Population genetics of the black ant Formica lemani (Hymenoptera: Formicidae)

Colony kin structure and spatial population structure were studied in multiple populations of the ant Formica lemani , using allozymes and DNA microsatellites. Average genetic relatedness between nestmate workers varied little between populations ( r  = 0.51–0.76), indicating that the average colony kin structure was relatively simple. Worker genotypes could not be explained with a single breeding pair in all nests, however, and the distribution of relatedness estimates across nests was bimodal, suggesting that single- and multi-queen colonies co-occur. We studied spatial population structure in a successional boreal forest system, which is a mixture of different aged habitats. Newly clear-cut open habitat patches are quickly colonized by F. lemani , where it is able to persist for a limited number of generations. Newly-founded populations showed signs of a founder effect and spatial substructuring, whereas older populations were more homogenous. This suggests that new populations are founded by a limited number of colonizers arriving from more than one source. Genetic differentiation among local populations was minor, indicating strong migration between them. There were, however, indications of both isolation by distance and populations becoming more isolated as habitat patches grew older.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 247–258.     

Vegetative morphology and trait correlations in 54 species of Commelinaceae

The morphospace of 54 species of Commelinaceae from nine genera was examined with simultaneous attention to constraints, adaptive hypotheses and relatedness. Eleven morphological traits, including leaf length and width, angle between the leaves and internode distances, were measured for each species and analysed by principal components analysis and nested analysis of variance. The results revealed a significant signal of relatedness in vegetative morphology; genus explained 20–50% of the variance in a single trait. The relationships between some traits are consistent with adaptive explanations. The findings are consistent with the prediction that evolution for optimal phyllotaxis should be relaxed as self‐shading decreases, and that light availability governs leaf size and branching patterns. Constraints potentially explain some trait correlations, and support was found for the hypothesis that structural constraints govern leaf size and internode size correlations. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 257–268.     

Mitochondrial DNA polymorphisms of the house mouse Mus musculus domesticus from Greece, focusing on the Robertsonian chromosomal system of north-west Peloponnese

This study focused on the sequence variation in a mitochondrial region in house mice Mus musculus domesticus from chromosomally variable populations in the north-west Peloponnese, Greece. The mitochondrial molecular variation revealed was among the highest found so far for M. m. domesticus populations. The haplotype distribution pattern was rather complex. There was no clear differentiation between the populations characterized by Robertsonian chromosomes and standard all-acrocentric populations. There is therefore no indication that the Robertsonian populations were formed during a prolonged period of geographical isolation.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 643–651.     

Geographical variation in floral traits of the tree tobacco in relation to its hummingbird pollinator fauna

Nicotiana glauca , a hummingbird pollinated plant, exhibits geographical variation in several floral traits. We examined whether geographical differentiation occurred for different flower characters and if this differentiation could be explained, at least in part, by the existence or abundance of different hummingbird species in the respective pollinator assemblages. The comparison between five populations showed significant variation in six floral traits and two female fitness measures. The traits that better discriminated between populations were corolla length and corolla width. There were metric correlations between corolla length and style length in all populations studied and, in four of the five populations, both corolla length and width were also correlated. Among plants in each population, seed weight was correlated positively and significantly with style exertion, suggesting that fruit quality is dependent on the degree of cross pollination. Assemblages of hummingbirds differed between populations in species composition, visitation frequencies, and bill length. Linear regression involving bill length of the more frequent hummingbird pollinators and corolla length yielded positive and significant relationships. Thus, there appears to be an adjustment between pollinators and flowers traits that have high incidence in the among population variation.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 657–667.     

