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Resource allocation to vegetative versus reproductive structures in Piper sp

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Title:
Resource allocation to vegetative versus reproductive structures in Piper sp
Translated Title:
La asignación de recursos a los crecimientos vegetativos frente a los crecimientos reproductivos en Piper sp ( )
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English
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Martinko, Melissa, M
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Plants--Reproduction   ( lcsh )
Plant anatomy   ( lcsh )
Costa Rica--Puntarenas--Monteverde Zone--San Luis   ( lcsh )
Plantas--Reproducción
Anatomía vegetal
Costa Rica--Puntarenas--Zona de Monteverde--San Luis
Tropical Ecology Fall 2009
Ecología Tropical Otoño 2009
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Reports   ( lcsh )
Reports

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Abstract:
Resource allocation theory in plants dictates that resources utilized for one physiological process are unavailable for another, and that plants must selectively allocate critical resources in order to maximize their fitness. Therefore, resources allocated to reproductive growth are unavailable for vegetative growth and vice versa. The relationship between vegetative and reproductive growth was examined for a common Piper species found in San Luis, Monteverde, Costa Rica by comparing the size of leaves with opposing inflorescences on the same node to the size of leaves without opposing inflorescences on the same node. A total of 18 Piper plants with mature inflorescences were sampled, eight in forest edge locations and ten in forest understory locations. There was no difference in average length (t = -0.695, df = 358, P = 0.4877) or average width (t = 0.271, df = 358, P = 0.7864) between leaves with opposing inflorescences and leaves without opposing inflorescences. Thus, resource allocation to reproduction did not translate into a reduction in vegetative production of leaves in Piper sp. Alternatively, diversion of resources to reproduction may manifest itself as a reduction in other vegetative structures such as roots or stems, or as a reduction in other plant processes such as herbivore and pathogen defense.
Abstract:
La teoría de la repartición de recursos en las plantas dicta que los recursos utilizados para un proceso fisiológico no están disponibles para otro, y que las plantas tienen que repartir los recursos críticos selectivamente para maximizar su aptitud. Por lo tanto, los recursos repartidos para el crecimiento reproductivo no están disponibles para el crecimiento vegetativo y viceversa. Se examinó la relación entre el crecimiento vegetativo y el crecimiento reproductivo para una especie común de Piper que se encuentra en San Luis, Monteverde, Costa Rica por comparación entre el tamaño de las hojas con inflorescencias opuestos en el mismo nódulo con el tamaño de las hojas sin inflorescencias opuestos en el mismo nódulo. Se midió un total de 18 plantas de Piper sp. con inflorescencias maduros, ocho en sitios de sotobosque del bosque y diez en sitios del borde del bosque. No había una diferencia en los largos medios (t = -0.695, df = 358, P = 0.4877) o los anchos medios (t = 0.271, df = 358, P = 0.7864) entre las hojas con inflorescencias opuestas y las hojas sin inflorescencias opuestas. Los resultados indican que la repartición de los recursos para la reproducción no se tradujo en la reducción de la producción vegetativa de las hojas de Piper sp. Como alternativa, la diversión de los recursos para la reproducción puede manifestarse como la reducción de otras estructuras vegetativas (e.g., las raíces, los tallos), o como una reducción en otros procesos de las plantas (e.g., defensa contra herbívoros y patógenos).
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Text in English.
