Chromosome painting in the manatee supports Afrotheria and Paenungulata

Kellogg, Margaret E.; Burkett, Sandra; Dennis, Thomas R.; Stone, Gary; Gray, Brian A.; McGuire, Patricia; Zori, Roberto T.; Stanyon, Roscoe

doi:10.1186/1471-2148-7-6

Cited by 53 publications

(24 citation statements)

References 40 publications

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“…Placentation in the manatee resembles that in the African elephant (Amoroso and Perry 1964;Perry 1974;Allen et al 2003;Wooding et al 2005;Allen 2006). This is in agreement with our hypothesis, which was based on morphological, molecular and other evidence that Sirenia and Proboscidea are closely related (Gheerbrant et al 2005;Kellogg et al 2007). According to a recent cladistic analysis (Mess and Carter 2006), the earliest common ancestor of eutherian mammals had an endotheliochorial placenta, so this shared characteristic is plesiomorphic.…”

Section: Discussionsupporting

confidence: 82%

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Placentation in the Amazonian manatee (Trichechus inunguis)

Carter

Moody

Ambrósio

et al. 2008

Reprod. Fertil. Dev.

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Abstract. Evidence from several sources supports a close phylogenetic relationship between elephants and sirenians. To explore whether this was reflected in similar placentation, we examined eight delivered placentae from the Amazonian manatee using light microscopy and immunohistochemistry. In addition, the fetal placental circulation was described by scanning electron microscopy of vessel casts. The manatee placenta was zonary and endotheliochorial, like that of the elephant. The interhaemal barrier comprised maternal endothelium, cytotrophoblasts and fetal endothelium. We found columnar trophoblast beneath the chorionic plate and lining lacunae in this region, but there was no trace in the term placenta of haemophagous activity. The gross anatomy of the cord and fetal membranes was consistent with previous descriptions and included a four-chambered allantoic sac, as also found in the elephant and other afrotherians. Connective tissue septae descended from the chorionic plate and carried blood vessels to the labyrinth, where they gave rise to a dense capillary network. This appeared to drain into shorter vessels near the chorionic plate. The maternal vasculature could not be examined in the same detail, but maternal capillaries ran rather straight and roughly parallel to the fetal ones. Overall, there is a close resemblance in placentation between the manatee and the elephant.

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Section: Discussionsupporting

confidence: 82%

“…It has long been recognised that sirenians are closely related to elephants (Simpson 1945). Molecular and morphological evidence also groups them with the hyraxes in a clade named Paenungulata (Gheerbrant et al 2005;Kellogg et al 2007). The placentation of the African elephant has been studied in some detail.…”

Section: Introductionmentioning

confidence: 99%

Placentation in the Amazonian manatee (Trichechus inunguis)

Carter

Moody

Ambrósio

et al. 2008

Reprod. Fertil. Dev.

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“…Regarding lifestyle and body size, in contrast to the larger manatee/ dugong and the elephant, the hyrax may afford to raise more than one young. All three Orders, sirenia, hyracoideae and proboscidea, form together the Clade of Paenungulata [45]. The Paenungulata are assigned to the Superorder of Afrotheria, which also include mammals such as tenreks, aardvark and elephant shrews.…”

Section: Discussionmentioning

confidence: 99%

Gestating for 22 months: luteal development and pregnancy maintenance in elephants

Niemuller¹,

Rich²,

Gray³

et al. 2012

Proc. R. Soc. B.

