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1 Population distribution and variability of mucosal-sheath mass of Calastoma cinnabarium in the Cloud Forest of Monteverde, Costa Rica Cecilia Sorensen Department of Environmental, Population and Organis m Biology, University of Colorado Tanner Scrivens Department of Environmental Science and Mathematics University of Oregon ABSTRACT Comprising an entire kingdom to themselves, fungi h ave been poorly studied relative to their diversity and importance across ecosystems. Calastoma cinnabarium is one of these widely distributed but understudie d mushrooms found throughout the Americas. The purpos e of this study was to examine its elevational distribution at Monteverde, Costa Rica and adaptive value of its distinctive mucosal-sheath to investi gate its possible role in moisture regulation. Populatio n censuses were conducted along an elevational grad ient through two life zones in the Monteverde Cloud Fore st in parallel with a study determining mucosal-she ath mass to cap size diameter. Additionally, the adapti ve value of mucosal-sheathing was examined through the removal and subsequent 16-day exposure to high elev ation environmental conditions. Population size was not significantly correlated with elevation (R2 = 0.077, p-value = 0.315, n = 15). Mucosal-sheath m ass to cap diameter ratio varied significantly between ele vations (F-value = 4.89, p-value = 0.001, df = 4, n = 128) and supported the prediction that it serves to prev ent desiccation at lower elevations. The mucosal sh eath was found to confer a fitness advantage to C. cinnabarium by helping it cope with abiotic factors such as moisture and temperature, but not for biotic condit ions, such as fungivory ( l2 = 6.15, p-value = 0.046, df = 2, n = 40). Results from this experiment reinforce the notion of high fungal environmental specificit y and shows how this constraint drives specialized morpho logy. RESUMEN Comprendiendo un reino en si mismos, los hongos han sido pobremente estudiados en relacin a su diversidad e importancia a lo largo de los ecosiste mas. Calastoma cinnabarium es uno de estos hongos ampliamente distribuidos y muy poco estudiados que se encuentra en todo el continente de Amrica. El propsito de este estudio fue examinar la distribuc in altitudinal y el valor adaptativo de la capa mu cosa de C. cinnabarium con el fin de investigar su possible papel en la r egulacin de humedad. Se condujeron censos de poblaciones a lo largo de un gradiente al titudinal a lo largo de dos zonas de vida en el bos que nuboso de Monteverde junto con otro estudio para de terminar la masa de la capa mucosa con respecto al dimetro del tamao de la copita. En forma adicion al, se examino el valor adaptativo de la capa de mu cosa por medio de la remocion de la misma y con una subs ecuente exposicion de dieciseis dias a condiciones ambientales tipicas de elevaciones altas. El tama o de la poblacion no estuvo significativamente correlacionado con la elevacion (R2 = 0.077, valor de p = 0.315, n = 15). La tasa de l a masa de la capa mucosa con respecto al diametro de la copita vario significativamente entre las elevaciones (valor de F = 4.89, valor de p = 0.001, df = 4, n = 128) y apoya la prediccin de que esta sirve para prevenir desec acin a elevaciones bajas. Se encontro que la capa mucosa c onfiere una ventaja adaptativa a C. cinnabarium ayudndole a resistir los factores abiticos tales como temperatura y humedad, pero no a resistir los factores biticos,tales como funguivorismo ( l2 = 6.15, valor de p = 0.046, df = 2, n = 40). Los resultados
2de este experimento reenforzan la nocin de una alt a especificidad ambiental de los hongos y muestra c mo esta restriccin conlleva a una morfologa especia lizada. INTRODUCTION Conservation efforts have tried to preserve tropica l ecosystems threatened by development and deforestation because of their rich biodiversity. However, these efforts have failed to acknowledge one crucial component of these rich ecosystems. Unique enough to comprise their own Kingdom, fungi are und erstudied relative to their diversity and function throughout biological communities. Thi s distinct group of eukaryotic organisms is estimated to have over 1.5 million spe cies and is found in virtually every ecological niche (Alexopoulos et al. 1996). The rol e of fungal communities within forest ecosystems is essential to the recycling of organic nutrients. By breaking down complex organic compounds, fungi replenish vital resources to nutrient-depleted tropical soils (Arora 1979). It is essential to study fungal ecolo gy and their interaction within tropical systems to assist in conservation and preservation efforts aimed at maintaining such rich