This dissertation is concerned with evaluating the nature of the interactions between Schomburgkia tibicinis (Orchidaceae) and a series of organisms (i.e., ants, bees, wasps, beetles, mealybugs) that inhabit the coastal sand dune vegetation of the State of Yucatan, Mexico. The objectives are: study the pollination biology of the orchid, assess the existence and the effect of an ant-guard type system on the reproductive fitness of the orchid, and determine the uptake by the orchid of organic material provided by the ants S. tibicinis harbors nine ant species in its hollow pseudobulbs; five of them are common (Crematogaster brevispinosa, Camponotus planatus, C. abdominalis, C. rectangularis, and Ectatomma tuberculatum), and interact readily with the orchid. The plant and the ants show a significant clumped distribution along the coast The orchid's reproductive season is from January to June, and pollination is accomplished by Eulaema polychroma (Euglosini). The results obtained, i.e., few visits by pollinators and increased fruit production with hand pollination, are clear evidence to demonstrate that the low fruit set (0.02 fruit/flower ratio) is a consequence of pollinator limitation, due to the pollination system: 'mimicry based on naivete' The results of the experiment set to demonstrate if ants were functioning as plant-guards against herbivores, mainly Stethobaris sp. (Curculionidae), follow four clear tendencies: (1) ant presence is not synonymous with benefit to the plant; (2) lowest fruit production and highest inflorescence damage are significantly associated with the control (no ants) and the smaller ants (C. brevispinosa and C. planatus), and these interactions are of an antagonistic nature; (3) maximum fruit production and minimum inflorescence damage are significantly associated with the larger ant species (C. rectangularis and E. tuberculatum), and these interactions are clearly mutualistic; and (4) The increase in ant size tends to have a positive effect on the plant's reproductive output (higher fruit set) The results of the nutrient uptake experiment are compelling evidence for uptake, translocation and incorporation of nutrients from exogenously provided organic material they further demonstrate that the organic debris deposited by the ants on the internal surface of the orchid pseudobulbs are incorporated by the plant in the manner of a reversed animal-plant interaction (mutualism). These exogenous nutrients would help the plant to survive on the nutrient-poor dune soils / acase@tulane.edu

Free-living amoebae were analyzed by gas chromatography/mass spectrometry for ester-linked phospholipid fatty acids (PLFA) and sterols. Acanthamoebae, Hartmannella, and Naegleria could be classified by phospholipid composition at the genus and species levels. Major PLFAs for Acanthamoebae consisted of 18:0, 18:1s, 18:2s, and 20 carbon polyenoics at 5%, 56%, 4%, and 18% of total PLFA, respectively. Hartmannella PLFAs were 16:1s, 18:1s, 16:0, and 18:2w6 at 37%, 39%, 13% and 3%, respectively. Naegleria PLFAs were composed of long-chain 26- and 28- carbon fatty acids, 16:1s, 17:1s, and 18:1w at 10%, 15%, 19%, and 20%, respectively. Sterol compositions separated the free-living amoebae at the genus level. Ergosterol and 7-dehydroporiferasterol were the major sterols of Acanthamoebae. Hartmannella sterols were stigmasta-7,22-dienol, stigmastanol, and stigmast-7-enol. Major sterols for Naegleria were ergosterol and ergosta-5,7-dienol. / Samples of Legionella, axenically-grown Naegleria, Legionella-infected Naegleria, and infected Naegleria cured by treatment with gentamycin were analyzed for PLFA, sterols, phospholipid classes, and unextractable, covalently-bonded hydroxy fatty acids found in the lipopolysaccharide (LPS-OHFA). Legionella biomarkers were two uncommon branched monoenoic PLFAs (i16:1, a17:1) and LPS-OHFA (3OH-i14:0; 3OH-n14:0; 2,3DIOH-i14:0; 2,3DIOH-a14:0). Legionella biomarkers were observed in both trophozoite and cyst forms of the infected amoebae. These biomarkers were not detected in axenically-grown amoebae or in gentamycin-cured amoebae. Legionella infection caused shifts in Naegleria PLFAs and sterols. Increased concentrations were seen in saturated 16- and 18-carbon fatty acids as well as in cholesterol. Decreased concentrations were seen in polyenoic fatty acids, ergosterol and ergosta-5,7-dienol. These results demonstrated that the PLFA and sterol contents of Naegleria changed during bacterial infection and returned to normal with drug therapy. / When PLFA profiles of Legionella-contaminated water samples were analyzed, these profiles demonstrated distinct clustering between Legionella and the infected Naegleria. This study utilized lipid techniques to characterize free-living amoebae and a bacterial-amoebae association. The results not only defined taxonomic differences among amoebae but also provided a means to detect bacterial infections of amoebae. / Source: Dissertation Abstracts International, Volume: 52-10, Section: B, page: 5094. / Major Professor: David L. Balkwill. / Thesis (Ph.D.)--The Florida State University, 1991.

