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I investigated the size, composition and persistence of the seed-bank in primary forests, secondary forests and old-fields in southern Mexico. I also assessed the contribution of the seed-bank to regeneration relative to other propagule sources. In all habitats, I removed by hand all plants and litter and excluded the seed-rain. For one year, I counted the number of plant species (5–50 cm tall) emerged and grouped them into different growth-forms: trees, shrubs, palms, herbs, woody lianas, epiphytes and hemi-epiphytes. A total of 95 species emerged. The seed-bank size, composition and persistence showed strong variation among successional stages. Emergence was low for primary and secondary forests, but high for old-fields (19, 26, and 68 plants per m−2, respectively). Herbs were the most abundant in the seed-bank and palms the less. Time had a negative effect on seed-bank size in primary forests and old-fields; whereas for secondary forests size remained constant throughout the year. The number of emerged plants in different growth-forms changed significantly across time for all successional stages. Overall, the seed-bank provided a greater number of plants in old-fields relative to other propagule sources combined. The results showed that forest modification alters the input of propagules throughout the seed-bank for different plant growth-forms.

We evaluated the structure of intrapopulation howler monkey-plant interactions by focusing on the plant species consumed by different sex and age classes in continuous and fragmented forests in southern Mexico. For this we used network analysis to evaluate the impact of fragmentation on howler population traits and on resource availability and food choice. A total of 37 tree and liana species and seven plant items (bark, immature fruits, flowers, mature fruits, immature leaves, mature leaves and petioles) were consumed, but their relative consumption varied according to sex and age classes and habitat type. Overall, adult females consumed the greatest number of plant species and items while infants and juveniles the lowest. For both continuous and fragmented forests, we found a nested diet for howler monkey-plant networks: diets of more selective monkeys represent subsets of the diets of other individuals. Nestedness was likely due to the high selectivity of early life stages in specific food plants and items, which contrasts with the generalized foraging behaviour of adults. Information on the extent to which different plant species and primate populations depend on such interactions in different habitats will help to make accurate predictions about the potential impact of disturbances on plant-animal interaction networks.

We report 4 new records of Heliconia species (Heliconiaceae) for the region of Chajul, one of the most studied sites of the Mexican Lacandona. Records are for H. champneiana Griggs cv. Maya Gold, H. latispatha Bentham cv. Orange Gyro, H. vaginalis Bentham, and H. wagneriana Petersen. We provide a brief description of morphological and ecological traits of the species and demonstrate the high potential they have to be cultivated in biodiversity-friendly cropping systems. We suggest the use of Heliconia in the enrichment of secondary forests and forest fragments as an alternative of combining forest management with biological conservation.Se registran por primera vez 4 especies de Heliconia (Heliconiaceae) para la región de Chajul, uno de los sitios más estudiados de la lacandona mexicana. Los nuevos registros son para H. champneiana Griggs cv. Maya Gold, H. latispatha Bentham cv. Orange Gyro, H. vaginalis Bentham, y H. wagneriana Petersen. Se presenta una breve descripción acerca de las características morfológicas y ecológicas de las especies y se demuestra el alto potencial que tienen para ser cultivadas en plantaciones amigables de la biodiversidad. Se sugiere el uso de Heliconia en el enriquecimiento de bosques secundarios y fragmentos de selva como una alternativa de combinar manejo forestal con conservación biológica.

Abstract Background Land-use change frequently affects faunistic populations and communities. To achieve successful conservation strategies, we need suitable information about species distribution and the causes of extinction risk. Many amphibian species depend on riparian vegetation to complete their life cycles. About 41% of amphibian species are globally threatened, and accurate estimations of population size, species richness and the identification of critical habitats are urgently needed worldwide. To evaluate the magnitude of changes in species richness and demography, estimations that include detection probability are necessary. In this study, we employed multi-species occupancy models to estimate detection probability and the effect of land cover type (i.e., cropland, artificial pasture, secondary and mature forest) in a 500-m radius on the occupancy probability and richness of diurnal amphibians in 60 riparian zones in the state of Michoacán in central Mexico. Furthermore, we evaluated the potential of the endemic salamander Ambystoma ordinarium as a flagship species for the conservation of other native amphibian species. Results We registered a total of 20 amphibian species in the diurnal assemblage, of which 10 species are considered at risk of extinction. We found that cropland was the most important land-use type for explaining amphibian distribution in riparian zones, with negative effects on most amphibian species. We found no differences in species richness between zones with and without A. ordinarium. In riparian zones occupied by A. ordinarium, however, we found a higher number of species at risk of extinction. Conclusions Our findings showed negative effects of croplands on the distribution of most amphibian species. The riparian zones are important for the maintenance of native diurnal amphibian communities and A. ordinarium can act as a flagship species for the conservation of threatened amphibian species.

