Native Geographic Range Research Articles

Helminth parasites of Artemia franciscana (Crustacea: Branchiopoda) in the Great Salt Lake, Utah: first data from the native range of this invader of European wetlands.

The present study is the first survey on the role of Artemia franciscana Kellogg as intermediate host of helminth parasites in its native geographical range in North America (previous studies have recorded nine cestode and one nematode species from this host in its invasive habitats in the Western Mediterranean). Samples of Artemia franciscana were collected from four sites in the Great Salt Lake (GSL), Utah, across several months (June-September 2009). A. franciscana serves as intermediate host of five helminth species in this lake. Four of them are cestodes: three hymenolepidids, i.e. Confluaria podicipina (Szymanski, 1905) (adults parasitic in grebes), Hymenolepis (sensu lato) californicus Young, 1950 (adults parasitic in gulls), Wardium sp. (definitive host unknown, probably charadriiform birds), and one dilepidid, Fuhrmannolepis averini Spassky et Yurpalova, 1967 (adults parasitic in phalaropes). In addition, an unidentified nematode of the family Acuariidae was recorded. Confluaria podicipina is the most prevalent and abundant parasite at all sampling sites, followed by H. (s. l.) californicus. The species composition of the parasites and the spatial variations in their prevalence and abundance reflect the abundance and distribution of aquatic birds serving as their definitive hosts. The temporal dynamics of the overall helminth infections exhibits the highest prevalence in the last month of study at each site (August or September). This native population of A. franciscana from GSL is characterised with higher prevalence, intensity and abundance of the overall cestode infection compared to the introduced populations of this species in the Palaearctic Region. The values of the infection descriptors in the native population of A. franciscana are slightly lower or in some cases similar to those of the Palaearctic species Artemia parthenogenetica Barigozzi (diploid populations) and Artemia salina (Linnaeus) in their native habitats.

Influence of ecological factors on the production of active substances in the anti-cancer plant Sinopodophyllum hexandrum (Royle) T.S. Ying.

The quality of traditional Chinese herbal medicine, which plays a very important role in the health system of China, is determined by the active substances produced by the plants. The type, content, and proportion of these substances may vary depending on ecological factors in areas where the plants are grown. Sinopodophyllum hexandrum (Royle) T.S. Ying, an endangered plant species with great medical value, was investigated in eight production locations representative of its natural geographical distribution range in China. The correlation between the contents of the active ingredients extracted from the roots and rhizomes of S. hexandrum and the ecological factors were evaluated step-by-step using a series of computational biology methodologies. The results showed that ecological factors had significant effects on the contents but not on the types of the active ingredients in eight production locations. The primary ecological factors influencing the active substances included the annual average precipitation, July mean temperature, frost-free period, sunshine duration, soil pH, soil organic matter, and rapidly available potassium in the soil. The annual average precipitation was the most important determinant factor and was significantly and negatively correlated with the active ingredient contents (P < 0.001). In contrast, organic matter was the most important limiting factor and was significantly and positively correlated with the active substances. These ecological factors caused 98.13% of the total geographical variation of the active ingredient contents. The climate factors contributed more to the active ingredient contents than did the soil factors. It was concluded that from the view of the contents of the secondary metabolites and ecological factors of each growing location, in Jingyuan, Ningxia Province, and Yongdeng, Gansu Province, conditions were favorable to the production of podophyllotoxin and lignans, whereas in Shangri-La, Yunnan Province, and Nyingchi, Tibet, conditions were favorable to the production of quercetin and kaempferol.

