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1

Allozyme genetic distances and evolutionary relationships in marsupials of North and South America

100%
Barrantes G. E., Daleffe L.
Acta Theriologica
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1999
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tom 44
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nr 3
AUozyme genetic distances and variability were studied by horizontal starch gel electrophoresis in 6 species of marsupials from North and South America representing 4 different genera. Twenty-one presumptive loci were assessed in a total of 151 specimens. Only 1 of 21 loci was found to be monomorphic in the whole sample. Phenetic and cladistic interspecific analysis coincided in rendering two sharply dif­ferentiated subgroups: one comprising species of the genus Didelphis Linnaeus, 1758 CD. marsupialis Linnaeus, 1758, D. virginiana Kerr, 1792 and D. albiventris Lund, 1840), and the other comprising Monodelphis dimidiata fWagner, 1847}, Lestodelphys halli (Thomas, 1921) and Lutreolina crassicaudata (Desmarest, 1804). No relationships between the bradytelic condition, the karyotype stability of this group, and genetic variability were found. On the other hand, the existence of species with brief life span such as Lestodelphys halli and Monodelphis dimidiata (Marmosini tribe) and species with long life span (Didelphini tribe) allowed us to test the hypothesis which correlates generation-time with genetic variability. We conclude that a general explanation for genetic variability must involve more than just generation-time,
2

Stride lengths and frequencies of arboreal walking in seven species of didelphid marsupials

100%
Delciellos A. C., Vieira M. V.
Acta Theriologica
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2007
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tom 52
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nr 1
Didelphid marsupials differ in their use of the forest strata, with corresponding differences in morphology and arboreal walking performances. Similar performances may be reached by different combinations of stride length and frequency, but it has been suggested that arboreal walkers increase velocity by longer strides. Our objective was to determine how stride length and frequency contribute to the velocity in the arboreal walking of seven species of didelphid marsupials of the Atlantic Forest of Brazil. Animals were stimulated to cross five 3-m long horizontal supports of different diameters. The cycle of maximum velocity was chosen to measure relative stride length, frequency, and relative velocity. Except forCaluromys philander, the more arboreal species were faster than the terrestrial species, but maximum velocity of arboreal species was reached by two strategies, increasing stride frequency (Gracilinanus microtarsus, Micoureus demerarae, andDidelphis aurita), or reducing frequency and increasing stride length (Marmosops incanus andC. philander). Increasing velocity in arboreal walking by more frequent strides may reduce oscillations of the body, whereas longer strides may reduce branch swaying. Among the terrestrial species,Philander frenatus performed similarly to more arboreal species, suggesting a potential ability to use the canopy, undetected in field observations.
3

Marsupial larvae of Sinanodonta woodiana (Lea, 1834) (Bivalvia: Unionoida: Unionidae)

84%
Labecka A. M., Domagala J.
Acta Biologica Cracoviensia. Series Botanica. Supplement
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2008
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tom 50
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nr 1
4

Effects of resource availability on the use of space by the mouse opossum Marmosops paulensis [Didelphidae] in a montane Atlantic forest area in Southeastern Brazil

84%
Leiner N. O., Silva W. R.
Acta Theriologica
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2007
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tom 52
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nr 2
Food supply is an important determinant of animal movements. In the present study we tested the occurrence of an inverse relationship between daily movements ofMarmosops paulensis (Tate, 1931) and their food supply. This species is a member of the family Didelphidae, occurring in areas of high elevation in the Brazilian Atlantic Forest.M. paulensis moved mostly over the ground, although the understory was also used. Mean daily range ofM. paulensis estimated through spool-and-line device was about 0.40 ha; no differences were noted between body sizes and sexes. As expected, there was an inverse relationship between daily movements and food supply. This relationship resulted from the clumped distribution of fruits, particularlyPiper rather than the sparser distribution of arthropods.
5

Movement distances and density estimation of small mammals using the spool-and-line technique

84%
Mendel S. M., Vieira M. V.
Acta Theriologica
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2003
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tom 48
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nr 3
Edge effect is an inherent problem when using trapping grids to estimate density of small mammals, resulting in a sampling area larger than the area of the grid. Distances between captures of individuals are used to estimate A(W), the effective sampling area of a trapping grid, but grid size sets a limit for the largest detectable distance. The spool-and-line technique is proposed here as a new method to estimate A(W). Movement distances based on the spool-and-line technique were compared to similar movement distances based on capture-recapture of three species of marsupials of the Atlantic Forest of Brazil. Distances based on the two methods were uncorrelated, and only ln-transformed distances based on the spool-and-line were normally distributed. The maximum distance moved (MaxD) estimated by the spool-and-line was chosen as the more accurate and practical distance to estimate edge effect. Estimates of the effective sampling area and densities for the common opossum Didelphis aurita (Wied-Neuwied, 1826), were compared using MaxD based on spool-and-line (MaxDspool), capture-recapture (MaxDcap), and also the distance between traps (DT). MaxDspool reflected more accurately density variation between seasons. Movement distances of small mammals based on the spool-and-line technique permit more accurate estimates of density and its dynamics.
6

Cranial ontogeny of Lutreolina crassicaudata (Didelphidae): a comparison with Didelphis albiventris

