Posgrado

Information on the spatial ecology of the Tehuantepec jackrabbit (Lepus fl avigularis) is important for developing management strategies to preserve it in its habitat. We radio-collared and monitored 60 jackrabbits from May 2006 to April 2008. We estimated annual and seasonal home ranges and core areas by using the fi xed-kernel isopleth to 95% and 50% of confi dence, respectively. This jackrabbit showed a highly variable seasonal home range: 1.13 ha to 152.61 ha for females and 0.20 ha to 71.87 ha for males. Annual and seasonal home ranges and core areas of females were signifi cantly wider than male home ranges. There was considerable overlap of ranges within and between sexes, with the home range of each jackrabbit overlapping with the ranges of 1 to 46 other individuals. Home range and overlap analysis confi rms that the Tehuantepec jackrabbit is a polygamous and non-territorial species. Conservation of savannas and grassy dunes is indispensable to assure the survival of the species.

The Oaxacan Spiny-tailed Iguana Ctenosaura oaxacana is a restricted species to the Isthmus of Tehuantepec in Southern Oaxaca, Mexico. This reptile is one of the less known iguanid species. We censustracked a population in the South of Niltepec, Oaxaca, Mexico from May 2010 to April 2011. Throughout one year, a total of 10 line transects were situated and recorded in the study area to determine relative abundance and density, and habitat type use (dry forest, Nanchal, grassland, riparian vegetation, and mangrove) by the species. This study reports a new C. oaxacana population on the Southeastern limit of species range. Although this species has a very restricted distribution and is in danger of extinction, C. oaxacana has a high population density when compared to other Ctenosaura species. A total of 108 individuals were recorded throughout the study. Dry forest (33.75ind/ha) and Nanchal (18.75ind/ha) were the habitats with higher densities. Comparisons between habitat types showed no significant differences between dry forest and Nanchal (W=15, p=0.0808). Results between seasons were similar. The Oaxacan Spiny tailed Iguana preferred first the dry forest, and then Nanchal, while avoided grassland, riparian vegetation, and mangroves. There was no difference in habitat use between males and females. Mean perch heights were 1.23±0.32 (n=30) in Nanchal, 2.11±0.30 (n=9) in grassland, 1.90±0.56 (n=54) in dry forest, 1.91±0.28 (n=9) in mangrove and 2.30±0.37 (n=6) in riparian vegetation. Species observed as refuge and perch were B. crassifolia (Nanchal); C. alata (grassland); Tabebuia sp., Genipa americana, G. sepium, Acacia sp., Ficus sp. and Haematoxylon sp. (dry forest); G. sepium, Acacia sp. and Guazuma ulmifolia (riparian vegetation); and C. erecta (mangrove). Live trees hollows and branches were used by species. Main threats to the species are excessive hunting and habitat loss. Furthermore, grassland fires are still common in the study area during the dry season, which can result in habitat loss and territorial displacement of individuals. Rev. Biol. Trop. 60 (4): 1613-1619. Epub 2012 December 01.

The persistence of reptile populations in a specific location is influenced by individuals' capacity to regulate their body temperatures, among other factors. Anthropogenic climate change may pose a risk to the survival of ectothermic animals due to their dependence on external heat sources to thermoregulate. In this study, we calculated indices of thermal habitat quality, thermoregulatory precision, and thermoregulatory effectiveness for the endemic spiny-tailed iguana Ctenosaura oaxacana. We evaluated these indices and the thermoregulatory behavior of the iguanas in the four types of vegetation that provide the most favorable conditions for thermoregulation. We also performed our experiments during both the wet and dry seasons to capture the full range of thermal conditions available to C. oaxacana over the course of a year. Finally, we evaluated the potential niche for the iguana in the years 2020, 2050, and 2080. Thermoregulation depends on both seasonal and environmental factors in this species. We found that thermoregulation effectiveness in both wet and dry seasons depends not only on the thermal conditions of the immediate environment, but also on the cover vegetation and habitat structure available across the range of habitats the species uses. Thus, heterogeneous habitats with dispersed vegetation may be most suitable for this species' thermoregulatory strategy. Likewise, niche modeling results suggested that suitable habitat for our study species may continue to be available for the next few decades, despite global warming tendencies, as long as cover vegetation remains unaltered. Our results suggest that thermoregulation is a complex process that cannot be generalized for all ectothermic species inhabiting a given region. We also found that temperature changes are not the only factor one must consider when estimating the risk of species loss. To understand the necessary thermal conditions and extinction risk for any ectothermic species, it is necessary to focus studies on the species' general ecology.

