Distribución de la variación genética de insectos asociados a Hesperoyucca whipplei en la península de Baja California

Distribution of genetic variation of insects associated with Hesperoyucca whipplei in the Baja California peninsula

Roberto Suárez Hernández (2024, [Tesis de maestría])

El tipo de interacción ecológica obligada entre plantas hospederas y sus insectos asociados ha demostrado tener un impacto en la diversidad genética de las especies involucradas. La yuca de chaparral, Hesperoyucca whipplei, presenta una relación de mutualismo obligado con la polilla polinizadora Tegeticula maculata, y de comensalismo obligado con la polilla Prodoxus marginatus. Ambos insectos depositan sus huevos en estructuras de la flor y se alimentan del fruto en desarrollo. Con el fin de determinar el efecto de la interacción ecológica sobre la diversidad genética de los insectos, en este estudio se evaluó el nivel de variación y estructura genética de ambas polillas a lo largo de la península de Baja California. Se amplificó el gen mitocondrial COI en 86 individuos de T. maculata y 120 individuos de P. marginatus. La diversidad haplotípica fue menor en T. maculata (Hd = 0.601) en comparación con P. marginatus (Hd = 0.966) mientras que la diversidad nucleotídica fue baja en ambas especies (Pi= 0.0018 y 0.007 respectivamente). Las redes haplotípicas, el AMOVA, la prueba mismatch y los valores D de Tajima en T. maculata indican un patrón de expansión poblacional, mientras que en P. marginatus indican una estabilidad demográfica. Estos hallazgos sustentan que el mutualismo obligado entre H. whipplei y T. maculata, en contraste con el comensalimo obligado con P. marginatus, tiene un impacto directo en el nivel de la diversidad genética de las polillas, más que en su estructura a lo largo del área de distribución.

The type of obligate ecological interaction between host plants and their associated insects has been showing to have an impact on the genetic diversity of the species involved. The chaparral yuca (Hesperoyucca whipplei) presents a relationship of obligate mutualism with the pollinating moth Tegeticula maculata, and obligate commensalism with the moth Prodoxus marginatus. Both insects deposit their eggs in flower structures and feed on the developing fruit. To determine the effect of ecological interactions on insects’ genetic diversity, this study evaluated the level of variation and genetic structure of both moths throughout the Baja California peninsula. The mitochondrial COI gene was amplified in 86 individuals of T. maculata and 120 individuals of P. marginatus. Haplotypic diversity was lower in T. maculata (Hd = 0.601) compared to P. marginatus (Hd = 0.966) while nucleotide diversity was low in both species (pi = .0018 and 0.007 respectively). Haplotype networks, AMOVA, mismatch test and Tajima’s D values in T. maculata indicate a pattern of population expansion, whereas in P. marginatus they indicate demographic stability. These findings support that obligate mutualism between H. whipplei and T. maculata, in contrast, to obligate commensalism with P. marginatus, has a direct impact on the level of genetic diversity of the moths, rather than on their structure across the distribution.

mutualismo, comensalismo, filogeografía comparativa, polillas mutualism, commensalism, comparative phylogeography, moth BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA DE INSECTOS (ENTOMOLOGÍA) ECOLOGÍA DE LOS INSECTOS ECOLOGÍA DE LOS INSECTOS

Variación morfológica de las hormigas Myrmecocystus de las dunas costeras de Baja California, México

Morphological variation of Myrmecocystus ants from the coastal dunes of Baja California, Mexico

Samuel Antonio Hernández Jiménez (2023, [Tesis de maestría])

