Myotis albescens occurs from Mexico southward to Uruguay and Argentina. The species is known for ... more Myotis albescens occurs from Mexico southward to Uruguay and Argentina. The species is known for all South American countries except French Guiana and Chile. Based on one specimen recently collected in French Guiana we fill part of the gap in the distribution of the species in South America. Myotis albescens occurs in the Guiana Shield with other four congeners, from which it can be distinguished by external and skull traits. As an aid to future identifications, we provide a key to this assemblage.
The skulls of 387 shrews of the genus Crocidura sampled in peninsular Malaysia, Sumatra, Borneo, ... more The skulls of 387 shrews of the genus Crocidura sampled in peninsular Malaysia, Sumatra, Borneo, Java and Sulawesi were submitted to principal component and stepwise discriminant analyses. These analyses helped to delineate morphological taxa in this species-rich genus of mammals. Most morphologic groups could be attributed to described species, except one taxon from Sumatra and one from Sulawesi, which are described and named as new. Most of the 21 species recognized in this paper are endemic to one major island. Although Sulawesi has never been connected to the mainland, it supports at least six species, followed by Sumatra (5–6 species), Java and the Malay Peninsula (4 spp) and Borneo (3 spp). C. monticola is apparently the only widespread species whose distribution range covers the entire Malay Archipelago except the Philippines and Sulawesi. In contrast, the continental C. fuliginosa enters only marginally into the Sunda Shelf: its southernmost record is on the Malay Peninsula. This interpretation is completely different from the classical view that C. fuliginosa is a cosmopolitan species occupying the whole of Southeast Asia. Identification keys, tables of measurements and discriminant functions provided in this work may aid in identification of the various species and subspecies of Crocidura living in the Malaya Archipelago.
... review is the western part of the Malay Archipelago: it includes the Malaya Peninsula, the ma... more ... review is the western part of the Malay Archipelago: it includes the Malaya Peninsula, the major islands of the Sunda Shelf (Sumatra ... Too few reference specimens from the eastern parts of the Malay Archipelago (the Lesser Sundas and Moluccas) are presently available and will ...
Genetic variation of 20 species of shrews from the Malay peninsula, Sumatra, Java, Borneo, the Ph... more Genetic variation of 20 species of shrews from the Malay peninsula, Sumatra, Java, Borneo, the Philippines and Sulawesi was assessed by allozyme electrophoresis at 32 loci. According to Mantel's tests, the genetic differentiation of these species of shrews is not a function of the geographic distance separating them (r = 0.09, NS), but is correlated to the water depth surrounding the islands where they live (r = 0.49, P < 0.01). The results are just the reverse if the correlations are computed for the Sunda Shelf taxa only. In this case, the sampled populations show an isolation-by-distance relationship (r = 0.32; P < 0.01), while no significant correlation with water depth was detected (r = 0.20; P - 0.07). Qualitative predictions based on eustatic sea level variation and water depth were formulated as a model of historic connections between the islands. This palaeogeographic model was tested through Brooks Parsimony Analysis. The assumption of a simple vicariant evolution of the shrews was rejected, but several concordant patterns indicate that the phytogeny of these mammals was indeed shaped by these events. Homoplasies demonstrated that the SE Asian species of Crocidura include composite zoogeographic histories. Sulawesi, for example, supports at least six species, five of which are closely related, while the last one, C. nigripes, is more closely related to a Bornean taxon. This pattern was interpreted as the result of a first wave of colonizers which subsequently radiated, followed by a more recent, second colonization event from Borneo. The overall small genetic distance found within the assemblage of the five old endemics (DN= 0.151 pL 0.041) suggests that the radiation was not accompanied by extensive differentiation, although from a karyological point of view, they exhibit unusual variations when compared to other Indomalayan Crocidura. By contrast, the four species found on Sumatra are more differentiated (DN= 0.221 pL 0.063) and never form sister-group relationships in any phylogenetic reconstruction; each one is more closely related to different taxa living outside Sumatra. This suggests that they are probably remnants of an important centre of dispersal for the entire Malay Archipelago. The standard genetic distance averaged among all Southeast Asian species (DN= 0.235 pL 0.094) is about half that measured within Palearctic or African taxa. Such an overall lower mean level of genetic variability is consistent with the hypothesis of a relatively recent colonization of the Malay Archipelago by shrews of the genus Crocidura.
