Aspidoscelis costatus costatus (Squamata, Teiidae): high elevation clutch production for a population of whiptail lizards

Artículo del tamaño de nidada en la lagartija Aspidoscelis costatus costatus.Clutch size and number of clutches per reproductive cycle are important life history traits that can be influenced by anatomical, physiological, evolutionary, and ecological factors. This report on the clutch size and number of clutches of an endemic Mexican whiptail lizard, Aspidoscelis costatus costatus (Cope, 1878), is based on a study of population at an unsually high elevation for a member of this genus. The study site is located in Ixtapan de la Sal, southeastern Estado de México, Central Mexico, at 2090 m a.s.l. Lizards were sampled in June 2006, and from May to July 2007, where females of Aspidoscelis costatus costatus were collected by hand along a drift fence. Female reproductive condition was evaluated based on abdominal palpation for presence of developing eggs; clutch size was determined by actual counts of either vitellogenic follicles or oviductal eggs. The smallest reproductive female was 77 mm snout vent length; females produced a minimum of two clutches during the breeding season, the mean clutch size of 6.5 eggs (n = 33) was one of the largest reported for the genus. However, both length and width of its eggs, and the relative clutch mass have not been diminished by development of a large clutch. Additionally, comparisons of clutch size were undertaken within the polytypic A. costatus complex, within the genus Aspidoscelis, and between certain genera of whiptail lizards. This apparently represents the first study of whiptail lizards (genus Aspidoscelis), assessing the aforementioned reproductive characteristics, in a population above 2000 m

Reproductive activity in males of Sceloporus variabilis: Little time to rest, long time to breed

Los reptiles presentan una gran variedad de patrones reproductores, que, en el caso de los machos, van desde diferencias en la duración del ciclo reproductor (Huang, 1997; Lozano et al., 2015), la época (primavera y/o verano, época de lluvias y/o sequía) en que se lleva a cabo (Vitt y Goldberg, 1983; Ramírez-Pinilla, 1991; Ferreira et al., 2002; Goldberg, 2008) o si la actividad es continua o estacional (Méndez-de la Cruz et al., 2015). La actividad reproductora continua, es aquélla donde la producción de espermatozoides es constante durante todo el año y aunque suele ser asociada a especies tropicales (Sherbrooke, 1975; Vial y Stewart, 1985; Van Sluys, 1993), se ha registrado en especies de clima templado (Hernández-Gallegos et al., 2002; Lozano et al., 2015). En contraste, la actividad reproductora estacional es aquélla donde los machos llevan a cabo la gametogénesis en periodos específicos del año, generalmente en primavera o verano/otoño, y está típicamente asociada a especies de clima templado (Abu-Zinadah, 2008; Goldberg, 2011; Rheubert et al., 2014). De igual modo, la actividad reproductora estacional también ha sido registrada en especies tropicales (Ochotorena et al., 2005; Granados-González et al., 2017).The reproductive activity of reptiles is typically assessed using monthly sampling. The spermatogenic cycle of Sceloporus variabilis was recently assessed using the aforementioned methodology, and only two spermatogenic phases (recrudescence and maximum activity) were observed. The authors hypothesized that quiescence and regression must occur in a short period (less than a month), which was not visualized by their monthly sampling methods. Thus, the entire spermatogenic cycle displayed by this species may have not been adequately represented. The present study assessed the spermatogenic cycle of S. variabilis in those months where the spermatogenic activity passes from maximum activity (July) to recrudescence (August) using weekly sampling to test the hypothesis that quiescence and regression do indeed occur. The results showed a regression period for 2 weeks, whereas quiescence was not observed. These results lead us to two hypotheses: (a) quiescence occurs in a very short period (days/hours) or (b) does not occur in this species. The data generated in this study suggest that species exhibiting rapid changes in spermatogenic activity need to be assessed at more frequent intervals to accurately depict the spermatogenic stages.CONACY

BIOLOGIA CELULAR

GUIA PEDAGOGIC

Aspidoscelis sackii gigas. Color pattern variation.