Oaxaca hosts one of the greatest biodiversity in México, occupying first place in avian diversity compared to other regions of the country. However, the area is undergoing serious problems such as high deforestation rates, soil erosion and over exploitation and extinction of species. These factors have all contributed to the current loss of biodiversity. Also, biological inventories are still incomplete. One of the least explored sites is the semiarid zone of Tehuantepec isthmus, around the locality of Santa Maria del Mar, Oaxaca, México. The area includes floodable grasslands, mangrove areas and dry forest, providing a range of potential habitats for different species. Our objective was to evaluate the effect of temporal lakes on spatial and temporal composition of the avifauna in Santa Maria del Mar, in order to generate information regarding this group within the region and the state, and to understand the importance of flood areas for resident and transitory birds. We conducted 12 avifauna surveys between July 2006 and June 2008, and established two transects of 2km length in each of four habitat types (beach, grassland, dry forest, and mangrove). We found a total of 75 species, corresponding to 16 orders and 30 families. Within an area of 26km 2 , we significantly found 10.1% of the total number of bird species recorded for the entire state, and 6.6% of the total reported in Mexico. The families most represented were: Ardeidae, Laridae and Scolopacidae. Over the entire study period, dry forest was the most diverse habitat; followed by mangrove, grassland and the beach. Of all the species recorded, 38.6% were found at the edge or in the temporal lakes. We found a significant difference in species composition between seasons in the grassland, but no difference in the other habitats. Our results showed a significant effect of temporary lakes on avian diversity during the wet season; it also demonstrated the importance of grassland conservation given its relevance for presence of waterbirds. We suggested a continued and more intense monitoring; and proposed the designation of the area as an important Conservation Bird Area (AiCA). Rev. Biol. Trop. 62 (4): 1523-1533. Epub 2014 December 01.

La primera fase del libro presenta diferentes enfoques que contribuyen a la formulación de marcos de análisis que integran a las ciencias naturales con las ciencias sociales. Durante su lectura se transita por construcciones teórico-conceptuales en donde confluyen disciplinas como la ecología, biología de la conservación, geografía, antropología, sociología, agronomía, veterinaria y medicina de la conservación. En la segunda parte se presenta un interesante panorama de estudios sobre conservación y manejo de fauna silvestre en los tres estados del Sur de México que coinciden en ser los más marginados y los más pobres del país: Guerrero, Oaxaca y Chiapas. En este sentido, un elemento común en estos artículos es la contradicción (no exenta de conflictos de diversa índole y magnitud), entre la conservación de la biodiversidad y el bienestar de las poblaciones locales que conviven con y usan dicha biodiversidad.

2 y Mayra de La Paz-Cuevas 3 The biological knowledge, current distribution and conservation status of the species of jackrabbits (Lepus) in risk category distributed in islands of Baja California Sur, Mexico is very useful to take specific actions for its management and conservation. The objective of this work was to spread recent results on the actual state that keep the populations from two species of Lepus with presence in the Islands Margarita and Magdalena (L. californicus magdalenae), Carmen (L. c. sheldoni), and Espiritu Santo (L. insularis). We analyzed their distribution, density, habitat, associate fauna, and human impact in their populations. Additionally, we proposed new risk categories for the species and subspecies of jackrabbits following the criteria of the method of evaluation of extinction risk for the wild species in Mexico (MER), and were included data on their behavior, food habits and signs of reproductive activity.

En México, las políticas públicas orientadas a la conservación de la biodiversidad han acentuado la problemática ambiental y social. La situación actual de peligro de extinción que enfrenta la liebre de Tehuantepec (Lepus flavigularis) y la pobreza que experimentan las comunidades indígenas Ikoots (huave) y Binnizá, asentadas en el área de distribución de la liebre, al sur de Oaxaca, son un claro ejemplo de ello. Por un lado, la liebre no ha sido adecuadamente valorada como elemento de desarrollo sostenible en las políticas públicas nacionales, estatales,y locales, por lo que no se ha desarrollado un programa definido que oriente y organice a largo plazo la conservación de la misma, llevando a la dispersión de iniciativas, proyectos y estrategias de mediano y largo plazos, a la nula participación de las comunidades en la toma de decisiones, a la escasez de estudios prácticos, a la falta de capacitación, al fomento de prácticas productivas incompatibles con la conservación, a la limi...

