Microtis

Abstract: Flightless worker ants of the species complex Iridomyrmex gracilis (Lowne) are effective pollinators of Microtis parviflora R.Br. in the Castlereagh Forest near Sydney. Field and laboratory observations and experiments showed that this orchid is self-compatible but not autogamous and ant pollination results in very high levels of seed set. This is the first study to show that wingless ants can be exclusive pollinators. Ants forage persistently, visiting individual flowers and inflorescences repeatedly for nectar. Foraging patterns most likely result in high levels of selfing, but leptokurtic distributions of pollinator travel distances suggest that some pollen transfers result in cross pollination. Microtis pollen carried by I. gracilis workers is unaffected by antibiotic secretions from the metapleural glands which, in other ant species, may reduce pollen viability drastically. Pollinia are separated from the ant integument by a short stalk and are always carried on the frons, remote from the metapleural glands. This study shows that worker ants, although wingless, can be efficient pollinators and suggests that the presence of metapleural glands is not necessarily inimical to the evolution of ant pollination, particularly if mechanisms, such as stalked pollinia, prevent direct contact between ants and pollen. Key-words: Ant, ant foraging, ant pollination, antibiotic, Iridomyrmex, metaplural gland, Microtis, orchid, pollen inhibition, pollination

Abstract: To assess the influence of habitat fragmentation on small bats, we determined home range size and mobility of the frugivorousArtibeus watsoni Thomas, 1901 and the gleaning insectivorousMicronycteris microtis Miller, 1898 by radiotracking on different-sized islands (2.7–17 ha) in Lake Gatun, Panama. The two species differed in their response to fragmentation. Home range size was highly variable in the five trackedA. watsoni, ranging from 1.8 to 17.9 ha with a mean of about 9 ha. Some individuals flew regularly between islands and/or the mainland, thereby traversing up to 180 m of open water. In comparison, home ranges of threeM. microtis were with about 3.8 ha only half as large. All ofM. microtis exhibited sedentary foraging behaviour and did not cross open water, suggesting that they might persist at least on some of the islands as resident populations. Our findings are consistent with radiotracking data from a previous study and indicate that small habitat patches are still used by small bats, provided the degree of isolation is low and that sufficient resources and larger habitat patches exist in close vicinity, potentially acting as additional feeding grounds and source populations.

Abstract: We analyzed DNA sequence variation in the cytochrome-b gene and intron 7 of the nuclear fibrinogen, B beta polypeptide gene for 45 specimens of the bat genus Micronycteris, including all currently recognized species except M sanborni Phylogenetic analyses of both data sets supported 4 primary lineages within Micronycteris, which we recognize as subgenera: Leuconycteris new subgenus (M brosseti), Micronycteris Gray (M megalotis, M microtis, M matses, and M giovanniae), Schizonycteris new subgenus (M minuta, M schimdtorum, and M sanborni), and Xenoctenes Miller (M hirsuta) Although we provisionally recognize the current alpha taxonomy within Micronycteris, our results did not support monophyly of M microtis as the name is currently applied Our results further indicate that cryptic species probably exist within the taxa currently recognized as M megalotis and M minuta and possibly M hirsuta Additional studies, including thorough geographic sampling and detailed morphological and molecular data sets, are necessary to test our genealogic hypotheses and assess the biodiversity within Micronycteris

Abstract: Ecological specialization and resource partitioning are expected to be particularly high in the species-rich communities of tropical vertebrates, yet many species have broader ecological niches than expected. In Neotropical ecosystems, Neotropical leaf-nosed bats (Phyllostomidae) are one of the most ecologically and functionally diverse vertebrate clades. Resource partitioning in phyllostomids might be achieved through differences in the ability to find and process food. We selected Micronycteris microtis, a very small (5–7 g) animalivorous phyllostomid, to explore whether broad resource use is associated with specific morphological, behavioral and performance traits within the phyllostomid radiation. We documented processing of natural prey and measured bite force in free-ranging M. microtis and other sympatric phyllostomids. We found that M. microtis had a remarkably broad diet for prey size and hardness. For the first time, we also report the consumption of vertebrates (lizards), which makes M. microtis the smallest carnivorous bat reported to date. Compared to other phyllostomids, M. microtis had the highest bite force for its size and cranial shape and high performance plasticity. Bite force and cranial shape appear to have evolved rapidly in the M. microtis lineage. High performance capacity and high efficiency in finding motionless prey might be key traits that allow M. microtis, and perhaps other species, to successfully co-exist with other gleaning bats.