Ricardo López-Wilchis

Habitat Variation and Jamming Avoidance in Echolocation Calls of the Sac-winged Bat (Balantiopteryx plicata)

Abstract We have studied the effect of habitat and presence of conspecifics on echolocation characteristics of the emballonurid bat Balantiopteryx plicata. Calls during the search phase only showed differences between habitats in bandwidth, as has been found for other open-space bats. Characteristics of calls during the approach phase did change when bats entered open areas. Calls in the terminal phase showed no differences in the characters examined between habitats. Bats flying in groups shifted their peak frequency significantly, which maximized differences between individuals. These results are interpreted as an active mechanism of jamming avoidance. Bats flying in groups also tended to increase the mean of peak frequencies.

Molecular phylogeography of Pteronotus davyi (Chiroptera: Mormoopidae) in Mexico

Abstract Pteronotus davyi, Davys naked-backed bat, is a tropical bat whose current distribution in Mexico covers the watersheds of the Pacific and the Gulf coasts of Mexico, converges at the Isthmus of Tehuantepec, and continues into the Yucatan peninsula. We evaluated phylogeographic relationships among 18 populations in Mexico using data from the nucleotide sequence of the hypervariable II domain of the mitochondrial DNA control region from 105 specimens. Extant populations were distributed over 3 geographic regions (Pacific Coast, Gulf Coast, and Southeastern) that were delineated a priori according to floristic characteristics and biogeography. Coalescent simulations supported a phylogeographic model of 2 refugia situated in the south of Mexico (Arc and Soconusco refuges) during the late Pleistocene, followed by expansion into Pacific Coast, Gulf Coast, and Southeastern groups. The populations of the Southeast were genetically divergent from the Pacific and Gulf Coast populations, supporting the existence of 2 distinct lineages of P. davyi in Mexico, likely due to the Isthmus of Tehuantepec acting as a geographical barrier. Examination of our data revealed genetic differentiation of the Pacific and Gulf coastal groups but at a lower level relative to the Southeast. This pattern suggests that the Sierra Madre Occidental, Sierra Madre Oriental, and Sierra Madre del Sur act as physical barriers to dispersal for P. davyi.

MALE REPRODUCTIVE CYCLE OF MEXICAN BIG-EARED BATS, CORYNORHINUS MEXICANUS (CHIROPTERA: VESPERTILIONIDAE)

Abstract Morphological observations of male genital tracts obtained from wild, adult Mexican big-eared bats (Corynorhinus mexicanus) revealed only one but long annual reproductive cycle showing the existence of temporal asynchrony of its reproductive functions, as is characteristic of temperate-zone vespertilionid and rhinolophid chiropterans. Testes were largest in August, whereas maximum development of epididymides and accessory sex glands complex was observed 1 and 3 months later. High value of relative body condition of individuals was observed from May to June, when testicular enlargement commenced, suggesting that recrudescence of spermatogenesis in the adult bats is dependent on a good body condition.

Echolocation calls and a noteworthy record of Pteronotus gymnonotus (Chiroptera, Mormoopidae) from Tabasco, Mexico

Echolocation calls of the big naked-backed bat, Pteronotus gymnonotus, are poorly known. At present, only the predominant frequencies have been described from calls emitted by indoor or hand held specimens (Griffin and Novick, 1955; Grinnell, 1970; Simmons, 1973) and a single sonogram (Pye, 1980). We present the first description of echolocation characteristics of P gymnonotus, recorded from a freeflying specimen from Tabasco, Mexico. Distributional implications of this record also are discussed.

Taxonomic Status Assessment of the Mexican Populations of Funnel-Eared Bats, Genus Natalus (Chiroptera: Natalidae)

Due to its morphological conservatism, the American funnel-eared bats of the genus Natalus have had a complex taxonomic history. In Mexico only one species, N. stramineus, has traditionally been recognized. But recently a new endemic species, N. lanatus, was described in the region as a sympatric sibling species of N. stramineus. Natalus stramineus, with a geographic distribution extending from Mexico to Panama, was subsequently reassigned to N. mexicanus. In this study, we analyzed morphological and molecular characters to determine if two distinct species of funnel-eared bats (N. lanatus and N. mexicanus) occur in Mexico. We found that the proposed diagnostic morphological characters that separate the two taxa are not consistent and rarely differentiate between the two forms. Likewise, phylogenetic analyses do not support the separation of Natalus into two species in Mexico, but there is clearly geographic structure when all Mexican haplotypes are combined. The genetic distance between the haplotypes that could be ascribed to N. lanatus and N. mexicanus was typically within the range of conspecifics and not distinct species. To summarize, the results of both morphological and molecular analyses point to the presence of a single species of Natalus in Mexico.

