Extinction of the autochthonous small mammals of Mallorca (Gymnesic Islands, Western Mediterranean) and its ecological consequences

Aim To investigate the chronology, causes and consequences of the extinction of the autochthonous Pleistocene small mammals of Mallorca. Location Mallorca (Gymnesic Islands, Balearics, Western Mediterranean). Methods We have obtained the first direct ¹⁴C ages from the bone collagen of selected samples of two extinct endemic small mammals from Mallorca: the Balearic dormouse, Eliomys morpheus (Rodentia: Myoxidae) and the Balearic shrew, Asoriculus hidalgoi (Soricomorpha: Soricidae). We also present evidence for the absence of both endemics from the earliest Mallorcan archaeological sites and for the introduction of the garden dormouse, Eliomys quercinus, and the wood mouse, Apodemus sylvaticus. Combined information from direct dating of bone collagen of E. quercinus and A. sylvaticus and from cultural associations provides an adequate framework to establish the chronology of the faunal change and to compare it with the chronological information available on climatic change and the first arrival of humans on the islands. Results The chronological record includes the latest evidence available for the survival of endemic species and the earliest introduction of small mammals into Mallorca. We present ‘uncertainty periods for extinction’ (UPEs) of both endemic mammals based on the chronology of their last occurrence and on the inferred timing of their extinction (restricted UPEs). Main conclusions Possible causes for the extinction of autochthonous small mammals on Mallorca are discussed. Once we have discarded climatic causes, predation by invasive species, competition with newcomers and habitat deterioration, the introduction of diseases emerges as the most reasonable explanation for these extinctions. Based on the identification of changes in keystone species in Mallorcan ecosystems, we propose a tentative schedule of key ecological changes that have taken place over the past 5 millennia.     

Karyological observations on plant taxa endemic to the Balearic Islands

Mitotic chromosome numbers are reported from 35 vascular plant taxa endemic to the Balearic Islands that are poorly known cytogenetically. The chromosome numbers of Chaenorhinum rodriguezii (2 n  = 14), Coristospermum huteri (2 n  = 22), Carduus ibicensis (2 n  = 26), Filago petro-ianii (2 n  = 26), Ononis crispa ssp. zschackei (2 n  = 30), and Ophrys bertolonii ssp. balearica (2 n  = 36) were determined for the first time. New chromosome numbers are reported in Pimpinella bicknellii (2 n  = 22), Calamintha rouyana (2 n  = 46), Vicia bifoliolata (2 n  = 14), and Teucrium asiaticum (2 n  = 30). A new diploid cytotype (2 n  = 16) was found in Ranunculus paludosus ssp. barceloi , which is restricted to populations from the western Balearics (Eivissa and Formentera), whereas tetraploid plants are known from the eastern Balearics (Mallorca). It is suggested that the tetraploid cytotype arose from the diploid cytotype through autopolyploidy. The idiograms of Coristospermum huteri , Pastinaca lucida , Pimpinella bicknellii , Carduus ibicensis , Helianthemum scopulicolum , Helichrysum crassifolium , Vicia bifoliolata , p aeonia cambessedesii , Helleborus lividus , Ranunculus paludosus ssp. barceloi , and Linaria aeruginea ssp. pruinosa are determined for the first time.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 463–476.     

An impact assessment of the alien lizard Plestiodon japonicus (Scincidae, Reptilia) on a threatened island population of the native lizard P. latiscutatus at an early phase of the biological invasion

On the island of Hachijojima, central Japan, a formerly abundant population of native lizard, Plestiodon latiscutatus has become endangered by predation from an alien weasel (Mustela itatsi). Recently, an alien lizard, P. japonicus, became established on the island. The impact of the alien lizard and current distribution of the native lizard were assessed by field surveys and DNA analyses. The native lizard was sparsely distributed in the western part of the island. The alien lizard occurred in the northeastern region of the island. Between these regions, several hybrid populations were identified, including some with non-F1 genotypes, suggesting that introgression is occurring. The distribution of the weasel was examined based on field observations, allowing us to estimate predator impacts on both lizard species. We found evidence that the weasel was present throughout the entire island, suggesting that the alien lizard was able to become established despite the presence of the weasel. This indicates that the alien lizard is likely to expand its habitat range and that introgression may spread. We conclude that P. latiscutatus populations will become increasingly endangered by the synergism of genetic introgression from P. japonicus and predation pressure from the weasel.     

