Elasticity analysis as an important tool in evolutionary and population ecology

Elasticity analysis estimates the proportional change in the population growth rate for a proportional change in a vital rate (i.e. survival, growth or reproduction). It can be used to pinpoint those parts of an organism’s life history that should be the focus of management effort, or those that contribute most to fitness. Recent theoretical work has emphasized some limitations of the technique, has overcome other problems, and has shown that it is robust to some violations of its underlying assumptions. Thus, although care is needed, elasticity analysis is a simple first step in answering important questions in evolutionary and population ecology.     

Effect of reproductive modes and environmental heterogeneity in the population dynamics of a geographically widespread clonal desert cactus

The dynamics of plant populations in arid environments are largely affected by the unpredictable environmental conditions and are fine-tuned by biotic factors, such as modes of recruitment. A single species must cope with both spatial and temporal heterogeneity that trigger pulses of sexual and clonal establishment throughout its distributional range. We studied two populations of the clonal, purple prickly pear cactus, Opuntia macrocentra, in order to contrast the factors responsible for the population dynamics of a common, widely distributed species. The study sites were located in protected areas that correspond to extreme latitudinal locations for this species within the Chihuahuan Desert. We studied both populations for four consecutive years and determined the demographic consequences of environmental variability and the mode of reproduction using matrix population models, life table response experiments (LTREs), and loop and perturbation analyses. Although both populations seemed fairly stable (population growth rate, λ∼1), different demographic parameters and different life cycle routes were responsible for this stability in each population. In the southernmost population (MBR) LTRE and loop and elasticity analyses showed that stasis is the demographic process with the highest contributions to λ, followed by sexual reproduction, and clonal propagation contributed the least. The northern population (CR) had both higher elasticities and larger contributions of stasis, followed by clonal propagation and sexual recruitment. Loop analysis also showed that individuals in CR have more paths to complete a life cycle than those in MBR. As a consequence, each population differed in life history traits (e.g., size class structure, size at sexual maturity, and reproductive value). Numerical perturbation analyses showed a small effect of the seed bank on the λ of both populations, while the transition from seeds to seedlings had an important effect mainly in the northern population. Clonal propagation (higher survival and higher contributions to vital rates) seems to be more important for maintaining populations over long time periods than sexual reproduction.     

A simulation model of the Devils Hole pupfish population using monthly length-frequency distributions

The Devils Hole pupfish, Cyprinodon diabolis, is a federally-endangered fish that is endemic to Devils Hole, a discontiguous part of Death Valley National Park in Nye County, Nevada. Due to its status, Devils Hole pupfish monitoring must be non-obtrusive and thereby exclude techniques that require handling fish. Due to a recent decline in pupfish abundance, Devils Hole pupfish managers have expressed a need for a model that describes population dynamics. This population model would be used to identify vulnerable life history stage(s) and inform management actions. We constructed a set of individual-based simulation models designed to explore effects of population processes and evaluate assumptions. We developed a baseline model, whose output best resembled both observed length-frequency data and predicted intra-annual abundance patterns. We then ran simulations with 5 % increases in egg-larval, juvenile, and adult survival rates to better understand Devils Hole pupfish life history, thereby helping identify vulnerable life history stages that should become the target of management actions. Simulation models with temporally constant adult, juvenile, and egg-larval survival rates were able to reproduce observed length-frequency distributions and predicted intra-annual population patterns. In particular, models with monthly adult and juvenile survival rates of 80 % and an egg-larval survival rate of 4.7 % replicated patterns in observed data. Population growth was most affected by 5 % increases in egg-larval survival, whereas adult and juvenile survival rates had similar but lesser effects on population growth. Outputs from the model were used to assess factors suspected of influencing Devils Hole pupfish population decline.     

Conservation prospects for threatened Vietnamese tree species: results from a demographic study

