Project

Estratégias reprodutivas no gênero Micrurus (Serpentes, Elapidae) / Reproductive strategies in the genus Micrurus (Serpentes, Elapidae)

Goal: No Brasil existem basicamente duas linhagens de espécies de coral-verdadeira, conforme o padrão de coloração, grupo de anéis pretos padronizados em mônades (BRM) e o grupo de anéis pretos em tríades (BRT). As espécies de cobra coral estão distribuídas em diversos biomas e consequentemente estão expostas a diferentes condições climáticas. Existe a hipótese que em alguns grupos de serpentes ocorra uma forte conservação ancestral das estratégias reprodutivas, mesmo que as espécies deste grupo estejam em regiões climaticamente diferentes. Entretanto, outros trabalhos apontam que as espécies ectotérmicas podem ser fortemente influenciadas pelas condições climáticas, ou seja, estas iriam alterar as condições morfofisiológicas e reprodutivas; conforme as condições ambientais existentes no meio. Desta forma, o propósito deste trabalho é investigar as diferenças nas estratégias reprodutivas existentes no gênero Micrurus, nas linhagens BRM e BRT, comparando espécies distribuídas em diferentes biomas e ao mesmo tempo, próximas filogeneticamente. Para tanto, serão analisados os ciclos reprodutivos de machos e fêmeas, os períodos de ocorrência dos eventos reprodutivos (e.g., espermatogênese, hipertrofia do segmento sexual renal (SSR), vitelogênese, oviposição, padrões de maturidade sexual) e as estratégias reprodutivas existentes em cada espécie. Análises histológicas e histoquímicas serão empregadas para avaliar a existência da estratégia de estocagem dos espermatozoides (machos e fêmeas), o período da espermatogênese, natureza química das secreções do oviduto e do SSR. Averiguando assim, com uma abordagem comparativa, a hipótese da influência climática agir mais intensamente no ciclo reprodutivo nas corais-verdadeiras, ao invés de existir uma conservação das estratégias reprodutivas./

Coral Snakes can be divided into two clades based on the color pattern, black ring arranged in monads (BRM) and black ring in triads (BRT). This species are distributed in several biomes and consequently they are exposed to different climatic conditions. It is hypothesized that in some groups of snakes a strong ancestral conservation of reproductive strategies occurs even though the species of this group are in climatically different regions. However, other studies indicate that the ectothermic species can be strongly influenced by the climatic conditions, that is, they would alter the morphophysiological and reproductive period, according to environmental conditions in the field. In this way, the purpose of this work is to investigate the differences in the reproductive strategies existing in the genus Micrurus, in the BRM and BRT clades, comparing species distributed in different biomes. We will analyze the reproductive cycles, the occurrence of periods of reproductive events (e.g., spermatogenesis, sexual renal hypertrophy segment (SSK), vitelogenesis, oviposition patterns of sexual maturity), and reproductive strategies existing in each species. Histological and histochemical techniques will be used to evaluate the existence of the strategy of sperm storage (males and females), the period of spermatogenesis, histochemical nature of oviduct and SSR secretions. Thus, with a comparative approach, the hypothesis of climatic influence acts more intensely on the reproductive cycle in true corals, rather than on the conservation of reproductive strategies

