Implications of movement patterns for gene flow in black rat snakes (Elaphe obsoleta)

2002 ◽  
Vol 80 (7) ◽  
pp. 1162-1172 ◽  
Author(s):  
Gabriel Blouin-Demers ◽  
Patrick J Weatherhead
Keyword(s):  
Gene Flow ◽  
Movement Patterns ◽  
Genetic Connectivity ◽  
Mating Season ◽  
Elaphe Obsoleta ◽  
Juvenile Dispersal ◽  
Black Rat ◽  
Black Rat Snakes ◽  
Males And Females ◽  
The Mean

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.

Spatial and activity patterns of black rat snakes (Elaphe obsoleta) from radiotelemetry and recapture data

1989 ◽  
Vol 67 (2) ◽  
pp. 463-468 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Drew J. Hoysak
Keyword(s):  
Activity Patterns ◽  
Home Ranges ◽  
Accurate Assessment ◽  
Radio Tracking ◽  
Elaphe Obsoleta ◽  
Black Rat ◽  
Black Rat Snakes ◽  
Below Ground ◽  
Males And Females ◽  
Male Activity

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.

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
Keyword(s):  
Sex Determination ◽  
Site Selection ◽  
Nest Site ◽  
Incubation Temperature ◽  
Nest Site Selection ◽  
Elaphe Obsoleta ◽  
Temperature Dependent ◽  
Black Rat ◽  
Black Rat Snakes ◽  
Males And Females

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.

Habitat Use by Black Rat Snakes (Elaphe obsoleta obsoleta) in Fragmented Forests

Ecology ◽  
2001 ◽  
Vol 82 (10) ◽  
pp. 2882 ◽  
Author(s):  
Gabriel Blouin-Demers ◽  
Patrick J. Weatherhead
Keyword(s):  
Habitat Use ◽  
Elaphe Obsoleta ◽  
Black Rat ◽  
Black Rat Snakes ◽  
Fragmented Forests

Homing to Food by Black Rat Snakes (Elaphe obsoleta)

Copeia ◽  
1990 ◽  
Vol 1990 (4) ◽  
pp. 1164 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Ian C. Robertson
Keyword(s):  
Elaphe Obsoleta ◽  
Black Rat ◽  
Black Rat Snakes

Temporal and thermal aspects of hibernation of black rat snakes (Elaphe obsoleta) in Ontario

1989 ◽  
Vol 67 (9) ◽  
pp. 2332-2335 ◽  
Author(s):  
Patrick J. Weatherhead
Keyword(s):  
Radio Telemetry ◽  
Day Length ◽  
Thermal Gradients ◽  
Elaphe Obsoleta ◽  
Limited Sample ◽  
Endogenous Rhythms ◽  
Black Rat ◽  
Black Rat Snakes ◽  
Considerable Individual Variation ◽  
Insight Into

Radio telemetry was used to determine the time of emergence from and entry into communal hibernacula by black rat snakes (Elaphe obsoleta obsoleta) and to gain insight into the proximate factors involved in these behaviours. Emergence in mid-April appears not to be triggered by marked reversal of thermal gradients in the hibernaculum as has been proposed, or by changes in day length. By default, endogenous rhythms seem most likely to be responsible. Entry in early October may be triggered in part by outside temperatures. Even with the limited sample size used in this study, considerable individual variation in emergence and entry patterns was observed. Through the winter the snakes steadily got colder, reaching their coldest point just before emergence. The 7-month hibernation period was substantially longer than has been observed for more southerly populations. Given the period of inactivity immediately before and following hibernation, the active period is less than 4 months, which perhaps explains why the population in this study is the northernmost in the species' distribution.

Thermal Ecology of Black Rat Snakes (Elaphe obsoleta) in a Thermally Challenging Environment

Ecology ◽  
2001 ◽  
Vol 82 (11) ◽  
pp. 3025 ◽  
Author(s):  
Gabriel Blouin-Demers ◽  
Patrick J. Weatherhead
Keyword(s):  
Thermal Ecology ◽  
Elaphe Obsoleta ◽  
Black Rat ◽  
Black Rat Snakes ◽  
Challenging Environment
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