User:Emw3181/Amplexus
Draft for Amplexus edit
Introduction:
Amplexus (Latin "embrace") is a type of mating behaviour exhibited by some externally fertilizing species (chiefly amphibians and horseshoe crabs) in which a male grasps a female with his front legs as part of the mating process, and at the same time or with some time delay, he fertilizes the eggs as they are released from the female's body.[1] In amphibians, females may be grasped by the head, waist, or armpits, and the type of amplexus is characteristic of some taxonomic groups. Amplexus involves direct contact between male and female, distinguished from other forms of external fertilization such as broadcast spawning, where sperm and eggs are freely shed into water without direct contact by individuals. This amplexus behaviour allows the amphibians cloacae to be in close contact while gametes are being released.[2]Additionally, amplexus is thought to help with the alignment of the reproductive tracts of both males and females which furthermore contributes to the achievement of successful fertilization.[1] The duration of amplexus has been found to vary across different species as in some species it has been found to last for many days but in other species, it has been found to last a few hours.[3] Despite the variation in the duration of amplexus across different species, typically all the species that exhibit this behaviour have to use their forelimb muscles for the whole duration of amplexus.[3]These forelimb muscles that are used during amplexus are typically larger in males than females.[3] Interestingly, in addition to those forelimb muscles being larger in males, male frogs also typically have keratin pads which are located on their thumbs and contribute to the success of amplexus by assisting in gripping the female for the duration of amplexus.[4] In order for amplexus to be initiated male frogs must first find a mate by attracting one through calls, typically in the evening.[3] Once a male has successfully attracted a mate the process of amplexus begins while the unsuccessful males are forced to continue their search for a mate through further calls.[3] The hormone arginine vasotocin (AVT) has been identified as having an effect on the calling behaviours produced by these male amphibians when searching for a female mate, as AVT increased the amount of calling behaviour produced in male amphibians.[2] Additionally, it is believed that the gonadotropin-releasing hormone (GnRH) has an influence on amplexus in amphibians as it has been found to produce or initiate this behaviour in many anuran amphibians.[2] Furthermore, both arginine vasotocin and gonadotropin-releasing hormone have been found to be involved in the sexual behaviour of male amphibians.[2]
There are two different types of amplexus known as inguinal and axillary amplexus.[5] These two types of amplexus have been classified based on the position of the male amphibian to the female it is mating with.[5] When a male amphibian clasps a female around their waist (inguinal region) using his forelimbs, this is then considered inguinal amplexus.[5] Contrastingly, when a male amphibian clasps behind the forelimbs (axillary region) of a female amphibian, this is then considered axillary amplexus.[5]
- ^ a b Mollov, Ivelin; Popgeorgiev, Georgi; Naumov, Borislav; Tzankov, Nikolay; Stoyanov, Andrei (2010). "Cases of abnormal amplexus in anurans (Amphibia: Anura) from Bulgaria and Greece" (PDF). Biharean Biologist.
- ^ a b c d Propper, Catherine R.; Dixon, Timothy B. (1997). "Differential Effects of Arginine Vasotocin and Gonadotropin-Releasing Hormone on Sexual Behaviors in an Anuran Amphibian". Hormones and Behavior. 32 (2): 99–104. doi:10.1006/hbeh.1997.1408.
- ^ a b c d e McLister, James (2003). "The metabolic cost of amplexus in the grey tree frog (Hyla versicolor): assessing the energetics of male mating success". NRC Canada. doi:10.1139/Z03-013.
- ^ O’Rourke, Dorcas P.; Rosenbaum, Matthew D. (2015), "Biology and Diseases of Amphibians", Laboratory Animal Medicine, Elsevier, pp. 931–965, ISBN 9780124095274, retrieved 2019-10-24
- ^ a b c d Nussbaum, Ronald A. (1980). "Phylogenetic Implications of Amplectic Behavior in Sooglossid Frogs". Herpetologica. 36 (1): 1–5. ISSN 0018-0831.