Felipe Barragán

Negative impacts of human land use on dung beetle functional diversity.

The loss of biodiversity caused by human activity is assumed to alter ecosystem functioning. However our understanding of the magnitude of the effect of these changes on functional diversity and their impact on the dynamics of ecological processes is still limited. We analyzed the functional diversity of copro-necrophagous beetles under different conditions of land use in three Mexican biosphere reserves. In Montes Azules pastures, forest fragments and continuous rainforest were analyzed, in Los Tuxtlas rainforest fragments of different sizes were analyzed and in Barranca de Metztitlán two types of xerophile scrub with different degrees of disturbance from grazing were analyzed. We assigned dung beetle species to functional groups based on food relocation, beetle size, daily activity period and food preferences, and as measures of functional diversity we used estimates based on multivariate methods. In Montes Azules functional richness was lower in the pastures than in continuous rainforest and rainforest fragments, but fragments and continuous forest include functionally redundant species. In small rainforest fragments (<5 ha) in Los Tuxtlas, dung beetle functional richness was lower than in large rainforest fragments (>20 ha). Functional evenness and functional dispersion did not vary among habitat types or fragment size in these reserves. In contrast, in Metztitlán, functional richness and functional dispersion were different among the vegetation types, but differences were not related to the degree of disturbance by grazing. More redundant species were found in submontane than in crassicaule scrub. For the first time, a decrease in the functional diversity in communities of copro-necrophagous beetles resulting from changes in land use is documented, the potential implications for ecosystem functioning are discussed and a series of variables that could improve the evaluation of functional diversity for this biological group is proposed.

Reanálisis de la diversidad alfa: alternativas para interpretar y comparar información sobre comunidades ecológicas.

El indice de entropia de Shannon y otras medidas de complejidad se utilizan frecuentemente para evaluar la diversidad de especies en comunidades ecologicas, aun cuando su comprension es dificil y sus valores no son comparables. En este trabajo se muestra que los numeros efectivos de especies (medidas de diversidad verdadera) permiten obtener una interpretacion intuitiva y facilmente comparable de la diversidad de especies. Se ejemplifica su uso reanalizando los datos de 4 trabajos publicados en la Revista Mexicana de Biodiversidad (realizados en distintos ecosistemas y regiones de Mexico, con distinta resolucion taxonomica y enfocados en distintos grupos biologicos). Se utilizan modelos de estimacion en los que se considera que las muestras son representaciones incompletas de las comunidades. Se explica tambien la manera en que las medidas de diversidad de distinto orden incorporan a las especies segun su abundancia en la comunidad. Los resultados obtenidos pueden resultar de especial interes cuando los valores de diversidad se utilizan para proponer medidas para el manejo de recursos y la conservacion biologica.

NEW RECORDS OF THE ENDANGERED TEHUANTEPEC JACKRABBIT (LEPUS FLAVIGULARIS) FROM OAXACA, MEXICO

Abstract We obtained new records of the Tehuantepec jackrabbit, Lepus flavigularis, in the state of Oaxaca, México. The records represent 3 new populations of L. flavigularis in the southern part of the Isthmus of Tehuantepec. The total area where the new records of L. flavigularis occurred is 67 km2. It is necessary to conduct additional studies to obtain details of the actual distribution of the endangered L. flavigularis and recommend actions for its conservation.

Bat and Rodent Diversity in a Fragmented Landscape on the Isthmus of Tehuantepec, Oaxaca, Mexico

We assessed the patterns of diversity, richness, abundance, and dissimilarity in rodent and bat communities for four sites on the Isthmus of Tehuantepec in Oaxaca, Mexico, an important region given the enormous number of endemic Neotropical species. The main objective was to examine rodent and bat community parameters relative to habitat diversity and human habitat disturbance in a fragmented landscape. We captured 1,133 individuals of 13 rodent species and 26 bat species from January to August 2006. The site (landscape unit) with greatest habitat diversity also had the highest diversity of rodents. Species dissimilarity was low between sites that had similar degrees of human disturbance. For rodents, species dissimilarity between habitats on the Isthmus of Tehuantepec landscape was generally high; therefore, the species are not distributed evenly across the entire landscape. For bats, the degree of species dissimilarity between the different habitats of the landscape was low. The distribution of bat species across the landscape is a reflection of their high vagility and the spatial structure of the landscape. The results show the importance of a diversity of habitats to the patterns of richness, abundance, and dissimilarity of mammals in the study area.