Given that changes in population size are slow, information on future prospects of long-lived tree species is necessarily obtained from demographic models. We studied six threatened tree species in four Vietnamese protected areas: the broad-leaved Annamocarya sinensis, Manglietia fordiana and Parashorea chinensis, and the coniferous Calocedrus macrolepis, Dacrydium elatum and Pinus kwangtungensis. With data from a 2-year field study on recruitment, growth and survival, we constructed matrix models for each species. All species showed continuous regeneration, as indicated by annual seedling recruitment and inverse J-shaped population structures. To evaluate the future prospects of our study species, we calculated three parameters: (1) asymptotic growth rates (λ) from matrix models indicated significant population declines of 2–3%/year for two species; (2) population trajectories for 50–100 years showed slight population declines (0–3%/year) for five species; and (3) the reproductive period required for an adult tree to replace itself was excessive for three of the six species, suggesting that these species presently have insufficient recruitment. Overall agreement of the three parameters was low, showing that reliance on just one parameter is risky. Combining the three parameters we concluded that prospects are good for Dacrydium and Parashorea, worrisome for Annamocarya, Manglietia and Pinus, and intermediate for Calocedrus. We argue that conservation should involve strict protection of (pre-)adult trees, as their survival is crucial for population maintenance in all species (high elasticity). For species with poor demographic prospects, active intervention is required to improve seedling and tree growth, enrich populations with seedlings from controlled germination, and restore habitat. Finally, our study suggests that these conservation measures apply to long-lived trees in general, given that their demography is highly similar. Such measures should be taken before populations decline below critical levels, as long-lived species will respond slowly to management. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Inferring population and metapopulation dynamics of Liparis loeselii from single-census and inventory data

To conserve endangered species, information is needed on (meta)population responses to habitat quality and management. As possibilities for long-term studies are generally limited, it is important to obtain as much information as possible in a single field season.We obtained such single-census data for the orchid Liparis loeselii, a European Habitat Directive species. Stage structures of 15 Dutch dune and fen populations were related to vegetation structure, environmental indicators, and management. Botanical inventory records from 1930 to 2003 were used to infer population life spans.Cluster analysis did not reveal successional stage structure types. Dense populations with high recruitment mainly occurred in open, young-successional vegetation with high soil pH. High soil humidity and acidification negatively affected orchid densities. Early mowing was preferable over late mowing in dune slacks, because the latter reduced juvenile densities. The predominant population life span was three to eight years, and similar for dune slacks and fens. Longer life spans were occasionally observed at mown sites with influx of base-rich water.Our results suggest high metapopulation dynamics. Long-term metapopulation viability requires the formation of new habitat by dune slack formation in dunes and peat removal in fens. Population persistence can be prolonged to some extent by mowing, extensive grazing, or sod removal if natural habitat formation is impossible. Our study demonstrates that useful information on (meta)population ecology and viability can be obtained in a single field season.     

Land use heterogeneity causes variation in demographic viability of a bioindicator of species-richness in protected fen grasslands

Land use change is one of the main drivers of species extinction. In Europe, grasslands are under active conflict between conservation efforts and increasing agricultural pressures. Here, we examine the demographic effects of differential land use on the herbaceous perennial Trollius europaeus L. (Ranunculaceae), a bioindicator of species-richness and ecosystem services in wet grasslands of Central Europe. Demographic data were collected in 2006–2009 from nine populations in seven protected sites of northeastern Germany representing four land use types. We constructed stage-based matrix population models to explore the effects of various land management on demographic viability of focal populations. We show that most studied populations are declining (λ < 1), although the estimates of local extinction vary between ≤15 years for grazed and woodland populations, and 20–99 years for mown and abandoned populations. The joint information from our elasticity analyses and life table response experiments revealed that reproduction, growth of small vegetative individuals and survival of reproductive stages are most important for population viability. Our study shows that the current land uses in protected areas where T. europaeus is found is incompatible with its long-term viability. We suggest that, when compatible with in situ practices, grasslands containing this species be mown after maturity in order to enhance seedling recruitment and to reduce competition for juveniles. Prolonged extinction times in abandoned populations offer a buffer to develop conservation schemes there. An improvement of conservation measures is urgently needed to maintain the populations of this important bioindicator and its associated community of moist species-rich fen grasslands.     

Dynamics of isolated <Emphasis Type="Italic">Saponaria bellidifolia</Emphasis> Sm. populations at northern range periphery

Four populations of Saponaria bellidifolia situated at the species’ northern range periphery (Apuseni Mountains, southeastern Carpathians) were monitored over a period of 5 years. They were chosen to represent different habitat types (rocky, fixed screes, open screes and grassy), disturbance regime (fire), and population sizes (categorized as large and small). The reproductive effort was quantified, and matrix models were used to describe the population dynamics and to assess population viability. Saponaria bellidifolia had very stable population dynamics in the harsh and stable abiotic conditions of the outcrops where populations occur. Habitat conditions exerted a notable influence on the species’ population reproductive performance, growth rate, and vital rates, whereas population size and climate did not have a clear-cut effect on the dynamics of the species. Saponaria bellidifolia maintains viable populations in the southeastern Carpathians, at its northern range periphery.     