Black-eared Rice Rat, Handleyomys melanotis (Thomas, 1893), is a small, abundant rodent thought endemic to Mexico. We present a new record of this rat on Cocinas Island off the Chamela coast of Jalisco, Mexico. On this protected island located at 19.5°N, 105.1°W, we captured 11 specimens with the physical characteristics that confirm their identity as H. melanotis. We explore the possible implications of this species on Cocinas Island.

Anthropogenic disturbance of tropical humid forests leads to habitat loss, biodiversity decline, landscape fragmentation, altered nutrient cycling and carbon sequestration, soil erosion, pest/pathogen outbreaks, among others. Nevertheless, the impact of these alterations in multitrophic interactions, including host–pathogen and vector–pathogen dynamics, is still not well understood in wild plants. This study aimed to provide insights into the main drivers for the incidence of herbivory and plant pathogen damage, specifically, into how vegetation traits at the local and landscape scale modulate such interactions. For this purpose, in the tropical forest of Calakmul (Campeche, Mexico), we characterised the foliar damage caused by herbivores and pathogens in woody vegetation of 13 sampling sites representing a gradient of forest disturbance and fragmentation in an anthropogenic landscape from well preserved to highly disturbed and fragmented areas. We also evaluated how the incidence of such damage was modulated by the vegetation and landscape attributes. We found that the incidence of damage caused by larger, mobile, generalist herbivores, was more sensitive to changes in landscape configuration, while the incidence of damage caused by small and specialised herbivores with low dispersal capacity was more influenced by vegetation and landscape composition. In relation to pathogen symptoms, the herbivore-induced foliar damage seems to be the main factor related to their incidence, indicating the enormous importance of herbivorous insects in the modulation of disease dynamics across tropical vegetation, as they could be acting as vectors and/or facilitating the entry of pathogens by breaking the foliar tissue and the plant defensive barriers. The incidence of pathogen damage also responded to vegetation structure and landscape configuration; the incidence of anthracnose, black spot, and chlorosis, for example, were favoured in sites surrounded by smaller patches and a higher edge density, as well as those with a greater aggregation of semi-evergreen forest patches. Fungal pathogens were shown to be an important cause of foliar damage for many woody species. Our results indicate that an increasing transformation and fragmentation of the tropical forest of southern Mexico could reduce the degree of specialisation in plant–herbivore interactions and enhance the proliferation of generalist herbivores (chewers and scrapers) and of mobile leaf suckers, and consequently, the proliferation of some symptoms associated with fungal pathogens such as fungus black spots and anthracnose. The symptoms associated with viral and bacterial diseases and to nutrient deficiency, such as chlorosis, could also increase in the vegetation in fragmented landscapes with important consequences in the health and productivity of wild and cultivated plant species. This is a pioneering study evaluating the effect of disturbances on multitrophic interactions, offering key insights on the main drivers of the changes in herbivory interactions and incidence of plant pathogens in tropical forests.