La península de Baja California cuenta con dunas costeras aisladas sobre las cuales se distribuyen hormigas del género Myrmecocystus Snelling, 1976, cuya distribución se restringe en estos hábitats; la artropofauna de estas dunas es poco conocida. Se evaluaron las diferencias morfológicas de Myrmecocystus de seis poblaciones recolectadas a lo largo de la península de Baja California correspondientes a seis dunas. Para medir las diferencias morfológicas de las poblaciones, se analizaron 109 individuos, 20 por cada duna, a excepción de una duna en donde sólo se recolectaron nueve individuos. Para evaluar los cambios de forma intra e interpoblacionales, se analizaron dos estructuras morfológico-funcionales: 1) cabeza, incluyendo el clípeo relacionada con la competencia y alimentación y 2) tórax, incluyendo el propodeo, que muestra la diferencia de casta entre obreras. Con una cámara fija montada en un microscopio estereoscópico se tomaron 198 microfotografías digitales, para evaluar cambios de forma mediante un análisis de morfometría geométrica. Se detectaron diferencias asociadas al aislamiento geográfico. La variación observada en la cabeza puede ayudar a diferenciar las poblaciones del norte de la península (Santa Rosaliíta, Punta Mazo, Guerrero Negro y Punta Abreojos) y las del sur (Las Barrancas y Bahía Magdalena), la variación morfológica del tórax no mostró diferencias significativas. Existen variaciones intraespecíficas que podrían ser consecuencia de las condiciones ambientales (fenotípicas) o por procesos aleatorios como la deriva génica. El presente estudio arroja datos de la variación morfológica de seis poblaciones que representan dos especies de Myrmecocystus aun no descritas para la península de Baja California. Estos resultados repercutirán en la descripción y un aumento documentado de la biodiversidad de la artropofauna bajacaliforniana.

The Baja California peninsula has isolated coastal dunes on which ants of the genus Myrmecocystus Snelling, 1976 are distributed, whose distribution is restricted in these habitats; The arthropofauna of these dunes is poorly understood. The morphological differences of Myrmecocystus were evaluated from six populations collected along the Baja California peninsula corresponding to six dunes. To measure the morphological differences of the populations, 109 individuals were analyzed, 20 for each dune, except for one dune where only nine individuals were collected. To evaluate intra- and interpopulation shape changes, two morphological-functional structures were analyzed: 1) head, including the clypeus related to competition and feeding, and 2) thorax, including the propodeum, which shows the caste difference between workers. With a fixed camera mounted on a stereoscopic microscope, 198 digital microphotographs were taken to evaluate shape changes through a geometric morphometry analysis. Differences associated with geographic isolation were detected. The variation observed in the head can help to differentiate the populations of the north of the peninsula (Santa Rosaliíta, Punta Mazo, Guerrero Negro, and Punta Abreojos) and those of the south (Las Barrancas and Magdalena Bay), the morphological variation of the thorax did not show significant differences. There are intraspecific variations that could be a consequence of environmental conditions (phenotypic) or random processes such as gene drift. The present study yields data on the morphological variation of six populations representing two species of Myrmecocystus not yet described for the Baja California peninsula. These results will have an impact on the description and a documented increase in the biodiversity of the Baja Californian arthropofauna.

Alometría, Especiación, Morfometría Geométrica, Forma, Especies no descritas Allotometry, Speciation, Geometric Morphometry, Shape, Undescribed Species BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA DE INSECTOS (ENTOMOLOGÍA) MORFOLOGÍA DE LOS INSECTOS MORFOLOGÍA DE LOS INSECTOS

Biodiversity conservation in an anthropized landscape: Trees, not patch size drive, bird community composition in a low-input agroecosystem

ERIC MELLINK BIJTEL (2017, [Artículo])

One of the most typical agro-ecosystems in the Llanos de Ojuelos, a semi-arid region of central Mexico, is that of fruit-production orchards of nopales (prickly pear cacti). This perennial habitat with complex vertical structure provides refuge and food for at least 112 species of birds throughout the year. Nopal orchards vary in their internal structure, size and shrub/ tree composition, yet these factors have unknown effects on the animals that use them. To further understand the conservation potential of this agro-ecosystem, we evaluated the effects of patch-size and the presence of trees on bird community composition, as well as several habitat variables, through an information-theoretical modelling approach. Community composition was obtained through a year of census transects in 12 orchards. The presence of trees in the orchards was the major driver of bird communities followed by seasonality; bird communities are independent of patch size, except for small orchard patches that benefit black-chin sparrows, which are considered a sensitive species. At least 55 species of six trophic guilds (insectivores, granivores, carnivores, nectivores, omnivores, and frugivores) used the orchards. Orchards provide adequate habitat and food resources for several sensitive species of resident and migratory sparrows. The attributes that make orchards important for birds: trees, shrubs, herb seeds, and open patches can be managed to maintain native biodiversity in highly anthropized regions with an urgent need to find convergence between production and biological conservation. © 2017 Mellink et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

agroecosystem, carnivore, chin, conservation biology, driver, frugivore, granivore, habitat, human, insectivore, landscape, nonhuman, omnivore, orchard, resident, seasonal variation, shrub, sparrow, theoretical model, agriculture, animal, biodiversit CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA