Plains spadefoot toad

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Plains spadefoot toad
Spea bombifrons.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Scaphiopodidae
Genus: Spea
Species:
S. bombifrons
Binomial name
Spea bombifrons
(Cope, 1863)
Synonyms

Scaphiopus bombifrons Cope, 1863
Spea bombifrons Cope, 1866

Contents

The plains spadefoot toad (Spea bombifrons) is a species of American spadefoot toad which ranges from southwestern Canada, throughout the Great Plains of the western United States, and into northern Mexico. Like other species of spadefoot toads, they get their name from a spade-like projection on their hind legs which allows them to dig into sandy soils. Their name, in part, comes from their keratinized metatarsals, which are wide instead of "sickle shaped". The species name translates as buzzing leaf shaped. [2] This refers to the species' distinguishing features; its buzzing mating call, and its leaf-shaped digging metatarsals. It was first described by Cope in 1863. [3]

Description

The plains spadefoot toad generally grows from 1.5 to 2.5 inches (3.8 to 6.4 cm) in length, has a round body, with relatively short legs. These toads are usually a tannish to dark brownish color with visible orange spots. They are one of the easiest anurans to recognize in their region because of their unique appearance. Sometimes, they have light striping on their backs.

Evolutionary and phylogenic relationships

The origins of Lissamphibia are not finalized. This has a lot to do with the fact that early stem amphibians were a lot more like amniotes in terms of biology. Much of amphibian biology appears to be derived evolution. The earliest known fossil of a burrowing frog is likely Prospea holoserisca . [4]

The most basal extant frog species are in the Archeabatrachia suborder. The most primitive frog is arguably Leiopelma .

Salienta fossils are the earliest examples of anurans that show a split from Order Caudata. Examples include Triadobatrachus and Czatkobatrachus .

Because amphibians might actually be highly derived, this could explain why their fossil record is poor. Multilocus sequence typing has proposed a Late Carboniferous/Early Permian origin around 270 mya. [5]

Geographical distribution and conservation status

This species is found throughout the Midwest from Alberta to Mexico wherever there is suitable soil for a fossorial lifestyle. The species is listed by IUCN 2015 as "least concern" and appears to be expanding its range, at least northwards into Alberta, Canada.

Ecology, behaviour and physiology

Spea bombifrons are famous for thriving in xeric environments, but a related species, Scaphiopus holbrookii has similar adaptation but does not live in similar extreme environments. The adults of this species is primarily fossorial for most of the year, but terrestrial during warm, wet periods. It only enters the water for breeding when nocturnal temperatures are at their yearly maximums and within 2–3 days of rain. [6] The tadpoles hatch from eggs after 2 days and metamorphose within 2 weeks. Froglets hide in cracks and shade and live off stored tissue in their tails until they can start feeding as adults.

Toads can only live where the ground is suitable for burrowing, and reproduce within 1 km of where they aestivate. [6] Like all amphibians, they are immobilized by low temperatures. This species prefers to burrow near large objects such as logs or rocks. They like to live near a water source, but this can be a subterranean patch of wet sand.

They have many predators, especially the hognose snake ( Heterodon nasicus ). Garter snakes predate most tadpoles, but often are not found in the desert, preferring riparian habitats. Many birds are opportunistic predators including burrowing owls and most wading birds. The tadpoles are also predated on by cannibal morphs, dragonfly larvae, giant scavenger beetles, and mosquito fish. Occasionally they will be eaten by Swainson's hawk and burrowing rodents. [7]

There have been a few parasites reported in at least 1 study: Polystoma nearcticum , Aplectana incerta, Aplectana itzocanensis, and Physaloptera spp. [8]

Behavior

Plains spadefoot toads are nocturnal and secretive. They spend most of the dryer seasons buried in the soil in estivation, typically only emerging during spring and fall rains. Breeding takes place in temporary pools of water left by rainfall, which requires the tadpoles to metamorphose quickly, before the water dries up. Eggs, laid in clutches numbering from 10 to 250, often hatch within 48 hours of being laid, and the larvae can change into tadpoles in as little as two weeks. The tadpoles exhibit phenotypic plasticity, with some changing from an omnivorous morphology into a cannibalistic carnivorous morph with oversized jaw muscles and pronged beaks. In some cases, female spadefoot toads will choose to mate with Spea multiplicata rather than with males of their own species, if the resulting hybrid tadpole would have higher chances of survival. [9] Character displacement has also been examined in ponds where Spea bombifrons and Spea multiplicata occur together. Reproductive and ecological competition between the two species likely causes selection for smaller and less reproductively successful individuals of Spea multiplicata. [10]