Genome size variation in gymnosperms under different growth conditions

The genome is structurally and functionally influenced by ecological factors during adaptive processes. Several natural factors can cause this, and here we present the effects of different growth conditions on the genome size. Genome size assessments were carried out by flow cytometry for a set of 19 taxa for each of three growing conditions: (i) wild plants growing in their natural habitats used as a control group; (ii) potted plants; and (iii) bonsai plants. Our results show a large variation in the genome size of bonsai and potted plants compared to their wild representatives. The most important conclusion is that 1Cx values measured in potted plants can be up to 8.48% lower and in bonsai plants up to 26.83% higher than the values assessed for the respective wild individuals. In the case of Juniperus thurifera, this divergence largely exceeded the genome size variation previously estimated along the natural geographical range of the species. Such deviation from expected values could be interpreted as genuine genome size variation, or to result from biochemical or/and DNA compactness changes triggered by growth conditions. The present results provide evidence for plant response to human-induced environmental changes, thus making the current approach potentially interesting for the prediction of the influence of climate change on plants and for other applications.

New floristic records from the Polish part of the Lithuanian Lakeland (NE Poland)

This paper provides a floristic list of 111 vascular plant species recorded in the Polish part of the Lithuanian Lakeland in 2012-2014, using the ATPOL cartogram method. There are 36 native species, 53 established alien species, and 22 casual alien species. Among the established alien species there are 13 species native to Poland which have no natural geographical range in the Polish part of the Lithuanian Lakeland, and they appear to be kenophytes on a regional scale. 16 species are new to the regional flora. Some of the most interesting are: Amaranthus albus, Anthemis ruthenica, Avena strigosa, Bromus benekenii, Cam­ panula rapunculus, Erysimum hieraciifolium, Nonea pulla, Seseli annuum, Sisymbrium strictissimum, Stachys annua, and Tragopogon dubius.

Discovery of Two Aleocharine Staphylinid Species (Coleoptera) Associated with Coptotermes formosanus (Isoptera: Rhinotermitidae) from Central Japan, with a Review of the Possible Natural Distribution of C. formosanus in Japan and Surrounding Countries

Two termitophilous staphylinid beetles, Japanophilus hojoi Maruyama &amp; Iwata and Sinophilus yukoae Maruyama &amp; Iwata (Staphylinidae: Aleocharinae) are known to inhabit nests of a termite species, Coptotermes formosanus Shiraki (Rhinotermitidae). Previously, these beetles had only been collected from C. formosanus nests in the Nansei Archipelago, between Kyushu and Taiwan. Here, were report their existence in nests in the coastal regions of Wakayama Prefecture, Central Japan. A review of published records strongly supports the hypothesis that Nansei Archipelago, Kyushu and the coastal areas of Kii Peninsular of Honshu, constitute, at least, part of the natural geographic range of C. formosanus.

Rewiring the wheat reproductive system to harness heterosis for the next wave of yield improvement.

Bread wheat (hexaploid Triticum aestivum) provides an extraordinary 10,000-y story of a new species, established by early farmers, selecting for simple agronomical traits to facilitate efficient and plentiful grain harvest. The genetic changes underlying wheat domestication over thousands of years, however, included not just a collection of beneficial single gene mutations, but also introgressions and whole genome duplication. The hexaploidization event occurred spontaneously in nature, but the resulting wild species did not survive; it is known only in its domesticated form. Evolutionary bottleneck(s) reduced genetic variation of the species, and it was introduced broadly outside its native geographical range and habitat. Nevertheless, modern breeding programs delivered high-yield elite cultivars, which are planted in most major wheat-producing areas of the world. In the face of quickly declining arable land expansion and challenges from climate change, the following question arises: where can we find the next wave of increase in yield and global production of wheat? In PNAS, Kempe et al. (1) describe molecular engineering of an elegant male sterility–fertility restoration system for the exploration of heterosis (hybrid plant vigor) in wheat. In the future, this system could facilitate introduction of hybrid seeds on a large scale.

