Cecilia Jiménez-Sierra

Some limnological features of three lakes from Mexican neotropics

A limnological survey was conducted in three water bodies from the tropical rain forest region of southeast Veracruz, Mexico, in order to recognize their morphometric characteristics and to define their mixing patterns. These were: a temporary pond, Laguna del Zacatal (A=7.64 ha, Zm =13.0 m); and two permanent lakes, Laguna Escondida (A =18.26 ha, Zm = 32.5 m) and Lago de Catemaco (A = 7254 ha, Zm = 22.0 m). Both El Zacatal and La Escondida are warm monomictic, whereas Lago de Catemaco is polymictic. Our results support the hypothesis that most tropical lakes are prone to winter overturn. Dissolved oxygen showed large variation, from almost constant epilimnetic saturation in all three lakes to hypolimetic anoxia in Laguna Escondida. Differences in mixing between lakes are determined by the joint influence of morphometry, rainfall and wind.

Alternative glacial-interglacial refugia demographic hypotheses tested on Cephalocereus columna-trajani (Cactaceae) in the intertropical Mexican drylands

Historic demography changes of plant species adapted to New World arid environments could be consistent with either the Glacial Refugium Hypothesis (GRH), which posits that populations contracted to refuges during the cold-dry glacial and expanded in warm-humid interglacial periods, or with the Interglacial Refugium Hypothesis (IRH), which suggests that populations contracted during interglacials and expanded in glacial times. These contrasting hypotheses are developed in the present study for the giant columnar cactus Cephalocereus columna-trajani in the intertropical Mexican drylands where the effects of Late Quaternary climatic changes on phylogeography of cacti remain largely unknown. In order to determine if the historic demography and phylogeographic structure of the species are consistent with either hypothesis, sequences of the chloroplast regions psbA-trnH and trnT-trnL from 110 individuals from 10 populations comprising the full distribution range of this species were analysed. Standard estimators of genetic diversity and structure were calculated. The historic demography was analysed using a Bayesian approach and the palaeodistribution was derived from ecological niche modelling to determine if, in the arid environments of south-central Mexico, glacial-interglacial cycles drove the genetic divergence and diversification of this species. Results reveal low but statistically significant population differentiation (FST = 0.124, P < 0.001), although very clear geographic clusters are not formed. Genetic diversity, haplotype network and Approximate Bayesian Computation (ABC) demographic analyses suggest a population expansion estimated to have taken place in the Last Interglacial (123.04 kya, 95% CI 115.3–130.03). The species palaeodistribution is consistent with the ABC analyses and indicates that the potential area of palaedistribution and climatic suitability were larger during the Last Interglacial and Holocene than in the Last Glacial Maximum. Overall, these results suggest that C. columna-trajani experienced an expansion following the warm conditions of interglacials, in accordance with the GRH.

High tolerance to high-light conditions for the protected species Ariocarpus kotschoubeyanus (Cactaceae)

In this study, we found a high tolerance to high-light conditions for the protected cactus Ariocarpus kotschoubeyanus, which could explain why this species does not show preferences to protected sites under nurse plants.

Forgotten Social Issues for Achieving Long-Term Conservation in Protected Areas

Protected areas (PAs) are probably the most important conservation instrument in Mexico. Historically, their planning and implementation have focused on ecological data ignoring values, attitudes, behaviors, and institutions of the people living in the PA, thus inhibiting its long-term effectiveness. Here, we review three social disciplines that might enhance the understanding of the social sphere around PAs: conservation psychology (CP), social-ecological system framework (SESF), and conservation marketing (CM). CP is crucial to understand human behavior toward nature or conservation. We present different tools for evaluating values, attitudes, and behaviors that are relevant for understanding conservation outcomes. SESF allows to systematically map and diagnose the pattern of interactions of relevant variables in search of factors that can be promoted or restricted to enable the involvement of local people in the planning and implementation of conservation programs and instruments. Finally, CM allows us to modulate and design conservation programs with specific end-state behaviors and target audiences to improve the success of the conservation actions. We proposed that using these disciplines in the design, implementation, and evaluation of the conservation programs, we will enable effective long-term conservation inside Mexican PAs.

Are Current Actions for Conservation in Mexico Enough? A Review of the Proximate and Ultimate Threats

Mexico is a mega-diverse country with a high percentage of endemic and threatened species. Biodiversity conservation and the maintenance of ecosystems functions must be a national priority. In this chapter, we present some examples at Mexico environmental transformation or resource use strategies, which had constituted direct or indirect threats to species and ecosystems conservation. We highlight the importance of considering the socio-ecological system approach to prevent species’ loss, environmental deterioration and to ensure the well-being of human societies.