MICROCLIMATE VERSUS PREDATION RISK IN ROOST AND COVERT SELECTION BY BOBWHITES

Abstract: Knowledge of factors that influence habitat selection by wildlife leads to better understanding of habitat ecology and management. Therefore, we compared microclimate and predation risk as factors influencing the selection of stopping points (mid-day coverts, nocturnal roosts) by northern bobwhites (Colinus virginianus). Stopping points were located using radiomarked bobwhites in the Texas Panhandle, USA, during 2002–2003. We obtained blackbody temperatures of microclimates and assessed predation risk (angles of obstruction for aerial predators, vegetation profiles for terrestrial predators) at stopping points and paired random points. Summer coverts showed fewer degree-minutes of hyperthermic exposure (blackbody temperatures >39°C; x̄ = 655.0, SE = 4.1 for coverts, x̄ = 2,255.5, SE = 4.9 for random; 1200–1600 hr) and a lower risk to predators (e.g., 95% confidence intervals [CIs] of angles of obstruction = 87.8–90.8° for coverts, 55.9–70.6° for random). Summer roost temperatures were similar to paired random sites (x̄ = −13.9°C, SE = 0.6 for roost, x̄ = 13.9°C, SE = 0.7 for random) as were winter roost temperatures (x̄ = −1.3°C, SE = 0.7 for roosts, x̄ = −1.4°C, SE = 0.8 for random). There were minor issues of habitat selection of winter or summer roosts based on predation risk (e.g., 95% CIs of vegetation profiles of summer roosts and random sites did not overlap at lower strata). We concluded other selection factors likely exist for winter roosts because microclimate and predation risk assessments between winter roosts and random sites showed no difference. Similarly, other selection factors may exist for summer roosts, as they showed only a weak difference in terrestrial predation risk and no difference in microclimate in comparison to random sites. We concluded microclimate was the primary selection factor for coverts because prevention of hyperthermia necessitated that bobwhites select cooler microclimates within the study area.     

Phylogenetics and biogeography of the broad-nosed bats, genus Platyrrhinus (Chiroptera: Phyllostomidae)

The Neotropical broad-nosed bats, genus Platyrrhinus, represent a well-defined monophyletic group of 14 recognized species. A recent study of morphological characters confirmed Platyrrhinus monophyly and species diagnosis, but offered little support to their intra-specific relationships. We conducted phylogenetic analyses of the genus, using dense taxonomic sampling in combination with four gene sequences representing both mitochondrial and nuclear DNA transmission systems. Our aim was to elucidate the phylogenetic structure among species, using the resulting 3341 bp of DNA. Maximum parsimony, maximum likelihood, and Bayesian inference analyses produced similar topologies that confirm the monophyly of the genus Platyrrhinus and strongly support many previously unrecognized groups. Paraphyly of Platyrrhinus helleri and the unclear position of P. brachycephalus in the clades were also apparent in the data. Our biogeographical analysis suggests a Brazilian Shield origin for Platyrrhinus, followed by subsequent radiations of lineages in the Amazon Basin and Andes. Secondary dispersal from Amazonian and Andean centers is responsible for the Platyrrhinus inhabiting the Guianan Shield and the Pacific lowlands and Central America, respectively.     

大足鼠耳蝠的分布

首次报道北京、成都和广东发现大足鼠耳蝠,并结合文献对其形态特征及其在我国现有分布区进行了描述。     

MHC class II DRB diversity, selection pattern and population structure in a neotropical bat species, Noctilio albiventris

Genes of the major histocompatibility complex (MHC) have a crucial role in the immune response of vertebrates, alter the individual odour and are involved in shaping mating preferences. Pathogen-mediated selection, sexual selection and maternal-fetal interactions have been proposed as the main drivers of frequently observed high levels of polymorphism in functionally important parts of the MHC. Bats constitute the second largest mammalian order and have recently emerged as important vectors of infectious diseases. In addition, Chiroptera are interesting study subjects in evolutionary ecology in the context of olfactory communication, mate choice and associated fitness benefits. Thus, it is surprising that they belong to the least studied mammalian taxa in terms of their MHC diversity. In this study, we investigated the variability in the functionally important MHC class II gene DRB, evidence for selection and population structure in the group-living lesser bulldog bat, Noctilio albiventris, in Panama. We found a single expressed, polymorphic Noal-DRB gene. The substitution pattern of the nucleotide sequences of the 18 detected alleles provided evidence for positive selection acting above the evolutionary history of the species in shaping MHC diversity. Roosting colonies were not genetically differentiated but females showed lower levels of heterozygosity than males, which might be a sign that the sexes differ in the selection pressures acting on the MHC. This study provides the prerequisites for further investigations of the role of the individual MHC constitution in parasite resistance, olfactory communication and mate choice in N. albiventris and other bats.     