Tropical rain forest fragmentation is considered one of the principal drivers of biodiversity loss worldwide. Fragmentation and defaunation of tropical rain forests affect the maintenance of their biodiversity in a myriad of ways. Old-growth forest plant and animal species are more likely to suffer from local extinction, not only because fragments frequently represent low quality habitats but also because of the loss of biotic interactions such as seed dispersal. In this study, we evaluated the maintenance of tree species diversity in the face of habitat fragmentation in southern Mexico using different approaches. Firstly, we used community phylogeny at different tree life stages (i.e., seeds, seedlings and adults). Secondly, we categorised plant species in different life stages into functional groups according to seed size (small seeds < 1 cm length and large seeds > 1 cm length) and, finally, by dispersal syndrome (predominantly primate dispersed). We searched for three sites of continuous forest as experimental controls where two important seed dispersers coexist, the howler (Alouatta pigra) and spider (Ateles geoffroyi) monkeys, and six forest fragments of similar sizes (ca. 3–6 ha). Three fragments were occupied only by howler monkeys, and three had no primates. We compared entire assemblages as well as assemblages of small-seeded and large-seeded species separately to determine the phylogenetic structure and patterns of species richness and the density of adult trees (> 10 cm dbh), seedlings (10–100 cm tall) and seed assemblages. Fragments and continuous forest differed in taxonomic species richness and density at all life stages when large-seeded species mainly dispersed by primates were solely considered, with numbers in unoccupied fragments being consistently lower than in continuous forests and occupied fragments. Phylogenetic clustering occurred in all habitats and for all life stages, predominantly for the seedling stage, indicating that the understory community is assembled via environmental filtering (including both biotic and abiotic processes). Habitats occupied by primates tended to present a higher phylogenetic clustering than unoccupied fragments, suggesting that primates select phylogenetically-related species in their diets and, importantly, that these foraging behaviours influence seedling recruitment patterns. The loss of taxonomic and functional biodiversity and the non-random extinction of tree species principally dispersed by primates, represents part of the evolutionary history that is being lost throughout fragmentation.

Some animal species exhibit sex-specific patterns as an adaptation to their habitats, however, adaptability to a human-dominated landscape is commonly explored without considering intraspecific sexual differences. Differences between males and females lead to a sexual segregation in habitat use. In southern Mexico, we explored sex-specific responses to landscape modification of six common species of phyllostomid bats: Artibeus jamaicensis, A. lituratus, Sturnira lilium, Carollia perspicillata, Glossophaga soricina, and Platyrrhinus helleri using riparian corridors within continuous forest and cattle pastures. Furthermore, we explored sex related responses to vegetation attributes (i.e., tree height and basal area) and seasonality (i.e., wet and dry seasons). Overall, capture rates were significantly skewed toward females and riparian corridors in pastures. Females of G. soricina exhibited a strong positive relationship with greater tree height and basal area. Seasonality was important for A. lituratus and S. lilium females, only. The results indicate a sexual driven response of bats to habitat modification. The high energetic demands of females associated to reproduction could lead to foraging into riparian corridors in pastures. The presence of large trees along riparian corridors in pastures may help maintaining a diverse and dynamic bat community in modified tropical landscapes.

Habitat loss affects the nature of biotic interactions in all ecosystems and at all levels of the food web. Nevertheless, little attention has been given to soil nematodes in tropical habitats despite their important role in ecosystem functioning worldwide. Here, we analyzed the influence of anthropogenic habitat disturbance on the absolute and relative density and composition (i.e., trophic guilds) of soil nematode communities associated with the rhizosphere of the tropical herb Heliconia collinsiana in continuous mature forests and human-induced secondary forests. We compared nematode densities based on the following feeding guilds: bacterivores, fungivores, herbivores and predators. Thereafter, we classified herbivorous nematodes into genera and described soil properties in both habitat types including pH, electrical conductivity, and organic matter content. Herbivores were significantly the most abundant feeding guild for both habitats represented by Criconemella spp., Helicotylenchus spp., and Meloidogyne spp., which showed no significant differences in density between habitats. Relative but not absolute nematode density differed between habitats, with fungivore nematodes being significantly lower in secondary forests. No significant differences in soil properties were detected. Overall, our results suggest that forest disturbance affects the nematode community associated with the rhizosphere of H. collinsiana which may affect forest succession and the dynamics of the soil biota. Our study contributes to the understanding of biotic interactions in conserved and disturbed tropical habitats.

