Intermediate perennial-annual populations ofOryza perennis found in Thailand and their evolutionary significance

To reexamine the mode of variations in adaptive mechanisms in the Asian form ofOryza perennis, the breeding behavior of natural populations was observed at eight sites selected in Thailand. One population consisted of seedlings only (annual), and five consisted of ratooned plants only (perennial), while two others were mixtures of both. The annual population had a larger number of buried seeds at the habitat than had the others. In the habitat of the annual population, annual species were predominant, while perennial populations tended to coexist with perennial species. The annual population was in a temporary swamp, while perennial populations were found at sites more deeply inundated in the rainy season and retaining moisture in the dry season. This indicated the role of water stress in conditioning the reproductive strategy. Observations of character variations among plants from those populations in a uniform condition proved that the seedling population was of an annual type while those performing mixed sexual and asexual propagations were of an intermediate perennial-annual type. Isoenzymic variations controlled by alleles at two known loci indicated that the two intermediate populations were highly polymorphic and heterozygous. One of them consisted of nine separate clumps which differed in their characteristics. On the basis of these observations, the dynamics of differentiation of this species in adaptive strategy is discussed. It is further suggested that the intermediate perennial-annual type is probably the wild progenitor ofO. sativa. Contribution from National Institute of Genetics, Japan, No. 1308. Partly presented by H.I. Oka at a Symposium, “Problems in evolutionary and population genetics”, XIV International Congress of Genetics, Moscow, August 1978.     

Factors limiting the distribution of the annual legumeKummerowia striata in a river floodplain

The annual legumeKummerowia striata often predominates in river floodplains forming a large population, but it is rare in gravelly areas adjacent to it. In order to clarify the factors limiting the distribution ofK. striata, its distribution pattern, germination and survival of seeds sown artificially were studied in the floodplain of the Ohta River. There was a positive correlation between the cover value ofK. striata and the percentage of fine particles (<0.2 mm) in the soil. In the winter season, there was a number of seeds (up to 47 seeds 20 cm⁻²) on the ground where aK. striata population had existed in the previous year, but they were very sparse in areas apart from the population. Only a small proportion of seeds sown in the gravelly area germinated. Many of the germinated individuals died before the first leaf unfolded, but the rest survived to maturity despite repeated floodings. Plants germinated in the gravelly area and those inoculated with soil from the gravelly area bore nodules, showing the presence ofRhizobium in the gravelly area. It was concluded that the colonization ofK. striata in the gravelly area was limited by slow dispersal, and by a low percentage of germination and high mortality in the early stage of establishment.     

Seed bank persistence of clonal weeds in contrasting habitats: implications for control

The ability of weeds to form a seed bank is important for their population dynamics and management because it provides a refuge enabling reinvasion after established target plants have died. However, knowledge of the differential seed behaviour of individual species over multiple years and varying environmental conditions is surprisingly rare but necessary for effective control of diverse weed populations. We established a seed burial experiment in alpine habitats differing in management regime (i.e., forest, hay meadow and pasture) to determine whether seeds of the unpalatable perennial weeds, Veratrum album (white hellebore) and Gentiana lutea (yellow gentian) were able to delay germination and remain viable over 3 years. Our study shows that both species formed a short-term persistent seed bank; in the third-year, the soil seed banks of both species were nearly depleted, having declined to <5% of their original size. Both species had strikingly different germination strategies: G. lutea seeds mainly germinated in their first-year, whilst the majority of V. album seeds germinated in their second-year. The fraction of dormant G. lutea seeds increased with seed age, indicating that seeds remained viable after forgoing germination in the previous year. Habitat-specific differences in seed germination increased with seed age, with germination fractions being lowest in moist hay meadows. This suggests that the negative effects of anoxic conditions became more pronounced as seeds aged in hay meadows. Conversely, seed dormancy was equal among habitats. The absence of a long-term persistent seed bank has important implications for the management of both nuisance and endangered-plant populations. In the case of V. album and G. lutea, re-colonization of habitats from the seed bank is unlikely after established plants have been removed.     

