Plant species richness in the Cape Verde Islands—eco-geographical determinants

Plant species richness in the Cape Verde archipelago is examined relative to island eco-geographical factors. Species-area and species-area-habitat relationships are analysed using the classical species-area model and the recently proposed species-choros model. The number of floristic zones (used to estimate the choros parameter) provides an adequate estimate of the potential habitat diversity, and the species-choros model achieved a better fit with both total flora and endemic species. In addition to area and habitat diversity, longitude also emerges as an important determinant of species diversity, whereas latitude, minimum distance to the nearest island, and total rural population do not display any correlation. As in other insular ecosystems, the species richness (about 140 per 100 km²) is lower than in nearby mainland regions; the proximity to the desert areas of the Sahel can also be seen as related with this low value. The floristic heterogeneity in Cape Verde is high, as is usual in island ecosystems. In a comparative analysis of the species richness on the different islands (using α-values), Brava stands out as having the highest total flora species densities, while for endemic flora Brava and São Nicolau jointly occupy the leading position. The high diversity for both total and endemic species on Santo Antão, São Vicente, São Nicolau, Fogo and Brava reinforces their importance in conservation terms - in the case of most of them, something that is already recognized in the established network of protected areas.     

Integrated species delimitation and conservation implications of an endangered weevil Pachyrhynchus sonani (Coleoptera: Curculionidae) in Green and Orchid Islands of Taiwan

Oceanic islands are productive habitats for generating new species and high endemism, which is primarily due to their geographical isolation, smaller population sizes and local adaptation. However, the short divergence times and subtle morphological or ecological divergence of insular organisms may obscure species identity, so the cryptic endemism on islands may be underestimated. The endangered weevil Pachyrhynchus sonani Kôno (Coleoptera: Curculionidae: Entiminae: Pachyrhynchini) is endemic to Green Island and Orchid Island of the Taiwan‐Luzon Archipelago and displays widespread variation in coloration and host range, thus raising questions regarding its species boundaries and degree of cryptic diversity. We tested the species boundaries of P. sonani using an integrated approach that combined morphological (body size and shape, genital shape, coloration and cuticular scale), genetic (four genes and restriction site‐associated DNA sequencing, RAD‐seq) and ecological (host range and distribution) diversity. The results indicated that all the morphological datasets for male P. sonani, except for the colour spectrum, reveal overlapping but statistically significant differences between islands. In contrast, the morphology of the female P. sonani showed minimum divergence between island populations. The populations of P. sonani on the two islands were significantly different in their host ranges, and the genetic clustering and phylogenies of P. sonani established two valid evolutionary species. Integrated species delimitation combining morphological, molecular and ecological characters supported two distinct species of P. sonani from Green Island and Orchid Island. The Green Island population was described as P. jitanasaius sp.n. Chen & Lin, and it is recommended that its threatened conservation status be recognized. Our findings suggest that the inter‐island speciation of endemic organisms inhabiting both islands may be more common than previously thought, and they highlight the possibility that the cryptic diversity of small oceanic islands may still be largely underestimated.     

Systematics,biogeography and evolution of the endemic Hemidactylus geckos (Reptilia,Squamata, Gekkonidae) of the Cape Verde Islands: based on morphology and mitochondrial and nuclear DNA sequences

