Interpopulation variation and selective predation in the meadow brown butterfly, Maniola jurtina (L.) (Lepidoptera: Satyridae) in the Canary Islands

Samples of the meadow brown butterfly, Maniola jurtina , were collected from all five of the Canary Islands where it occurs. The butterflies were scored for several spotting characters on both fore- and hindwings and assessed for damage from predators.
The analysis reveals considerable interisland heterogeneity for spotting characters and suggests that the populations fall into two relatively distinct, homogeneous groups, which inhabit the islands of Gran Canaria and La Gomera, on the one hand, and Tenerife, El Hierro and La Palma, on the other.
The main predators are lizards and insectivorous birds. Predator damage is non-random in the following respects: males are more damaged than females; high spot male phenotypes are more damaged than low ones early in the flight period (April-May); symmetrical damage, probably acquired while resting, is commoner in females, while asymmetrical damage is more characteristic of males. Damage generally increases in both sexes through the flight period.
Comparison of the bulked Canary Island samples with museum material from North Africa and Iberia suggests that the former area is the more likely source of the island populations. However, samples from two islands more resemble Iberian stock and it is suggested that the butterfly may have colonized the islands, either by introduction or immigration, on two occasions.     

Spot distribution in the meadow brown butterfly, Maniola jurtina L. (Lepidoptera: Satyridae): South Welsh populations

Meadow brown butterflies, Maniola jurtina , were studied on Skokholm Island, off the Pembrokeshire coast, from 1976 to 1978 and at six other sites in south Wales from 1973 to 1977.
Daily survival of butterflies on Skokholm was estimated by capture-recapture data to be 0.70–0.84, but these values may be low because in the year of detailed study, 1976, dispersal rates between study sites were high and increased through the emergence period.
The butterflies were scored for the number and placing of the hind wing spots (Ford, 1975). Female populations in the east of our study area resembled English populations for they were unimodal at 0 spots. Spotting increased westwards until on Skokholm and the adjacent mainland the females caught were roughly equally likely to have 0, 1 or 2 spots. The Skokholm male populations had many 3-spotted individuals and so the mode of 2 in the spot-frequency distribution was less clear cut that in English populations. The trends in south Wales therefore resemble those found along the Cornish peninsula and on the Isles of Scilly. We suggest the increasingly maritime climate and the fragmentation of habitat on the coastal fringes of the species range are factors which may selectively favour butterflies with high flying and dispersal ability. Brakefield (1983) has offered evidence that more highly spotted meadow browns indeed have such an ability.     

Mitochondrial DNA variability in the Canary Islands honeybees (Apis mellifera L.)

The mitochondrial DNA (mtDNA) of individuals from 79 colonies of Apis mellifera from five Canary Islands was studied using the Dra I test based on the restriction of PCR products of the tRNAleu–COII intergenic region. Five haplotypes of the African (A) lineage and one of the west European (C) lineage were found. The haplotypes A14 and A15 are described for the first time. These haplotypes have a new P sequence named P₁. The wide distribution and high frequency of haplotype A15 suggest that it is characteristic of the Canarian Archipelago. Sources of haplotype variability of honeybee mtDNA in the Canary Islands (waves of colonization from Africa, queen importations, habitat diversification) are discussed.     

Spatial and temporal variation in distribution of Gelidium canariensis (Rhodophyta) from natural populations of the Canary Islands

This study was designed to investigate spatial and temporal variation in Gelidium canariensis populations at two shores in northern Gran Canaria during two years. Spatial scales ranged from some hundred meters (distance between shores), 10 to 30 m (distance between plots) to less than 3 m (distance between quadrats). Gelidium individuals were defined as distinct Gelidium clumps. The results show a significant difference in size of clumps between shores, but not on the smaller spatial scales. No significant temporal variation was found. There was no significant temporal or spatial variation in standing crop or density (counts made in quadrats where Gelidium was present, rather than counts for the total shore). Sporophytic and gametophytic clumps were also distinguished by identifying reproductive structures in the field. The total proportion of sporophytes was larger than the proportion of gametophytes, but at a smaller scale there could be a shift in dominance. The survival rate of clumps was similar between shores with a mean survival rate of 85%, but there was a significant difference in recruitment between shores. The results indicate a stable population structure. This revised version was published online in June 2006 with corrections to the Cover Date.     

