User:Jmt39/California red-sided garter snake

Article Outline
A brief introduction of the species and related subspecies.

Appearance
General morphology of red-sided garter snakes.

Habitat
Brief description of habitat (dens during winter hibernation and mossy area in summer) and geographical distribution (Northern America and Southern Canada).

Feeding habits
Feeds on earthworms and frogs. Only feeds in summer.

Reproduction
- General reproduction information - mating system, breeding season, gestation, etc

- Reproductive anatomy (hemipenes, ovaries, cloaca, renal sex segment, etc) and functions of these organs.

Pre-copulatory behavior
- Spring emergence and formation of mating balls.

- Courtship tactics - tongue flicking, pheromonal cues, male- male combat, and other mating behaviors.

- Mate preference - unmated females, large body size and longer snout length for both males and females

- Effects of temperature on copulation and related hormones (testosterone, melatonin, corticosteroid, etc.)

Post-copulatory behavior
- Females leaving the mating balls immediately after mating.

- Sperm competition - cleaning female reproductive tract and altering pheromonal cues.

- Mate guarding by copulatory plug.

Sexual Conflict
- Copulation duration: females and males prefer different lengths of time for mating.

- Presence of copulatory plug and injury to female reproductive tract.

Article Draft
Thamnophis sirtalis parietalis, commonly known as red-sided garter snake, is a subspecies of Common garter snakes (Thamnophis sirtalis) in the subfamily Natricinae of the family Colubridae. (14) This subspecies is widely spread across Northern America and Southern Canada. (3) Due to the extremely cold climate in the areas, these snakes are in hibernation for about 8 months a year. (5) During spring and summer, T.s.parietalis mates, migrates, feeds, gestates, gives birth to their young ones, and returns to their dens for hibernation before fall begins. (3) The snakes of this subspecies are not dangerous as they are mainly non-venomous. (17) The red-sided garter snakes can be distinguished from other species due to the red, yellow and black patterns on their body. (14)

Appearance
The red-sided garter snakes have an upper row of well-defined red spots and a lower row has patches of red color that smear on the dark area on either side of their back. (14) These snakes have multiple yellow stripes present on their body. Thamnophis sirtalis parietalis are sexually dimorphic, where females are usually larger than the males. (3) The females can range from 18 to 24 inches in length, whereas males can grow up to 12 to 18 inches. (3)

Phenology and Habitat Use
Red-sided garter snakes are mainly seen in plain areas of the central and northern parts of America, along with southern and western Canada. (11) In some of these areas, winter temperatures are very harsh and sometimes even drop below zero. Due to the climate, hibernation is essential for the survival of these snakes. (11) During winter, these snakes commonly take shelter in the underground dens in large groups to hibernate and protect themselves from cold weather and predators. (11) As soon as the temperature rises, the snakes emerge from their dens in spring. (3) Since food or water is not available close to dens, the snakes migrate to feeding grounds after mating. (3) In summer, the snakes move to mossy or marshy areas where they look for food. (11) The adult red-sided garter snakes feed only for 2 to 3 months during summer, whereas the young ones feed till the start of winter. (14) The adult snakes primarily feed on ranid and wood frogs, but they might occasionally feed on mice and voles. (11) (14) The young snakes mostly feed on earthworms. (14) Soon after feeding, close to the end of summer, the adult snakes return to their dens for winter hibernation. (3) The young snakes, around one-year-old, spend more time in marshy areas to find as much food as possible before the winter temperatures arrive. (11) These young snakes also hibernate in marshy areas as their small size makes them less visible to predators. (11) During winter hibernation, the energy stored from summer feeding is used for body growth and maintenance to survive for months in subzero temperatures. (13)

Reproduction
In red-sided garter snakes, the breeding season usually begins in early spring and lasts for about a month. (5) These snakes exhibit a polygynous mating system, which means that male T. s. parietalis mates with multiple females during the mating season. (1) During the mating season, male snakes form a mating ball near the dens and court females as they emerge. (3) Each female is courted by hundreds of males upon emergence. (2)(3) After mating, males and females move to mossy summer grounds where they find food and water and birth the offspring. (11) These snakes are viviparous and can birth about 30 young ones in one mating season. (3) Gestation period is about 3 to 4 months, and the young ones reach sexual maturity at 1.5 or 2 years of life. (11) In this species, the offspring are usually born before the adults re-enter winter dormancy, and immediately after birth, adult male and female snakes migrate back to their dens and re-enter hibernation in early fall before the temperature falls. (3)(11)

The reproductive system of male red-sided garter snakes includes testicles, epididymis, vas deferens, hemipenes, and renal sex segment. Testes produce sperm that are transported by epididymis to the vas deferens, which then transfer the sperm to hemipenes. These snakes have a double penis with one testis supplying seminal fluid to each hemipenis. Hemipenes are saclike organs that facilitate sperm transfer to the female. During winter, the segment of the vas deferens is used for sperm storage. (3) The function of the renal sex segment, a segment from kidney, is to produce copulatory pheromones and the granules for formation of a copulatory plug. (15) (3) The female reproductive system of red-sided garter snakes consists of ovaries, an oviduct, and a cloaca. The ovaries and oviducts are long due to the streamlined body of the snake. Multiple follicles(eggs) are present on the elongated ovaries. After mating, it takes up to 6 weeks for sperm to travel through the oviduct and reach the developing follicles in the ovaries. (3)