A total of 1854 bp of mitochondrial DNA (669 bp of cytochrome b (cyt b) and 386 bp of 12S rRNA), and 804 bp of a nuclear gene (RAG2) were investigated in endemic Hemidactylus from eight Cape Verde Islands, and used to explore their phylogeny, biogeography and evolution. Maximum‐likelihood, maximum‐parsimony and Bayesian analyses based on mtDNA revealed four well‐supported clades with uncorrected genetic divergences of 7.8–12.4% in the cyt b plus 12S rRNA genes, which were also supported by nuclear DNA. A population from the southern island of Fogo is the most divergent in both molecules and morphology and is described as Hemidactylus lopezjuradoi sp. n., and the populations on Sal and Boavista are also assigned species status as H. boavistensis. Although divergent in their DNA, the clade on S. Nicolau and that in the north‐western islands are morphologically similar and both are assigned to H. bouvieri for the present. Hemidactylus b. razoensis from Raso is genetically similar to H. b. bouvieri and differs only in its smaller body size. A molecular clock suggests that the ancestor of the endemic Hemidactylus of the Cape Verde Islands colonized the archipelago approximately 10 ± 2.48 Mya, perhaps reaching the north‐eastern islands first. The H. lopezjuradoi lineage separated soon after, and the north‐western islands were colonized progressively but slowly, S. Nicolau probably being reached first, then S. Vicente and islands on the same bank, and finally Sto. Antão, which is likely to have been colonized less than 1 Mya. Hemidactylus boavistensis is abundant on the arid islands where it occurs, but H. bouvieri appears to have been uncommon at least since it was described 130 years ago, and the same may be true of H. lopezjuradoi sp. n. The impact of introduced H. angulatus and H. mabouia on the endemic Hemidactylus of the Cape Verde Islands is not clear, but the discovery of substantial genetic diversity in endemic Cape Verde Hemidactylus means that the conservation requirements of the group should be reassessed.     

Trans-oceanic host dispersal explains high seabird tick diversity on Cape Verde islands

Parasites represent ideal models for unravelling biogeographic patterns and mechanisms of diversification on islands. Both host-mediated dispersal and within-island adaptation can shape parasite island assemblages. In this study, we examined patterns of genetic diversity and structure of Ornithodoros seabird ticks within the Cape Verde Archipelago in relation to their global phylogeography. Contrary to expectations, ticks from multiple, geographically distant clades mixed within the archipelago. Trans-oceanic colonization via host movements probably explains high local tick diversity, contrasting with previous research that suggests little large-scale dispersal in these birds. Although host specificity was not obvious at a global scale, host-associated genetic structure was found within Cape Verde colonies, indicating that post-colonization adaptation to specific hosts probably occurs. These results highlight the role of host metapopulation dynamics in the evolutionary ecology and epidemiology of avian parasites and pathogens.     

Weight–length and length–length relationships for reef fish species from the Cape Verde Archipelago (tropical north‐eastern Atlantic)

This study reports weight–length and length–length relationships for selected coastal reef fish species of the Cape Verde Archipelago (tropical north‐eastern Atlantic). Specimens were caught with different types of gear (long‐lines, hand‐lines, purse‐seines and traps) during commercial fishing activities and sampled during fish market operations. A total of 8328 individuals were sampled, representing 29 species from 14 Families. This study provides the first references on weight–length and length–length relationships for five and 23 fish species worldwide, for 10 and 24 species for the Eastern Atlantic and for 12 and 26 species for Cape Verde Archipelago, respectively. Additionally, it provides revised weight–length relationships for 11 species from Cape Verde waters.     

The separation of Pterodroma madeira (Zino's Petrel) from Pterodroma feae (Fea's Petrel) (Aves: Procellariidae)

The taxonomic status of petrels from the North East Atlantic has long been a matter of debate. Breeding colonies of petrels occurring on the islands of Madeira, Bugio and Cape Verde were originally thought to be outlying populations of the polytypic species Pterodroma mollis . Subsequent taxonomic treatments have varied considerably in their classification of birds from these islands. The petrel populations on Madeira and Bugio represent some of Europe's rarest breeding birds and their exact species designation, and hence relation to conservation mandates, is a question of considerable importance. In this study we use molecular techniques alongside more traditional taxonomic characters to confirm the existence of two species of the genus Pterodroma in the Archipelago of Madeira. We also discuss identification of these species in the field and the implications for their conservation management.     

