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Full-Text Articles in Biology

The Rare, Serpentine Endemic Streptanthus Morrisonii (Brassicaceae) Species Complex, Revisited Using Isozyme Analysis, Rebecca W. Dolan Mar 2010

The Rare, Serpentine Endemic Streptanthus Morrisonii (Brassicaceae) Species Complex, Revisited Using Isozyme Analysis, Rebecca W. Dolan

Rebecca W. Dolan

The Streptanthus morrisonii (Brassicaceae) complex is a group of six narrowly-distributed obligate serpentine endemic taxa whose habitat is threatened by geothermal development. Isozyme analysis of this little-studied complex supports the delineation of two species, S. morrisonii and S. brachiatus, but is at odds with the treatment of two subspecies based on morphology. These results may be influenced by small sample sizes but genetic studies of other Streptanthus taxa have shown patterns of relatedness that often transgress subspecies boundaries based on morphology. The present study further shows that members of the S. morrisonii complex share high genetic identity values (mean = …


Population Genetic Structure In Nolina Brittoniana (Agavaceae), A Plant Endemic To The Central Ridges Of Florida, Rebecca W. Dolan, Rebecca Yahr, Eric S. Menges Mar 2010

Population Genetic Structure In Nolina Brittoniana (Agavaceae), A Plant Endemic To The Central Ridges Of Florida, Rebecca W. Dolan, Rebecca Yahr, Eric S. Menges

Rebecca W. Dolan

Nolina brittoniana is endemic to the central ridges of peninsular Florida. Its scrub and sandhill habitats have suffered extensive anthropogenic modification. Analysis of isozymes from populations throughout its range revealed less genetic variation than generally reported for endemic plants. Populations were well differentiated, with significant clines in allele frequency along the north-south axis of distribution. Pair-wise F-statistics calculated at four levels of population geographic substructure revealed that current and inferred historical habitat patches had similar genetic structure. We found no evidence of recent bottlenecks or changes in genetic structure due to habitat loss and fragmentation, consistent with populations having always …


The Effects Of Seed Size And Maternal Origin On The Distribution Of Individual Plant Size In Ludwigia Leptocarpa (Onagraceae), Rebecca W. Dolan Mar 2010

The Effects Of Seed Size And Maternal Origin On The Distribution Of Individual Plant Size In Ludwigia Leptocarpa (Onagraceae), Rebecca W. Dolan

Rebecca W. Dolan

Seed size is normally distributed for many annual species, while mature plant size is frequently positively skewed. A study was conducted to determine the influence of seed size and the role of genetic differences in determining relative seedling size for Ludwigia leptocarpa. Seed size had a significant effect on percentage germination and time of seed germination but no effect on dry weight or leaf area of seedlings. Seed size and spacing had a significant effect on seedling dry weight for plants grown under competition, while relative day of emergence had no effect. Familial (genetic) differences were found in average seed …


Patterns Of Isozyme Variation In Relation To Population Size, Isolation, And Phytogeographic History In Royal Catchfly, Rebecca W. Dolan Mar 2010

Patterns Of Isozyme Variation In Relation To Population Size, Isolation, And Phytogeographic History In Royal Catchfly, Rebecca W. Dolan

Rebecca W. Dolan

The distribution of genetic variation within and among plant populations is influenced by both contemporary and historical factors. I used isozyme analysis of band phenotypes to examine genetic structure in the rare prairie forb Silene regia. Relationships between current-day population size, isolation, and phenotypic variation were assessed for 18 populations in two regions with differing postglacial history. Western populations from unglaciated southern Missouri and Arkansas were more genetically diverse based on the Shannon-Weaver index (H) and a polymorphic index than were more eastern populations. These differences may be due to loss of variation with repeated founding of new populations in …


Conservation Implications Of Genetic Variation In Three Rare Species Endemic To Florida Rosemary Scrub, Rebecca W. Dolan, Rebecca Yahr, Eric S. Menges, Matthew Halfhill Mar 2010

Conservation Implications Of Genetic Variation In Three Rare Species Endemic To Florida Rosemary Scrub, Rebecca W. Dolan, Rebecca Yahr, Eric S. Menges, Matthew Halfhill

Rebecca W. Dolan

Habitat conversion and fire suppression during the last 50 yr have greatly reduced and altered Florida scrub vegetation, resulting in threats to the persistence of its unique flora. As part of a larger conservation project, we investigated patterns of isozyme variation in three rare perennial scrub plants with overlapping ranges endemic to Florida rosemary scrub on the Lake Wales Ridge. All three species have low levels of genetic variation, comparable to or lower than those generally reported for rare plants with restricted geographic ranges. Liatris ohlingerae has more than twice the expected heterozygosity of the other two species, with little …


Conservation Implications Of Genetic Variation In Three Rare Species Endemic To Florida Rosemary Scrub, Rebecca W. Dolan, Rebecca Yahr, Eric S. Menges, Matthew Halfhill Mar 2010

Conservation Implications Of Genetic Variation In Three Rare Species Endemic To Florida Rosemary Scrub, Rebecca W. Dolan, Rebecca Yahr, Eric S. Menges, Matthew Halfhill

Rebecca W. Dolan

Habitat conversion and fire suppression during the last 50 yr have greatly reduced and altered Florida scrub vegetation, resulting in threats to the persistence of its unique flora. As part of a larger conservation project, we investigated patterns of isozyme variation in three rare perennial scrub plants with overlapping ranges endemic to Florida rosemary scrub on the Lake Wales Ridge. All three species have low levels of genetic variation, comparable to or lower than those generally reported for rare plants with restricted geographic ranges. Liatris ohlingerae has more than twice the expected heterozygosity of the other two species, with little …