The taxonomy of Galium crespianum J.J. Rodr. (Rubiaceae), a Balearic Islands endemic revisited

Galium crespianum J.J. Rodr. is a perennial plant inhabiting cliffs and crevices on the Balearic Islands. Although it was described from the mountains of Mallorca, several populations from the islands of Eivissa and Formentera have been traditionally considered as belonging to the same species. A careful comparison of specimens from the western and eastern Balearics revealed several discriminant features in gross morphology (robustness and habit of the stems, presence or absence of hairs at the internodes and leaves, waxiness of stems and leaves, shape of the inflorescence, flower colour and scent) and stem anatomy. In addition, several mutations in the ribosomal ITS sequences distinguished western and eastern plants. It is proposed that the plants from Eivissa and Formentera previously subsumed under G. crespianum be recognized at the specific level as G. friedrichii N. Torres, L. Saez, Mus & Rossello nom. nov. The new species is tetraploid (2n = 44) and shares morphological features with G. crespianum or with several taxa in the G. glaucum complex from the south east Iberian peninsula, to which it is most probably related.     

Spargana in a Weasel,Mustela sibirica manchurica,and a Wild Boar,Sus scrofa,from Gangwon-do,Korea

To know the status of sparganum (plerocercoid of Spirometra erinacei) infection in the Korean wild life, several species of wild animals were captured in Gangwon-do and examined for their status of infection with spargana. From February to December 2011, a total of 62 wild boars, 5 badgers, 1 weasel, 1 Siberian chipmunk, and 53 wild rodents were captured, and their whole muscles were examined with naked eyes for the presence of spargana worms. From the weasel and 1 wild boar, a total of 5 spargana specimens were extracted. The weasel was for the first time recorded as an intermediate or paratenic/transport host of S. erinacei in Korea, and both the weasel (Mustela sibirica manchurica) and wild boar (Sus scrofa) were added to the list of wild animals carrying spargana.     

Translocation of Photosynthates in Tall and Dwarf Varieties of Pea, Pisum sativum

Quantitative studies of the translocation of radiocarbon from a young expanded leaf of two tall varieties (Improved Pilot and Thomas Laxton) and two dwarf varieties (Little Marvel and Meteor) of Pisum sativum showed that 40 to 45 per cent of the radiocarbon was exported from the ¹⁴CO₂ treated leaf after 24 hours in all four varieties. Although substantial export to the upper shoot always occurred it was more marked in the two tall varieties. Pre-treatment with GA did not affect total fixation but increased total export from the ¹⁴CO₂ treated leaf in cv. Meteor and decreased it in cv. Improved Pilot. GA had no effect on the translocation pattern in the tall plants but modified that of the dwarf plants to correspond to that found in the tall varieties.     

New data on the origin of Nesiotites (Soricidae,Mammalia) in Menorca (Balearic Islands,Spain)

The presence of the shrew Nesiotites in Menorca is not yet adequately explained. Some authors consider that its ancestor arrived during the Messinian Salinity Crisis, as happened in Mallorca. Other authors consider that fossil populations in Menorca are the result of a later migration from Mallorca. In this work, several biometrical and morphological characters of abundant fossil populations from both islands have been studied. The results indicate that Early Pleistocene populations in Mallorca and Menorca are rather indistinguishable. Therefore, an early post-Messinian (Pliocene) isolation of Nesiotites in both islands is quite unlikely.     