Characterizing morphological (co)variation using structural equation models: Body size,allometric relationships and evolvability in a house sparrow metapopulation

Body size plays a key role in the ecology and evolution of all organisms. Therefore, quantifying the sources of morphological (co)variation, dependent and independent of body size, is of key importance when trying to understand and predict responses to selection. We combine structural equation modeling with quantitative genetics analyses to study morphological (co)variation in a meta‐population of house sparrows (Passer domesticus). As expected, we found evidence of a latent variable “body size,” causing genetic and environmental covariation between morphological traits. Estimates of conditional evolvability show that allometric relationships constrain the independent evolution of house sparrow morphology. We also found spatial differences in general body size and its allometric relationships. On islands where birds are more dispersive and mobile, individuals were smaller and had proportionally longer wings for their body size. Although on islands where sparrows are more sedentary and nest in dense colonies, individuals were larger and had proportionally longer tarsi for their body size. We corroborated these results using simulations and show that our analyses produce unbiased allometric slope estimates. This study highlights that in the short term allometric relationships may constrain phenotypic evolution, but that in the long term selection pressures can also shape allometric relationships.     

Parallel gigantism and complex colonization patterns in the Cape Verde scincid lizards Mabuya and Macroscincus (Reptilia: Scincidae) revealed by mitochondrial DNA sequences

The scincid lizards of the Cape Verde islands comprise the extinct endemic giant Macroscincus coctei and at least five species of Mabuya, one of which, Mabuya vaillanti, also had populations with large body size. Phylogenetic analysis based on DNA sequences derived from the mitochondrial cytochrome b, cytochrome oxidase I and 12S rRNA genes (711, 498 and 378 base pairs (bp), respectively) corroborates morphological evidence that these species constitute a clade and that Macroscincus is unrelated to very large skinks in other areas. The relationships are ((M. vaillanti and Mabuya delalandii) (Mabuya spinalis and Macroscincus coctei (Mabuya fogoensis nicolauensis (Mabuya fogoensis antaoensis and Mabuya stangeri)))). The Cape Verde archipelago was colonized from West Africa, probably in the Late Miocene or Early Pliocene period. The north-eastern islands were probably occupied first, after which the ancestor of M. vaillanti and M. delalandii may have originated on Boavista, the ancestor of the latter species arriving on Santiago or Fogo later. The M. fogoensis--M. stangeri clade colonized the islands of Branco, Razo, Santa Luzia and São Vicente from São Nicolau and reached Santo Antão after this. Colonization of these northeastern islands was slow, perhaps because the recipient islands had not developed earlier or because colonization cut across the path of the Canary Current and the Northeast Trade Winds, the main dispersing agents in the region. Rapid extension of range into the southwestern islands occurred later in M. spinalis and then in M. vaillanti and M. delalandii. The long apparent delay between the origin of these species and their southwestern dispersal may have been because there were earlier colonizations of the southern islands which excluded later ones until the earlier inhabitants were exterminated by volcanic or climatic events. The evolution of large size in Macroscincus occurred in the northwestern islands and was paralleled in the eastern and southern islands by populations of M. vaillanti. Both cases of size increase in Cape Verde skinks were accompanied by the development of herbivory.     

Re: Phylogenetic relationships in Sphingidae (Insecta: Lepidoptera): initial evidence from two nuclear genes

Partial DNA sequences from two mitochondrial (mt) and one nuclear gene (cytochrome b, 12S rRNA, and C-mos) were used to estimate the phylogenetic relationships among the six extant species of skinks endemic to the Cape Verde Archipelago. The species form a monophyletic unit, indicating a single colonization of the islands, probably from West Africa. Mabuya vaillanti and M. delalandii are sister taxa, as indicated by morphological characters. Mabuya fogoensis and M. stangeri are closely related, but the former is probably paraphyletic. Mabuya spinalis and M. salensis are also probably paraphyletic. Within species, samples from separate islands always form monophyletic groups. Some colonization events can be hypothesized, which are in line with the age of the islands. C-mos variation is concordant with the topology derived from mtDNA.     