Genetic Diversity And Reproductive Biology In Warea Carteri (Brassicaceae), A Narrowly Endemic Florida Scrub Annual, Margaret E.K. Evans, Rebecca W. Dolan, Eric S. Menges, Doria R. Gordon Mar 2010

Genetic Diversity And Reproductive Biology In Warea Carteri (Brassicaceae), A Narrowly Endemic Florida Scrub Annual, Margaret E.K. Evans, Rebecca W. Dolan, Eric S. Menges, Doria R. Gordon

Rebecca W. Dolan

Carter's mustard (Warea carteri) is an endangered, fire-stimulated annual endemic of the Lake Wales Ridge, Florida, USA. This species is characterized by seed banks and large fluctuations in plant numbers, with increases occurring in postdisturbance habitat. We investigated the mating system, patterns of isozyme variation, and effective population sizes of W. carteri to better understand its population biology and to comment on reserve designs and management proposals relevant to this species. Warea carteri is self-compatible and autogamous, and probably largely selfing. Measures of genetic variation in W. carteri were lower than values reported for species with similar ecological and life …


Genetic Variation For Susceptibility To Storm-Induced Stem Breakage In Solidago Altissima: The Role Of Stem Height And Morphology, M. Wise, W. Abrahamson Dec 2009

Genetic Variation For Susceptibility To Storm-Induced Stem Breakage In Solidago Altissima: The Role Of Stem Height And Morphology, M. Wise, W. Abrahamson

Warren G. Abrahamson, II

While storms can have obvious ecological impacts on plants, plants’ potential to respond evolutionarily to selection for increased resistance to storm damage has received little study. We took advantage of a thunderstorm with strong wind and hail to examine genetic variation for resistance to stem breakage in the herbaceous perennial Solidago altissima. The storm broke the apex of nearly 10% of 1883 marked ramets in a common-garden plot containing 26 genets of S. altissima. Plant genets varied 20-fold in resistance to breakage. Stem height was strongly correlated with resistance to breakage, with taller stems being significantly more susceptible. A stem’s …


Spatiotemporal Variation Of Fruit Digestible-Nutrient Production In Florida's Uplands, J. Layne, W. Abrahamson Dec 2009

Spatiotemporal Variation Of Fruit Digestible-Nutrient Production In Florida's Uplands, J. Layne, W. Abrahamson

Warren G. Abrahamson, II

We examined annual total digestible nutrient (TDN) production by fruits of eight species (Quercus chapmanii, Q. geminata, Q. inopina, Q. laevis, Q. myrtifolia, Carya floridana, Sabal etonia, Serenoa repens) that account for the major proportion of TDN production by fruits and seeds in Florida’s xeric upland associations (southern ridge sandhill, sand pine scrub, scrubby flatwoods). Mean annual fruit TDN of all species combined over a 27-year span in sandhill and scrub and 24 years in scrubby flatwoods was highest (45.4 kg/ha) in sandhill, intermediate in scrubby flatwoods (28.8 kg/ha), and lowest in scrub (14.2 kg/ha). Sandhill fruit TDN production was …


Nomenclatural Changes For Some Grasses In California And The Muhlenbergia Clade (Poaceae), James Payne Smith Jr. Dec 2009

Nomenclatural Changes For Some Grasses In California And The Muhlenbergia Clade (Poaceae), James Payne Smith Jr.

James Payne Smith

No abstract provided.


Ducking As The Means Of Resistance In "Candy-Cane" Stems Of Goldenrod: Straightened Stems Lose Their Edge, M. J. Wise, W. G. Abrahamson, J. A. Cole Dec 2009

Ducking As The Means Of Resistance In "Candy-Cane" Stems Of Goldenrod: Straightened Stems Lose Their Edge, M. J. Wise, W. G. Abrahamson, J. A. Cole

Warren G. Abrahamson, II

Herbivores are among the most pervasive selective forces acting on plants, and the number of plant chemicals that presumably evolved for defense against herbivory is immense. In contrast, biologists are only beginning to appreciate the important roles that architectural traits can play in antiherbivore defense. One putative architectural-resistance trait is the nodding stem apex of some goldenrods (Solidago ; Asteraceae). Individuals of S. altissima genets that undergo temporary nodding in the late spring (i.e., “candy-cane ramets) have been shown to be more resistant than individuals of erect-stemmed genets to certain apex-attacking” herbivores. We tested the hypothesis that the greater resistance …


Nutrition As A Facilitator Of Host-Race Formation: The Role Of Food Quality In The Shift Of A Stem-Boring Beetle To A Gall Host, C. P. Blair, R. V. Schlanger, S. E. Diamond, W. G. Abrahamson Dec 2009

Nutrition As A Facilitator Of Host-Race Formation: The Role Of Food Quality In The Shift Of A Stem-Boring Beetle To A Gall Host, C. P. Blair, R. V. Schlanger, S. E. Diamond, W. G. Abrahamson

Warren G. Abrahamson, II

1. The importance of host-race formation to herbivorous insect diversity depends on the likelihood that successful populations can be established on a new plant host. A previously unexplored ecological aid to success on a novel host is better nutritional quality. The role of nutrition was examined in the shift of the stem-boring beetle Mordellistena convicta to fly-induced galls on goldenrod and the establishment there of a genetically distinct gall host race. 2. First, larvae of the host race inhabiting stems of Solidago gigantea were transplanted into stems and galls of greenhouse-grown S. gigantea plants. At the end of larval development, …