Infraspecific variation and phylogeography of the high-polyploid Iberian endemic Anthoxanthum amarum Brot. (Poaceae; Pooideae) assessed by random amplified polymorphic DNA markers (RAPDs) and morphology

High morphological and ecological diversity has been observed in the north-west Iberian Peninsula endemic Anthoxanthum amarum Brot., for which two different morphotypes (northern and southern) have been described on the basis of qualitative traits and geographical origin. In the present study, a combined molecular and morphological method was applied to ten populations of this species with the following aims: (1) to assess whether the variation observed was taxonomically meaningful; (2) to assess the influence of the environment on the variation in the morphological characters; and (3) to track the potential phylogeographical information deduced from our random amplified polymorphic DNA marker (RAPD) data in order to draw inferences about the past history of this species in the north-west Iberian Peninsula. To achieve these aims, 26 macromorphological characters were recorded in 279 specimens, and 77 RAPD phenotypes were identified in the 79 plants studied. The association analyses performed using the morphological and molecular data showed that no clear separation existed between the morphs, and a strong correlation between qualitative characters and the environment was detected. Moreover, both the multivariate analyses and the assignment test based on RAPD data revealed that the genetic variation was hierarchically structured, and three genetically distinct groups could be identified. Two of these clusters might correspond to different expansion routes proposed in the literature for different plant species in the north-west Iberian Peninsula.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 179–192.     

Morphotypes,varieties, or subspecies?: genetic diversity and differentiation of four Saintpaulia (Gesneriaceae) morphotypes from the East Usambara Mountains,Tanzania

Saintpaulia (H. Wendl.) is a forest-dependent, endangered plant genus endemic to Tanzania and Kenya. The taxonomy of Saintpaulia from the Usambara Mountains and adjacent lowlands in north-eastern Tanzania is problematic because of the morphological similarity of the species and the presence of considerable intraspecific variation. Conventional molecular phylogenetic methods have failed to reveal the genetic structure of this Saintpaulia complex. In this study, we assessed the genetic composition of 12 Saintpaulia populations, representing four different morphotypes, from the East Usambara Mountains using inter-simple sequence repeat (ISSR) markers. Relatively high genetic diversities were observed within populations (mean h  = 0.320), indicating their adaptive potential. Little genetic differentiation amongst populations (mean F _st  = 0.063) and the genetic divergence of the rosulate and trailing morphotypes support the hypothesis of ongoing divergent evolution within the East Usambara metapopulation(s) of Saintpaulia .  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 347–355.     

Cytogenetics, geographical distribution, and pollen fertility of diploid and tetraploid cytotypes of Santolina pectinata Lag. (Asteraceae: Anthemideae)

A cytogenetic study of 62 populations of Santolina pectinata in Spain shows the existence of two ploidy levels. The diploid cytotypes with 2 n  = 18 occupy the eastern Betic mountains, and the tetraploid cytotypes with 2 n  = 36 are located on the spurs of the Iberian System. The former show a much wider ecological spectrum than the latter. Mixed cytotypes were observed in two diploid populations, with one tetraploid in each, showing different karyotypes. Three trisomic individuals were detected, one in a diploid population and the other two in a tetraploid population. Also, three hypotetraploid individuals were detected in a tetraploid population. Polyploidy is shown to be spontaneous and recurrent, promoting partial sterility in the pollen. Structural chromosomal changes, principally translocations, and local speciation through autopolyploidy are the principal factors in the evolution and diversification of this species.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 657–667.     

Genetic and morphological differentiation patterns between sister species: the case of Onthophagus taurus and Onthophagus illyricus (Coleoptera, Scarabaeidae)

The present study investigated the morphological and genetic differentiation pattern between two sympatric dung beetle sister species, Onthophagus taurus and Onthophagus illyricus . The geometric morphometric approach coupled with the use of molecular markers allowed examination of the nature of interspecific relationships and an outline of the evolutionary and geographical processes that might have led to interspecific differentiation and the present-day partial sympatric and syntopic pattern of distribution. Geometric morphometrics failed to discrimininate the two species on the ground of external morphological traits, but revealed interspecific differences when the shape of the primary sexual traits was taken into account. The use of two different molecular markers (cytochrome oxidase subunit I gene and amplified fragment-length polymorphism) demonstrates that the two species are genetically well differentiated, forming two distinguishable lineages probably diverged during the Pliocene by allopatric speciation. No evidence of past or recent introgression and no support for hybridization were found, suggesting that sympatry was established subsequently, when speciation was accomplished. Both molecular markers and genital shape indicate that phenotypically intermediate individuals, despite their ambiguous appearance, are members of O. illyricus species rather than hybrids.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 197–211.     

