Perspectives in Plant Ecology Evolution and Systematics最新文献

The tempo and mode of colonization of the Iberian Peninsula (IP) by Cannabis sativa, its further internal spreading and the potential cultural and environmental factors involved remain unknown. The available continental-wide European meta-analyses using pollen and archeological evidence account for only a few IP sites, insufficient for a sound assessment. This paper presents a nearly comprehensive database of almost 60 IP sites with palynological evidence of Cannabis and analyzes the corresponding spatiotemporal patterns. The first scattered records of this pollen type date from the Middle and Upper Paleolithic (150–12 kyr BP) and would have entered the IP by maritime Mediterranean or terrestrial continental pathways, or both. A first burst of introductions, probably in a cultivated form, would have occurred during the Neolithic (7–5 kyr BP) using similar paths. Human participation in these Neolithic introductions remains unclear but cannot be dismissed. A period of reduced Cannabis arrivals (mostly via maritime pathway) occurred between the Chalcolithic and the Roman Epoch (4.5–2 kyr BP), when the innermost parts of the IP were colonized (Late Bronze). A second, likely anthropogenic, introduction acceleration took place in the Middle Ages (1.5 kyr BP onward) using the Mediterranean and the continental pathways. Maximum cultivation and hemp retting activity was recorded during the Modern Ages (16th-19th centuries), coinciding with the increased demand of hemp fiber to supply the Spanish royal navy for imperial expansion and commerce. A potential link between Cannabis colonization/introduction bursts and climatic warmings has been observed that should be tested with future studies. Regional moisture variations seem to be less influential. Further efforts to enhance and improve the database used in this study are encouraged. The results of this paper should be compared with archeological and historical evidence to clarify the role of human migrations and cultural changes in the historical biogeography of Cannabis in the IP.

The semi-domesticated nature of the reindeer (Rangifer tarandus L.) makes it a distinct case among the world’s herbivores. Here, we review the literature on how reindeer shape vegetation and soil carbon and nitrogen cycles in northernmost Fennoscandia. We first describe main historical events that shaped the present-day grazing patterns in the different countries, then discuss the methodological considerations needed for interpreting evidence from grazer exclosures in ecological and environmental contexts. We argue that it is critical to be aware that these experiments do not measure the effect of grazing per se, but rather, they measure the responses of existing ecosystem structure and function to the sudden cessation of grazing in an environment, which was to a large degree shaped by it. Studies show that the direction and the magnitude of the effects of reindeer on vegetation and soil processes vary across habitats and depend on both the current land-uses and the historically formed grazing regimes; knowledge of the history is thus a key prerequisite for understanding the role of reindeer in ecosystems. As a general trend, reindeer affect soil nutrient cycles to a stronger extent in subarctic than in boreal ecosystems. In sites where reindeer have changed soil nutrient availability, they indirectly modify vegetation and productivity even after the cessation of grazing. We reason that the concepts of cultural and natural landscapes are not mutually exclusive in the case of reindeer ranges. Understanding how the intensity and seasonal timing of both past and present grazing direct ecosystem changes under climate warming is crucial for predicting future ecosystem structures and functioning in northern Fennoscandia as well as ecosystems in general.

Capparis is the largest genus of the family Capparaceae, represented by 142 species in the tropics and subtropics of the Old World. Despite being one of the medicinally and economically important genera with its unique distribution pattern, the evolutionary history of Capparis remained unexplored. Moreover, the phylogenetic relationships, origin, dispersal, and character evolution of the genus were poorly understood. With the objectives to (i) test the congruence between the molecular and morphological datasets, (ii) validate Jacobs' hypothesis on the origin, dispersal, and speciation pattern of Capparis using new fossil data, and (iii) understand the possible evolutionary role of some key morphological characters, we sampled across the five speciation centres of Capparis. The results derived from three plastidial markers (matK, trnL-F and rbcL) revealed incongruence with the morphology based delimitations and suggested a new sectional classification in Capparis. Divergence dating analysis revealed that Capparaceae originated in Africa at 47.25 MYA and Capparis in Peninsular India at about 29.32 MYA. Capparis followed multiple forward and backward dispersal, supporting the “into and out of India” hypothesis. These dispersal events were consistent with the various land bridges in different parts of the Old World during the Eocene to Miocene. The only long-distance dispersal event was observed in the case of the New World Capparaceae, corroborating the earlier findings. Our results suggest West Asia to the North African region as another centre of speciation for Capparis and present a robust age estimate for the genus. The character state reconstruction of Capparis revealed a unique evolutionary adaptation due to exposure to various climatic conditions and the acquisition of suitable pollination strategies. We hypothesize that the gynophore length, sepal shape, and blotches on petals contribute substantially to the pollination success.

