Are Frogs Asexual?

I hold a Bachelors of Science in Fisheries and Wildlife, and a certificate in Master Herpetology and have learned about frog and toad species during my studies for school.

I think that reptiles and amphibians have such interesting ways of mating and breeding. 

Frogs reproduce sexually involving the gametes from males and females to produce viable eggs. Therefore, frogs are not asexual requiring a male and female to fertilize eggs during mating.

This article will discuss the mating and reproduction of frogs. We will define asexual and sexual reproduction and internal and external fertilization.

Frogs have an interesting way of mating and can become complex in where they deposit their eggs because of this.

Males participate in different behaviors to help them gain access to a female during mating. 

What is Asexual Reproduction? 

Asexual reproduction does not involve a male counterpart to deposit sperm to the eggs produced by the female. It is producing offspring without fertilization from a mate. The female produces offspring solely using her own genetics. 

Parthenogenesis is an asexual reproductive mode seen in salamanders.

This is essentially cloning the female by producing female offspring without using male gametes.

These offspring are genetically identical to the female since no male was involved. 

Asexual reproduction can surpress gene flow in a population.

No new genetics are being introduced to create the offspring. The female offspring are genetic clones of the mother and only possess her genetics. 

Frogs do not reproduce asexually.

They rely on a mate to fertilize their eggs during sexual reproduction.

There are different methods of sexual reproduction and oviposition and deposition exhibited by frogs to carry out reproduction. 

Frogs Reproduce Using External Fertilization 

Frogs mainly reproduce through sexual reproduction where gametes from a male and a female combine into an embryo.

External fertilization takes place when a sperm meets an egg outside of the female’s body.

The eggs are fertilized as they are laid in order to develop

A female frog will release unfertilized gametes into their deposition site.

Different species may deposit their eggs in differing locations at the breeding site.

Frog larvae require some sort of water to develop, so eggs may be deposited directly in water, on leaves above water, or terrestrially near water. 

Males will gather around females to release sperm over the unfertilized eggs as they are deposited by the female.

Multiple males may parent offspring in a clutch of eggs, or one may try to prevent this by using amplexus.

Either way, frog group spawning can involve many individuals releasing sperm and eggs at once. 

What is Amplexus? 

Amplexus is a term used to describe when male frogs grasp female frogs during mating and reproduction. They grasp them to bring their cloacas closer in the hopes that the male will fertilize the majority of or all of the eggs released from the female.

There are a few types of amplexus:

  • Axillary amplexus occurs when the male grasps the female behind the forelimbs. This is the most common form of amplexus. Males may interlock their thumbs and ward off other males as he claims the female. 
  • Cephalic amplexus allows the male to clasp the female around the head. Inguinal amplexus occurs when the male grasps the female around her waist. This behavior is seen in early frog lineages. 

The three different amplexus behaviors have evolved independently of each other and each species typically displays one over the others.

Amplexus serves to allow the grasping frog to better outcompete other males for fertilization.

Multiple frogs may grasp a female or other males at once and could stay like that for hours. 

Few Frogs Reproduce Using Internal Fertilization 

Some frog species may reproduce internally. Internal fertilization occurs when sperm is released inside a female before she lays her eggs. This fertilization technique is seen in few frog species and may have evolved due to fast-paced aquatic environments. 

In frogs that use internal fertilization, males extend their cloaca into the females to release their sperm.

This allows the male to be the sole sire to the offspring and keep a steady hold on the female.

This mode of fertilization is commonly seen in tailed frogs of North America, Bufonids of Africa, and some species of Puerto Rico. 

Some females that utilize internal fertilization may deposit her fertilized eggs to be developed.

Some species give birth to young froglets after development inside the female’s body.

A male will not have to clasp the female in amplexus for long since the eggs will be deposited fertilized, but he may anyway. 

Migrations, Leks, Choruses, and Resource Guarding

Frogs participate in different behaviors to attract and keep a mate. These behaviors help ensure they will mate and pass their genetics to offspring.

Mating can be extremely taxing on frogs depending on the behaviors they exhibit.

Many frogs exhibit migrations to breeding grounds, resource guarding, scramble competition, and gathering into leks.  

Frogs will migrate to breeding grounds to participate in explosive mating behaviors.

This occurs when males are competing against other males for females. Males may scramble to locate females before they are outcompeted. 

Leks are described as display grounds where males will attempt to attract females to them.

Choruses are similar as males may use their vocal sacs to attract females. Using these methods, males will attempt to create a territory that females will be attracted to. 

Males may also resource guard to attract or keep a mate. They can resource guard a territory, thus guarding the females in that territory, or simply guard the mate.

Some males may follow their chosen female around so other males cannot attempt to mate with her. 

This article was written by Melissa M. who holds a Bachelors of Science in Fisheries and Wildlife Sciences, and a Master Herpetologist certificate. The article was edited and published by Daniella, Master Herpetologist in the author profile below.

Sources

Dedukh, D., Litvinchuk, J., Svinin, A., Litvinchuk, S., Rosanov, J., & Krasikova, A. (2019). Variation in hybridogenetic hybrid emergence between populations of water frogs from the Pelophylax esculentus complex. PLOS ONE. Retrieved from https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0224759 

Pough, F. H. (2018). Herpetology (4th ed.). Sinauer Associates, Inc., Publishers. 

Daniella Master Herpetologist

Daniella is a Master Herpetologist and the founder of toadsnfrogs.com, a website dedicated to educating the general population on frogs by meeting them where they are in their online Google Search. Daniella is passionate about frogs and put her digital marketing skills and teaching experience to good use by creating these helpful resources to encourage better education, understanding, and care for frogs.