It has been shown that seasonal changes, especially in arid areas have a large influence on gonadal changes of the species that inhabit these areas. We studied a wild hystricomorph Microcavia australis in its natural habitat in the arid Andes Mountains. Sampling of adult males was carried out every 2 months. After autopsy, testes and epididymides were weighed and processed to obtain histological samples. Testes were analyzed with a microscope to measure seminiferous tubule area and diameter for each sampled month. Epididymides were used to determine spermatozoon storage in the cauda region. Results illustrate morphological changes in the testis and epididymis along the year. A high output of sperm cells was detected from middle winter to middle summer and a complete shutdown of spermatogenesis at the end of summer. The initiation of testicular activity coincided with month with the shortest day length, in dry season and very low temperature. On the other hand, gonadal regression started in the middle of summer with long day length, in the wet season, and high temperatures. Rainfall, temperature, and day length seem to be important for the testis cycle. We suggest that photoperiod could be a good predictor for an oncoming period suitable for breeding, and males may probably use it as a signal to regulate gonadal activity.
The quantity component of effectiveness of seed dispersal by animals is determined by two events: fruit removal (intensity of the interaction) and animal visitation to the plant (frequency of interactions). Considering dispersal of Prosopis flexuosa seeds as case study, this work aimed at investigating the strengths and weaknesses of the two methods for assessing the quantity component of seed dispersal effectiveness: exclosures and camera traps. Prosopis fruits were offered for 48 hr. Exclosure treatments were performed using two types of wire‐screen cages, allowing access to ants (“closed exclosure”) and to small mammals up to 100 g (“open to small mammals”), and a treatment without exclosure (“open to all removers”). The camera trapping experiment was carried out using vertically oriented cameras placed at approximately 1.80 m height and focused on the fruits. The cameras were set in “motion detect mode,” taking series of three consecutive photographs. The exclosures largely allowed estimation of fruit removal by size‐based groups of animals, but did not provide information on species identity. In contrast, camera traps were able to identify all visitors to species level and could not only determine the number of visits by each species but also the proportion of visits, which resulted in removal of fruits. Camera trapping allowed discriminating among small mammals playing different roles, without underestimating fruit removal by scatter‐hoarding species. The quality of estimation of the quantity component of seed dispersal is remarkably better when the camera trapping method is applied. Additional information obtained, such as activity patterns of visitors, can contribute to a better understanding of the seed dispersal process.
Artículo publicado en Open Access bajo los términos de Creative Commons attribution Non Comercial License 3.0. MONOGRÁFICO: Frutos, semillas, y mamíferos frugívoros: diversidad funcional en interacciones poco estudiadas ecosistemas REVISTA CIENTÍFICA DE ECOLOGÍA Y MEDIO AMBIENTE
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