Interactions between cultivated and wild plants with their fungal pathogens have strong ecological, evolutionary and economic implications. Antagonistic interactions, however, have been scantily studied in an applied context by using ecological networks, phylogeny and spatial ecology concurrently. In this study, we describe for the first time, the topological structure of plant-fungi networks involving species of the genus Fusarium and their native and introduced (exotic) cultivated host plants in Mexico. For this, we based our study on a recent database describing the attack on 75 native and introduced plant species, including 35 species of the genus Fusarium. Host plant species varied in their degree of phylogenetical relatedness (Monocots and Dicots) and spatial geographical distribution. Therefore, we also tested whether or not plant-Fusarium networks are phylogenetically structured and highlighted the spatial correlation between pathogens and their host plants across the country. In general, the pathogen-plant network is more specialized and compartmentalized in closely related taxa. Closely related hosts are more likely to share the same pathogenic Fusarium species. Host plants are present in different ecosystems and climates, with regions having more cultivated plant species presenting the highest number of fusaria pathogens. From an economic standpoint, different species of the same taxonomic family may be more susceptible to being attacked by the same species of Fusarium, whereas from an ecological standpoint the movement of pathogens may expose wild and cultivated plants to new diseases. Our study highlights the relevance of interaction intimacy in structuring trophic relationships between plants and fusaria species in native and introduced species. Furthermore, we show that the analytical tools regarding host distribution and phylogeny could permit a rapid assessment of which plant species in a region are most likely to be attacked by a given fusaria.

The maintenance of seedling diversity of animal-dispersed tree species is fundamental for the structure and function of forest patches in fragmented tropical rainforests. Nonetheless, the effects of landscape structure at different spatial scales on α- and β-diversity of tree seedling communities are recently explored. Using a multi-scale approach, we assessed the relative effect of landscape composition and configuration on α- and β-diversity of animal-dispersed seedlings within 16 forest patches in the Lacandona rainforest, Mexico. We assessed these effects at 13 spatial scales (from 300 to 1500 m radius, at 100 m intervals) for three metrics of effective number of species considering α- and β-diversity. We found that α-diversity was largely affected by landscape composition and β-diversity by landscape configuration. On the one hand, the amount of secondary forest influenced α-diversity. Additionally, species richness increased in landscapes with highly aggregated forest patches. On the other hand, β-diversity was affected positively by forest fragmentation and negatively by the edge contrast of forest patches with the surrounding matrix. Our findings indicate that landscape configuration is a strong driver of seedling diversity in highly deforested rainforests. Promoting forest patches and secondary forests through payment for ecosystem services' programs, favoring matrix quality within land-sharing schemes of smallholder agriculture and secondary forest management, and identifying restoration opportunities for assisted or unassisted natural regeneration are urgently needed for conservation of seedling diversity in human-modified tropical landscapes.

The effect of anthropogenic disturbance on plant community traits and tradeoffs remains poorly explored in tropical forests. In this study, we aimed to identify tradeoffs between defense and other plant functions related to growth processes in order to detect potential aboveground and edaphic environmental conditions modulating traits variation on plant communities, and to find potential assembly rules underlying species coexistence in secondary (SEF) and old-growth forests (OGF). We measured the foliar content of defense phytochemicals and leaf traits related to fundamental functions on 77 species found in SEF and OGF sites in the Jalisco dry forest ecoregion, Mexico, and we explored (1) the trait-trait and trait-habitat associations, (2) the intra and interspecies trait variation, and (3) the traits-environment associations. We found that phytochemical content was associated with high leaf density and leaf fresh mass, resulting in leaves resistant to drought and high radiation, with chemical and physical defenses against herbivore/pathogen attack. The phytochemicals and chlorophyll concentrations were negatively related, matching the predictions of the Protein Competition Model. The phylogenetic signal in functional traits, suggests that abundant clades share the ability to resist the harsh biotic and abiotic conditions and face similar tradeoffs between productive and defensive functions. Environmental filters could modulate the enhanced expression of defensive phytochemicals in SEF, while, in OGFs, we found a stronger filtering effect driving community assembly. This could allow for the coexistence of different defensive strategies in OGFs, where a greater species richness could dilute the prevalence of pathogens/herbivores. Consequently, anthropogenic disturbance could alter TDF ecosystem properties/services and functioning.

