Raymond L Tremblay | University of Puerto Rico - Humacao (original) (raw)

Papers by Raymond L Tremblay

Background/Question/Methods The distribution of orchids in the epiphytic or lithophytic environme... more Background/Question/Methods The distribution of orchids in the epiphytic or lithophytic environment is likely to result from a combination of factors including the interactions with other plant species. Here we tested for negative associations between bryophyte cover and early demography stages and positive associations of bryophyte cover on adult plants of , a riparian epiphytic and lithophytic tropical orchid. We also tested whether or not there was an association between the density of plants and the diversity and composition of bryophytes in our study area and whether or not the height of densest orchid aggregate within a phorophyte relative to the water line was related to the height 'moss' line across a rock substrate (indicative of flash flood disturbances). Results/Conclusions Bryophyte cover was not significantly different between phorophytes with neither high nor low orchid density when all plant stages were pooled nor when only the density of adult plants was cons...

PLOS ONE, 2015

The current live vaccinia virus vaccine used in the prevention of smallpox is contraindicated for... more The current live vaccinia virus vaccine used in the prevention of smallpox is contraindicated for millions of immune-compromised individuals. Although vaccination with the current smallpox vaccine produces protective immunity, it might result in mild to serious health complications for some vaccinees. Thus, there is a critical need for the production of a safe virus-free vaccine against smallpox that is available to everyone. For that reason, we investigated the impact of imiquimod and resiquimod (Toll-like receptors agonists), and the codon-usage optimization of the vaccinia virus A27L gene in the enhancement of the immune response, with intent of producing a safe, virus-free DNA vaccine coding for the A27 vaccinia virus protein. We analyzed the cellular-immune response by measuring the IFN-γ production of splenocytes by ELISPOT, the humoral-immune responses measuring total IgG and IgG2a/IgG1 ratios by ELISA, and the TH1 and TH2 cytokine profiles by ELISA, in mice immunized with our vaccine formulation. The proposed vaccine formulation enhanced the A27L vaccine-mediated production of IFN-γ on mouse spleens, and increased the humoral immunity with a TH1-biased response. Also, our vaccine induced a TH1 cytokine milieu, which is important against viral infections. These results support the efforts to find a new mechanism to enhance an immune response against smallpox, through the implementation of a safe, virus-free DNA vaccination platform.

Endangered Species Research, 2012

Lepanthes caritensis is a small epiphytic orchid endemic to Puerto Rico. Although this species is... more Lepanthes caritensis is a small epiphytic orchid endemic to Puerto Rico. Although this species is very rare and demographic studies show that its numbers are declining, it is not protected under the United States Federal Endangered Species Act (ESA). Furthermore, questions remain regarding its distribution, population size and ecological interactions, including host-specificity, which could influence its likelihood of extinction. The primary objective of this study was to document the overall population size and distribution of this orchid to determine whether it warrants federal listing. To this end, extensive surveys were conducted to document the current distribution and population size of L. caritensis. These data were used to classify the species’ rarity status according to criteria outlined by Rabinowitz, NatureServe and the IUCN. Results of these surveys indicate that the overall population of L. caritensis is larger and more widely distributed than previously thought. In addition, the species is not host-specific outside its originally described range, and is found on at least 4 different host species. Nevertheless, this species is indeed rare: it meets the criteria for the NatureServe category ‘critically imperiled’ and the IUCN category ‘Critically Endangered’. Consequently, the most important conclusion of this study is that this species warrants legal protection under the ESA, particularly if its population continues to decline.