Comparative studies on the reproductive systems ofMazus japonicus andM. miquelii (Scrophulariaceae)

Mazus japonicus is predominantly self-pollinated,M. miquelii mostly cross-pollinated, with a low degree of self-incompatibility. Correlated differences effect structure, development and seismonasty of the stigma, spatial relationships of stigma and anthers, and pollinator visits.M. japonicus produces numerous and light,M. miquelii fewer and heavier seeds. Growth experiments under different temperature regimes demonstrate thatM. japonicus dies after flowering and fruiting, and behaves as an annual, whileM. miquelii has additional asexual propagation and is clearly perennial.M. japonicus grows in somewhat drier and more disturbed habitats thanM. miquelii.     

两种集合繁殖体形态及间歇性萌发特性——以蒺藜和欧夏至草为例

集合繁殖体(synaptospermy)是荒漠植物为适应恶劣环境条件而演化出的关键性特征,其作为植物生活史特性之一,有助于了解在荒漠环境下集合繁殖体植物的适应策略。蒺藜(Tribulus terrestris)和欧夏至草(Marrubium vulgare)分别为一年生及多年生草本植物,蒺藜扩散单位由一朵花发育而成的集合繁殖体组成,欧夏至草扩散单位由多朵花发育的集合繁殖体和种子组成,以这两种植物为材料,对其集合繁殖体形态、活力、吸水及萌发特性进行初步研究。结果显示:(1)蒺藜集合繁殖体依照发育成熟先后位置在质量、附属物刺的长度、附属物占质量百分比、种子数、活力、吸水量、萌发率及萌发速率均存在显著差异;欧夏至草集合繁殖体质量及吸水量明显大于种子,而活力、萌发率及萌发速率不存在显著差异。(2)萌发位置上,蒺藜集合繁殖体仅在长刺端位置的种子萌发,属非随机萌发,而欧夏至草集合繁殖体萌发不具有规律性,属随机萌发;萌发时间上,蒺藜和欧夏至草集合繁殖体在当季下均只萌发部分种子,具间歇性萌发特性。(3)对不同生活型植物而言,其集合繁殖体附属物对种子的保护、保水、扩散及萌发行为的功能相同,但一年生草本植物的萌发行为侧重于种群繁衍,因此蒺藜集合繁殖体在当季萌发率及萌发速率较高;多年生草本植物的萌发行为侧重于种群扩散,因此欧夏至草扩散单位多样化,且萌发率及萌发速率较低。     

Coexistence and interference between a native perennial grass and non-native annual grasses in California

Little is known about the potential for coexistence between native and non-native plants after large-scale biological invasions. Using the example of native perennial bunchgrasses and non-native annual grasses in California grasslands, we sought to determine the effects of interference from non-native grasses on the different life stages of the native perennial bunchgrass Nassella pulchra. Further, we asked whether N. pulchra interferes with non-native annual grasses, and whether competition for water is an important component of these interspecific interactions in this water-limited system. In a series of field and greenhouse experiments employing neighbor removals and additions of water, we found that seedling recruitment of N. pulchra was strongly seed-limited. In both field and greenhouse, natural recruitment of N. pulchra seedlings from grassland soil was extremely low. In field plots where we added seeds, addition of water to field plots increased density of N. pulchra seedlings by 88% and increased total aboveground N. pulchra seedling biomass by almost 90%, suggesting that water was the primary limiting resource. In the greenhouse, simulated drought early in the growing season had a greater negative effect on the biomass of annual seedlings than on the seedlings of N. pulchra. In the field, presence of annuals reduced growth and seed production of all sizes of N. pulchra, and these effects did not decrease as N. pulchra individuals increased in size. These negative effects appeared to be due to competition for water, because N. pulchra plants showed less negative pre-dawn leaf water potentials when annual neighbors were removed. Also, simply adding water caused the same increases in aboveground biomass and seed production of N. pulchra plants as removing all annual neighbors. We found no evidence that established N. pulchra plants were able to suppress non-native annual grasses. Removing large N. pulchra individuals did not affect peak biomass per unit area of annuals. We conclude that effects of interference from non native annuals are important through all life stages of the native perennial N. pulchra. Our results suggest that persistence of native bunchgrasses may be enhanced by greater mortality of annual than perennial seedlings during drought, and possibly by reduced competition for water in wet years because of increased resource availability. Received: 12 November 1998 / Accepted: 4 August 1999     

EFFECT OF SEED SIZE ON SEEDLING SUCCESS IN THREE SPECIES OF SESBANIA (FABACEAE)