Morphological, mitochondrial DNA and allozyme evolution in representative amphibians and reptiles inhabiting each side of the Strait of Gibraltar

Patterns of differentiation in morphology, mitochondrial DNA and allozymes in amphibians and reptiles inhabiting northern and southern shores of the Strait of Gibraltar are not concordant, suggesting that each taxon was affected differently by events preceding or following the formation of the Strait of Gibraltar. Mitochondrial DNA and allozyme differentiation between Discoglossus jeanneae and Discoglossus scovazzi (Anura, Discoglossidae), Rana perezi and Rana saharica (Anura, Ranidae), and Blanus cinereus and Blanus tingitanus (Squamata, Amphisbaenia, Amphisbaenidae) is substantial, whereas morphological differentiation is moderate in Rana and Blanus , but is substantial in Discoglossus . Differentiation in mitochondrial DNA and morphology between Timon ( Lacerta ) lepidus and Timon ( Lacerta ) tangitanus (Squamata, Lacertoidea, Lacertidae) is considerable, but allozyme differentiation is low. In members of type-I and -II Podarcis vaucheri (Squamata, Lacertoidea, Lacertidae), morphology and mitochondrial DNA are moderately differentiated, but allozyme differentiation is low. Spanish and Moroccan populations of Hyla meridionalis (Anura, Hylidae), Mauremys leprosa (Testudines, Geoemydidae), and Macroprotodon brevis (Squamata, Serpentes, Colubridae) demonstrate little allozyme and mitochondrial DNA differentiation, but whereas morphological differentiation between Mauremys and Macroprotodon populations is moderate, Hyla demonstrate substantial morphological differentiation between continental populations. These data suggest that sex-limited mitochondrial markers are reflective of ancient phylogenetic history, whereas biparentally inherited allozyme markers and morphological characteristics reflect more recent population structure and movement.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 445–461.     

Geographical variation and diversification in the flightless leaf beetles of the Chrysolina angusticollis species complex (Chrysomelidae, Coleoptera) in northern Japan

Geographical variation and differentiation of flightless leaf beetles of the Chrysolina angusticollis species complex were analysed. Nine morphological groups were recognized on the basis of metric characters relating to body size, shape of hind wing and shape of male genitalia, and binary characters relating to females' elytral surface and larval pubescence. The nine groups were essentially parapatric or allopatric to each other. Five groups occupied a continuous geographical range each, whereas another four groups were disjunctively distributed. Morphometric distance and geographical distance between populations were significantly correlated. Analyses based on 13 allozyme loci demonstrated that six out of the nine morphological groups were further divided into more than one genetically distinct group each. Genetic similarity between populations was significantly correlated with morphometric similarity and geographical closeness. Disjunctively distributed populations of a single morphological group more often resembled geographically adjacent populations of different morphological groups than geographically remote populations of the same group. In a morphological group that occupied a wide continuous range, remote populations substantially differed genetically from each other. The results suggest that there exist at least 19 morphologically and/or genetically differentiated units in the C. angusticollis complex in northern Japan. The C. angusticollis complex is likely a superspecies composed of a number of semispecies. We postulate that the diversification of this species complex might have resulted from the repeated range contraction and expansion during the ice ages. Movement of tension zones that separate two adjacent forms might contribute to enhance their geographical differentiation.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 557–578.     

Comparative morphology of the dermal palate in squamate reptiles, with comments on phylogenetic implications

The differentiation of the dermal palate and of the septomaxilla in extant squamate reptiles is reviewed in terms of Lakjer's distinctions of a palaeochoanate, incomplete neochoanate, and neochoanate condition. The differentiation of the bones surrounding the mushroom body, Jacobson's organ, and the internal naris (choana) supports a number of clades including Squamata, Scleroglossa, and Autarchoglossa, with Serpentes nested within Autarchoglossa. Dermal palate morphology and the differentiation of the septomaxilla in squamates reflect the evolution of the chemosensory system in general, and the vomeronasal system in particular, and strongly contradict a recent hypothesis of squamate phylogeny based on molecular data.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 131–152.     