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Erick Augusto Bassi
added 2 research items
We analyzed the hypothesis that the lack of synchronization between the mating and ovulation period of Micrurus frontalis (BRT clade) is indicative of the capacity of females to store sperm. Conversely, since these reproductive events occur in the same season for Micrurus corallinus (BRM clade), sperm storage is not expected. Thus, we analyzed the reproductive cycle of female M. corallinus and M. frontalis , and investigated the occurrence of sperm storage. Our results showed that these two species of coral snakes (clades BRM and BRT) possess different reproductive cycles. Micrurus frontalis exhibits an extensive reproductive period encompassing three seasons (summer, autumn and winter), while M. corallinus directs secondary vitellogenesis and ovulation to the hottest period of the year (spring and summer). We confirm, for the first time, the strategy of sperm storage (SSr) in females of the genus Micrurus . We observed sperm storage receptacles located in the non-glandular uterus in all seasons of the year for M. corallinus and in spring, summer and autumn in M. frontalis . Furthermore, the presence of SSr in females in the non-reproductive (post-ovulatory) period, the verification of myoid cells around the receptacles and secretion of neutral carbohydrates in the lumina of SSrs may indicates a long-term storage. The posterior infundibulum is another possible region of sperm storage by the presence of tubular ciliated gland; however, reproductive studies with other species of the genus are necessary for a better understanding of the reproductive strategies of the BRT and BRM clades.
The processes of follicular development, ovulation, egg capture, and egg transport vary among vertebrates. Therefore, analysis of the reproductive tract of several lineages is needed for understanding the evolutionary changes of the reproductive system. In turtles, the ovulated eggs are released into the coelomic cavity and taken up by one of the two oviducts, a phenomenon called extrauterine migration of eggs. However, the process of egg uptake in lizards is different. The egg is ovulated directly into the infundibulum, and oocyte uptake by the contralateral oviduct rarely occurs. The same pattern has been hypothesized to occur in snakes. To test this hypothesis, we analyzed the reproductive tract of female Micrurus corallinus preserved in zoological collections. We examined the anatomical characteristics of the infundibulum and ovary and compared the reproductive output between the ovaries to verify the mechanism of egg capture and the anatomical viability of extrauterine migration of eggs. The reproductive output of the right ovary was higher than that of the left ovary, and the higher number of eggs in the right oviduct is due exclusively to the production of the ipsilateral ovary. Several anatomical features prevent extrauterine migration of eggs, including the asymmetry of the reproductive system, the arrangement of the ovarian follicles in a single row, and the formation of a wrapping around the ovary and infundibulum by the visceral pleuroperitoneum membrane (preventing against ectopic eggs). Therefore, the hypothesis of egg capture by the contralateral oviduct is anatomically infeasible in M. corallinus and possibly in other snakes. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.
Erick Augusto Bassi
added a project goal
No Brasil existem basicamente duas linhagens de espécies de coral-verdadeira, conforme o padrão de coloração, grupo de anéis pretos padronizados em mônades (BRM) e o grupo de anéis pretos em tríades (BRT). As espécies de cobra coral estão distribuídas em diversos biomas e consequentemente estão expostas a diferentes condições climáticas. Existe a hipótese que em alguns grupos de serpentes ocorra uma forte conservação ancestral das estratégias reprodutivas, mesmo que as espécies deste grupo estejam em regiões climaticamente diferentes. Entretanto, outros trabalhos apontam que as espécies ectotérmicas podem ser fortemente influenciadas pelas condições climáticas, ou seja, estas iriam alterar as condições morfofisiológicas e reprodutivas; conforme as condições ambientais existentes no meio. Desta forma, o propósito deste trabalho é investigar as diferenças nas estratégias reprodutivas existentes no gênero Micrurus, nas linhagens BRM e BRT, comparando espécies distribuídas em diferentes biomas e ao mesmo tempo, próximas filogeneticamente. Para tanto, serão analisados os ciclos reprodutivos de machos e fêmeas, os períodos de ocorrência dos eventos reprodutivos (e.g., espermatogênese, hipertrofia do segmento sexual renal (SSR), vitelogênese, oviposição, padrões de maturidade sexual) e as estratégias reprodutivas existentes em cada espécie. Análises histológicas e histoquímicas serão empregadas para avaliar a existência da estratégia de estocagem dos espermatozoides (machos e fêmeas), o período da espermatogênese, natureza química das secreções do oviduto e do SSR. Averiguando assim, com uma abordagem comparativa, a hipótese da influência climática agir mais intensamente no ciclo reprodutivo nas corais-verdadeiras, ao invés de existir uma conservação das estratégias reprodutivas./
Coral Snakes can be divided into two clades based on the color pattern, black ring arranged in monads (BRM) and black ring in triads (BRT). This species are distributed in several biomes and consequently they are exposed to different climatic conditions. It is hypothesized that in some groups of snakes a strong ancestral conservation of reproductive strategies occurs even though the species of this group are in climatically different regions. However, other studies indicate that the ectothermic species can be strongly influenced by the climatic conditions, that is, they would alter the morphophysiological and reproductive period, according to environmental conditions in the field. In this way, the purpose of this work is to investigate the differences in the reproductive strategies existing in the genus Micrurus, in the BRM and BRT clades, comparing species distributed in different biomes. We will analyze the reproductive cycles, the occurrence of periods of reproductive events (e.g., spermatogenesis, sexual renal hypertrophy segment (SSK), vitelogenesis, oviposition patterns of sexual maturity), and reproductive strategies existing in each species. Histological and histochemical techniques will be used to evaluate the existence of the strategy of sperm storage (males and females), the period of spermatogenesis, histochemical nature of oviduct and SSR secretions. Thus, with a comparative approach, the hypothesis of climatic influence acts more intensely on the reproductive cycle in true corals, rather than on the conservation of reproductive strategies