The Collection and Sale of Wild Mushrooms in a Community of Tlaxcala,Mexico

The Collection and Sale of Wild Mushrooms in a Community of Tlaxcala, Mexico. In this paper, we characterize the harvest and sale of wild mushrooms in Javier Mina (Tlaxcala state, Mexico) based on observations made during visits to that community during the rainy seasons of 1995 and 2001. While there, we visited the forests with various families of mushroom gatherers and also carried out 16 visits to a local mushroom broker to obtain information on the buying and selling of the mushrooms, including a list of the prices per kilo of the species that are sold commercially. Boletus cf. pinophilus, Lyophyllum cf. decastes, Hebeloma aff. mesophaeum and the Amanita caesarea complex were the highest–priced species, and were those collected in the greatest amounts. Our observations indicate that the gathering of mushrooms, a traditional activity among the people of Javier Mina, contributes, through the sale of the mushrooms, to the income of the community during the rainy season.

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Recolección y venta de hongos silvestres en una comunidad de Tlaxcala, México. Recolección y venta de hongos silvestres en una comunidad de Tlaxcala, México. El objetivo de este trabajo es describir el proceso de recolección y venta de hongos silvestres en Javier Mina, Tlaxcala. Para describir estas actividades se realizaron visitas a los bosques con varias familias recolectoras de hongos durante las épocas de lluvias de 1995 y 2001. Además, se realizaron 16 visitas a un distribuidor local para registrar información con respecto a la compra y venta de los hongos. Se obtuvo un listado de los precios por kilo de los hongos que se comercializan. Boletus cf. pinophilus, Lyophyllum cf. decastes, Hebeloma aff. mesophaeum y Amanita caesarea complex fueron los hongos recolectados en mayor cantidad durante este estudio, mismos que tuvieron los precios más altos de compra–venta. Se concluye que la recolección de hongos es una actividad tradicional para la gente de Javier Mina; sin embargo, la venta de éstos, contribuye a la obtención de ingresos durante la temporada de lluvias.

     

The agroecology of corn production in Tlaxcala,Mexico

The primary components of Tlaxcalan corn agriculture are described, including cropping patterns employed, resource management strategies, and interactions of human and biological factors. Tlaxcalan farmers grow corn in an array of poly-culture and agroforestry designs that result in a series of ecological processes important for insect pest and soil fertility management. Measurements derived from a few selected fields show that trees integrated into cropping systems modify the aerial and soil environment of associated understory corn plants, influencing their growth and yields. With decreasing distance from trees, surface concentrations of most soil nutrients increase. Certain tree species affect corn yields more than others. Arthropod abundance also varies depending on their degree of association with one or more of the vegetational components of the system. Densities of predators and the corn pest Macrodactylussp. depend greatly on the presence and phenology of adjacent alfalfa strips. Although the data were derived from nonreplicated fields, they nevertheless point out some important trends, information that can be used to design new crop associations that will achieve sustained soil fertility and low pest potentials.     

Modeling the interaction of physiological time, seasonal weather patterns, and delayed mating on population dynamics of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae)

The effect of delaying female mating on population growth in codling moth (Cydia pomonella (L.)) was found to act on a physiological time (degree-day) basis and was predictable using a simple quadratic equation. When combined with previous work on degree-day based mortality, we were able to evaluate how the magnitude of population reduction and survival varied between sites, years, and generations at locations in California, Michigan, Pennsylvania and Washington states. In general, reductions in population growth associated with females mating 1–3 days after emergence were greater in warmer areas and during warmer times of the year. In any given year and location, the temperature profiles during peak flight were crucial in determining the population reductions, but over an 11-year period, the average seasonal temperature profile was more important. During the overwintering generation, conditions were relatively mild in all locations and only minor differences were observed in population growth rates between locations. Populations experiencing 1–3 days delay in female mating were reduced 8, 19 and 32 % compared to populations experiencing no delay, respectively. During the first summer generation, population reductions doubled compared to those seen in the overwintering generation. During the second summer flight, reductions in population growth rate at the three cooler locations decreased, while they increased in the warmer California location. Overall, the results show delayed mating can help understand how population growth is related to environmental conditions experienced naturally by insect populations and will help guide studies of the mechanisms of mating disruption, a technique used for pest suppression in agricultural and forest systems.     

