14 research outputs found
Geographical and climatic limits of needle types of one- and two-needled pinyon pines
Aim The geographical extent and climatic tolerances of one- and two-needled pinyon pines (Pinus subsect. Cembroides) are the focus of questions in taxonomy, palaeoclimatology and modelling of future distributions. The identification of these pines, traditionally classified by one- versus two-needled fascicles, is complicated by populations with both one- and two-needled fascicles on the same tree, and the description of two more recently described one-needled varieties: the fallax-type and californiarum-type. Because previous studies have suggested correlations between needle anatomy and climate, including anatomical plasticity reflecting annual precipitation, we approached this study at the level of the anatomy of individual pine needles rather than species.
Location Western North America.
Methods We synthesized available and new data from field and herbarium collections of needles to compile maps of their current distributions across western North America. Annual frequencies of needle types were compared with local precipitation histories for some stands. Historical North American climates were modeled on a c. 1-km grid using monthly temperature and precipitation values. A geospatial model (ClimLim), which analyses the effect of climate modulated physiological and ecosystem processes, was used to rank the importance of seasonal climate variables in limiting the distributions of anatomical needle types.
Results The pinyon needles were classified into four distinct types based upon the number of needles per fascicle, needle thickness and the number of stomatal rows and resin canals. The individual needles fit well into four categories of needle types, whereas some trees exhibit a mixture of two needle types. Trees from central Arizona containing a mixture of Pinus edulis and fallax-type needles increased their percentage of fallax-type needles following dry years. All four needle types occupy broader geographical regions with distinctive precipitation regimes. Pinus monophylla and californiarum-type needles occur in regions with high winter precipitation. Pinus edulis and fallax-type needles are found in regions with high monsoon precipitation. Areas supporting californiarum-type and fallax-type needle distributions are additionally characterized by a more extreme May–June drought.
Main conclusions These pinyon needle types seem to reflect the amount and seasonality of precipitation. The single needle fascicle characterizing the fallax type may be an adaptation to early summer or periodic drought, while the single needle of Pinus monophylla may be an adaptation to summer–autumn drought. Although the needles fit into four distinct categories, the parent trees are sometimes less easily classified, especially near their ancestral Pleistocene ranges in the Mojave and northern Sonoran deserts. The abundance of trees with both one- and two-needled fascicles in the zones between P. monophylla, P. edulis and fallax-type populations suggest that needle fascicle number is an unreliable characteristic for species classification. Disregarding needle fascicle number, the fallax-type needles are nearly identical to P. edulis, supporting Little’s (1968) initial classification of these trees as P. edulis var. fallax, while the californiarum-type needles have a distinctive morphology supporting Bailey’s (1987) classification of this tree as Pinus californiarum
A seed predator drives the evolution of a seed dispersal mutualism
Although antagonists are hypothesized to impede the evolution of mutualisms, they may simultaneously exert selection favouring the evolution of alternative mutualistic interactions. We found that increases in limber pine (Pinus flexilis) seed defences arising from selection exerted by a pre-dispersal seed predator (red squirrel Tamiasciurus hudsonicus) reduced the efficacy of limber pine's primary seed disperser (Clark's nutcracker Nucifraga columbiana) while enhancing seed dispersal by ground-foraging scatter-hoarding rodents (Peromyscus). Thus, there is a shift from relying on primary seed dispersal by birds in areas without red squirrels, to an increasing reliance on secondary seed dispersal by scatter-hoarding rodents in areas with red squirrels. Seed predators can therefore drive the evolution of seed defences, which in turn favour alternative seed dispersal mutualisms that lead to major changes in the mode of seed dispersal. Given that adaptive evolution in response to antagonists frequently impedes one kind of mutualistic interaction, the evolution of alternative mutualistic interactions may be a common by-product
Subspecialty training in Europe: A report by the European Network of Young Gynaecological Oncologists
Background ESGO (European Society of Gynaecological Oncology) and partners are continually improving the developmental opportunities for gynaecological oncology fellows. The objectives of this survey were to evaluate the progress in the infrastructure of the training systems in Europe over the past decade. We also evaluated training and assessment techniques, the perceived relevance of ENYGO (European Network of Young Gynaecological Oncologists) initiatives, and unmet needs of trainees. Methodology National representatives of ENYGO from 39 countries were contacted with an electronic survey. A graduation in well/moderately/loosely-structured training systems was performed. Descriptive statistical analysis and frequency tables, as well as two-sided Fisher's exact test, were used. Results National representatives from 33 countries answered our survey questionnaire, yielding a response rate of 85%. A national fellowship is offered in 22 countries (66.7%). A logbook to document progress during training is mandatory in 24 (72.7%) countries. A logbook of experience is only utilized in a minority of nations (18%) for assessment purposes. In 42.4% of countries, objective assessments are recognized. Trainees in most countries (22 (66.7%)) requested additional training in advanced laparoscopic surgery. 13 (39.4%) countries have a loosely-structured training system, 11 (33.3%) a moderately-structured training system, and 9 (27.3%) a well-structured training system. Conclusion Since the last publication in 2011, ENYGO was able to implement new activities, workshops, and online education to support training of gynaecological oncology fellows, which were all rated by the respondents as highly useful. This survey also reveals the limitations in establishing more accredited centers, centralized cancer care, and the lack of laparoscopic training. © 2021 BMJ Publishing Group. All rights reserved