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1 Resource allocation to vegetative versus reproductive structures in Piper sp. Melissa M. Martinko Department of Biology, University of New Hampshire ABSTRACT Resource allocation theory in plants dictates that resources utilized for one physiological p rocess are unavailable for another, and that plants must selectively allocate critical resources in order to maximize their fitness. Therefore, resourc es allocated to reproductive growth are unavailable for vegetative growth and vice versa. The relations hip between vegetative and reproductive growth was examined for a common Piper species found in San Luis, Monteverde, Costa Rica by comparing the size of leaves with opposing inflorescences on the same node to the size of leaves without opposing infloresce nces on the same node. A total of 18 Piper plants with mature inflorescences were sampled, eight in forest edge locations and ten in forest understory locations. There was no difference in average length ( t = 0.695, df = 358, P = 0.4877) or average widt h ( t = 0.271, df = 358, P = 0.7864) between leaves with opposing inflorescences and leaves without opposing inflorescences. Thus, resource allocation to reproduction did not translate into a reduction in vegetative production of leaves in Piper sp. Alter natively, diversion of resources to reproduction may manifest itself as a reduction in other vegetative structures such as roots or stems, or as a reduction in other plant processes such as herbivore and pathogen defense. RESUMEN La teora de l a reparticin de recursos en las plantas dicta que los recursos utilizados para un proceso fisiolgica no estn disponible para otro, y que las plantas tienen que repartir los recursos crticos selectivamente para maximizar su fitness. Por lo tanto, los r ecursos repartidos para el crecimiento reproductivo no estn disponible para el crecimiento vegetativo y viceversa. Se examin la relacin entre el crecimiento vegetativo y el crecimiento reproductivo para un especie comn de Piper que se encuentra en San Luis, Monteverde, Costa Rica por comparacin entre el tamao de las hojas con inflorescencias opuestos en el mismo ndulo con el tamao de las hojas sin inflorescencias opuestos en el mismo ndulo. Se medi un total de 18 plantas de Piper sp. con inflore scencias maduros, ocho en sitios de sotobosque del bosque y diez en sitios del borde del bosque. No haba una diferencia en los largos medios ( t = 0.695, df = 358, P = 0.4877) o los anchos medios ( t = 0.271, df = 358, P = 0.7864) entre las hojas con infl orescencias opuestas y las hojas sin inflorescencias opuestas. Los resultados indican que la reparticin de los recursos para la reproduccin no se traduci en la reduccin de l a producin vegetativo de las hojas de Piper sp. Como alternativo, la divers in de los recursos para la reproduccin puede manifestarse como la reduccin de ortos estructuras vegetativos (e.g., los races, los tallos), o como una reduccin en otros procesos de las plantas ( e.g., defensa contra herbvoros y patogenos). A LL PLANTS REQUIRE A CERTAIN SE T OF RESOURCES in order to support their wide array of physiological processes (Herms & Mattson 1991). Most of these resources, including carbon, water and nutrients, must be drawn from the surrounding environment (Bloom et al 1985). Once a plant acquires any resource from the environment, it must decide what to do with that resource: The plant can either store the resource internally for later use, or use the resource immediately in the production of various structures, including ve getative structures such as leaves, stems and roots (Bloom et al 1985); reproductive structures such as flowers, fruits, and seeds (Reekie & Bazzaz 1987); and defensive structures such as thorns, spines and secondary chemical compounds (Herms & Mattson 19 91). What a plant does with a given resource depends upon many factors, including the current climactic state and the relative abundances of different limiting resources in the environment (Bloom et al. 1985). This

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2 concept of a finite supply of resources available to a plant, which necessitates the selective allotment of resources to different activities, is referred to as resource allocation theory. The central discussion of resource allocation theory in plants has concerned the division of resources between vegetative and reproductive functions (Herms & Mattson 1991). The purpose of vegetative growth has been designated as the accumulation of resources; thus vegetative structures include all plant parts directly involved in resource capture, includin g the leaves and the root and stem material required to support them (Reekie & Bazzaz 1987). The purpose of reproductive growth has been defined as an increase in current levels of reproduction, and thus includes flowers and seeds and their associated pro tective structures (Reekie & Bazzaz 1987). Resource allocation theory assumes that