Stomach contents of mass-stranded short-finned pilot whales (Globicephala macrorhynchus) from North Carolina

We examined the stomach contents of 27 short‐finned pilot whales (Globicephala macrorhynchus) that mass stranded on the North Carolina coast on 15 January 2005. Eleven whales had prey parts in their forestomachs. We used frequency of occurrence and numerical abundance to assess the relative importance of prey. Brachioteuthis riisei (numerical abundance 28%), an oceanic species, was the most important cephalopod prey, but Taonius pavo (12%) and Histioteuthis reversa (9%) also represented a substantial part of the diet. A large number of otoliths belonging to the fish Scopelogadus beanii were present (25%). These results differ from reports of the stomach contents of short‐finned pilot whales from the Pacific coast in which neritic species dominate the diet. Our findings also suggest that there is a considerable difference between the diet of short‐ and long‐finned pilot whales (Globicephala melas) in the western North Atlantic. The latter feed predominantly on the long‐finned squid (Loligo pealei) whereas the former feed on deep‐water species. Our results indicate the whales fed primarily off the continental shelf prior to stranding.     

Activity budget and diving behavior of gray whales (Eschrichtius robustus) in feeding grounds off coastal British Columbia

Behavior and diving patterns of summer resident gray whales ( Eschrichtius robustus ) foraging on mysids were studied in coastal bays along the north shore of Queen Charlotte Strait, British Columbia. In this region, gray whales were found to feed primarily on planktonic prey rather than on the benthos as in their primary feeding areas further north. During the summers of 1999 and 2000, whales spent most of their time actively feeding or searching for prey (77%), whereas only 15% of their time was spent traveling and 8% socializing. The majority of the dives were short; the mean dive duration was 2.24 min with approximately three respirations per surfacing and 15 s between blows. Whales dove frequently (26.7 h⁻¹), spending only 17% of their time at the surface with an overall blow rate of 1.14 respirations per minute. Activity states were characterized by significantly different diving and respiratory parameters; feeding whales dove more frequently, with shorter intervals between respirations, thus spending less time at the surface compared to when traveling or searching. This diving pattern differs from benthic-feeding whales and likely optimizes capture of the mobile mysid swarms in shallow waters.     

The long-term ecology of the lost forests of La Laguna, Tenerife (Canary Islands)

Aim We report the first analysis of the long‐term ecology of Tenerife, in order to establish a pre‐colonization base‐line and to assess the effect of human activity and the role of climatic variation on vegetation during the Late Holocene. Location A former lake bed in the city of La Laguna (Tenerife, Canary Islands, Spain). Methods A sedimentary sequence of over 2 m was obtained from the former lake bed. Fossil pollen and microfossil charcoal concentrations were analysed. Radiocarbon dating of the sequence indicates that it spans approximately the last 4700 years. The pollen diagram was zoned using optimal splitting within psimpoll 4.25. Results Three pollen zones were differentiated: (1) in Zone L1 (c. 4700–2900 cal. yr bp ) a mixed forest was dominated by Quercus, Carpinus, Myrica and Pinus; (2) in Zone L2 (c. 2900–2000 cal. yr bp ) the laurel forest taxa increased, while Pinus, Juniperus and Phoenix declined; and (3) Zone L3 (c. 2000–400 cal. yr bp ) was characterized by the decline of Carpinus and Quercus and the abundance of laurel forest taxa (e.g. Myrica). Neither Carpinus nor Quercus was hitherto considered to be native to the Canary Islands. Their decline started c. 2000 years ago, coinciding with microfossil charcoal evidence of increased burning and with archaeological evidence for the first human settlement on Tenerife. Main conclusions Between c. 4700 and 2000 cal. yr bp , the composition of the forest in the valley of La Laguna was very different from what it is at present. In particular, Quercus and Carpinus appear to have been significant components, alongside components of the present‐day laurel forest, and the native pine (Pinus canariensis) forest and thermophilous woodland were also more prevalent in the region (but probably not within the lake basin itself) until 3000 cal. yr bp . The subsequent decline of Quercus and Carpinus led to the establishment of the present laurel forest in the region and a shift to more open vegetation types. These changes indicate that the aboriginal inhabitants of the islands, the Guanches, had a far more profound impact on the vegetation of Tenerife than hitherto realized.     

