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1.
Pathogens such as rabies virus and canine distemper virus present a significant risk to the long-term survival of some endangered African wild dog (Lycaon pictus) populations. Vaccination of wild dogs is one approach that might reduce population extinction risks; however clear guidelines for how best to do this are lacking. Hence, we developed a mathematical model of wild dog population dynamics that integrates a pathogen transmission model and a vaccination process. Simulations indicated that the most effective vaccination strategy includes all age classes (when pups are 2-months old), prioritizes the breeding pair, and vaccinates at least 4 animals per pack included in the vaccination effort. In addition, populations for which an Allee effect, high rates of pathogen introduction, or low rates of recovery and immunity were simulated, required greater vaccination coverage (dogs/pack), to protect an equivalent number of packs compared to populations for which no Allee effect, low rates of pathogen introduction, or high rates of recovery and immunity were simulated. For populations in which some packs (high-risk) have a greater risk of pathogen exposure than others (low-risk), vaccinating both high- and low-risk packs, or only low-risk packs, is more effective than vaccinating only high-risk packs when pathogen introduction rates are high. Finally, model results suggest that vaccination of wild dog populations against pathogens, such as canine distemper virus, that do not cause 100% mortality and against which some wild dogs develop acquired immunity, may be unnecessary. 相似文献
2.
Rabies is a fatal zoonotic disease of mammals; it exacerbates the uncertainty of conserving populations of some threatened mammals (TM). Modelling affords an inexpensive, a priori way of studying key parameters of wildlife rabies transmission, rabies management economics, and TM conservation. Numerous models of rabies transmission have been published. Linear density dependent models predicted that a threshold density (KT ? 1.0), possibly attained by culling or contraception, would eliminate an epizootic through reduced contacts among host animals. Density independent models predicted less advantage of culling and contraception in rabies control due to limited contacts among territorial host animals. Recent stochastic, mixed models offer novel predictions about the role of culling, fertility control, and oral rabies vaccination (ORV) in disease management. Use of a “threshold successful contact” rate (CT) as a parameter in these models predicts that density reduction of host animals will enhance ORV campaigns in non-TM contexts via more efficient bait delivery and vaccination. Economic analyses of medical, public health, and veterinary costs have shown post-exposure prophylaxis (PEP) and increased pet vaccinations (PV) to be major rabies-caused expenses during and after epizootics in North America. No modelling efforts have examined either the benefits-costs of rabies management strategies to conserve TM or the use of ORV, per se, to conserve TM - an omission due in part to the lack of methodologies for properly valuing TM (potential savings) and the expense or lower priority of using ORV for TM protection. This paper: (1) describes key aspects of rabies-transmission models in wildlife, (2) posits the use of CT to predict disease persistence, (3) reviews selected ORV strategies, economic studies, and benefit-cost models associated with the use of ORV as a means of rabies control in non-TM situations, (4) discusses implications of these models to the conservation of TM, and (5) recommends five steps to improve modelling of rabies transmission (wildlife disease in general), rabies-control economics, and TM conservation. 相似文献
3.
D.A. Randall J. Marino D.T. Haydon D.L. Knobel L.A. Tallents D.W. Macdonald M.K. Laurenson 《Biological conservation》2006,131(2):151-162
Infectious diseases pose an important extinction risk for a number of endangered carnivore populations. Wild canids are particularly susceptible to generalist pathogens transmitted from domestic dogs - particularly rabies virus and canine distemper virus (CDV). Here we present a review of rabies as a threat to Ethiopian wolves, an endangered canid restricted to a few isolated Afro-alpine ranges in the Ethiopian highlands, and the impact of rabies on the largest population in the Bale Mountains. In the Bale Mountains, two confirmed rabies outbreaks among Ethiopian wolves in 1991-1992 and 2003-2004 were each responsible for over 70% mortality among focal packs and a third rabies outbreak was suspected in 1990. This review also presents an integrated disease management strategy for Ethiopian wolves combining long-term population monitoring, disease surveillance, conventional and emergency vaccination programs, and advanced modelling techniques. 相似文献
4.
