THE USE OF INDICATOR GROUPS FOR MEASURING BIODIVERSITY AS RELATED TO COMMUNITY STRUCTURE AND FUNCTION

In ihis study we discuss the reasons for using indicator groups to measure biodivers'.ty at the species level ("organismal diversity" sensu Harper and Hawksworth). We further explore our previous proposals for the use of dung beetles belongmg ro the subfamily Scarabaeinae (Insecta: Coleóptera) as an indicator group for studying the types of communities found in tropical forests and derived formations, particularly those created by human activity. We present a method for obtaining quantifiable Information that allows comparative stuidies to be done, as well as an analysis of the effects ot human activilies that result in the alteration, fragmentation and destruction of natural communities. Although emphasis is placed on The mdicator group and the communities selected, we propose that this analysis of biodiversity can be used with other groups and in different community types, The arguments we present for the use of indicalor groups can he applied to different ways of studying biodivorsitv al the species level, however this study focases on presenting appropriate rnethodology for ecological analysis; that is, for the study of local biodiversity as an element for tire interpretation of community structure and functionEn este trabajo se discuten las razones para utilizar grupos indicadores en la medida do la biodiversidad a nivel de especies (diversidad organismal de Harper y Hawksworth). Se profundizan nuestras propuestas anteriores para el uso de los escarabajos del estiércol de la subfamilia Scarabaeinae (Insecta: Cnleoptera) como grupo indicador para estudiar los tipos de comunidades que conforman los bosques tropicales y formaciones derivadas, especialmente por la acción antrópica. Se plantea cómo obtener una información cuantificable que permita realizar estudios comparativos, así como un análisis de los efectos de la acción humana al alterar, fragmentar y destruir las comunidades naturales. Aunque el énfasis se pone en el grupo indicador y las comtimdades escogidas, se plantea este análisis de la biodivorsidad para ser utilizado con otros grupos y en diferentes tipos de comunidad. Aunque todo lo que planteamos como argumentos para el análisis a través de grupos indicadores puede aplicarse a distintos enfoques del estudio de la biodiversidad a nivel de especies, este trabajo se concentra en presentar la metodología adecuada para el análisis ecológico. Es decir, para el estudio de la biodtversidad puntual como elemento para la interpretación de la estructura y función de las comunidades

The relationships between dung beetles and monkeys in the Neotropical region

The relationship between dung beetles and arboreal mammals has been scarcely studied, and many of the reports refer to observations without a standardized methodology. The accelerated loss of tropical forests urges us to understand this mutualistic association. Using our studies on arboreal dung beetles in the Palenque Archaeological Zone-National Park, Mexico, as a baseline, we analyzed the information on arboreal dung beetles in Neotropical forests in Mexico and around the world. Canthon euryscelis Bates, 1867, Canthon angustatus Harold, 1867, Canthon subhyalinus Harold, 1867, and Canthon femoralis (Chevrolat, 1834) are the main species collected in trees of Palenque, Onthophagus maya Zunino, 1981 and other non-Scarabaeinae species were occasionally collected from trees in Palenque. The small Canthon species are skilled fliers strongly relationship with monkeys in Palenque and other tropical regions of Mexico and Central America. In South America, arboreal dung beetles are more diverse and include these and other dung beetle species associated with monkeys. Several dung beetle species of the genus Onthophagus have been reported in association with African monkeys. In India, several studies report a wide variety of dung beetle species associated with monkeys. In Australia and New Guinea, only some species of Macropocopris are described as being associated with arboreal monkeys, but in Borneo, several dung beetle species have been observed associated with arboreal monkeys, mostly in managed forests. In Madagascar, Arachnoides gandi is the only beetle species reported in trees. We need to formulate a systematic and comparative methodology to understand better how arboreal beetles search for food, where the food is located, and how brood balls are made, how male-female pairs meet and nest, and how they contribute to arboreal dung recycling

Composition, richness and abundance of Coleoptera associated to semideciduous forests and ruderal vegetation in Sierra del Rosario, Cuba

En tres bosques semideciduos y en tres tipos de vegetación ruderal del Área Protegida de Recursos Manejados Mil Cumbres (Sierra del Rosario, Pinar del Río, Cuba), se analizan las comunidades de coleópteros y se las compara respecto a la composición, riqueza, abundancia, diversidad, equitatividad, ordenación y complementariedad. La composición de coleópteros conocida hasta el momento es de 166 especies, incluidas en 75 géneros y 34 familias. La vegetación ruderal presentaó mayor riqueza y abundancia que los bosques semideciduos. El bosque y la vegetación ruderal de Pan de Guajaibón exhibieron los valores más altos de riqueza, abundancia y número de especies únicas. Ambas formaciones vegetales de Sierra Chiquita presentaron la mayor diversidad y equitatividad. Las comunidades de coleópteros más afines estaban entre los bosques y entre la vegetaciones ruderales en Forneguera y Pan de Guajaibón. Cada bosque y tipo de vegetación ruderal presentaba especies exclusivas.In three semideciduous forests and in three types of ruderal vegetation within the Mil Cumbres Protected Area of Managed Resources (Sierra del Rosario, Pinar del Río, Cuba), the beetle communities were analyzed and compared for composition, richness, abundance, diversity, equitability, ordination and complementarity. A total of 166 species of 75 genera and 34 families were recorded. Ruderal vegetation showed higher values of richness and abundance than the semideciduous forests. The forest and ruderal vegetation of Pan de Guajaibón showed the highest values of species richness, abundance and number of unique species. Both plant communities of Sierra Chiquita presented the highest diversity and equitability values. The most similar beetle communities were between forests and between ruderal vegetation types at Forneguera and Pan de Guajaibón. Each forest and ruderal vegetation type had exclusive species