Growth Response of Juvenile Walleyes after Cold Banking

AbstractThe natural geographical range of Walleye Sander vitreus extends to northern latitudes where lakes are often ice covered for 8 months. Their adaptation to long intervals at low temperature provides aquaculturists the opportunity to purposefully maintain Walleyes in confinement for several months at low temperatures with minimal feeding, i.e., a protocol termed cold banking (CB). To be successful, CB should not result in substantial mortality or loss of body condition, and after CB interval, fish should show a strong positive growth response. The objective of this study was to determine the growth response and condition of fingerling Walleyes cold banked, for 125 d at mean temperature of 6.9°C, in a 76‐d post‐CB (PCB) interval. Survival in the CB interval was 99%, and means of initial and final length, weight (4.5% loss), and relative weight (Wr) were not significantly different. After a 4‐d transition from 5.1°C to 19.2°C, some CB Walleyes were cultured in a water reuse aquaculture system at mean temperature of 22.6°C for 76 d. In the PCB interval, fish length increased 31%, and weight 170%, and Wr was 99.8. This study demonstrates that CB did not result in substantial mortality or weight loss, and Walleyes show a strong PCB growth response after cold banking.

European newts establish in Australia, marking the arrival of a new amphibian order

We document the successful establishment of a European newt (Lissotriton vulgaris) in south-eastern Australia, the first recorded case of a caudate species establishing beyond its native geographic range in the southern hemisphere. Field surveys in south-eastern Australia detected L. vulgaris at six sites, including four sites where the species had been detected 15 months earlier. Larvae were detected at three sites. Individuals had identical NADH dehydrogenase subunit 2 and cytb mtDNA gene sequences, and comparisons with genetic data from the species’ native range suggest that these individuals belong to the nominal subspecies L. v. vulgaris. Climatic conditions across much of southern Australia are similar to those experienced within the species’ native range, suggesting scope for substantial range expansion. Lissotriton vulgaris had been available in the Australian pet trade for decades before it was declared a ‘controlled pest animal’ in 1997, and thus the invasion documented here likely originated via the release or escape of captive animals. Lissotriton vulgaris is the sole member of an entire taxonomic order to have established in Australia, and given the potential toxicity of this species, further work is needed to delimit its current range and identify potential biodiversity impacts.

Patterns of non-randomness in the composition and characteristics of the Taiwanese bird trade

The invasion pathway is composed of a sequential series of stages that need to be quantified separately in order properly to understand the invasion process. Here, we examine the composition and characteristics of bird species being sold in the pet bird market in Taiwan. The bird trade in Taiwan is of high volume and financially lucrative. The identity of species in this trade is vital for informing later stages (introduction, establishment, spread) of the invasion pathway. We conducted interviews and surveys of 72 outlets selling pet birds from seven cities across Taiwan, from which we identified 247 bird species (within 34 families) for sale. Of these, 170 bird species (from 27 families) are exotic to Taiwan. Using randomization tests, we show that nine families are significantly over-represented in the pet trade (Psittacidae, Muscicapidae, Timaliidae, Sturnidae, Turdidae, Estrildidae, Chloropseidae, Zosteropidae and Fringillidae), and three after sequential Bonferroni correction (Psittacidae, Muscicapidae and Sturnidae). Species that have been identified in Taiwanese pet shops tend to have a larger native geographic range, originate further from the equator, are smaller-bodied, and have more aesthetically-pleasing songs than expected by chance. The native ranges of pet shop species are more likely to be situated in the Indo-Malay and Palearctic biogeographic realms, while fewer species than expected derive from the Neotropic, Afrotropic and Nearctic realms. Our results show that bird species for sale in Taiwan are determined by the interaction of species availability and societal demands.

