Growth and Development of Two Species of Bats in a Shared Maternity Roost

Abstract

Skeletogenesis was studied in two species of bats, Myotis austroriparius (southeastern brown bat) and Tadarida brasiliensis (Brazilian free-tailed bat), occupying a maternity roost in central Florida. These bats often use distinct maternity roost environments, so this provided an opportunity to examine differential patterns of long bone growth while fetuses and newborn developed under similar environmental conditions. Some differences in the timing of onset of osteogenesis were revealed in the bats, indicating that some elements of the hindlimb develop relatively more rapidly in T. brasiliensis than in M. austroriparius. Some variance was also noted, with similarity to other species previously studied by others, in the exact timing and elongation of both long bones, as well as carpal and tarsal bones. In contrast to many elements of the long appendicular skeleton of developing Mus musculus, the bats all exhibit relatively precocial patterns of osteogenesis during which cartilaginous precursors are replaced by bone tissue. The relative advanced timing of osteogenesis in select hindlimb bones of T. brasiliensis may account for its relatively low neonatal mortality compared to M. austroriparius newborn in the same roost.

Unique near isometric ontogeny in the pterosaurRhamphorhynchussuggests hatchlings could fly

“…This is corroborated by comparative osteological data (Figs 1, 2; ESM4). In non-flying newborn and juvenile bats, leg bones exhibit greater ossification than wing bones (Hermanson & Wilkins 2008) corroborating observations that juvenile bats first climb and only later fly (Norberg & Rayner 1987). Similarly, in gulls, hindlimb bones ossify earlier than do forelimb bones (Starck & Ricklefs 1998).…”

“…Specimens were collected, fixed and preserved as described in Hermanson & Wilkins (2008). We confirmed measurements from Hermanson & Wilkins (2008) and took additional measures of the metacarpal and first and second phalanges of the third finger (the digit that extends to the wingtip and is thus representative of span). To compare wingspan and wing loading estimates from R. muensteri specimens across their size range to those of fast-hawking open-space adult bats of different size but similar morphology, we used species, and used wing loading and wingspan data for free-tailed bats (Molossidae) available in Norberg & Rayner (1987).…”

Is tissue maturation necessary for flight? Changes in body composition during postnatal development in the big brown bat

“…Histological data for three additional insectivorous bat species support this result; the level of ossiWcation observed in several skeletal elements of the little brown myotis (Myotis lucifugus), southeastern myotis (Myotis austroriparius), and Brazilian free-tailed bat (Tadarida brasiliensis) are greater at birth than the house mouse and Norway rat at or near weaning (Adams 1992;Hermanson and Wilkins 2008;Patton and Kaufman 1995). Hermanson and Wilkins (2008) described considerable variation in the degree of ossiWcation for diVerent bones in late embryological and early neonatal development in the southeastern myotis and Brazilian freetailed bat. Thus, a relatively high total body concentration of calcium need not indicate high levels of mineralization for all bones.…”

Secondary ossification center induces and protects growth plate structure

“…It was apparent during ontogenesis and consistent within the Chiroptera order (summary of 6 species with available ontogeny data is presented in Figure 2D-E and primary data for all 13 species analyzed presented in Supplementary File 1). It has to be admitted that despite a very clear pattern of heterochrony there is a variation of ossification among Chiroptera species, which likely reflects their varying foraging and roosting ecology, behavior of juvenile bats, litter size, and lifespan (19)(20)(21)(22)(23).…”