Các nhà khoa học lần đầu tiên ghi nhận trường hợp một con cá sấu "trinh sản". Cá sấu cái sống cô lập suốt 16 năm liền được phát hiện cùng với ổ trứng, hé lộ nguồn gốc tiến hóa của hành vi sinh sản này.

Con cá sấu Mỹ (Crocodylus acutus) bị bắt năm 2 tuổi và sống trong khu chuồng ở công viên bò sát Parque Reptilandia tại Costa Rica. Nó ở đó một mình suốt 16 năm tiếp theo. Tuy nhiên, vào tháng 1/2018, nhà chức trách tìm thấy ổ trứng 14 quả trong chuồng.

Trinh sản là một dạng sinh sản vô tính ở những loài có thể sinh sản hữu tính bình thường. Giới khoa học ghi nhận sinh sản vô tính ở chim, cá mập, thằn lằn và rắn nuôi nhốt cùng nhiều loài khác. Nhưng trước đây, họ chưa từng gặp hành vi như vậy ở họ cá sấu, bao gồm cá sấu thường, cá sấu mõm ngắn, cá sấu caiman và cá sấu sông Hằng.

Trong nghiên cứu công bố hôm 7/6 trên tạp chí Biology Letters, nhóm tác giả cho biết 7 trong số 14 quả trứng do con cá sấu ở Costa Rica đẻ có thể nở được. Nhân viên vườn thú ấp những quả trứng này nhưng chúng không nở. Họ mở số trứng đó. Thành phần bên trong 6 quả trứng không thể quan sát rõ, nhưng quả trứng còn lại chứa phôi thai đã thành hình đầy đủ. Phân tích di truyền cho thấy nó gần như giống hệt con mẹ.

Nhóm nghiên cứu đứng đầu là Warren Booth, nhà côn trùng học ở Viện Công nghệ Virginia, cho biết họ hơi thất vọng khi quả trứng không thể nở được. Dù vậy, không hiếm gặp con non sinh theo cách này bị dị tật và không thể phát triển. Theo họ, trinh sản có thể phổ biến hơn ở những loài có nguy cơ tuyệt chủng.

Phát hiện trinh sản ở cá sấu có nghĩa hình thức sinh sản này có ở cả chim, hậu duệ của khủng long và cá sấu, chứng tỏ nguồn gốc tiến hóa chung. Chim và cá sấu là đại diện còn sót lại của thằn lằn chúa, nhóm động vật bao gồm cả khủng long và thằn lằn bay.

(https://vnexpress.net/lan-dau-phat-hien-ca-sau-trinh-san-4614484.html,n.d.)

Scientists have recorded the first case of a "virgin birth" in a crocodile. A female crocodile that lived in isolation for 16 years was found with a clutch of eggs, shedding light on the evolutionary origins of this reproductive behavior. The American crocodile (Crocodylus acutus) was captured at the age of 2 and lived alone in a cage at the Reptilandia reptile park in Costa Rica for the following 16 years. However, in January 2018, authorities discovered a nest of 14 eggs in the enclosure.

The virgin birth is a form of asexual reproduction found in species that can also reproduce sexually. Scientific records have documented asexual reproduction in birds, sharks, lizards, and snakes kept in captivity, among many other species. However, such behavior had never been observed in crocodilians, which include common crocodiles, alligators, caimans, and gharials.

In a study published on June 7 in the journal Biology Letters, the research team reported that 7 out of the 14 eggs laid by the crocodile in Costa Rica were viable. Zoo staff incubated these eggs, but they did not hatch. Upon opening the eggs, they found that while the contents of 6 eggs were not clearly observable, one egg contained a fully formed embryo. Genetic analysis revealed that it was nearly identical to its mother.

The research team, led by Warren Booth, an entomologist at Virginia Tech, expressed some disappointment that the egg did not hatch. Nonetheless, it is not uncommon for offspring produced this way to have deformities and be unable to develop properly. They suggest that virgin birth may be more common in endangered species.

The discovery of virgin birth in crocodiles indicates that this reproductive method exists in both birds, the descendants of dinosaurs, and crocodiles, demonstrating a shared evolutionary origin. Birds and crocodiles are the last remaining representatives of archosaurs, a group of animals that includes dinosaurs and flying reptiles.

The first discovery of a Parthenogenesis in crocodile

Scientists have documented the first case of a crocodile reproducing asexually. A female crocodile, isolated for 16 years, was found with a nest of eggs, shedding light on the evolutionary origins of this reproductive behavior. The American crocodile (Crocodylus acutus) was captured at the age of two and housed in an enclosure at Parque Reptilandia, a reptile park in Costa Rica. It remained solitary for the following 16 years. However, in January 2018, officials discovered a clutch of 14 eggs in its enclosure.

Virgin birth is a form of asexual reproduction in species that can normally reproduce sexually. Scientists have previously documented asexual reproduction in captive birds, sharks, lizards, and snakes, as well as many other species. However, they had never encountered such behavior in the crocodile family, including common crocodiles, dwarf crocodiles, caimans, and the Gharial.

In a study published on June 7 in the journal Biology Letters, the authors reported that seven of the 14 eggs laid by the Costa Rican crocodile were viable. Zoo staff incubated the eggs, but they failed to hatch. The eggs were opened, and while the contents of six eggs were unclear, the remaining egg contained a fully formed embryo. Genetic analysis revealed that it was nearly identical to the mother.

Warren Booth, an entomologist at the Virginia Tech Institute and the study's lead author, expressed slight disappointment that the egg did not hatch. However, it is not uncommon for offspring produced in this manner to have birth defects and be unable to develop. According to the researchers, virgin birth may be more common in endangered species.

The discovery of virgin birth in crocodiles suggests that this reproductive mode is present in both birds and crocodiles, descendants of dinosaurs, indicating a shared evolutionary origin. Birds and crocodiles are the remaining representatives of archosaurs, a group of animals that includes dinosaurs and pterosaurs.

Scientists have for the first time recorded a case of a crocodile after "parthenogenesis." A female crocodile, isolated for 16 years, was discovered with a clutch of eggs, shedding light on the evolutionary origin of this reproductive behavior. The American crocodile (Crocodylus acutus) was captured at the age of two and lived in an enclosure at Parque Reptilandia in Costa Rica. It remained alone for the next 16 years. However, in January 2018, authorities found a clutch of 14 eggs in the enclosure.

Parthenogenesis is a form of asexual reproduction in species that typically reproduce sexually. Scientists have documented parthenogenesis in birds, sharks, lizards, and snakes in captivity, among many other species. However, they had never encountered such behavior in crocodilians, which include true crocodiles, alligators, caimans, and gharials.

In a study published on June 7 in the journal Biology Letters, the authors noted that 7 of the 14 eggs laid by the Costa Rican crocodile were potentially viable. Zoo staff incubated the eggs, but none hatched. They later examined the eggs. The contents of six were unclear, but one contained a fully developed embryo. Genetic analysis showed it was almost identical to the mother.

The research team, led by Warren Booth, an entomologist at Virginia Tech, said they were slightly disappointed that the egg did not hatch. However, it is not uncommon for offspring produced this way to have deformities and be unable to develop. According to them, parthenogenesis may be more common in species at risk of extinction.

The discovery of parthenogenesis in crocodiles suggests that this form of reproduction exists in both birds and crocodiles, the descendants of dinosaurs, indicating a shared evolutionary origin. Birds and crocodiles are the last surviving representatives of archosaurs, a group of animals that includes both dinosaurs and flying reptiles.