Diversity
The common name of species within genus
Ambystoma
is the mole salamander. There are approximately 33 species within this salamander
genus. Individuals vary in color and pattern, as some can be brightly colored while
others are duller in appearance. Coloration can also be heavily dependent upon age
and location. Western tiger salamanders (
Ambystoma californiense
) can be distinguished by their distinct pattern of black spots/bars. Northwestern
salamanders (
Ambystoma gracile
) can be distinguished based on their distinct paranoid glands and glandular ridge
on their tails. Long-toed salamanders (
Ambystoma macrodactylum
) have multiple subspecies that can be distinguished by their long toes and either
an apparent dorsal stripe or a series of blotches (Stebbins & McGinnis, 2018).
Geographic Range
Mole salamanders have a wide geographical range, though they are all found in the
Nearctic region. They range from Alaska to the Gulf Coast, as well as parts of the
Mexican Plateau. Four species of
Ambystoma
are found in the west. California tiger salamanders (
A. californiese
) can only be found in California, along with some hybrid populations. Western tiger
salamanders (
Ambystoma mavortium
) have a broader range in western North America, Canada, and Mexico. There are some
exceptions, including most of the Great Basin as well as the Pacific Coast, Mojave
deserts, and Coloradan deserts. Northwestern salamanders (
A. gracile
) range from California to Canada. Long-toed salamanders (
A. macrodactylum
) are found more inland than the other salamander species, such as in Santa Cruz,
California, and Canada (Stebbins & McGinnis, 2018). Streamside salamanders (
Ambystoma barbouri
) are found within a restricted range in Kentucky (Drayer et al., 2020).
Habitat
Ambystoma
species have a diverse habitat range.
A. mavortium
can be found in water ponds, reservoirs, lakes, and temporary rain pools in deserts,
mountains, and forests.
A. californiese
can be found within grasslands, oak savannas, low-elevation forests, and temporary
ponds for breeding.
A. gracile
can be found in open grasslands, woodlands, and in forests near water.
A. macrodactylum
can be found in sagebrush and cheatgrass as well as meadows and rocky shores (Stebbins
& McGinnis, 2018).
- Habitat Regions
- temperate
- terrestrial
- Terrestrial Biomes
- desert or dune
- forest
- scrub forest
- mountains
- Aquatic Biomes
- lakes and ponds
- rivers and streams
- temporary pools
- coastal
Systematic and Taxonomic History
Ambystoma
salamanders are closely related to other salamander species within order
Caudata
("Catalogue of Life", 2022; Stebbins & McGinnis, 2018). DNA evaluations indicate
that
Ambystoma
has been around for 2.4-5 million years (Spolsky et al., 1992; Bi et al., 2008).
Physical Description
Ambystoma
species typically have rounded, blunt snouts with a broad head and relatively small
eyes. They have prominent coastal grooves with a laterally flattened tail, which they
use for swimming. Compared to females, males have a longer tail and a bulbous vent.
As adults, many individuals have prominent markings such as spots, stripes, and bars.
However, some species are plain in color and pattern (Stebbins & McGinnis, 2018).
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- polymorphic
- Sexual Dimorphism
- male larger
Development
Some species within
Ambystoma
are pseudomorphic, meaning that they have larval characteristics that do not change.
The larvae can withstand cold temperatures, although some become neotenic over the
course of the winter (Stebbins & McGinnis, 2018).
- Development - Life Cycle
- neotenic/paedomorphic
- metamorphosis
Reproduction
Ambystoma
salamanders have internal fertilization and are polygynous (Stebbins & McGinnis,
2018). Most males exhibit sperm competition, as
Ambystoma
salamanders utilize a unique mating system in which males deposit a sperm package
known as a spermatophore, and females collect the spermatophore for use during internal
fertilization. The sperm will then make their way to her cloaca to fertilize her eggs
(Gopurenko et al., 2007; Stebbins & McGinnis, 2018).
- Mating System
- polygynous
Breeding is temperature-dependent and weather-dependent (Stebbins & McGinnis, 2018).
Ambystoma
species exhibit simple and complex courtship rituals, depending on the species. Those
that exhibit complex courtships tend to have a sex ratio favoring males (Gopurenko
et al., 2007).