Morphological differentiation among closely related species with disjunct distributions: a case study of Mediterranean Cyclamen L. subgen. Psilanthum Schwarz (Primulaceae)

In Cyclamen subgenus Psilanthum , previous authors have recognized three species ( C. repandum, C. balearicum and C. creticum ), with C. repandum subdivided into three subspecies (ssp. repandum , ssp. peloponnesiacum and ssp. rhodense ), and two varieties (var. vividum and var. peloponnesiacum ) within C. repandum ssp. peloponnesiacum . To examine the validity of this classification and the degree of morphological differentiation among closely related endemic taxa with disjunct distributions, we undertook analyses of three quantitative and eight qualitative morphological traits of flowers and leaves, most of which have previously been used without statistical comparison in the classification of the different taxa. Cyclamen balearicum showed high levels of morphological differentiation from all other taxa in subgenus Psilanthum consistent with its specific status. In contrast, morphological differentiation between C. creticum and subspecies of C. repandum was similar to that among the three subspecies of C. repandum . When compared with a recent molecular phylogeny of this subgenus, our results suggest that C. creticum may best be described as a geographical subspecies of C. repandum . The two varieties of C. repandum ssp. peloponnesiacum showed few significant differences for individual traits and their overall morphology is very similar to each other. The morphology of plants at three sites on Corsica strongly suggest, consistent with molecular data, the occurrence of hybrid populations between C. balearicum (outside of its previously recognized distribution) and local C. repandum .  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 133–144.     

Genetic relatedness assessment through individual odour similarities in mice

Previous research has demonstrated that closer genetic relatedness between individuals (from kin to across species) is associated with greater similarity in the qualities of their individual odours ('odour-genes covariance'). This predictable relationship between individual genotypes and individual odours could enable animals to assess their degree of genetic relatedness to other individuals by comparing the degree of similarity between another individual's odour and their own odour. In two-choice tests with odours of unfamiliar mice from different populations and species, subjects from two species of wild mice, Mus spicilegus and M. musculus , that had been raised in mixed litters of both species spent significantly more time investigating the ano-genital odour of the more genetically similar individual. This differential interest was not affected by common rearing with heterospecifics. These responses are consistent with a self-referencing mechanism enabling differential responses across a wide spectrum of genetic relatedness from kin through populations to heterospecifics. These assessments depend on the degree of similarity between the donor's and the subject's odours rather than on differences between them. Such a parsimonious mechanism may provide a basis for differential responses to conspecifics as opposed to heterospecifics that may function as a premating isolating mechanism.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 595–603.     

Habitat-specific differences in thermal plasticity in natural populations of a soil arthropod

When populations experience substantial variation in environmental conditions, they may evolve phenotypic plasticity in response to these varying selection pressures. Evolutionary theory predicts differentiation in the level of phenotypic plasticity among different habitats. We evaluated temperature-induced phenotypic responses in juvenile growth rate in natural populations of the springtail Orchesella cincta , inhabiting forest and heathland. These habitats typically co-occur but differ strongly with respect to, for example, thermal regime, relative humidity, and structure. Offspring of females from the two habitats were reared at different temperatures in climate rooms and the temperature response of juvenile growth rate and egg size was measured. We found a habitat-specific difference in plasticity of juvenile growth rate. The reaction norms of the forest populations were steeper than the reaction norms for heath populations at two replicated sampling sites. Egg weight itself was demonstrated to be a plastic trait with a higher egg weight at low temperatures, but the thermal response did not differ between habitats. We conclude that these populations have diverged due to strong local natural selection. Our results support the argument that the level of phenotypic plasticity itself can be under selection and that differentiation in reaction norms can occur even in neighbouring habitats with no barrier to gene flow.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 265–271.     

