The effect of constant and fluctuating incubation temperatures on the phenotype of black ratsnakes (Elaphe obsoleta)

2008 ◽  
Vol 86 (8) ◽  
pp. 882-889 ◽  
Author(s):  
L. D. Patterson ◽  
G. Blouin-Demers

According to the maternal manipulation hypothesis, females manipulate the phenotypes of their offspring by selecting favourable incubation conditions. In oviparous black ratsnakes ( Elaphe obsoleta Say in James, 1823), females manipulate offspring phenotype through nest-site selection. This study aimed to determine whether the thermal mean and variance of the incubation regime affect fitness-related traits in hatchlings. We incubated 136 eggs in a split-clutch design at two thermal means (26 and 29 °C) and variances (constant and ±3 °C). Hatchlings incubated at higher temperatures hatched earlier, were longer, faster, and less defensive. Hatchlings incubated at constant temperatures hatched earlier and were longer. For athletic performance, there was a significant interaction between temperature mean and variance: hatchlings incubated at 29 °C swam faster, had a lower muscular strength, and righted themselves equally fast when incubated at constant temperatures, whereas hatchlings incubated at 26 °C were stronger, swam faster, and righted themselves more slowly. Overall, constant incubation temperatures produced hatchlings with phenotypes favouring higher survival than fluctuating temperatures, but the effect of thermal variance was not as pronounced as the effect of thermal mean. Therefore, we found some support for the hypothesis that black ratsnakes prefer communal over single-female nests because communal nests have higher, more constant temperatures.

2017 ◽  
Vol 38 (3) ◽  
pp. 363-369 ◽  
Author(s):  
David G. Chapple ◽  
Susan N. Keall ◽  
Charles H. Daugherty ◽  
Kelly M. Hare

Nest-site selection in ectothermic animals influences hatching success and offspring phenotype, and it is predicted that females should choose nesting sites that maximise their reproductive fitness, ultimately through the reproductive success of their offspring. We completed nest-site choice experiments on a nocturnal lizard, the egg-laying skink (Oligosoma suteri), to determine whether eggs (and subsequent hatchlings) from cooler nests do better at cooler incubation temperatures, and conversely if those laid in warmer nests perform better at warmer incubation temperatures. We provided a simple nest-choice experiment, with oviposition-retreat sites available in either a hot or a cool sector of the enclosure; in the wild females nest under objects. Female O. suteri laid eggs both during the day and night, and nested more in the hot than cool sector. Eggs from each clutch were split across three egg incubation temperatures (18°C, 22°C, 26°C) to decouple the impact of initial nest-site choice from the subsequent incubation temperature regime. Whether eggs were initially laid in the hot or cool sector was not related to hatching success, offspring phenotype or offspring locomotor performance. We conclude that offspring phenotype and performance is primarily influenced by the temperature during incubation, rather than the initial thermal environment of the nest location. Thus, female O. suteri may select warmer nesting sites to ensure higher incubation temperature and enhanced offspring fitness.


2012 ◽  
Vol 8 (3) ◽  
pp. 372-374 ◽  
Author(s):  
Joshua J. Amiel ◽  
Richard Shine

A hatchling reptile's sex, body size and shape, and locomotor performance can be influenced not only by its genes, but also by the temperature that it experiences during incubation. Can incubation temperature also affect a hatchling's cognitive skills? In the scincid lizard Bassiana duperreyi , higher incubation temperatures enhanced the resultant hatchling's learning performance. Hence, factors such as maternal nest-site selection and climate change affect not only the size, shape and athletic abilities of hatchling reptiles, but also their ability to learn novel tasks.


2004 ◽  
Vol 82 (3) ◽  
pp. 449-456 ◽  
Author(s):  
Gabriel Blouin-Demers ◽  
Patrick J Weatherhead ◽  
Jeffrey R Row

Nest-site selection is the only behaviour that can be considered parental care in most oviparous reptiles because eggs are abandoned after laying and because incubation conditions resulting from nest-site selection can have profound effects on offspring. During a 7-year study of black rat snakes, Elaphe obsoleta (Say in James, 1823), we investigated phenotypic effects of incubation temperature on hatchlings, monitored temperatures in nests, and determined the preferred nesting temperature. Temperatures of communal nests were higher than those of single-female nests. In the laboratory, females preferred to nest at temperatures most similar to those of communal nests. Hatchlings from eggs incubated at temperatures similar to those in the warmer communal nests hatched faster, were longer, swam faster, were less aggressive, and had fewer scale anomalies than hatchlings from eggs incubated at temperatures similar to those in single nests. A possible disadvantage of communal nests is that eggs in communal nests may be at greater risk to parasitism by Nicrophorus pustulatus (Herschel, 1807). The incubation experiment allowed a test of a key assumption of a model proposed to explain environmental sex determination. Contrary to that assumption, we found no evidence that incubation temperature affected males and females differently. Our results might explain why temperature-dependent sex determination appears not to occur in snakes.


2019 ◽  
Author(s):  
Lauren Schaale ◽  
◽  
Joseph Baxley ◽  
Narcisa Pricope ◽  
Raymond M. Danner

2021 ◽  
Vol 26 ◽  
pp. e01524
Author(s):  
Karim Loucif ◽  
Mohamed Cherif Maazi ◽  
Moussa Houhamdi ◽  
Haroun Chenchouni

The Auk ◽  
2001 ◽  
Vol 118 (3) ◽  
pp. 727-735 ◽  
Author(s):  
Jason Jones ◽  
Raleigh J. Robertson

Abstract We examined habitat selection by breeding Cerulean Warblers (Dendroica cerulea) at three spatial scales in eastern Ontario over three years (1997–1999). Territories were characterized by well-spaced large trees, with high canopies and dense foliage cover at heights between 12–18 m. Nesting habitat additionally was characterized by dense foliage cover above 18 m. The results of our nest-patch (0.04 ha circle around nest) and nest-site (0.01 ha circle) analyses indicate that male Cerulean Warblers may take active roles in nest-site selection when selecting territories. We conclude from our nest-patch and nest-site selection analyses that territories likely contain multiple nest patches and sites and that male Cerulean Warblers may defend areas with multiple nest patches or sites, which may attract females to settle with them. Whether or not Cerulean Warbler females use nest-site availability as a mate- or territory-choice cue remains unknown. We also tested the validity of a commonly made assumption that a random sampling of habitat by researchers is representative of the habitat actually available to birds and found that, in our study area, the assumption was invalid. Taken together, our results point toward the need to maintain sizeable stands of mature, deciduous forest to ensure the persistence of Cerulean Warblers in eastern Ontario. Population characteristics such as lower minimum area requirements and a resilience to habitat disturbance may make that an easier job in eastern Ontario than elsewhere in this species' breeding range.


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