Rodriguez-Refojos C.,Aranzadi Society of science |
Zuberogoitia I.,Icarus |
Rosalino L.M.,University of Lisbon |
Santos M.J.,Sebero Otxoa 45 |
And 3 more authors.
Folia Zoologica | Year: 2011
Animals' body size varies intra-specifically and geographically among populations, and many species (including small carnivores) show sexual dimorphism and larger individuals (lower superficial area/volume ratio) inhabiting cooler climates complying with Bergman's rule. In the present study we analyse data of common genets wild-caught in three different regions of the Iberian Peninsula, searching for variations in size and weight between males and females, testing for sexual dimorphism, as well as for micro-scale geographical variations among populations in biometrics and sexual dimorphism. We use field measurements such as length (body and tail) and weight, to characterise the three populations in the Iberian Peninsula. Our results show that Iberian genets present significant differences between sexes, although sexual dimorphism is lower than in other small carnivores, and that they comply with Rensch's rule, males size showing greater variation. Iberian genets also follow the Bergman's rule, being bigger and heavier in colder and northern regions. Although we have detected morphometric differences among studied populations, sexual dimorphism indexes varied little. We discuss our results in the light of the different hypotheses given to explain the sexual dimorphism in carnivores, trying to identify the mechanisms that might play a role in the dimorphism of genets.
Morales J.,University of Salamanca |
Ruiz-Olmo J.,Direccio General del Medi Natural |
Lizana M.,University of Salamanca |
Gutierrez J.,University of Salamanca
Ethology Ecology and Evolution | Year: 2015
An experiment was performed with two subadult otters (Lutra lutra) born in captivity that had never seen or eaten amphibians, in which they were fed a new prey with toxic substances in its skin, the Iberian common toad (Bufo spinosus). It was observed that the otters recognised a poisonous amphibian that they had never come into contact with before as a potential prey in the absence of fish, which had previously been their only diet. As from the first test, and as described for wild otters in the literature, they consumed the toads following a learning process that consisted of ventral slicing and skinning in order to avoid contact with the dermal secretions, especially on the head and back, that toads use as a defensive mechanism. We observed the skill of the otters when handling the prey with regards to both killing them and eating them; the otters also immersed their prey in the water of their pond to remove the toxic substances emanating from the toads’ skins. The amount of remains left after the attack was gradually reduced over a period of 16 test experiments. No differences between the skins rejected in the experimental conditions and those found in nature were detected, the otter mainly eating the back legs and taking special care to reject the head, the back and viscera (especially the ovaries in the case of pregnant females). When they had brown trout together with toads in the same biomass, they neither attacked nor consumed the latter. © 2015 Dipartimento di Biologia, Università di Firenze, Italia
Romero R.,University of Santiago de Compostela |
Guitian J.,University of Santiago de Compostela |
Ruiz-Olmo J.,Direccio General del Medi Natural
Journal of Zoology | Year: 2012
In November 2002 the Prestige tanker spilled 59000tonnes of oil off Galicia (north-west Spain) and contaminated a vast coastal area extending from northern Portugal to Brittany (France). Two study areas, a coastal lagoon (1 sample point) and a stretch of rocky coast (includes 5 sample points), were selected to examine changes on the diet of otters Lutra lutra L. before and after the oil spill. Diet was assessed from 1103 spraints, 553 collected in 2000, before the spill and 550 in 2003, after the spill. In the coastal lagoon, after spill, spraints contained more shrimp (Palaemon sp.), more prey of marine origin, and fewer gobies (Pomatoschistus sp.) and eels Anguilla anguilla. A decline of the eel population in the coastal lagoon may have caused otters to make more frequent visits to the sea. On the rocky coast, spraints contained more blennids in 1 of the 5 sampling points, however, the seasonal patterns of the principal prey species (Blennidae, Gadidae and Labridae) were similar across the 2years of study. The differences may be attributed to common interannual variations in the diet of marine otters, but the design of this study cannot assess the degree of natural variation in the diet of coastal otters before the oil spill. © 2011 The Authors. Journal compilation © 2011 The Zoological Society of London.
Espadaler X.,Autonomous University of Barcelona |
Olmo-Vidal J.M.,Direccio General Del Medi Natural
Sociobiology | Year: 2011
Two species of myrmecophilous crickets, Myrmecophilus acervorum and Myrmecophilus ochraceus, are here established as present in the Iberian Peninsula. The generic host range for M. acervorum is limited to one genus, Lasius. The host range of M. ochraceus is wider, Camponotus, Messor, Monomorium, and Tetramorium. The identity of specimens from the Balearic Islands remains controversial.