biodiversity. Belonging to the division Basidiomycota, C. cinnabarium is a distinct fungus found throughout the Americas. Like most members of the fungi Kingdom, little is known about the natural history of the C. cinnabarium. It is grouped within the Order Tulostomatales, otherwise known as the stalked puf fballs, referring to the shape of their fruiting body (Knopf 1981). It is unique among clos e relatives by having a bright red fruiting body covered with a thick mucosal-sheathin g and an affinity for humid climates (Arora 1979). Little is known about the specific fu nction or adaptive significance of C. cinnabariums mucosal-sheath. Home to five life zones, the Monteverde Cloud Fores t provides a unique physical environment with an array of altitudinally-compress ed life zones. Straddling the Continental Divide in the Cordillera de Tilarn, th is area can be characterized by its steep elevational gradients that influence the regions p recipitation, temperature, and trade winds (Hartshorn 1983). High levels of rainfall and constant temperatures make the area an optimal habitat for fungal growth. With a highly documented variation of precipitation associated with elevation and season, the area prov ides a wide range of abiotic conditions for a diversity of fungal life (Clark et al. 2000). The direct contact that fungi have with their envi ronment makes them vulnerable to climatic fluctuations in humidity and temperatur e (McCracken 1995). Requiring particular ranges of abiotic factors for growth and development such as temperature, precipitation, carbon sources, and pH, fungi are di spersed throughout a wide range of microhabitats. For successful reproduction and germ ination, each species requires particular humidity levels and temperature (Arora 1 979). It has been a challenge to determine the sizeable influence for each abiotic f actor on each species because of their high environmental specificity alongside wide habit at distributions (Alexopoulos et al. 1996). In the tropical life zones of Monteverde, as moistu re and temperature levels fluctuate between regions, fungal development and c ommunity diversity are directly affected (Wales 1998). Furthermore, high levels of beta-diversity have been determined across life zones of the Monteverde Cloud Forest, i ndicating that distinct habitats support different communities of fungi (Ciocca 2000). These studies indicate high fungal
3 environment specificity within tropical life zones, which are defined by precipitation and temperature. Our study explores the distribution an d function of the mucosal-sheath of C. cinnabarium within two life zones of the Monteverde Cloud Fores t around the Estacin Biolgica Monteverde (EBM). We hypothesize that the distribution of C. cinnabarium will vary with elevation, which is a proxy for temp erature and precipitation within the Monteverde Cloud Forest. We predict that C. cinnabarium population sizes will be larger at higher elevations, where favorable precipitation and temperatures conditions exist. Additionally, previous studies of C. cinnabarium in the Monteverde area have attempted to examine the functional significance of its mucosal-sheathing (Veysey and Brown 2000). Limited by time and a small sample siz e, they found no association between individuals with removed mucosal-sheathing and fungivory or water logging. With a more detailed and long-term study of C. cinnabariums mucosal-sheathing, our study will investigate the possible adaptive functi on as a water regulating mechanism affecting the fitness of individuals within our stu dy sites. Therefore, if mucosal-sheaths are part of a water regulating mechanism to prevent desiccation, we will see thicker mucosal-sheaths at lower elevations where there is less precipitation and, conversely, if sheaths prevent water logging, we will see thicker sheaths at higher elevations. Furthermore, removal of the mucosal-sheathing will reduce the fitness of C. cinnabarium making it vulnerable to either fluctuating moisture levels or fungivory or both. If the mucosal sheath provides an increase in fitness, we predict that individuals with their sheaths removed will suffer higher levels of mortal ity compared to control individuals with their sheaths intact. METHODS Three related studies were conducted within and aro und the property boundaries of the EBM in July and August of 2006. The areas surveyed occurred on the Pacific slope and included Tropical Montane Moist and Wet Forest, as classified by the Holdridge Life Zone System. A population survey of C. cinnabarium was conducted within a 15501850 m elevational gradient along the Senderos Principal a nd Mirador and along a nearby ridgeline transect. These trails spanned the same