vegetative and reproductive growth compete for the same resources within a plant, such that an increase in either activity results in a decrease in the other (Reekie & Bazz az 1987). Thus, there exists a trade off between resources allocated to growth and resources allocated to reproduction (Herms & Mattson 1991). Several studies have sought to elucidate the mechanism by which plants allocate their resources between vegeta tive and reproductive function; however, the results of these studies have not been consistent. Some studies have shown evidence of a decrease in vegetative growth that occurs simultaneously with an increase in reproductive growth (Homlsgaard 1955, Gross 1972, Harper & White 1974, Piero et al 1982, Luken 1987). For example, a study in Ontario, Canada documented a reduction in crown foliage of the birch tree species Betula alleghaniensis and B. papyrifera during times of high seed production (Gross 1972) Nonetheless, other studies do not confirm the traditional predictions of resource allocation theory (Reekie & Bazzaz 1987, Herms & Mattson 1991). Yasumura et al. (2006) found that there was no difference in leaf growth for the tree species Fagus crenat a between reproductive mast years and intervening non mast years in a forest in Northeast Japan. Therefore, a reduction in vegetative growth may not be a universal feature of plant reproduction. This study examines the relationship between vegetative and reproductive growth in Piper sp. and thus searches for the presence of resource allocation. According to resource allocation theory, any resources that Piper sp. allocates to the vegetative production of leaves will be unavailable for the reproductive pr oduction of inflorescences, and vice versa. Thus this study predicts that in Piper sp., where a single branch node possesses both an inflorescence and a leaf, the presence of the inflorescence should translate into reduced dimensions of the adjacent leaf, when compared to leaves that are not adjacent to inflorescences. METHODS S TUDY S ITE This study was conducted in San Luis, Monteverde, Costa Rica. San Luis is located on the Pacific slope of Costa Rica, approximately 1000 meters above sea lev el (Timm & LaVal 2000). Data were collected over a ten day period from November 5 to November 14, 2009. During this time, occurs between the traditional wet and dry seasons in the San Luis area. The transition season begins in November and lasts until January, and is characterized by strong northeasterly trade winds and primarily wind driven precipitation and mist (Clark et al 2000). Both forest unders tory and forest edge locations were considered in this study. The forest understory locations were located along Camino Real, a trail maintained by the Ecolodge San Luis at the University of Georgia Costa Rica Campus. The forest edge locations were locate d alongside a dirt road running from the Ecolodge San Luis toward the San Luis waterfall.

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3 S TUDY S PECIES This study investigated one species of the plant genus Piper (Piperaceae). The Piper genus is pantropical, with the majority of the five hundred sp ecies found in the New World tropics (Burger 1972). Piper plants are common members of the tropical forest understory, and can have growth forms ranging from small herbaceous plants to small trees (Burger 1972). Most are small shrubs between one and thre e meters tall (Burger 1972), a description fitting the species utilized in this study. All Piper species have solitary spike inflorescences containing small, densely packed flowers (Fleming 1983). The inflorescences are leaf opposed (Fleming 1983), meani ng that any inflorescence emerging on a branch is located on a node from whence a leaf also emerges in the opposite direction. This property allows the quantification of vegetative versus reproductive resource allocation in Piper species, via comparison o f leaves having an opposing inflorescence with leaves lacking an opposing inflorescence. Since differences in leaf size were used as a measure of vegetative growth and leaves are directly involved in the capture of carbon dioxide from the environment, car of allocation implicit in this study (Reekie & Bazzaz 1987). D ATA C OLLECTION Eighteen plants of one species of Piper were selected for this study. Eight plants were located in forest edge locations and ten plants were located in forest understory locations, as described above. Only reproductive plants with mature inflorescences were considered, as this allowed comparison of vegetative and reproductive allocation both within an individual plant and between all plants sampled. Inflorescences were distinguished from infructescences using a 14x hand lens. Infructescences were not considered in this study in order to eliminate any variation they might introduce. For each plant selected, the lengths and widths of ten leaves wit h opposing inflorescences and ten leaves without opposing inflorescences were measured