The Chiropteran Brain Database: Volumetric Survey of the Hypophysis in 165 Species

Abstract

For nearly two decades, a database of brain structures from a large sample (272 species) of chiropterans has been widely accessible and used for socioecological analyses of mammals. However, this database remains incomplete since the hypophysis has not been measured. Since this glandular/neural structure has reproductive significance to chiropterans as for other mammals, this investigation was carried out using serial coronal sections of bat brains comprising the Heinz Stephan collection, D€ usseldorf, Germany. Complete serially sectioned brains were examined in 313 individuals (165 species, 15 families). Using a well-documented method, hypophyseal volumes were determined from every fourth or sixth section in each individual. The strongest correlation was between body weight and the hypophysis (R 2 5 0.887) and its various components as well as between body weight and adenohypophysis (R 2 5 0.830) and neurohypophysis (R 2 5 0.925). Correlations were also strong for brain weight-adenohypophysis (R 2 5 0.817) and brain weight-neurohypophysis (R 2 5 0.911). Results indicated that: (1) in regression analyses, hipposiderids stand apart as having relatively large adenohypophysis; (2) analysis of residuals generated using least-squares regression of hypophyseal components suggests a trend among microchiropterans where females have a relatively larger adenohypophysis than males. However, this difference is only statistically significant in the largest samples: Phyllostomidae and Vespertilionidae. Pteropodids do not appear to follow this trend. Our findings suggest both phylogenetic and sexual differences in the adenohypophysis in particular, and indicate the need for investigation of larger samples by species, especially those best understood in reproductive and social biology. Anat Rec,

Endocranial Cast Anatomy of the Extinct Hipposiderid Bats Palaeophyllophora and Hipposideros (Pseudorhinolophus) (Mammalia: Chiroptera)

“…One should therefore remain cautious regarding interpretations on these measures. Regarding olfactory bulbs volume, we used the datasets of Baron et al (1996) and of Bhatnagar et al (2016), which include more than 270 extant species, and we added values for our fossil species (ESM2: Table SI. 3).…”

“…Among mammals, bats are a remarkable group by their crucial contribution to extant mammal diversity (second most diverse order, e.g., Teeling 2009) and by their unique ecological specializations towards sustained flight combined with the ability to echolocate (e.g., Teeling et al 2000). The specificity of their ecology is reflected by their brain anatomy, which has been documented for several extant species (e.g., Larsell and Dow 1935;Eisenberg and Wilson 1978;Jolicoeur et al 1984;Baron et al 1996;Safi et al 2005;Bhatnagar et al 2016). However, surprisingly, the evolutionary history of the brain characteristics of Chiroptera has barely been discussed.…”