Genomic, karyological, and morphological changes of South American garlics ( Ipheion ) provide insights into mechanisms of speciation in the Pampean region

The Pampean Region contains sedimentary sequences with abundant mammal fossil records, which constitute the chronological outline of the Plio–Pleistocene of South America. These classic localities have been used for more than a century to correlate with other South American regions. Throughout this time, a series of misinterpretations have appeared. To understand the stratigraphic significance of these localities and the geochronological situation of each unit referring to the Pleistocene, a critical historical study of the antecedents was carried out, evaluating the state of each unit. The biostratigraphic studies of the Pampean Region’s mammalian faunas improved the understanding of biogeographic changes taking into account the environmental fluctuations of the Pleistocene.

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Direct evidence of megamammal-carnivore interaction decoded from bone marks in historical fossil collections from the Pampean region

PeerJ ◽

10.7717/peerj.3117 ◽

2017 ◽

Vol 5 ◽

pp. e3117 ◽

Cited By ~ 1

Author(s):

Karina Vanesa Chichkoyan ◽

Borja Figueirido ◽

Margarita Belinchón ◽

José Luis Lanata ◽

Anne-Marie Moigne ◽

...

Keyword(s):

Direct Evidence ◽

Popular Media ◽

South American ◽

Long Bones ◽

Ecological Interactions ◽

Predator Prey ◽

Ecological Relationships ◽

Pampean Region ◽

Fossil Bones ◽

Crucial Information

Pleistocene South American megafauna has traditionally attracted the interest of scientists and the popular media alike. However, ecological interactions between the species that inhabited these ecosystems, such as predator-prey relationships or interspecific competition, are poorly known. To this regard, carnivore marks imprinted on the fossil bones of megamammal remains are very useful for deciphering biological activity and, hence, potential interspecific relationships among taxa. In this article, we study historical fossil collections housed in different European and Argentinean museums that were excavated during the 19th and early 20th centuries in the Pampean region, Argentina, in order to detect carnivore marks on bones of megamammals and provide crucial information on the ecological relationships between South American taxa during the Pleistocene. Our results indicate that the long bones of megafauna from the Pampean region (e.g., the Mylodontidae and Toxodontidae families) exhibit carnivore marks. Furthermore, long bones of medium-sized species and indeterminate bones also present punctures, pits, scores and fractures. Members of the large-carnivore guild, such as ursids, canids and even felids, are recognised as the main agents that inflicted the marks. We hypothesize that the analysed carnivore marks represent the last stages of megaherbivore carcass exploitation, suggesting full consumption of these animals by the same or multiple taxa in a hunting and/or scavenging scenario. Moreover, our observations provide novel insights that help further our understanding of the palaeoecological relationships of these unique communities of megamammals.

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Cryopreservation‐induced morphological changes in the sperm of South American silver catfish ( Rhamdia quelen )

Journal of Applied Ichthyology ◽

10.1111/jai.13928 ◽

2019 ◽

Author(s):

Bruna B. da Costa ◽

Lis S. Marques ◽

Paula G. Lassen ◽

Rômulo B. Rodrigues ◽

Danilo P. Streit

Keyword(s):

Morphological Changes ◽

South American ◽

Silver Catfish ◽

Rhamdia Quelen

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The fossil record of Ceratophrys Wied-Neuwied (Anura: Ceratophryidae): a revision and update of fossil South American horned frogs

Zootaxa ◽

10.11646/zootaxa.4658.1.2 ◽

2019 ◽

Vol 4658 (1) ◽

pp. 37-68

Author(s):

LAURA NICOLI

Keyword(s):

Fossil Record ◽

South American ◽

Unique Combination ◽

Fossil Species ◽

Environmental Tolerance ◽

Pampean Region ◽

Fossil Material ◽

Extant Species ◽

Present Distribution ◽

Living Species

Ceratophrys is the most diverse and widely distributed genus of Ceratophryidae, the clade of South American horned frogs. Numerous anuran fossil remains, including several fossil species, have been assigned to this genus. However, this seemingly extensive fossil record is problematic because several of the fossils are not properly identified and most of the taxonomic assignations are not justified. The present study traces all the fossil material attributed to Ceratophrys, clarifying, when possible, institutional allocations. Each of the remains was examined and its taxonomic assignation revisited, based on the morphology and possible synapomorphies of the genus, including its living species. Numerous fossils were properly identified and assigned with certainty to Ceratophrys. Only one fossil species, Ceratophrys ameghinorum, is considered valid. This information, along with recently reported evidence of fossil Ceratophrys, is briefly summarized to serve as a practical reference for the entire known fossil record of the genus. The fossil record is not especially informative about the evolution or distribution pattern of Ceratophrys, because most of the remains are relatively young (post-Miocene), collected within the present distribution of the genus, and morphologically consistent with that of the extant species. However, some useful information has emerged. The presence of Ceratophrys is well documented since the Neogene in the Pampean Region of South America. The single valid fossil species, Ceratophrys ameghinorum, possesses a unique combination of characters that reflects a mixture of characters observed in different clades of the genus; thus, resolution of its phylogentic position will inform our understanding of the evolution of the genus. The paleoenvironmental significance of some Ceratophrys fossils is also discussed, addressing the wide, but incompletely known current distribution and environmental tolerance of the genus.

