Species-isolating mechanisms in a mating system with male mate choice (garter snakes, Thamnophis spp.)

2004 ◽  
Vol 82 (7) ◽  
pp. 1091-1098 ◽  
Author(s):  
Richard Shine ◽  
Benjamin Phillips ◽  
Heather Waye ◽  
Michael Lemaster ◽  
Robert T Mason
Keyword(s):  
Warm Season ◽  
Mate Recognition ◽  
Early Spring ◽  
Morphological Data ◽  
Thamnophis Sirtalis ◽  
Garter Snakes ◽  
Temporal Separation ◽  
Ambient Temperatures ◽  
Male Mate ◽  
Species Specific

Reproductive isolation between sympatric taxa can be maintained by specific mate-recognition behaviours or by ecological divergence that reduces interspecific contact during reproduction. Common garter snakes, Thamnophis sirtalis (L., 1758), and plains garter snakes, Thamnophis radix (Baird and Girard, 1853), are sympatric over large areas, but morphological data suggest that the prezygotic isolation between these two species partially breaks down in a severely cold part of their joint range in Manitoba. Courtship trials show that male T. radix court intensely over a narrower range of (higher) ambient temperatures than do male T. sirtalis. Males selectively court females of their own species, but male T. radix are less choosy than male T. sirtalis. Hexane extracts of female skin lipids also elicited species-specific courtship. Although this male preference for species-specific pheromones contributes to species isolation, it is not strong enough to completely separate the two taxa. The absence of hybridization over most of the sympatric range may depend on the timing of mating (early spring, near the hibernation den). Differences between the species in hibernation-site selection and the timing of spring emergence break down in central Manitoba because severely cold winter temperatures force both species together into the few available hibernation (and thus, mating) sites, and the short warm season reduces temporal separation in emergence (and thus, mating) seasons.

Body temperatures and movements of hibernating snakes (Crotalus and Thamnophis) and thermal gradients of natural hibernacula

1989 ◽  
Vol 67 (1) ◽  
pp. 108-114 ◽  
Author(s):  
J. Malcolm Macartney ◽  
Karl W. Larsen ◽  
Patrick T. Gregory
Keyword(s):  
Thermal Gradient ◽  
Reference Site ◽  
Early Spring ◽  
Garter Snake ◽  
Thamnophis Sirtalis ◽  
Garter Snakes ◽  
Body Temperatures ◽  
Ambient Temperatures ◽  
Crotalus Viridis ◽  
Northern Alberta

Although temperate zone snakes spend a large part of each year in hibernation, we know relatively little about their behavior during this part of the annual cycle. We used radiotelemetry to monitor temperatures and movements of hibernating rattlesnakes (Crotalus viridis) in southern British Columbia and garter snakes (Thamnophis sirtalis) in northern Alberta, and measured thermal profiles inside their hibernacula. A reference site near the garter snake hibernaculum, superficially resembling a winter den but not used by snakes, also was monitored. A thermal gradient (temperature increasing with depth) formed during the winter in the rattlesnake den, but only minimally so in the garter snake den. Differences in thermal profiles were attributed to differences in subsurface geomorphology. The reference site exhibited much greater temperature fluctuation than the den itself, with lethal temperatures prevailing throughout the winter. Therefore, suitable hibernation sites may be limited in some areas despite a superficial appearance of abundance. As ambient temperatures declined during early winter, snakes made lateral movements inside their hibernacula, and exhibited changes in body temperature which we interpreted as movements to warmer (deeper) microsites. Body temperatures recorded during winter ranged between 2 and 7 °C. In early spring the thermal gradient collapsed and the rattlesnake den gradually underwent a uniform increase in temperature. A similar increase in subterranean temperatures occurred in the garter snake den. Temperature change was perhaps a stimulus for emergence in rattlesnakes, but possibly not in garter snakes. The hypothesis that hibernating snakes orient along a seasonally reversing thermal gradient is not unambiguously supported.

