MORPHOLOGICAL VARIATION WITHIN AND BETWEEN NATURAL POPULATIONS OF NON-TIDE POOL FUCUS DISTICHUS (PHAEOPHYTA) IN NEW ENGLAND1,2

2004 ◽  
Vol 21 (2) ◽  
pp. 250-257 ◽  
Author(s):  
Eric J. Sideman ◽  
A. C. Mathieson
2018 ◽  
pp. 157-171 ◽  
Author(s):  
Dulce María Galván-Hernández ◽  
Manuel Alejandro Macedo-Villareal ◽  
Francisco Federico Núñez de Cáceres-González ◽  
Arturo Sánchez-González ◽  
Pablo Octavio-Aguilar

Background and Aims: Cedrela odorata (Spanish cedar) is a tropical tree native to America with an important international trade market. In this study, the morphological variation of C. odorata was compared among three conditions: logging, plantations, and natural populations, with the objective to evaluate the current condition of managed populations after harvesting and in plantations, in contrast to relatively well-preserved populations.Methods: Two sites were chosen for each condition. The population density and four morphological attributes were measured: diameter at breast height, height, angle of branch insertion and crown form. A multivariate approach was used to compare the morphological variation among conditions (generalized discriminant factors analysis) and determine total variation distributed among size classes (cluster analysis), as well as assignment of these classes to each condition (canonical correspondence analysis).Key results: Four significantly different size classes were identified among all populations with specific association to condition. Strongest correlations were between highest trees with natural populations and small trees with plantations. Forest management, including harvesting and plantation conditions, reduced the phenotypical variation and modified the dasometrical attributes of C. odorata. The logging of the better shaped phenotypes increased the smaller size trees frequency compared to commercial size individuals, and changed the forest composition favoring small categories.Conclusions: The forest exploitation generates homogenization in median height-class and the plantation in lower height-class. In both cases, the harvestable trees are scarce, even after 20 years of management; and they are non-existent in plantations of 15 years. These results suggest that the removal of the highest trees, as well as forest plantations, are not being effective to wood production since they do not reach commercial sizes in the time of recovery or projected growth. 


1991 ◽  
Vol 39 (6) ◽  
pp. 545 ◽  
Author(s):  
RJE Wiltshire ◽  
BM Potts ◽  
JB Reid

Ontogenetic and morphological variation in 40 natural populations of the closely related species, E. risdonii and E. tenuiramis, were assessed in a multivariate study of juvenile and adult leaf and fruit characters. The present taxonomic separation of the two taxa is based mainly on ontogenetic differences, but this study reveals that the variation between the two taxa in the retention of the juvenile leaf habit is continuous and may represent a paedomorphocline. The morphological data suggest that at least four phenetic groups are required to summarise the morphological variation in the E. risdonii/ E. tenuiramis complex. When ontogenetic variation is removed, the morphological variation between some E. risdonii and some E. tenuiramis populations is also continuous and much smaller than the morphological differences within E. tenuiramis. This suggests that E. risdonii may be the product of relatively recent changes in developmental timing (heterochrony) from E. tenuiramis.


Evolution ◽  
1947 ◽  
Vol 1 (4) ◽  
pp. 237-248 ◽  
Author(s):  
Harrison D. Stalker ◽  
Hampton L. Carson

1985 ◽  
Vol 88 (2) ◽  
pp. 207-215 ◽  
Author(s):  
E. L. Rice ◽  
T. J. Kenchington ◽  
A. R. O. Chapman

2020 ◽  
Vol 45 (1) ◽  
pp. 53-68 ◽  
Author(s):  
Fernando Pérez Uribbe ◽  
Beatriz Neves ◽  
Suara Souza Almeida Jacques ◽  
Andrea Ferreira da Costa

Abstract—The family Bromeliaceae is essentially Neotropical, with high endemism and diversity in the Atlantic Rainforest Domain. Species circumscription is a major problem in the family systematics, especially in the most diverse genera. Species of the Vriesea procera complex, which occur in forests and restinga (coastal vegetation) along the South American Atlantic coast from Venezuela to southern Brazil, share the same basic vegetative and reproductive morphological patterns. However, they vary widely in the number and position of inflorescence branches as well as in the dimensions, position, and shape of the leaves and flowers in different populations. Here we aimed 1) to evaluate the morphological variation in the V. procera complex, through morphometric analyses of natural populations along the Brazilian Atlantic Rainforest; and 2) to determine the taxonomic relationships among these species, establishing the validity and the limits of variation of the taxa through taxonomic treatment. Fourteen natural populations, 271 individuals, and 36 morphometric variables were analyzed. Kruskal-Wallis tests and discriminant analyses were conducted to test statistical differences between previously established groups. Of an original three species and three varieties, our data allowed us to recognize six species, including three new taxa (Vriesea aureoramosa, V. magna, V. rubroviridis) and one new name and status (V. flexuosa). The resulting taxa are distinguished by the inflorescence and leaf sizes and especially by floral characteristics such as the length of bracts, sepals, petals, stamens, and pistils, besides the petal apex posture and relative position of the stamen during anthesis. Recognition of cryptic species under the names V. procera and V. neoglutinosa is an important step toward a better understanding of the biodiversity of the Brazilian Atlantic Rainforest.


1971 ◽  
Vol 49 (8) ◽  
pp. 1463-1469 ◽  
Author(s):  
J. McLachlan ◽  
L. C.-M. Chen ◽  
T. Edelstein

Mature thalli of Fucus distichus, F. edentatus, F. serratus, and F. vesiculosus were obtained in unialgal culture from zygotes and were grown in an enriched seawater medium. The two former species were maintained in culture for more than 2 years, in which time the length of thalli of F. edentatus never exceeded 4 cm. The other species grew reasonably well with a maximum rate of elongation of about 1 cm per month for F. serratus. In all species the rates of growth were less than that observed in nature. Fertile receptacles with viable gametes were formed in F. distichus, but the other species never attained reproductive maturity. All specimens retained their characteristic morphology under identical conditions of culture, and it is suggested that morphological variation amongst Fucus spp. is due mainly to hybridization rather than to environmental conditions. There was no indication that any of these species required intertidal conditions, and no unique nutritional requirements were identified.


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