Ecological demography: A synthetic focus in evolutionary anthropology

The interests of evolutionary anthropologists, behavioral ecologists, and demographers converge on the ecology of human fertility. Ecological conditions influence the optimum pattern of maternal effort. Patterns of abortion, neglect, and infanticide vary with mothers' ability to invest in their children and children's ability to use that investment. As in most other mammals, the ecology of human fertility varies between the sexes: status and resource control are important for males, whereas reproductive value is crucial for females. In pre-industrial societies, and even in monogamous societies in demographic transition, wealthy men had more children than did poorer men. This correlation, often assumed to have disappeared, persists today, with richer men still having more sexual access than others. Sex differences in the ecology of fertility mean that sex of the offspring, as well as birth order, influences parental investment. Because individual fertility varies with environment, it is not surprising that “natural” (uncontrolled) fertility varies across societies or that demographic transitions proceed locally, with occasional reverses, as individuals strive to maximize their lifetime reproductive success in changing, competitive, conditions.     

Tiller demography in seashore populations of Agrostis stolonifera,Festuca rubra and Poa irrigata

Abstract. The dynamics of tillers in natural populations of three cohabiting perennial grass species, Agrostis stolonifera, Festuca rubra and Poa irrigata (= Poa pratensis ssp. irrigata) were studied for five years in a Baltic seashore meadow. The process of tiller population maintenance was very dynamic. Both birth and death rates of tillers were high, particularly in A stolonifera, and the turnover rate of the populations was high. Recruitment was mainly by vegetative tillers, produced continuously throughout the growing season. The proportion of flowering tillers was low, but varied between years. Considerable year-to-year variation was also found in birth and death rates. Despite this between-year variation and the differences found between species in flowering frequency, pattern of survivorship and tiller longevity, population sizes of the species remained relatively constant.     

Human Tracks from Quaternary Tufa Deposits,Cuatro Cienegas,Coahuila, Mexico

In 1961, two human footprints were excavated from the Cuatro Cienegas region of Coahuila, Mexico, but for decades were not studied scientifically or deposited in any museum. Consequently, knowledge of the locality where they were found was lost. Once the two tracks were relocated they found their way to the Museo del Desierto, Saltillo (Coahuila) where they were placed on display with a tentative label suggesting an early Holocene age (10,000 B.C.). This inference was based only on the known antiquity of humans in the region determined from previous archaeological work and two dated sediment cores close to the footprint site. It was not until 2006 that the presumed footprint discovery site was rediscovered, revealing more than 20 additional well-preserved prints, in at least four trackways representing several different individuals with foot lengths ranging from about 23–27 cm. The tracks include one well-preserved trackway providing step and stride measurements. A poorly preserved cervid trackway and a possible duck footprint have also been identified. The footprints are preserved in hard tufa. Geochemical evidence suggests the tracks were made during periods of increased aridity.     

Reproductive biology of gag in the southern Gulf of Mexico

Aspects of the reproductive biology of gag Mycteroperca microlepis in the southern Gulf of Mexico were studied by following seasonal variations in the gonado‐somatic index and through histological examination of gonads. Gag were collected from inshore and offshore waters of the Campeche Bank, Yucatan, Mexico, between April 1996 and December 2001. This species is a protogynous hermaphrodite, and appeared to be depth‐size distributed. The smallest gag (9–49 cm L _F) collected were all juvenile females, and were caught in inshore waters (1–10 m depth), while the largest (49–116 cm L _F), mainly adult females, males and transitionals, were captured in offshore waters (33–167 m depth). Overall the offshore male to female ratio was female‐biased (1 : 3·3) and differed significantly from unity. The species spawns at depths of c . 50–53 m, from early winter to mid‐spring, with peak spawning activity occurring between January and March. Fifty per cent of females reached first maturity at 72·1 cm L _F. At 103 cm L _F, 50% of sampled females had changed into males. Gag can be considered a monandric species, and sexual transition for this grouper seemed to occur in fish distributed within a narrow size range (85–111 cm L _F). The results are compared with those of other authors for gag stocks from the south‐east Atlantic coast of the U.S.A. and the north‐east Gulf of Mexico.     

Relationship among settling,demography and habitat selection: an approach and a case study

Summary We explore the demographic consequences of site selection by animals on their abundance among habitats. We found that pre and post settling survivorship are important links between the behavioral decisions where to settle and the distribution of a population among habitats. This was demonstrated for 10 generations of the desert isopod, Hemilepistus reaumuri, in three habitats in the Negev Desert, Israel. The populations exhibit low survivorship before settling (12%) and high survivorship (55%) after settling. According to our model this implies high site selection. Theoretical considerations and the case study led us to suggest the following relationship among settling, demography and habitat selection: 1) Individuals search for suitable settling sites to inhabit and reproduce. 2) Their decision where and when to settle is a cost benefit decision. They weigh the benefit of searching for a high quality site against mortality due to increased searching time. 3) The individual's decision to settle determines the pre and post settling survivorship pattern. 4) Survivorship pattern dictates density pattern in time and space. 5) Density pattern in a given habitat determines its quality for the individual. 6) Settling selection among habitats and the number of safe sites controls the distribution of densities among habitats.     