Potential refugium on the Qinghai–Tibet Plateau revealed by the chloroplast DNA phylogeography of the alpine species Metagentiana striata (Gentianaceae)

Metagentiana striata is an alpine annual herbaceous plant endemic to the east of the Qinghai–Tibet (Q–T) Plateau and adjacent areas. The phylogeography of M. striata was studied by sequencing the chloroplast DNA (cpDNA) trn S– trn G intergenic spacer. Ten haplotypes were identified from an investigation of 232 individuals of M. striata from 14 populations covering the entire geographical range of this species. The level of differentiation amongst populations was very high ( G _ST = 0.746; N _ST = 0.774) and a significant phylogeographical structure was observed ( P  < 0.05). An analysis of molecular variance found a high variation amongst populations (76%), with F _ST = 0.762 (highly significant, P  < 0.001), indicating that little gene flow occurred amongst the different regions; this was explained by the isolation of populations by high mountains along the Q–T Plateau and adjacent areas ( N _m = 0.156). Only one ancestral haplotype (A) was common and widespread throughout the distributional range of M. striata. The populations of the Hengduan Mountains region of the south-eastern Q–T Plateau showed high diversity and uniqueness of haplotypes. It is suggested that this region was the potential refugium of M. striata during the Quaternary glaciation, and that interglacial and postglacial range expansion occurred from this refugium. This scenario was in good agreement with the results of nested clade analysis, which inferred that the current spatial distribution of cpDNA haplotypes and populations resulted from range expansion, together with past allopatric fragmentation events.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 125–140.     

High levels of genetic diversity in populations of Iris aphylla L. (Iridaceae), an endangered species in Poland

We used RAPDs (Random Amplified Polymorphic DNAs) to investigate genetic diversity and its partition within and between three populations of Iris aphylla in Poland. Analysis of Molecular Variance (AMOVA) of 84 distinct RAPD multiband genotypes revealed higher variation within populations (77.2%) than genetic differentiation between them (22.8%, P  < 0.002). Values of genetic diversity indices ( H ) were similar in all three sites (0.21–0.24). The differentiation of the populations corresponded to low average gene flow ( Nm  = 0.81). Our results indicated that genetic diversity was independent of population size. We concluded that although sexual reproduction and gene flow between populations of I. aphylla were very limited, they preserved high levels of genetic diversity. Relatively large number of seeds, which migrated in the past to populations, as well as patterns of reproduction and life history of I. aphylla may explain this situation.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 65–72.     

Local adaptation of developmental time and starvation resistance in eight Drosophila species of the Philippines

The ecological trade-off between developmental time and starvation resistance, acting in a heterogeneous environment, can promote the coexistence of competing species. Heterogeneity results from variation in the vegetation that influences both abiotic (e.g. temperature, humidity) and biotic (e.g. fruit availability during the year) aspects of the environment. In this study, we investigated whether differences between collection sites have led to local differentiation of the two life-history traits underlying the coexistence model: developmental time and starvation resistance. Drosophila were collected from four collection sites, ranging from grassland to secondary forest, along a transect of 15 km. The microclimatic and vegetation differences among these collection sites were considerable. For developmental time, different species showed similar genetic responses to the (habitat) differences between the different collection sites. The shortest developmental times were found in the secondary forest populations and the agricultural area populations, the longest in the grassland populations, and the forest edge populations were intermediate. However, there was no correlation between the habitat ranking based on disturbance and canopy cover, and the ranking of the developmental times. Furthermore, the data did not confirm the generality of the positive correlation between developmental time and starvation underlying the coexistence model.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87 , 115–125.     

Morphology of Pinus uliginosa (Pinaceae) needles from populations exposed to and isolated from the direct influence of Pinus sylvestris

Eleven needle traits of two contrasting populations of Pinus uliginosa ( P. mugo complex), one located in a Pinus sylvestris forest, the other isolated from the influence of this species, were compared to quantify the degree of hybridization. Statistically significant differences between the studied populations were found, but both of them differed by a similar degree from P. sylvestris . Surprisingly, the P. uliginosa population surrounded by the P. sylvestris forest, which was expected to consist of individuals with intermediate traits, appeared to be more closely related to P. mugo than those isolated from the direct influence of P. sylvestris . Large differences in the distances between the analysed pair of populations of P. uliginosa and P. sylvestris have not influenced the morphological traits of the species. Gene flow from P. sylvestris to P. uliginosa is possible, but is likely to be small and does not differ compared with populations of P. uliginosa . The decline observed during the last three decades in both populations of the species has not influenced their needle morphological traits.  © 2003 The Linnean Society of London , Botanical Journal of the Linnean Society , 2003, 142, 83–91.