to the nearest hundredth of a centimeter using a caliper (Best Value Steel Caliper, H420226). Thus, a total of 360 leaves were sampled. To ensure consistency across me asurements, length was measured from the tip of the leaf to the lowest point of the asymmetrical leaf base, and width was measured at the widest point of each leaf. All leaves were selected from the same range of branch heights (120 to 150 cm) to control for the effects of leaf location on the plant. Additionally, all leaves were located on the second node from the branch tip to control for the effects of leaf age. For the ten leaves per plant with opposing inflorescences, the lengths of the inflorescenc es (excluding the peduncle) were measured with a caliper (Best Value Steel Caliper, H420226) to the nearest hundredth of a centimeter. Plant height for each individual plant was also recorded to the nearest centimeter using a tape measure. S TATISTICA L A NALYSIS T tests were performed to compare the average lengths and widths of leaves with opposing inflorescences to leaves without opposing inflorescences, as well as differences in leaf size and inflorescence height between Piper plants found in fore st understory and forest edge locations (JMP Version 5.0.1a, 2002). Linear regression analyses were used to relate leaf length and leaf width to inflorescence height (JMP Version 5.0.1a, 2002). RESULTS There was no difference between the lengths of le aves with opposing inflorescences and leaves without opposing inflorescences ( t = 0.695, df = 358, P = 0.4877; Figure 1). Nor was there a difference between the widths of leaves with opposing inflorescences and leaves without opposing inflorescences ( t = 0.271, df = 358, P = 0.7864; Figure 1). Therefore, a reduction in leaf growth was not observed. Additionally, inflorescence height was not correlated with either leaf length (F 1,178 = 2.3163, P =

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4 0.1298, R 2 = 0.01285; Figure 2) or leaf width (F 1,178 = 3 .5180, P = 0.0623, R 2 = 0.01938; Figure 3). The average leaf widths and inflorescence heights were similar for Piper plants found in forest understory and forest edge locations (leaf widths: t = 1.399, df = 358, P = 0.1627; inflorescence heights: t = 1.637, df = 178, P = 0.1034; Figure 4). However, the leaf lengths of Piper plants in the forest understory were larger, on average, than the leaf lengths of Piper plants in the forest edge locations ( t = 8.776, df = 358, P < 0.0001; Figure 4). DISCUSSION This study aimed to demonstrate the differential allocation of resources between vegetative and reproductive function in Piper sp. specifically that the presence of an inflorescence would divert resources from vegetative growth and thus lead t o a reduction in leaf dimensions. However, data analysis revealed that there was no difference between either the lengths or the widths of leaves with opposing inflorescences and those without opposing inflorescences. Since no reduction in leaf size was observed, allocation to reproductive function in Piper sp. does not result in reduced allocation to vegetative growth, at least in the form of leaves. Furthermore, when leaves with opposing inflorescences were considered alone, there was no correlation be tween either leaf length or leaf width and inflorescence height. Thus, larger inflorescences, which presumably would require more allocated resources to produce, did not translate into smaller leaves. This further exemplifies that resource allocation to reproduction in Piper sp. does not cause reduced leaf growth. Several factors could explain the lack of evidence for differential resource allocation between vegetative structures and reproductive structures in Piper sp Although a decrease in leaf s ize was not observed in this study, it is possible that a reduction in the size of other vegetative structures had occurred. For example, Piper sp. stem and root growth could have been influenced by investment in inflorescences. Many studies have documen ted this occurring in other plant species. Homlsgaard (1955, in Harper and White 1974) found that the masting tree species Fagus sylvatica showed a reduction in annual ring width during years with reproductive masting events; Luken (1987) showed that see d bearing colonies of Rhus typhina also experienced a reduction in annual ring width, as well as a reduction in terminal stem length; Piero et al. (1982) found that mature palm trees of the species Astrocaryum mexicanum allocated increasing amounts of re sources to reproduction at the expense of root growth. Further studies of resource allocation in Piper sp. should consider the effects of reproduction on all types of vegetative growth, not just leaves. Moreover, a plant may not sacrifice its vegetative growth at all, and instead may divert resources from other physiological processes to facilitate reproduction. Reproduction may come at the expense of plant defensive mechanisms, meaning less carbon is available for the