Seasonal variation of <em>Microcystis aeruginosa</em> and factors related to blooms in a deep warm monomictic lake in Mexico

The occurrence of cyanobacterial blooms has increased globally over the last decades, with the combined effect of climate change and eutrophication as its main drivers. The seasonal dynamic of cyanobacterial blooms is a well-known phenomenon in lakes and reservoirs in temperate zones. Nevertheless, in the tropics, most studies have been performed in shallow and artificial lakes; therefore, the seasonal dynamic of cyanobacterial blooms in deep and eutrophic tropical lakes is still under research. We studied the seasonal variation of the phytoplankton community and the factors associated with Microcystis aeruginosa blooms along the water column of Lake Alberca de Tacámbaro, a warm monomictic crater lake located in Mexico, during 2018 and 2019. According to previous studies performed in 2006 and 2010, this lake was mesotrophic-eutrophic, with Chlorophyta and Bacillariophyta as the dominant groups of the phytoplankton community. During 2018 and 2019, the lake was eutrophic and occasionally, hypertrophic, a phenomenon likely associated with the increase of farmland area around the lake. The dominant species was M. aeruginosa, forming blooms from the surface to 10 m depth in winter, in the hypolimnion in spring and summer, and along the full water column in autumn. These findings suggest that M. aeruginosa in Lake Alberca de Tacámbaro displays seasonal and spatial population dynamics. Total phosphorus, dissolved inorganic nitrogen, water temperature and photosynthetically active radiation were the environmental factors related to M. aeruginosa blooms. Our results suggest that the changes in the structure of the phytoplankton community through time, and M. aeruginosa blooms in Lake Alberca de Tacámbaro, are mainly related to changes in land use from forest to farmland in areas adjacent to the lake, which promoted its eutrophication in the last years through runoffs. Comparative studies with other deep and eutrophic lakes will allow us to gain a deeper understanding of the dynamic of cyanobacterial blooms in natural and artificial water reservoirs strongly stressed by human activities

Influence of phylogenetic, environmental, and behavioral factors on the gut bacterial community structure of dung beetles (Scarabaeidae: Scarabaeinae) in a Neotropical Biosphere Reserve

Gut bacteria help dung beetles metabolize nutrients contained and synthesize those unavailable in their food, depending on the ecological scenario in which they develop. However, less is known about the influence of environmental and behavioral factors on the taxonomic composition of bacterial gut communities in Scarabaeinae beetles. To address this research topic, we analyzed 13 tropical dung beetle species in the Los Tuxtlas Biosphere Reserve, Mexico, to understand how the beetle tribe, habitat, food preference, food relocation, and parental care influence the composition of gut bacterial communities. We found that the beetle tribe is the primary factor impacting the taxonomic composition of gut bacterial communities. Among them, Deltochilini displayed the highest variability in diversity due to the different combinations of habitat and food preferences among its species. On the other hand, the other tribes studied did not exhibit such variable combinations. Habitat emerged as the second most influential factor, with forest-dwelling beetles displaying higher diversity. This can be attributed to the heterogeneous environments within tropical forests, which offer a greater diversity of food resources. In contrast, grassland beetles, living in more homogeneous environments and relying on cow feces as their main food source, exhibited lower diversity. Our findings suggest a correlation between bacterial diversity and food resource availability in complex habitats, such as tropical forests, which offer a wider array of food sources compared to simpler environments like grasslands