Biodiversity and Conservation, 2010

The challenge of conservation biology is to make models that predict population dynamics and have... more The challenge of conservation biology is to make models that predict population dynamics and have a high probability of accurately tracking population change (increase, decrease, constancy). In this study we tested whether the transition model is accurate enough to predict population persistence and size 13 years down and whether after 13 years populations had achieved a stable stage distribution. We modeled 6 small populations of an epiphytic orchid using a Lefkovitch type analysis to predict population growth pattern based on monthly surveys for approximately 1.5 years. In addition, sensitivity and elasticity analyses were used to identify life stages with high sensitivity or elasticity that have the largest influence on population growth rate. We re-censused the populations 13 years after the first study and compared the structure of the populations to predictions based on the earlier census data. Effective population growth rates were similar to those expected except for one where the population went extinct. The prediction slightly (but not significantly) overestimated the actual population growth rates of some populations. Elasticity analysis revealed that the adult stage is critical in the life cycle. The observed stage distributions of the populations were not stable at the beginning of the survey and neither were they after 13 years. We suggest that this might be caused by external perturbations that result in unequal mortality between life stages and stochastic recruitment events. The ability of the matrices to predict population size approximately eight generations in the future is encouraging and warrants the continued use of these approaches for PVA.

Background and Aims Evaluation of population projection matrices (PPMs) that are focused on asymp... more Background and Aims Evaluation of population projection matrices (PPMs) that are focused on asymptotically based properties of populations is a commonly used approach to evaluate projected dynamics of managed populations. Recently, a set of tools for evaluating the properties of transient dynamics has been expanded to evaluate PPMs and to consider the dynamics of populations prior to attaining the stable-stage distribution, a state that may never be achieved in disturbed or otherwise ephemeral habitats or persistently small populations. This study re-evaluates data for a tropical orchid and examines the value of including such analyses in an integrative approach.

The science of conservation biology is the application of knowledge acquired about the biology of... more The science of conservation biology is the application of knowledge acquired about the biology of organisms to facilitate the persistence of species or control of invasive species. Habitat destruction results in population size reduction and sometimes in extinction; however, quantifying its impact is not a trivial undertaking. In many cases a minimal amount of science is needed to understand the concept that habitat destruction usually results in reduction of population size. However, if we are interested in more complex questions, such as when is habitat destruction excessive or what are the effects of habitat fragmentation and destruction, then scientific tools are required. One of the most challenging skills to be acquired is the intellectual framework to understand the interactions among individuals in a population and population-level interactions with the community. Taking a holistic approach to the scientific study of orchids in situ is more likely to result in positive conservation outcomes. In this paper we review some of the basic biological processes that affect species survival.

Orchid Science Letters, 2011

BioNews, The newsletter of the Dutch Caribbean Nature Alliance, 2013

Australasian Orchid Native Society-Victoria Chapter, 2005

Orchid Conservation, 2000

Proceedings of the 19th World Orchid Congress, Miami, 2009

Early in the history of evolutionary biology, orchids had a prominent role in providing evidence ... more Early in the history of evolutionary biology, orchids had a prominent role in providing evidence for natural selection. The unusual pollination mechanisms attracted the attention of Darwin (1877) who had argued that orchids offer strong evidence for natural selection and for the advantages of cross pollination. Since then, much effort has been devoted to describing pollination mechanisms van der Cingel, 1995). These reports contribute to Darwin's arguments, although it is not often stated explicitly. Most agree that there is a link between orchid pollination systems and orchid diversity but the distinction between cause and effect is often not clear.

Caribbean Naturalist, 2013

The distribution of orchids in the epiphytic or lithophytic environment is likely to result from ... more The distribution of orchids in the epiphytic or lithophytic environment is likely to result from the interactions with other plant species. We tested for associations between bryophyte cover and diversity and the densities of different demographic stages (seedlings and juveniles vs adults) of Lepanthes rupestris (Rock Babyboot Orchid), a riparian tropical orchid. Given that this species is predominantly lithophytic and grows near streams, we considered whether or not the location of the densest orchid aggregate within a rock substrate was also related to the location of the "bryophyte line" across the rocky substrate (a potential indicator of maximum water levels for a stream). We found that substrates with thick bryophyte covers had lower densities of early demographic plant stages relative to ones with thin covers. In contrast, higher adult densities were recorded on substrates with thick bryophyte covers relative to substrates with thin bryophyte covers. Orchid density was positively associated with bryophyte species richness, but this association is driven mostly by diversity of mosses and not by diversity of liverworts. The location of the densest L. rupestris patch within a substrate was positively related to the recorded location for the bryophyte line forming across a rock substrate. Overall results suggest that the potential interactions between bryophytes and L. rupestris are likely to be dynamic throughout the life cycle of these orchids. We discuss the potential mechanisms of these interactions (negative ones acting during early stages and positive ones acting at later stages) and the role that natural disturbance regimes along streams (i.e., flash floods) may play in the population dynamics of this species.