Trophic habits of feral cats in the high mountain shrublands of the Macaronesian islands (NW Africa,Atlantic Ocean)

Feral cats Felis catus Linnaeus, 1758 have contributed to the extinction of numerous native species on islands, which are clearly sources of global biodiversity. We studied the diet of this introduced predator in the Madeira and Cape Verde archipelagos, which harbour important colonies of endangered seabirds in the high mountain habitats, and compared the results with those obtained in the same habitat in the Canary Islands, Macaronesian archipelago. On Madeira, 461 prey were identified from 143 scat groups. Mammals, overall mice, constituted the basic diet appearing in 95% of cat scats. On Fogo (Cape Verde), 657 prey items were obtained from 145 scats, and mammals were also the most important prey, reaching a frequency of occurrence of 88%. Although introduced mammals were the main prey category on all Macaronesian islands, we observed variation in feral cat diet among these islands. Birds were more frequently consumed on Madeira, lizards on Tenerife (Canaries) and invertebrates on Fogo. No specific differences were observed in relation to La Palma. We suggest that the diet composition on these islands varies according to the respective availability of the different prey types.     

Insight into an island radiation: the Tarentola geckos of the Cape Verde archipelago

Aim To reassess the relationships between Tarentola geckos from the Cape Verde Islands by including specimens from all islands in the range. To determine the variation within forms by sequencing over 400 specimens, thereby allowing the discovery of cryptic forms and resolving some of the issues raised previously. This extensive sampling was also used to shed light on distributions and to explain genetic diversity by comparing the ages and ecological and geological features of the islands (size, elevation and habitat diversity). Location The Cape Verde Islands: an oceanic archipelago belonging to the Macaronesian biogeographic region, located around 500 km off Senegal. Methods A total of 405 new specimens of Tarentola geckos were collected from nine islands with very different geological histories, topography, climate and habitats. Mitochondrial cytochrome b (cyt b) gene and 12S rRNA partial sequences were obtained and analysed using phylogenetic methods and networks to determine molecular diversity, demographic features and phylogeographic patterns. Results The phylogenetic relationships between all known forms of Cape Verdean Tarentola specimens were estimated for the first time, the relationships between new forms were assessed and previously hypothesized relationships were re‐examined. Despite the large sample size, low intraspecific diversity was found using a 303‐bp cyt b fragment. Star‐like haplotype networks and statistical tests suggest the past occurrence of a rapid demographic and geographical expansion over most of the islands. Genetic variability is positively correlated with size, elevation and habitat diversity of the islands, but is not linearly related to the age of the islands. Biogeographical patterns have, in general, high concordance with phylogenetic breaks and with the three eco‐geographical island groups. Volcanism and habitat diversity, both tightly linked with island ontogeny, as postulated by the general dynamic model of oceanic island biogeography, as well as present and historical size of the islands appear to be the main factors explaining the genetic diversity of this group. Main conclusions The Tarentola radiation was clarified and is clearly associated with the geological and ecological features of the islands. Two factors may account for the low intraspecific variation: (1) recent volcanic activity and high ecological stress, and (2) poor habitat diversity within some islands. More studies are needed to align taxonomy with phylogenetic relationships, whereas GIS modelling may help to predict precise species distributions.     

Mismatch between shape changes and ecological shifts during the post-settlement growth of the surgeonfish, Acanthurus triostegus

Background

Many coral reef fishes undergo habitat and diet shifts during ontogeny. However, studies focusing on the physiological and morphological adaptations that may prepare them for these transitions are relatively scarce. Here, we explored the body shape variation related to ontogenetic shifts in the ecology of the surgeonfish Acanthurus triostegus (Acanthuridae) from new settler to adult stages at Moorea Island (French Polynesia). Specifically, we tested the relationship between diet and habitat shifts and changes in overall body shape during the ontogeny of A. triostegus using a combination of geometric morphometric methods, stomach contents and stable isotope analysis.

Results

After reef settlement, stable isotope composition of carbon and nitrogen revealed a change from a zooplanktivorous to a benthic algae diet. The large amount of algae (> 75% of stomach contents) found in the digestive tract of small juveniles (25?C30 mm SL) suggested the diet shift is rapid. The post-settlement growth of A. triostegus is highly allometric. The allometric shape changes mainly concern cephalic and pectoral regions. The head becomes shorter and more ventrally oriented during growth. Morphological changes are directly related to the diet shift given that a small mouth ventrally oriented is particularly suited for grazing activities at the adult stage. The pectoral fin is more anteriorely and vertically positioned and its basis is larger in adults than in juveniles. This shape variation had implications for swimming performance, manoeuvrability, turning ability and is related to habitat shift. Acanthurus triostegus achieves its main transformation of body shape to an adult-like form at size of 35?C40 mm SL.