Patterns of transport and introduction of exotic amphibians in Australia

AbstractAimResearch on amphibian invasions has largely focused on the likelihood of successful establishment, while analysis of the previous stages in the invasion pathway (transport and introduction) is scarce despite its critical importance. Here, we investigate the patterns of taxonomic and geographic non‐randomness as well as the factors affecting the transport and introduction of amphibians.LocationAustralia.MethodsWe compiled and analysed a database on the identity of transported and introduced amphibians. First, we tested for taxonomic (family level) and geographic non‐randomness by comparing transported and introduced species with all extant caudates and anurans. Second, we constructed models to examine the influence of different factors upon the probability of transport and introduction of amphibians in Australia.ResultsAmphibians were transported via two main pathways: trade (71 species) and stowaway (38 species). In addition, several species were transported through both pathways. Transported species represented a taxonomic and geographic non‐random sample of all extant amphibian species. Conversely, introduced species constituted a random sample of the transported amphibians. Regardless of the transport pathway, the probability of transport of amphibians increased with increasing extent of their native geographical range. A large number of native Australian species have been transported outside their naturally occurring ranges, representing over 65% of the introduced species. Introduction is strongly correlated with the transport pathway, that is, species transported through two pathways were more likely to be released or escape from captivity.Main conclusionsThe probability of amphibians being transported and introduced to, or within, Australia is critically affected by their availability to be captured, bred and housed in captivity. Management strategies to prevent the future introduction and establishment of new amphibians need to include the people involved in species trade, as well as continued vigilance by biosecurity and custom agencies.

Behavioural flexibility allows an invasive vertebrate to survive in a semi-arid environment

Plasticity or evolution in behavioural responses are key attributes of successful animal invasions. In northern Australia, the invasive cane toad (Rhinella marina) recently invaded semi-arid regions. Here, cane toads endure repeated daily bouts of severe desiccation and thermal stress during the long dry season (April-October). We investigated whether cane toads have shifted their ancestral nocturnal rehydration behaviour to one that exploits water resources during the day. Such a shift in hydration behaviour could increase the fitness of individual toads by reducing exposure to desiccation and thermal stress suffered during the day even within terrestrial shelters. We used a novel method (acoustic tags) to monitor the daily hydration behaviour of 20 toads at two artificial reservoirs on Camfield station, Northern Territory. Remarkably, cane toads visited reservoirs to rehydrate during daylight hours, with peaks in activity between 9.00 and 17.00. This diurnal pattern of rehydration activity contrasts with nocturnal rehydration behaviour exhibited by adult toads in their native geographical range and more mesic parts of Australia. Our results demonstrate that cane toads phase shift a key behaviour to survive in a harsh semi-arid landscape. Behavioural phase shifts have rarely been reported in invasive species but could facilitate ongoing invasion success.

Surviving in the south: a recent incursion of the agile wallaby (Macropus agilis) in Tasmania

The agile wallaby (Macropus agilis) has established in a small area of coastal plain on the central east coast of Tasmania. The Tasmanian occurrence is the only known population of this species outside its natural geographical range. The current wild population is likely to have originated from a small number of individuals that escaped or were released from a nearby wildlife park in the late 1990s. The population is successfully reproducing although it appears to be relatively small and restricted. A precautionary approach is needed and the eradication of the population is recommended.

Macroecology meets invasion ecology: performance of Australian acacias and eucalypts around the world revealed by features of their native ranges

Native geographical range extent has frequently emerged as a correlate of invasiveness, especially for plant species. We tested whether dimensions of the native range (measured by the area-of-occupancy and its scaling patterns) of 720 Australian eucalypts (genera Angophora, Eucalyptus and Corymbia) could explain introduction and invasion success. We also compared our results with a previous study on 979 Australian acacias (previously grouped in Acacia subgenus Phyllodineae) to investigate whether features of their native ranges explained the much higher invasion success in this group compared to eucalypts. From nine databases we found records that 373 eucalypts have been introduced to areas outside their native ranges; 82 of these have become naturalised, and eight are invasive. A similar proportion of Australian acacias have been introduced, but almost three times as many are invasive (384 species introduced, 71 of which are naturalized and 23 invasive). Eucalypts with large native ranges are more likely to have been introduced and subsequently naturalise, as is the case with acacias. Unlike acacias, however, the native range size of invasive eucalypts was not significantly greater than naturalised (but not invasive) species. Intriguingly, the human preference for introducing species with larger ranges was much greater for acacias than for eucalypts as the geometric mean range sizes of introduced, naturalised and invasive acacias are 2.04, 1.88 and 3.59 times those of eucalypts at the same stage. Moreover, the percolation exponent (i.e. the slope of occupancy scaling) becomes more extreme towards the end of the introduction–naturalization–invasion continuum, decreasing for acacias but increasing for eucalypts, with acacias, except for non-introduced species, having a lower exponent than eucalypts. The selection preference of acacias during introduction is thus for species that can rapidly expand their range; in contrast, slow-spreading eucalypts have been selected for dissemination. In other words, humans appear to have selected for highly invasive acacias but against introducing highly invasive eucalypts.