Occurrence of the ocean triggerfish in the Eastern Atlantic (Canary Islands)

The occurrence, habitat and abundance are reported for the population of ocean triggerfish Canthidermis sufflamen (Balistidae) at El Hierro, Canary Islands. This is the first record from the Eastern Atlantic.     

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.     

Characterization of microsatellite loci in Brachyderes rugatus,the Canary Islands pine weevil (Coleoptera: Curculionidae)

The Canary Island pine weevil Brachyderes rugatus (Wollaston) consists of four allopatric subspecies that are thought to have arisen from several historic colonization events within the archipelago. We have isolated and optimized seven microsatellite loci from Brachyderes rugatus calvus from Gran Canaria. Six of these loci are polymorphic within B. rugatus (11–22 alleles per locus; heterozygosity between 0.43 and 0.84). There is no evidence for heterozygote deficit within populations or for linkage disequilibrium between pairs of loci. These molecular markers are likely to prove useful tools for quantifying the genetic variability of bottlenecked island populations.     

Macaronesian millipedes (Diplopoda) with emphasis on endemic species swarms on Madeira and the Canary Islands

Endemic species swarms constitute large fractions of the millipede faunas of Madeira (29 species of the Cylindroiulus madeirae group, plus six species of Acipes , out of a total of 60 species) and the Canary Islands (46 species of Dolichoiulus , plus four species of the Glomeris alluaudi-group , out of a total of about 79 species). The poorer faunas of the Azores (22 species) and the Cape Verde Islands (15 species) in contrast only include a few endemics. The Cylindroiulus madeirae group and Dolichoiulus show a high degree of diversity of structure (size, colour, leg length etc.) and habitat (laurisilva, xeric habitats, caves). The C. madeirae group, unlike Dolichoiulus , is strongly concentrated in the laurisilva. In this habitat, microhabitat differentiation is pronounced in both swarms.     

Mitochondrial DNA, ecology and morphology: interpreting the phylogeography of the Nesotes (Coleoptera: Tenebrionidae) of Gran Canaria (Canary Islands)

The genus Nesotes (Coleoptera: Tenebrionidae) is represented in the Canary Islands by 19 endemic species, the majority of which are single island endemics. Nesotes conformis and N. fusculus are described on four and three islands, respectively, but each forms a paraphyletic assemblage between Gran Canaria and the other islands. The other described species for Gran Canaria are N. quadratus, N. lindbergi and N. piliger. Thirty-six individuals representing the five species on Gran Canaria have been sequenced for 675 bp of the mitochondrial DNA (mtDNA) cytochrome oxidase II gene. Neighbour-joining analysis of maximum likelihood distances resulted in five distinct mtDNA lineages for N. quadratus, two of which also include mitotypes of N. conformis. Each of the other three species is found on only one mtDNA lineage. We propose from the molecular data that differentiation in a widespread N. quadratus-type ancestor was followed by morphological adaptation to coastal, pine and laurel forest habitats.     

Biodiversity of Apis mellifera populations from Tenerife (Canary Islands) and hybridisation with East European races

The biodiversity of honeybee (Apis mellifera) populations from Tenerife (Canary Islands, Spain) has been assessed by restriction analysis of a mitochondrial non-coding intergenic region. Seventy-nine colonies were analysed from thirteen apiaries in six populations that have been kept from recent queen introduction. The length and restriction pattern of the PCR amplified products of the intergenic region identified four mitochondrial haplotypes. One of these haplotypes shows the same restriction pattern and composition of the intergenic region carried by honeybees belonging to the African lineage. Two haplotypes are characterised by a particular intergenic region found with high frequency in the Canarian populations. The haplotype representative of the East European honeybee lineage shows a frequency of 35%, thus indicating introduction of queen honeybees. The finding of this haplotype in Canarian honeybees suggests that hybridisation between the endemic Apis mellifera populations and imported bees is occurring in Tenerife.     

