This study evaluated the methane (CH4) production capacity of microbial consortia from three neotropical lakes at different altitudes: Mojanda (4,263 m.a.s.l., 10°C), Papallacta (3,250 m.a.s.l., 14°C), and Caimanes (510 m.a.s.l., 25°C). Specific methanogenic activity (SMA) and biochemical methane potential (BMP) from cellulose were assessed at two temperatures (the original lake temperature and 37°C) and three different inoculum-to-substrate ratios (ISR of 1, 2, and 4). The highest SMA values were observed at 37°C, being 0.021, 0.011, and 0.009 g COD/gVS·d for Caimanes, Papallacta, and Mojanda, respectively. At their original temperatures, only Mojanda and Caimanes showed activity (0.007 and 0.014 COD/gVS·d), which was significantly lower. Methane yields from cellulose were also highly temperature-dependent. The highest yield was achieved by the Caimanes consortium at 37°C (409 NmL CH4/gVS), while at its native 25°C, the yield was 147 NmL CH4/g VS. The Mojanda consortium, from the highest altitude, produced methane even at 10°C (26 NmL CH4/gVS), while at 37°C was 137 NmL CH4/gVS. No activity was detected for Papallacta at its original temperature (14°C) but 203 NmL CH4/gVS for 37°C. These results demonstrate the strong temperature dependence of these consortia and classify them as psychrotrophic rather than psychrophilic. This sensitivity suggests a potential for increased greenhouse gas emissions from these lakes under climate warming scenarios. Furthermore, the resilience and cellulolytic activity at low temperatures exhibited by these consortia highlight their potential for specialized applications in anaerobic digestion, such as bioaugmentation for the treatment of complex wastes.
The Sierra Norte of Oaxaca, M & eacute;xico, because of its high biodiversity, is a good candidate for studying the possible effects of climate change on its flora distribution. Currently, several modelling tools have been developed to facilitate the prediction of present and future species distribution. The objective of this study is to evaluate the impact of climate change on the distribution of four locally important medicinal plant species from the Asteraceae family (Heterotheca inuloides, Laennecia filaginoides, Pinaropappus roseus, and Tagetes lucida). The analysis was done using the maximum entropy algorithm under three different time periods: the present, 2050, and 2070, projected to the Representative Concentration Pathways (RCP 4.5 and RCP 8.5) future climate scenarios. Using a principal component analysis, we selected the variables that best explained each of the models. The modelling results showed that it is difficult to identify a consistent pattern of species distribution under the different scenarios and time periods since the species responses differed among time periods and scenarios. Laennecia filaginoides is the only species whose distribution increases by 2050 and 2070 under both scenarios analyzed. Our results may support future conservation strategies in the communities where species are distributed and utilized due to their demonstrated capacity to alleviate different illnesses.
The concept of a "community" as a form of organization for natural biological systems is both widespread and widely accepted within the ecological and biological sciences. Communities have been defined as groups of organisms that interact in ways that denote interdependence between individuals and taxa (e.g. as defined by "food webs") but they have also been defined as groups of co-occurring organisms that are assumed to interact by virtue of their shared spatiotemporal existence. The latter definition has been debated and challenged in the literature, with mounting evidence for co-occurrence being more indicative of coincident ecological niches in space and time rather than being evidence of ecological interaction or dependency. Using a dataset of 460 Costa Rican bird species divided into breeding and non-breeding season datasets, we empirically demonstrate the ways in which co-occurrence can create illusory communities based on similar occupied ecological niches and similar patterns of co-occurrence at different times of year. We discuss the importance of discerning coincidental co-occurrence from true ecological interactions that would manifest a true community, and further address the importance of differentiating communities of co-occurrence from communities of demonstrable ecological interaction. While co-occurrence is a necessary aspect of interspecific interactions, we discuss and demonstrate here that such co-occurrence does not make a community, nor should explicit patterns of co-occurrence be seen as evidence for evolutionarily important ecological interactions.
ABSTRACTAnimals endemic to tropical mountains are known to be especially vulnerable to climate change. The Cordillera de Talamanca (Costa Rica and Panama) is a geographically isolated mountain chain and global biodiversity hotspot, home to more than 50 endemic bird species. We used eBird community science observations to predict the distributions of a suite of 48 of these endemic birds in 2006-2015, and in 2070, under four climate change scenarios. Species distributions were predicted using program Maxent, incorporating elevation, satellite derived habitat data, and WorldClim climate variables. Model fit, as assessed by Area under the Receiver Operator Curve (AUC) was very high for most species, ranging from 0.877 to 0.992 (mean of 0.94). We found that most species are predicted to undergo range contractions by 2070, with a mean of 15% under modest climate change (RCP 2.6) up to a mean of 40% under more severe climate change (RCP 8.5). Most of the current ranges of these species are within existing protected areas (average of 59% in 2006-2015), and with prospective range contractions, the importance of these protected areas is forecast to increase. We suggest that these predicted range declines should elevate conservation concerns for this suite of species, and vigilance, in the form of better population monitoring, is urgently needed.
Plant survival in semi-arid climates depends on morphological, anatomical, and physiological adjustments that determine survival under limiting environmental conditions. In this study, anatomical and morphological characteristics of three herbaceous species with different growth habits were determined: a tall herb, Mesosphaerum suaveolens (tall), Stachytarpheta sanguinea (short), and Jacquemontia evolvuloides (climbing). Fully expanded leaves were collected from three sites in each of three different natural regeneration periods in a seasonally dry tropical forest. Leaf, specific leaf area, epidermis, cuticle, parenchyma, and mesophyll thicknesses; stomatal and trichome densities were measured. All three species have stomata and trichomes on both leaf surfaces and higher densities on the abaxial surface than the adaxial surface. M. suaveolens and S. sanguinea have unusual leaf morphological and anatomical adjustments, with a larger leaf area in the more open and youngest site, but thicker abaxial and adaxial epidermis and mesophyll in the oldest site which has the closest canopy stratum. J. evolvuloides has more usual adjustments, with a smaller specific leaf area and thinner epidermis and isobilateral parenchyma in the youngest site, being better acclimatized to low water availability and high light incidence. Therefore, M. suaveolens and S. sanguinea have unique acclimatization strategies for different environmental conditions.