This study is the first comprehensive survey of a frog assemblage in the central Amazon. Forty-three species of frog were found in a 2,000 hectare tract of primary forest near Manaus, Brazil. Breeding habitat affiliation, breeding phenology, spatial distribution, and relative abundance were determined for most species principally by counting calling males along variable-width strip transects. Frogs were also censused with visual detection methods and in litter plots. However, these techniques were not as powerful as audio transects for assessing species composition, habitat occupancy, and abundances throughout a large area. Anuran species and generic richnesses are similar throughout the Amazon except for Eleutherodactylus which is depauperate in the central and lower Amazon. As many species were abundant in the study area as were rare. The distribution of breeding habitat abundance parallels the distribution of species-abundance and so breeding habitat availability seems the best candidate to explain the relative abundances of species in the study area. / There is pervasive correlation between life history variables, particularly reproductive mode and habitat affiliation, and phylogeny in tropical forest anurans. This association supports a hypothesis that, at a regional scale, the history of an area's colonization and speciation rates of the colonists influenced the distribution of habitat use by frogs in forest assemblages more than selection. / Litter plot sampling was biased in favour of conspicuously behaving litter species. Since the proportion of the litter fauna that is conspicuously behaving is much lower in southeast Asia than the Neotropics, there is no evidence that litter frogs per se are more abundant in the Neotropics. However, abundances of conspicuously behaving species are higher in the Neotropics. Practically all abundant species at Manaus undergo terrestrial development. It appears that terrestrial reproduction releases frog populations from dependence on limited aquatic habitat. Since two prominent Neotropical families of litter frog reproduce terrestrially whereas terrestrial development is not associated with any southeast Asian taxon, the historical colonization of these regions by different lineages explains inter-regional abundance differences most parsimoniously. / Source: Dissertation Abstracts International, Volume: 52-04, Section: B, page: 1904. / Major Professor: Daniel Simberloff. / Thesis (Ph.D.)--The Florida State University, 1991.

Advantages and disadvantages of various radioisotopic methods for measuring bacterial production are reviewed. To unraval the problems of each method, a new technique for measuring bacterial phospholipid-phosphorus (PL-P) production using $\sp{32}$P was developed. The major findings in developing the PL-P method are that: (1) specific activity of the phospholipids is the same as that of the medium, indicating that $\sp{32}$P is incorporated into PL-P at the same rate as the phosphorus in the medium, and (2) the labeling pattern of $\sp{32}$P into the phospholipids follows the macromolecular labeling pattern. / Bacterial production in the hydrocarbon seep area on the Louisiana slope, measured by the PL-P method, was strikingly high with the range from 0.03 to 1.16 g C m$\sp{-3}$ per generation. The methanotrophic or methylotrophic bacterial production related to methane and other hydrocarbon seepage seem to be a major contributing factor for the high bacterial production. Pulse-labeling experiments using size fractionation showed that bacterial growth and relative biomass were associated with particles larger than 64 $\mu$m in the hydrocarbon seep. The large and metabolically active bacterial aggregates suggest that the aggregates may serve as a trophic intermediate between bacterial carbon and seep heterotrophic benthic fauna. / Unrelated to the previous topics, the microbial aspect of polonium-210 solubilization from phosphogypsum, was also studied. Polonium-210, the last $\alpha$ emitting radionuclide in the natural uranium-238 decay series, is toxic when ingested or inhaled. Several laboratory column experiments demonstrated that polonium release in the phosphogypsum was clearly related to the bacterial activity. Sulfate reducing bacteria (SRB) play a significant role in the Po release. However, the accumulation of sulfide caused by the respiration of SRB removed the released Po by forming metal sulfide co-precipitation. Nutrient depletion in the ground water causes a decline of bacterial activity, and therefore the Po release in the ground water is probably controlled by nutrient availability affecting bacterial growth. / Source: Dissertation Abstracts International, Volume: 55-11, Section: B, page: 4736. / Major Professor: Paul A. LaRock. / Thesis (Ph.D.)--The Florida State University, 1994.