Conservation of rare species is frequently complicated by their narrow niches and poor competitive abilities which limit their distribution to a few small populations. We studied how population size and structure of an endemic cycad of northwestern Mexico, Dioon sonorense, known to be threatened by widespread land conversion and plant extraction by humans, varied with 21 environmental variables. We also used matrix population models to show how population structure may affect its long-term persistence. Slope and soil exchangeable potassium explained a moderate proportion of the variance in the abundance of adult individuals, while abundance of adults and slope explained a large proportion of the variance in the abundance of seedlings. The strong non-linear relationships of seedling abundance with slope and adult abundance suggest threshold effects that may limit D. sonorense regeneration in less suitable environments. Modeling suggests that most of the study populations will not be viable in the long-term, except for the largest population. Modeling scenarios with large increments in fecundity and seedling survival produced modest gains in population growth. The long-term persistence of D. sonorense is shown in our study to be further threatened by: (a) small size of adult populations, (b) low-quality habitat in which most populations occur, and potentially, (c) the combined effect of low fecundity and recruitment. 相似文献
5.
While conservation management is increasingly turning towards an ecosystem-level framework, the focus on a small subset of surrogate species has recognised merit given insufficient time, resources, and expertise. The kaka (Nestor meridionalis), a large threatened New Zealand parrot, is an iconic, visible species in lowland forests. As kaka populations are sensitive to mustelid predation and habitat loss, kaka can act as both a flagship and indicator species for healthy lowland forest ecosystems in New Zealand. To ensure the sustained protection of kaka over a sufficient area, this research aims to estimate the minimum viable population (MVP) size of kaka in the Eglinton Valley, Fiordland, and the management required for population persistence. A post-breeding census, stochastic, age structured Leslie matrix model was developed to estimate the population size having a 95% probability of persistence over 100 years. Scenarios modeling current and alternate management regimes, uncertain life-history traits, and environmental unpredictability were run. The most ‘realistic’ scenario resulted in an MVP size of 258 kaka (155 adults). Maintaining current levels of predator control appears essential to ensure kaka population persistence. An area of >500 km2 is proposed to maintain the MVP of kaka based on detailed information on home range size and territory overlap derived from radio-tracking studies. As one of a group of surrogate species in lowland forest ecosystems, kaka may be used to guide management decisions regarding large-scale mustelid trapping and the delineation of habitat area requiring protection in the face of proposed human developments in the region. 相似文献
6.
The monophagous flightless weevil Hadramphus spinipennis causes the frequent local extinction of its host plant Aciphylla dieffenbachii through overexploitation. Both species are endemic and restricted to the Chatham Islands group (New Zealand). The weevil is classified as endangered and the plant as a threatened species. As this herbivore-plant system is locally unstable long-term persistence only appears possible via a metapopulation structure in which subpopulations are connected by dispersal. This paper investigates this hypothesis using a spatially explicit model of a consumer population whose resource is patchily distributed. The parameters are adapted to the H. spinipennis-A. dieffenbachii system. Our model includes local population dynamics and dispersal of the consumer, the destruction of host plant patches due to foraging and their regeneration. The results show that the key factor for long-term persistence is the short-range dispersal of the consumer with high mortality during dispersal. Only this highly inefficient dispersal prevents the synchronisation of local dynamics while ensuring sufficient colonisation of regenerated patches. We also show that although synchronisation through spatially correlated environmental fluctuations may be critical for long-term persistence, it cannot replace the strong effects of dispersal. Thus, in a consumer-resource metapopulation with deterministic local extinction, the strength and spatial scale of consumer dispersal in relation to the spatial and temporal scales of the resource patch dynamics (patch destruction and regeneration, number, size and distance of patches) play a vital role for long-term persistence. The consequence for conservation management is that such metapopulations could in fact profit rather than suffer from decreasing connectivity of resource patches. 相似文献
7.