Conclusion

Most of the shape changes occurred after the reef colonization but before the transition between juvenile habitat (fringing reef) and adult habitat (barrier reef). A large amount of allometric variation was observed after diet shift from zooplankton to benthic algae. Diet shift could act as an environmental factor favouring or inducing morphological changes. On the other hand, the main shape changes have to be achieved before the recruitment to adult populations and start negotiating the biophysical challenges of locomotion and feeding in wave- and current-swept outer reef habitat.     

Postmetamorphic ontogenetic allometry and the evolution of skull shape in Nest‐building frogs Leptodactylus (Anura: Leptodactylidae)

Allometry constitutes an important source of morphological variation. However, its influence in head development in anurans has been poorly explored. By using geometric morphometrics followed by statistical and comparative methods we analyzed patterns of allometric change during cranial postmetamorphic ontogeny in species of Nest‐building frogs Leptodactylus (Leptodactylidae). We found that the anuran skull is not a static structure, and allometry plays an important role in defining its shape in this group. Similar to other groups with biphasic life‐cycle, and following a general trend in vertebrates, ontogenetic changes mostly involve rearrangement in rostral, otoccipital, and suspensorium regions. Ontogenetic transformations are paralleled by shape changes associated with evolutionary change in size, such that the skulls of species of different intrageneric groups are scaled to each other, and small and large species show patterns of paedomorphic/peramorphic features, respectively. Allometric trajectories producing those phenotypes are highly evolvable though, with shape change direction and magnitude varying widely among clades, and irrespective of changes in absolute body size. These results reinforce the importance of large‐scale comparisons of growth patterns to understand the plasticity, evolution, and polarity of morphological changes in different clades.     

PHYLOGEOGRAPHIC STUDIES IN THE TROPICAL SEAWEED CLADOPHOROPSIS MEMBRANACEA (CHLOROPHYTA,ULVOPHYCEAE) REVEAL A CRYPTIC SPECIES COMPLEX1

The seaweed Cladophoropsis membranacea (Hofman Bang ex. C. Agardh) Børgesen is a widely distributed species on coral reefs and along rocky coastlines throughout the tropics and subtropics. In a recent population‐level survey openface>1600 individuals with eight microsatellite loci, a number of isolates from biogeographically disjunct locations could not be amplified for any of the loci. Nonamplifiable and amplifiable isolates co‐occurred within the Canary Islands, Cape Verde Islands, and in the Caribbean. These unexpected results led to question whether or not C. membranacea is a single species. Phylogenetic relationships were evaluated using rDNA ITS1 and ITS2 sequence comparisons from 42 isolates sampled from a subset of 30 of the 66 locations. Four well‐supported clades were identified. Sequence divergence within clades was <1%, whereas between‐clade divergence was 2%–3%. Intraindividual variation was extremely low with no effects on the analysis. A strong, but imperfect, correspondence was found between ITS clades and amplifiable microsatellite loci. It is concluded that C. membranacea consists of three cryptic species. Using Pacific isolates as an outgroup, the most basal clade included the Central Canary Islands, Cape Verde, and Bonaire (Caribbean) isolates and thus spanned the widest latitude. Two derived sister clades consisted of a southern transtropical group stretching across the SE Caribbean to the Cape Verde Islands and African coast (but not the Canary Islands) and a NE‐Canary Island‐Mediterranean clade that also included the Red Sea. The detection of overlapping biogeographic distributions highlights the importance of ecotypic differentiation with respect to temperature and the importance of shifting sea surface isotherms that have driven periodic extinctions and recolonizations of the Canary Islands—a crossroads of marine floral exchange—since the last glacial maximum.     