Evolutionary history and diversity in the ball roller beetle Canthon cyanellus

To understand the evolutionary history of species, it is necessary to know the mechanisms for reproductive isolation, divergence-time between populations, and the relative action of the evolutionary forces (e.g., mutation, genetic drift, gene flow) within and between populations of the same, or closely related species. Although Canthon is one of the more diverse genera of neotropical beetles, insufficient research has been done to comprehend the divergent patterns that explain its speciation process. The absence of diagnostic morphological characters and the wide geographic variation of qualitative traits in Scarabaeinae obscures species delimitation, genealogical limits between populations, and its taxonomy. Canthon cyanellus is one of the best-known species in ecological and evolutionary aspects. It is a widely distributed species in the tropical forests of America. Also, the current deforestation has facilitated its incursion into open areas. Individuals from different populations have similar morphological characters but show wide variation in body color throughout their distribution, which makes it difficult to delimit the subspecies that comprise it. Recently, studies have been carried out to elucidate the pre-and postzygotic isolation mechanisms between populations and the historical biogeographical processes favoring cladogenesis events during the Pleistocene. Morphological variation of the male genitalia does not correspond to the phylogeographic structure. However, the morphological differences in one of the pieces of the endophallic sclerites have allowed a preliminary delimitation of some genetically differentiated clades. Finally, we consider that the joint analysis of traditional morphological taxonomy and phylogeography is important to understand the speciation process in the C. cyanellus complex

Effects of land use on water quality and Ceriodaphnia dubia reproduction

This study evaluated the effect of water quality of streams from micro-watersheds with different land use (cloud forest, coffee plantation, pasture and under urban influence) during the dry and rainy seasons, lying within the upper watershed of the La Antigua river in Veracruz, Mexico. Water characteristics were measured and laboratory subchronic toxicity tests were performed to evaluate average accumulated progeny, broods per female, and non-reproductive females of Ceriodaphnia dubia. The cloud forest contained chemically undisturbed streams, while the lowest levels of chemical alteration were detected in pasture streams: low fecundity of C. dubia was observed in both types of streams. The most disturbed streams were those associated with coffee plantations and under urban influence, which resulted in enhanced C. dubia fecundity; however, the highest chemical disturbance, found in a stream with urban influence, led to reproduction suppression in the dry season. The most favorable conditions for reproduction were provided by nutrient and probably organic enrichment in streams associated with urban environments and coffee plantations, while in cloud forest and pasture streams, the natural, and close to natural water chemistry caused a reduction in fecundity. Female fecundity was higher during the rainy season

Phylogeographic structure of Canthon cyanellus (Coleoptera: Scarabaeidae), a Neotropical dung beetle in the Mexican Transition Zone: Insights on its origin and the impacts of Pleistocene climatic fluctuations on population dynamics

Canthon cyanellus is a roller dung beetle with a wide distribution range in the tropical forests of the New World. In Mexico, it inhabits the Pacific and the Gulf coasts, the Yucatan Peninsula and the south mainly in the State of Chiapas. This species shows a wide geographical variation in cuticle color, which has been used as defining trait for subspecies. In this study we analyzed the phylogeographic and demographic history of the Mexican populations of C. cyanellus using DNA sequences of the nuclear ITS2, and the mitochondrial COI and 16S genes. We found that not all the current valid subspecies are supported by the molecular analysis. The populations are genetically and geographically structured in five lineages. The diversification events that gave origin to the main lineages within this species complex occurred during the Pleistocine in a time range of 1.63–0.91 Myr. The demographic history of these lineages suggests post-glacial expansions toward the middle and the end of the Pleistocene. The combined data of mitochondrial and nuclear DNA suggest that the phylogeographic structure and demographic history of the C. cyanellus populations are the result of: the geological and volcanic activity that occurred from the end of the Pliocene to the Pleistocene; and the contraction and expansion of tropical forests due to the glacial and inter-glacial cycles during the Pleistocene. Landscape changes derived from historical events have affected the demographic history of the populations of this species. The results presented here point to the need to review the taxonomic status and delimitation of the lineages encompassed in the Canthon cyanellus complex.This work was financial supported by the Consejo Nacional de Ciencia y Tecnología, México (CONACyT, grant number CB-168373, 257039). This paper constitutes a partial fulfilment of the Graduate Program in Biodiversidad: Conservación y Gestión de las Especies y sus Hábitat of the Centro Iberoamericano de la Biodiversidad (CIBIO), Universidad de Alicante, España

The Role of Body Size and Shape in Understanding Competitive Interactions within a Community of Neotropical Dung Beetles

Geometric morphometrics is helpful for understanding how body size and body shape influence the strength of inter-specific competitive interactions in a community. Dung beetles, characterized by their use of decomposing organic material, provide a useful model for understanding the structuring of ecological communities and the role of competition based on their size and morphology. The relationship between body size and shape in a dung beetle community from the Atlantic Forest in Serra do Japi, Brazil was analyzed for 39 species. Fifteen anatomical landmarks on three-dimensional Cartesian coordinates were used to describe both the shape and the size of the body of each species on the basis of the centroid located along homologous points in all of the species. The first vector of a principal components analysis explained 38.5% of the morphological variation among species, and represents a gradient of body shape from elongated, flattened bodies with narrow abdomen to rounded or convex bodies. The second component explained 17.8% of the remaining variation in body shape, which goes from species with an abdomen that is larger than the elytra to species with constricted abdomens and large elytra. The relationship between body size and shape was analyzed separately for diurnal and nocturnal species. In both guilds not only were there differences in body size, but also in body shape, suggesting a reduction in their level of competition