Reconciling gene trees with organism history: the mtDNA phylogeography of three Nesotes species (Coleoptera: Tenebrionidae) on the western Canary Islands

The processes of island colonization and speciation are investigated through mtDNA studies on Canary Island beetles. The genus Nesotes (Coleoptera: Tenebrionidae) is represented by 19 endemic species on the Canary Islands, the majority of which are single island endemics. Nesotes conformis is the most widespread, occurring on Gran Canaria, Tenerife, La Palma and El Hierro. Nesotes conformis forms a paraphyletic assemblage, with a split between Gran Canaria and the other three islands. Nesotes conformis of the western Canary Islands cluster with Nesotes altivagans and Nesotes elliptipennis from Tenerife. Fifty‐two individuals from this western islands species complex have been sequenced for 675 base pairs of the mtDNA cytochrome oxidase II gene, representing Tenerife, La Palma and El Hierro. A neighbour joining analysis of maximum likelihood distances resulted in three distinct mtDNA lineages for N. conformis, two of which also include mitotypes of N. altivagans and N. elliptipennis. Through application of parametric bootstrap tests, we are able to reject hypotheses of monophyly for both N. conformis and N. altivagans. Nesotes altivagans and N. elliptipennis are poorly separated morphologically and mtDNA sequence data adds support to this being one species with a highly variable morphology. We propose that N. altivagans/N. elliptipennis is recently derived from two ancestral mtDNA lineages within N. conformis from the Teno region of Tenerife. We further propose colonization of the younger islands of La Palma and El Hierro by N. conformis from a mitochondrial lineage within the Teno massif (colonization; diversification; mitochondrial DNA; Canary Islands; Coleoptera).     

Study of dentition in lizards from Gran Ganaria Island (Canary Islands) and its ecological and evolutionary significance

The dentition of Gallotia stehlini from one extant and two subfossil populations dated as 4000 and 2000 years before present was studied. Body measurements were similar in the two subfossil populations, but much greater than the largest sizes observed today in G. stehlini. The morphology of the dental cusps in this G. stehlini differs greatly from that of other Lacertidae, including other congeneric Canarian species; this has been connected with a vegetarian diet. A decrease in heterodonty with size of the animal is also seen which contrasts strongly with the models observed in the Mediterranean lacertid lizards.     

Evolution and biogeography of the genus Tarentola (Sauria: Gekkonidae) in the Canary Islands,inferred from mitochondrial DNA sequences

Sequences from fragments of the 12S ribosomal RNA and cytochrome b mitochondrial genes were used to analyze phylogenetic relationships among geckos of genus Tarentola from the Canary Islands. A surprisingly high level of within island differentiation was found in T. delalandii in Tenerife and T. boettgeri in Gran Canaria. Molecular differentiation between populations of T. angustimentalis on Lanzarote and Fuerteventura, and between Moroccan and Iberian Peninsula T. mauritanica, also indicate that at least two subspecies should be recognized within each of them. Phylogenetic relationships among these species reveals a higher level of differentiation and a more complex colonization pattern than those found for the endemic genus Gallotia. Lack of evidence for the presence of T. boettgeri bischoffi on the island of Madeira does not seem to support the origin of T. delalandii, T. gomerensis and the canarian subspecies of T. boettgeri from this island, whereas molecular data confirms that T. angustimentalis is a sister species of the continental T. mauritanica. Several independent colonization events from the continent and the extinction of some species are probably responsible for the current distribution of Tarentola in the Canary Islands.     

The evolutionary significance of bimodal emergence in the butterfly, Maniola jurtina (Lepidoptera: Satyrinae) (L.).