The adults travel by short hops and are generally poor swimmers. They swim in short bursts and only during periods of reproduction. this species is presumed to be non territorial and solitary except during breeding season. Satellite males have been shown to attempt to intercept females arriving at a breeding pond and are successful in about 20% of cases. Dominant, or first arriving males signal vocally from the deepest part of the ephemeral pool. Amplexus is a necessary stimulus to release eggs. Once the eggs are fertilized, there is little apparent parental care. The adults are strictly live insectivores. The tadpoles are detritivores, either scavengers or herbivores depending on morph

Tadpole "nests" can bee seen in most xeric amphibians, and are well described in the fossil record, such as at the St. George Dinosaur Discovery site. The shallow depressions are a form of "vortex feeding" used to stir up debris for feeding. It is also theorized that the depressions formed could allow a lengthened hydroperiod to increase growth size.

Sensory modalities

Both tadpoles and adults have many senses. Studies support a theory that olfactory sense is important to tadpoles of this species. [11] Adult breeding frogs detect breeding ponds by using auditory cues from other frog calls to gauge distance, size of pool, likelihood of predators and numbers as well as breeding condition of other frogs. Sources say frogs use low frequency sound of rain as a cue to emerge from aestivation. [12] While olfactory cues are considered a secondary emergence stimulus, there is evidence in other anurans that the smell of emergent plant growth can also guide frogs to breeding sites, specifically pond weed species. Persistent emergent behaviour has been observed personally when a piece of moss was placed in an enclosure of two captive Spea bombifrons.[ citation needed ]

Anuran tadpoles almost always have evidence of neuromasts arranged in lateral lines, although these only exist in adults of fully aquatic species, of which there are surprisingly few. There is poor research on how tadpoles use this sensory input during development.

Frog hearing is unique in that the lungs act as amplifiers for the hearing. [13] Their columella-operculum complex has been theorized as a method they can use to detect earthquakes.

Frogs have a unique form of green rods in their retinas which is theorized to help them see at very low light levels. [14]

Physiology

Frogs in general, but fossorial frogs specifically are able to absorb water through a "seat patch" instead of drinking. The skin is selectively permeable via aquaporins, allowing them to absorb water from damp ground, standing water, and mossy substrates.

According to David Pfenning's lab at the University of North Carolina, Desert spadefoots appear able to not only adapt their bodies to a carnivorous diet (Shorter gut, protein-digesting genes are activated) but also are more likely to have progeny that are adapted to meat.[ citation needed ] This is a major study that shows that Lamarckian characteristics are not as disproven as once thought.[ citation needed ]

Both Spea species found in North America have been used for many years in the North Carolina lab of Karin Pfennig as model organisms to study hybridization and its effects on competition and evolution. [15] The results appear to be mixed, but there is evidence of resource competition being linked to species divergence.

Related Research Articles

<span class="mw-page-title-main">Frog</span> Order of amphibians

A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura. The oldest fossil "proto-frog" Triadobatrachus is known from the Early Triassic of Madagascar, but molecular clock dating suggests their split from other amphibians may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest. Frogs account for around 88% of extant amphibian species. They are also one of the five most diverse vertebrate orders. Warty frog species tend to be called toads, but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history.

<span class="mw-page-title-main">Tadpole</span> Larval stage in the life cycle of an amphibian

A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found in adult amphibians such as a lateral line, gills and swimming tails. As they undergo metamorphosis, they start to develop functional lungs for breathing air, and the diet of tadpoles changes drastically.

<span class="mw-page-title-main">Ornate chorus frog</span> Species of amphibian

The ornate chorus frog is a species of chorus frog endemic to the Southeastern United States. Their distribution ranges from North Carolina, east to the very eastern part of Louisiana, and south to northern parts of Florida.

<span class="mw-page-title-main">Common frog</span> Species of amphibian

The common frog or grass frog, also known as the European common frog, European common brown frog, European grass frog, European Holarctic true frog, European pond frog or European brown frog, is a semi-aquatic amphibian of the family Ranidae, found throughout much of Europe as far north as Scandinavia and as far east as the Urals, except for most of the Iberian Peninsula, southern Italy, and the southern Balkans. The farthest west it can be found is Ireland. It is also found in Asia, and eastward to Japan. The nominative, and most common, subspecies Rana temporaria temporaria is a largely terrestrial frog native to Europe. It is distributed throughout northern Europe and can be found in Ireland, the Isle of Lewis and as far east as Japan.