Sexual differences in the foraging ecology of 19th century beluga whales (Delphinapterus leucas) from the Canadian High Arctic

Marine mammals often exhibit significant sexual segregation in their diet and habitat use but these differences have not been studied systematically in historic or ancient populations due to the difficulties associated with determining the sex of skeletal elements based on gross morphology. Using a combined ancient DNA and stable isotope approach, we document a sexual difference in the foraging ecology of late 19th century beluga whales (Delphinapterus leucas) from the Canadian High Arctic. Using two PCR assays that coamplify fragments of the Y-linked SRY and X-linked ZFX genes, we assigned reproducible sex identities to 35 beluga specimens. This provided a basis for investigating sex-specific differences in foraging ecology using stable carbon and nitrogen isotope analyses of bone collagen. These isotopic data demonstrate that although both males and females primarily consumed Arctic cod, males utilized a wider range of prey than females, feeding on high trophic level benthic prey (sculpins) to a greater extent. Because bone collagen integrates prey isotopic compositions over the course of several years these sex-based differences in beluga bone collagen isotopic compositions reflect long-term and sustained sexual differences in foraging.     

Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene

The sea otter (Enhydra lutris) is a marine mammal hunted to near extinction during the 1800s. Despite their well‐known modern importance as a keystone species, we know little about historical sea otter ecology. Here, we characterize the ecological niche of ancient southern sea otters (E. lutris nereis) using δ¹³C analysis and δ¹⁵N analysis of bones recovered from archaeological sites spanning ~7,000 to 350 years before present (N = 112 individuals) at five regions along the coast of California. These data are compared with previously published data on modern animals (N = 165) and potential modern prey items. In addition, we analyze the δ¹⁵N of individual amino acids for 23 individuals to test for differences in sea otter trophic ecology through time. After correcting for tissue‐specific and temporal isotopic effects, we employ nonparametric statistics and Bayesian niche models to quantify differences among ancient and modern animals. We find ancient otters occupied a larger isotopic niche than nearly all modern localities; likely reflecting broader habitat and prey use in prefur trade populations. In addition, ancient sea otters at the most southerly sites occupied an isotopic niche that was more than twice as large as ancient otters from northerly regions. This likely reflects greater invertebrate prey diversity in southern California relative to northern California. Thus, we suggest the potential dietary niche of sea otters in southern California could be larger than in central and northern California. At two sites, Año Nuevo and Monterey Bay, ancient otters had significantly higher δ¹⁵N values than modern populations. Amino acid δ¹⁵N data indicated this resulted from shifting baseline isotope values, rather than a change in sea otter trophic ecology. Our results help in better understanding the contemporary ecological role of sea otters and exemplify the strength of combing zooarchaeological and biological information to provide baseline data for conservation efforts.     

Patterns and trends in the diet of long‐finned pilot whales (Globicephala melas) in the northeast Atlantic

There is little previous information on feeding habits of long‐finned pilot whales (Globicephala melas) in the northeast Atlantic. The present study analyzed stomach contents of pilot whales stranded in Portugal (n = 6), Galicia (northwest Spain) (n = 32), and Scotland (United Kingdom) (n = 10), from 1990 to 2011. These animals ranged from 213 to 555 cm in length (24 females, 19 males and 5 of unknown sex). The main prey identified were cephalopods of the families Octopodidae and Ommastrephidae, the former being numerically more important in Iberia (Portugal and Galicia) and the latter more important in Scotland, with Iberian whales also showing a more diverse diet. Multivariate analysis revealed evidence of geographical and seasonal variation in diet. Generalized Additive Modeling results indicated that more octopus (Eledone cirrhosa) were eaten in Iberia than in Scotland, more in the first half of the year, and more in larger whales. Numbers of ommastrephid squids in the stomach decreased over the study period and varied with season and whale length. This study confirms cephalopods as the main prey of pilot whales, as previously reported, although our results also suggest that, in the northeast Atlantic, ommastrephid squid are largely replaced as the main prey by octopods at lower latitudes.     