Do Japanese eels recruit into the Japan Sea coast?: A case study in the Hayase River system, Fukui Japan

The Japanese coastlines along the Sea of Japan (Japan Sea) have been thought to be one of the margins of the distribution range of the Japanese eel Anguilla japonica, and there is evidence that eels had naturally recruited into these areas several hundred years ago. However, recruitment there is uncertain recently, because there seems to be no study that reported glass eel or elver recruitment into the coasts along the Japan Sea for a couple of decades, and the eels inhabiting these areas were probably stocked by fisheries cooperatives. In order to improve understanding of the present-day natural geographic distribution range of this species, we searched for naturally recruited wild eels in the Hayase River system, Fukui Prefecture, which flows into the Japan Sea. Multiple approaches including investigation of glass eel recruitment, comparison of body size, and estimation of habitat use types was employed. During the observation period (from January to July 2010), no glass eels were found at the river mouth of the Hayase River in monthly sampling. Of eels collected in this study (n = 127), no eels smaller than the initial body size of eels for stocking were found in this water system and none were identified as being of wild origin based on the habitat use type classifications from otolith microchemistry (n = 48). This lack of evidence of Japanese eels recruiting into Japan Sea coast waters suggests most eels present there may be stocked eels. Japanese eels could have been distributed naturally along the Japan Sea coast more than in recent years, indicating a possible decrease of the natural distribution range of this species.

Speciation in the asexual realm: Is the parthenogenetic weevil Naupactus cervinus a complex of species in statu nascendi?

Population genetic theory shows that asexual organisms may evolve into species, which behave as independent evolutionary units. As a result, they form genotypic clusters separated by deep gaps due to geographic isolation and/or divergent selection.Identification of several genetically divergent groups of weevils embodied in the nominal species Naupactus cervinus deserves further study, in order to test if these lineages are evolving independently. In the present paper we tested if the parthenogenetic weevil N. cervinus, native to South America and broadly distributed throughout the world, contains more than one evolutionary unit. For this purpose, we applied three different approaches, a multilocus phylogenetic analysis, the GMYC approach and the K/θ method. We accomplished these analyses through a survey of mitochondrial (COI and COII genes) and nuclear (ITS1 sequence) genetic variation and morphometric analysis in a sample which included individuals from different locations within the native geographic range of N. cervinus. In addition, we compared the divergence accumulated in this species with that in another weevil of the same tribe (Naupactini) showing identical reproductive mode to see if similar levels of morphological variation matches similar levels of genetic divergence.We report the presence of two independent evolutionary units living in sympatry in forest areas. The incongruence between mitochondrial and nuclear datasets analyzed herein reflects incomplete lineage sorting of the nuclear marker and different evolutionary rates between genomes.Ecological divergence driven by natural selection (sympatry) or secondary contact after geographic isolation (allopatry) might explain the deep gaps in mitochondrial phylogenies. Instead, Wolbachia infection was ruled out as a causal factor for such differentiation. We conclude that N. cervinus is probably a species complex with at least two well differentiated lineages that would represent a cluster of species in statu nascendi.