Mycotoxins in Mexico: Epidemiology, management, and control strategies

Mycotoxin-producing molds species are extremely common. Many of them provoke serious diseases in humans and animals. These toxins occur, with varying severity, in agricultural products. Since Mexico is a big crops producer, the importance of the presence of these toxins is high. Currently, the Mexican regulation establishes limits only for aflatoxins in cereals and cereal products. No limits are set for other mycotoxins. Epidemiological data although limited, has shown that an important number of samples contain mycotoxin limits above those established abroad. Several strategies for reducing contamination have been conducted in the country such as development of hybrid corn, control of insect population, use of natural products, and modification of nixtamalization and extraction procedures. Although significant research on this field has been conducted, there is still a great need for information to determine the incidence of mycotoxins in Mexican products.     

Demography and evolution of an urban ethnic community: Polish Hill, Pittsburgh.

Polish Hill is an urban, ethnic enclave of approximately 3000 residents residing in a 25-block area of Pittsburgh. This paper documents changes in the fertility, morbidity, and mortality patterns in the community from the turn of the century to the present. The demographic reconstruction is based upon baptismal and marriage records, the administration of demographic proformae and population censuses. The high mortality, morbidity, and fertility variance suggest that the immigrant population has experienced a period of high opportunity for selection in the early 1900's and that Crow's index was gradually reduced to its present level.     

Nuthatches (Sitta europaea: Aves) in forest fragments: demography of a patchy population

Breeding density, local survival and summer recruitment of nuthatches were evaluated in a population scattered over many small (1–30 ha) forest fragments, and compared with study plots inside larger forests. Since most young birds settle outside the fragment in which they were born this population corresponds to the “patchy population” concept implying that patterns in abundance may be better explained by processes at the population level than by metapopulation processes. Mean breeding density was c. 50% lower in fragments and decreased with regional isolation (distance from larger forests) but not with local isolation (distance to nearby fragments). Local survival of adults and established (i.e. territorial) 1st-year birds was not related to forest size or isolation. However, fewer young birds settled in summer in the fragments compared with a large forest. This difference probably reflects high mortality during the sensitive dispersal phase. Moreover, the observed number of recruits and their estimated survival was insufficient to maintain the breeding population, suggesting significant net immigration from larger forests. This “rescue effect” explains why densities are affected by regional, but not local isolation. Received: 14 December 1998 / Accepted: 1 March 1999     

Mating,births, and transitions: a flexible two-sex matrix model for evolutionary demography

Models of sexually-reproducing populations that consider only a single sex cannot capture the effects of sex-specific demographic differences and mate availability. We present a new framework for two-sex demographic models that implements and extends the birth-matrix mating-rule approach of Pollak. The model is a continuous-time matrix model that explicitly includes the processes of mating (which is nonlinear but homogeneous), offspring production, and demographic transitions and survival. The resulting nonlinear model converges to exponential growth with an equilibrium population composition. The model can incorporate age- or stage-structured life histories and flexible mating functions. As an example, we apply the model to analyze the effects of mating strategies (polygamy or monogamy, and mated unions composed of males and females, of variable duration) on the response to sex-biased harvesting. The combination of demographic complexity with the interaction of the sexes can have major population dynamic effects and can change the outcome of evolution on sex-related characters.     

Towards welfare biology: Evolutionary economics of animal consciousness and suffering

Welfare biology is the study of living things and their environment with respect to their welfare (defined as net happiness, or enjoyment minus suffering). Despite difficulties of ascertaining and measuring welfare and relevancy to normative issues, welfare biology is a positive science. Evolutionary economics and population dynamics are used to help answer basic questions in welfare biology: Which species are affective sentients capable of welfare? Do they enjoy positive or negative welfare? Can their welfare be dramatically increased? Under plausible axioms, all conscious species are plastic and all plastic species are conscious (and, with a stronger axiom, capable of welfare). More complex niches favour the evolution of more rational species. Evolutionary economics also supports the common-sense view that individual sentients failing to survive to mate suffer negative welfare. A kind of God-made (or evolution-created) fairness between species is also unexpectedly found. The contrast between growth maximization (as may be favoured by natural selection), average welfare, and total welfare maximization is discussed. It is shown that welfare could be increased without even sacrificing numbers (at equilibrium). Since the long-term reduction in animal suffering depends on scientific advances, strict restrictions on animal experimentation may be counter-productive to animal welfare.     

