The southern grass skink (''Pseudemoia entrecasteauxii)'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Scincidae. The species is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, where it is found in the south-east of the continent, as well as in

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

and the islands of

Bass Strait Bass Strait () is a strait separating the island state of Tasmania from the Australian mainland (more specifically the coast of Victoria, with the exception of the land border across Boundary Islet). The strait provides the most direct waterwa ...

. Although it occurs in a variety of habitats, it is most commonly found in open grassy

woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ''plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...

s. Cogger HG. (1979). ''Reptiles and Amphibians of Australia''. Sydney: Reed. The Southern grass skink has a lifespan of about 5 or 6 years. It grows up to in length (not including the tail). Male skinks change colouration during the breeding season.

Etymology

The specific name, ''entrecasteauxii'', is in honor of French naval officer and explorer

Antoine Bruni d'Entrecasteaux Antoine Raymond Joseph de Bruni, chevalier d'Entrecasteaux () (8 November 1737 – 21 July 1793) was a French naval officer, explorer and colonial governor. He is perhaps best known for his exploration of the Australian coast in 1792, while ...

Reproductive biology

The southern grass skink has become a model species for reproductive biology in reptiles because it gives birth to live young and exhibits non-invasive

epitheliochorial Placentation refers to the formation, type and structure, or arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remov ...

placentation Placentation refers to the formation, type and structure, or arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remov ...

. Unlike the majority of live bearing reptiles, ''Pseudemoia'' develop complex placentae, which provide a substantial amount of nutrients to the embryo through pregnancy. Pregnancy in squamates is supported by the evolution of a novel state of gene regulation. The amount of nutrients provided is dependent on the amount of food females consume during pregnancy, and, unlike other live-bearing reptiles, scarcity of food during pregnancy can cause developmental failure. When food is limiting, females will also cannibalize their offspring. Together, these results suggest that placental nutrient transport may only be a successful mode of reproduction if food is abundant throughout pregnancy, which may limit its opportunities to evolve in some reptiles. Lipid transport in this species most likely occurs through the yolk sac placenta and is facilitated in part by the production of the protein

lipoprotein lipase Lipoprotein lipase (LPL) (EC 3.1.1.34, systematic name triacylglycerol acylhydrolase (lipoprotein-dependent)) is a member of the lipase gene family, which includes pancreatic lipase, hepatic lipase, and endothelial lipase. It is a water-soluble ...

. The first observation of an

extra-uterine pregnancy Ectopic pregnancy is a complication of pregnancy in which the embryo attaches outside the uterus. Signs and symptoms classically include abdominal pain and vaginal bleeding, but fewer than 50 percent of affected women have both of these symptoms. ...

in a

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

was found in this species. The extra-uterine

embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...

did not invade maternal tissue, suggesting fundamental differences between the nature and

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

of placentation in southern grass skinks and

eutherian Eutheria (; from Greek , 'good, right' and , 'beast'; ) is the clade consisting of all therian mammals that are more closely related to placentals than to marsupials. Eutherians are distinguished from noneutherians by various phenotypic tra ...

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

References

{{Taxonbar, from=Q195999 Pseudemoia Skinks of Australia Reptiles described in 1839 Taxa named by André Marie Constant Duméril Taxa named by Gabriel Bibron