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Phenotypic plasticity associated to environmental hypoxia in the neotropical serrasalmid Piaractus mesopotamicus (Holmberg, 1887) (Characiformes: Serrasalmidae)

Neotropical Ichthyology ◽

10.1590/1982-0224-20150187 ◽

2016 ◽

Vol 14 (2) ◽

Cited By ~ 1

Author(s):

María Alejandra Fernández-Osuna ◽

Pablo Augusto Scarabotti

Keyword(s):

Morphological Changes ◽

Experimental Studies ◽

South American ◽

Threshold Values ◽

Functional Link ◽

Lower Lip ◽

Piaractus Mesopotamicus ◽

Valve Development ◽

Similar Threshold ◽

Distal Border

ABSTRACT Many South American characid fishes develop reversible dermal protuberances in the jaws to optimize aquatic surface respiration (ASR) during hypoxia. To date, basic aspects of this adaptation remain unknown, mainly due to the scarcity of experimental studies. In laboratory experiments, we determined time necessary for the complete formation and reversion of these structures in Piaractus mesopotamicus , and studied comparatively behavioral, morphological, and respiratory responses along gradients of dissolved oxygen (DO) concentration. Morphological changes during hypoxia consisted in dermal protuberances of lower lip, anterior border of maxillary and distal border of opercular valve, increasing the known number of structures modified. These structures developed completely in less than 6 hours and reversed in less than 3 hours. Most of observed traits showed a logistic response curve with threshold DO values between 0.90 and 2.70 mgL-1. Respiratory frequency and opercular valve development showed similar threshold values above the level of tolerance of DO, whereas ASR and dermal protuberances of the jaws showed threshold values below this level. This observation supports the functional link between these groups of behavioral and morphological traits. This study demonstrates that this species is able to modify reversibly portions of the respiratory system to optimize responses to hypoxia.

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Morphological and molecular species boundaries in the Hyalella species flock of Lake Titicaca (Crustacea: Amphipoda)

Contributions to Zoology ◽

10.1163/18759866-bja10004 ◽

2020 ◽

Vol 89 (4) ◽

pp. 353-372

Author(s):

José A. Jurado-Rivera ◽

Francesco Zapelloni ◽

Joan Pons ◽

Carlos Juan ◽

Damià Jaume

Keyword(s):

Molecular Species ◽

Incomplete Lineage Sorting ◽

Morphological Changes ◽

Water Bodies ◽

Species Flock ◽

South American ◽

Lineage Sorting ◽

Lake Titicaca ◽

Genetic Lineages ◽

Andean Altiplano

The Hyalella species diversity in the high-altitude water bodies of the Andean Altiplano is addressed using mitochondrial cox1 sequences and implementing different molecular species delimitation criteria. We have recorded the presence of five major genetic lineages in the Altiplano, of which one seems to be exclusive to Lake Titicaca and nearby areas, whereas the rest occur also in other regions of South America. Eleven out of 36 South American entities diagnosed by molecular delimitation criteria in our study are likely endemic to the Titicaca and neighbouring water bodies. We have detected a remarkable disagreement between morphology and genetic data in the Titicacan Hyalella, with occurrence of several cases of the same morpho-species corresponding to several Molecular Operational Taxonomic Units (MOTUs), some even distantly related, and other instances where a particular MOTU is shared by a morphologically heterogeneous array of species, including species with body smooth and others with body heavily armoured. Species diversification and incongruence between morphological and molecular boundaries within this species assemblage may be associated to the sharp changes in hydrological conditions experienced by the water bodies of the Altiplano in the past, which included dramatic fluctuations in water level and salinity of Lake Titicaca. Such environmental shifts could have triggered rapid morphological changes and ecological differentiation within the Hyalella assemblage, followed by phenotypic convergence among the diverse lineages. Factors such as phenotypic plasticity, incomplete lineage sorting or admixture between divergent lineages might lie also at the root of the morphological-genetic incongruence described herein.

