Long-term research on the evolution and ecology of bats
Adaptation in face of environmental change
Enquiries can be directed to Prof. Leandro R. Monteiro: lrmont(at)uenf.br
10-Year milestone reached!! Read our recap of the project during this period.
Long-term studies are crucial for understanding population dynamics and the evolutionary processes responsible for the diversity of life. The evolutionary responses of populations in the presence of environmental fluctuations can be assessed by the temporal variation in fitness, which represents the integration of the number of descendants produced throughout life, a combination of survival and reproduction. This project aims to understand the ecological and evolutionary processes involved in adaptive responses of bats (survival and reproduction), in relation to environmental changes, combining phenotypic markers and long-term population demographic studies. To accomplish this purpose, we monitor a population of the bat Carollia perspicillata, starting in 2013, to establish a long temporal series of capture histories. Bats are important model systems in different areas of evolution, ecology and even human health. These animals perform ecosystem services for population control, dispersion and pollination, in addition to acting in the regulation of emerging diseases. The knowledge about the ecology and evolution of this group has the potential for theoretical developments (basic science) and practical applications in conservation and human health.
Carollia perspicillata is distributed along the Neotropical region, and is dominant throughout its range, due to a high tolerance of environmental disturbance. Its diet is mainly composed of Piper infructescences, a pioneer plant that is common in areas in regeneration. It commonly roosts inside hollow trees, caves or human constructions, such as bridges or abandoned buildings. These bats form reproductive groups that can be composed of one male and a few females and their offspring. A number of males, however, remain in peripheral areas of the colony and take advantage of opportunistic mating to gain reproductive success.
Mark-recapture study
Since 2013, our long term project studies Carollia perspicillata colonies from União Biological Reserve (Rio de Janeiro). The animals are individually marked and, when recaptured, we always record their body weight, reproductive state, age category, forearm lengths and, in the case of males, testicle size. Capture history can be used in mathematical models to estimate survival probability in relation to individual morphological and functional attributes, along with weather variables (rain, temperature) and food availability. Our first results were summarized in Monteiro et al. (2019).
Captures
The bats are captured with hoop nets, inside roosts, or with mist nets, during flight. Individuals are marked, measured and then released.
How are individuals marked?
From 2013 to 2016, each individual was marked with an aluminum band on the forearm. Starting in 2016, we also began marking the bats with surgical steel ball collars. Collars and bands have specific numbers for each individual. Our results (Mellado et al., 2022) showed that forearm bands have a higher potential to cause injury to animals. Therefore, starting in 2022, we began tagging animals by injecting microchips (PIT Tags) under the skin, which have a unique 15-digit number and are read electronically at the time of capture. The double marking with collars and microchips allow for an estimate of tag loss and avoids biases in demographic parameter estimates.
Some famous bats
Blue001: First captured and marked male of C. perspicillata. The first picture shows the day of the capture, still attached to his mother (Pink001, first female captured and marked). He was then recaptured in the same roost eight times between January 2013 and April 2015, when his roost stopped being monitored. The first capture was at mid January 2013, only a few weeks after his birth. In April 2013 he was already considered sub-adult based on the ossification of phalanges. In September 2013, his testicles were larger than 6 mm (in breeding condition). By the end of his first year, he was already able to reproduce. His recapture pattern from 2014 and 2015 suggests it was not yet established as a harem male, when it stopped being monitored.
Pink001: First marked female and mother of Blue001. She was recaptured 12 times from January 2013 until April 2015, when her roost stopped being monitored. Right after the birth of Blue001 she was pregnant again, being recaptured in April 2013 in advanced pregnancy stage. In 2014 and 2015 the pattern of having two pups per reproductive season continued.
AmarPl061: Individual nicknamed as Brachiotys (small eared), due to his ears being shorter than normal. He received initially a forearm band and was recaptured 13 times from October 2015 until October 2018. His first capture as an adult was not really the first capture, as we noticed he presented a forearm band scar. He was recaptured several times during the dry season inside the shelter and presented large testicles, suggesting it was a territorial male that was defending his territory. It is difficult to know what are the causes for the short ears, but their shape and symmetry suggest a congenital or genetic cause. His short ears definitely did not prevented him from being one of the dominant males in the colony.
Blue177: Male individual first captured in February 2016. He was a juvenile, born in late 2015, early 2016. He was recaptured 20 times, the last time in June 2021, when he was 5 years old. In this period, his dentition was already showing signs of advanced age, with broken canines (one of them quite blackened) and worn molars. So many recaptures ended up making the Blue177 also participate in several experiments, to analyze flight performance, bite force and immune response. Besides its longevity, its functional performance was always above that of other males. A peculiarity of Blue177 was the great asymmetry measured between his right and left forearms, which reached 1 millimeter of difference. Considering the statistical relationship between forearm asymmetry and survival and reproduction (reported in Monteiro et al., 2019), Azul177 is the exception that confirms the rule. Its asymmetry was probably not due to a developmental instability.
Pink320: It was first captured in February 2016, already an adult and lactating. Until May 2023, it was captured 18 times, with evidence of 13 pregnancies. Twice she was captured carrying a pup, as in the photo to the left. At 8-9 years of age, it still shows no signs of reproductive senescence, having two young (maximum annual number) by 2023. She is by far the oldest animal (female or male) in the study. We keep hoping that it will continue to break records.