Nutrient mitigation capacity of low-grade weirs in agricultural drainage ditches

<p> River-associated birds may be valuable indicators of environmental change in riverine ecosystems because they are predators of fishes and therefore often top predators in the aquatic food web. To evaluate the likely scope of one form of change - river restoration through dam removal and the expected return of abundant diadromous fish prey - we: 1) developed an appropriate river bird survey protocol; 2) documented the relative importance of sea-run fish in the diet of four river bird species, bald eagle (<i>Haliaeetus leucocephalus</i>), osprey (<i>Pandion haliaetus</i>), belted kingfisher (<i>Megaceryle alcyon</i>), and tree swallow (<i> Tachycineta bicolor</i>); 3) documented nest distribution and brood size of osprey; and 4) investigated the relationships between river bird abundance and various habitat parameters. We expect these measures will reflect changes to the river system post-dam removal as diadromous fish populations recover, proliferate, and integrate into the food web. Based on species accumulation curves and first-order Jacknifes, we concluded that biweekly or triweekly I5 minute surveys are sufficient to meet our objectives. Within the Penobscot River, stable isotope analysis of river bird diets indicated that marine nutrients are consumed by bald eagle, osprey, and belted kingfishers that reside below the lowermost dam, but not tree swallows. Despite greater connectivity for and abundance of spawning diadromous fishes (particularly river herring), in the Kennebec and Sebasticook Rivers as compare to the Penobscot River, osprey brood size was not significantly larger. We suspect other factors such as competition with bald eagles may be limiting the benefit of large river herring runs to nesting osprey. Finally, an ordination of 26 river bird species and 5 single-species (invertivore - spotted sandpiper, piscivore - osprey; piscivore - bald eagle; insectivore - tree Swallow; and omnivore - American black duck) generalized linear models, I revealed associations between estimated species abundance and water flow, water level, distance from the river mouth (river kilometer), site position in relation to a dam (e.g. above, below, or not at a dam), and adjacent land cover composition.</p>

Although twin-spotted rattlesnakes (Crotalus pricei ) were first identified more than a century ago, little has been published about the ecology of this species and no information has been available regarding population characteristics. During 1997--99, I captured, measured, and marked 117 C. pricei in the Chiricahua Mountains to address this need for information. Lizards constituted the bulk of C. pricei prey, but their diet also included mammals, birds, and snakes. Mating and parturition were concentrated in August and early September. Movement patterns varied dramatically from year to year, as males moved substantially farther during the 1998 monsoon season (July--September) than in 1997. Crotalus pricei are sometimes collected illegally for the pet trade. About 90 people may have hunted for C. pricei at a well-known site during 1997--98. On average, snakes at this site were 38.1 mm smaller than snakes at other sites, an observation that could be attributed to collecting pressure.

The southernmost known North American stand of corkbark fir ( Abies lasiocarpa var. arizonica (Merriam) Lemm.) is found in the Santa Catalina Mountains just north of Tucson, Arizona. Climate response, age distribution, and fire history were studied in this small corkbark fir stand to provide baseline information for future management. Response function analysis indicated April--June precipitation from the current growing season, April--June temperature from the current growing season, November--March precipitation prior to the growing season, and August--October precipitation from the previous growing season as the most highly correlated factor with ring-width variance. Age distribution appeared to be steady state. A fire chronology developed for the corkbark fir site was used to test synchroneity of fire events with previously developed chronologies from nearby sites. Chi-squared analyses indicated significant association of fire years for all sites but not spread of fire from one site to another.