Archivo de la variación en la coloración de la lagartija Aspidoscelis sackii gigas.Se describe la variación en la coloración de la lagartija Aspidoscelis sackii gigas en dos poblaciones de los estados de México y Guerrero

Dimorfismo sexual de Aspidoscelis costata costata (Squamata: Teiidae) en el sur del Estado de México, México

El dimorfismo sexual es una característica extendida en lacertilios y se relaciona con la adecuación de los individuos. En este estudio se analizó si Aspidoscelis costata costata (Squamata) presenta dimorfismo sexual al sur del Estado de México, México, especialmente en relación a su forma corporal altamente conservada dentro de la familia Teiidae. La población estudiada habita a 1500 msnm. Se utilizaron individuos adultos que fueron capturados y liberados durante estudios ecológicos. Para cada individuo se registró la longitud hocico-cloaca, el peso corporal, largo de la cabeza, ancho de la cabeza, alto de la cabeza, longitud del fémur y distancia interaxilar. Los análisis realizados indicaron que los machos fueron más grandes en longitud hocico-cloaca y peso; además presentaron dimensiones más grandes en cabeza y fémur que hembras de la misma longitud hocico-cloaca. La distancia interaxilar fue mayor en hembras que en machos de la misma longitud hocico-cloaca. El dimorfismo sexual de A. costata costata puede explicarse por selección sexual y selección por fecundidad

Female reproductive cycle and clutch size of Aspidoscelis costata costata (Squamata: Teiidae) from Tonatico, Estado de México

Female reproductive cycle and clutch size are important life history traits in lizards that can be influenced by biotic and/or abiotic factors. Here, the ovarian cycle and clutch size of a high-elevation population (15001600 m) of Aspidoscelis costata costata in Central Mexico are described. Females were collected monthly between 2005 and 2007, and their reproductive condition was evaluated based on appearance and size of ovarian follicles and presence/absence of oviductal eggs. The reproductive cycle was markedly seasonal with asynchrony in reproductive condition among females. Vitellogenic and gravid females were recorded from April (end of the dry season) through July (middle of the rainy season). Although this population inhabits a semi-humid warm climate, the timing of female reproduction in A. costata costata is similar to the cycle of temperate-zone species of Aspidoscelis . Females produced a single clutch annually with an average clutch size of 7.7 ± 0.44 eggs (median 8 eggs, range 414), which is the largest reported to date within the genus Aspidoscelis

Current state-of-the-art and gaps in platform trials: 10 things you should know, insights from EU-PEARL

Summary: Platform trials bring the promise of making clinical research more efficient and more patient centric. While their use has become more widespread, including their prominent role during the COVID-19 pandemic response, broader adoption of platform trials has been limited by the lack of experience and tools to navigate the critical upfront planning required to launch such collaborative studies. The European Union-Patient-cEntric clinicAl tRial pLatform (EU-PEARL) initiative has produced new methodologies to expand the use of platform trials with an overarching infrastructure and services embedded into Integrated Research Platforms (IRPs), in collaboration with patient representatives and through consultation with U.S. Food and Drug Administration and European Medicines Agency stakeholders. In this narrative review, we discuss the outlook for platform trials in Europe, including challenges related to infrastructure, design, adaptations, data sharing and regulation. Documents derived from the EU-PEARL project, alongside a literature search including PubMed and relevant grey literature (e.g., guidance from regulatory agencies and health technology agencies) were used as sources for a multi-stage collaborative process through which the 10 more important points based on lessons drawn from the EU-PEARL project were developed and summarised as guidance for the setup of platform trials. We conclude that early involvement of critical stakeholder such as regulatory agencies or patients are critical steps in the implementation and later acceptance of platform trials. Addressing these gaps will be critical for attaining the full potential of platform trials for patients. Funding: Innovative Medicines Initiative 2 Joint Undertaking with support from the European Union’s Horizon 2020 research and innovation programme and EFPIA