Most temperate butterflies exhibit a tightly synchronized unimodal adult emergence to facilitate mate location. Exceptions are presumably subject to unusual selection pressure. This study examines the pattern of emergence in Maniola jurtina , which was found to exhibit both unimodal and bimodal emergence patterns at different sites in south-east England. The bimodal pattern was found on chalk grassland; elsewhere the emergence was unimodal. Adults from each emergence peak rarely meet, suggesting that there may be some degree of reproductive isolation. Morphological measurements and electrophoretic analysis of allozyme frequencies are carried out to quantify differentiation between emergence peaks. Captive stock was reared to examine differences in the immature stages. Butterflies from each emergence differ significantly in most morphological variables measured, those from the second peak tending to be smaller. The immature stages differ in morphology and longevity of the egg stage. Allozyme frequencies did not differ between peaks, suggesting that they are not reproductively isolated. Explanations for the maintenance of differences between emergence peaks despite gene flow are discussed. I propose that division of offspring between two emergence times may have evolved to avoid the risk inherent in placing all offspring in one peak which may be rendered inviable by temporal fluctuations in habitat quality.     

Population genetics of Matthiola bolleana (Brassicaceae) in the Canary Islands

Genetic variation at 11 isozyme loci was used to explore the levels and apportionment of genetic variation in the eight known populations of Matthiola bolleana, an endemic Brassicaceae to the Eastern Canarian islands of Fuerteventura and Lanzarote. Within islands, ecosystem antiquity and uniformity, lack of evidence for selection or genetic bottlenecks, the high genetic identities between the populations, and the low values of F _ST converge to suggest that the high levels of variation detected have been maintained in a context of prolonged environmental stability through an overall predominance of outbreeding and unrestricted gene flow. Despite the geographical closeness between Fuerteventura and Lanzarote and the long range dispersal features of the propagules of M. bolleana, we detected a striking qualitative genetic differentiation between the two islands. We suggest that wind direction has made seed and pollen flow between Fuerteventura and Lanzarote much less likely than expected, and that the lack of inter-island dispersal has far overriden the influence of stochastic forces and of the reproductive attributes of M. bolleana in shaping the patterns of inter-island genetic differentiation. However, genetic similarity in M. bolleana is within the ranges defined by Canarian taxa for which the extent of genetic differentiation has also been assessed using the values of isozyme genetic identity.     

Predicting the potential habitat of the harmful cyanobacteria Lyngbya majuscula in the Canary Islands (Spain)

This study presents the ecological niche and the potential distribution of Lyngbya majuscula in the Canary Islands (Spain) based on a bloom of this species on the eastern side of the Canarian Archipelago, in the Marine Reserve of La Graciosa (MRG). This finding represents the first L. majuscula bloom recorded in waters around the Canary Islands and this side of the Atlantic Ocean. The modeled suitability map revealed a potential distribution of L. majuscula in rocky and sandy habitats within shallow and sheltered areas exposed to sedimentation; where L. majuscula blooms had not previously been reported. The L. majuscula bloom detected in MRG is affecting rocky and sandy communities in this area. The possible expansion of these blooms may have harmful effects on important communities in the Canary Islands, including some of high ecological importance such as the Cymodocea nodosa meadows. Results of the L. majuscula distribution model presented here can be used to develop management strategies that avoid or minimize the risk of future bloom occurrences or expansions and their negative effects on the environment. The causes of L. majuscula blooms in MRG are being investigated.     

On the identity of Riccia teneriffae S.W.Arnell (Marchantiophyta: Ricciaceae) and a note on R. cavernosa Hoffm. in the Canary Islands

Abstract

We revised both the holotype and an isotype of Riccia teneriffae S.W.Arnell 1962 and additionally revised our own collections of Riccia cavernosa Hoffm. 1795 from the Canary Islands. Since the types of R. teneriffae represent R. cavernosa, and the latter name precedes the former, R. teneriffae should be treated as a synonym of R. cavernosa. In the Canary Islands, R. cavernosa appears to be rare. It has been found on La Gomera, Gran Canaria, Lanzarote, and Tenerife. We report it as new to Fuerteventura. R. cavernosa inhabits ephemeral, thin layers of mud. Very rarely it occurs on basaltic pyroclasts. SEM images of spores are presented. The local distribution is mapped.