globally endangered species, in a protected area. We investigated disease, winter-kill, and depredation as potential causes of the mortality. The turtle carcasses lacked soft tissue to test for disease, so we examined tissue from co-occurring live leopard frogs (Lithobates pipiens (Schreber, 1782)) and found no evidence of ranavirus, indicating that the disease was not present at our study site. Water temperature and dissolved aquatic oxygen at known overwintering sites and sites which yielded carcasses did not differ, suggesting that winter-kill did not cause the MME. Carcass condition, comparisons to descriptions of turtle depredation events in the literature, and trail cameras paired with turtle decoys, identified potential predators within the study site, and suggested that mass depredation, enabled by low water levels and a concomitant reduction in aquatic habitat, was the most likely cause of mortality. Our study can inform conservation of the study population and the management of MMEs of long-lived species elsewhere.

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