plant to invest in protection again st herbivores and pathogens (Herms & Mattson 1991). For instance, a decrease in the production of carbon based defensive compounds, such as phenolics and terpenoids, may be associated with an increase in the production of reproductive structures (Mattson 1980). Thus, a reduction in vegetative growth may not always be an adequate indicator of resource allocation in plant species. Since many species in the Piperaceae family are known to produce secondary compounds with anti herbivore properties ( Navickiene et al 2007), it would be interesting to examine whether the levels of these compounds in Piper leaves decrease when inflorescences are present. To investigate this possibility, future studies could either look directly for a reduction in secondary chemi cal compounds in the leaves of reproductive Piper plants, or indirectly for increased levels of herbivory in those same leaves. Another factor that needs to be taken into consideration is the plant's capacity to compensate for

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5 the carbon costs of reproduction through reproductive photosynthesis. More specifically, the ability of reproductive structures to supply some of their own carbon may lead to less diversion of resources from other plant functions (Reekie & Bazzaz 1987). For example, Reekie and Bazzaz (1987) found that the reproductive plants of Agropyron regens experienced an increase in overall photosynthetic rate, which they attributed partly to photosynthesis occurring within reproductive structures themselves ( i.e. the inflorescences a nd culms). Additionally, in Rhus typhina plants studied by Luken (1987), the developing fruits were green and capable of photosynthesis; carbon fixation occurring within the fruits may have helped compensate for the carbon requirements of seed production. This could be the case for the Piper species used in this study, as immature inflorescences were also green and possibly photosynthetic. Therefore, if reproductive structures in certain plants are able to supplement their own resource requirements, a la rge reduction in vegetative growth need not occur. A final factor to consider with any study of resource allocation is that it is not clear which vegetative or reproductive growth (Bloom et al 1985). Many studies, including the present one, have assigned this role to carbon, and have focused upon differences in the growth of different plant structures to determine patterns of resource allocation (Watson 198 4). However other critical resources, such as water or nutrients like nitrogen and phosphorus, may be more important than carbon in the environments where they are limiting (Bloom et al 1985). Therefore, in order for resource allocation studies to be va lid, they must measure costs in relation to the true limiting resource (Watson 1984). If carbon is not the limiting resource for Piper plants in San Luis, then changes in vegetative growth would not be an indicator of resource allocation. Data analysis d id reveal that average leaf lengths were longer for Piper plants in the forest understory than for Piper plants in the forest edge locations. This difference in leaf length may be explained by differences in daily light levels between the two locations. Understory habitats are characterized by lower light levels due to shading by canopy trees, receiving less than one percent of full sunlight on average (Rundel & Gibson 1996). Furthermore, light in the understory is both spatially and temporally variable t the understory, and these sunflecks are important for temporarily enhancing photosynthetic rates in understory plants (Rundel & Gibson 1996). These low and inconsistent light l evels cause many understory species to invest in the production of larger leaves, in order to both harvest as much sunlight as possible and to increase the likelihood of intercepting a sunfleck (Rundel &Gibson 1996). Therefore, the Piper plants in the for est understory may produce larger leaves in order to maximize light capture; Piper plants along the forest edge can maintain smaller leaves, as sunlight is more direct and consistent in this exposed location. This result suggests that light levels are mor e important in determining leaf size in Piper sp. than is the diversion of resources for reproduction. This study only considered differential resource allocation to leaves within a single plant. Thus, it is possible that the non reproductive Piper pla nts that were not considered in this study exhibited a different resource allocation pattern than the reproductive Piper plants. Future studies could look at both reproductive plants and non reproductive plants to see if there is a difference in leaf size between plants that are investing resources into reproduction and plants that are investing resources only into vegetative growth. If non reproductive plants had larger leaves on average, this could be one line of evidence in support of differential resou rce allocation. Another limitation of this study was the short time scale of data collection; perhaps if changes in individual plants were tracked between reproductive and vegetative states, long term allocation patterns would be elucidated. For example Harper and White (1974) state that for Mangifera indica a large fruit crop results in lower production of vegetative shoots in the same year; this reduction in shoot production might have been overlooked if the study did not extend throughout the year. Patterns of