Long-distance colonization and radiation in gekkonid lizards, Tarentola (Reptilia: Gekkonidae), revealed by mitochondrial DNA sequences

Morphological systematics makes it clear that many non-volant animal groups have undergone extensive transmarine dispersal with subsequent radiation in new, often island, areas. However, details of such events are often lacking. Here we use partial DNA sequences derived from the mitochondrial cytochrome b and 12S rRNA genes (up to 684 and 320 bp, respectively) to trace migration and speciation in Tarentola geckos, a primarily North African clade which has invaded many of the warmer islands in the North Atlantic Ocean. There were four main invasions of archipelagos presumably by rafting. (i) The subgenus Neotarentola reached Cuba up to 23 million years (Myr) ago, apparently via the North Equatorial current, a journey of at least 6000 km. (ii) The subgenus Tarentola invaded the eastern Canary Islands relatively recently covering a minimum of 120 km. (iii) The subgenus Makariogecko got to Gran Canaria and the western Canary Islands 7-17.5 Myr ago, either directly from the mainland or via the Selvages or the archipelago of Madeira, an excursion of 200-1200 km. (iv) A single species of Makariogecko from Gomera or Tenerife in the western Canaries made the 1400 km journey to the Cape Verde Islands tip to 7 Myr ago by way of the south-running Canary current. Many journeys have also occurred within archipelagos, a minimum of five taking place in the Canaries and perhaps 16 in the Cape Verde Islands. Occupation of the Cape Verde archipelago first involved an island in the northern group, perhaps São Nicolau, with subsequent spread to its close neighbours. The eastern and southern islands were colonized from these northern islands, at least two invasions widely separated in time being involved. While there are just three allopatric species of Makariogecko in the Canaries, the single invader of the Cape Verde Islands radiated into five, most of the islands being inhabited by two of these which differ in size. While size difference may possibly be a product of character displacement in the northern islands, taxa of different sizes reached the southern islands independently.     

The importance of historical ecology for interpreting evolutionary processes in plants of oceanic islands

Oceanic islands and archipelagos are natural laboratories for investigating patterns and processes of evolution. Islands change with the course of time, resulting in a dynamic ontogeny over millions of years. The combined forces of tectonic plate subsidence and erosion from waves, wind, and rainwater bring about substantial geomorphological change over millions of years, until islands eventually disappear under the sea. Added to these long‐term natural changes to the environment of the islands are the changes caused by human activities in recent centuries. After humans reach a previously unpopulated island, they utilize the natural resources for their own survival, cutting forests for making houses, boats, and firewood. The size of the human population and the length of time on the island determine the degree of environmental impact. Evolutionary processes in plants of oceanic islands take place during ontogeny of the islands, resulting in population divergence, speciation, and hybridization. Due to the dramatic alterations suffered by many islands over millions of years, the present patterns of distribution and ecology of species within endemic groups may have little to do with the patterns when the species originated. Understanding these environmental changes is fundamental to infer a founder effect, reasons for levels of genetic variation within and among populations, and modes of speciation. Special caution must be exercised while making comparisons between groups located on islands of different geological ages and that have endured differing environmental modifications from humans. Examples are provided from the Juan Fernández Archipelago and Lord Howe Island.     

A comparative study on genetic effects of artificial and natural habitat fragmentation on Loropetalum chinense (Hamamelidaceae) in Southeast China

Elucidating the demographic and landscape features that determine the genetic effects of habitat fragmentation has become fundamental to research in conservation and evolutionary biology. Land-bridge islands provide ideal study areas for investigating the genetic effects of habitat fragmentation at different temporal and spatial scales. In this context, we compared patterns of nuclear microsatellite variation between insular populations of a shrub of evergreen broad-leaved forest, Loropetalum chinense, from the artificially created Thousand-Island Lake (TIL) and the Holocene-dated Zhoushan Archipelago of Southeast China. Populations from the TIL region harboured higher levels of genetic diversity than those from the Zhoushan Archipelago, but these differences were not significant. There was no correlation between genetic diversity and most island features, excepting a negative effect of mainland–island distance on allelic richness and expected heterozygosity in the Zhoushan Archipelago. In general, levels of gene flow among island populations were moderate to high, and tests of alternative models of population history strongly favoured a gene flow-drift model over a pure drift model in each region. In sum, our results showed no obvious genetic effects of habitat fragmentation due to recent (artificial) or past (natural) island formation. Rather, they highlight the importance of gene flow (most likely via seed) in maintaining genetic variation and preventing inter-population differentiation in the face of habitat ‘insularization'' at different temporal and spatial scales.     