Torbjörn Nilsson 《Biological conservation》2004,115(2):227-239
Focusing on the wolf Canis lupus in Scandinavia as an example, criteria are proposed and an analysis performed to assess the effect on extinction risk of various control policies, while accounting simultaneously for effects of inbreeding depression and potential catastrophic events. Each control policy is characterized by a hunting pressure (the increase caused by hunting of annual mortality rates) combined with a hunting threshold (the population size below which hunting is not permitted). Catastrophes are taken into account by including the persistence of a severe catastrophe in the criterion for population viability. Based on these criteria, the results suggest that only a very limited amount of hunting should be permitted at low population sizes. The results also illustrate the importance of including a long-term perspective in modelling threatened populations. 相似文献
8.
David M. Wagner Lee C. Drickamer Christopher J. Allender Paul Keim 《Biological conservation》2006,130(3):331-339
Although the five species of prairie dogs (Cynomys spp.) are recognized as important components of grassland ecosystems in western North America, they have experienced major population declines due to poisoning, outbreaks of sylvatic plague, recreational shooting, and habitat conversion. From May 2000 to October 2001, we investigated 270 colonies of Gunnison’s prairie dog (Cynomys gunnisoni) in Arizona. Because these colonies were classified as active in previous surveys (1987, 1990-1994, 1998), we were able to examine their persistence. Most (70%) of the colonies became inactive between the initial and recent surveys, with colony extinctions spanning our study area. Colony persistence was positively associated with the persistence of the nearest neighboring colony but was not associated with major vegetation type, distance to nearest neighboring colony, or initial size of the colony. The amount of area occupied by individual colonies varied between surveys, sometimes dramatically. We found little evidence that the reduction in active colonies was due to poisoning, recreational shooting, or habitat conversion. Rather, direct and indirect evidence suggest plague is the primary factor negatively impacting Gunnison’s prairie dog populations in Arizona. Currently, there is no way to control or prevent plague outbreaks in Gunnison’s prairie dog populations. To mitigate the effects of localized plague outbreaks on the overall population of this species, we suggest that Gunnison’s prairie dog be reintroduced to public lands throughout its historical range. 相似文献
9.
This study investigates the dynamics and viability of a marsh fritillary butterfly Euphydryas aurinia metapopulation in a Belgian successional landscape. Based on capture-mark-recapture and winter nest census data, we first estimated demography (survival and recruitment rates, population size, density dependence) and dispersal parameters (emigration rate, effect of patch connectivity on dispersal, mortality during dispersal). Then using RAMAS/GIS platform, we parameterised a population viability analysis (PVA) model with these parameters to simulate the future of this metapopulation under different scenarios.The metapopulation does not seem viable even if natural reforestation is controlled by adequate management. In its present state, the patch system is not able to sustain enough individuals: due to the large temporal fluctuations in demographic parameters, a carrying capacity far higher than currently would be necessary to limit extinction risk to 1%, suggesting the existence of an extinction debt for the species in Belgium. The situation of E. aurinia appears much worse compared to two other fritillary species threatened in Belgium, for which similar PVA are available. It is therefore urgent to increase the carrying capacity of the patch system. How and where it is achieved are of secondary importance for the gain in viability: improvement of habitat quality through restoration, or increase of habitat quantity via enlargement of existing patches and/or creation of new habitat in the matrix. A regime of management based on regular re-opening and maintenance of habitat patches may be the only guarantee of long-term persistence for this critically endangered species in Belgium. 相似文献
10.