Endangered Species Research, 2012

Lepanthes caritensis is a small epiphytic orchid endemic to Puerto Rico. Although this species is... more Lepanthes caritensis is a small epiphytic orchid endemic to Puerto Rico. Although this species is very rare and demographic studies show that its numbers are declining, it is not protected under the United States Federal Endangered Species Act (ESA). Furthermore, questions remain regarding its distribution, population size and ecological interactions, including hostspecificity, which could influence its likelihood of extinction. The primary objective of this study was to document the overall population size and distribution of this orchid to determine whether it warrants federal listing. To this end, extensive surveys were conducted to document the current distribution and population size of L. caritensis. These data were used to classify the species' rarity status according to criteria outlined by Rabinowitz, NatureServe and the IUCN. Results of these surveys indicate that the overall population of L. caritensis is larger and more widely distributed than previously thought. In addition, the species is not host-specific outside its originally described range, and is found on at least 4 different host species. Nevertheless, this species is indeed rare: it meets the criteria for the NatureServe category 'critically imperiled' and the IUCN category 'Critically Endangered'. Consequently, the most important conclusion of this study is that this species warrants legal protection under the ESA, particularly if its population continues to decline.

Applied and Environmental Microbiology, 2012

Novel markers of fecal pollution in tropical waters are needed since conventional methods recomme... more Novel markers of fecal pollution in tropical waters are needed since conventional methods recommended for other geographical regions may not apply. To address this, the prevalence of thermotolerant coliforms, enterococci, coliphages, and enterophages was determined by culture methods across a watershed. Additionally, human-, chicken-, and cattle-specific PCR assays were used to identify potential fecal pollution sources in this watershed. An enterococcus quantitative PCR (qPCR) assay was tested and correlated with culture methods at three sites since water quality guidelines could incorporate this technique as a rapid detection method. Various rainfall events reported before sample collection at three sites were considered in the data analyses. Thermotolerant coliforms, enterococci, coliphages, and enterophages were detected across the watershed. Human-specific Bacteroides bacteria, unlike the cattle-and chicken-specific bacteria, were detected mostly at sites with the corresponding fecal impact. Enterococci were detected by qPCR as well, but positive correlations with the culture method were noted at two sites, suggesting that either technique could be used. However, no positive correlations were noted for an inland lake tested, suggesting that qPCR may not be suitable for all water bodies. Concentrations of thermotolerant coliforms and bacteriophages were consistently lower after rainfall events, pointing to a possible dilution effect. Rainfall positively correlated with enterococci detected by culturing and qPCR, but this was not the case for the inland lake. The toolbox of methods and correlations presented here could be potentially applied to assess the microbial quality of various water types.

Lankesteriana, 2011

Natural selection and genetic drift are the two processes that can lead to cladogenesis. Without ... more Natural selection and genetic drift are the two processes that can lead to cladogenesis. Without a doubt the great diversity and floral adaptation to specific pollinators are likely consequences of natural selection. Detecting natural selection in the wild requires measuring fitness advantage for specific characters. However, few published orchid studies demonstrate that floral characters are influenced by natural selection. If selection is temporal or weak, then this may explain why we rarely find selection on floral characters. Alternatively, selection on a character may not follow commonly used mathematical models that are based on linear, disruptive, and stabilizing selection and serve as null models. Moreover, fitness advantages are usually tested on general models, which assume that the parameters are normally distributed. If we forego the idea that selection follows specific mathematical models and Gaussian distribution and that all types of selection landscapes and other types of distributions (binomial, Poisson) are possible, we may discover evidence that the process of selection does play a role in explaining the great diversity of orchids. Here I show and compare the use of traditional and non-parametric approaches for measuring selection of floral characters. I hypothesize that many characters are likely to be influenced by selection but, using traditional approaches, will fail to observe selection on the measured characters, whereas non-parametric approaches may be more useful as a tool to detect selection differences among characters.

