Javier López-Upton

Reproductive indicators in natural populations of Douglas-fir in Mexico

The reproductive capacity in nine Mexican Douglas-fir populations was determined by analyzing seed production traits from 144 trees collected in 2001. Significant variation was found for all traits among populations; they contributed between 21% and 43% of total phenotypic variation found in these traits, indicating broad differences in reproductive capacity for that particular year. Seed efficiency (filled seed/seed potential) varied from 14% to 42% among populations; all populations from Central Mexico had a seed efficiency below 25%. The proportion of developed that were empty seeds varied from 0.40 to 0.81 among populations, whereas seed size varied also from 0.88 to 1.21 g per 100 seeds among them. Average ratio of filled seed weight to cone weight (reproductive efficiency) was 29.6 mg g−1, but it varied three-fold between populations with extreme values. Populations with larger cones had greater seed potential and heavier seed but not necessarily higher reproductive or seed efficiency. Most reproductive indicators were significantly correlated with latitude, with lower values in the marginal populations from Central Mexico, in the southern extreme of the species range. Given these results, the need for conservation of Douglas-fir populations in Central Mexico is discussed.

Range-wide chloroplast and mitochondrial DNA imprints reveal multiple lineages and complex biogeographic history for Douglas-fir

The contemporary genetic structure of species offers key imprints of how organisms responded to past geological and climatic events, which have played a crucial role in shaping the current geographical distribution of north-temperate organisms. In this study, range-wide patterns of genetic variation were examined in Douglas-fir (Pseudotsuga menziesii), a dominant forest tree species distributed from Mexico to British Columbia in western North America. Two organelle DNA markers with contrasting modes of inheritance were genotyped for 613 individuals from 44 populations. Two mitotypes and 42 chlorotypes were recovered in this survey. Both genomes showed significant population subdivision, indicative of limited gene flow through seeds and pollen. Three distinct cpDNA lineages corresponding to the Pacific Coast, the Rocky Mountains, and Mexico were observed. The split time of the two lineages from the Rockies lineage was dated back to 8.5xa0million years (Ma). The most recent common ancestors of Mexican and coastal populations were estimated at 3.2 and 4.8xa0Ma, respectively. The northern populations of once glaciated regions were characterized by a high level of genetic diversity, indicating a large zone of contact between ancestral lineages. A possible northern refugium was also inferred. The Mexican lineage, which appeared established by southward migration from the Rockies lineage, was characterized by the lowest genetic diversity but highest population differentiation. These results suggest that the effects of Quaternary climatic oscillations on the population dynamics and genetic diversity of Douglas-fir varied substantially across the latitudinal section. The results emphasize the pressing need for the conservation of Mexican Douglas-fir.

Effect of cutting age and substrate temperature on rooting of Taxus globosa

Taxus globosa (Mexican yew) is a conifer endemic to México and Central America. It produces a substance known as taxol, which is useful in treatment of ovarian cancer. Because seed production for this dioecious tree is limited, and seed germination is extremely difficult, the use of cuttings could facilitate propagation of this species. With the intention of massively propagating individuals selected for taxol content, two trials were established in which the effect of substrate temperature (average temperatures 18 and 23°C), age (i.e., young vs. old shoots) and management of cuttings, as well as clone variation in rooting capacity, were evaluated. Low temperature favored rooting (53 vs. 34% on average for the two trials); younger shoots rooted three times (61 vs. 23%) more than mature ones, while basal wounding did not affect rooting capacity. A wide variation was found in rooting capacity of clones (8–76%), which could be associated with genetic or physiological differences among donor trees.

