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[Ornithology • 2017] Myzomela irianawidodoae • A Colourful New Species of Myzomela Honeyeater from Rote Island in eastern Indonesia ---ScRaBBlE

Myzomela irianawidodoae Prawiradilaga, Baveja, Suparno, Ashari, Ng, Gwee, Verbelen & Rheindt, 2017  photo:   Philippe Verbelen  e-journ...

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Showing posts with label Artiodactyla. Show all posts
Showing posts with label Artiodactyla. Show all posts

Wednesday, March 20, 2019

[PaleoMammalogy • 2017] The early Miocene Balaenid Morenocetus parvus from Patagonia (Argentina) and the Evolution of Right Whales ---ScRaBBlE


 Morenocetus parvus Cabrera, 1926
 Art by Jorge Gonzalez.

in Buono​, Fernández, Cozzuol, et al. 2017 

Abstract

Balaenidae (right and bowhead whales) are a key group in understanding baleen whale evolution, because they are the oldest surviving lineage of crown Mysticeti, with a fossil record that dates back ∼20 million years. However, this record is mostly Pliocene and younger, with most of the Miocene history of the clade remaining practically unknown. The earliest recognized balaenid is the early Miocene Morenocetus parvus Cabrera, 1926 from Argentina. M. parvus was originally briefly described from two incomplete crania, a mandible and some cervical vertebrae collected from the lower Miocene Gaiman Formation of Patagonia. Since then it has not been revised, thus remaining a frequently cited yet enigmatic fossil cetacean with great potential for shedding light on the early history of crown Mysticeti. Here we provide a detailed morphological description of this taxon and revisit its phylogenetic position. The phylogenetic analysis recovered the middle Miocene Peripolocetus as the earliest diverging balaenid, and Morenocetus as the sister taxon of all other balaenids. The analysis of cranial and periotic morphology of Morenocetus suggest that some of the specialized morphological traits of modern balaenids were acquired by the early Miocene and have remained essentially unchanged up to the present. Throughout balaenid evolution, morphological changes in skull arching and ventral displacement of the orbits appear to be coupled and functionally linked to mitigating a reduction of the field of vision. The body length of Morenocetus and other extinct balaenids was estimated and the evolution of body size in Balaenidae was reconstructed. Optimization of body length on our phylogeny of Balaenidae suggests that the primitive condition was a relatively small body length represented by Morenocetus, and that gigantism has been acquired independently at least twice (in Balaena mysticetus and Eubalaena spp.), with the earliest occurrence of this trait in the late Miocene–early Pliocene as represented by Eubalaena shinshuensis.


Figure 13: Reconstructions of balaenid crania in left lateral view, showing relative position of the orbit and eyeball (in blue) with arching of the rostrum. (A) Morenocetus parvus. (B) Balaenella brachyrhynus. (C) Eubalaena australis. The rostrum in (B) is depicted as preserved in the original specimen.

Figure 15: Artistic restoration of Morenocetus parvus in life. 
Art by Jorge Gonzalez. 

Systematic palaeontology

Cetacea Brisson, 1762
Neoceti Fordyce & Muizon, 2001

Mysticeti Gray, 1864 sensu Cope, 1869

Chaeomysticeti Mitchell, 1989
Balaenidae Gray, 1825

Morenocetus Cabrera, 1926

Type species by monotypy: Morenocetus parvus Cabrera, 1926.

....


Mónica R. Buono​, Marta S. Fernández, Mario A. Cozzuol, José I. Cuitiño and Erich M.G. Fitzgerald. 2017. The early Miocene Balaenid Morenocetus parvus from Patagonia (Argentina) and the Evolution of Right Whales.  PeerJ. 5:e4148.  DOI:  10.7717/peerj.4148

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روابط التحميل والمشاهدة، الروابط المباشرة للتحميل
او
شاهد هذا الفيديو القصير لطريقة التحميل البسيطة


كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا
شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا
رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا
تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

[Mammalogy • 2018] Multi-locus Phylogeny of the Tribe Tragelaphini (Mammalia, Bovidae) and Species Delimitation in Bushbuck: Evidence for Chromosomal Speciation Mediated by Interspecific Hybridization ---ScRaBBlE



in Hassanin, Houck, Tshikung,et al., 2018. 

Highlights
• Two species of bushbuck: Tragelaphus scriptus in NW Africa and T. sylvaticus in SE Africa.
• The two species have 2n = 57M/58F and 2n = 33M/34F chromosomes, respectively.
T. scriptus is related to T. angasii with mtDNA, and to T. sylvaticus with nuDNA.
 • Mitochondrial introgressive hybridization in the common ancestor of T. scriptus.
• Evidence for chromosomal speciation after an event of interspecific hybridization.


Abstract
The bushbuck is the most widespread bovid species in Africa. Previous mitochondrial studies have revealed a polyphyletic pattern suggesting the possible existence of two distinct species.

To assess this issue, we have sequenced 16 nuclear genes and one mitochondrial fragment (cytochrome b gene + control region) for most species of the tribe Tragelaphini, including seven bushbuck individuals belonging to the two divergent mtDNA haplogroups, Scriptus and Sylvaticus. Our phylogenetic analyses show that the Scriptus lineage is a sister-group of Sylvaticus in the nuclear tree, whereas it is related to Tragelaphus angasii in the mitochondrial tree. This mito-nuclear discordance indicates that the mitochondrial genome of Scriptus was acquired by introgression after one or several past events of hybridization between bushbuck and an extinct species closely related to T. angasii. The division into two bushbuck species is supported by the analyses of nuclear markers and by the karyotype here described for T. scriptus (2n= 57M/58F), which is strikingly distinct from the one previously found for T. sylvaticus (2n= 33M/34F). Molecular dating estimates suggest that the two species separated during the Early Pleistocene after an event of interspecific hybridization, which may have mediated massive chromosomal rearrangements in the common ancestor of T. scriptus.

Keywords: Spiral-horned antelopes, species complex, introgressive hybridization, chromosomes, cytogenetics


Figure 3. Bayesian divergence times (in million years ago, Mya) estimated using the nuclear concatenation of 16 genes (A) or the mitochondrial fragment (B). Divergence times were estimated with BEAST 2.4.7 (see main text for details). Taxa other than Tragelaphini were removed from the figures. Bold values at the nodes are mean ages. Grey bars and values between brackets represent the 95% Highest Posterior Density (HPD) interval.

 Alexandre Hassanin, Marlys L. Houck, Didier Tshikung, Blaise Kadjo, Heidi Davis and Anne Ropiquet. 2018. Multi-locus Phylogeny of the Tribe Tragelaphini (Mammalia, Bovidae) and Species Delimitation in Bushbuck: Evidence for Chromosomal Speciation Mediated by Interspecific Hybridization. Molecular Phylogenetics and Evolution. In Press.  DOI: 10.1016/j.ympev.2018.08.006 

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روابط التحميل والمشاهدة، الروابط المباشرة للتحميل
او
شاهد هذا الفيديو القصير لطريقة التحميل البسيطة


كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا
شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا
رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا
تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

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