La degradación y pérdida de hábitat ha puesto en peligro de desaparecer a cientos de especies en nuestro país. El estado de Guerrero no es la excepción. Dicha pérdida de hábitat se ve además exacerbada por las condiciones de marginación de la población y los constantes conflictos fauna-seres humanos. Entre los mamíferos, los felinos son probablemente el grupo más carismático, algunos de sus miembros, como el puma y el jaguar, se encuentran en grave peligro pues también son cazados al ser considerados una amenaza para los habitantes de las comunidades y su patrimonio. El objetivo de este proyecto fue determinar la presencia de felinos silvestres en la región de los Pueblos Santos, Guerrero. Para ello se desarrollaron dos metodologías, la primera consistió en la realización de entrevistas abiertas con actores clave dentro de las comunidades, mientras que la segunda consistió en el establecimiento de seis transectos de longitud y ancho variable. A lo largo de dichos transectos se regis...

It has been documented that certain types of shade coffee plantations have both biodiversity levels similar to natural forest and high concentrations of wintering migratory bird species. These findings have triggered a campaign to promote shade coffee as a means of protecting Neotropical migratory birds. Bird censuses conducted in the El Triunfo Biosphere reserve in southernMexico have confirmed that shade coffee plantations may have bird diversity levels similar to, or higher than, natural forest. However, coffee and forest differed in species composition. Species with a high sensitivity to disturbance were significantly more diverse and abundant in primary ecosystems. Neotropical migratory birds, granivorous and omnivorous species were more abundant in disturbed habitats. Insectivorous bird species were less abundant only in shaded monoculture. Foraging generalists and species that prefer the upper foraging stratum were more abundant in disturbed habitats, while a decline in low and middle strata foragers was found there. Findings suggests that shade coffee may be beneficial for generalist species (including several migratory species), but poor for forest specialists. Although shade coffee plantations may play an important role in maintaining local biodiversity, and as buffer areas for forest patches, promotion of shade coffee may lead to the transformation of forest into shade coffee, with the consequent loss of forest species.

In 1998, storms related to Hurricane Isis caused extensive gaps in the cloud forest of El Triunfo Biosphere Reserve in Chiapas, Mexico, where severe storms are infrequent. We examined how this disturbance affected bird species composition. Species richness and composition were similar both between pre- and post-disturbance forest and between newly created gaps and plots that remained forested after the hurricane. However, differences in response guilds were greater between pre- and post-disturbance plots than between forest plots with gaps after disturbance. Granivorous, omnivorous, and terrestrial species were more abundant before the hurricane, whereas insectivorous, midstory, and generalist foragers were more abundant after the hurricane. In addition, species with high sensitivity to disturbance were more abundant in the pre-disturbance forest, while low sensitivity species were more abundant after disturbance. In the post-disturbance forest, insectivorous species were most abundant in gaps and terrestrial-canopy foragers were most abundant in forest plots. Permanently open areas had significantly lower species richness, but had lowland generalist and second-growth species not present in the cloud forest. Results suggest that changes in species composition were not limited to the newly created gaps, but also affected the whole forest. The decline of high sensitivity species after disturbance supports the hypothesis that disturbance negatively affects specialists and benefits generalist species. Although there is evidence that natural communities tend to return to pre-disturbance conditions, changes in community structure could be aggravated if recurrent hurricanes occur before succession takes place.

Studies have documented biodiversity losses due to intensification of coffee management (reduction in canopy richness and complexity). Nevertheless, questions remain regarding relative sensitivity of different taxa, habitat specialists, and functional groups, and whether implications for biodiversity conservation vary across regions.We quantitatively reviewed data fromant, bird, and tree biodiversity studies in coffee agroecosystems to address the following questions: Does species richness decline with intensification or with individual vegetation characteristics? Are there significant losses of species richness in coffee-management systems compared with forests? Is species loss greater for forest species or for particular functional groups? and Are ants or birds more strongly affected by intensification? Across studies, ant and bird richness declined with management intensification and with changes in vegetation. Species richness of all ants and birds and of forest ant and bird species was lower in most coffee agroecosystems than in forests, but rustic coffee (grown under native forest canopies) had equal or greater ant and bird richness than nearby forests. Sun coffee (grown without canopy trees) sustained the highest species losses, and species loss of forest ant, bird, and tree species increased with management intensity. Losses of ant and bird species were similar, although losses of forest ants were more drastic in rustic coffee. Richness of migratory birds and of birds that forage across vegetation strata was less affected by intensification than richness of resident, canopy, and understory bird species. Rustic farms protected more species than other coffee systems, and loss of species depended greatly on habitat specialization and functional traits. We recommend that forest be protected, rustic coffee be promoted, and intensive coffee farms be restored by augmenting native tree density and richness and allowing growth of epiphytes.We also recommend that future research focus on potential trade-offs between biodiversity conservation and farmer livelihoods stemming from coffee production.