Ruminal degradation of aerial biomass and seeds of wild species of Lupinus

M. Pablo-Perez, L.C. Lagunes-Espinoza, J. Ramos-Juarez, J. Lopez-Upton, E.M. ArandaIbanez, and L. Vargas-Villamil. 2014. Ruminal degradation of aerial biomass and seeds of wild species of Lupinus. Cienc. Inv. Agr. 41(1): 5-12. Ruminal degradation of dry matter (DMD) and crude protein (CPD) for aerial biomass at the flowering stage and for the seeds of L. campestris, L. exaltatus, L. hintonii and L. montanus was determined using the nylon bag technique with two fistulated steers in five incubation times (3, 9, 12, 24 and 48 h), including a sample of soybean paste (SP). The data obtained were analyzed using PROC MIXED of SAS for repeated measures. The results showed interactions between species and incubation time for DMD and CPD. Among species of lupine, a high DMD and CPD of seeds were observed after three hours of incubation. At 48 h, DMD and CPD did not show significant variation between species: DMD ranged from 94.3% to 96.7% and CPD from 98.9 to 99.2%. The degradation rate of the insoluble fraction of the DM (kd) in lupine seeds ranged from 6.3 to 8.1% h -1 , while that of the soluble fraction (SF) ranged from 42.3 to 57.3%, lower value that observed in SP. The DMD and CPD of aerial biomass showed statistically significant differences between species at 48 h of incubation. L. hintonii showed the lowest DMD (69.6%) and CPD (88.9%). L. montanus and L. campestris showed a lower SF and kd (kd of 5.4% h -1 in both, and 35.4 and 37.2 for SF, respectively) and high CPD of aerial biomass. It is concluded that the DM and CP of seeds and biomass of wild lupine were highly degradable as of 3 h of incubation. At 48 h, there were statistically significant differences between DMD and CPD of aboveground biomass (AGB). L. campestris and L. exaltatus showed the highest DMD and CPD of AGB and similar DMD and CPD of seeds.

Climate-based seed zones for Mexico: guiding reforestation under observed and projected climate change

Seed zones for forest tree species are a widely used tool in reforestation programs to ensure that seedlings are well adapted to their planting environments. Here, we propose a climate-based seed zone system for Mexico to address observed and projected climate change. The proposed seed zone classification is based on bands of climate variables often related to genetic adaptation of tree species: mean coldest month temperature (MCMT) and an aridity index (AHM). The overlay of the MCMT and AHM for the 1961–1990 period resulted in 63 climate-based zones. Climate change observed over the last three decades has resulted in an increase of +xa00.74xa0°C for MCMT and a shift toward overall drier conditions across Mexico. By the 2050s, MCMT is expected to increase by +xa01.7xa0°C and AHM shifts further towards drier conditions. We recommend moving seed sources from warm, dry locations towards currently wetter and cooler planting sites, to compensate for climate change that has already occurred and is expected to continue for the next decades. We contribute a straight-forward climate-based seed zone system that allows practitioners to match seed procurement regions with planting regions under observed and anticipated climate change. Our transfer recommendations using climate-based zones can be implemented within the existing seed zone system, which often span large climate gradients.

Economic valuation of the forest biodiversity in Mexico, a review

El deterioro creciente de los recursos naturales crea la necesidad de valorar los servicios ambientales, incluidos los de la biodiversidad. La valoracion economica de esta se ha focalizado en bienes y servicios sin mercado, lo cual es complicado. Se han desarrollado tecnicas para medir estos valores cuya aceptacion se ha incrementado ultimamente. En este trabajo se hizo una busqueda de las valoraciones economicas efectuadas en Mexico. Casi la totalidad de estudios de valoracion realizados en el pais se restringen a los metodos de valoracion contingente (MVC) y costo de viaje (MCV). El unico nivel de biodiversidad explorado es el de ecosistema. No se conocen trabajos desarrollados en terminos de los bienes y servicios sin mercado a nivel de gen y especie. El metodo de valoracion contingente es el mas utilizado (11 estudios), le sigue el metodo costo de viaje con un estudio realizado conjuntamente con el MVC. Ocho estudios no consideraron los sesgos mas importantes (tiempo, sustitucion, multiples destinos, vehiculo de pago, estrategico e hipotetico) de estos metodos.