Variation in seed size may produce variation in seedling fitness, but the relationship is not simple. Differences in seed size within and among species may not have the same effects. We examined effects of differences in seed size within and among three species of Sesbania, S. macrocarpa, S. drummondii, and S. vesicaria, on seedling emergence and growth in the greenhouse and the field. Of the three species, the largest-seeded species, S. vesicaria, produced the largest, longest-lived seedlings in both the greenhouse and the field. Even though plant size differed, annual S. macrocarpa produced the same seed mass as annual S. vesicaria in the greenhouse. Within-species effects were less clear. In the greenhouse, S. vesicaria seedlings grown from large seeds remained largest until maturity, but the other species did not exhibit this effect. Some persistent within-species effects of seed size differences on height were observed in the field in 1981, but not in 1980, suggesting that field conditions increase the importance of seed size differences. Unscarified S. drummondii seeds germinated before seeds of the two annual species. Within species, larger seeds of the annuals and smaller seeds of the perennial germinated first. Differences among the species in the importance of seed size to seedling fitness may allow the species to have different patterns of regulation of reproduction in response to stress. Sesbania vesicaria showed the largest within-species effects of seed size and has the lowest plasticity in seed size, suggesting that patterns of plasticity have been selected such that the most important component of yield varies least.     

Factors affecting the population dynamics of Suaeda maritima at initial stages of development

This study describes life history and population dynamics of the annual halophyte Suaeda maritima, at initial stages of seedling development, in salt-marshes of the Mont-Saint-Michel Bay. Effects of salinity on seed germination and seedling development were studied both in the laboratory and in the field. Salinity was measured as sediment electrical conductivity. Experiments in the laboratory showed that Suaeda maritima was relatively tolerant to salinity during the germination stage. In the field, germination occurred when soil salinity was minimal. Almost all seeds germinated in the field; this may explain the absence of a persistent seed bank. Salinity did not seem to affect the growth of seedlings either. Mortality in the field was attributed to physical factors such as anoxia during temporary immersion, burial by sediment and tidal uprooting. The intensity of these effects varied according to the location of Suaeda maritima seedlings: in hollows, along the edge of tidal creeks, in gaps among dense vegetation cover, or in pattern with Puccinellia maritima. Perennial vegetation did not restrict Suaeda maritima germination. In contrast, perennials such as Puccinellia maritima and Halimione portulacoides limited the development of Suaeda maritima seedlings since only a small number of this annual emerged beneath their canopies. The fate of seedlings depended to a great extent on the permeability of the perennial canopy to light. Thus, disturbance resulting in bare patches inside the perennial vegetation seemed essential for the development of this annual species. Suaeda maritima can grow in the presence of Puccinellia maritima so long as the latter present as an open matrix. Suaeda maritima may also benefit from protection against desiccation and tidal action where this occurs.     

GERMINATION ECOPHYSIOLOGY OF ARENARIA GLABRA,A WINTER ANNUAL OF SANDSTONE AND GRANITE OUTCROPS OF SOUTHEASTERN UNITED STATES

The germination ecophysiology of Arenaria glabra Michx., a characteristic winter annual plant species of granite and sandstone outcrops of southeastern United States, was investigated. Seeds germinate in early autumn, plants overwinter in the rosette stage and then flower, set seeds, and die in late spring; seeds are dispersed soon after maturity. Eighty-five to 90% of freshly-matured seeds were innately dormant, and the other 10–15% germinated only at temperatures lower than those that occur in the habitat at the time of seed dispersal in June. During the summer after-ripening period, seeds stored dry under ambient laboratory conditions exhibited progressive increases in rates and total percentages of germination, a widening of the temperature range for germination, and a loss of the light requirement. At a 14-hr daily photoperiod, seeds kept on continuously moist soil germinated to 83% at simulated July and August temperatures during July and August, and the remainder germinated at September temperatures in September. On the other hand, seeds subjected to alternate wetting and drying during July and August germinated to only 9% during those 2 months, and the remainder germinated after the soil was kept continuously moist, beginning on 1 September, at simulated habitat temperatures during September and October. Thus, the timing of germination of A. glabra in the field is controlled by an interplay of the seeds' physiological state with the dynamics of temperature and soil moisture conditions.     

Do annual and perennial populations of an insect-pollinated plant species differ in mating system?

