Phenotypic consequences of nest-site selection in black rat snakes (Elaphe obsoleta)

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.

2020 ◽  
Vol 91 ◽  
pp. 102624
Author(s):  
Marco A. López-Luna ◽  
Jesús González-Soberano ◽  
Mauricio González-Jáuregui ◽  
Armando H. Escobedo-Galván ◽  
Emilio A. Suárez-Domínguez ◽  
...  

2002 ◽  
Vol 80 (7) ◽  
pp. 1162-1172 ◽  
Author(s):  
Gabriel Blouin-Demers ◽  
Patrick J Weatherhead

Gene flow is fundamental to evolutionary processes but knowledge about movements of individuals and their offspring necessary for gene flow is scant. We investigated potential ecological components of genetic connectivity within a population of black rat snakes (Elaphe obsoleta) by radio-tracking 82 individuals. Because adult black rat snakes are highly faithful to their hibernaculum, gene flow between hibernaculum populations has to occur through mating between members of different hibernacula or through juvenile dispersal. The present study was the first to assess the spatial dispersion of a complete network of hibernacula. The mean distance between the nearest-neighbour hibernacula was 811 m, which was less than the mean distances that reproductive males and females were found from their hibernacula during the mating season. Estimates of maximum distances individuals were from their hibernacula during the mating season indicated that, on average, a female was likely to mate with males that came from two hibernacula away from the female's own hibernaculum. Both males and females appeared to contribute actively to gene flow by moving more and increasing their distance from their hibernacula during the mating season. In addition, on average, females nested closer to a hibernaculum other than the one they attended, thereby potentially increasing the likelihood that their offspring would join hibernacula other than their mothers'. Thus, spatial and movement patterns of male and female black rat snakes are consistent with genetic evidence of extensive out-breeding among local hibernaculum populations.


1989 ◽  
Vol 67 (2) ◽  
pp. 463-468 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Drew J. Hoysak

We used 323 capture records collected from 1981 to 1987 and intensive radio-tracking data from 11 individuals studied in 1982 and 1983 to determine spatial and activity patterns of black rat snakes (Elaphe obsoleta) in eastern Ontario. In general the snakes remained in their home ranges (which usually did not include the snakes' hibernating sites) until late September or early October and then moved directly to the communal hibernacula and went below ground. Emergence occurred in late April and early May and most snakes returned to their home ranges without delay. The home ranges of males averaged over three times the size of those of females. Males also moved more often and farther than females. Accurate assessment of these patterns would not have been possible without radiotelemetry. Males were captured more frequently than females during the mating season, although they were most active later in the summer. The peak in captures may be due to males spending more time in open areas (where they were most often captured) during the breeding season because doing so somehow increases their success in locating females. Activity and movement patterns follow quite different patterns in males and females. Male activity may be determined by thermoregulatory factors while females may be affected more by reproduction.


2020 ◽  
Vol 130 (2) ◽  
pp. 320-335
Author(s):  
Ariel L Steele ◽  
Daniel A Warner

Abstract The developmental environment plays a pivotal role in shaping fitness-relevant phenotypes of all organisms. Phenotypes are highly labile during embryogenesis, and environmental factors experienced early in development can have profound effects on fitness-relevant traits throughout life. Many reptiles exhibit temperature-dependent sex determination (TSD), whereby temperature during embryonic development permanently determines offspring sex. The leading hypothesis for the adaptive significance of TSD posits that egg incubation temperature differentially affects the fitness of males vs. females so that each sex is produced at its optimal temperature. The goal of this research is to address this hypothesis by quantifying the sex-specific effects of incubation temperature on phenotypes and survival in a lizard (Agama picticauda) with TSD. By incubating eggs under constant and fluctuating temperatures, we demonstrated that incubation temperature affects fitness-relevant phenotypes in A. picticauda; but males and females had similar reaction norms. However, females produced from female-biased incubation temperatures had greater survival than those from male-biased temperatures, and male survival was lowest for individuals produced from a female-biased temperature. In addition, eggs incubated at male-biased temperatures hatched earlier than those incubated at female-biased temperatures, which may have sex-specific consequences later in life as predicted by models for the adaptive significance of TSD.


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.


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

2021 ◽  
pp. 1-9
Author(s):  
Horacio Merchant-Larios ◽  
Verónica Díaz-Hernández ◽  
Diego Cortez

The discovery in mammals that fetal testes are required in order to develop the male phenotype inspired research efforts to elucidate the mechanisms underlying gonadal sex determination and differentiation in vertebrates. A pioneer work in 1966 that demonstrated the influence of incubation temperature on sexual phenotype in some reptilian species triggered great interest in the environment’s role as a modulator of plasticity in sex determination. Several chelonian species have been used as animal models to test hypotheses concerning the mechanisms involved in temperature-dependent sex determination (TSD). This brief review intends to outline the history of scientific efforts that corroborate our current understanding of the state-of-the-art in TSD using chelonian species as a reference.


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