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6 resource allocation can even emerge suprannually; in the study by Homlsgaard (1955, in Harper and White 1974), F. sylvatica experienced a decrement in annual ring width for two years after a reproductive masting event, signifying the need to r eplenish the carbon stores that had been used to foster reproduction during the masting event. Thus, longer term studies of resource allocation would be useful to highlight patterns that are not visible in studies of short duration. ACKNOWLEDGEMENTS I thank Anjali Kumar and Alan Masters for their support during the development and evolution of this project from its original into its final form, and again I thank Anjali Kumar for visiting San Luis to help initiate data collection. I thank Yimen Araya and Jos Carlos Caldern for their facilitation of the field work required for this study by supplying all the equipment required. I thank the Ecolodge San Luis for the generous use of their trails system. Lastly, I thank the Picado Mora family for thei r support during the entire course of this project. LITERATURE CITED B LOOM A.J., F.S. C HAPIN III, AND H.A. M OO NEY 1985. Resource limitation in plants: an economic analogy. Annual Review of Ecology and Systematics. 16: 363 392. B URGER W.C. 1971 Evolutionary trends in the Central American species of Piper (Piperaceae). Brittonia 24: 356 362. C LARK K.L., R.O. L AWTON AND P.R. B UTLER 2000. The Physical Environment. In N.M. Nadkarni and N.T. Wheelwright, eds. Monteverde: Ecology and Conservation of a Tropical Cloud Forest, pp. 18. Oxford University Press, New York, New York. F LEMING T.H 1983. Piper (Candela Candelillos, Piper). In D.H. Janzen ed. Costa Rican Natural History, pp. 303 304. The University of Chicago Press, Chicago, Illinois. G ROSS H.L 1972. Crown deterioration and reduced growth associated with excessive seed production by birch. Canadian Journal of Botany 50: 2431 2437. H ARPER J.L. A ND J. W HITE 1974. The Demography of Plants. Annual Review of Ecology and Systematics 5: 419 463. H ERMS D.A. AND W.J. M ATTSON 1991. Does reproduction compromise defense in woody plants? In: Baranchikov, Y uri N., Mattson, William J., Hain, Fred P., and Payne, Thomas L., eds. Forest Insect Guilds: Patterns of Interaction with Host Trees, pp. 35 46. U.S. Department of Agriculture, Forest Service, Gen. Tech. Rep. NE 153, Radnor, Pennsylvania. H OMLSGAARD E 1955. Tree ring analyses of Danish forest trees. Forstl. Forsoksv. Dan. 183:1 24. L UKEN J.O. 1987. Interactions between seed production and vegetative growth in staghorn sumac, Rhus typhina L. Bulletin of the Torrey Botanical Club 114: 247 251. M ATT SON W.J. 1980. Herbivory in relation to plant nitrogen content. Annual Review of Ecology and Systematics 11: 119 161. N AVICKIENE H.M.D., J.E. M IRANDA S.A. B ORTOLI M.J. K ATO V.S. B OLZANI AND M. F ULAN 2007. Toxicity of extracts and isobutyl amides f rom Piper tuberculatum : potent compounds with potential for the control of the velvetbean caterpillar, Anticarsia gemmatalis. Pest Management Science 63: 399 403. P IERO D., J. S ARUKHN AND P. A LBERDI 1982. The costs of reproduction in a tropical p alm, Astrocaryum mexicanum Journal of Ecology 70: 473 481.

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7 R EEKIE E.G. AND F.A. B AZZAZ 1987. Reproductive effort in plants. 1. Carbon allocation to reproduction. The American Naturalist. 129: 876 896. R EEKIE E.G. AND F.A. B AZZAZ 1987. Reproductive effort in plants. 3. Effect of reproduction on vegetative activity. The American Naturalist. 129: 907 919. R UNDEL P.W. AND A.C. G IBSON 1996. Adaptive strategies of growth form and physiological ecology in neotropical lowland rain forest plants. In A. C. Gibson, ed. Neotropical Biodiversity and Conservation, pp. 33 71. Mildred E. Mathias Botanical Garden, University of California, Los Angeles, Los Angeles, California. T IMM R.M. AND R.K. L A V AL 2000. Mammals. In N.M. Nadkarni and N. T. Wheelwright, ed s. Monteverde: Ecology and Conservation of a Tropical Cloud Forest, pp. 232. Oxford University Press, New York, New York. W ATSON M.A 1984. Developmental constraints: effect on population growth and patterns of resource allocation in a clonal plant. Th e American Naturalist 123: 411 426. Y ASUMURA Y., K. H IKOSAKA AND T. H IROSE 2006. Resource allocation to vegetative and reproductive growth in relation to mast seeding in Fagus crenata Forest Ecology and Management 229: 228 233.