To the origins and evolution of Indomalayan shrews, we investigated the chromosomal variations of... more To the origins and evolution of Indomalayan shrews, we investigated the chromosomal variations of 14 species ofCrocidura from SE Asia. Intraspecific polymorphism was mainly due to variation in the number of short chromosomal arms butC. lepidura andC. hutanis showed a polymorphism due to a centric fusion. The undifferentially stained karyotypes were similar in 9 species, all possessing 2n=38 and FN=54–56 (68);C. fuliginosa had 2n=40 and FN=54–58. These karyotypes are close to the presumed ancestral state for the genusCrocidura. Four species from Sulawesi had a reduced diploid number (2n=30–34), a trend not observed among other SE Asian species but present in few Palaearctic taxa. Compared to the apparent stasis of karyotypic evolution observed among other SE Asian species, the high degree of interspecific differences reported among Sulawesian shrews is unusual and needs further investigation. Stasis and reduction in diploid number found in both Indomalayan and Palaearctic species suggest that these two groups share a common ancestry. This is in sharp contrast to most Afrotropical species which evolved towards higher diploid and fundamental numbers. The zoogeographical implications of these results are discussed.
Because of their role in limiting gene flow, geographical barriers like mountains or seas often c... more Because of their role in limiting gene flow, geographical barriers like mountains or seas often coincide with intraspecific genetic discontinuities. Although the Strait of Gibraltar represents such a potential barrier for both plants and animals, few studies have been conducted on its impact on gene flow. Here we test this effect on a bat species (Myotis myotis) which is apparently distributed on both sides of the strait. Six colonies of 20 Myotis myotis each were sampled in southern Spain and northern Morocco along a linear transect of 1350 km. Results based on six nuclear microsatellite loci reveal no significant population structure within regions, but a complete isolation between bats sampled on each side of the strait. Variability at 600 bp of a mitochondrial gene (cytochrome b) confirms the existence of two genetically distinct and perfectly segregating clades, which diverged several million years ago. Despite the narrowness of the Gibraltar Strait (14 km), these molecular data suggest that neither males, nor females from either region have ever reproduced on the opposite side of the strait. Comparisons of molecular divergence with bats from a closely related species (M. blythii) suggest that the North African clade is possibly a distinct taxon warranting full species rank. We provisionally refer to it as Myotis cf punicus Felten 1977, but a definitive systematic understanding of the whole Mouse-eared bat species complex awaits further genetic sampling, especially in the Eastern Mediterranean areas.
Myotis albescens occurs from Mexico southward to Uruguay and Argentina. The species is known for ... more Myotis albescens occurs from Mexico southward to Uruguay and Argentina. The species is known for all South American countries except French Guiana and Chile. Based on one specimen recently collected in French Guiana we fill part of the gap in the distribution of the species in South America. Myotis albescens occurs in the Guiana Shield with other four congeners, from which it can be distinguished by external and skull traits. As an aid to future identifications, we provide a key to this assemblage.
The skulls of 387 shrews of the genus Crocidura sampled in peninsular Malaysia, Sumatra, Borneo, ... more The skulls of 387 shrews of the genus Crocidura sampled in peninsular Malaysia, Sumatra, Borneo, Java and Sulawesi were submitted to principal component and stepwise discriminant analyses. These analyses helped to delineate morphological taxa in this species-rich genus of mammals. Most morphologic groups could be attributed to described species, except one taxon from Sumatra and one from Sulawesi, which are described and named as new. Most of the 21 species recognized in this paper are endemic to one major island. Although Sulawesi has never been connected to the mainland, it supports at least six species, followed by Sumatra (5–6 species), Java and the Malay Peninsula (4 spp) and Borneo (3 spp). C. monticola is apparently the only widespread species whose distribution range covers the entire Malay Archipelago except the Philippines and Sulawesi. In contrast, the continental C. fuliginosa enters only marginally into the Sunda Shelf: its southernmost record is on the Malay Peninsula. This interpretation is completely different from the classical view that C. fuliginosa is a cosmopolitan species occupying the whole of Southeast Asia. Identification keys, tables of measurements and discriminant functions provided in this work may aid in identification of the various species and subspecies of Crocidura living in the Malaya Archipelago.
... review is the western part of the Malay Archipelago: it includes the Malaya Peninsula, the ma... more ... review is the western part of the Malay Archipelago: it includes the Malaya Peninsula, the major islands of the Sunda Shelf (Sumatra ... Too few reference specimens from the eastern parts of the Malay Archipelago (the Lesser Sundas and Moluccas) are presently available and will ...