A population viability analysis (PVA) was conducted to assess the minimum viable population (MVP) of the Atlantic Forest spiny rat Trinomys eliasi, a species threatened by habitat loss and restricted geographical distribution. Objectives were to suggest quasi-extinction thresholds, estimate minimum areas of suitable habitat (MASH) and MVPs, and compare results with the species’ current status. The computer package VORTEX was used. The model predicted sizes of 200 animals to achieve demographic stability, but buffering declines in genetic variability required populations of 2000 animals. Estimated MASHs were approximately 250 and 2500 ha for demographic and genetic stability, respectively. Mortality rate and mean litter size were the most sensitive parameters to changes in model assumptions. The protection of known populations and the search for extant populations are the first steps in conservation. T. eliasi's issue could help protecting the coastal shrubland ecosystem of Rio de Janeiro state. Observing IUCN's criteria for listing threatened species, it is suggested that T. eliasi should be ranked as vulnerable in red lists. 相似文献
11.
We studied the persistence of 281 towns of the black-tailed prairie dog (Cynomys ludovicianus) from surveys conducted in Oklahoma in 1966 and 1967 and again in 1988 and 1989. Town size during initial surveys tended to increase along a northwesterly gradient toward the panhandle of the State, and larger towns tended to occur in clusters while small towns occurred as isolates. Persistence of prairie dog towns from 1967 to 1989 increased significantly with town size and decreased with town isolation, with higher persistence for towns that occurred in landscapes with greater coverage of other towns. Comparisons to our studies of persistence of towns mapped in 1989 and resurveyed in 1997 [Journal of Mammalogy, 82 (2001) 937] indicate that the latter part of this pattern was reversed, with persistence highest for the most isolated towns. The reversal in persistence patterns may be attributed to an outbreak of plague (Yersinia pestis) during the early 1990s, favoring isolated towns. We recommend adaptive management and a mixed strategy for the development of prairie reserves which should include networks (clusters) of relatively large reserves, along with large but isolated reserves across the species’ native range. 相似文献
12.
Domestic dogs (Canis familiaris) arrived in Zimbabwe ca. 1000 years ago. Numbers of free-ranging dogs have reached unprecedented levels in communal lands (agro-pastoralist rural areas), and interact with large wild carnivores along boundaries with wildlife reserves as predators and prey. This study examined a population of 236 dogs in a 33-km2 section of Gokwe Communal Land (GCL) bordering the Sengwa Wildlife Research Area (SWRA) in north-western Zimbabwe in 1995-1996. Dogs were found up to 6 km within the SWRA, and were the most common carnivore on the GCL-SWRA boundary. Observations of 16 radio-collared dogs showed that they were inefficient predators. Only 20 kills were recorded amongst the remaining dog population, of which three were wild ungulates. Dogs were unsuccessful predators due to their small group size (mean 1.7) and body mass (mean 14.7 kg), and the abundance of alternative food. It is therefore unlikely that they compete with large carnivores for wild prey. However, leopards (Panthera pardus), lions (P. leo) and spotted hyaenas (Crocuta crocuta) preyed on dogs in GCL, removing ?6% of the dog population in 1993. Such predation provides ideal circumstances for disease transmission. Canid disease was prevalent in the study area; including rabies and probably distemper. The risk of infection is greatest during the dry season (May-October), when peaks in rates of disease, carnivore incursions into GCL, and predation on dogs coincided. The role of jackals (Canis adustus and Canis mesomelas) and spotted hyaena predation of dogs is discussed in relation to disease epidemics within wildlife reserves. With a dog population growth rate of 6.5% per annum, and the prevalence of canid diseases, the conservation threat posed by dogs is escalating on communal land-wildlife reserve boundaries in Zimbabwe. Measures to control dog numbers and improve vaccination coverage of dogs are discussed. 相似文献
13.