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8 FIGURES FIGURE 1. Average lengths and widths (X SD) of Piper sp. leaves with opposing inflorescences and without opposing inflorescences in San Luis, Monteverde, Costa Rica. Each average was based on N = 180 leaves. No si gnificant difference was seen between the averages in the two groups. FIGURE 2. Influence of Piper sp. leaf length on inflorescence height in San Luis, Monteverde, Costa Rica (N = 180). No correlation was seen between these two dimensions. The dashed line represents the linear regression.

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9 FIGURE 3. Influence of Piper leaf width on inflorescence height in San Luis, Monteverde, Costa Rica (N =180). No correlation was seen between these two dimensions. The dashed line represents the linear regression. FIGURE 4. Average lengths, widths, and inflorescence heights (X SD) of Piper leaves in forest edge and forest understory locations in San Luis, Monteverde, Costa Rica. Each av erage is based on N = 180 leaves. There was no significant difference between the leaf widths or inflorescence heights in these two locations, however leaf lengths were longer in the forest understory than in the forest edge locations.


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Resource allocation theory in plants dictates that resources utilized for one physiological process are unavailable for another, and that plants must selectively allocate critical resources in order to maximize their fitness. Therefore, resources allocated to reproductive growth are unavailable for vegetative growth and vice versa. The relationship between vegetative and reproductive growth was examined for a common Piper species found in San Luis, Monteverde, Costa Rica by comparing the size of leaves with opposing inflorescences on the same node to the size of leaves without opposing
inflorescences on the same node. A total of 18 Piper plants with mature inflorescences were sampled, eight in forest edge locations and ten in forest understory locations. There was no difference in average length (t = -0.695, df = 358, P = 0.4877) or average width (t = 0.271, df = 358, P = 0.7864) between leaves with opposing inflorescences and leaves without opposing inflorescences. Thus, resource allocation to reproduction did not translate into a reduction in vegetative
production of leaves in Piper sp. Alternatively, diversion of resources to reproduction may manifest itself as a reduction in other vegetative structures such as roots or stems, or as a reduction in other plant processes such as herbivore and pathogen defense.
La teora de la reparticin de recursos en las plantas dicta que los recursos utilizados para un proceso fisiolgico no estn disponibles para otro, y que las plantas tienen que repartir los recursos crticos selectivamente para maximizar su aptitud. Por lo tanto, los recursos repartidos para el crecimiento reproductivo no estn disponibles para el crecimiento vegetativo y viceversa. Se examin la relacin entre el crecimiento vegetativo y el crecimiento reproductivo para una especie comn de Piper que se encuentra en San Luis, Monteverde, Costa Rica por comparacin entre el tamao de las hojas con inflorescencias opuestos en el mismo ndulo con el tamao de las hojas sin inflorescencias opuestos en el mismo ndulo. Se midi un total de 18 plantas de Piper sp. con inflorescencias maduros, ocho en sitios de sotobosque del bosque y diez en sitios del borde del bosque. No haba una diferencia en los largos medios (t = -0.695, df = 358, P = 0.4877) o los anchos medios (t = 0.271, df = 358, P = 0.7864) entre las hojas con inflorescencias opuestas y las hojas sin inflorescencias opuestas. Los resultados indican que la reparticin de los recursos para la reproduccin no se tradujo en la reduccin de la produccin vegetativa de las hojas de Piper sp. Como alternativa, la diversin de los recursos para la reproduccin puede manifestarse como la reduccin de otras estructuras vegetativas (e.g., las races, los tallos), o como una reduccin en otros procesos de las plantas (e.g., defensa contra herbvoros y patgenos).
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