Join The Community Request new password. Main menu About this Site Table of Contents. SF Table 1. Marsupial mammals Marsupial Mammal Niche Photo of Mammal Kangaroo Large herbivore that forages extensively across open grasslands Wombat Medium-sized diurnal herbivore that feeds on grasses, constructs and dwells in extensive tunnel systems Thylacine Large, nocturnal fast moving predator that feeds on other mammals Tasmanian Devil Stocky nocturnal omnivore that primarily scavenges carrion and feeds on insects and plants Bandicoot Small foraging omnivore that eats insects and plants, small rodents, and lizards Quoll Small nocturnal carnivore that is an aggressive predator on small mammals, insects, and reptiles Numbat Diurnal insectivore that uses a specialized tongue to feed on ants and termites found in decaying wood Dunnart Small, nocturnal burrowing insectivore that builds nests of grass and plant material in dry areas SF Table 1.
Placental mammals Placental Mammal Niche Photo of Mammal Antelope Large herbivore that forages extensively across open grasslands Groundhog Medium-sized diurnal herbivore that feeds on grasses, constructs and dwells in extensive tunnel systems Wolf Large, nocturnal fast moving predator that feeds on other mammals Raccoon Stocky nocturnal omnivore that primarily scavenges carrion, and feeds on insects and plants Hedgehog Small foraging omnivore that eats insects, plants, small rodents, and lizards Weasel Small nocturnal carnivore that is an aggressive predator on small mammals, insects, and reptiles Anteater Diurnal insectivore that uses a specialized tongue to feed on ants and termites found in decaying wood Mouse Small, nocturnal burrowing insectivore that builds nests of grass and plant material in dry areas.
Question Set:. How are marsupial mammals different from placental mammals? Think of a common placental mammal not listed in SF Table 1. What marsupial species might have filled this same niche? With the exception of Australia, marsupials largely declined or went extinct in many regions, while placental mammals dominate to this day. Provide your own explanation for this phenomenon. Placental mammals all bear live young, which are nourished before birth in the mother's uterus through a specialized embryonic organ attached to the uterus wall, the placenta.
The placenta is derived from the same membranes that surround the embryos in the amniote eggs of reptiles, birds, and monotreme. The term "placental mammals" is somewhat of a misnomer because marsupials also have placentae. The difference is that the placenta of marsupials is very short-lived and does not make as much of a contribution to fetal nourishment as it does in eutherians , as "placental mammals" are known scientifically.
Looking ahead, it is worth noting that marsupials vary tremendously in reproductive traits Tyndale-Briscoe, , and that characterizing more species in the way that Guernsey et al. However, more work is needed to develop appropriate statistical methods for quantifying the conservation of transcriptome profiles between species. And looking beyond mammals, forms of placentation are found in everything from lizards, to seahorses, to insects, and preliminary studies indicate that many of the genes or traits involved are shared Ostrovsky et al.
It will be fascinating to learn how deeply we can trace the origins of the pregnancy toolkit. This article is distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use and redistribution provided that the original author and source are credited. Article citation count generated by polling the highest count across the following sources: Crossref , PubMed Central , Scopus.
Lactation is necessary for both infant and fetal development in eutherians and marsupials, although marsupials have a far more complex milk repertoire that facilitates morphogenesis of developmentally immature young.
In this study, we demonstrate that the anatomically simple tammar placenta expresses a dynamic molecular program that is reminiscent of eutherian placentation, including both fetal and maternal signals.
Further, we provide evidence that genes facilitating fetal development and nutrient transport display convergent co-option by placental and mammary gland cell types to optimize offspring success. Many developmental functions in marsupials and placental mammals are accomplished by different tissues, but similar genes. Cited 2 Views 5, Annotations Open annotations. The current annotation count on this page is being calculated.
Cite this article as: eLife ;6:e doi: Figure 1. Download asset Open asset. Langer P The phases of maternal investment in eutherian mammals Zoology — Evolution 69 — Marsupial reproduction: the choice between placentation and lactation, Oxford Reviews of Reproductive Biology, Vol.
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