Municipal-level inventories of the avifauna and its application to conservation: the case of Zacapoaxtla, Puebla, Mexico. – Bird Inventories at the municipal-level could improve the selection of priority areas in conservation. Based on an update of the avifauna of Zacapoaxtla Municipality, Puebla, Mexico, we used vegetation type and land use within the municipality to analyze bird species’ richness, endemism, and species at risk. We also examined the general distribution patterns and described birds’ seasonality. The highest species richness, and the highest numbers of endemic, threatened, and exclusive species were found in cloud forest; followed, in descending order, by pine forest, pine-oak forest, temporary agriculture and cultivated grasslands. Based on this information, we propose priority areas for bird preservation within the municipality and we discussed the role of inventories at this scale as a strategy for conservation.

It has been documented that certain types of shade coffee plantations have both biodiversity levels similar to natural forest and high concentrations of wintering migratory bird species. These findings have triggered a campaign to promote shade coffee as a means of protecting Neotropical migratory birds. Bird censuses conducted in the El Triunfo Biosphere reserve in southern Mexico have confirmed that shade coffee plantations may have bird diversity levels similar to, or higher than, natural forest. However, coffee and forest differed in species composition. Species with a high sensitivity to disturbance were significantly more diverse and abundant in primary ecosystems. Neotropical migratory birds, granivorous and omnivorous species were more abundant in disturbed habitats. Insectivorous bird species were less abundant only in shaded monoculture. Foraging generalists and species that prefer the upper foraging stratum were more abundant in disturbed habitats, while a decline in low and middle strata foragers was found there. Findings suggests that shade coffee may be beneficial for generalist species (including several migratory species), but poor for forest specialists. Although shade coffee plantations may play an important role in maintaining local biodiversity, and as buffer areas for forest patches, promotion of shade coffee may lead to the transformation of forest into shade coffee, with the consequent loss of forest species.

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.

Sex allocation theory predicts that reproducing individuals will increase their
fitness by facultatively adjusting their relative investment towards the rarer
sex in response to population shifts in operational sex ratio (OSR). The
evolution of facultative manipulation of sex ratio depends on the ability of
the parents to track the conditions favouring skewed sex allocation and on the
mechanism controlling sex allocation. In animals, which have well-developed
sensorial mechanisms, facultative adjustment of sex ratios has been demonstrated
on many occasions. In this paper, we show that plants have
mechanisms that allow them to evaluate the population OSR. We simulated
three different conditions of population OSR by manipulating the amount of
pollen received by the female flowers of a monoecious herb, and examined the
effect of this treatment on the allocation to male vs. female flowers. A shortage
of pollen on the stigmas resulted in a more male-skewed sex allocation,
whereas plants that experienced a relatively pollen rich environment tended
to produce a more female-skewed sex allocation pattern. Our results for
Begonia gracilis demonstrate that the individuals of this species are able to
respond to the levels of pollination intensity experienced by their female
flowers and adjust their patterns of sex allocation in accordance to the
expectations of sex allocation theory.

In species with broad distribution, geographic variation could be associated to particular environmental factors that may affect plant reproduction. In dimorphic
species, environmental factors may influence evolutionary processes governing sex ratio variation and floral traits evolution. Kallstroemia grandiflora is an annual insectpollinated
gynodioecious herb with broad distribution from the Sonoran desert to the semiarid west coast of Mexico. In this study, we explored if female frequency
increases in harsh environments and the associated changes in floral morphology in female and hermaphrodite plants. We selected 23 populations along the pacific
coast of Mexico where we estimated female frequency and in eight of them we also measured flower size in hermaphrodite and female plants. The average decrease in
precipitation was correlated with the increase in female frequency, and a reduction in the flower size of hermaphrodite plants. Our results support the idea that harsh
environments may influence female frequency, but also flower size and possibly breeding system evolution.

This research was carried out in a degraded pasture at Selva Lacandona tropical rain forest in Chiapas, Mexico. During a whole year weeding and fertilization effects were assessed on the seedling performance of six native tree species measuring survival and growth. From the dry season onwards the survival probability of the seedlings rise under grass covering (without weeding treatment) both for light demanding and shadow tolerating species. Helophytic seedlings, Ceiba pentandra, Schizolobium parahyba and Swietenia macrophylla had higher levels of survival and growth than shadow tolerating species, Brosimum alicastrum, Calophyllum brasiliense and Ormosia schippii. Relative growth rate (TRC) in height and diameter changed significantly for the simple effect of weeding and for the species itself. The simple effect of weeding indicated a higher growth on height and diameter of the plants under weeding treatment. We did not observe any significant effects of the fertilization on plants performance. The effect of the species was the most consistent factor in explaining variances in the three response variables, meaning that the tree species under investigation had specific survival and growth trajectories which lie aside the effect of the treatments.