Genetic variation of 20 species of shrews from the Malay peninsula, Sumatra, Java, Borneo, the Ph... more Genetic variation of 20 species of shrews from the Malay peninsula, Sumatra, Java, Borneo, the Philippines and Sulawesi was assessed by allozyme electrophoresis at 32 loci. According to Mantel's tests, the genetic differentiation of these species of shrews is not a function of the geographic distance separating them (r = 0.09, NS), but is correlated to the water depth surrounding the islands where they live (r = 0.49, P < 0.01). The results are just the reverse if the correlations are computed for the Sunda Shelf taxa only. In this case, the sampled populations show an isolation-by-distance relationship (r = 0.32; P < 0.01), while no significant correlation with water depth was detected (r = 0.20; P - 0.07). Qualitative predictions based on eustatic sea level variation and water depth were formulated as a model of historic connections between the islands. This palaeogeographic model was tested through Brooks Parsimony Analysis. The assumption of a simple vicariant evolution of the shrews was rejected, but several concordant patterns indicate that the phytogeny of these mammals was indeed shaped by these events. Homoplasies demonstrated that the SE Asian species of Crocidura include composite zoogeographic histories. Sulawesi, for example, supports at least six species, five of which are closely related, while the last one, C. nigripes, is more closely related to a Bornean taxon. This pattern was interpreted as the result of a first wave of colonizers which subsequently radiated, followed by a more recent, second colonization event from Borneo. The overall small genetic distance found within the assemblage of the five old endemics (DN= 0.151 pL 0.041) suggests that the radiation was not accompanied by extensive differentiation, although from a karyological point of view, they exhibit unusual variations when compared to other Indomalayan Crocidura. By contrast, the four species found on Sumatra are more differentiated (DN= 0.221 pL 0.063) and never form sister-group relationships in any phylogenetic reconstruction; each one is more closely related to different taxa living outside Sumatra. This suggests that they are probably remnants of an important centre of dispersal for the entire Malay Archipelago. The standard genetic distance averaged among all Southeast Asian species (DN= 0.235 pL 0.094) is about half that measured within Palearctic or African taxa. Such an overall lower mean level of genetic variability is consistent with the hypothesis of a relatively recent colonization of the Malay Archipelago by shrews of the genus Crocidura.
To the origins and evolution of Indomalayan shrews, we investigated the chromosomal variations of... more To the origins and evolution of Indomalayan shrews, we investigated the chromosomal variations of 14 species ofCrocidura from SE Asia. Intraspecific polymorphism was mainly due to variation in the number of short chromosomal arms butC. lepidura andC. hutanis showed a polymorphism due to a centric fusion. The undifferentially stained karyotypes were similar in 9 species, all possessing 2n=38 and FN=54–56 (68);C. fuliginosa had 2n=40 and FN=54–58. These karyotypes are close to the presumed ancestral state for the genusCrocidura. Four species from Sulawesi had a reduced diploid number (2n=30–34), a trend not observed among other SE Asian species but present in few Palaearctic taxa. Compared to the apparent stasis of karyotypic evolution observed among other SE Asian species, the high degree of interspecific differences reported among Sulawesian shrews is unusual and needs further investigation. Stasis and reduction in diploid number found in both Indomalayan and Palaearctic species suggest that these two groups share a common ancestry. This is in sharp contrast to most Afrotropical species which evolved towards higher diploid and fundamental numbers. The zoogeographical implications of these results are discussed.
Because of their role in limiting gene flow, geographical barriers like mountains or seas often c... more Because of their role in limiting gene flow, geographical barriers like mountains or seas often coincide with intraspecific genetic discontinuities. Although the Strait of Gibraltar represents such a potential barrier for both plants and animals, few studies have been conducted on its impact on gene flow. Here we test this effect on a bat species (Myotis myotis) which is apparently distributed on both sides of the strait. Six colonies of 20 Myotis myotis each were sampled in southern Spain and northern Morocco along a linear transect of 1350 km. Results based on six nuclear microsatellite loci reveal no significant population structure within regions, but a complete isolation between bats sampled on each side of the strait. Variability at 600 bp of a mitochondrial gene (cytochrome b) confirms the existence of two genetically distinct and perfectly segregating clades, which diverged several million years ago. Despite the narrowness of the Gibraltar Strait (14 km), these molecular data suggest that neither males, nor females from either region have ever reproduced on the opposite side of the strait. Comparisons of molecular divergence with bats from a closely related species (M. blythii) suggest that the North African clade is possibly a distinct taxon warranting full species rank. We provisionally refer to it as Myotis cf punicus Felten 1977, but a definitive systematic understanding of the whole Mouse-eared bat species complex awaits further genetic sampling, especially in the Eastern Mediterranean areas.
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Papers by Manuel Ruedi