Perote ground squirrel

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Perote ground squirrel
Perote-Ziesel - Xerospermophilus perotensis 385157.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Genus: Xerospermophilus
Species:
X. perotensis
Binomial name
Xerospermophilus perotensis
(Merriam, 1893)
Synonyms

Spermophilus perotensisMerriam, 1893

The Perote ground squirrel (Xerospermosphilus perotensis) is a species of rodent in the family Sciuridae. [2] It is endemic to Mexico and is currently at risk of extinction. Perote ground squirrels live within the same area as rock squirrels ( Otospermophilus variegatus ) but they use different microhabitats. In one case it also shares its habitat with the Mexican ground squirrel (Ictidomys mexicanus). [3] Perote ground squirrels have traits similar to those of spotted ground squirrels ( X. spilosoma pallescens ) found in the northern Mexican Plateau; however they are larger, have shorter tails and yellow backs. Its skull is relatively narrow with a large braincase and they have heavy, thick teeth. [4] Perote ground squirrels have two annual cycles, an active phase (March–November) and a hibernation phase (December–February). Some overlap may occur in March and November however. [5]

Contents

X. perotensis was first described as a species in 1893. Much research is being done recently, and many scientists think it should be classified as a subspecies of X. spilosoma . "In either case, and regardless of the position one might adopt around species concepts, it is evident that X. perotensis constitutes an independent and isolated biological entity that has evolved under restricted geographical and ecological contexts as a consequence of recent Pleistocene events". [5]

Phylogeny

The Perote ground squirrel’s closest relative is believed to be the spotted ground squirrel (X. spilosoma) which split from each other 1.2-3.3 million years ago as a result of climate shifts during the Pleistocene. [6]

Distribution and habitat

distribution of the Perote ground squirrel in Mexico Xerospermophilus perotensis distribution map.png
distribution of the Perote ground squirrel in Mexico

The habitat range of the Perote ground squirrel is in the Oriental Basin (5250 km2) between Puebla and Veracruz. The basin is surrounded by high mountains [6] thought to have arisen from volcanic activity. This also accounts for the pockets of arid and semiarid land. [4] The semiarid land in Perote is the most humid in the area with an average rainfall of 369.77 mm between June and September. The average temperature is 11.9 °C with highs of 14.73 °C and lows of 8.80 °C. [3]

Perote ground squirrels only live in alkaline grasslands, arid scrubs and hilly, rocky areas where they will dig their burrows. However, due to agriculture, overgrazing, and the urbanizing of the area, the suitable habitat for the squirrel is down to 16 small localities. These areas are mostly narrow strips (20–50 m) separated by an average distance of 15.8 km. [6]

This species is threatened by extensive habitat fragmentation and deforestation within its restricted range due to timber extraction and clearing of forest for agriculture. While the squirrel once occupied a range of approximately 5250 square kilometers, it now only occupies an area totaling 2457 square kilometers. [3] The Oriental Basin is surrounded almost entirely by a belt of temperate mountain ranges, which prevent the squirrel from dispersing to new habitat. [4] The Oriental Basin is made up of lava flows, isolated mountains, and volcanoes and so provides only localized habitable areas.

Diet

X. perotenses is a generalist species in its diet. It is mostly found in croplands and open areas with low vegetation. [5] In most studies, researchers bait traps with oats in order to catch individuals.

Life history and reproduction

Perote ground squirrels form family groups within individual burrow systems. In some cases males will leave the burrow to locate females in dispersed areas. This causes aggression between adults and yearling males that ultimately leads to further male migration. [6] Adult males become active in March (before sub-adults and females). Copulation occurs between April and May and pregnant and/or lactating females were most common in June–August. The average number of embryos was found to be six, where the average number of live juveniles was four. [3]

Due to the habitat destruction and fragmentation of land, there are fewer opportunities for breeding between genetically diverse individuals. Perote ground squirrels have been seen mating within their own family, which may lead to inbreeding. However, results have shown that "no inbreeding coefficient value for any population was significantly different from zero, implying that inbreeding had little effect on genetic structure." [6]

Genetic diversity and conservation

Due to the increased fragmentation of the ground squirrels native habitat, they have suffered a sharp decrease in genetic diversity. By comparing mitochondrial DNA of current populations with historic museum specimens, scientists have observed a decrease in haplotype and nucleotide diversity. [6] Because of rapid generation times and large effective population sizes, Sciurids are expected to exhibit high numbers of haplotypes; however, the Perote Ground Squirrel is an exception to the rule. Scientists are concerned that this loss of genetic diversity may contribute to their eventual extinction. It is recommended that management action be taken to help increase genetic diversity; the most likely solution being a relocation of certain individuals within each of the 16 populations.