First evidence of faunal succession in terrestrial vertebrates of the Plio-Pleistocene of the Balearic Islands,western Mediterranean

Terrestrial vertebrates from the karst filling in Cap d’Artrutx, situated in the extreme Southwest of Menorca (Balearic Islands, western Mediterranean) have yielded interesting information on the migration and extinction dynamics in the terrestrial island vertebrate faunas in Mallorca and Menorca between the late Pliocene and early Pleistocene. In this site, remains of the Menorcan giant tortoise (“Testudo” gymnesica Bate, 1914) and two mammals (Nesiotites sp. and Hypnomys sp.) have been found. The remains of the Menorcan giant tortoise represent the youngest record of this species and of the so-called second faunistic group of the island. The morphology and size of Nesiotites sp. are comparable to those of Nesiotites aff. ponsi Reumer, 1979 from the Plio-Pleistocene of Pedrera de S’Ònix (Mallorca) and Nesiotites meloussae Pons and Moyà, 1980 (= Nesiotites aff. ponsi sensu Pons-Monjo et al., 2012) from the lower Pleistocene of Binigaus (Menorca). Hypnomys sp. can belong to an archaic species not yet described. They represent the first evidence of the entrance of the third faunistic group, which originally evolved on the neighbouring island of Mallorca. This association is interpreted, therefore, as the first evidence of a faunal succession in the Plio-Pleistocene in the Balearic Islands.     

Los mamíferos insulares del Mioceno medio y superior de Menorca (islas Baleares, Mediterráneo occidental)

The insular mammals from the karstic deposits of Punta Nati-2 and the marine beds of es Cul de sa Ferrada, placed in the northwest coast of Minorca (Balearic islands, Spain, western Mediterranean) are described in this work. One of the mammals (only present in Punta Nati-2) is a new glirid species, Margaritamys adroveri, closely related with Margaritamys llulli Mein and Adrover, 1982 and Pseudodryomys granatensis Agustí, 1993, from the middle Miocene of Santa Margalida and Sant Llorenç (Mallorca) and Murchas (Granada), respectively. M. adroveri shows more derived characters than P. granatensis and is more archaic than M. llulli, the size being similar to P. granatensis. The ochotonid present in Minorca is very similar to Gymnesicolagus gelaberti Mein and Adrover, 1982 from Mallorca. In the two minorcan deposits were recovered the first mandibles of this ochotonid, characterized by their big size. The medium weight (estimated from the length of the lower row) for G. aff. gelaberti is 5.4 kg, very similar to that some extant leporids like Lepus alleni Mearns, 1890 or Lepus arcticus Ross, 1819 and higher than any other living ochotonid. Doubtless, the big size of G. aff. gelaberti is a consequence of insular evolution, but not the short diastema, a primitive character shared with continental ochotonids and insular leporids. The discovery of a mandible in the marine beds of es Cul de sa Ferrada permits to place G. aff. gelaberti in the lower Tortonian, which represents the youngest record for this species with respect the faunal associations of Mallorca and Granada, Langhian-Serravalian in age (middle-upper Miocene). The fauna from Punta Nati-2 may represent an endemic association or a faunal group closely related to the fauna of Mallorca and Granada, but in an older context. The age of Gymnesicolagus and the presence of a similar fauna in Mallorca and Minorca suggest a connection between both islands during the Serravalian and the existence of an emerged area in Minorca after the Tortonian transgression.     

Neoplasia in the Siberian weasel (<Emphasis Type="Italic">Mustela sibirica</Emphasis>): two case reports of fibrosarcoma and interstitial cell tumour

Two cases of neoplasia occurred in two adult Siberian weasels (Mustela sibirica) in a game reserve in southern Lower Saxony, Germany. The first case, a male weasel, showed an enlargement of the right testicle, which was surgically removed. The tumour was classified as an interstitial cell tumour. One year after surgery, the male weasel died by accident and revealed tumour lesions of uncertain histogenesis within the abdominal cavity and the spleen at necropsy. The second case, a female animal, became suspicious by a dermal mass in the upper left hind limb, which was also surgically excised. Pathological examinations revealed a fibrosarcoma that recurred twice after removal of the original mass. These two cases of neoplasia in the Siberian weasel are demonstrated with regard to clinical aspects and discussed on the basis of their pathomorphological features.     

