Reproductive Biology and Life Cycle of Leydigia Louisi Mexicana (Anomopoda, Chydoridae), a Rare Species from Freshwater Littoral Environments

Abstract

The family Chydoridae comprises a group of organisms that is relevant in an ecological sense, representing more than 40% of the total number of species of Cladocera recorded in Mexico until now. Leydigia louisi mexicana is a chydorid recently described in the "Los Baños" water reservoir (disappeared by now), located on the Central Mexican High Plateau. Scarce information exists on the maintenance and culture of Chydoridae in the laboratory in general, and on the reproductive biology of this species in particular. Therefore, the present work aimed at establishing the adequate conditions for the growth and reproduction of the species in the laboratory as a conservation strategy, considering that the type locality does no longer exist and the current distribution of this species is most restricted in Mexico. To this end, we experimentally studied the life cycle of L. louisi mexicana by developing a culture procedure in which we assessed three factors: food (Pseudokirchneriella subcapitata and Saccharomyces cerevisiae), type of substrate (commercial soil and artificial sediment), and temperature (20 and 25 • C). Experiments were performed through individual assessment of reproductive responses, and by life table analysis. The highest longevity (52.70 ± 2.16 d) was observed in organisms fed S. cerevisiae, on artificial sediment, at 20 • C. The highest fecundity (22.3 ± 0.86 neonates), the largest number of clutches (14 ± 0.52), and the highest intrinsic rate of population growth (r = 0.19 ± 0.007 d −1 ) were recorded in organisms fed with S. cerevisiae, on artificial sediment, at 25 • C. The shortest generation time (T = 18.15 ± 0.59 d) was recorded when L. louisi mexicana was fed P. subcapitata, on artificial sediment, at 25 • C. The best reproductive responses were obtained when L. louisi mexicana was fed S. cerevisiae, on artificial sediment. The procedure developed provides fundamental biological information, and could be an option for the maintenance and propagation of other chydorids. RESUMENLa familia Chydoridae constituye un grupo relevante de organismos, desde el punto de vista ecológico, y representa más del 40% del número total de especies de Cladóceros registrados en 1 ) México hasta ahora. Leydigia louisi mexicana es un chidórido recientemente descrito del embalse "Los Baños" (ahora desaparecido), localizado en el Altiplano Mexicano. Existe escasa información sobre el mantenimiento y cultivo de chidóridos en el laboratorio en general, y sobre la biología reproductiva de esta especie en particular. Por lo tanto, el presente estudio tuvo como objetivo establecer las condiciones adecuadas para el crecimiento y reproducción en el laboratorio de esta especie, como una estrategia de conservación, puesto que la localidad tipo ya no existe y su distribución actual en México es muy restringida. Con este propósito se estudió experimentalmente el ciclo de vida de L. louisi mexicana mediante el desarrollo de un método de cultivo en el que se evaluaron tres factores: alimento (Pseudokirchneriella subcapitata y Sacchar...

Effect of diet and temperature on the culture of Alona guttata(Sars, 1862) (Cladocera: Chydoridae) under laboratory conditions

“…For chydorids, the intrinsic rate of population increase (r) is generally accepted to take low values, which are in most cases below or near 0.2/d (Martínez-Jerónimo & Gómez-Díaz, 2011;Nandini et al, 2007), with the exception of some species of the genus Eurycercus, which can reach high values for chydorids of up to 0.310/d (Table 2). Furthermore, the intrinsic rates of population increase are affected by temperature, for instance, Hann (1985) found that increasing temperatures promoted higher reproductive rates in chydorids by decreasing egg maturation times; therefore, in four species the highest "r" values were recorded at 24 -25ºC.…”