Gene flow on ice: the role of sea ice and whaling in shaping Holarctic genetic diversity and population differentiation in bowhead whales (Balaena mysticetus)

Sea ice is believed to be a major factor shaping gene flow for polar marine organisms, but it remains unclear to what extent it represents a true barrier to dispersal for arctic cetaceans. Bowhead whales are highly adapted to polar sea ice and were targeted by commercial whalers throughout Arctic and subarctic seas for at least four centuries, resulting in severe reductions in most areas. Both changing ice conditions and reductions due to whaling may have affected geographic distribution and genetic diversity throughout their range, but little is known about range‐wide genetic structure or whether it differed in the past. This study represents the first examination of genetic diversity and differentiation across all five putative stocks, including Baffin Bay‐Davis Strait, Hudson Bay‐Foxe Basin, Bering‐Beaufort‐Chukchi, Okhotsk, and Spitsbergen. We also utilized ancient specimens from Prince Regent Inlet (PRI) in the Canadian Arctic and compared them with modern stocks. Results from analysis of molecular variance and demographic simulations are consistent with recent and high gene flow between Atlantic and Pacific stocks in the recent past. Significant genetic differences between ancient and modern populations suggest PRI harbored unique maternal lineages in the past that have been recently lost, possibly due to loss of habitat during the Little Ice Age and/or whaling. Unexpectedly, samples from this location show a closer genetic relationship with modern Pacific stocks than Atlantic, supporting high gene flow between the central Canadian Arctic and Beaufort Sea over the past millennium despite extremely heavy ice cover over much of this period.     

Regeneration strategies of tree species in the laurel forest of Tenerife (The Canary Islands)

The laurel-forest of the Canary Islands is a montane cloud-forest. In order to gain some knowledge on the processes that maintain tree species diversity, we conducted an analysis of three different laurel-forest plots of the Anaga massif (Tenerife), varying in canopy composition but growing under similar environmental conditions. For each plot we recorded basal area of the canopy trees (h<1.30 m), the density of suckers and seedlings (h>1.30 m), as well as seed-bank composition. The plots have similar regeneration composition, which appears to be independent of differences in canopy composition. Laurus azorica is the most common seedling species, whereas Prunus lusitanica is the most abundant species among suckers and basal shoots. Neither Erica arborea nor Myrica faya, the two main canopy trees in one of the plots, were found in any of the stands as seedlings or suckers, despite their existence as viable seeds in the seed-bank. The regeneration composition and the canopy composition in one of the plots is remarkable different, revealing differents dynamics processes in the three plots. The results suggest the existence of three well-defined ecological groups: pioneer (regeneration primarily by seedlings), non-pioneer (regeneration by seedlings and suckers) and remnant species (regeneration primarily by suckers).These three groups and the effect of small scale disturbances (natural and human-induced), could help to understand the maintenance of tree species richness.     

A simple photograph‐based approach for discriminating between free‐ranging long‐finned (Globicephala melas) and short‐finned (G. macrorhynchus) pilot whales off the east coast of the United States

Line transect based abundance estimation is complicated for long‐finned (LFPW, Globicephala melas) and short‐finned (SFPW, G. macrorhynchus) pilot whales because of their similarity in appearance and their overlapping summertime range in some areas. We developed a photograph‐based approach to distinguish between species of free‐ranging pilot whales in the northwest Atlantic. We collected skin samples and photographs during the summers of 2004–2007 and used skin samples to distinguish species based on mitochondrial DNA. Relative morphometric measurements from photographs were examined using mixed‐effect models and logistic regression. The best model among 94 candidate models had an overall classification error rate of 2.5%. We tested the presence/absence of pigmentation in four regions of the dorsal body (melon, eye, cape, and saddle) for differences. Pigmentation was present in all four regions in 100% of the SFPWs sampled. Melon patch, blaze, and saddle patch pigmentation were present in 6%, 68%, and 50%, respectively, of the LFPWs, but the cape was completely absent. Both types of analyses provided positive species discrimination of free‐ranging animals. We created a cost‐effective, simple tool which could ultimately assist in providing appropriate management, mitigation, and conservation strategies for both northwest Atlantic species of pilot whales.     

Successful foraging zones of southern elephant seals from the Kerguelen Islands in relation to oceanographic conditions

Southern elephant seals, Mirounga leonina, undertake large-scale oceanic movements to access favourable foraging areas. Successful foraging areas of elephant seals from the Kerguelen Islands are investigated here in relation to oceanographic parameters. Movements and diving activity of the seals as well as oceanographic data were collected through a new generation of satellite relayed devices measuring and transmitting locations, pressure, temperature and salinity. For the first time, we have associated foraging behaviour, determined by high increased sinuosity in tracks, and dive density (i.e. number of dives performed per kilometre covered), and changes in body condition, determined by variations in drift rate obtained from drift dives, to identify the oceanographic conditions of successful foraging zones for this species. Two main sectors, one close to the Antarctic continent and the other along the Polar Front (PF), where both foraging activity and body condition increase, seem to be of particular interest for the seals. Within these regions, some seals tended to focus their foraging activity on zones with particular temperature signatures. Along the Antarctic continent, some seals targeted colder waters on the sea bottom during benthic dives, while at the PF the favourable zones tended to be warmer. The possible negative effect of colder waters in Antarctic on the swimming performances of potential fish or squid prey could explain the behaviour of elephant seals in these zones, while warmer waters within the PF could correspond to the optimal conditions for potential myctophid prey of elephant seals.     

Characterizing alloparental care in the pilot whale (Globicephala melas) population that summers off Cape Breton,Nova Scotia,Canada

Alloparental care happens when a calf is cared for by an adult that is not their parent. Although alloparental care is common in social mammals, its prevalence is difficult to assess in cetaceans, and has not been studied in Globicephala melas. A population off Cape Breton, Nova Scotia, has been studied from whale‐watching vessels since 1998, during July and August each year. From 2009 to 2011, we collected photo identifications of calves and the adults accompanying them. Alloparental care was considered to be occurring when a calf was identified with more than one companion. We found that 85.7% of calves in 2009, 80.6% of calves in 2010 and 63% of calves in 2011 had alloparents. Mothers were difficult to identify. Nevertheless, none of the other companions of calves were assigned to the same unit as the mother. Five carers were sexed, four of them males. There were no cases of within‐ or between‐year alloparental care reciprocity. It is possible that delayed reciprocity is happening on a larger time scale in this population, but the most likely explanation is that alloparental care is a byproduct of this species’ social structure, with a very small cost to the alloparent's fitness.     

Assessment of scale-dependent foraging behaviour in southern elephant seals incorporating the vertical dimension: a development of the First Passage Time method

1. Identifying the spatial scales at which top marine predators forage is important for understanding oceanic ecosystems. Several methods quantify how individuals concentrate their search effort along a given path. Among these, First-Passage Time (FPT) analysis is particularly useful to identify transitions in movement patterns (e.g. between searching and feeding). This method has mainly been applied to terrestrial animals or flying seabirds that have little or no vertical component to their foraging, so we examined the differences between classic FPT and a modification of this approach using the time spent at the bottom of a dive for characterizing the foraging activity of a diving predator: the southern elephant seal. 2. Satellite relayed data loggers were deployed on 20 individuals during three successive summers at the Kerguelen Islands, providing a total of 72 978 dives from eight juvenile males and nine adult females. 3. Spatial scales identified using the time spent at the bottom of a dive ( = 68.2 +/- 42.1 km) were smaller than those obtained by the classic FPT analysis ( = 104.7 +/- 67.3 km). Moreover, foraging areas identified using the new approach clearly overlapped areas where individuals increased their body condition, indicating that it accurately reflected the foraging activity of the seals. 4. These results suggest that incorporating the vertical dimension into FPT provides a different result to the surface path alone. Close to the Antarctic continent, within the pack-ice, sinuosity of the path could be explained by a high sea-ice concentration (restricting elephant seal movements), and was not necessarily related to foraging activity. 5. Our approach distinguished between actual foraging activity and changes in behaviour induced by the physical environment like sea ice, and could be applied to other diving predators. Inclusion of diving parameters appears to be essential to identify the spatial scale of foraging areas of diving animals.     

Leaf Gas Exchange Characteristics in Relation to Leaf Canopy Position of Myrica faya in its Native Environment (Tenerife, Canary Islands)

Abstract: Diurnal courses of gas exchange were measured throughout one year in fully expanded current-year leaves in the uppermost canopy (sun leaves, 18 m above ground) and in the lower canopy (shade leaves, 12 m above ground) of Myrica faya Ait., a dominant component of the Canarian laurel forest in Tenerife, Canary Islands, Spain.
M. faya showed large differences between sun and shade leaves in gas exchange characteristics (about 50 % of maximum carbon assimilation rate (A_max) reduction in shade leaves, but this reduction can be higher on specific days) that were modulated by strong light attenuation and high leaf area index (LAI) of the stand. This species presented low A_max, about 10 μmol m^-2 s^-1, high maximum transpiration (E, 8 mmol m^-2 s^-1) and stomatal conductance (g_s, 750 mmol m^-2 s^-1) and very low instantaneous water use efficiency (WUE, mean maximum 1.1 mmol mol^-1) and A/g_s (mean maximum 23.5 μmol mol^-1). M. faya responded to high air vapour pressure deficit (VPD), decreasing its g_s but maintaining relatively high values of A and E during the studied period. Stomatal response to VPD showed a higher sensitivity than its congeners, M. cerifera, and Laurus azorica, tree species co-occurring in the Canarian laurel forest. In general, all these gas exchange characteristics lead us to consider this species more similar to subtropical plants of humid regions than to species of the Mediterranean region.     