Female mimicry in garter snakes: behavioural tactics of "she-males" and the males that court them

2000 ◽  
Vol 78 (8) ◽  
pp. 1391-1396 ◽  
Author(s):  
Richard Shine ◽  
David O'Connor ◽  
Robert T Mason
Keyword(s):  
Time Of Day ◽  
Early Spring ◽  
Thamnophis Sirtalis ◽  
Garter Snakes ◽  
Thermal Threshold ◽  
Male Attractiveness ◽  
Female Mimicry ◽  
Early Afternoon ◽  
Antipredator Responses ◽  
Locomotor Capacity

Red-sided garter snakes (Thamnophis sirtalis parietalis) in central Manitoba court and mate in early spring soon after emerging from communal overwintering dens. Some males ("she-males") produce female-like skin pheromones, and hence attract courtship from other males. Studies at a den near Inwood, Manitoba, support and extend results from work at other dens. She-males were males that had recently emerged from hibernation and had not yet regained full locomotor capacity or muscle strength. She-males resembled "he-males" rather than females in their antipredator responses, including the thermal threshold at which they fled from a simulated predator (a plastic crow) rather than remaining stationary and displaying. Males courting she-males were cooler than those courting females; nonetheless they were more likely to flee when we approached them. Compared with courting groups focussed on females, groups around she-males were smaller, consisted predominantly of smaller he-males, and were found over a more restricted time of day (early afternoon). Arena trials confirmed that she-males are disproportionately courted by small rather than large he-males, and clarified other aspects of she-male attractiveness and behaviour. She-males attracted more intense courtship when large females were absent. She-males courted less vigorously when large he-males were present, especially when they were vigorously courted themselves. Overall, our data reveal hitherto-unsuspected complexity in the behavioural tactics of reproducing garter snakes.

Control of length of the courtship season in the red-sided garter snake, Thamnophis sirtalis parietalis: the role of temperature

1989 ◽  
Vol 67 (4) ◽  
pp. 987-993 ◽  
Author(s):  
Randolph W. Krohmer ◽  
David Crews
Keyword(s):  
Courtship Behavior ◽  
Temperature Fluctuations ◽  
Thamnophis Sirtalis ◽  
Garter Snakes ◽  
Ambient Temperatures ◽  
Thamnophis Sirtalis Parietalis ◽  
Laboratory Populations ◽  
Influence Of Temperature On ◽  
The Central Nervous System

The influence of temperature on the length and intensity of the courtship season was examined in both field and laboratory populations of red-sided garter snakes (Thamnophis sirtalis parietalis) over a 2-year period. Snakes were exposed to fluctuations in temperature following emergence from hibernation and activation of courtship behavior. In the field, males were exposed to four temperature regimens: extended hibernation (0L:24D, 4 ± 1.5 °C), cool (14L:10D, 12 ± 2.3° C), warm (14L:10D, 28 °C:ambient), or control (ambient temperatures and light). Control animals exhibited courtship behavior fluctuating in intensity with daily ambient temperatures. Animals exhibited high intensity courtship behavior when exposed to warm conditions following emergence from either natural hibernation or a secondary period of laboratory hibernation. Animals placed in the cool regimen were active but exhibited very little courtship behavior. Animals maintained under the cool regimen for 14 days did not initiate courtship behavior when placed in the warm regimen. Studies conducted in the laboratory support the field results. However, whereas animals maintained under the cool regimen for 14 days and then placed in the warm regimen exhibited dramatically reduced courtship behavior, animals placed in the warm regimen after 21 days under the cool regimen initiated courtship of normal intensity and duration. Following the end of all courtship behavior, males exposed to conditions of hibernation for a brief period reinitiated courtship behavior. These data suggest that the areas of the central nervous system critical for the perception of temperature fluctuations and initiation of courtship behavior remained sensitive in late spring. Following the end of the courtship season, females exposed to a brief period of hibernation also reinstated courtship behavior in noncourting males. These data suggest that the length of the courtship season ultimately may be controlled by the presence of attractive females.

Effects of humidity, temperature, and submergence behavior on survivorship and energy use in hibernating garter snakes, Thamnophis sirtalis

1989 ◽  
Vol 67 (10) ◽  
pp. 2486-2492 ◽  
Author(s):  
Jon P. Costanzo
Keyword(s):  
Mass Loss ◽  
Energy Use ◽  
Fat Body ◽  
Early Spring ◽  
Survival Duration ◽  
Thamnophis Sirtalis ◽  
Winter Mortality ◽  
Garter Snakes ◽  
Significant Survival ◽  
Additional Group

Desiccation is likely an important factor influencing winter mortality rates of terrestrially hibernating reptiles; however, this notion has not been rigorously tested. Groups of eastern garter snakes (Thamnophis sirtalis sirtalis) were matched for size and subsequently exposed to simulated hibernative conditions (5 or 12 °C, under different humidity regimes) during winter, for 165 days or until all group members expired. As garter snakes in some dens submerge during natural hibernation, an additional group was maintained in water at 5 °C. Snakes kept in air dehydrated and died (body water contents at death ranged from 62.1 to 67.8% of lean fresh mass), whereas snakes kept in water remained hydrated (median, 75.2%) and survived. Survival duration of air hibernators was inversely related to rate of mass loss, which in turn was strongly influenced by ambient humidity and temperature. Dehydration accounted for most of the mass lost in all air hibernators; however, owing to higher rates of nutrient consumption, mass loss was significantly greater in snakes kept at 12 °C (36%) than in snakes kept at 5 °C (29%). Changes in fat body and liver masses showed that snakes kept in air at 12 °C used the most energy whereas those kept in water at 5 °C used the least. Submerged hibernation behavior has significant survival value because under these conditions snakes remain hydrated during winter. Also, because submerged snakes conserve more stored energy during winter, their reproductive success may be enhanced when mating activities resume in early spring.