Fossils and phylogeny uncover the evolutionary history of a unique antipredator behaviour

Recently, two squirrel species (Spermophilus spp.) were discovered to anoint their bodies with rattlesnake scent as a means of concealing their odour from these chemosensory predators. In this study, we tested multiple species with predator scents (rattlesnake and weasel) to determine the prevalence of scent application across the squirrel phylogeny. We reconstructed the evolutionary history of the behaviour using a phylogenetic analysis and fossil records of historic predator co‐occurrence. Squirrels with historical and current rattlesnake co‐occurrence all applied rattlesnake scent, whereas no relationship existed between weasel scent application and either weasel or rattlesnake co‐occurrence. This was surprising because experimental tests confirmed rattlesnake and weasel scent were both effective at masking prey odour from hunting rattlesnakes (the primary predator of squirrels). Ancestral reconstructions and fossil data suggest predator scent application in squirrels is ancient in origin, arising before co‐occurrences with rattlesnakes or weasels in response to some other, now extinct, chemosensory predator.     

Effects of temporal variation in the risk of predation by least weasel (Mustela nivalis) on feeding behavior of field vole (Microtus agrestis)

Predation risk tends to vary in time. Thus prey animals face a problem of allocating feeding and antipredator effort across different risk situations. A recent model of Lima and Bednekoff (1999) predicts that a prey should allocate more feeding effort to low risk situations and more antipredator effort to high risk situations with increasing relative degree of risk in high risk situations (attack ratio). Furthermore when the proportion of time the prey spends in the high risk situation (p) increases, the prey have to eventually feed also in the high risk situations. However the increase in feeding effort in low risk situations should clearly exceed that in high risk situations as p increases. To test these predictions we measured feeding effort of field voles (Microtus agrestis) exposed to varying presence of least weasel (Mustela nivalis) and its feces in laboratory conditions. We generated quantitative predictions by estimating attack ratios from results of a pilot experiment. The model explained 15% of the observed variation in feeding effort of voles. Further analyses indicated that feeding effort was lower in high risk situations than in low risk situations at high attack ratio, but not at a lower one. Voles exposed to a presence of a weasel for extended periods showed signs of nutritional stress. Still we did not find any increase in feeding effort with increasing p. This was obviously due to the relatively low maximal p we used as we included only conditions likely to occur in nature.     

No evidence of past bottlenecks in two Danish mustelids: results of craniometric and genetic studies in time and space

A craniometric and molecular genetic investigation was conducted in Danish stoat (Mustela erminea) and weasel (Mustela nivalis) populations. Specimens used were collected over a wide time span (stoat: 1864–2002; weasel: 1863–1990) and from several geographical regions (Jutland peninsula and the two islands of Funen and Zealand). The study was made with a temporal and a spatial perspective, allowing the estimation of differences in genetic diversity and craniometrical trait means between geographical regions and through time with the use of ancient DNA techniques. Univariate statistics of 11 trait lengths did not reveal geographical differentiation in size and shape among the different regions for the stoat, but a geographical differentiation in shape was found for the weasel. There was evidence for reductions in skull size with the year of collection in male stoats, but not in females, which suggests that some selective pressures or environmental factors have affected male stoats to a greater extent than female stoats and the weasel. Relatively high values of heterozygosity were found in both the stoat and weasel, using microsatellite markers. The level of genetic variability of the stoat collected recently was compared with the level of genetic variability in the historical samples, demonstrating that the stoat has not suffered severe loss of genetic variability through the investigated period. A comparison of recent and historical genetic variability of the weasel was not possible because the ancient DNA extracted from the weasels was too degraded. Pairwise F_ST values and assignment tests showed small but significant genetic differentiation between the different geographical regions for both the stoat and weasel. No genetic differentiation between the recent and historical samples of the stoat was found. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88 , 541–553.     