Site fidelity and association patterns of a rare species: Pygmy killer whales (Feresa attenuata) in the main Hawaiian Islands

Most of what we know about cetacean biology and ecology comes from studies of relatively common species. Despite their distribution throughout the tropics and sub-tropics, pygmy killer whales ( Feresa attenuata ) are rare throughout their range and are one of the most poorly-known species of odontocetes. During a 22-yr study of short-finned pilot whales ( Globicephala macrorhynchus ) off the island of Hawai'i, we opportunistically photo-identified pygmy killer whales whenever encountered. As part of a directed multi-species study throughout the main Hawaiian Islands from 2000 through 2007, we also photo-identified individuals and obtained information on habitat use and behavior. This species was extremely uncommon (representing only 1.2% of odontocete sightings in directed efforts). Given the low encounter rates, assessing trends of this population cannot be feasibly done with line-transect surveys. Despite their rarity, 80% of the distinctive individuals within groups documented off the island of Hawai'i were seen on multiple occasions, individuals were resighted over periods of up to 21 yr, and there was evidence of year-round use of the area. Association analyses indicate stable long-term associations in mixed-sex groups. High resighting rates indicate a small population of island-associated individuals that may be at risk from anthropogenic impacts.     

Genetic study of the population of Tenerife (Canary Islands,Spain): Protein markers and review of classical polymorphisms

Data on six protein polymorphisms (19 alleles) from the human population of Tenerife are presented and discussed along with other classical markers in relation to the origin of the Canarians. Genetic influences from three population groups were considered: the Iberians, and the Berbers and non-Berbers (Arabs) from north Africa. The systems examined show the Tenerife population lies within the limits of variation described for various Iberian groups, with a slight tendency towards the characteristics of north African populations. When blood groups, red cell enzymes and serum protein data were considered, the similarity of the Canary population to Iberians seems strengthened (70% estimated contribution of Iberian peninsula genes to the present-day Canarian pool), while some relation with north African groups is shown. Genetic distances between Canarians and Arabs and Canarians and Berbers are lower than those between the two north African groups, indicating a relative and comparable contribution of each to the present-day gene pool of the Canarian population. The Arab contribution could be attributable to the slaves who were introduced to these islands after the conquest in the 15th century, while the Berber contribution could be the remnants of the extinct aboriginal peoples of the islands (Guanches) or a more recent immigration due to slavery. Genetic data do not allow us to distinguish between these two possibilities. Am. J. Phys. Anthropol. 102:337–349, 1997. © 1997 Wiley-Liss, Inc.     

Parasites of Columba livia (Aves: Columbiformes) in Tenerife (Canary Islands) and their role in the conservation biology of the laurel pigeons

The prevalence and intensity of the parasites from 50 wild doves (Columba livia) from the city of Santa Cruz de Tenerife, in the island of Tenerife (Canary Archipelago), were studied. The following ectoparasites were found in apparently healthy pigeons (prevalences are shown in percentage (%) and mean intensities with their standard deviations): the acari Dermanyssus gallinae (De Geer, 1778) (6, 241.0 +/- 138.9) and Tinaminyssus melloi Fain, 1962 (10%, 218.3 +/- 117.3); the louses, Columbicola columbae Linnaeus, 1758 (100%, 111.4 +/- 76.8) and Campanulotes bidentatus Scopoli, 1763 (94%, 48.4 +/- 26.6); and the pigeon fly, Pseudolynchia canariensis Macquart, 1839 (36%, 6.2 +/- 1.6). The endoparasites we found were: a haemoprotozoan species, Haemoproteus columbae Kruze, 1890 (82%, 14.8 +/- 10.3 per 1000); coccidian oocysts, Eimeria sp. (50%, 0.2 x 10(3) +/- 1.7 x 10(3) per gr); a cestode species Raillietina micracantha (Fuhrmann, 1909) López Neyra, 1947 (44%, 12.3 +/- 9.4); and four nematode species, Tetrameres (Tetrameres) fissispina (Diesing, 1861) Travassos, 1915 (4%, 99.5 +/- 34.1), Synhimantus (Dispharynx) spiralis (Molin, 1858) (8%, 46.8 +/- 11.6), Ascaridia columbae (Gmelin, 1790) Travassos, 1913 (40%, 8.4 +/- 8.8) and Aonchotheca sp. (18%, 6.0 +/- 3.1). Several species detected in our study can be pathogens for C. bollii and C. junoniae, which are endemic pigeons of the Canary Islands, considered endangered species. Parasites (ectoparasites, protozoa and helminths) of C. livia found in Tenerife and others from wild and farm birds in the island were considered as healthy controls.     