Pre-copulatory behavior
The behavior and physiology of red-sided garter snakes is heavily influenced by seasonal changes in the environment. (2) Temperature is one of the most crucial factors in regulating the life cycle of this species. (9) During low temperatures in fall and winter, tens of thousands of male and female red-sided garter snakes hibernate together, in a shared underground communal den, for about eight months each year. (10)(9) When the temperature rises around 25°C, it leads to the emergence of these snakes from their dens and triggers mating behavior. (12)(3) During mating season, males emerge first, all together in big groups, whereas females emerge singly or in small groups around 1 to 3 weeks after the emergence of males. (2)(9) When females start to emerge, males begin to “mating balls '' where they gather around at the opening of the communal dens and start courting the females as soon as they emerge from dormancy. (3) The courtship from males can continue from minutes to hours, but due to vigorous courting from males, females typically mate within 30 minutes after emerging. (1)(3)

Along with behavioral change, physiological and hormonal changes also arise with the variation in temperature. Male and female garter snakes exhibit seasonal hormone patterns. (5) In this species, corticosterone levels are high, and melatonin levels are low during winter hibernation. (12) Melatonin and corticosterone are crucial in regulating temperature-induced functions for reproduction, such as initiating emergence, maintaining the hibernation cycle, triggering gametogenesis, and other reproductive behavior. (12) During spring emergence, the testis of male T. s. parietalis are still regressed, and the level of sex steroid hormones is still low due to the long winter dormancy. (5) Testis regression peaks during summer. During winter, testosterone levels are low. After hibernation, when the temperature rises, testosterone levels start to increase gradually to prepare for summer gametogenesis. (5) However, testosterone levels do not influence male mating behavior. (5) Even though testosterone levels are highest in summer, courtship behavior in male red-sided garter snakes is maximal during spring as the females are most receptive immediately after hibernation. (5) Along with testosterone, some other hormones that play an essential role in converting androgens to testosterone, also peak during summer. (5) Whereas some reproductive hormones like StAR, which is responsible for importing sex steroid hormones, peak around spring emergence. (5)

In female T. s. parietalis, the hormone cycle frequently fluctuates due to seasonal changes. (2) Estrogen level decreases during winter dormancy, but the amount of estrogen rapidly increases after copulation and reduces again during follicular development in summer. (2)(5) Similarly, estradiol is produced the highest during the peak breeding season, especially immediately after mating. (5) The primary function of estradiol is to activate the transport of newly deposited sperm and to transport the sperm stored from the previous mating season to the oviduct. (1) E2 synthesis is the process that synthesizes estrogen and peaks approximately 6 hours after mating and returns to normal within 24 hours of copulation. (5) E2 synthesis also play an important role in regulating female reproductive functions such as vitellogenesis, receptivity, attractiveness, and pheromone production. (5) As red-sided garter snakes undergo gametogenesis after copulation, ovulation usually occurs about 6 to 8 weeks after mating. (2) However, copulation does not influence or prompt ovulation. (2)

Post-copulatory behavior
During copulation, male snakes usually deposit a copulatory plug in the female cloaca, which induces sperm competition among males. (1) These snakes deposit a thick translucent gelatinous plug that seals the female cloaca by attaching the gelatinous substance to the cloacal wall. (2)(15) The primary function of mating plug production is to prevent the females from remating. (15) Immediately after mating, female T. s. parietalis attempts to rapidly disperse from the mating ball to avoid any injury or suffocation due to large masses of males. (8) The mating plug maintains a reproductive barrier for roughly 72 hours or more after mating. (15) However, during this time, females either become unreceptive or move away from the mating grounds. (15) Female red-sided garter snakes start migrating toward the summer feeding areas, but males stay at the communal den openings till the end of the breeding season. (3)

Along with mate guarding the females, mating plugs also play an important role in sperm transport, removing previously stored sperm and acting as antiaphrodisiacs in females. (1)(17)  The formation of a copulatory plug initiates the transfer of recently deposited sperm and evacuates stored sperm in the female oviduct from the prior mating season due to the circulating estradiol in the female reproductive system stimulated by copulation. (1) The plug is also essential for male reproductive success as it helps by blocking the female cloacal opening and preventing leakage of the deposited sperm. (17) Alteration in female pheromones is chiefly associated with seminal fluid rather than the presence of a copulatory plug. (15)During sperm transfer, the seminal fluid and plug granules ejaculated in the female oviduct contain compounds that can affect a female’s sexual attractiveness and receptivity. (15) After a female copulates, her attractiveness and receptivity decrease due to the changes in pheromonal cues that determine a female’s attractiveness. (15) These pheromonal trials indicate the mating status of a female. (6) These trails can be recognized by males from miles away. (6) Due to the presence of altered pheromonal trails of females, fewer males court these females and prevent remating as they want to minimize the time spent on the females who are not receptive. (15) After copulation, the presence of copulatory pheromone mainly reduces the chances of female remating rather than a change in sex-attractiveness hormone. (6) The duration of the release of copulatory pheromones coincides with the duration of a copulatory plug. (6)

In Thamnophis sirtalis parietalis, sperm competition among males also increases due to females' ability to use stored sperm from prior season for reproduction. (16)

Sexual Conflict
Male–male competition in red-sided garter snakes is manifested in ‘tail wrestling’ rather than body-combat, and males constantly push their tails in between a female and any other courting male. (4) Sexual conflict over mating is a prominent feature of the mating system of red-sided garter snakes. When the female is ready to mate, she gapes her cloaca so copulation can occur. Females prefer a shorter copulatory period to avoid an injury to herself whereas males prefer longer copulatory period to deposit as much sperm as possible. For males, longer copulatory periods are also important for formation and deposition of copulatory plugs. (6) These plugs often injure the reproductive tract of females so they perform body rolls to stop male from plug deposition and get away from the males. This creates a conflict on preferred copulatory periods between males and females which leads to sexual conflict. (8) Females also leave the den and go to a secluded area right after mating to avoid attention of other males of the species.