Habitat loss and fragmentation are recognized as affecting the nature of biotic interactions, although we still know little about such changes for reptilian herbivores and their hindgut nematodes, in which endosymbiont interactions could range from mutualistic to commensal and parasitic. We investigated the potential cost and benefit of endosymbiont interactions between the spur-thighed tortoise (Testudo graeca L.) and adult oxyurid nematodes (Pharyngodonidae order Oxyurida) in scrublands of southern Spain. For this, we assessed the association between richness and abundance of oxyurid species with tortoises’ growth rates and body traits (weight and carapace length) across levels of habitat loss (low, intermediate and high). Furthermore, by using an intrapopulation ecological network approach, we evaluated the structure and diversity of tortoise–oxyurid interactions by focusing on oxyurid species infesting individual tortoises with different body traits and growth rates across habitats. Overall, tortoise body traits were not related to oxyurid infestation across habitats. Oxyurid richness and abundance however, showed contrasting relationships with growth rates across levels of habitat loss. At low habitat loss, oxyurid infestation was positively associated with growth rates (suggesting a mutualistic oxyurid–tortoise relationship), but the association became negative at high habitat loss (suggesting a parasitic relationship). Furthermore, no relationship was observed when habitat loss was intermediate (suggesting a commensal relationship). The network analysis showed that the oxyurid community was not randomly assembled but significantly nested, revealing a structured pattern for all levels of habitat loss. The diversity of interactions was lowest at low habitat loss. The intermediate level, however, showed the greatest specialization, which indicates that individuals were infested by fewer oxyurids in this landscape, whereas at high habitat loss individuals were the most generalized hosts. Related to the latter, connectance was greatest at high habitat loss, reflecting a more uniform spread of interactions among oxyurid species. At an individual level, heavier and larger tortoises tended to show a greater number of oxyurid species interactions. We conclude that there is an association between habitat loss and the tortoise–oxyurid interaction. Although we cannot infer causality in their association, we hypothesize that such oxyurids could have negative, neutral and positive consequences for tortoise growth rates. Ecological network analysis can help in the understanding of the nature of such changes in tortoise–oxyurid interactions by showing how generalized or specialized such interactions are under different environmental conditions and how vulnerable endosymbiont interactions might be to further habitat loss.

We analyzed the influence of natural and anthropogenic habitat disturbance on the structure of invertebrate communities living on two species of Heliconia herbs. We compared the invertebrate community structure associated to both species growing in natural forest gaps, on road edges for H. latispatha, and in riparian vegetation for H. collinsiana. We assessed the topological structure of individual-based Heliconia–invertebrate networks. Species richness was greater in H. collinsiana inhabiting riparian vegetation but no differences were found in the diversity of invertebrates for any Heliconia species and habitat. Invertebrate abundance was greater in gaps for H. latispatha and in riparian vegetation for H. collinsiana showing a species turnover in human disturbed habitats. The invertebrate community was not randomly assembled but highly nested, revealing a structured pattern for all habitat conditions. Heliconia–invertebrate network properties appear to be maintained in human disturbed habitats, despite differences in species richness, abundance and composition and host number and quality. Our study contributes to the understanding of the structure of ecological interactions in contrasting habitats. Because they provide food and habitat for the associated fauna and several microhabitats for colonization, heliconias could be used as habitat elements for invertebrate conservation in human impacted landscapes. Keywords: Habitat elements, Heliconia collinsiana, Heliconia latispatha, Individual-based networks, Plant–invertebrate interactions

