Many reptiles lay eggs, a process called oviparous. But some, like the New Mexico whiptail lizard, reproduce asexually using a process called parthenogenesis.
These asexual offspring are clones of the mother and are therefore genetically similar. This allows the mother to produce offspring without wasting her limited ectotherm energy on searching for and mating with males.게코도마뱀
Most reptiles reproduce sexually, which means the male and female of a species must fertilize each other’s eggs for embryonic development to take place. However, there are also reptiles—such as the crocodile and a few gecko species (including the Bynoe gecko and Komodo dragon)—that can reproduce asexually, producing offspring that are genetically identical to their parents.
Male and female reptiles have special reproductive structures that help in fertilization. In males, these are the testicles, which are housed internally. In females, these are the oviducts, which lack a true uterus and instead have paired openings that connect to each other in the abdominal cavity (called the cloaca).
During mating, the male reptile will either use a single penis (turtles and crocodile) or two hemipenes 게코도마뱀 to deliver sperm into the cloaca of the female. A genital courtship is usually involved before actual copulation takes place, and in some reptiles—such as the diamondback terrapin (Malaclemys terrapin) and some snakes—the male’s sperm can be stored in the female’s cloaca for up to six years, which allows for fertilization of subsequent clutches without further contact by the male.
To prepare for fertilization, the ovary secretes a protein called fertilin into the cloaca. This protein binds to integrins in the egg plasma membrane, which helps the sperm fuse with the eggs’ DNA to form fertilized eggs.
Reptiles are an interesting group of creatures that can be found in a wide variety of shapes, sizes and colors. They range from tiny lizards to huge dinosaurs and have evolved different reproductive strategies to ensure survival in their diverse environments. Some reptiles lay eggs while others give birth to live young, and a few species even reproduce asexually.
Most reptiles reproduce sexually and with internal fertilization. Males have one or two penises, also known as hemipenes, which are visible on the outside of the body as two bulges behind the cloaca towards the tail. These organs are separate from the urinary tract and are only used for reproduction. The sperm is passed from the cloaca to the oviducts in the female’s body, and fertilization takes place.
After fertilization, the ovary is sealed off and development takes place inside. When the egg is ready to be laid, it is released from the oviduct through an opening adjacent to each ovary. Depending on the species, copulation may occur before or during ovulation, or it can take months to complete development of the eggs and their ovulation.
Some reptiles laying eggs are called oviparous while those that give birth to live young are known as viviparous. Oviparous reptiles are usually characterized by their ability to lay eggs that can survive in dry, terrestrial habitats. The eggs have a shell that protects them and contain amniotic fluid that provides nutrients and moisture. Male reptiles can be sexed by the presence of the hemipenes or by secondary sexual features like size, proportions and head shape, such as in male Jackson’s chameleons that have three prominent horns.
Reproduction in Captivity
Many captive reptiles, especially those used in zoological collections and conservation programs, are bred in captivity. However, little attention has been given to the impacts of inbreeding on captive reptile populations. In fact, inbreeding in a captive reptile population can result in genetic defects such as kinked spines (in Spider Royal Pythons) and reduced growth rates (in Tiger Heliconians). It may also contribute to poor reproduction, particularly in oviparous species.
Mating between a male and female reptile is triggered when both partners produce hormones that make them sexually receptive. Males usually mount the female, inserting their reproductive organ into her body cavity. After a period of courtship, sperm are released and fertilize her eggs. In viviparous reptiles, such as snakes and turtles, the fertilized eggs are carried by the female until they hatch.
A cloaca is an opening where waste and sperm are excreted, and from it, sperm enter each ovary through an oviduct. The eggs are laid in a nest built by the parent, and the number of eggs varies by species. After the eggs hatch, the fetus develops inside a hard, leathery shell.
Ovulation and embryo development are influenced by temperature, food availability, maternal care, stress, and other environmental factors. A lack of adequate nutrition during gestation can cause fetal abnormalities, including hypoglycemia and hypercalcemia. During this stage, the fetus relies on the yolk of the egg for nutrients.
While the majority of reptiles lay eggs, a few species give birth to live young. This is known as viviparity.
The majority of snakes and lizards that lay eggs are oviparous, meaning they produce eggs to be incubated by their females. To reproduce, a male reptile either uses his single penis (in the case of turtles and crocodiles) or one of two hemipenes to discharge sperm into the cloaca of a female reptile. The sperm may then fertilize the eggs or be stored for up to 6 years until fertilized by another sperm.
During this process, the egg shell is deposited and the embryo develops within extra membranes called an amnion and an allantois, which serve to protect the embryo from excessive water loss during incubation. The embryo also develops a rich yolk source, which provides the energy it needs to grow and hatch.
In contrast, a few species of snakes and lizards that give birth to live young are ovoviparous, which means the embryo is housed internally in a sac. This allows the female to control the temperature, nutrient intake and movement of the embryo, and can minimize the risk of obstetric complications. These reptiles include bearded dragons, blue-tongued skinks and many geckos. Interestingly, this type of reproduction evolved later than egg-laying. Researchers believe it’s likely the result of lifestyle and environmental changes.