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The corpus luteum, a temporally established endocrine gland, formed on the ovary from remaining cells of the ovulated follicle, plays a key role in maintaining the early mammalian pregnancy by secreting progesterone. Despite being a monovular species, 2-12 corpora lutea (CLs) were found on the elephant ovaries during their long pregnancy lasting on average 640 days. However, the function and the formation of the additional CLs and their meaning remain unexplained. Here, we show from the example of the elephant, the close relationship between the maternally determined luteal phase length, the formation of multiple luteal structures and their progestagen secretion, the timespan of early embryonic development until implantation and maternal recognition. Through three-dimensional and Colour Flow ultrasonography of the ovaries and the uterus, we conclude that pregnant elephants maintain active CL throughout gestation that appear as main source of progestagens. Two LH peaks during the follicular phase ensure the development of a set of 5.4 + 2.7 CLs. Accessory CLs (acCLs) form prior to ovulation after the first luteinizing hormone (LH) peak, while the ovulatory CL (ovCL) forms after the second LH peak. After five to six weeks (the normal luteal phase lifespan), all existing CLs begin to regress. However, they resume growing as soon as an embryo becomes ultrasonographically apparent on day 49 + 2. After this time, all pregnancy CLs grow significantly larger than in a non-conceptive luteal phase and are maintained until after parturition. The long luteal phase is congruent with a slow early embryonic development and luteal rescue only starts 'last minute', with presumed implantation of the embryo. Our findings demonstrate a highly successful reproductive solution, different from currently described mammalian models.

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“…The orders Hyracoidea and Sirenia are thought to have diverged nearly 60 million years ago [Pardini et al 2007; Springer et al 2003], although the phylogeny of Afrotheria remains intensely debated based on analyses that focus on morphological or molecular traits, or both (e.g., [Asher et al 2003; Cooper et al 2014; de Jong 1998; Gheerbrant 2009; Kellogg et al 2007; Kemp 2005; Kleinschmidt et al 1986; Lavergne et al 1996; Liu et al 2001; Murata et al 2003; Nishihara et al 2009; Ozawa et al 1997; Ruiz-Herrera and Robinson 2007; Shoshani and McKenna 1998; Springer et al 1997; Springer et al 2004]). Hyraxes appear to share many physiological characteristics with extant sirenia, including a low-quality food source and herbivorous lifestyle, poor thermoregulation, a relatively long gestation period, and few offspring [Olds and Shoshani 1982; Rubsamen et al 1982; Sale 1970b].…”

Section: Introductionmentioning

confidence: 99%

Elaboration and Innervation of the Vibrissal System in the Rock Hyrax <b><i>(Procavia capensis)</i></b>

Sarko¹,

Rice²,

Reep³

2015

Brain Behav Evol

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Mammalian tactile hairs are commonly found on specific, restricted regions of the body, but Florida manatees represent a unique exception, exhibiting follicle-sinus complexes (FSCs, also known as vibrissae or tactile hairs) on their entire body. The orders Sirenia (including manatees and dugongs) and Hyracoidea (hyraxes) are thought to have diverged approximately 60 million years ago, yet hyraxes are among the closest relatives to sirenians. We investigated the possibility that hyraxes, like manatees, are tactile specialists with vibrissae that cover the entire postfacial body. Previous studies suggested that rock hyraxes possess postfacial vibrissae in addition to pelage hair, but this observation was not verified through histological examination. Using a detailed immunohistochemical analysis, we characterized the gross morphology, innervation and mechanoreceptors present in FSCs sampled from facial and postfacial vibrissae body regions to determine that the long postfacial hairs on the hyrax body are in fact true vibrissae. The types and relative densities of mechanoreceptors associated with each FSC also appeared to be relatively consistent between facial and postfacial FSCs. The presence of vibrissae covering the hyrax body presumably facilitates navigation in the dark caves and rocky crevices of the hyrax's environment where visual cues are limited, and may alert the animal to predatory or conspecific threats approaching the body. Furthermore, the presence of vibrissae on the postfacial body in both manatees and hyraxes indicates that this distribution may represent the ancestral condition for the supraorder Paenungulata.

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Chromosome painting in the manatee supports Afrotheria and Paenungulata

Cited by 53 publications

References 40 publications

Placentation in the Amazonian manatee (Trichechus inunguis)

Placentation in the Amazonian manatee (Trichechus inunguis)

Gestating for 22 months: luteal development and pregnancy maintenance in elephants

Elaboration and Innervation of the Vibrissal System in the Rock Hyrax <b><i>(Procavia capensis)</i></b>

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