Philosophical Transactions of the Royal Society. Biological Sciences, 2012

Background/Question/Methods The distribution of orchids in the epiphytic or lithophytic environme... more Background/Question/Methods The distribution of orchids in the epiphytic or lithophytic environment is likely to result from a combination of factors including the interactions with other plant species. Here we tested for negative associations between bryophyte cover and early demography stages and positive associations of bryophyte cover on adult plants of , a riparian epiphytic and lithophytic tropical orchid. We also tested whether or not there was an association between the density of plants and the diversity and composition of bryophytes in our study area and whether or not the height of densest orchid aggregate within a phorophyte relative to the water line was related to the height 'moss' line across a rock substrate (indicative of flash flood disturbances). Results/Conclusions Bryophyte cover was not significantly different between phorophytes with neither high nor low orchid density when all plant stages were pooled nor when only the density of adult plants was cons...

PLOS ONE, 2015

The current live vaccinia virus vaccine used in the prevention of smallpox is contraindicated for... more The current live vaccinia virus vaccine used in the prevention of smallpox is contraindicated for millions of immune-compromised individuals. Although vaccination with the current smallpox vaccine produces protective immunity, it might result in mild to serious health complications for some vaccinees. Thus, there is a critical need for the production of a safe virus-free vaccine against smallpox that is available to everyone. For that reason, we investigated the impact of imiquimod and resiquimod (Toll-like receptors agonists), and the codon-usage optimization of the vaccinia virus A27L gene in the enhancement of the immune response, with intent of producing a safe, virus-free DNA vaccine coding for the A27 vaccinia virus protein. We analyzed the cellular-immune response by measuring the IFN-γ production of splenocytes by ELISPOT, the humoral-immune responses measuring total IgG and IgG2a/IgG1 ratios by ELISA, and the TH1 and TH2 cytokine profiles by ELISA, in mice immunized with our vaccine formulation. The proposed vaccine formulation enhanced the A27L vaccine-mediated production of IFN-γ on mouse spleens, and increased the humoral immunity with a TH1-biased response. Also, our vaccine induced a TH1 cytokine milieu, which is important against viral infections. These results support the efforts to find a new mechanism to enhance an immune response against smallpox, through the implementation of a safe, virus-free DNA vaccination platform.

Endangered Species Research, 2012

Lepanthes caritensis is a small epiphytic orchid endemic to Puerto Rico. Although this species is... more Lepanthes caritensis is a small epiphytic orchid endemic to Puerto Rico. Although this species is very rare and demographic studies show that its numbers are declining, it is not protected under the United States Federal Endangered Species Act (ESA). Furthermore, questions remain regarding its distribution, population size and ecological interactions, including host-specificity, which could influence its likelihood of extinction. The primary objective of this study was to document the overall population size and distribution of this orchid to determine whether it warrants federal listing. To this end, extensive surveys were conducted to document the current distribution and population size of L. caritensis. These data were used to classify the species’ rarity status according to criteria outlined by Rabinowitz, NatureServe and the IUCN. Results of these surveys indicate that the overall population of L. caritensis is larger and more widely distributed than previously thought. In addition, the species is not host-specific outside its originally described range, and is found on at least 4 different host species. Nevertheless, this species is indeed rare: it meets the criteria for the NatureServe category ‘critically imperiled’ and the IUCN category ‘Critically Endangered’. Consequently, the most important conclusion of this study is that this species warrants legal protection under the ESA, particularly if its population continues to decline.

Biodiversity and Conservation, 2010

The challenge of conservation biology is to make models that predict population dynamics and have... more The challenge of conservation biology is to make models that predict population dynamics and have a high probability of accurately tracking population change (increase, decrease, constancy). In this study we tested whether the transition model is accurate enough to predict population persistence and size 13 years down and whether after 13 years populations had achieved a stable stage distribution. We modeled 6 small populations of an epiphytic orchid using a Lefkovitch type analysis to predict population growth pattern based on monthly surveys for approximately 1.5 years. In addition, sensitivity and elasticity analyses were used to identify life stages with high sensitivity or elasticity that have the largest influence on population growth rate. We re-censused the populations 13 years after the first study and compared the structure of the populations to predictions based on the earlier census data. Effective population growth rates were similar to those expected except for one where the population went extinct. The prediction slightly (but not significantly) overestimated the actual population growth rates of some populations. Elasticity analysis revealed that the adult stage is critical in the life cycle. The observed stage distributions of the populations were not stable at the beginning of the survey and neither were they after 13 years. We suggest that this might be caused by external perturbations that result in unequal mortality between life stages and stochastic recruitment events. The ability of the matrices to predict population size approximately eight generations in the future is encouraging and warrants the continued use of these approaches for PVA.