scholarly journals Biosemiotics and The Identification of Species-Specific Morphological Characters in The Spider Dysdera Erythrina (Araneae: Dysderidae)

2021 ◽  
Author(s):  
Joachim Schult ◽  
Onno A. Preik ◽  
Stefan Kirschner ◽  
Frank Friedrich
Keyword(s):  
Mate Recognition ◽  
Morphological Characters ◽  
Integrative Taxonomy ◽  
Communication Process ◽  
Morphological Data ◽  
Communication Processes ◽  
Peculiar Form ◽  
Identification Of Species ◽  
Intraspecific Communication ◽  
Species Specific

Abstract A biosemiotic approach of interpreting morphological data is apt to reveal morphological traits whose key role in intraspecific communication processes, such as specific mate recognition, has been overlooked so far. Certain genital structures of the haplogyne spider Dysdera erythrina (Walckenaer, 1802) serve as an example. In Dysdera erythrina the semi-circular sclerite at the tip of the male’s bulb fits exactly into the anterior diverticulum of the female’s endogyne. From the viewpoint of biosemiotics, which studies the production and interpretation of signs and codes in living systems, these structures are considered the morphological zones of an intraspecific communication process which forms one of the necessary prerequisites for sperm transfer and achievement of fertilisation. Thus, a biosemiotics-based species delimitation approach with its peculiar form of evaluation of morphological structures yields new insights for the multidisciplinary undertaking of modern integrative taxonomy.

Minimal overwintering temperatures of red-sided garter snakes (Thamnophis sirtalis parietalis): a possible cue for emergence?

2006 ◽  
Vol 84 (5) ◽  
pp. 771-777 ◽  
Author(s):  
Deborah I. Lutterschmidt ◽  
Michael P. LeMaster ◽  
Robert T. Mason
Keyword(s):  
Body Temperature ◽  
Early Spring ◽  
Ground Temperature ◽  
Thamnophis Sirtalis ◽  
Winter Dormancy ◽  
Garter Snakes ◽  
Body Temperatures ◽  
Thamnophis Sirtalis Parietalis ◽  
Spring Emergence ◽  
Insight Into

Red-sided garter snakes ( Thamnophis sirtalis parietalis (Say in James, 1823)) in Manitoba, Canada, undergo 8 months of continuous winter dormancy prior to spring emergence. As in other ectothermic species, increases in ground temperature may be the cue for emergence from winter dormancy in these populations. To test this hypothesis, we measured body temperatures during winter dormancy by surgically implanting small temperature loggers into 32 female red-sided garter snakes before they entered their native hibernaculum. The following spring, we recaptured seven of the snakes implanted with temperature loggers. Body temperature declined gradually from mid-September (14.7 ± 0.24 °C, mean  ± SE) to early April (1.1 ± 0.16 °C, mean ± SE) during winter dormancy, reaching minimal values approximately 1 month prior to spring emergence. Body temperatures of emerging snakes ranged from 0.5 °C during early spring to 6.3 °C during late spring (3.4 ± 0.84 °C, mean ± SE). These results do not support the hypothesis that an increase in ground temperature (and hence body temperature) is necessary for emergence from winter dormancy. We suggest that critically low temperatures (i.e., 0.5–1 °C) are a Zeitgeber entraining an endogenous circannual cycle that regulates snake emergence. These results offer new insight into the mechanisms regulating seasonal emergence from winter dormancy.