Background and AimsTheory predicts that outcrossing should be more prevalent among perennials than annuals, a pattern confirmed by comparative evidence from diverse angiosperm families. However, intraspecific comparisons between annual and perennial populations are few because such variation is uncommon among flowering plants. Here, we test the hypothesis that perennial populations outcross more than annual populations by investigating Incarvillea sinensis, a wide-ranging insect-pollinated herb native to China. The occurrence of both allopatric and sympatric populations allows us to examine the stability of mating system differences between life histories under varying ecological conditions.MethodsWe estimated outcrossing rates and biparental inbreeding in 16 allopatric and five sympatric populations in which both life histories coexisted using 20 microsatellite loci. In each population we measured height, branch number, corolla size, tube length and herkogamy for ~30 individuals. In a sympatric population, we recorded daily flower number, pollinator visitation and the fruit and seed set of annual and perennial plants.Key ResultsAs predicted, outcrossing rates (t) were considerably higher in perennial (mean = 0.76) than annual (mean = 0.09) populations. This difference in mating system was also maintained at sympatric sites where plants grew intermixed. In both allopatric and sympatric populations the degree of herkogamy was consistently larger in outcrossing than selfing plants. Perennials were more branched, with more and larger flowers than in annuals. In a sympatric population, annuals had a significantly higher fruit and seed set than perennials.ConclusionsGenetically based differences in herkogamy between annuals and perennials appear to play a key role in governing outcrossing rates in populations, regardless of variation in local ecological conditions. The maintenance of mating system and life history trait differentiation between perennial and annual populations of I. sinensis probably results from correlated evolution in response to local environmental conditions.     

Germination Response Patterns during Dormancy Loss in Achenes of Six Perennial Asteraceae from Texas, USA

Abstract When subjected to simulated habitat temperatures, achenes of six perennial Asteraceae from southcentral Texas came out of dormancy during summer. In the early stages of dormancy loss, achenes of Erigeron modestus, Gaillardia suavis and Hymenoxys scaposa germinated (to ≥ 10%) in light at 12/12 hr daily thermoperiods of 15/6, 20/10 and 25/15°C and those of Pinaropappus roseus at 15/6 and 20/10°C. After additional dormancy loss, achenes of these four species also germinated at 30/15 and 35/20°C. Achenes of these four species had a Type 1 germination response pattern, which heretofore has not been reported in perennial Asteraceae. Achenes of Chaptalia nutans first germinated (to ≥ 10%) at 20/10 and 25/15°C and those of Hymenopappus scabiosaeus at 20/10°C, but with further loss of dormancy achenes of both species also germinated at 15/6, 30/15 and 35/20°C. Thus, achenes of these two species had a Type 3 pattern. This is the first report of perennials in any family with a Type 3 response pattern whose seeds come out of dormancy during summer. Presence of annual and perennial Asteraceae with Type 2 in temperate eastern North America and annual and perennial Asteraceae with Type 1 in southcentral Texas causes us to conclude that climate is more important than the type of life cycle in determining the type of germination response pattern.     

Host specificity ofAcanthoscelides quadridentatus andA. Puniceus [Col.: Bruchidae] for biological control ofMimosa pigra (with preliminary data on their biology)

The biology and host specificity of the seed-feeding bruchids,Acanthoscelides quadridentatus (Schaeffer) andA. puniceus Johnson, from Mexico were studied in quarantine facilities in Australia. Distinguishing characters in the genitalia of each species are illustrated. Oviposition was recorded on 16 of 73 species of plants tested but larvae died without entering pods or seeds, except onMimosa invisa K. F. P. von Martius andM. pigra L. Larvae entering seeds ofM. invisa died in the first instar. The bruchids were clearly specific toM. pigra and were subsequently released as part of a program for biological control of this weed in the Northern Territory, Australia in April 1983 and thailand in July 1984.      

Comparative studies on the reproductive systems ofCardamine flexuosa,C. impatients,C. scutata,andC. lyrata,cruciferae

The reproductive systems of fourCardamine species were compared.C. flexuosa ssp.flexuosa, a self-pollinated winter annual in fallow paddy fields, produces numerous small seeds.C. flexuosa ssp.fallax, a self-pollinated year-long annual in gardens and roadsides, also produces many small seeds.C. impatiens, a self-pollinated annual in forest margins, similarly produces numerous small seeds.C. scutata is a self-pollinated perennial in ill-drained paddy fields and creeks; its vegetative reproduction is not predominant, and it produces relatively many seeds.C. lyrata, a cross-pollinated perennial with self-incompatibility in ill-drained paddy fields and creeks, produces fewer and heavier seeds, but it does produce many ramets. Moreover, in seed-dispersal mechanisms and germination behavior of fourCardamine species several adaptive characteristics to their habitats are found. These observations on the reproductive systems of fourCardamine species apparently present different characteristics of life-history strategy for each of them.     