Ant communities on small tropical islands: effects of island size and isolation are obscured by habitat disturbance and ‘tramp’ ant species

Aim Comparisons among islands offer an opportunity to study the effects of biotic and abiotic factors on small, replicated biological communities. Smaller population sizes on islands accelerate some ecological processes, which may decrease the time needed for perturbations to affect community composition. We surveyed ants on 18 small tropical islands to determine the effects of island size, isolation from the mainland, and habitat disturbance on ant community composition. Location Thousand Islands Archipelago (Indonesian name: Kepulauan Seribu) off Jakarta, West Java, Indonesia. Methods Ants were sampled from the soil surface, leaf litter and vegetation in all habitat types on each island. Island size, isolation from the mainland, and land‐use patterns were quantified using GIS software. The presence of settlements and of boat docks were used as indicators of anthropogenic disturbance. The richness of ant communities and non‐tramp ant species on each island were analysed in relation to the islands’ physical characteristics and indicators of human disturbance. Results Forty‐eight ant species from 5 subfamilies and 28 genera were recorded from the archipelago, and approximately 20% of the ant species were well‐known human‐commensal ‘tramp’ species. Islands with boat docks or human settlements had significantly more tramp species than did islands lacking these indicators of anthropogenic disturbance, and the diversity of non‐tramp species decreased with habitat disturbance. Main conclusions Human disturbance on islands in the Thousand Islands Archipelago promotes the introduction and/or establishment of tramp species. Tramp species affect the composition of insular ant communities, and expected biogeographical patterns of ant richness are masked. The island with the greatest estimated species richness and the greatest number of unique ant species, Rambut Island, is a forested bird sanctuary, highlighting the importance of protected areas in preserving the diversity of species‐rich invertebrate faunas.     

Zur Situation der MilaneMilvus milvus fasciicauda (Hartert, 1914) undMilvus m. migrans (Boddaert, 1783) auf den Kapverdischen Inseln

Zusammenfassung WährendMilvus milvus fasciicauda undMilvus m. migrans in den 1950er Jahren noch sympatrisch auf fast allen Inseln anzutreffen waren, umfaßt der Bestand heute, nach der Erfassung in den Jahren 1996 und 1997, lediglich zehn Individuen pro Art auf je einer Insel. Diese drastische Abnahme ist unter anderem auf Landschaftsveränderungen, Vergiftungen und Verfolgung durch den Menschen zurückzuführen.

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Status of the KitesMilvus milvus fasciicauda (Hartert, 1914) andMilvus m. migrans (Boddaert, 1783) on the Cape Verde Islands

Summary In 1996 and 1997 population size ofMilvus milvus fasciicauda andMilvus m. migrans was censused and estimated to be five to six individuals for the former and three to five for the latter. In the 1950's,Milvus m. migrans and the endemicMilvus milvus fasciicauda were sympatric taxa on most of the Cape Verde Islands. While still widely distributed in the 1980's, the Black Kite today is restricted to Boavista, the eastermost island. The Red Kite less widely distributed in the 1950's and in the 1980's restricted to three islands, is now found only on Santo Antao, the westernmost island. There is no evidence of breeding of either of the two Kites.This drastic reduction of Kites on the Cape Verde Islands may be due to habitat changes associated with the expansion of the Sahel region resulting in an increase in aridity on the islands, the pressure from human activities in the form of new settlements, structural changes in agriculture like overgrazing by goats, as well as the use of poisened meat as a bait, the use of rodentizides, and persecution.