First fossil record of Vipera Laurenti 1768 “Oriental vipers complex” (Serpentes: Viperidae) from the Early Pliocene of the western Mediterranean islands

The first fossil record of Vipera “Oriental vipers complex” (Serpentes: Viperidae) in the western Mediterranean islands is presented. Two large-sized vertebrae were found in an Early Pliocene karstic deposit located on the eastern coast of Mallorca, close to Caló den Rafelino (Manacor). The centrum length of the trunk vertebra (12.7 mm) represents the largest-sized known specimen of the European vipers belonging to the “Oriental vipers complex” and it suggests a body length close or greater than 200 cm. The arrival of this snake to Mallorca probably took place during the Messinian Salinity Crisis of the Mediterranean Sea (Late Miocene, 5.6-5.32 My ago) and it should be considered as one of the largest predators in Mallorca during the Early Pliocene. Although patterns of body size change in island snakes are unclear, some considerations about the large size of the Caló den Rafelino viper and co-evolution with endothermic preys are proposed.     

Presence of Hypolagus Dice, 1917 (Mammalia, Lagomorpha) in the Neogene of the Balearic Islands (Western Mediterranean): Description of Hypolagus balearicus nov. sp.

In this paper we describe a new species of Hypolagus coming from an early Pliocene karstic deposit near Caló den Rafelino (Manacor, Mallorca). It represents the westernmost European record for the genus. The faunal assemblage of this deposit represents an early phase of the second insular faunal episode of Mallorca, related with the Messinian regressive episode (latest Miocene). Although the postcranial are relatively robust, the size of all these elements is included in the range of continental leporids. It is unknown if they display significant allometric changes, as occurred in other insular leporids. p3 is small and displays a markedly trapezoidal outline and a deep hypoflexid (between 54 and 56% of the total tooth width). The presence of Hypolagus in the Neogene of the Balearic Islands is in agreement with the faunal scenario for the European continent during the late Miocene and the Pliocene, where this genus is abundant and widely distributed.     

A review on the effects of alien rodents in the Balearic (Western Mediterranean Sea) and Canary Islands (Eastern Atlantic Ocean)

Invasions of alien rodents have shown to have devastating effects on insular ecosystems. Here we review the ecological impacts of these species on the biodiversity of the Balearic and the Canary Islands. A total of seven species of introduced rodents (two rats, three mice, one dormouse, and one squirrel) have been recorded (six in the Balearics and four in the Canaries). Some of them can occasionally be important predators of nesting seabirds, contributing to the decline of endangered populations in both archipelagos. Rats are also known to prey upon terrestrial birds, such as the two endemic Canarian pigeons. Furthermore, rats actively consume both vegetative and reproductive tissues of a high number of plants, with potential relevant indirect effects on vegetation by increasing erosion and favoring the establishment of alien plants. In the Balearics, rats and mice are important seed predators of endemic species and of some plants with a restricted distribution. In the Canaries, rats intensively prey upon about half of the fleshy-fruited tree species of the laurel forest, including some endemics. In both archipelagos, alien rodents disrupt native plant–seed dispersal mutualisms, potentially reducing the chances of plant recruitment at the same time that they modify the structure of plant communities. We further suggest that alien rodents played (and play) a key role in the past and present transformation of Balearic and Canarian native ecosystems.     

Behavioral and neuroendocrine response of Brandt's voles,Lasiopodomys brandtii,to odors of different species

Predator odors are nonintrusive natural stressors of high ethological relevance. Behavioral and hormonal responses and changes in the expression of medial hypothalamic c-fos mRNA were examined in Brandt's voles (Lasiopodomys brandtii) after exposure to feces of a domestic cat (Felis catus), weasel (Mustela sibirica), snake (Xenopeltis hainanensis), goat (Capra aegagrus), and distilled water (control). One hundred voles were tested in the defensive withdrawal apparatus. Voles showed an aversion to the predator odors by showing significant high levels of flight-related behaviors, more freezing behavior, and less and higher grooming behavior when they exposed to weasel and cat feces and more vigilant rearing compared to goat and control groups. Adrenocorticotropic hormone and corticosterone serum levels significantly increased when voles were exposed to the predator odors compared to voles exposed to goat and control odors. A significant high c-fos mRNA level indicates a strong predator odor-induced activation of the medial hypothalamus of the tested voles. Our results display significant fear responses of Brandt's voles exposed to predator odors and that they can skillfully differentiate between odors from different species with odors from sympatric predators triggering the highest responses.     