Asynchronization of local population dynamics and persistence of a metapopulation: a lesson from an endangered composite plant, Aster kantoensis

Fragmentation of a large habitat makes local populations less linked to others, and a whole population structure changes to a metapopulation. The smaller a local population is, the more strengthened extinction factors become. Then, frequent extinctions of local populations threaten persistence of the metapopulation unless recolonizations occur rapidly enough after local extinctions. Spatially structured models have been more widely used for predicting future population dynamics and for assessing the extinction risk of a metapopulation. In this article, we first review such spatially structured models that have been applied to conservation biology, focusing on effects of asynchronization among local population dynamics on persistence of the whole metapopulation. Second, we introduce our ongoing project on extinction risk assessment of an endangered composite biennial plant, Aster kantoensis, in the riverside habitat, based on a lattice model for describing its spatiotemporal population dynamics. The model predicted that the extinction risk of A. kantoensis depends on both the frequency of flood occurrence and the time to coverage of a local habitat by other competitively stronger perennials. Finally, we present a measure (Hassell and Pacala's CV ²) for quantifying the effect of asynchronization among local population dynamics on the persistence of a whole metapopulation in conservation ecology. Received: January 12, 2000 / Accepted: February 8, 2000     

Genetic diversity of two endemic and endangered Plantago species

Plantago algarbiensis and Plantago almogravensis are two endangered and endemic species from Portugal. Due to the rarity and endangered nature of these species as well as the lack of molecular data, their genetic variation was evaluated using ISSR and RAPD markers. P. algarbiensis species showed higher genetic variability (73.9% of polymorphism) than P. almogravensis (61.2%). The two species revealed a high level of genetic diversity, with a Nei's genetic diversity of 0.1965 and 0.2309 and a Shannon's diversity index of 0.2975 and 0.3520, for P. almogravensis and P. algarbiensis, respectively. A low level of genetic differentiation was observed (Gst = 0.1873) among the species. However, the cluster and PCA analyses, based on genetic similarity, revealed two main, clearly separate clusters, which directly corresponded to the plants isolated from each species. In situ and ex situ measures should be applied in order to preserve both species but, based on these results, P. almogravensis population should be a priority for conservation.     

The cost of stabilising the German lapwing population: A bioeconomic study on lapwing population development and distribution using a cellular automaton

The populations of farmland birds such as the lapwing (Vanellus vanellus) are declining sharply. These populations suffer from frequent cultivation measures and degraded habitat quality on arable land. An effective conservation measure is the lapwing plot, an agriculturally unused section within an arable field. We address German lapwing population development and dispersal if different shares of the population are safeguarded by the use of lapwing plots. We adapted a matrix projection model and extended it by projecting population development in three different habitat types (arable land, grassland and optimal habitat) and in varying scenarios. We introduced a cellular automaton and developed a new algorithm to simulate dispersal dynamics. The results show that without further conservation measures, the population could decline from 70 000 breeding pairs in 2006 to 12 000 or 23 000 pairs in 2055, depending on the underlying assumptions. Our model can be used to set environmental goals and then simulate the necessary implementation levels of conservation measures, such as the lapwing plot, and estimate the corresponding costs. For the goal of at least stabilising the population, 60% of the pairs in the normal agricultural landscape need to be safeguarded. For the population on arable land the corresponding costs range between 1.6 and 2.8 million € per year.     

Demography of the demosponge Amphimedon compressa: Evaluation of the importance of sexual versus asexual recruitment to its population dynamics

