The Numbers of Animals Used in Mexico for Scientific and Educational Purposes.

In Mexico, there are no official public and reliably reported data on the total number and species of non-human animals used for scientific purposes. The aim of the current study was to calculate the total numbers of animals used for scientific and educational purposes in Mexico, from January 2015 to October 2021, based on data requested from the National Institute of Transparency, Access to Information and Protection of Personal Data (INAI, in Spanish). In this period, authorised laboratory animal facilities reported the use of 5,437,263 animals for scientific and educational purposes. However, these data should be viewed with caution, since there is no official register of all Mexican institutions that use animals for these purposes. The use of various species of different taxonomic groups was reported, including mammals, birds, reptiles, amphibians, fish and invertebrates. The main scientific purposes of this animal use were: technological development; innovation; laboratory testing; production of biologicals; quality control; diagnostic purposes; basic and applied research; and education. A robust system for the licensing and approval of animal use, as well as a means to ensure compliance with the relevant regulations, are both urgently required. In addition, in order to regulate animal use, monitor animal care and protect their welfare, the creation of a publicly accessible national database that records the number and species of the animals used is imperative.

Response to Comment on "Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity".

Lambert et al question our retrospective and holistic epidemiological assessment of the role of chytridiomycosis in amphibian declines. Their alternative assessment is narrow and provides an incomplete evaluation of evidence. Adopting this approach limits understanding of infectious disease impacts and hampers conservation efforts. We reaffirm that our study provides unambiguous evidence that chytridiomycosis has affected at least 501 amphibian species.

Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity.

Anthropogenic trade and development have broken down dispersal barriers, facilitating the spread of diseases that threaten Earth's biodiversity. We present a global, quantitative assessment of the amphibian chytridiomycosis panzootic, one of the most impactful examples of disease spread, and demonstrate its role in the decline of at least 501 amphibian species over the past half-century, including 90 presumed extinctions. The effects of chytridiomycosis have been greatest in large-bodied, range-restricted anurans in wet climates in the Americas and Australia. Declines peaked in the 1980s, and only 12% of declined species show signs of recovery, whereas 39% are experiencing ongoing decline. There is risk of further chytridiomycosis outbreaks in new areas. The chytridiomycosis panzootic represents the greatest recorded loss of biodiversity attributable to a disease.

Superfetation in live-bearing fishes is not always the result of a morphological constraint.

Superfetation is an unusual reproductive strategy that consists of the presence of multiple broods at different developmental stages within a single female. One hypothesis that was proposed to explain its adaptive significance suggests that, in fishes, superfetation is a response to selective pressures that promote a thin and streamlined body shape, such as high-velocity water systems. Superfetation may allow for reduction in ovary size and hence improve streamlining because superfetating females carry few large, full-term embryos at any given time. We tested this morphological constraint hypothesis using reproductive and morphological data from several populations of two viviparous fishes of the family Poeciliidae (Poeciliopsis gracilis and Poeciliopsis infans). We found no evidence to support the morphological constraint hypothesis. In both species the degree of superfetation varied as a function of a complex interaction between source population and female size, and this interpopulation variation was not associated with the velocity of the water current. Contrary to what we expected, females of P. gracilis with more streamlined bodies were observed in rivers where water velocity is slow or moderate. In P. infans the velocity of the water current did not predict variation in body shape. Our results are noteworthy because a previous study which focused on a congeneric species (Poeciliopsis turrubarensis) demonstrated strong support for this hypothesis. However, based on our evidence we conclude that the association among increased superfetation, streamlined morphologies, and fast-flowing environments is not a general rule and that the adaptive value of superfetation may differ among species.

Spatial and temporal variation in superfoetation and related life history traits of two viviparous fishes: Poeciliopsis gracilis and P. infans.

Superfoetation is the ability of females to simultaneously bear multiple broods of embryos at different developmental stages. Most studies on the phylogenetic distribution of superfoetation and on the factors that potentially promote superfoetation ignore variation within species. Here, we studied 11 populations of two species of viviparous fishes of the family Poeciliidae (Poeciliopsis gracilis and Poeciliopsis infans) and document wide variation in superfoetation and in three related life history traits: brood size, individual embryo mass and total reproductive allotment. We found significant differences in the average number of simultaneous broods among populations of P. gracilis but not among populations of P. infans. In addition, we found even greater variation between months within populations for both species, although no specific pattern of temporal variation was evident. Instead of the expected consistency of seasonal differences in superfoetation across populations, we found that large variation among months within seasons and the amount and direction of this monthly variation differed widely between populations. Our results emphasize the importance of including intraspecific variation in superfoetation and other life history traits in studies that aimed at finding general explanations of life history trait evolution.

Chytridiomycosis survey in wild and captive mexican amphibians.

Mexico, a rich country in terms of amphibian diversity, hosts about 375 described species. Population declines have been documented for several species where it is evident that their habitat is being destroyed or modified. However, other species which inhabit pristine areas are declining as well. It has been suggested that the chytrid fungus Batrachochytrium dendrobatidis (B.d.) may be one of the causes of the enigmatic declines in Mexico. We surveyed a total of 45 localities, in 12 states across Mexico, examining a total of 360 specimens representing 14 genera and 30 species. We also examined 91 specimens of Ambystoma mexicanum from a captive population in Mexico City as well as one Pachymedusa dacnicolor obtained in a pet shop. We used a two-tiered technique to detect the pathogen. For wild-caught specimens, we utilized light microscopy to identify presence of B.d. sporangia in amphibian skin. Then, to verify the infection, we used a quantitative real-time PCR assay on collected skin sections which is specific for B.d. For captive animals, we used a nonlethal version of the real-time PCR technique. We found evidence of B.d. infection in 111 animals comprising 14 species in 13 localities. A large percentage (84%) of Ambystoma mexicanum from the colony were infected with B.d. The two most highly infected individuals were the endangered Ambystoma mexicanum, from a captive colony, and Pachymedusa dacnicolor, purchased at a pet shop.