Toxicofera

Toxicofera is a clade of squamate reptiles that includes all venomous reptiles and their closest relatives. This group encompasses a wide variety of species, including all snakes and certain lizard families such as monitor lizards, Gila monsters, and iguanas. The name "Toxicofera" means "those who bear toxins," reflecting the presence of venom in many of its members.

Overview

The concept of Toxicofera was first proposed in 2003 by researchers who used molecular phylogenetic studies to demonstrate that venomous capabilities evolved once in the common ancestor of this group. This finding was significant because it suggested that venom evolved only once in squamates, rather than multiple times independently.

Evolutionary Significance

The evolutionary significance of Toxicofera lies in its unified origin of venom. Venom is a complex trait that involves the production of toxic proteins used for predation and defense. The presence of venom in Toxicofera members is believed to have provided evolutionary advantages, such as improved prey capture and deterrence of predators.

Venom Composition

Venom in Toxicofera is composed of a variety of proteins and enzymes, each with specific functions. These can include:

• Neurotoxins - Affect the nervous system, causing paralysis.
• Hemotoxins - Disrupt blood clotting and damage tissues.
• Cytotoxins - Destroy cells, leading to tissue necrosis.

The composition of venom can vary significantly between species, reflecting adaptations to different ecological niches and prey types.

Phylogenetic Relationships

Toxicofera is divided into three main subgroups:

• Serpentes: This group includes all snakes, which are entirely carnivorous and many of which are venomous.
• Anguimorpha: This includes families such as Varanidae (monitor lizards) and Helodermatidae (Gila monsters), both of which have venomous members.
• Iguania: While most iguanas are not venomous, some species have been found to possess venom glands, although their venom is not harmful to humans.

Research and Implications

Research into Toxicofera has implications for understanding the evolution of venom and its role in ecological interactions. It also has potential applications in medicine, as venom components can be used to develop new drugs and treatments.

Also see

• Squamata
• Venom
• Reptile
• Evolution of venom

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