The Role of Canthon humectus hidalgoensis (Bates) (Coleoptera: Scarabaeidae) in Dung Removal from a Cattle Pasture

Centro de Investigaciones Biologicas, Instituto de Ciencias Basicas e IngenieriaUniversidad Autonoma del Estado de Hidalgo. Carretera Pachuca-Tulancingo km 4.5C.P. 42184, Mineral de la Reforma, Hidalgo, MEXICOcmoreno@uaeh.edu.mxAs rearing livestock spread in Mexico, cattledung became the main alternative food source fordung beetles in pastures (Amezquita and Favila2010). The role of these beetles is fundamental toecosystem functioning and recovery, given theircontribution to several ecological processes includ-ing dung removal, nutrient cycling, secondary seeddispersal, and soil aeration (Nichols et al. 2008). Inthe cattle pastures of the state of Hidalgo, Mexico,Canthon humectus(Say)isoneofthemostcommondung beetle species. In the Barranca de MeztitlanBiosphereReserve,thesubspecies Canthonhumectushidalgoensis (Bates) is a generalist dung feeder thatrepresents up to 94% of the total number of dungbeetles(Verduetal.2007),sostudyingthebehaviorof this beetle will allow us to describe its possibleimpact on ecological processes, especially that ofdung removal in pastures.Canthonhumectushidalgoensisisadiurnalbeetlethat makes dung balls and rolls them from the cowpat to another site. Lone beetles do this to feed andmatingpairsdoitfornesting.Fornesting,theballisrolled by the male who pulls the ball with his hindlegs. Thefemale isattractedby hispheromones andtakes her place atop the ball to help the male roll it.The male buries the dung ball in the nesting site,and the female transforms it into a brood ball(Moron 2004). This species is common in xerophi-lous scrublands, in forests ranging from 1,400 to2,000 m above sea level, as well as in open and iso-lated livestock areas (Halffter et al. 2011).The purposeofthisstudy was todescribe someofthe characteristics of the dung removal process per-formed by individuals and pairs (male and female)of C. humectus hidalgoensis. We measured: 1) thelinear distance (m) from the source and duration(minutes) of dung rolling; 2) the size (mm) andweight (g) of the dung ball; and 3) the abundanceand density of this species in order to estimate itsimpact on the ecosystem. The study was done innorthern Hidalgo, Mexico, in the vicinity of Jacala(21°1′1.17″ N 99°12′2.35″ W). The area is locatedin the Sierra Madre Oriental mountain range, at1,376 m elevation. Native vegetation is temperatemixed forest dominated byJuniperus flaccidaSchltdl., Juniperus deppeana Steud., and Cupressussp. (all Cupressaceae). Mean annual temperature is17.8 °C, and the rainy season occurs from June toSeptember. The study site is a 44.37-ha ranch, ofwhich 60% preserves temperate forest remnants.The rest of the property has been induced pasturefor livestock for at least the last 38 years. During thesampling period, there were approximately 20 headof cattle and 65 sheep on the property. We stud-ied the dung relocation behavior of C. humectushidalgoensis in the cattle pasture during 10 daysin July 2010. At this site, the mean length ofC. humectus hidalgoensis was 10.11 mm (n =50,range = 7.8–16.1 mm) and mean weight was 0.18 g(n = 50, range = 0.06–0.8 g).To determine the linear displacement of dungand the total rolling time, we followed individualsfrom the source cow pat to the burying site. Displa-cement trajectories were complex, changing direc-tions, but mean linear distance from the source tothe burying site was 2.6 m (n = 24, range = 0.28–9.65 m). Ball rolling lasted on average 23.6 minfrom departure from the cow pat until the buryingprocessbegan(n=25,range=5–65minutes;Fig.1a).This suggests that this beetle species may be remov-ing each dung pat, which is approximately 0.10 m

Raptor Functional Diversity in Scrubland-Agricultural Landscapes of Northern-Central-Mexican Dryland Environments:

Raptor birds have widespread distributions in different environments throughout the planet. Yet, they are highly sensitive to landscape disturbances. We studied raptors in northern-central Mexico at the Highland plateau of San Luis Potosí and Zacatecas, in three landscape types that differed in proportion of agriculture. Our main goal was to determine whether small proportion of agriculture at the landscape level influences species richness, ecological diversity, and functional diversity. We conducted raptor road surveys during 1 year, from April 2015 to February 2016. We registered a total of 332 birds belonging to 14 diurnal raptor species. The most abundant species were Cathartes aura (turkey vulture), Falco sparverius (American kestrel), Caracara cheriway (crested caracara), and Buteo jamaicensis (red-tailed hawk). Three species: Aquila chrysaetos (golden eagle), Pandion haliaetus (osprey), and Falco columbarius (merlin) were exclusively recorded in the less-degraded, scrubland landscapes. However, no significant differences on average diversity were found between landscape types. Contrastingly, scrubland landscapes had the highest average functional diversity, followed by mixed landscapes, and then by agricultural landscapes, with significant differences in functional diversity between scrubland and agricultural landscapes. Overall, observed species richness in the study area formed four functional groups. These groups change and loose species as proportion of agriculture in the landscape progressively increases. The results suggested that the contribution of species richness to functional diversity, both for scrubland landscapes, which have the greatest functional diversity, and agricultural landscapes, which hold the smallest functional diversity, is important because there is substantial functional redundancy among landscape types.