I investigated patterns of genetic variation in the North American gall-forming aphid, Pemphigus obesinymphae. In Chapters 2a and 2b, I developed and then implemented clone-specific molecular markers to investigate clonal mixing in P. obesinymphae . During its gall-forming phase, P. obesinymphae clones produce aggressive larval "soldiers", which altruistically defend their colonies from natural enemies. I showed that movement occurs between galls, indicating that P. obesinymphae colonies are not pure clones. I also showed that intruders behave selfishly, by not defending unrelated clones, and by accelerating development into reproductive adults. These results reveal a greater degree of complexity and conflict in aphid social groups than previously known. In Chapter 2c, I surveyed molecular variation in P. obesinymphae and its bacterial endosymbiont, Buchnera aphidicola. I found levels of variation at two Buchnera loci to be similar to those estimated from a previous study on a distantly-related aphid, Uroleucon ambrosiae. In the western US, P. obesinymphae and B. aphidicola were nearly monomorphic, and in the eastern US, estimates of synonymous divergence ranged from 0.08 to 0.16%. Most polymorphisms in sub-populations at low frequencies, indicating a recent purge of ancestral polymorphism. These results emphasize the importance of aphid population biology in shaping evolutionary patterns in B. aphidicola. In Chapter 2d, I explored the role of life cycle variation in speciation between Pemphigus aphids. P. obesinymphae and P. populi-transversus are closely-related and sympatric on the cottonwood, Populus deltoides (Salicaceae), but they have distinctly different life cycles. P. populi-transversus has a sexual stage that occurs in the fall, while P. obesinymphae produces sexuales in late spring. Field evidence indicates that intermediate phenotypes rarely occur, and mitochondrial and bacterial endosymbiont DNA sequences show no maternal gene flow between the two species. I considered the possibility of an initial allopatric phase in the divergence, and discuss the sequence of evolutionary changes that likely led to the sympatric divergence of P. populi-transversus and P. obesinymphae. The most plausible interpretation of available data is that a shift in timing of the life cycle in an ancestral population spurred divergence between the species pair.

This dissertation investigated the evolution and ecology of male sterility in the gynodioecious Bouteloua chondrosioides (Poaceae) by studying the distribution, inheritance, phenotypes of male sterility, mitochondrial DNA polymorphisms, and the distribution and effect polyploidy has on sex type expression in B. chondrosioides. B. chondrosioides has two male sterile types, one of which is described for the first time in this dissertation. Field studies determined that the proportion of male sterility was highly variable among populations and non-randomly distributed within populations. Investigations of the progeny of individuals of known sex type rejected models of simple nuclear recessive and dominant inheritance of male sterility. Examination of characters that may affect reproduction demonstrated that there were few significant reproductive differences explaining the maintenance of the two male sterile forms. In order to investigate if male sterility is due to cytoplasmic factors, mitochondrial DNA restriction fragment length polymorphisms were examined to determine if there were correlations between unique restriction fragment patterns and male sterile forms. These studies demonstrated that some, but not all, male sterile individuals do have unique mitochondrial restriction fragments. In addition to these investigations, the distribution of polyploidy was characterized and investigations performed to determine if there are correlations between sex type and ploidy level and if polyploidy has evolved once or multiple times in B. chondrosioides. Flow cytometry resulted in data that demonstrated no correlation between male sterility and ploidy level, and that while most populations are either only diploid or tetraploid, some populations had both diploid and polyploid individuals. The examination of the relationships of cpDNA sequences from individuals of known ploidy level demonstrated that polyploidy appears to have originated and established more than once in the history of B. chondrosioides. The results from these three studies exhibit patterns that are in accord with the hypothesis that male sterility in B. chondrosioides is due to cytoplasmic male sterility.