<span class="mw-page-title-main">Wood frog</span> Species of amphibian

Lithobates sylvaticus or Rana sylvatica, commonly known as the wood frog, is a frog species that has a broad distribution over North America, extending from the boreal forest of the north to the southern Appalachians, with several notable disjunct populations including lowland eastern North Carolina. The wood frog has garnered attention from biologists because of its freeze tolerance, relatively great degree of terrestrialism, interesting habitat associations, and relatively long-range movements.

<span class="mw-page-title-main">European spadefoot toad</span> Family of amphibians

The European spadefoot toads are a family of frogs, the Pelobatidae, with only one extant genus Pelobates, containing six species. They are native to Europe, the Mediterranean, northwestern Africa, and western Asia.

<span class="mw-page-title-main">American spadefoot toad</span> Family of amphibians

The Scaphiopodidae are a family of American spadefoot toads, which are native to North America. The family is small, comprising only seven different species.

<i>Spea hammondii</i> Species of amphibian

Spea hammondii, also known as the western spadefoot, western spadefoot toad, Hammond's spadefoot, or Hammond's spadefoot toad, is a species of amphibian in the family Scaphiopodidae. It is found in western California (USA) and northwestern Baja California (Mexico). The specific name hammondii is in honor of physician and naturalist William Alexander Hammond.

<i>Scaphiopus</i> Genus of amphibians

Scaphiopus is a genus of North American amphibian commonly referred to as the North American spadefoots, southern spadefoots, or eastern spadefoot toads. They differ greatly from true toads by having eyes with vertical pupils, no parotoid gland, and relatively smooth skin. Their most distinctive feature is a spade-like projection on their hind feet, from which their common name is derived. This projection enables spadefoot toads to dig in loose soils with ease. Its scientific name means ‘spade-foot’ as well, from the Ancient Greek skaphís and pous.

<i>Spea</i> Genus of amphibians

Spea is a genus of North American amphibian commonly referred to as the western spadefoot toads. They differ greatly from true toads by having eyes with vertical pupils, no parotoid glands, and relatively smooth skin. Their most distinctive feature is a spade-like projection on their hind feet, from which their common name is derived. This projection enables spadefoot toads to dig in loose soils with ease. Its name is from the Ancient Greek speos

<span class="mw-page-title-main">Couch's spadefoot toad</span> Species of amphibian

Couch's spadefoot toad or Couch's spadefoot is a species of North American spadefoot toad. The specific epithet couchii is in honor of American naturalist Darius Nash Couch, who collected the first specimen while on a personal expedition to northern Mexico to collect plant, mineral, and animal specimens for the Smithsonian Institution.

<i>Gastrophryne carolinensis</i> Species of amphibian

Gastrophryne carolinensis, the eastern narrow-mouthed toad, is a species of microhylid frog. It is a relatively small, toad-like amphibian found in damp, shady habitats. The species is highly fossorial, and feeds primarily on ants. These North American microhylids are distinguished from true toads, and other anurans by their moist, smooth skin, their lack of eardrums or tympana, their distinguishable squat body shape, and the unique fold of skin superior to their eyes. It is found in the United States, from southern Maryland to the Florida Keys, west to Missouri and Texas. While not a true toad, it is so called because it is terrestrial.

<span class="mw-page-title-main">New Mexico spadefoot toad</span> Species of amphibian

The New Mexico spadefoot toad is a species of American spadefoot toad found in the southwestern United States and Mexico. Like other species of spadefoot toad, they get their name from a distinctive spade-like projections on their hind legs which enable them to dig in sandy soils. Spea multiplicata can be identified by its wedge-shaped spade. Some sources also refer to the species as the Mexican spadefoot toad, desert spadefoot toad or southern spadefoot toad.

<span class="mw-page-title-main">Crucifix toad</span> Species of amphibian

The crucifix toad, holy cross frog or Catholic frog is a species of frog in the family Limnodynastidae. It is a fossorial frog. It is one of the few Australian frogs to display aposematism. It is native to western New South Wales and south-western Queensland.

<i>Scaphiopus holbrookii</i> Species of amphibian

Scaphiopus holbrookii, commonly known as the eastern spadefoot, is a species of American spadefoot toad endemic to North America. It is not considered a true toad.

<span class="mw-page-title-main">Yosemite toad</span> Species of amphibian

The Yosemite toad is a species of true toad in the family Bufonidae. Endemic to the Sierra Nevada of California, the species ranges from the Alpine County to Fresno County. Yosemite toads are only found in the montane to subalpine elevational zone of 1,950–3,445 m (6,398–11,302 ft) asl. The Yosemite toad is similar to the nearby western toad, but in many ways adapted to a high elevation lifestyle. It was initially described during the Grinnell Survey of California, by an undergraduate student of Joseph Grinnell named Charles Camp.

