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Mexico City, Mexico

Ruiz Guajardo J.C.,University of Edinburgh | Schnabel A.,Indiana University at South Bend | Ennos R.,University of Edinburgh | Otero-Arnaiz A.,Instituto Nacional Of Ecologia | Stone G.,University of Edinburgh
Molecular Ecology | Year: 2010

Acacias across Africa have enormous ecological and economic importance, yet their population genetics are poorly studied. We used seven microsatellite loci to investigate spatial genetic structure and to identify potential ecological and geographic barriers to dispersal in the widespread acacia, Senegalia (Acacia) mellifera. We quantified variation among 791 individuals from 28 sampling locations, examining patterns at two spatial scales: (i) across Kenya including the Rift Valley, and (ii) for a local subset of 11 neighbouring locations on Mpala Ranch in the Laikipia plateau. Our analyses recognize that siblings can often be included in samples used to measure population genetic structure, violating fundamental assumptions made by these analyses. To address this potential problem, we maximized genetic independence of samples by creating a sibship-controlled data set that included only one member of each sibship and compared the results obtained with the full data set. Patterns of genetic structure and barriers to gene flow were essentially similar when the two data sets were analysed. Five well-defined geographic regions were identified across Kenya within which gene flow was localized, with the two strongest barriers to dispersal splitting the Laikipia Plateau of central Kenya from the Western and Eastern Rift Valley. At a smaller scale, in the absence of geographic features, regional habitat gradients appear to restrict gene flow significantly. We discuss the implications of our results for the management of this highly exploited species. © 2010 Blackwell Publishing Ltd. Source

Gerrodette T.,Southwest Fisheries Science Center | Rojas-Bracho L.,Instituto Nacional Of Ecologia
Marine Mammal Science | Year: 2011

Bycatch in artisanal gill nets threatens the vaquita, Phocoena sinus, with extinction. In 2008 the Mexican government announced a conservation action plan for this porpoise, with three options for a protected area closed to gill net fishing. The probability of success of each of the three options was estimated with a Bayesian population model, where success was defined as an increase in vaquita abundance after 10 yr. The model was fitted to data on abundance, bycatch, and fishing effort, although data were sparse and imprecise. Under the first protected area option, the existing Refuge Area for the Protection of the Vaquita, bycatch was about 7% of population size, and probability of success was 0.08. Under the second option with a larger protected area, the probability of success was 0.35. The third option was large enough to eliminate vaquita bycatch and had a probability of success >0.99. Probability of success was reduced if elimination of vaquita bycatch was delayed or incomplete. Despite considerable efforts by the Mexican government to support vaquita conservation, abundance will probably continue to decline unless additional measures to reduce vaquita bycatch are taken, such as banning gill nets within the vaquita's range and developing effective alternative fishing gear. 2011 by the Society for Marine Mammalogy Published 2011. This article is a US Government work and is in the public domain in the USA. Source

Avila-Forcada S.,National Autonomous University of Mexico | Avila-Forcada S.,Princeton University | Martinez-Cruz A.L.,University of Maryland University College | Munoz-Pina C.,Instituto Nacional Of Ecologia
Marine Policy | Year: 2012

Vaquita marina, a small species of porpoise endemic to the Northern Gulf of California in Mexico, is the world's most endangered cetacean species. With the purpose of preserving vaquita, the Mexican government launched PACE-Vaquita in 2008. This voluntary program offers an innovative schedule of compensations: as in a payment-for-conservation program, PACE-Vaquita compensates for temporary reductions in fishing effort; as in a program to accelerate technology adoption, PACE-Vaquita compensates for switching to vaquita-safe fishing methods; and as in a buyback program, PACE-Vaquita compensates fishermen for a permanent exit from fisheries. This paper seeks the factors explaining fishermen's participation in PACE-Vaquita during its first year of operation. Analysis is carried out through a multinomial logit specification on a data set collected one week after the enrollment deadline. This paper shows that fishermen with skills in alternative economic activities more likely quit fishing, and fishermen with relatively less productive vessels more likely switched to vaquita-safe fishing methods. Discussion of public policy implications is provided. © 2011 Elsevier Ltd. Source

Zamorano P.,Instituto Nacional Of Ecologia | Hendrickx M.E.,National Autonomous University of Mexico
Marine Biodiversity Records | Year: 2012

From samples taken during the oceanographic cruises TALUD IV-X in the southern and central Gulf of California, Mexico, 291 specimens of Lucinoma heroica were obtained in a depth interval of 731 to 991 m. The species occurred under conditions of severe (<0.1 ml l-1O2) and moderate hypoxia (0.1-0.5 ml l-1O2). The correlation between height and length of the shell showed isometric growth with a trimodal size distribution, showing an average interval of 3.75 mm to 47.40 mm in height and 4.96 mm to 54.00 mm in length. Small individuals (≤20 mm) were distributed in a moderate hypoxic environment, while the larger (>35 mm) tolerated an almost anoxic habitat. Medium-sized specimens (21-35 mm) were found in concentration close to 0.2 ml l-1O2. Average density was 1.532 ind l-1 in infauna samples (dredge and core) and 0.002 ind m-2 in epifauna samples (benthic sledge). © 2012 Marine Biological Association of the United Kingdom. Source

Wagner H.H.,Instituto Nacional Of Ecologia
Heredity | Year: 2016

Strong spatial genetic structure in plant populations can increase homozygosity, reducing genetic diversity and adaptive potential. The strength of spatial genetic structure largely depends on rates of seed dispersal and pollen flow. Seeds without dispersal adaptations are likely to be dispersed over short distances within the vicinity of the mother plant, resulting in spatial clustering of related genotypes (fine-scale spatial genetic structure, hereafter spatial genetic structure (SGS)). However, primary seed dispersal by zoochory can promote effective dispersal, increasing the mixing of seeds and influencing SGS within plant populations. In this study, we investigated the effects of seed dispersal by rotational sheep grazing on the strength of SGS and genetic diversity using 11 nuclear microsatellites for 49 populations of the calcareous grassland forb Dianthus carthusianorum. Populations connected by rotational sheep grazing showed significantly weaker SGS and higher genetic diversity than populations in ungrazed grasslands. Independent of grazing treatment, small populations showed significantly stronger SGS and lower genetic diversity than larger populations, likely due to genetic drift. A lack of significant differences in the strength of SGS and genetic diversity between populations that were recently colonized and pre-existing populations suggested that populations colonized after the reintroduction of rotational sheep grazing were likely founded by colonists from diverse source populations. We conclude that dispersal by rotational sheep grazing has the potential to considerably reduce SGS within D. carthusianorum populations. Our study highlights the effectiveness of landscape management by rotational sheep grazing to importantly reduce genetic structure at local scales within restored plant populations.Heredity advance online publication, 6 July 2016; doi:10.1038/hdy.2016.45. © 2016 The Genetics Society Source

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