We used size-based population matrix models to describe the demography of the demosponge Amphimedon compressa. The relative importance of growth, survivorship, and recruitment to population growth (λ) was assessed by performing elasticity and life table response experiment (LTRE) analyses. We also evaluated the relative contribution of sexual and asexual recruitment to λ by analyzing four different scenarios: (1) the combined impact of sexual and asexual recruitment, (2) the impact of only sexual recruits, (3) the impact of only asexual fragmentation, and (4) the impact of no recruitment. Size-based transition matrices were parameterized with field data collected at two sites in the southwest coast of Puerto Rico: Media Luna West (MLW), a reef exposed to high water movement and at Las Pelotas (LP), a reef experiencing low water motion. Estimated λ of 0.8940 and 0.7973 at MLW and LP respectively suggest that both populations are declining. Elasticity analysis indicated that survivorship may be the most important contributor to λ at both sites. However, λ at MLW was influenced more by the survivorship of small individuals whereas survivorship of the large size-class contributed the most to λ at LP. LTRE analysis indicates that the difference in λ between sites was mostly due to difference in survivorship of small sponges. At both sites, λ decreased considerably when sexual recruitment was excluded from the model whereas the absence of asexual recruitment barely changed λ. Therefore, it is suggested that sexual recruitment plays a major role (in comparison to asexual fragmentation) in the population dynamics of this sponge at the studied sites. We conclude that spatial variability in water motion plays an important role in population dynamics of A. compressa by influencing survivorship patterns, including the relative contribution of asexual and sexual recruitment to population growth.     

The impact of early Quaternary climate change on the diversification and population dynamics of a South American cactus species

Aim

Climatic oscillations have been suggested to promote speciation and changes in species distributions, mostly in connection with the Last Glacial Maximum (LGM). However, the LGM is just the most recent of the 20+ glacial‐interglacial periods that characterise the Quaternary. Here, we investigate the role of climatic changes and geomorphological features in shaping the evolution, distribution and population dynamics of the South American cactus Cereus hildmannianus.

Location

South‐eastern South America.

Methods

We built a large fossil‐calibrated phylogeny for cacti (family Cactaceae), comprising 128 species distributed in all subfamilies, using a Bayesian relaxed clock. We used the results to derive a secondary calibration for a population‐level phylogeny in C. hildmannianus. We amplified two plastid (trnQ‐5′rps16 and psbJ‐petA) and one nuclear marker (PhyC) for 24 populations. We estimated population dynamics, ancestral areas, and species distribution models to infer the clade's evolutionary history in time and space.

Results

Our results show a major population divergence of C. hildmannianus at c. 2.60 Ma, which is strikingly coincident with the transition of the Pliocene–Pleistocene and onset of Quaternary glaciations. This was followed by a complex phylogeographic scenario involving population expansions across ecologically diverse regions.

Main conclusions

Contrary to the dominant research focus on the LGM, our study indicates a major impact of the first Quaternary glaciation on the distribution and population divergence of a South American plant species. Further intraspecific events seem related to successive climatic changes and geomorphology, including the development of the coastal plain and its peculiar diversity. We propose that the first Quaternary glaciation acted as a major evolutionary bottleneck, whereby many warm‐adapted lineages succumbed, while those that survived could diversify and better cope with subsequent climatic oscillations.     

Growth and demography of a declining,endangered cactus in the Sonoran Desert

Increases in the incidence and severity of drought threaten the viability of rare plants in arid regions. The endangered Nichol's Turk's head cactus (Echinocactus horizonthalonius Lemaire var. nicholii L. Benson) occurs only in four small, isolated populations in the Sonoran Desert of North America. Since 1995 we have monitored a population in southeastern Arizona (USA). Here we report 23 years of observations on abundance, growth, mortality, flowering and recruitment. Abundance of plants decreased from 132 in 1996 to 40 in 2017, with 100 individuals recruited and 203 dying during the study. Individual plants grew slowly, increasing annually by an average of 0.22 cm (95% confidence interval, 0.18–0.26 cm) in diameter and 0.27 cm (0.20–0.33 cm) in height. Growth was slowest when drought was most severe and slowed as plants reached maximum size. Annual mortality increased markedly across the study period and did not vary with plant size. Annual probability of flowering increased as plants increased in diameter but not in height, and varied with precipitation and drought but not with mean annual temperature. Recruitment was higher when average temperature was higher and the number of recruits per capita increased across the study period. The annual rate of change in abundance averaged −6%, but shifted markedly from −1% during 1995–2008 to −11% during 2008–2017. Our results indicate that the population's decline was not a consequence of failed recruitment but of increased mortality, which we discuss in the context of climate and herbivory.     