The "aje" (Llaveia axin axin) is a parasitic hemipteran of various tree species in tropical dry forests of Mexico and Guatemala. Females produce fatty extracts used since prehispanic times (i.e., traditional medicine and as raw material to produce handcrafts). However, very little is known about its biology and conservation status. In Michoacán and Guerrero States (Mexico), fifteen localities with historical reports of "aje" were visited 4 times (2006-2007). The incidence, seasonal abundance and distribution, host species, tree size and section preference, were determined. Only 3 populations in 2 localities were found at low altitudes (< 300 m asl), close to water sources, with only 1 host tree, Acacia cochliacantha. Females were mostly found at the base of the trunk, but showed no preference for any tree size. July (2007) was the month with greater abundance. The "aje" seems highly threatened with local extinction, due to their fragmented relict populations and rapid destruction of its habitat and host species, which is considered as a weed. More basic information on its biology and population dynamics is urgently needed to implement any conservation strategy. In addition, the management of the "aje" should take into consideration biological, pharmacological and cultural connotations.El "aje" (Llaveia axin axin) es un hemíptero parásito de especies de árboles del bosque tropical seco de México y Guatemala. Las hembras producen extractos grasos utilizados por el hombre desde tiempos prehispánicos (i.e., medicina tradicional y como materia prima para producir la técnica artesanal de maque). Sin embargo, se conoce muy poco sobre su biología y estado de conservación. En los estados de Michoacán y Guerrero, se visitaron, en cuatro ocasiones (2006-2007), 15 localidades con reportes históricos del "aje". Se determinó la incidencia, abundancia y distribución estacional del "aje", así como las especies hospederas y preferencia por sección y tamaño de árbol. Se localizaron tres poblaciones en dos localidades (< 300 m snm), cercanas a cuerpos de agua, y se encontró presente en un sólo hospedero, Acacia cochliacantha. El "aje" fue comúnmente encontrado en la base del tronco principal, sin mostrar preferencia por el tamaño de árbol. Julio (2007) fue el mes con mayor abundancia. El "ajé" está amenazado por la extinción local de sus poblaciones, debido a su distribución agregada y a la destrucción de su hábitat y por la eliminación de su especie hospedera, considerada como maleza. Urge obtener información básica sobre su biología y dinámica poblacional, así como la implementación de alguna estrategia de conservación. El manejo del "aje" debe considerar connotaciones biológicas, farmacológicas y culturales.

The Los Tuxtlas Reserve has been heavily deforested and fragmented since the 1970’s. Although the flora of Los Tuxtlas has been described previously, most floristic lists come from the large forest reserve of the Los Tuxtlas field station. Here we present a check list of Angiosperms recorded in 45 rainforest fragments (< 1 to 266 ha) located in three landscapes with different levels of deforestation. We sampled all trees, shrubs, lianas, palms and herbs with diameter at breast height (dbh) Ā 2.5 cm within ten 50 m x 2 m plots per fragment. We recorded 9,435 plants belonging to 73 families and 372 species. Fabaceae, Rubiaceae, and Moraceae were best represented. Eight species are classified as Endangered by the Mexican government, and five are human-introduced species. We conclude that the conservation and restoration of all the remaining rainforest fragments are necessary to effectively preserve the plant diversity of this region.

Tropical rain forest fragmentation affects biotic interactions in distinct ways. Little is known, however, about how fragmentation affects animal trophic guilds and their patterns of interactions with host plants. In this study, we analyzed changes in biotic interactions in forest fragments by using a multitrophic approach. For this, we classified arthropods associated with Heliconia aurantiaca herbs into broad trophic guilds (omnivores, herbivores and predators) and assessed the topological structure of intrapopulation plant-arthropod networks in fragments and continuous forests. Habitat type influenced arthropod species abundance, diversity and composition with greater abundance in fragments but greater diversity in continuous forest. According to trophic guilds, coleopteran herbivores were more abundant in continuous forest and overall omnivores in fragments. Continuous forest showed a greater diversity of interactions than fragments. Only in fragments, however, did the arthropod community associated with H aurantiaca show a nested structure, suggesting novel and/or opportunistic host-arthropod associations. Plants, omnivores and predators contributed more to nestedness than herbivores. Therefore, Heliconia-arthropod network properties do not appear to be maintained in fragments mainly caused by the decrease of herbivores. Our study contributes to the understanding of the impact of fragmentation on the structure and dynamics of multitrophic arthropod communities associated with a particular plant species of the highly biodiverse tropical forests. Nevertheless, further replication of study sites is needed to strengthen the conclusion that forest fragmentation negatively affects arthropod assemblages.