Variable demography in relation to germination time in the annual plant Tagetes micrantha Cav. (Asteraceae)

This study tests whether variability in a life history trait such as emergence time has ecological and evolutionary significance in seasonal environments due to their relationship with fitness components. The population dynamics of nine different cohorts of seedlings emergence were analyzed in a natural population of the annual herb Tagetes micrantha Cav. (Asteraceae). Temporal variation in seedling emergence was related to the pattern of precipitation, while spatial variation could be related to topographical heterogeneity. Plants that emerged at the beginning of the season (early germination) had lower probabilities of survivorship than those that emerged at the end of the season (late germination). In contrast, plants that emerged early had, on average, higher fecundity than those that emerged late. The net result of these contrasting patterns of survival and fecundity constitute a life history trade-off in T. micrantha.     

Rarity, commonness, and patterns of species richness: the mammals of Mexico

Aim To determine whether rare or common species contribute most to overall patterns of spatial variation in extant species richness. Location Mexico. Methods Using data on the distribution of mammal species across Mexico at a quarter degree resolution, we ranked species from the most widespread to the most restricted (common‐to‐rare) within the study area, and from the most restricted to the most widespread (rare‐to‐common), and generated a sequence of patterns of species richness for increasing numbers of species. At each stage along both series of richness patterns, we correlated the species richness pattern for the subassemblage with that of the full assemblage. This allows comparison of subassemblages of the n most common with the n most rare species, in terms of how well they match the full assemblage richness pattern. Further analyses examined the effects on these patterns of correlation of the amount of raw information contained in the distributions of given numbers of rare and common species. Results For the mammals of Mexico the more widely distributed species contribute disproportionately to patterns of species richness compared with more restricted species, particularly for non‐volant species and endemic species. This is not simply a consequence of differences in the volumes of information contained in the distributions of rare and common species, with the disproportionate contribution of common species if anything being sharpened when these differences are taken into account. The pattern is most clearly demonstrated by endemic species, suggesting that the contribution of common species is clearest when the causes of rarity and commonness are limited to those genuinely resulting in narrow and widespread geographical ranges, respectively, rather than artificial (e.g. geopolitical) boundaries to the extents of study regions. Conclusions Perhaps surprisingly, an understanding of the determinants of overall patterns of species richness may gain most from consideration of why common species occur in some areas and are absent from others, rather than consideration of the distributions of rare species.     

Power/Knowledge,Power/Ignorance: Forest Fires and the State in Mexico

For over a century the Mexican state has justified its control of forests by claiming that rural people are ignorant and destructive fire setters, in the face of abundant evidence to the contrary. Academic and popular stereotypes of the state have tended to assume that official power and knowledge go hand in hand. In an institutional ethnography ofthe Mexican environment agency, SEMARNAP, I. show how official ignorance is deployed both within and outside state forestry institutions, and how ignorance and complicity may be as important as knowledge in asserting state power. Rather than internalizing official fire discourse, rural people in Mexico learn to mouth polite fictions in their encounters with officials. I argue that the scholarship on governmentality derived from Foucault has uncritically internalized the link between power and knowledge. A closer attention to the production and translation of knowledge within state institutions leads to a more nuancedunderstanding of various forms of obscurity and ignorance which accompany official knowledge claims. This paper is drawn from my fieldwork and archival research in Mexico in the summer of 1998 and between April 2000 and August 2001.     

Phylogeography and demography of sympatric sister surfperch species, Embiotoca jacksoni and E. lateralis along the California coast: historical versus ecological factors

With 18 closely related endemic species that radiated in a diversity of ecological niches, the California surfperches (Embiotocidae) species flock is a good candidate for the study of sympatric speciation. Resource partitioning has been suggested as an important driving force in the radiation of the surfperch family. Within the family, two congeneric sister species, Embiotoca jacksoni and E. lateralis, are known to compete strongly for a preferred single food resource and may be used as a model of ecological interactions for the family. Along the California coast, the distribution of the two species differs. Embiotoca jacksoni has a continuous range, whereas E. lateralis shows a disjunction with a distribution gap in the Southern California Bight. Two hypotheses may explain this disjunct distribution. Ecological competition may have displaced E. lateralis in favor of E. jacksoni. Alternatively, a common vicariant event may have separated the species into northern and southern populations, followed by secondary contact in E. jacksoni but not in E. lateralis. The two hypotheses predict different phylogeographic and demographic signatures. Using a combined phylogeographic and coalescent approach based on mitochondrial control region data, we show that vicariance can only account for a portion of the observed divergences. Our results are compatible with a significant role played by ecological competition in the southern range of the species.