Evidence of low-levels of natural introgression between Pinus jaliscana and Pinus oocarpa in an open-pollinated progeny trial using near-infrared spectroscopy

There have been no reports of natural introgression between Pinus jaliscana and Pinusoocarpa where they occur sympatrically in the highlands of western Mexico. However, a small number of putative hybrid trees were observed in a progeny trial of 57 open-pollinated families of P. jaliscana at De Rust, South Africa that represented all nine known natural populations of the species in its native geographic range. The objectives of the study were to confirm hybridity using traditional botanical analysis of needle traits (no cones were available) and once admixtures were confirmed to develop near infrared spectroscopy (NIRS) models to define the spectral signature of “pure P. jaliscana” and the hybrid. The calibration models were then run on a large subsample of 260 trees that served as a validation data set to predict the range-wide occurrence of introgression in P. jaliscana. The calibration data set for the NIRS included 57 pure P. jaliscana and 31 hybrid trees identified in the trial that were morphologically separated using canonical analysis based on four external needle traits: number of needles per fascicle, needle length, needle width, fascicle sheath length and three needle color traits: hue, value and chroma. NIRS models were developed using 1g of ground, oven-dried needles/tree that were scanned at visible and NIR wave lengths between 400 and 2500nm. The raw spectral data, log(1/reflectance) were processed using standard normal variate and de-trending transformations. The NIRS calibration model identified six hybrid trees in the validation population for an overall species admixture rate of 2.3% versus 7.7% based on subjective scoring in the field. The implications of P. oocarpa introgression in P. jaliscana in natural stands in western Mexico are discussed. NIRS provides a quick way to obtain reasonable estimates of species admixtures in progeny trials and is an inexpensive surrogate to using molecular markers. NIRS seems most practical when species are very closely related and/or there is unbalanced representation of parental species in progeny tests to make comparisons with putative hybrids difficult.

High phenotypic variation of seed traits, germination characteristics and genetic diversity of an invasive annual weed

AbstractBoth phenotypic and genetic variation can affect the establishment success of exotic species. Using the weed Senecio vernalis Waldst. &amp; Kit. with a continuous westward expansion of the native geographic range, we asked to what degree seed traits and germination patterns differ among different habitat disturbance types in the introduced region. We hypothesized that seed traits and germination pattern differ between different disturbance types, with lighter seeds and enhanced germination speed in highly disturbed habitats. Since S. vernalis colonizes successfully various disturbed habitats, we expected to find a high phenotypic genetic variation. Individuals from 19 populations were sampled from one region in Eastern Germany to study seed trait variation and germination success by means of a germination experiment and to assess genetic patterns using amplified fragment length polymorphism (AFLP) markers. Contrary to our expectation, habitat disturbance types did not differ in seed traits, germination characteristics or genetic variation. Instead, we found highest phenotypic and genetic variation within populations. Maximum percentage of germination was positively affected by seed mass. In addition, there was a weak but significant association between AFLP band patterns and population size and seed width, indicating that some variation in seed traits has a genetic component. In conclusion, the absence of a population differentiation at this geographic scale makes it unlikely that adaptation to different disturbance regimes is involved. Instead, a high variation in seed traits, overall high germination and genetic variation within populations under a wide range of habitat disturbance conditions seems to enable the offspring to colonize various habitat disturbance types.

The Bacterial Composition within the Sarracenia purpurea Model System: Local Scale Differences and the Relationship with the Other Members of the Food Web