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South American lake paleo-records across the Pampean Region

PAGES news ◽

10.22498/pages.17.3.115 ◽

2009 ◽

Vol 17 (3) ◽

pp. 115-117 ◽

Cited By ~ 11

Author(s):

Felipe García-Rodríguez ◽

E Piovano ◽

L del Puerto ◽

H Inda ◽

S Stutz ◽

...

Keyword(s):

South American ◽

Pampean Region

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The largest known bear, Arctotherium angustidens, from the early Pleistocene Pampean region of Argentina: with a discussion of size and diet trends in bears

Journal of Paleontology ◽

10.1666/10-037.1 ◽

2011 ◽

Vol 85 (1) ◽

pp. 69-75 ◽

Cited By ~ 24

Author(s):

Leopoldo H. Soibelzon ◽

Blaine W. Schubert

Keyword(s):

South America ◽

Early Pleistocene ◽

Middle Pleistocene ◽

Buenos Aires Province ◽

South American ◽

Pampean Region ◽

Great American Biotic Interchange ◽

Epiphyseal Fusion ◽

Evolutionary Trajectories ◽

Serious Injuries

The South American giant short-faced bear (Arctotherium angustidens Gervais and Ameghino, 1880) is one of five described Arctotherium species endemic to South America and it is known for being the earliest, largest, and most carnivorous member of the genus. Here we report an extraordinarily large A. angustidens individual exhumed from Ensenadan sediments (early to middle Pleistocene) at Buenos Aires Province, Argentina. Based on overall size, degree of epiphyseal fusion, and pathologies, this bear was an old-aged male that sustained serious injuries during life. Body mass of the bear is estimated and compared to other ursid species based on a series of allometric equations. To our knowledge, this specimen now represents the largest bear ever recorded. In light of this discovery, we discuss the evolution of body size in Arctotherium (from large-to-small) and compare this to bears that exhibited different evolutionary trajectories. We suggest that the larger size and more carnivorous nature of A. angustidens, compared to later members of the genus, may reflect the relative lack of other large carnivores and abundance of herbivores in South America just after the Great American Biotic Interchange.

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Generalized Tuberculosis in a South American Frog Leptodactylus pentadactylus

Pathologia veterinaria ◽

10.1177/030098586600300504 ◽

1966 ◽

Vol 3 (5) ◽

pp. 451-460 ◽

Cited By ~ 4

Author(s):

U. F. Rowlatt ◽

F. J. C. Roe

Keyword(s):

Morphological Changes ◽

Disease Process ◽

Causative Organism ◽

Systemic Effects ◽

South American ◽

Granulomatous Lesion ◽

Acid Fast Bacilli ◽

American Frog ◽

The Right

A frog is described which had chronic visceral tuberculosis for some time before an acute, granulomatous lesion, in which acid-fast bacilli were identified, appeared in the right eye. In the absence of culture of the causative organism, the diagnosis was inferred from the presence of characteristic morphological changes. The disease process is essentially similar to that in man but the systemic effects are much less marked.

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Morphological Changes in the Rat Granulosa Cell Surface During Differentiation Induced by Estradiol and Gonadotropins

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079851 ◽

1977 ◽

Vol 35 ◽

pp. 484-485

Author(s):

P. Bagavandoss ◽

JoAnne S. Richards ◽

A. Rees Midgley

Keyword(s):

Cell Surface ◽

Granulosa Cell ◽

Morphological Changes ◽

Follicular Development ◽

Female Rats ◽

Functional Changes ◽

Group 4 ◽

Group 3 ◽

Group 5 ◽

Group 2

During follicular development in the mammalian ovary, several functional changes occur in the granulosa cells in response to steroid hormones and gonadotropins (1,2). In particular, marked changes in the content of membrane-associated receptors for the gonadotropins have been observed (1).We report here scanning electron microscope observations of morphological changes that occur on the granulosa cell surface in response to the administration of estradiol, human follicle stimulating hormone (hFSH), and human chorionic gonadotropin (hCG).Immature female rats that were hypophysectcmized on day 24 of age were treated in the following manner. Group 1: control groups were injected once a day with 0.1 ml phosphate buffered saline (PBS) for 3 days; group 2: estradiol (1.5 mg/0.2 ml propylene glycol) once a day for 3 days; group 3: estradiol for 3 days followed by 2 days of hFSH (1 μg/0.1 ml) twice daily, group 4: same as in group 3; group 5: same as in group 3 with a final injection of hCG (5 IU/0.1 ml) on the fifth day.

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