- Key Reproductive Features
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- sperm-storing
Mole salamanders do not exhibit any parental care for their young; the females will
leave after laying their eggs (Stebbins & McGinnis, 2018; Gopurenko et al., 2007).
- Parental Investment
- no parental involvement
Lifespan/Longevity
Ambystoma
species have a relatively long lifespan, but the exact age range varies by species.
Their lifespan in captivity is thought to be about 25 years, however, a mature adult
has only been seen to live up to about 16 years (Tyning, 1990).
Behavior
Ambystoma
exhibit courtship behavior. They are generally solitary creatures with an exception
being the mating season (Gopurenko et al., 2007; Stebbins & McGinnis, 2018). During
non-mating seasons, the salamanders will stay inside logs and other damp, underground
places.
Ambystoma
is thought to be most active during the night (Stebbins & McGinnis, 2018).
Communication and Perception
While there are some heterospecific and homospecific calling cues in this genus, at
early stages of the salamanders' life cycles, they are not able to identify or distinguish
the calling cues (Gardner et al., 2020). Thus, juveniles' perception is mainly through
their olfactory senses (Park et al., 2003).
- Perception Channels
- chemical
Food Habits
Ambystoma
species feed on small invertebrates.
A. tigrinum
have been seen to prey on
Rana sylvatica
tadpoles (Wilbur, 1972). Some
A. mavortium
individuals exhibit cannibalistic behaviors, resulting in a different physical form
with wide, U-shaped mouths and enlarged teeth (Stebbins & McGinnis, 2018).
- Primary Diet
-
carnivore
- insectivore
- eats non-insect arthropods
- molluscivore
Predation
The main predators of
Ambystoma
are snakes and frogs (Stebbins & McGinnis, 2018).
Ambystoma
salamanders have evolved a unique anti-predator defense mechanism, secreting a liquid
from their skin that is considered unpalatable/toxic to predators. These salamanders
have other defense mechanisms as well, including aposematic coloration, defensive
postures, camouflage, and strategic tail-dropping (Thompson & Clark, 2022). However,
these salamanders are also seen as predators in their ecosystems since they feed on
small invertebrates (Wilbur, 1972).
- Anti-predator Adaptations
- aposematic
- cryptic
Ecosystem Roles
Ambystoma
salamanders are an indicator of their ecosystems' health. This is due to the high
permeability of their skin, which makes them susceptible to air and water pollution
(Davic & Welsh, 2004). These salamanders also have a key role in pest control, as
they eat insects and other small invertebrates (Wilbur, 1972).
Economic Importance for Humans: Positive
Ambystoma
do not directly impact the economy. They are, however, ecologically important as
an indicator of environmental health and a contributor to pest control (Davic & Welsh,
2004). They are also becoming more popular as pets, specifically the Mexican axolotl
(
Ambystoma mexicanum
) (Voss et al., 2015).
- Positive Impacts
- pet trade
- controls pest population
Economic Importance for Humans: Negative
There are no known adverse effects of Ambystoma on humans.
Conservation Status
Due to habitat disturbance, many
Ambystoma
species are becoming increasingly threatened. Currently, conservation efforts are
very slim due to continued pollution and increased habitat destruction. Thus, these
species are considered to be endangered and/or threatened (Davic & Welsh, 2004). California
tiger salamanders (
A. californiense
) are considered one of the endangered species in this genus (Stebbins & McGinnis,
2018).
Other Comments
The fossil history of this genus has revealed that tiger salamanders (
Ambystoma tigrinum
) are comprised of more than 22,000 elements throughout their lifetimes (Sertich et
al., 2014).
Additional Links
Contributors
Megan Roo (author), Colorado State University, Sydney Collins (editor), Colorado State University.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- terrestrial
-
Living on the ground.
- desert or dunes
-
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- mountains
-
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- polymorphic
-
"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.
- metamorphosis
-
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
- polygynous
-
having more than one female as a mate at one time
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- internal fertilization
-
fertilization takes place within the female's body
- sperm-storing
-
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- solitary
-
lives alone
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- chemical
-
uses smells or other chemicals to communicate
- aposematic
-
having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.
- cryptic
-
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
- pet trade
-
the business of buying and selling animals for people to keep in their homes as pets.
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
- molluscivore
-
eats mollusks, members of Phylum Mollusca
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