Olusegun O. Osunkoya 《Biological conservation》2003,114(1):39-51
Gardenia actinocarpa (Rubiaceae)—an endemic and dioecious shrub-small tree of the lowland rainforest of Cape Tribulation, NE Australia—is evaluated for its long-term population persistence using five-year demographic data from three permanent plots of the species. Two-sex, size-specific Lefkovitch matrices were constructed to evaluate the species’ vital rates and extinction thresholds. One site indicated a sign of significant population growth (annual λ=1.056), while the remaining two gave λs close to unity (λ=1.0102 and 1.007). Overall, λ was greater than 1 (λ=1.0281) indicating that G. actinocarpa will increase in population size with time, though male plants were projected to grow faster in number than female plants. Elasticity analyses indicated that the largest size class (>22 cm diameter) made the greatest contribution to population growth (28%), especially the male plants (23%). Also λ was equally sensitive to survival/stasis (45%) and growth (44%) and least sensitive to fecundity (11%). Stochastic simulations gave 0.505 probability of quasi-extinction to 10% of its initial size in 100 years of population growth projection- suggesting that the endemic G. actinocarpa, despite a positive rate of population increase, is indeed threatened. Sensitivity analyses and numerical simulations showed that to maintain population persistence of G. actinocarpa, efforts should concentrate, following cost-benefit analyses, on increasing seed production coupled with enhancing establishment of individuals in the seedling, juvenile and vegetative phases. 相似文献
14.
S. Roques C. Díaz-Paniagua A. Portheault N. Pérez-Santigosa J. Hidalgo-Vila 《Biological conservation》2006,129(2):236-243
The freshwater pond turtle, Emys orbicularis, has recently suffered from population declines throughout its range, mainly due to habitat destruction. The mating strategies of this species were studied using genetic data from successive clutches within and between years. To test for the occurrence and frequency of multiple paternity and sperm storage, genetic paternity at six microsatellite markers was assessed in 114 embryos and hatchlings from single and subsequent clutches of 11 females (including clutches from the same or consecutive years). Multiple paternity was rare and only found in two out of 20 clutches from 11 females. All annual successive clutches and 58% of the clutches in the next year, were fertilized with sperm from the same male. The use of stored sperm is thus a frequent strategy in E. orbicularis. However, hatching rate, hatchling mass, and hatchling length decreased in clutches fertilized by stored sperm, suggesting sperm depletion or deterioration through time. The occurrence of stored sperm despite an associated reduced reproductive output indicated that mating and/or the fertilization process is costly to females. The low incidence of multiple paternity may simply be the residual consequence of the capacity to store viable sperm. These results provide important and innovative insights for the conservation of E. orbicularis. In threatened populations, management strategies may aim to enhance effective copulations in order to increase the reproductive output of females. 相似文献
15.
Chris Lalas 《Biological conservation》2003,114(1):67-78
Management plans for threatened or recovering large vertebrate species that are increasing in population size and range focus on the establishment of viable populations within set temporal limits. New Zealand (Hookers) sea lions (Phocarctos hookeri) were declared a threatened species in 1997, and New Zealand legislation requires that threatened species of marine mammals must be managed to reduce human-induced mortality and achieve a non-threatened status within 20 years. The present breeding distribution of P. hookeri is highly localised, with over 95% of total annual pup production located at Auckland Islands and almost all of the remainder at Campbell Island. Breeding elsewhere has been ephemeral or restricted to <10 adult females. The only recorded sustainable breeding at a new location has been at Otago, South Island, New Zealand. This breeding population consisted of a total of four breeding females in 2002 and is derived from one immigrant female that gave birth to her first pup in the 1993/1994 breeding season. The New Zealand Department of Conservation management plan specifies that to achieve a non-threatened status P. hookeri (1) at Otago must increase in the number of breeding females to ?10, and (2) must establish ?two new breeding locations within the 20-year time frame, each with ?10 breeding females. This study 1) projects the population growth trends at a new location (Otago) to see if it will achieve ?10 breeding females within the legislated time frame, and (2) examines the likelihood that other breeding locations will establish elsewhere given the demographic information available for this species. We present 20 deterministic and three stochastic Leslie matrix model scenarios for female population growth for the initial years following the start of breeding at a new location. Our results indicate that (1) a new breeding population derived from one immigrant female is unlikely to reach 10 breeding females in 20 years; this duration is more likely to be 23-41 years (deterministic models) or 23-26 years (stochastic model), (2) the likelihood of two new sites establishing within 20 years is unquantifiable, but the probability is low, and (3) if the legislated outcome and time limit are not revised in the population management plan, the feasibility and effectiveness of re-locating young females could be investigated. 相似文献
16.