The invasive herb Lupinus polyphyllus has been focus of a number of fact sheets worldwide but a comprehensive summary of the species’ taxonomy and morphology, distribution, habitat requirements, and biology has been lacking. This paper gives a thorough account of the species’ systematic position and taxonomy, highlighting the difficulties to delimit taxa, which is related to interbreeding among members of this genus. However, L. polyphyllus var. polyphyllus is apparently the taxon that has naturalized and is regionally invasive in temperate-humid climates worldwide. We also present an updated distribution map of L. polyphyllus in the native and invaded ranges, which highlights seven regions in the world where the species has been established. We show that the climatic niche of L. polyphyllus in the invaded range shifts towards higher summer precipitation and lower isothermality, probably because the invaded range includes subcontinental regions of eastern Europe and western Siberia. The habitats of L. polyphyllus range from rather dry to wet, have moderately acidic to strongly acidic soils, and the species’ indicator values across Europe suggest that it occurs along a gradient from very nutrient poor sites to intermediate to rich sites from northern to southern Europe. The species shows high resistance to both drought and frost. In Central Europe, the species has a stronghold in alpic mountain hay meadows, abandoned meadows and pastures, low and medium altitude hay meadows, anthropogenic herb stands and temperate thickets and scrubs. In northern Europe, the species occurs in anthropogenic herb stands along roads and railroads as well as in abandoned pastures and fields. We also found some doubtful information about L. polyphyllus in the literature. This refers to its description as “rhizomatous perennial” although it lacks rhizomes; an apparently very high longevity of its seeds, which may only be true under artificial conditions in an ex situ seed repository; and a very deep rooting depth, which may not represent the average rooting depth but rather an extreme value. Knowledge about the interrelationships between the species’ future population dynamics and spread and ongoing climate warming is lacking. Finally, our review points out that there is currently no evidence-based strategy for a cost-efficient management of L. polyphyllus although it is among the most problematic non-native plant species in Europe due to its environmental and socio-economic impacts.

Inbreeding usually reduces offspring fitness (‘inbreeding depression’, ID), and may affect the plasticity of functional traits involved in the response to stress. ID is often found to increase under stress, but there are also reports of no effects or even a reduction of ID under stress. One reason for this variation that has received little attention may be related to different concepts of stress. In particular, the magnitude of ID may be unrelated to the effect of an environment on fitness (evolutionary stress concept), but increase particularly during the ‘alarm phase’ after a stress has been initiated (physiological stress concept). We clonally replicated inbred and outbred Mimulus guttatus plants, for which ID was known to increase under flooding. We exposed the clonal replicates to control and flooding conditions and harvested replicates of each genotype after two, six and 11 weeks of growth. As functional traits related to stress response we measured chlorophyll fluorescence, root mass and the production of stolons and adventitious roots. As fitness estimates we measured biomass and flower number, and we pollinated a subset of plants and grew a second generation of plants under control and flooding conditions to calculate multiplicative fitness. Overall, M. guttatus proved to be very flooding-tolerant. Chlorophyll fluorescence (F_v/F_m) was not influenced by flooding, but decreased with leaf age and increased after fertilization. At the end of the experiment, biomass and flower number (F₁ generation) as well as multiplicative fitness (including performance in the F₂ generation) were even higher under flooding than under control conditions. Flooding reduced the root mass in the pots, but increased the production of stolons and floating roots. Plasticity in these traits can be regarded as beneficial, although selection gradient analysis failed to identify plasticity in stolon number as adaptive. Only two functional traits were influenced by an interaction between flooding and inbreeding, early stolon length (suggesting a reduced flooding escape response of inbred plants) and root tissue density of floating adventitious roots (suggesting a reduced aeration of the roots of inbred offspring). ID in fitness-related traits was higher under flooding, but its magnitude changed strongly over the course of the experiment. ID under flooding was particularly high after two weeks (δ = 0.42 vs. 0.05 in the control), suggesting sensitivity of inbred plants to the initiation of flooding (‘alarm phase’ of stress response). This effect had disappeared after 6 weeks when plants had acclimated to ongoing flooding. However, under flooding ID increased again after 11 weeks, this time because outbred plants grew much better under flooded than control conditions, and the same pattern was found for the multipli