Phenological development and seasonal distribution of the rutherglen bug, Nnysius vinitor Bergroth (Hemiptera: Lygaeidae), on various hosts in Victoria, south-eastern Australia

1988 ◽  
Vol 78 (4) ◽  
pp. 673-682 ◽  
Author(s):  
Garrick McDonald ◽  
A. Mark Smith
Keyword(s):  
Rapid Development ◽  
Early Spring ◽  
Common Source ◽  
Body Temperatures ◽  
Ambient Temperatures ◽  
Polygonum Aviculare ◽  
Developmental Thresholds ◽  
Eastern Australia ◽  
Weed Hosts ◽  
Maximum Temperatures

AbstractPopulations of Nysius vinitor Bergroth were studied from 1979 to 1982 in two weed hosts, Arctotheca calendula and Polygonum aviculare, and eight irrigated sunflower crops in a summer cropping area of northern Victoria, Australia. The spring generation began with the adults colonizing flowering A.calendula plants in September and concluded with the rapid development of late stage nymphs and an exodus of adults from these plants from mid-November to December. Gradual invasion of sunflowers occurred mostly in late December and reached a peak at flowering, after which nymphs appeared. P. aviculare attracted adults from February and hosted a number of overlapping generations until winter. The weed sustained diminishing numbers of adults through the winter, except in 1982, when a further generation produced an early spring peak. Immigrant populations were regarded as a common source of adults for initiating the spring and summer generations. The rate of development of N. vinitor in spring was more rapid than that predicted by phenological simulation based on ambient temperatures and laboratory-derived day-degree estimates. This was attributed to increased body temperatures through absorption of solar radiation, and the simulation model was adjusted by increasing daily minimum and maximum temperatures by 1·3 and 5·5°C for young and older instars, respectively. This suggested that older nymphs have lower developmental thresholds or are better able to optimize body temperatures.

scholarly journals The taxonomic history of Indo-Papuan groundsnakes, genus Stegonotus Duméril et al., 1854 (Colubridae), with some taxonomic revisions and the designation of a neotype for S. parvus (Meyer, 1874)

Zootaxa ◽  
2018 ◽  
Vol 4512 (1) ◽  
pp. 1
Author(s):  
CHRISTINE M. KAISER ◽  
HINRICH KAISER ◽  
MARK O’SHEA
Keyword(s):  
New Guinea ◽  
Molecular Data ◽  
The Philippines ◽  
Morphological Data ◽  
Valid Species ◽  
Museum Specimens ◽  
Type Specimens ◽  
History Of ◽  
Original Species ◽  
Species Specific

Since its conceptualization in 1854, 29 species of the colubrid genus Stegonotus have been recognized or described, of which 15 (admiraltiensis, batjanensis, borneensis, cucullatus, derooijae, diehli, florensis, guentheri, iridis, heterurus, melanolabiatus, modestus, muelleri, parvus, poechi) are still considered valid today. Original species descriptions for the members of this genus were published in Dutch, English, French, German, and Italian and, perhaps as a consequence of these polyglot origins, there has been a considerable amount of confusion over which species names should be applied to which populations of Stegonotus throughout its range across Borneo, the Philippines, Wallacea, New Guinea, Australia, and associated archipelagos. In addition, the terminology used to notate characteristics in the descriptions of these forms was not uniform and may have added to the taxonomic confusion. In this paper, we trace in detail the history of the type specimens, the species, and the synonyms currently associated with the genus Stegonotus and provide a basic, species-specific listing of their characteristics, derived from our examination of over 1500 museum specimens. Based on our data, we are able to limit the distribution of S. modestus to the islands of Ambon, Buru, and Seram in the central Moluccas of Indonesian Wallacea. We correct the type locality of S. cucullatus to the Manokwari area on the Bird’s Head Peninsula of West Papua, Indonesian New Guinea and designate a neotype for S. parvus, a species likely to be a regional endemic in the Schouten Archipelago of Cenderawasih Bay (formerly Geelvink Bay), Indonesian New Guinea. We unequivocally identify and explain the problematic localities of the type specimens of S. muelleri and Lycodon muelleri, which currently reside in the same specimen jar. We remove L. aruensis and L. lividum from the synonymy of S. modestus and recognize them as S. aruensis n. comb. and S. lividus n. comb., respectively. We remove S. keyensis and Zamenophis australis from the synonymy of S. cucullatus and recognize them as S. keyensis n. comb. and S. australis n. comb., respectively. We further remove S. reticulatus from the synonymy of S. cucullatus, S. dorsalis from the synonymy of S. diehli, and S. sutteri from the synonymy of S. florensis. We designate lectotypes for S. guentheri, S. heterurus, S. lividus, and S. reticulatus. Lastly, we introduce S. poechi, a valid species not mentioned in the scientific literature since its description in 1924. This brings the diversity in the genus Stegonotus to 22 species. We also caution that in a complex group of organisms like Stegonotus any rush to taxonomic judgment on the basis of molecular and incomplete morphological data sets may perpetuate errors and introduce incongruities. Only through the careful work of connecting type material with museum specimens and molecular data can the taxonomy and nomenclature of complex taxa be stabilized. 

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