Characterization of expressed sequence tag‐derived microsatellites from the kuruma prawn,Marsupenaeus japonicus

The kuruma prawn, Marsupenaeus japonicus, is a commercially important benthic marine crustacean in East Asia. Understanding the species’ population structures will be very important for its proper stock assessment and management strategy. Herein, 13 polymorphic microsatellite loci originating from expressed sequence tag libraries of M. japonicus were isolated and characterized. Number of alleles per locus ranged from two to 15, observed and expected heterozygosities ranged from 0.250 to 0.906 and from 0.310 to 0.932, respectively. The adequate level of variability within the population renders these microsatellite loci ideal markers for population genetic analysis of M. japonicus.     

Isozyme Variability in Plants Regenerated from Calli of Cereus peruvianus (Cactaceae)

Morphological and isozyme variation was observed among plants regenerated from callus cultures of Cereus peruvianus. Different morphological types of shoots (68%) were observed in 4-year-old regenerated plants, while no distinct morphological variants were observed in plants grown from germinated seeds. Isozyme patterns of 633 plants regenerated from calli and of 261 plants grown from germinated seeds showed no variation in isocitrate dehydrogenase isozyme, and the differential sorbitol dehydrogenase, alcohol dehydrogenase, malate dehydrogenase, acid phosphatase, and peroxidase isozyme patterns observed in regenerated plants were attributed to nonallelic variation. Allelic variation was detected at three isoesterase loci. The proportion of polymorphic loci for both populations was 13.6% and the deviation from Hardy–Weinberg equilibrium for the Est-1 and Est-7 loci observed in somaclones was attributed to the manner in which the regenerant population was established. The high values for genetic identity among regenerant and seed-grown plant populations are in accordance with the low levels of interpopulation genetic divergence. In somaclones of C. peruvianus, morphological divergence was achieved within a short time but was not associated with any isozyme changes and also was not accompanied by biochemical genetic divergence.     

Variation within and among the chloroplast genomes ofMelaleuca alternifolia andM. linariifolia (Myrtaceae)

Melaleuca alternifolia andM. linariifolia are commercially important Australian species harvested for their essential oils. Both species have relatively narrow and disjunct distributions on the central coast of eastern Australia. Variation in the chloroplast genome was assessed for eight individuals from each of twelve populations, representing the species' geographic range. Low nucleotide diversity withinM. alternifolia contrasted with high nucleotide diversity inM. linariifolia. CpDNA data are consistent with the southern population ofM. alternifolia being a hybrid population withM. linariifolia. The two species are sympatric in this region. Variation inM. linariifolia was geographically structured, with northern populations differing from southern populations by seven restriction site mutations, five length mutations and an inversion. There was no evidence of hybridisation of the cp genome of northernM. linariifolia with the partially sympatric speciesM. trichostachya. Intra- and interspecific variation in the chloroplast genomes ofM. alternifolia, M. linariifolia, andM. trichostachya indicate considerable potential for the use of intraspecific cpDNA studies in examining phylogenetic relationships in melaleucas.     

Population dynamics of annuals in perennial grassland controlled by ants and environmental stochasticity

Questions: In a system of five annual plant species restricted to nest‐mounds of the ant Lasiusflavus in a perennial grassland: 1. Are the population dynamics influenced by ant disturbance? 2. Is the survival of the annuals at the scale of the whole grassland possible under the observed conditions of disturbance dynamics? 3. Which phases in the annuals’ life cycle and patch types contribute most to population growth? Location: Borec hill, northern Czechia, 50°31’ N, 13°59’ E, 446 m a.s.l. Methods: Local population dynamics of the annuals were analysed separately for five patch types that differed in the proportion of bare soil. Vitality rates were assessed directly in the field, but also in a garden experiment, during 2000–2001 and 2001–2002. Population dynamics at the scale of the whole grassland was analysed with a megamatrix approach, combining patch dynamics of the nest‐mounds with patch‐specific population dynamics. Contributions of different phases and patch types to growth rate were estimated by elasticity analysis. Results: Nest‐mounds differed in the percentage of bare soil. Increasing moss cover significantly reduced germination and seed production of all studied annuals and decreased their population growth rates (λ). Although successional processes dominated over ant disturbance, populations of all species could survive well (λ? 1) in the grassland according to the 2000–2001 megamatrix dynamics. Based on the dynamics from the following period, two species would not survive in a long‐term perspective due to random environmental variation. Whereas the A‐A transition (adult plants originating from adults of the previous year) had the highest elasticity under open conditions and ‘good period’ demography, the importance of persistent seeds increased under reverse conditions. This, however, differed among species. Conclusions: Ant‐disturbance was shown to be critical for the population survival of five annual species in the studied grassland. The fate of the annual populations in the grassland system also depends on random environmental variation, which may override the effect of ant activity.     