Extinction threats of a narrowly endemic shrub, Stachyurus macrocarpus (Stachyuraceae) in the Ogasawara Islands

Stachyurus macrocarpus is a narrowly endemic endangered shrub of which only one population remains on Chichi-jima Island (Ogasawara). We surveyed its population dynamics and reproductive states for 4 years and analyzed the population viability. In a survey of its entire distribution range, a total of 87 S. macrocarpus individuals have been found and 68 individuals have been confirmed in 2007. Thus, the actual population size is estimated to be less than 100 individuals. Environmental conditions and the results of a hand-pollination experiment suggest that low fruit setting in both sexes (female: 4.9–11.2%; hermaphrodite: 0.0%) may be caused by resource limitation. In addition, fruit predation by alien Rattus rattus was observed despite the rare fruit setting. The small effective population size (23.1–24.6 individuals) and hermaphrodite-biased sex ratio (46 hermaphrodites:12 females) would increase the risk of extinction. The habitat of S. macrocarpus was limited to dense scrubland and forest understory, and seedling regeneration was very scarce. During the survey period, 19 individuals (21.8%) were found dead, there were only two seedling recruitments, and the annual population growth rate was 0.979. The lack of occurrence on the south and west slopes and the shortness of shrubs in open spaces suggests that S. macrocarpus suffers stress from both dryness and frequent typhoons. However, S. macrocarpus also exhibited high mortality of shoot in forest understories. These findings suggest that the suitable habitat of S. macrocarpus is likely to be narrow in Ogasawara. While the recent increase of goat grazing has not affected individual mortality, 58.6% of shoots that had been grazed by goats were dead within 2 years. As elasticity analysis had shown that larger individuals make a greater contribution to the population growth rate, repeated goat grazing would impact the S. macrocarpus population in the near future by decreasing the vitality of larger individuals. Emergency measures for protecting the shrub from goat grazing and reinforcing the population through nursery cultivation were proposed.     

Sensitivity analysis of transient population dynamics

Short-term, transient population dynamics can differ in important ways from long-term asymptotic dynamics. Just as perturbation analysis (sensitivity and elasticity) of the asymptotic growth rate reveals the effects of the vital rates on long-term growth, the perturbation analysis of transient dynamics can reveal the determinants of short-term patterns. In this article, I present a completely new approach to transient sensitivity and elasticity analysis, using methods from matrix calculus. Unlike previous methods, this approach applies not only to linear time-invariant models but also to time-varying, subsidized, stochastic, nonlinear and spatial models. It is computationally simple, and does not require calculation of eigenvalues or eigenvectors. The method is presented along with applications to plant and animal populations.     

种群生存力分析研究进展和趋势

种群生存力分析（PVA）是正在迅速发展的新方法,已成为保护生物学研究的热点。它主要研究随机干扰对小种群绝灭的影响,其目的是制定最小可存活种群（MVP）,把绝灭减少到可接受的水平。随机干扰可分四类;统计随机性,环境随机性,自然灾害和遗传随机性。确定MVP的方法有三种：理论模型,模拟模型,模拟模型和岛屿生物地理学方法。理论模型主要研究理想或特定条件下随机因素对种群的影响;模拟模型是利用计算机模拟种群绝灭过程;岛屿生物地理学方法主要分析岛屿物种的分布和存活,证实分析模型和模拟模型。已有大量的文献研究统计随机性,环境随机性和自然灾害的行为特征,但遗传因素与种群生存力之间的关系还不清楚。建立包括四种随机性的综合性模型,广泛地检验PVA模型,系统地研制目标种的遗传和生态特性以及MVP的实际应用是PVA的发展趋势。     

The fast–slow continuum and mammalian life-history patterns: an empirical evaluation

The fast–slow continuum hypothesis has been proposed to explain the diversity of life-history patterns exhibited by biological populations, but the quantification and population-dynamic consequences of the continuum has remained unclear. I used the ratio of fertility rate to age at first reproduction (F/α ratio) to quantify the tempo of life-history of 138 populations of mammals, and investigated the life-history and population-dynamic consequences of being “fast” or “slow”. “Fast” mammals (F/α>0.60) were characterized by early maturity, short lifespans, low survival rates, and high fertility and projected population growth rate (λ) compared to “slow” (F/α<0.15) mammals. In “fast” populations, λ was overwhelmingly most sensitive to changes in reproductive parameters (age at first reproduction and fertility rates) and relatively insensitive to changes in survival rates. In “slow” populations, λ was very sensitive to changes in juvenile or adult survival rates, and relatively insensitive to changes in reproductive parameters. The pattern of relationships between the F/α ratio and life-history variables, λ, and elasticity of λ to changes in life-history variables persisted even after the effects of body size and phylogeny were statistically removed. These results suggest that fast–slow continuum in mammalian life-history is independent of body size or phylogeny, that the F/α ratio adequately quantifies the position of a population along a fast–slow continuum, and that the tempo of life- histories has substantial population-dynamic consequences.