ECHOLOCATION OF THREE SPECIES OF SAC-WINGED BATS (BALANTIOPTERYX )

Abstract We describe and compare field recordings of echolocation calls of the neotropical emballonurid sac-winged bats Balantiopteryx plicata, B. io, and B. infusca. These 3 species have search-phase calls with principal energy in the 2nd harmonic, characterized by a long narrowband component followed by a short broadband component. Variation in call parameters follows only partially the scaling pattern with body size generally found in bats. Based on characteristics of their echolocation calls, we hypothesize that B. io and B. infusca forage in more cluttered habitats than does the congeneric B. plicata, which typically hunts in open areas.

Evolutionary scenarios associated with the Pteronotus parnellii cryptic species-complex (Chiroptera: Mormoopidae).

One of the major challenges to understanding the evolution of Neotropical bats concerns our capacity to successfully scrutinize phylogenetic patterns associated with cases of cryptic species complexes. In this study Pteronotus parnellii is examined as a selected example of a known lineage of mormoopid bat that potentially contains several cryptic species. A samples of 452 individuals from 83 different localities, essentially covering its entire mainland distribution, was evaluated using two genetic markers: COI (mitochondrial) and DBY (nuclear) genes. The findings of this study strongly support the hypothesis of high genetic variability and identify at least six lineages within P. parnellii, some of which appear to be cryptic species.

Specimens of mammals from Mexico in collections in the United States and Canada

We compiled information about Mexican mammals in collections in the United States and Canada. There are 207,067 specimens of Mexican mammals in 78 institutions in these two countries. The number per institution ranges from 1 to 44,221 and 6 collections exceed 10,000 specimens each. These six collections have representatives of nearly all the mammalian species known from Mexico and also have materials from all Mexican states. The orders Rodentia and Chiroptera have the highest numbers of specimens; the orders Perissodactyla and Sirenia have the fewest numbers of specimens. Peromyscus and Perognathus are the genera best represented. Collections in United States and Canada are important to the knowledge of Mexican mammals.

Variations in the locomotor activity of the Mexican wolf (Canis lupus baileyi) respect to moon periodicity: a study in an outdoor enclosure

Abstract It is assumed that the response of the regulatory system of mammal activity depends on the changes in light intensity throughout the 24-h cycle. The aim of this study was to determine whether the moon luminosity cycle exerts an effect on the locomotor activity of the Mexican wolf (C. lupus baileyi). Data collection was carried out with the actimetry, of 11 individuals were analyzed using ANOVA to determine the effect of the lunar cycle. Significant differences were encountered between moon phases (p = 0.001), with a decrement of activity during new and full moon. However, effects were dependent also on the age of the individuals and the daylight period. On the other hand, it is a possible regulation of the activity pattern by the effect of lunar periodicity. This periodicity needs a more detailed examination to determine its adaptive function.

Serotonin in Testes of Bat Myotis velifer During Annual Reproductive Cycle: Expression, Localization, and Content Variations

The mechanism of reproduction in mammals is very complex and in some cases is quite particular. For example in some bat species, the male presents a reproductive mechanism characterized by an annual testicular cycle that goes from recrudescence to regression (spermatogenesis to inactivity period, respectively). After recrudescence, the spermatozoa arrive at epididymis and wait to be expelled at the time of ejaculation during the mating period, which occurs some months later. Because serotonin (5-HT) has gained reproductive importance in the last years, the aim of the present study was to analyze the expression of this indolamine and both tryptophan hydroxylase and monoamine oxidase isoform A-enzymes involved in its metabolism-in Myotis velifer testes, a seasonal reproductive bat species that shows temporal asynchrony in its sexual cycle, across the principal periods of their reproductive cycle. By using both Falck-Hillarp histochemistry and immunofluorescence techniques, we found serotonin in vesicles of Leydig cells and probably Sertoli cells too; interestingly, both intracellular localization and concentration was variable across the different stages of the reproductive cycle, being lower during spermatogenesis phase and increasing during the mating phase. These results suggest that 5-HT is present in bat testes and it could play an important role in testicular function during their reproductive cycle.