The leaves of the carnivorous pitcher plant, Sarracenia purpurea, contain a microscopic aquatic food web that is considered a model system in ecological research. The species identity of the intermediate and top trophic level of this food web, as well the detritivore midge, are highly similar across the native geographic range of S. purpurea and, in some cases, appear to have co-evolved with the plant. However, until recently, the identity, geographic variation, and diversity of the bacteria in the bottom trophic level of this food web have remained largely unknown. This study investigated bacterial community composition inside the leaves of S. purpurea to address: 1) variation in bacterial communities at the beginning of succession at the local scale in different areas of the plant’s native geographic range (southern and mid-regional sites) and 2) the impacts of bacterial consumers and other members of the aquatic food web (i.e., insects) on bacterial community structure. Communities from six leaves (one leaf per plant) from New York and Florida study sites were analyzed using 16S ribosomal RNA gene cloning. Each pitcher within each site had a distinct community; however, there was more overlap in bacterial composition within each site than when communities were compared across sites. In contrast, the identity of protozoans and metazoans in this community were similar in species identity both within a site and between the two sites, but abundances differed. Our results indicate that, at least during the beginning of succession, there is no strong selection for bacterial taxa and that there is no core group of bacteria required by the plant to start the decomposition of trapped insects. Co-evolution between the plant and bacteria appears to not have occurred as it has for other members of this community.

Narrow phylogeographic origin of five introduced populations of the Siberian chipmunk Tamias (Eutamias) sibiricus (Laxmann, 1769) (Rodentia: Sciuridae) established in France

Large native geographical range and number of introduction events are often invoked to explain the successful establishment of alien mammal species. To infer the native geographic range of the Siberian chipmunks Tamias (Eutamias) sibiricus (Lax.) invasion in France, we identified the subspecies that individuals sampled in 5 out of the 11 established populations belonged. Based on craniometrical measures, variation in the mtDNA sequence of the cytochrome b, and alarm call sonogram shape, all French specimens were members of T. (E.) s. barberi which has the smallest geographical range (Korean peninsula) of the three recognized subspecies. An intense pet trade between European countries and Korea until the 1980’s best explains the success in establishment of this small ground-squirrel in France, where it was released mainly by private owners. Size of the native geographical range should be interpreted with caution in explaining the establishment of an invasive species, at least without a precise knowledge of its introduction pathways and taxonomic status.

Plasma 25-hydroxyvitamin D3 concentrations in Hermann's tortoises (Testudo hermanni) exposed to natural sunlight and two artificial ultraviolet radiation sources

Objective-To determine the effect of various UVB radiation sources on plasma 25-hydroxyvitamin D(3) concentrations in Hermann's tortoises (Testudo hermanni). Animals-18 healthy Hermann's tortoises. Procedures-Tortoises were exposed to sunlight in an outdoor enclosure located in the natural geographic range of Hermann's tortoises (n = 6 tortoises) or a self-ballasted mercury-vapor lamp (6) or fluorescent UVB-emitting lamp (6) in an indoor enclosure for 35 days. Plasma samples were obtained from each tortoise on the first (day 0) and last (day 35) days of the study, and concentrations of 25-hydroxyvitamin D(3) were determined. Amount of UVB radiation in enclosures was measured. Results-Mean ± SD plasma 25-hydroxyvitamin D(3) concentrations for tortoises exposed to the mercury-vapor and fluorescent lamps were significantly lower on day 35 (155.69 ± 80.71 nmol/L and 134.42 ± 51.42 nmol/L, respectively) than they were on day 0 (368.02 ± 119.34 nmol/L and 313.69 ± 109.54 nmol/L, respectively). Mean ± SD plasma 25-hydroxyvitamin D(3) concentration for tortoises exposed to sunlight did not differ significantly between days 0 (387.74 ± 114.56 nmol/L) and 35 (411.51 ± 189.75 nmol/L). Mean day 35 plasma 25-hydroxyvitamin D(3) concentration was significantly higher for tortoises exposed to sunlight versus those exposed to mercury-vapor or fluorescent lamps. Sunlight provided significantly more UVB radiation than did the mercury-vapor or fluorescent lamps. Conclusions and Clinical Relevance-Plasma 25-hydroxyvitamin D(3) concentrations differed between tortoises exposed to sunlight and those exposed to artificial UVB sources. Exposure to sunlight at a latitude similar to that of the natural geographic range is recommended for healthy and calcium-deficient tortoises.