Threats

Species can respond to environmental change in one of three possible ways: (a) migrating; that is, tracking their ecological niche throughout the geographic space. The Perote ground squirrel has such particular environmental needs that they do not have a place to migrate. (b) adapting in terms of evolutionary change and/or physiological acclimation; and (c) becoming locally extinct." [5]

Some studies have found that because the Perote ground squirrel is a seasonal species, it is more affected by climate change, increasing the risk of extinction. Seasonal species are more vulnerable because they are forced to do all their annual activities in a shorter amount of time. They do not migrate and have to adjust their activities, such as hibernation, with the current climate. [5]

The squirrel also has predators such as the long-tailed weasel ( Mustela frenata ) and domestic dogs, which have impacts on population. [6]

Future

"Ground-dwelling small mammals are key species, considered as ecosystem engineers because of their positive effects on soil condition, by introducing organic matter, favoring water infiltration and modifying its physical structure, thus enriching vegetation composition and favoring phreatic aquifer maintenance. Their burrows often provide microhabitats for other vertebrate and invertebrate species. In addition, ground squirrels are important prey for several predator species, some of which highly depend on them during their breeding season." [5] If the ground squirrel were to go extinct, there would be a dramatic change in the ecosystem.

There are many gaps in the studies of the Perote ground squirrel. Even though it is endangered, we have much to learn. Maybe further studies may provide an answer on how we can conserve this keystone species of the Oriental Basin in Mexico. Unfortunately, many experts fear the squirrel will go extinct without human intervention.

Related Research Articles

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<span class="mw-page-title-main">Franklin's ground squirrel</span> Species of rodent

Franklin's ground squirrel is a species of squirrel native to North America, and the only member of the genus Poliocitellus. Due to the destruction of prairie, the populations of Franklin's ground squirrel have dwindled, approaching levels of concern. Its decline in the eastern portion of its range is mostly attributed to habitat fragmentation.

<span class="mw-page-title-main">Northern Idaho ground squirrel</span> Species of rodent

The northern Idaho ground squirrel is a species of the largest genus of ground squirrels. This species and the Southern Idaho ground squirrel were previously considered conspecific, together called the Idaho ground squirrel.

<span class="mw-page-title-main">Hoary marmot</span> Species of rodent

The hoary marmot is a species of marmot that inhabits the mountains of northwest North America. Hoary marmots live near the tree line on slopes with grasses and forbs to eat and rocky areas for cover.

<span class="mw-page-title-main">Habitat fragmentation</span> Discontinuities in an organisms environment causing population fragmentation.

Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes that slowly alter the layout of the physical environment, and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species. More specifically, habitat fragmentation is a process by which large and contiguous habitats get divided into smaller, isolated patches of habitats.

Genetic viability is the ability of the genes present to allow a cell, organism or population to survive and reproduce. The term is generally used to mean the chance or ability of a population to avoid the problems of inbreeding. Less commonly genetic viability can also be used in respect to a single cell or on an individual level.

<span class="mw-page-title-main">Mohave ground squirrel</span> Species of rodent

The Mohave ground squirrel is a species of ground squirrel found only in the Mojave Desert in California. The squirrel was first described in 1886 by Frank Stephens of San Diego. It is listed as a threatened species under the California Endangered Species Act, but not under the federal Endangered Species Act. The IUCN lists this species as near threatened.

Extinction vortices are a class of models through which conservation biologists, geneticists and ecologists can understand the dynamics of and categorize extinctions in the context of their causes. This model shows the events that ultimately lead small populations to become increasingly vulnerable as they spiral toward extinction. Developed by M. E. Gilpin and M. E. Soulé in 1986, there are currently four classes of extinction vortices. The first two deal with environmental factors that have an effect on the ecosystem or community level, such as disturbance, pollution, habitat loss etc. Whereas the second two deal with genetic factors such as inbreeding depression and outbreeding depression, genetic drift etc.

<span class="mw-page-title-main">Round-tailed ground squirrel</span> Species of rodent

The round-tailed ground squirrel, known as "Ardillón cola redonda" in Spanish, live in the desert of the Southwestern United States and Northwestern Mexico. They are called "ground squirrels" because they burrow in loose soil, often under mesquite trees and creosote bushes.

<span class="mw-page-title-main">Tropical ground squirrel</span> Species of rodent

The tropical ground squirrel is a species of rodent in the family Sciuridae. At one time the species was originally described as Spermophilus adocetus, but the genus Spermophilus was revised and subdivided in 2009 and it was placed in the genus Notocitellus. It is endemic to arid upland areas and deciduous woodland in Mexico. It is locally referred to as Cuinique.

<span class="mw-page-title-main">Mexican ground squirrel</span> Species of rodent

The Mexican ground squirrel is a species of rodent in the family Sciuridae. It is found in Mexico and the United States. One of its closest relatives is the thirteen-lined ground squirrel.

<span class="mw-page-title-main">Spotted ground squirrel</span> Species of squirrel

The spotted ground squirrel is a species of ground squirrel in the rodent family Sciuridae. It is found throughout Mexico and the central and western United States. Characterized by a white spotted back, the spotted ground squirrel is one of the smallest squirrels found in North America. They are mainly herbivorous, but also eat insects. A burrowing mammal, the spotted ground squirrel will make tunnels to store its food, as well as shelter and hibernation quarters.