High resolution bomb dating for testing the accuracy of age interpretations for a short-lived pelagic fish, the Atlantic herring

Although stock assessments of Atlantic herring (Clupea harengus harengus) in the northwest Atlantic have relied on tens of thousands of annual age determinations each year for more than 20 years, recent analyses have suggested that there may have been systemic ageing error. Tracking of dominant year-classes and otolith exchanges confirmed the presence of substantial ageing bias among some readers, although these approaches could not be used to identify an accurate set of ages (if any). We applied bomb radiocarbon in a high resolution dating approach targeted at the 1962 year-class to assess ageing accuracy by multiple age readers and laboratories. Although bomb radiocarbon age validation studies are typically restricted to long-lived species, the availability of archived otoliths through the 1960s and 1970s made herring an ideal candidate for an approach targeted at a single year-class, and allowed the extent of any ageing error to be quantified. The results clearly demonstrated that current age reading practices under-aged fish >6 yr of age by up to 45%, although younger fish were aged accurately. Age underestimation was due to incorrect annulus interpretation rather than non-annual otolith growth. By focusing on the period of most rapid radiocarbon increase (1962), the margin of uncertainty around the targeted bomb radiocarbon ages was reduced to 0.66 yr. This study represents the first time the bomb dating method has reached sub-annual accuracy, which makes it well suited to the age validation of short lived fish species. The use of the targeted approach has considerable promise for improving the accuracy of other bomb radiocarbon studies without the problematic assumptions associated with curve estimation and environmental effects.     

PATTERNS OF CARBON ALLOCATION IN AN ARCTIC TUNDRA GRASS,DUPONTIA FISCHERI (GRAMINEAE), AT BARROW,ALASKA

In Dupontia fischeri R. Br. the pattern of translocation of photosynthetically incorporated ¹⁴C was established within six hr after treatment in situ at Barrow, Alaska. More radiocarbon went to younger rather than older tillers. The most effective sinks were root, lateral root, and rhizome primordia and nonemergent tillers which were actively growing. Substantial amounts of radiocarbon appeared in the stem base and rhizome of the treated tiller. Although relatively little appeared in other plant parts, except for the sinks mentioned above, interdependence of tillers appeared to be maintained until flowering occurred. This pattern of distribution was established early in the season once the soil thawed, and growth began and was maintained until mid-August. Some translocation to active growth centers occurred even while the soil was thawing. Redistribution of radiocarbon to new root and leaf tissues produced after the time of treatment was observed. There was no autoradiographic evidence during the season to indicate storage of large amounts of mobilizable photosynthate in the stem base or rhizome of a tiller at the time these field studies were carried out.     

Notes on the Weasel in Historic Plains Indian Culture

Abstract

One of the smaller mammals of the Creat Plains is the short-legged, slender-bodied, agile and aggressive weasel. The historic Indian tribes of this region did not eat the weasel, but the northern tribes snared these animals in winter to obtain their handsome white pelts. Winter weasel pelts were coveted items in both intratribal and intertribal trade and were used by many tribes to decorate war bonnets, and the finest men’s shirts and leggings. Whole weasels were sometimes tied to shields as war medicine, and some Siouan tribes carv, ed representations of the weasel at the ends of their wooden war clubs. Among the Plains Indians the association of the weasel with warriors’ clothing and weapons appears to have been derived from their recognition of the fighting qualities of the weasel.