Background and Aims Evaluation of population projection matrices (PPMs) that are focused on asymp... more Background and Aims Evaluation of population projection matrices (PPMs) that are focused on asymptotically based properties of populations is a commonly used approach to evaluate projected dynamics of managed populations. Recently, a set of tools for evaluating the properties of transient dynamics has been expanded to evaluate PPMs and to consider the dynamics of populations prior to attaining the stable-stage distribution, a state that may never be achieved in disturbed or otherwise ephemeral habitats or persistently small populations. This study re-evaluates data for a tropical orchid and examines the value of including such analyses in an integrative approach.

The science of conservation biology is the application of knowledge acquired about the biology of... more The science of conservation biology is the application of knowledge acquired about the biology of organisms to facilitate the persistence of species or control of invasive species. Habitat destruction results in population size reduction and sometimes in extinction; however, quantifying its impact is not a trivial undertaking. In many cases a minimal amount of science is needed to understand the concept that habitat destruction usually results in reduction of population size. However, if we are interested in more complex questions, such as when is habitat destruction excessive or what are the effects of habitat fragmentation and destruction, then scientific tools are required. One of the most challenging skills to be acquired is the intellectual framework to understand the interactions among individuals in a population and population-level interactions with the community. Taking a holistic approach to the scientific study of orchids in situ is more likely to result in positive conservation outcomes. In this paper we review some of the basic biological processes that affect species survival.

Orchid Science Letters, 2011

BioNews, The newsletter of the Dutch Caribbean Nature Alliance, 2013

Australasian Orchid Native Society-Victoria Chapter, 2005

Orchid Conservation, 2000

Proceedings of the 19th World Orchid Congress, Miami, 2009

Early in the history of evolutionary biology, orchids had a prominent role in providing evidence ... more Early in the history of evolutionary biology, orchids had a prominent role in providing evidence for natural selection. The unusual pollination mechanisms attracted the attention of Darwin (1877) who had argued that orchids offer strong evidence for natural selection and for the advantages of cross pollination. Since then, much effort has been devoted to describing pollination mechanisms van der Cingel, 1995). These reports contribute to Darwin's arguments, although it is not often stated explicitly. Most agree that there is a link between orchid pollination systems and orchid diversity but the distinction between cause and effect is often not clear.

Caribbean Naturalist, 2013

The distribution of orchids in the epiphytic or lithophytic environment is likely to result from ... more The distribution of orchids in the epiphytic or lithophytic environment is likely to result from the interactions with other plant species. We tested for associations between bryophyte cover and diversity and the densities of different demographic stages (seedlings and juveniles vs adults) of Lepanthes rupestris (Rock Babyboot Orchid), a riparian tropical orchid. Given that this species is predominantly lithophytic and grows near streams, we considered whether or not the location of the densest orchid aggregate within a rock substrate was also related to the location of the "bryophyte line" across the rocky substrate (a potential indicator of maximum water levels for a stream). We found that substrates with thick bryophyte covers had lower densities of early demographic plant stages relative to ones with thin covers. In contrast, higher adult densities were recorded on substrates with thick bryophyte covers relative to substrates with thin bryophyte covers. Orchid density was positively associated with bryophyte species richness, but this association is driven mostly by diversity of mosses and not by diversity of liverworts. The location of the densest L. rupestris patch within a substrate was positively related to the recorded location for the bryophyte line forming across a rock substrate. Overall results suggest that the potential interactions between bryophytes and L. rupestris are likely to be dynamic throughout the life cycle of these orchids. We discuss the potential mechanisms of these interactions (negative ones acting during early stages and positive ones acting at later stages) and the role that natural disturbance regimes along streams (i.e., flash floods) may play in the population dynamics of this species.