<span class="mw-page-title-main">Speckled ground squirrel</span> Species of rodent

The speckled ground squirrel or spotted souslik is a species of rodent in the family Sciuridae from Eastern Europe. Spermophilus suslicus consists of three subspecies: S. s. boristhenicus, S. s. guttatus, and S. s. suslicus. It is threatened by habitat loss.

<span class="mw-page-title-main">Rock squirrel</span> Species of rodent

The rock squirrel is a species of rodent in the family Sciuridae. It is native to Mexico and the Southwestern United States, including southern Nevada, Utah, Colorado, Arizona, New Mexico, West Texas, and the panhandle of Oklahoma.

<span class="mw-page-title-main">Colorado chipmunk</span> Species of rodent

The Colorado chipmunk is a species of chipmunk in the squirrel family Sciuridae. It is endemic to Colorado, Utah, Arizona and New Mexico in the United States.

<span class="mw-page-title-main">Mearns's squirrel</span> Subspecies of rodent

Mearns's squirrel is a subspecies of the Douglas squirrel endemic to Mexico. It is endangered and occurs in low densities, and is threatened by habitat loss. It is possibly also threatened by competition from the eastern gray squirrel, which was introduced to the range of Mearns's squirrel in 1946, but may not be present anymore. It is closely related to other subspecies of the Douglas squirrel, but far less is known about its behavior, which was first studied in detail in 2004. It is named for the 19th-century American naturalist Edgar Mearns.

<span class="mw-page-title-main">Unstriped ground squirrel</span> Species of rodent

The unstriped ground squirrel is a species of rodent in the family Sciuridae. It is the only member of the genus Xerus. It is found in Djibouti, Eritrea, Ethiopia, Kenya, Somalia, Sudan, Tanzania, and Uganda. Its natural habitats are dry savanna and subtropical or tropical dry shrubland.

Genetic erosion is a process where the limited gene pool of an endangered species diminishes even more when reproductive individuals die off before reproducing with others in their endangered low population. The term is sometimes used in a narrow sense, such as when describing the loss of particular alleles or genes, as well as being used more broadly, as when referring to the loss of a phenotype or whole species.

<i>Xerospermophilus</i> Genus of rodents

Pygmy ground squirrels are small ground squirrels in the genus Xerospermophilus, family Sciuridae, containing four species from Mexico and the United States. The members of this genus were formerly placed in the large ground squirrel genus Spermophilus. Since DNA sequencing of the cytochrome b gene showed that Spermophilus was paraphyletic to the prairie dogs and marmots, this group is now separated, along with six other genera. Within the genus, the Mohave ground squirrel and the round-tailed ground squirrel were thought to be close relatives, sometimes a subgenus Xerospermophilus, while the spotted ground squirrel and the Perote ground squirrel were formerly placed in the subgenus Ictidomys.

<span class="mw-page-title-main">Population fragmentation</span> Form of population segregation

Population fragmentation is a form of population segregation. It is often caused by habitat fragmentation.

References

  1. Álvarez-Castañeda, S.T.; Lacher, T.; Vázquez, E. (2016). "Xerospermophilus perotensis". IUCN Red List of Threatened Species . 2016: e.T20489A22264586. doi: 10.2305/IUCN.UK.2016-3.RLTS.T20489A22264586.en . Retrieved 15 November 2021.
  2. Thorington, R.W. Jr; Hoffman, R.S. (2005). "Family Sciuridae". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 810. ISBN   978-0-8018-8221-0. OCLC   62265494.
  3. 1 2 3 4 Valdez, M.; Ceballos, G. (1997-02-21). "Conservation of Endemic Mammals of Mexico: The Perote Ground Squirrel (Spermophilus perotensis)". Journal of Mammalogy. 78 (1): 74–82. doi:10.2307/1382640. ISSN   1545-1542.
  4. 1 2 3 Fernández, Jesús A. (2012-12-17). "Phylogenetics and biogeography of the microendemic rodent Xerospermophilus perotensis (Perote ground squirrel) in the Oriental Basin of Mexico". Journal of Mammalogy. 93 (6): 1431–1439. doi:10.1644/11-MAMM-A-409.1. ISSN   0022-2372.
  5. 1 2 3 4 5 6 García-Domínguez, José Arturo; Rojas-Soto, Octavio Rafael; Galindo-González, Jorge R.; González-Romero, Alberto; del Rosario Pineda-López, María; Noa-Carrazana, Juan Carlos (2014-01-23). "Present and future potential distribution of the endemic Perote ground squirrel (Xerospermophilus perotensis) under different climate change scenarios". mammalia. 0 (0): 1–15. doi:10.1515/mammalia-2013-0077. ISSN   1864-1547.
  6. 1 2 3 4 5 6 7 Ochoa, Alexander; Gasca, Jaime; Ceballos, Gerardo J.; Eguiarte, Luis E. (2012-09-14). "Spatiotemporal population genetics of the endangered Perote ground squirrel ( Xerospermophilus perotensis ) in a fragmented landscape". Journal of Mammalogy. 93 (4): 1061–1074. doi:10.1644/11-MAMM-A-371.1. ISSN   0022-2372.