elevational gradient, however, the ridgeline which runs north-west to south-east along the continental divide is consistently exposed to trade winds. In contrast the Senderos Pr incipal and Mirador run perpendicular to the continental divide and are partially blocked from trade winds. Fruiting bodies within one meter to either side of the trail were c ounted in the survey. Approximately equal sampling efforts were put forth along each tr ansect with time and energy. Linear regression analysis was used to examine possible co rrelations between population size and elevation. Fruiting bodies along both transects were collected for further study. Approximately twenty to forty fruiting bodies were randomly selected to represent each of five fifty-meter elevational categories between 1600 and 1850 m. No C. cinnabarium were found below 1600 m. Fruiting bodies were rins ed and massed before and after the complete removal of the mucosal sheath, and the dia meter of the spore case was
4 measured to the nearest millimeter. A mucosal mass to spore case diameter ratio was calculated for each body and an average value was d etermined for each elevational category. Utilizing a Kolmogorov-Smirnov test to a nalyze the distribution of data (Rohlf and Sokal 1969), a one-way ANOVA test was then used to determine whether significant differences in sheath mass to diameter ratio existe d between means. Furthermore, a Tukeys post-hoc pair-wise contrast was completed t o compare pairs of means to detect significant differences between each elevation. To examine the functional significance of the mucos al sheath, a gregarious cluster of C. cinnabarium at 1800 m was chosen. The population, located in a light gap on a steep trail embankment, was divided into two experi mental groups (n = 40). To one group, the mucosal sheath was mostly removed using a razor. The other group served as a control. Care was taken to ensure that each group c ontained a similar demographic distribution. After sixteen days of exposure and f requent monitoring, mortality in each group was accessed and recorded. Data were analyzed using contingency tests to detect differential survivability between the groups. RESULTS Population Distribution A total of 394 individual fruiting bodies from 15 d ifferent elevations were observed on the Sendero Principal, Mirador and ridgeline coveri ng an elevational range of 1645 to 1840 m (Fig. 1). No fruiting bodies were observed from the start of our elevational transect at 1550 m until 1645 m. The population si zes ranged from gregarious groups of up to 60 individuals (80% of populations) to isolat ed patches of three or less individuals (20% of populations). Populations were present on an array of substrates with varying slopes along the trail edges. The population size o f C. cinnabarium showed a positive trend with increasing elevation, but no significant correlation was determined between the two factors (Fig. 2; R2 = 0.077, p-value = 0.315 n = 15). Mucosal-Sheath Mass to Cap Diameter Analysis A total of 128 individual samples were collected fr om five different elevational transects for mucosal-sheath mass analysis. Using a mucosalsheath mass to cap diameter ratio for each individual within elevation zones, elevation a verages were calculated (Fig. 3). The lowest elevational transect contained the largest m ucosal-sheath mass to cap diameter (4.52 g/cm) while the highest elevational transect contained the smallest (2.73 g/cm). Each elevational groups mucosal-sheath mass to cap diameter was normally distributed about its mean (Kolmogorov-Smirnov, all p-value < 01). Further analysis showed that the elevational groups mean mucosal-sheath masses to cap diameter ratios were significantly different from each other (One-way AN OVA, F-value = 4.89, p-value = 0.001, df = 4, n = 128). Table 1 displays the rela tionship between pairs of elevational zones means, with pairs of significantly different means highlighted by plus signs (Tukeys post-hoc pair-wise contrast, p-value < 0.0 5, n = 128). The pairs of elevational groups that had significantly different mucosal-she ath mass to cap diameter ratios were
