Competitive interactions among rodents (Akodon azarae, Calomys laucha, Calomys musculinus and Oligoryzomys flavescens) in a two-habitat system. II. Effect of species removal.

Non-volant small mammals are key elements in natural environments due its importance as food resource. This study aimed to investigate the species composition and habitat occupancy by non-volant small mammals (Didelphimorphia, Rodentia) in a coastal grassland area in southern Rio Grande do Sul coastal plain. Between April 2009 and March 2010 pitffal traps were used to capture small mammals in coastal grasslands associated to sand dunes and arbustive Restinga. We sampled 180 individuals including two marsupials (Cryptonanus guahybae and Didelphis albiventris) and seven rodent species (Calomys laucha, Cavia aperea, Ctenomys flamarioni, Deltamys kempi, Oligoryzomys flavescens, Oxymycterus nasutus and Scapteromys tumidus). Cryptonanus guahybae, D. albiventris and C. flamarioni were captured only in dunes while C. aperea and O. nasutus were recorded only in arbustive Restinga habitats. Calomys laucha, D. kempi, O. flavescens and O. nasutus were captured in both habitats. Oligoryzomys flavescens and C. laucha were the most representative species in both habitats, comprising respectively 40.7 and 38.9% of captures in dunes and 56.3 and 34.9% of captures in Restinga habitats. The species richness recorded in the sampled coastal grasslands area was lower than those previously recorded in subtropical forest coastal systems.

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Density-dependent habitat selection between maize cropfields and their borders in two rodent species (Akodon azarae and Calomys laucha) of Pampean agroecosystems

Evolutionary Ecology ◽

10.1023/a:1010823128530 ◽

2000 ◽

Vol 14 (7) ◽

Cited By ~ 23

Author(s):

Karina Hodara ◽

María Busch ◽

Marcelo J. Kittlein ◽

Fernando O. Kravetz

Keyword(s):

Habitat Selection ◽

Rodent Species ◽

Density Dependent ◽

Akodon Azarae ◽

Density Dependent Habitat Selection ◽

Calomys Laucha

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Successful capacitation and homologous fertilization in vitro in Calomys musculinus and Calomys laucha (Rodentia - sigmodontinae)

Reproduction ◽

10.1530/reprod/120.1.41 ◽

2000 ◽

pp. 41-47 ◽

Cited By ~ 6

Author(s):

A Lasserre ◽

E Cebral ◽

AD Vitullo

Keyword(s):

In Vitro Fertilization ◽

Sperm Motility ◽

Acrosome Reaction ◽

Polar Body ◽

Laboratory Animals ◽

Fertilization In Vitro ◽

Vitro Fertilization ◽

Calomys Musculinus ◽

Calomys Laucha

Small South American rodents of the genus Calomys have been used extensively for virology and ecological research. Previous studies have demonstrated that Calomys musculinus and Calomys laucha have a relatively short oestrous cycle and that superovulation and parthenogenetic activation can be induced. The purpose of this study was to determine the requirements for in vitro manipulation of the male gamete and in vitro fertilization. Two culture media and different concentrations of spermatozoa were tested for their ability to support sperm motility, hyperactivation and the acrosome reaction. The ability of capacitated Calomys spermatozoa to penetrate zona-free hamster eggs was also evaluated. In vitro fertilization was assessed by examining attachment and binding to the zona pellucida, second polar body extrusion, pronucleus formation and the fertilizing sperm tail. The results of the study showed that: (i) Tyrode's albumin lactate pyruvate (TALP) medium was more effective than T6 medium for maintaining sperm motility in vitro; (ii) hyperactivation was achieved with TALP but not with T6; (iii) the acrosome reaction was easily distinguished by light microscopy and depends on time and sperm concentration; (iv) capacitated spermatozoa are able to penetrate zona-free hamster eggs; and (v) superovulated oocytes can be fertilized in vitro. This is the first report of capacitation and in vitro fertilization for Calomys sp. These results provide opportunities to use C. musculinus and C. laucha as new laboratory animals for research into reproductive biology.

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Seasonal Changes in Microhabitat Use and Niche Overlap between Akodon azarae and Calomys laucha (Rodentia, Muridae) in Agroecosystems of Central Argentina

Studies on Neotropical Fauna and Environment ◽

10.1076/snfe.34.3.129.8913 ◽

1999 ◽

Vol 34 (3) ◽

pp. 129-136 ◽

Cited By ~ 10

Author(s):

David N. Bilenca ◽

Fernando O. Kravetz

Keyword(s):

Seasonal Changes ◽

Niche Overlap ◽

Microhabitat Use ◽

Central Argentina ◽

Akodon Azarae ◽

Calomys Laucha

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Interspecific Social Relationships in Three Murid Rodent Species of Central Argentina, After Fasting and Unlimited Food

Behaviour ◽

10.1163/156853995x00018 ◽

1995 ◽

Vol 132 (11-12) ◽

pp. 811-820 ◽

Cited By ~ 4

Author(s):

David N. Bilenca ◽

Fernando O. Kravetz ◽

Gerardo R. Cueto

Keyword(s):

The Other ◽

Food Sources ◽

Feeding Time ◽

Murid Rodent ◽

Food Treatment ◽

Aggressive Interactions ◽

The Social ◽

Akodon Azarae ◽

Access To Food ◽

Oligoryzomys Flavescens

AbstractWe studied the social interactions between Akodon azarae and Calomys laucha, and between A. azarae and Oligoryzomys flavescens, by means of experimental confrontations under laboratory conditions. Trials were carried out after two treatments: in the first one ('food' treatment), the animals were offered food ad libitum permanently, whereas in the other ('fast' treatment), the animals were previously submitted to fasting for 30 hours. The largest species- A. azarae - dominated the other two species, being dominant in 69.6% of the aggressive interactions in which a clear dominant/subordinate relationship was detected (N = 79). During the 'fast' treatment, A. azarae fed longer than C. laucha and O. flavescens, and it was the only species which significantly increased its feeding time with respect to 'food' treatment. There were higher frequencies of aggressive interactions in A. azarae - C. laucha trials than in A. azarae - O. flavescens trials. Comparisons of the behavioural variables between C. laucha and O. flavescens during their respective confrontations with A. azarae showed that C. laucha had significantly higher median values of freezing and walking behaviours, whereas O. flavescens showed a higher frequency of alertness. Species differences found in the laboratory support the interpretation that A. azarae is usually dominant over C. laucha and O. flavescens, and that A. azarae has the priority of access to food sources in situations of food shortage (winter) by means of its social dominance over the other two species. We suggest that the differences in the behavioural reactions of the subordinate species when meeting the dominant one may help to explain the different scales of spatial segregation that C. laucha and O. flavescens maintain with A. azarae in the field.

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