<span class="mw-page-title-main">Great Basin spadefoot</span> Species of amphibian

The Great Basin spadefoot is an amphibian in the family Scaphiopodidae. It is 3.8 to 6.3 centimetres long and is usually colored gray, olive or brown. Great Basin spadefoot toads have adapted to life in dry habitats. They use the hard, keratinized spade on each foot to dig a burrow, where they spend long periods during cold and dry weather. They are opportunistic hunters and will eat anything they can subdue. While their tadpoles have numerous predators, adults are able to produce skin secretions that deter enemies.

Flexible or opportunistic breeders mate whenever the conditions of their environment become favorable. Their ability and motivation to mate are primarily independent of day-length (photoperiod) and instead rely on cues from short-term changes in local conditions like rainfall, food abundance and temperature. Another factor is the presence of suitable breeding sites, which may only form with heavy rain or other environmental changes.

References

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  2. "Frogs and Toads - River Science". www.kansasriverscience.org. Retrieved 2019-11-12.
  3. "Cope, 1863, Proc. Acad. Nat. Sci. Philadelphia, 15 | Amphibian Species of the World". research.amnh.org. Retrieved 2019-11-27.
  4. Chen, C; Bever, S; Yi, Y; Norell., A (2016). "Chen, J., G.S. Bever, H. Yi, and M. A. Norell, 2016. A burrowing frog from the late Paleocene of Mongolia uncovers a deep history of spadefoot toads (Pelobatoidea) in East Asia. Scientific Reports. 6, 19209. [X23961] (matrix)". doi:10.7934/x23961.{{cite journal}}: Cite journal requires |journal= (help)
  5. San Mauro, Diego; Vences, Miguel; Alcobendas, Marina; Zardoya, Rafael; Meyer, Axel (2005-05-01). "Initial Diversification of Living Amphibians Predated the Breakup of Pangaea". The American Naturalist. 165 (5): 590–599. doi:10.1086/429523. ISSN   0003-0147. PMID   15795855. S2CID   17021360.
  6. 1 2 Bragg, Arthur (1965). Gnomes of the Night: The spadefoot toads. University of Pennsylvania Press. p. 50. ISBN   9781512800678.
  7. Lannoo, Michael (2005). Amphibian Declines: The Conservation Status of United States Species. University of California Press. ISBN   9780520235922.
  8. Goldberg, Stephen (2002). "Helminths of the plains spadefoot, Spea bombifrons, the western spadefoot, Spea harmondi, and the Great Basin spadefoot, Spea intermontana (Pelobatidae)". Western North American Naturalist. 62 (4): 13.
  9. Pfennig, Karin S. (2007-11-09). "Facultative Mate Choice Drives Adaptive Hybridization". Science. 318 (5852): 965–967. Bibcode:2007Sci...318..965P. doi:10.1126/science.1146035. PMID   17991861. S2CID   31080177.
  10. Pfennig, Karin S; David W Pfennig (October 2005). "Character displacement as the "best of a bad situation": fitness trade-offs resulting from selection to minimize resource and mate competition". Evolution. 59 (10): 2200–2208. doi: 10.1111/j.0014-3820.2005.tb00928.x . ISSN   0014-3820. PMID   16405163.
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  12. Dimmitt, M (1980). "Environmental correlates of emergence in spadefoot toads (Scaphiopus)". Journal of Herpetology. 14 (1): 21–29. doi:10.2307/1563871. JSTOR   1563871.
  13. Schoffelen, R (2008). "Mechanics of the exceptional anuran ear". Journal of Comparative Physiology A. 194 (5): 417–428. doi:10.1007/s00359-008-0327-1. PMC   2323032 . PMID   18386018.
  14. Yovanovich, CAM (2017). "The dual rod system of amphibians supports colour discrimination at the absolute visual threshold". Philosophical Transactions of the Royal Society B. 372 (1717): 20160066. doi:10.1098/rstb.2016.0066. PMC   5312016 . PMID   28193811.
  15. Garcia, N (April 2015). "Leptin Manipulation Reduces Appetite and Causes a Switch in Mating Preference in the Plains Spadefoot Toad (Spea bombifrons)". PLOS ONE. Ecollection 2015 (4): e0125981. Bibcode:2015PLoSO..1025981G. doi: 10.1371/journal.pone.0125981 . PMC   4412710 . PMID   25919309. S2CID   17163233.