Peter G. Spooner 《Biological conservation》2005,122(2):231-242
Disturbances from road management activities are often considered to be a major threat to plants in roadside environments, however effects may not be deleterious to all plants. The post-disturbance response of three Acacia species with different life-history attributes was compared in four road reserves impacted by soil disturbance from grading activities. Recovery of acacias to grading was variable, however basal resprouting, root suckering and seedling emergence led to a 6.2% population increase for all road reserves combined. In two road reserves, there was significant resprouting of the facultative seeder A. decora, and 2 years after disturbance, resprouts reached mean heights of 71 and 74 cm. One year after disturbance, 71% of A. decora resprouts flowered and 49% also set viable seed, and there was a significant positive relationship between flowers produced and viable seed set. Similarly, 65% of resprouts of the facultative seeder A. montana flowered but only 10% set viable seed. In contrast, there was patchy seedling emergence of the obligate seeder A. pycnantha and to a lesser extent A. montana, and seedlings did not reach reproductive maturity 1 year after disturbance. Drought most likely reduced seedling numbers, as seedlings were only recorded in shaded road reserves, where additional water was applied from roadworks activities. Grading of roadside environments appears to favour plants with strong resprouting ability, and persistence of Acacia populations will depend on the timing of soil disturbances from grading activities in relation to species life-history attributes. 相似文献
17.
This study presented evidence that creates a quandary for conservation management: predation by one threatened species, New Zealand sea lion (Phocarctos hookeri), threatens the viability of another threatened species, yellow-eyed penguin (Megadyptes antipodes), at Otago Peninsula, South Island, New Zealand. Otago Peninsula holds the largest population of yellow-eyed penguins on South Island and the only breeding population of New Zealand sea lions on the New Zealand mainland. New Zealand sea lions here represent the vanguard of re-colonisation within their prehistoric range, with nine females and 50-70 males resident in 2005. The initial indication of a potential problem was an attack on a yellow-eyed penguin by a New Zealand sea lion witnessed in 1996. The majority of 20 records for attacks were at two neighbouring sites, where they coincided with decreases in penguin nest numbers and adult annual survival. In contrast, penguin nest numbers increased at a third site, the main base for male sea lions at Otago Peninsula. Evidence from prey remains indicated that male sea lions did not eat yellow-eyed penguins but that females ate 20-30 annually, with one individual possibly responsible for most kills. Modelling indicated that the penguin population at any one site could not remain viable if it was the sole source of penguins killed. The dilemma is either to do nothing, and risk collapse of the Otago Peninsula population of yellow-eyed penguins, or to take action against known culprits, and risk failure in re-colonisation of the New Zealand mainland by New Zealand sea lions. 相似文献
18.