5 1600-1650 m and 1650-1700 m, 1600-1650 m and 1700-1 750 m, and 1600-1650 m and 1800-1850 m. Mucosal-Sheath Removal After a 16-day treatment on our control and experim ental groups of 20 fruiting bodies at an elevation of 1800 m on the Senderos Principal an d Mirador, mortality associated with fungivory and water regulation was witnessed (Fig 4 & 5). Of the 20 control fruiting bodies, three individuals were found dead, 12 were found alive, five were unaccounted for in the study site, and three were at the stage of spore dispersal. Of the 20 experimental individuals, seven were found dead, 14 were found a live, and one was at the stage of spore dispersal. It was also observed that after mu cosal-sheath removal, smaller individuals within the experimental group appeared to regenerate a minimal mucosal barrier. Initial statistical analysis of known survivorship and presumed mortality showed that mortality was independent of the absence of a mucos al-sheath (Fig. 4; Contingency analysis: l2 = 0.440, p-value = 0.507, df = 1, n = 40). These a ssumptions lumped the presumed dead (missing individuals) with the known dead individuals. By only utilizing two groupings, presumably dead or alive, an observe d number of unknown individuals outcomes were associated as presumably dead. Furthe r statistical analysis isolated these individuals into a third category to differentiate the number of known dead and the number of unknown fate. Mortality in this grouping was found to be significantly dependent on the absence of a mucosal-sheath (Fig 5 ; Contingency analysis: l2 = 6.15, pvalue = 0.046, df = 2, n = 40). DISCUSSION Fungi are known to have high environmental specific ity in their geographic distribution (Arora 1979). Therefore, it was hypothesized that the distribution of C. cinnabarium would be correlated with abiotic factors such as mo isture and temperature, both of which are tightly linked to elevation. In this study, pop ulation size was not significantly correlated with elevation (Fig. 2) above 1645 m. Ho wever, there was a positive trend between population size and elevation, suggesting t hat elevation may account for some, but not the all the distribution pattern observed. Below 1645 m no individuals were observed, which reinforces the notion of high funga l environmental specificity (McCracken 1995), and shows that C. cinnabarium prefers higher elevations in Tropical Montane Moist and Wet Forest. It is possible that a stronger correlation between population and elevation does actually exist. Our m ethodology was biased toward lower elevations sites due to the fact that we passed by them twice on each transect where as higher elevation sites were only viewed once, resul ting in a more thorough censusing of lower elevations. Thus the true trendline describi ng population versus elevation may have a steeper, possibly more significant slope. Fu ture censusing studies should consider the systematic bias present in this methodology. Our study sought to answer the question of whether mucosal sheaths provide a fitness advantage to C. cinnabarium by acting as a water-regulating mechanism. Initial
6 statistical analysis did not support this hypothesi s. Mortality was found to be independent of the presence or absence of mucosal sheath (Fig. 4). However, when we considered the unexplained disappearance of 25% of the individuals from our control site, we saw that mortality was significantly higher for individuals without mucosal sheaths (Fig. 5). These results suggest that the mucosal sheath confers a f itness advantage. The advantage is probably not anti-fungivory because the deaths appe ared to be due to rot. This study would benefit by repetition due to the large fracti on of unexplained disappearances in the control group. We hypothesized that the mucosal sheath regulates t he aqueous environment of the developing spores, by either preventing desicca tion in dryer habitats, or preventing water logging in moister habitats. The results from this experiment suggest that the mucus has a more crucial role in preventing desicca tion in drier environments. Calastoma cinnabarium populations occurring between 1600 and 1650 m were found to produce significantly more mucus relative to cap di ameter than populations between 1800-1850 m, 1650-1700 m and 1700-1750 m (Fig. 3). The significant variation in mucus sheath production between elevations implies that q uantity of mucus production is an environmentally-induced trait of C. cinnabarium That the fungus produces more mucus at lower elevations suggests that individuals rely more heavily on the protective qualities of the mucus at lower elevations where the dryness may lead to membrane damage and desiccation (McCracken 1995). Interestingly, we obs erved that after scraping, some individuals appeared to regenerate their sheath. I t appears that the physiological mechanisms regulating mucus production are continuo usly open to environmental signals and are quite complex. The energy invested in prod ucing and maintaining this elaborate structure suggests how valuable it may be for succe ssful reproduction. Previous studies in the Monteverde area showed that mucous-sheathed fungi have greater abundance at high elevations (Veysey and Br own 2000). Due to this observation, researchers suggest that the mucus sheathing