High site fidelity,strong associations,and long‐term bonds: Short‐finned pilot whales off the island of Hawai‘i

Studies of short‐finned pilot whales suggest they travel in stable mixed‐sex groups composed of strongly associated individuals; however, temporal analyses of social structure are lacking. To examine site fidelity, association patterns, and temporal relationships, we analyzed data from 267 encounters of this species off the island of Hawai‘i from 2003 through 2007, identifying 448 distinctive individuals (68.1% seen more than once). About 72% of the whales were linked by association into a single social network, suggesting the possibility of multiple populations using the area. Sighting histories suggested that only some individuals exhibit high site fidelity. Individuals demonstrated preferential associations and community division was strongly supported by average‐linkage hierarchical cluster analysis of the association data. Nine longitudinally stable social units composed of key individuals and their constant companions were identified. Qualitative assignment of age and sex classes of unit members indicated that some segregation between adult males and female/calf pairs may occur. Temporal analyses of individuals encountered on the same day indicate stable long‐term associations. Differential patterns of residency and site fidelity were unexpected and may be indicative of multiple populations around the main Hawaiian Islands. The presence of a resident population demonstrating strong, long‐term site fidelity and associations off Hawai‘i Island may warrant special management considerations.     

A molecular study of hybridization and homoploid hybrid speciation in Argyranthemum (Asteraceae) on Tenerife,the Canary Islands

Examples of recurrent homoploid hybrid speciation are few. One often‐cited example is Argyranthemum sundingii. This example includes two described species, A. lemsii and A. sundingii, resulting from reciprocal hybridization between A. broussonetii and A. frutescens on Tenerife. The four species and artificial F₁ and F₂ hybrids have previously been investigated morphologically and cytologically. Here, we examine population differentiation based on amplified fragment length polymorphism to get a better understanding of the genetic relationships among the species and the extent of hybridization. We aim to investigate if there is molecular support for treating the hybrid species as one taxon. Seven parental and four hybrid species populations (149 individuals) were analysed and we scored 85 polymorphic markers. A few (2–5) were private to each species but variably present and mostly rare. Our principal coordinate, STRUCTURE and BAPS analyses and AMOVA resulted in a clear separation of the parental species. The hybrid species were genetically less divergent but not identical. Our data indicate that hybridization and introgression are common in all these species on Tenerife and support the hypothesis that homoploid hybrid speciation has occurred repeatedly. Intrinsic post‐zygotic barriers are notoriously weak in Argyranthemum and reproductive isolation and speciation result primarily from strong ecological selection. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 19–31.     

How to define nativeness in vagile organisms: lessons from the cosmopolitan moss Bryum argenteum on the island of Tenerife (Canary Islands)

The distinction between native and introduced biotas presents unique challenges that culminate in organisms with high long‐distance dispersal capacities in a rapidly changing world. Bryophytes, in particular, exhibit large distribution ranges, and some species can truly be qualified as cosmopolitan. Cosmopolitan species, however, typically occur in disturbed environments, raising the question of their nativeness throughout their range. Here, we employ genetic data to address the question of the origin of the cosmopolitan, weedy moss Bryum argenteum on the island of Tenerife. The genetic diversity of B. argenteum on Tenerife was comparable to that found in continental areas due to recurrent colonisation events, erasing any signature of a bottleneck that would be expected in the case of a recent colonisation event. The molecular dating analyses indicated that the first colonisation of the island took place more than 100,000 years ago, i.e. well before the first human settlements. Furthermore, the significant signal for isolation‐by‐distance found in B. argenteum within Tenerife points to the substantial role of genetic drift in establishing the observed patterns of genetic variation. Together, the results support the hypothesis that B. argenteum is native on Tenerife; although the existence of haplotypes shared between Tenerife and continental areas suggests that more recent, potentially man‐mediated introduction also took place. While defining nativeness in organisms that are not deliberately introduced, and wherein the fossil record is extremely scarce, is an exceedingly challenging task, our results suggest that population genetic analyses can represent a useful tool to help distinguish native from alien populations.