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Mosaic Evolution (mosaic + evolution)

Distribution by Scientific Domains

Life Sciences	40%

Selected Abstracts

Middle Jurassic Coptoclavidae (Insecta: Coleoptera: Dytiscoidea) from China: a Good Example of Mosaic Evolution

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2010
WANG Bo
Abstract: Adults of the aquatic coptoclavid beetles (Coleoptera: Adephaga: Dytiscoidea), described from four Middle Jurassic fossil localities in Inner Mongolia and Liaoning in northeastern China, are attributed to Daohugounectes primitives Wang, Ponomarenko and Zhang, 2009, which was previously proposed after study of larvae. The generic name Timarchopsis Brauer, Redtenbacher and Ganglbauer, 1889 is proposed as a substitute for the preoccupied and junior homonym Necronectes Ponomarenko, 1977, non Milne-Edwards, 1881. Furthermore, the subfamily name Necronectinae Ponomarenko, 1977 is substituted by the available name Timarchopsinae. Daohugounectes is placed into Timarchopsinae because its adults have long, slightly apically widened tibiae and small femoral plates. The adults of this genus differ from those of other Timarchopsinae in the following features: antennae short and widened in the middle part; basal segments of protarsi not cut apically; metaventrite with a triangular plate. The larvae look like somewhat primitive forms in the subfamily Timarchopsinae. In contrast to these primitive larvae, the adults with some advanced characters can be regarded as among the most advanced forms in the subfamily Timarchopsinae, and probably represent a transition between the Timarchopsinae and Charanoscaphinae. Such mosaic evolution within Daohugounectes indicates that the evolutionary process of aquatic beetles is far more complex than previously thought. [source]

Mandibles and molars of the wood mouse, Apodemus sylvaticus (L.): integrated latitudinal pattern and mosaic insular evolution

JOURNAL OF BIOGEOGRAPHY, Issue 2 2007
Sabrina Renaud
Abstract Aim, The distinct nature of island populations has traditionally been attributed either to adaptation to particular insular conditions or to random genetic effects. In order to assess the relative importance of these two disparate processes, insular effects were addressed in the European wood mouse, Apodemus sylvaticus (Linnaeus, 1758). Location, Wood mice from 33 localities on both mainland and various Atlantic and western Mediterranean islands were considered. This sampling covers only part of the latitudinal range of A. sylvaticus but included the two main genetic clades identified by previous studies. Islands encompass a range of geographical conditions (e.g. small islands fringing the continent through large and isolated ones). Methods, The insular syndrome primarily invokes variations in body size, but ecological factors such as release from competition, niche widening and food availability should also influence other characters related to diet. In the present study, the morphology of the wood mice was quantified based on two characters involved in feeding: the size and shape of the mandibles and first upper molars. The size of the mandible is also a proxy for the body size of the animal. Patterns of morphological differentiation of both features were estimated using two-dimensional outline analysis based on Fourier methods. Results, Significant differences between mainland and island populations were observed in most cases for both the mandibles and molars. However, molars and mandibles displayed divergent patterns. Mandible shape diverged mostly on islands of intermediate remoteness and competition levels, whereas molars exhibited the greatest shape differentiation on small islands, such as Port-Cros and Porquerolles. A mosaic pattern was also displayed for size. Body and mandible size increased on Ibiza, but molar size remained similar to mainland populations. Mosaic patterns were, however, not apparent in the mainland populations. Congruent latitudinal variations were evident for the size and shape of both mandibles and molars. Main conclusions, Mosaic evolution appears to characterize insular divergence. The molar seems to be more prone to change with reduced population size on small islands, whereas the mandible could be more sensitive to peculiar environmental conditions on large and remote islands. [source]

Differential correlates of diet and phylogeny on the shape of the premaxilla and anterior tooth in sparid fishes (Perciformes: Sparidae)

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2004
M. Linde
Abstract We explore the correlational patterns of diet and phylogeny on the shape of the premaxilla and anterior tooth in sparid fishes (Perciformes: Sparidae) from the western Mediterranean Sea. The premaxilla is less variable, and in spite of the presence of species-specific features, a common structural pattern is easily recognizable in all species (i.e. the ascending and the articular processes are fused in a single branch, as in many percoid fishes). In contrast, tooth shape is more variable, and different structural types can be recognized (e.g. canine-like or incisive). Coupling geometric morphometric and comparative methods we found that the relationship between shape, diet and phylogeny also differs between premaxilla and tooth. Thus, the shape of the premaxilla is significantly correlated with food type, whereas the shape of the teeth is not correlated with diet, and probably reflects the species phylogenetic relationships. Two biological roles, resistance against compressive forces generated in the buccal cavity and the size of the oral gape, would explain the ecomorphological patterns of the premaxilla. The premaxilla and anterior tooth appear to evolve at different rates (mosaic evolution) and represent an example of morphological traits belonging to the same functional unit but following uncoupled evolutionary pathways. [source]

Mandible morphology, dental microwear, and diet of the extinct giant rats Canariomys (Rodentia: Murinae) of the Canary Islands (Spain)

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010
CYRIL FIRMAT
An ecomorphological approach of mandible shape through Fourier analyses combined with a paleodietary analysis of dental microwear patterns is used to reconstruct the diet of the extinct endemic Canariomys bravoi Crusafont, Pairó & Petter, 1964 and Canariomys tamarani López-Martínez & López-Jurado, 1987. These two large rodents, respectively, lived on Tenerife and Gran Canaria, the central islands of the Canarian Archipelago. Mandible shape and dental microwear respectively inform us on the volume of vegetal matter and on the presence of grass in the diet. Both Canariomys, which are of similar size, possess relatively similar mandible outlines and microwear patterns. For each species, a diet based on plant materials except grass is the most likely. Such results chime with the similar environments offered by the islands in which the species lived. On the contrary, molar morphology suggests different feeding habits of the two Canariomys. Thus, this suggests a case of mosaic evolution between teeth and mandibles, as well as the likely sensitivity of mandible shape to a combination of ecological and allometric factors. These new data obtained from the fossil record underline the propensity of island endemic mammals to yield surprising examples of phenotypic evolution. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 28,40. [source]