Zusammenfassung

Die r-K-Kontinuum-Hypothese wurde aufgestellt, um die Diversität von ,,life-history“-Mustern biologischer Populationen zu erklären, aber die Quantifizierung und die Kosnsequenzen für die Populationsdynamik des Kontinuums blieben unklar. Ich benutze das verhältnis der Fortpflanzungsrate zum Fortpflanzungsalter (F/α-Verhältnis) um die Geschwindigkeit der ,,life-history“ von 138 Populationen von Säugetieren zu quantifizieren und untersuchte die Konsequenzen fur die Lebensweise sowie die Populationsdynamik des,,schnell“oder,,langsam “-Seins. ,,Schnelle“Säugetiere (F/α>0.60) waren durch eine frühe Reife, kurze Lebenszeiten, geringe Überlebensraten sowie durch eine große Fertilität und hochgerechnete Populationswachstumsrate (λ) im Vergleich zu ,,langsamen“(F/α<0.15) Säugetieren charakterisiert. In ,,schnellen“ Population reagierte (λ) überwältigend sensibel auf Änderungen in den Fortpflanzungsparametern (Fortpflanzunsalter und Fertilitätsrate) und relativ gering auf Veräanderungen in der Überlebensrate. In ,,langsamen“ Populationen reagierte (λ) sehr sensibel auf Veräanderungen in den reproduktiven Parametern. Das Muster der Beziehung zwischen dem (F/α-Verhältnis) und den Variablen der ,,life-history“,λ, und die Elastizität von λ gegenüber Veränderungen in den variablen der Lebensweise bliev sogar bestehen, nachdem die Effekte von Körpergröße und Phylogenese statistisch eliminiert wurden. Diese Ergebnisse lassen vermuten, dass das r-K-Kontinuum in der ,,life-history“der Säugetiere unabhängig von der Körpergröße und Phylogenie ist, dass das F/α-Verhältnis die Position einer Population im r-K-Kontinuum quantifiziert und dass die Geschwindigkeit der,,life-history“beachtliche konsequenzen fur die Populationsdynamik hat.     

Viability and Management of an Endangered Capercaillie (Tetrao urogallus) Metapopulation in the Jura Mountains, Western Switzerland

The populations of Capercaillie (Tetrao urogallus), the largest European grouse, have seriously declined during the last century over most of their distribution in western and central Europe. In the Jura mountains, the relict population is now isolated and critically endangered (about 500 breeding adults). We developed a simulation software (TetrasPool) that accounts for age and spatial structure as well as stochastic processes, to perform a viability analysis and explore management scenarios for this population, capitalizing on a 24 years-long series of field data. Simulations predict a marked decline and a significant extinction risk over the next century, largely due to environmental and demographic stochasticity (average values of life-history parameters would otherwise allow stability). Variances among scenarios mainly stem from uncertainties about the shape and intensity of density dependence. Uncertainty analyses suggest to focus conservation efforts on enhancing, not only adult survival (as often advocated for long-lived species), but also recruitment. The juvenile stage matters when local populations undergo extinctions, because it ensures connectivity and recolonization. Besides limiting human perturbations, a silvicultural strategy aimed at opening forest structure should improve the quality and surface of available patches, independent of their size and localization. Such measures are to be taken urgently, if the population is to be saved.     

Micropropagation of <Emphasis Type="Italic">Drosophyllum lusitanicum</Emphasis> (Dewy pine), an endangered West Mediterranean endemic insectivorous plant

In this work, in vitro clonal propagation of Drosophyllum lusitanicum (Dewy pine) was obtained from seedlings germinated in vitro. Seeds were collected in various populations identified in the Algarve region and germinated in vitro on MS medium supplemented with 0.5 mg l^–1 BA (6-benzyladenine) and 0.1 mg l^–1 GA₃ (gibberellic acid). The obtained shoots were used in several multiplication assays. The best results were observed in MS medium supplemented with 0.2 or 0.5 mg l^–1 zeatin. The highest rooting frequency (83%) was observed on 1/4MS medium supplemented with 0.2 mg l^–1 IBA (indole-3-butyric acid). Fifty percent of the plantlets were successfully acclimatized to ex vitro conditions, exhibiting normal development. Plans are underway to reintroduce the in vitro produced plants from this study in selected locations in their natural habitat.