protec ts fungi against water logging. Our study of C. cinnabarium reveals a similar positive trend between abundance and elevation. We hypothesize that mucus-sheathed fungi may compete better at higher elevations due to water regulation mechanisms confe rred in the mucosal sheath. In addition, based on the significantly greater thickn ess of the mucosal sheaths at lower elevations and the environmental inducibility of th e mucosal sheath, we hypothesize that this physiological mechanism allows mucus-sheathed fungi to extend their range into lower elevations. The presence of a mucosal-sheath is thought to be a plesiomorphic trait, suggested by fact that it is found in seven orders of fungi i n both the Ascomycete and Basidiomycete divisions (Veysey and Brown 2000). T here are no obvious similarities in the habitats occupied by fungi with sheaths, showin g there is an overarching fitness advantage conferred in the sheath that has been sel ected for on many different occasions under varying environmental conditions. Further st udies could investigate whether the inducibility of the mucosal sheath is present in th ese other orders. A possible explanation for why mucosal sheathing has evolved independently so many times is that it creates a favorable microclimate for reproduction, thus ameli orating the climatic variability in their habitats. To understand whether precipitation, temperature, o r some other abiotic factor more strongly influence the range and growth patter n of C. cinnabarium than others
7 further studies should sample different life zones with contrasting abiotic parameters in order to isolate variables. Another factor to consi der when examining the distribution of a fungus is that mycorrhizal interactions are extreme ly common, occurring in over 80% of plant species (Johnson and Raven 1996). It is unkn own whether C. cinnabarium participates in such an interaction. ACKNOWLEDGMENTS First off, we would like to thank everyone that has supported us throughout this study abroad adventur e, especially those who made this trip possible. We wo uld like to especially thank our advisor Karen Mast ers for her continued support, guidance and inspiration through this endeavor. Without her continual advic e and expertise and of course her humorous character this project would have never got off the ground. Special thanks to Tom McFarland and Camryn Penningt on for all their assistance with editing, computer problems, and always keeping it interesting at the station. You guys rock. Thanks to Carmen Rojas for sharing her insights, wealth of knowledge, and cons tant cheer. Thanks to all the coffee farmers in Monteverde for growing the delicious coffee that fu eled our bodies. LITERATURE CITED Alexopoulos, C. J., C. W. Mims, M. Blackwell. 1996. General Characteristics In Introduction to Mycology. 4ed. John Wiley & Sons, Inc., New York, pp. 28. Arora, D. 1979. Mushrooms Demystified 2nd ed. Ten Speed Press, Berkeley, pp. 4-8, 25-29, 718 -719 Ciocca, E. 2000. Fungal Species Richness on an Elev ational and Longitudinal Gradient on the Continenta l Divide. CIEE Tropical Ecology and Conservation, Spr ing. Clark, K. L., R. O. Lawton, P. R. Butler. 2000. The Physical Environment In Monteverde: Ecology & Conservation of a Tropical Cloud Forest. Nadkarni N. M., and N. T. Wheelwright eds. Oxford University Press, New York, pp. 1520. Hartshorn, G. S. 1983. Introduction to Plants, In Costa Rican Natural History. D.H. Janzen, eds. The University of Chicago Press, Chicago, pp. 141. Johnson, G., P. Raven. 1986. Biology Times/Mirror/Mosby College Publishing, St. Louis, Missouri, pp. 654. Knopf, L. 1981. National Auburn Society Field Guide to North American Mushrooms. New York, pp. 841-842. McCracken, T. 1995. Diversity of Fleshy Fungi in Ga ps and Forest. UCEAP Tropical Biology Program, Spring, 237-244. Rohlf, F, J., R. R. Sokal. 1969. Statistical Tables W. H. Freeman and Company, New York. (pp. 195) Veysey, J., A. Brown. 2000. The Adaptive Value of F ungal Mucous-Sheaths. Dartmouth Studies In Tropical Biology (Dartmouth College), Hanover NH, p p. 54-58. Wales, M. 1998. Fungal Abundance, Species Richness, and Diversity of Five Life Zones of Monteverde During Two Seasons. UCEAP Tropical Biology Program, Fall, pp. 1-6
8FIGURES AND TABLES nr nrn FIGURE 1. The distribution of C. cinnabarium along an elevational gradient on both the S. Principal/Mirador (diamonds ) and ridgeline (squares) trails around the EBM. nr FIGURE 2. The positive trend between Calastoma cinnabarium population size and elevation (m) between 1550-1850 meters aro und the EBM. There was no significant correlation between elevation an d population size for the observed groups (R2 = 0.077, p-value = 0.315 n = 15).