Endangered Species Research, 2012

Lepanthes caritensis is a small epiphytic orchid endemic to Puerto Rico. Although this species is... more Lepanthes caritensis is a small epiphytic orchid endemic to Puerto Rico. Although this species is very rare and demographic studies show that its numbers are declining, it is not protected under the United States Federal Endangered Species Act (ESA). Furthermore, questions remain regarding its distribution, population size and ecological interactions, including hostspecificity, which could influence its likelihood of extinction. The primary objective of this study was to document the overall population size and distribution of this orchid to determine whether it warrants federal listing. To this end, extensive surveys were conducted to document the current distribution and population size of L. caritensis. These data were used to classify the species' rarity status according to criteria outlined by Rabinowitz, NatureServe and the IUCN. Results of these surveys indicate that the overall population of L. caritensis is larger and more widely distributed than previously thought. In addition, the species is not host-specific outside its originally described range, and is found on at least 4 different host species. Nevertheless, this species is indeed rare: it meets the criteria for the NatureServe category 'critically imperiled' and the IUCN category 'Critically Endangered'. Consequently, the most important conclusion of this study is that this species warrants legal protection under the ESA, particularly if its population continues to decline.

Applied and Environmental Microbiology, 2012

Novel markers of fecal pollution in tropical waters are needed since conventional methods recomme... more Novel markers of fecal pollution in tropical waters are needed since conventional methods recommended for other geographical regions may not apply. To address this, the prevalence of thermotolerant coliforms, enterococci, coliphages, and enterophages was determined by culture methods across a watershed. Additionally, human-, chicken-, and cattle-specific PCR assays were used to identify potential fecal pollution sources in this watershed. An enterococcus quantitative PCR (qPCR) assay was tested and correlated with culture methods at three sites since water quality guidelines could incorporate this technique as a rapid detection method. Various rainfall events reported before sample collection at three sites were considered in the data analyses. Thermotolerant coliforms, enterococci, coliphages, and enterophages were detected across the watershed. Human-specific Bacteroides bacteria, unlike the cattle-and chicken-specific bacteria, were detected mostly at sites with the corresponding fecal impact. Enterococci were detected by qPCR as well, but positive correlations with the culture method were noted at two sites, suggesting that either technique could be used. However, no positive correlations were noted for an inland lake tested, suggesting that qPCR may not be suitable for all water bodies. Concentrations of thermotolerant coliforms and bacteriophages were consistently lower after rainfall events, pointing to a possible dilution effect. Rainfall positively correlated with enterococci detected by culturing and qPCR, but this was not the case for the inland lake. The toolbox of methods and correlations presented here could be potentially applied to assess the microbial quality of various water types.

Lankesteriana, 2011

Natural selection and genetic drift are the two processes that can lead to cladogenesis. Without ... more Natural selection and genetic drift are the two processes that can lead to cladogenesis. Without a doubt the great diversity and floral adaptation to specific pollinators are likely consequences of natural selection. Detecting natural selection in the wild requires measuring fitness advantage for specific characters. However, few published orchid studies demonstrate that floral characters are influenced by natural selection. If selection is temporal or weak, then this may explain why we rarely find selection on floral characters. Alternatively, selection on a character may not follow commonly used mathematical models that are based on linear, disruptive, and stabilizing selection and serve as null models. Moreover, fitness advantages are usually tested on general models, which assume that the parameters are normally distributed. If we forego the idea that selection follows specific mathematical models and Gaussian distribution and that all types of selection landscapes and other types of distributions (binomial, Poisson) are possible, we may discover evidence that the process of selection does play a role in explaining the great diversity of orchids. Here I show and compare the use of traditional and non-parametric approaches for measuring selection of floral characters. I hypothesize that many characters are likely to be influenced by selection but, using traditional approaches, will fail to observe selection on the measured characters, whereas non-parametric approaches may be more useful as a tool to detect selection differences among characters.

Philosophical Transactions of the Royal Society. Biological Sciences, 2012