84%
Flores D. A., Giannini N. P., Abdala F.
Acta Theriologica
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2003
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tom 48
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nr 1
Metatherians experience the greatest developmental changes during extrauterine life. Following previous studies on Didelphis albiventris Lund, 1840, we examined the postweaning cranial allometry of size of the Neotropical marsupial Lutreolina cras- sicaudata (Desmerest, 1804). Our aim was to compare growth patterns of both species to identify traits particular to each species and traits common to both species. This may contribute toward identifying a common developmental plan for didelphids. We mea­sured 15 cranial variables in 32-43 specimens from just-weaned young to old adult. Total length of the skull was the estimator of overall size in least squares and reduced major axis regressions. The skull of Lutreolina crassicaudata grows at a rate slower than the overall change in size in its neurocranial components, palate, and postcanine rows, and it grows relatively faster in the rest of the splanchnocranium. This pattern closely resembles that of Didelphis albiventris, from which it differs mainly in the allometry of the muzzle. In both species, allometry explains most postweaning changes of the trophic apparatus on functional grounds, in relation to interspecific differences in diet. We hypothesize that most local allometric departures from a generalized didelphid plan would relate to main dietary trends.
7
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Marsupials from the Late Cretaceous of Uzbekistan

84%
Averianov A., Kielan-Jaworowska Z.
Acta Palaeontologica Polonica
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1999
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tom 44
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nr 1
A fragment of dentary with m4, showing characters of some Late Cretaceous North American marsupials, is assigned to Marsasia sp. Marsasia Nessov, 1997 from the Coniacian of Uzbekistan, represented by M. aenigma known from edentulous dentaries with inflected angular processes, was attributed by Nessov to ?Marsupialia. Marsasia sp., found in the same horizon as the type species, resembles it in size and structure of the masseteric fossa, but dffiers in having a less steep coronoid process. We assign Marsasia to Marsupialia on the basis of the following characters: inflected angular process, shape of the dentary similar to that in Asiatherium, postcanine dental formula, inferred from alveoli for p1-3, ml-4, and sfructure of m4 more similar to Cretaceous marsupials than eutherians. The phylogenetic position of Marsasia may be between the Albian Kokopellia and Campanian Asiatherium. Marsasia is tentatively referred to the orderAsiadelphia, which may represent an endemic Asian marsupial clade.
8
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A revision of 'pediomyid' marsupials from the Late Cretaceous of North America

84%
Davis B. M.
Acta Palaeontologica Polonica
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2007
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tom 52
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nr 2
“Pediomyids” are a diverse group of smallto medium−sized marsupials which comprise a significant portion of many Late Cretaceous North American mammalian faunas. Known almost exclusively from isolated teeth and jaw fragments, “pediomyids” exhibit far more diversity than any other contemporaneous group of North American mammals. This has led some to suggest that the family “Pediomyidae” is an artificial, polyphyletic assemblage composed of multiple lineages that independently acquired various traditionally−recognized “pediomyid” molar characters, such as a reduction of the anterior stylar shelf, reduction of the stylocone and a labial shift in the attachment of the cristid obliqua. The present study seeks to elucidate the interrelationships of “pediomyid” marsupials and test the monophyly of the group using cladistic methodology, including a broad sampling of Late Cretaceous North American taxa and a comprehensive set of qualitative molar characters. Results suggest that the family “Pediomyidae” and the genus “Pediomys” are both polyphyletic and are in need of systematic revision. Iqualadelphis lactea (Aquilan) appears to be unrelated to the “pediomyid” radiation, and rests as a stem taxon near the base of the cladogram. The large Aquilan Aquiladelphis nests in a trichotomy with a strictly−defined “Pediomyidae” and the enigmatic Lancian taxon Glasbius, suggesting the possibility of a distant relationship (above the familial level). Three clades are recognized within the “Pediomyidae”: a restricted Pediomys, Leptalestes gen. nov. (containing the three smallest species), and Protolambda (containing the remaining three larger species). Results suggest that “Pediomys” exiguus is a stem taxon lacking a close relationship to Pediomyidae sensu stricto, and is removed to permit recognition of the family as monophyletic. The results carry implications for the role “pediomyids” might have played in the initial North American marsupial radiation sometime prior to the Campanian, and the pattern of molar evolution throughout major Late Cretaceous lineages.
9

Mammalian evolution underground. The ecological-genetic-phenetic interfaces

67%
Nevo E.
Acta Theriologica. Supplement
|
1995
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nr 03
The global adaptive convergence of subterranean mammals currently involves 3 orders: rodents, insectivores and marsupials. These include 11 families, 50 genera, and several hundreds of species. This global evolutionary process followed the stepwise climatic cooling and drought followed by biotic extinction in the transition from the middle Eocene to the early Oligocene, a period of 10 million years (35-45 Ma = million years ago), of profound change in earth geology, climate and biota. The earth changed from the Mesozoic "hot house" to the Neogene (Miocene to Present) "cold house", ie from a warm, equable, mostly subtropical world that persisted from the Mesozoic to the beginning of the present glaciated world. The ecological theater of open country biotas, that opened up progressively in the Cenozoic following the Eocene-Oligocene transition, was associated with increasing aridity, colder climate, and terrestrialism. This climatic change set the stage for a rapid evolutionary play of recurrent adaptive radiations of unrelated mammals on all continents into the subterranean ecotope. The subterranean ecotope is relatively simple, stable, specialised, low or medium in productivity, predictable and discontinuous. Its major evolutionary determinants are specialization, competition and isolation. This ecotope involves the herbivorous (rodents) and insectivorous (insectivores and marsupials) niches. All subterranean mammals share molecular and organismal convergent adaptations to their common unique ecology. By contrast, they display divergent adaptations to their separated niches of herbivory and insectivory and to their different phylogenies. The remarkable adaptive evolution of subterranean mammals involves adaptive structural and functional progression and regression. It is one of the most dramatic examples of global convergent evolution due to underground ecological constraints, at both the molecular and organismal levels of evolutionary theory.
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