9 n FIGURE 3 Shows the average mucosal-sheath mass to cap diamet er ratio (g/cm) for each elevational transect within the Lif e Zones around the EBM. A significant difference in mucosal-sheath mas s to cap diameter ratio between three of the elevational zones existe d (refer to Table 1 & 2) (One-Way ANOVA: F-value = 4.89, p-value = 0.001, df = 4, n = 128). !"n !!"n n #$n!%%" &'r"!() FIGURE 4. Shows the mortality and survivorship between the co ntrol and experimental groups in the mucosal-sheath remov al test site at 1800 meters. The frequency of mortality was independent of the presence or absence of a mucosal-sheath (Contingency Analysis: l2 = 0.440, p-value = 0.507, df = 1,n = 40).
10 !"n !!"n n #$n!%%" #$&') # *+', FIGURE 5. Shows the mortality, survivorship, and isolated unk nown outcome condition between the control and experimen tal groups in the mucosal-sheath removal test site at 1800 meters. Th e frequency of mortality was dependent on the presence or absence of a mucosal-sheath (Contingency Analysis: l2 = 6.154, p-value = 0.0461, df = 2, n = 40). TABLE 1. Shows the significant results between average muco salsheath mass to cap diameter ratio (g/cm) for each e levational transect. Positive values show pairs of means that are signif icantly different (Tukeys Post-Hoc Pairwise Contrast: p-value = 0.05 n = 128). Elevation 1600-1650 1650-1700 1700-1750 1750-1800 1800-1850 1600-1650 + + + 1650-1700 1700-1750 1750-1800 1800-1850
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Distribucin de la poblacin y la variabilidad de la capa mucosa de Calastoma cinnabarium en el Bosque Nuboso de Monteverde, Costa Rica
Population distribution and variability of mucosal-sheath mass of Calastoma cinnabarium in the Cloud Forest of Monteverde, Costa Rica
Comprising an entire kingdom to themselves, fungi have been poorly studied relative to their diversity and importance across ecosystems. Calastoma cinnabarium is one of these widely distributed but understudied mushrooms found throughout the Americas. The purpose of this study was to examine its elevational distribution at Monteverde, Costa Rica and adaptive value of its distinctive mucosal-sheath to investigate its possible role in moisture regulation. Population censuses were conducted along an elevational gradient through two life zones in the Monteverde Cloud Forest in parallel with a study determining mucosal-sheath mass to cap size diameter. Additionally, the adaptive value of mucosal-sheathing was examined through the removal and subsequent 16-day exposure to high elevation environmental conditions. Population size was not significantly correlated with elevation (R2 = 0.077, p-value = 0.315, n = 15). Mucosal-sheath mass to cap diameter ratio varied significantly between elevations (F-value = 4.89, p-value = 0.001, df = 4, n = 128) and supported the prediction that it serves to prevent desiccation at lower elevations. The mucosal sheath was found to confer a fitness advantage to C. cinnabarium by helping it cope with abiotic factors such as moisture and temperature, but not for biotic conditions, such as fungivory (2 = 6.15, p-value = 0.046, df = 2, n = 40). Results from this experiment reinforce the notion of high fungal environmental specificity and shows how this constraint drives specialized morphology.
Comprendiendo un reino en si mismos, los hongos han sido poco estudiados en relacin a su diversidad e importancia a lo largo de los ecosistemas. Calastoma cinnabarium es uno de estos hongos ampliamente distribuidos y muy poco estudiados que se encuentran en todo el continente americano. El propsito de este estudio fue examinar la distribucin altitudinal y el valor adaptivo de la capa mucosa de C. cinnabarium con el fin de investigar su posible papel en la regulacin de la humedad.
Text in English.
Mushrooms--Morphology--Monteverde Cloud Forest Reserve (Costa Rica)
Cloud forest ecology--Costa Rica
Hongos--Morfologa--Reserva Bosque Nuboso de Monteverde (Costa Rica)
Ecologa del bosque nuboso--Costa Rica
Tropical Ecology 2006
Ecologa Tropical 2006
t Monteverde Institute : Tropical Ecology