Populational dynamics of three annual species of alpine plants in the Rocky Mountains

Summary Survivorship, fecundity, and seed bank size were measured over two years in alpine populations of the annuals, Koenigia islandica, Polygonum confertiflorum, and P. douglasii. The major loss of individuals from all populations occurred between seed dispersal and germination. Survival of vegetative plants to maturity was high in all species, usually above 80%, and the average number of seeds produced per plant was less than 10 in all species in both years. Seed banks existed for all three species but were small since more than 80% of the viable seeds in the soil germinated in the spring. Both survival and fecundity were negatively correlated with density in P. confertiflorum. These patterns of population dynamics are similar to those found in many annuals of temperate environments.     

Germination traits and seed-bank dynamics of a biennial plant,Oenothera glazioviana Micheli

A study was conducted on the germination traits and seed-bank dynamics ofOenothera glazioviana (=O. erythrosepala), which sets seed in August in sand-dune systems in Japan. More than 90% of freshly matured seeds germinated over a wide range of temperature in light, but less than 10% did so in continuous darkness. Stratification (chilling under moist conditions) was ineffective in diminishing the light-requirement for germination. When fresh seeds were imbibed for 24 h including a 12-h light period, followed by 7-day air-drying, 94% of them became germinable in the dark at 25°C, but remained dormant at less than 15°C. of seeds collected in March from capsules of dead plants, 58% germinated in the dark at 25°C. After four cycles of alternatc 1-day wetting followed by 2-day drying or 1.5-day wetting followed by 1.5-day drying under a 12-h photoperiod, the fraction of viable seeds declined from 76% to 40% and 22%, respectively, due to germination during the wet periods. Seed-bag experiments were conducted in the field, using seeds given and not given a light-stimulus. Forty percent of the light-stimulated seeds germinated in the soil, whereas the seeds without a light-stimulus remained dormant throughout the experiment. When seeds were placed on the soil surface or at a depth of 0.5-1 cm, the proportion of germinable seeds declined during late spring and autumn, but not during winter and early spring. The seed-bank size of a natural population just prior to current seed dispersal was 2–3% of the seed production in the previous year, suggesting a high turnover rate of the seed-bank.     

Historical distribution and regional dynamics of two Brassica species

Plants often show a patchy distribution. This can be related to the discontinuous distribution of environmental variables that define suitable habitat. Metapopulation theory suggests that additional patchiness may be caused by the dynamics of local extinctions and recolonisations. However, the contribution of these two mechanisms to explaining the observed patterns, and thus the applicability of metapopulation theory to plants remains controversial partly because population turnover may occur at long time‐scales not usually covered by ecological studies. We analyzed the role of environmental variation and population turnover in determining the distribution of two Brassica species, an annual and a perennial, along 44 km of coastline in Dorset, UK. Mapped occurrence and abundance of both species in recent years was compared with distributions from a 70 yr‐old dataset and a survey of present‐day environmental parameters. Abiotic and vegetation parameters were correlated with the occurrence of both species in binary logistic regression models and explained spatial auto‐correlation in the Brassica distributions. These regression models suggest that neither species is occupying all potential habitat in the region studied. The relationship between historical and present distributions differed between the species. While an historical signal was very weak in the annual B. nigra, it had a large influence in predicting the present distribution of the perennial B. oleracea. This suggests local extinction and colonisation events for B. nigra over the 70 yr period, but not for B. oleracea which showed little evidence of population turnover. Our results demonstrate that the consideration of large time‐scales can reveal patterns of regional dynamics. We conclude that metapopulation dynamics might be possible for our annual but can be ruled out for our perennial study species over the past 70 yr. We argue that beyond this time‐scale possible metapopulation dynamics may be overridden by faster processes of environmental change.