Although demographic models have become increasingly important tools in plant conservation, few models have considered the implications of seed banks for population persistence. Based on a 15-year study of the threatened herb, Helenium virginicum, we created a stage-class transition matrix to model the population dynamics of the plant. Our goal was to determine the role of the seed bank in population persistence and in the design of monitoring programs for the plant. Using data from marked plants, a long-term study of seed viability, and a seed bank census, we created a deterministic model and three stochastic models. The stochastic models were a model in which yearly correlations among parameters were retained, a model in which parameters were uncorrelated, and a model in which parameters were derived from log-normal distribution. We also constructed a fourth model in which we assumed a minimum seed lifetime consistent with the seed viability data. Both elasticity and perturbation analysis suggested that seed survival within the seed bank had by far the largest effects on the population growth rate (λ), with 47-64% of the change in λ being controlled by seed survival. Correlations among life history parameters had little effect on λ in the original models, but substantially reduced λ (from 0.97 to 0.86) when seed survival was limited. Given the importance of the seed bank and the high yearly variability in adult plant density, we used simulations to compare power to detect declines with seed bank samples versus censuses of adult plants. The power of adult plant censuses was extremely low (13-22%). The power of seed bank censuses was substantially higher (48-59%), but was limited by large pulses of recruitment to the seed bank in good years. Power was only moderately reduced when seeds were sampled every two or four years instead of yearly (from 59% to 48%). Together, our results suggest that seed survival is crucial to persistence of Helenium populations and that future empirical studies should focus on understanding the factors that affect seed survival. In addition, managers should consider seed bank censuses rather than above-ground plants when designing monitoring programs for plants in variable environments where above-ground plants vary greatly from year to year. 相似文献
19.
Larissa Rosa de Oliveira Milena Arias-Schreiber João S. Morgante 《Biological conservation》2006,131(4):505-509
The census population size (N) is usually the only information available for most threatened species. For evolutionary matters, the effective population size (Ne), not the census number, is a prime concern. Factors such as variation in the sex ratio of breeding individuals, variation of population size in different generations and mating system are important. The South American fur seal, Arctocephalus australis, has been exploited in Peru by humans since ca. 2000 BC and now the original population declined 72%, as a result of low food availability during the severe El Niño in 1997-1998. In this sense A. australis is now classified as in danger of extinction in Peru. We present the first estimate of Ne of the Peruvian population of A. australis that takes into account the effects of mating system and variation in population size caused by the 1997-1998 El Niño. The resulting Ne was 2153 specimens. We believe that the estimated Ne for the Peruvian population is a critical value, because it is significantly lower than the mean minimum viable population for vertebrates (7000 breeding age adults). This estimated Ne is of critical importance because combined with the current El Niño events are reasons of great concern for the survival of the species and should be taken into account in future management plans to ensure the conservation and protection of the species in the Peruvian coast. 相似文献
20.
Jiancheng Song Joanna Murdoch Andrew Young John Clemens 《Biological conservation》2008,141(8):2041-2053
Clianthus is an acutely threatened, bird-pollinated genus endemic to New Zealand, represented in the wild by only one population of C. puniceus and 11 populations of C. maximus, each with very few individuals (typically <10 per population). A limited number of named Clianthus cultivars of indeterminate origin are commonly grown as ornamentals. Genomic DNA from individual Clianthus plants was extracted for genetic diversity analysis using a range of molecular markers, including amplified fragment length polymorphism (AFLP). Data were analysed by the unweighted pair-group method with arithmetic averaging (UPGMA), the generation of Neighbor-Joining trees, and analyses of molecular variance (AMOVA). Genetic distance between wild populations of C. maximus was highly correlated with geographical distance between populations. Sequencing of intron 2 of a putative partial homologue of the floral meristem identity gene LEAFY (CmLFY) revealed a 7 bp deletion that was exhibited homozygously in the more northern populations of C. maximus, and in all individuals tested from the sole population of C. puniceus. This deletion was not exhibited in more southern populations of C. maximus. Further, one geographically intermediate population contained some plants that were heterozygous for the deletion. Parallel analyses of cultivated Clianthus genotypes, more than half of which were also homozygous for the 7 bp deletion, showed that these were not representative of the broad, but threatened, diversity remaining in the wild. It is argued that wild populations of C. maximus are unlikely to have arisen from the escape of plants from cultivation. Conservation effort should focus on the protection and study of the extant plants in these wild populations, rather than on the introduction of disturbance regimes to uncover potential seed banks. 相似文献