Double meaning of courtship song in a moth

Males use courtship signals to inform a conspecific female of their presence and/or quality, or, alternatively, to ‘cheat’ females by imitating the cues of a prey or predator. These signals have the single function of advertising for mating. Here, we show the dual functions of the courtship song in the yellow peach moth, Conogethes punctiferalis, whose males generate a series of short pulses and a subsequent long pulse in a song bout. Repulsive short pulses mimic the echolocation calls of sympatric horseshoe bats and disrupt the approach of male rivals to a female. The attractive long pulse does not mimic bat calls and specifically induces mate acceptance in the female, who raises her wings to facilitate copulation. These results demonstrate that moths can evolve both attractive acoustic signals and repulsive ones from cues that were originally used to identify predators and non-predators, because the bat-like sounds disrupt rivals, and also support a hypothesis of signal evolution via receiver bias in moth acoustic communication that was driven by the initial evolution of hearing to perceive echolocating bat predators.     

Subcellular preservation in giant ostracod sperm from an early Miocene cave deposit in Australia

Cypridoidean ostracods are one of a number of animal taxa that reproduce with giant sperm, up to 10 000 µm in length, but they are the only group to have aflagellate, filamentous giant sperm. The evolution and function of this highly unusual feature of reproduction with giant sperm are currently unknown. The hypothesis of long-term evolutionary persistence of this kind of reproduction has never been tested. We here report giant sperm discovered by propagation phase contrast X-ray synchrotron micro- and nanotomography, preserved in five Miocene ostracod specimens from Queensland, Australia. The specimens belong to the species Heterocypris collaris Matzke-Karasz et al. 2013 (one male and three females) and Newnhamia mckenziana Matzke-Karasz et al. 2013 (one female). The sperm are not only the oldest petrified gametes on record, but include three-dimensional subcellular preservation. We provide direct evidence that giant sperm have been a feature of this taxon for at least 16 Myr and provide an additional criterion (i.e. longevity) to test hypotheses relating to origin and function of giant sperm in the animal kingdom. We further argue that the highly resistant, most probably chitinous coats of giant ostracod sperm may play a role in delaying decay processes, favouring early mineralization of soft tissue.     

恒频-调频蝙蝠特化的听觉系统对回声定位的适应

在漫长的生物演化过程中,蝙蝠演化出了能飞行和高度适应生存环境的生物声纳系统和行为.蝙蝠属于哺乳动物纲的翼手目(Chiroptera),是唯一能真正飞行的哺乳动物,其种类超过1000种,位列哺乳类动物的第二大目.根据其体型大小和形态特征将其分成大蝙蝠亚目(Megachiroptera)和小蝙蝠亚目(Microchiroptera).对蝙蝠的研究具有重要的科学意义和实际应用价值,如在听感觉方面与人类共享听觉的某些基本原理,研究结果有助于认识人类听觉.它们发出的回声定位信号规整,便于模拟后用于研究听觉系统对声信号加工的机制,尤其是在听中枢对复杂声信号处理方面,认识其细胞和分子机制才刚开始,它们是极好的模型动物.另外,在仿生学方面也具有极其重要的价值,回声定位蝙蝠的生物声纳系统具有极高的时间和空间分辨率,是极具诱惑力的研究课题.有关恒频-调频蝙蝠听觉结构和功能的研究,已有相当的时日,获得了不少新的认识,窥探到敏锐的听觉与回声定位行为之间的某些适应性的机制,本文对这方面的研究进展做了简要介绍和评述.     

皮氏菊头蝠(Rhinolophus pearsoni)的栖息生态特征

皮氏菊头蝠(Rhinolophus pearsoni)是我国南方典型的洞栖食虫性蝙蝠,具有重要的生态意义。近年于湘西州及张家界市的25个溶洞中共记录到该蝠450只次,对其栖息生态特征(空间分布、姿势、体温、栖点温度和栖点安全性等)进行了较为系统的观测。结果表明:该蝠的栖点主要集中分布于离洞口440 m之内的洞段(占99.3%),栖点高度通常介于2—10 m之间(84%),主要采取双足倒挂的姿势栖息于洞顶壁或侧壁,但单足倒挂的栖息姿势也较为常见(36.2%)。体温介于10.7—25.2℃,体温总是稍高于栖点温度,但两者之间无显著性差异(P0.05),且两者呈线性正相关。约64%的栖点"安全性高",而"安全性低"和"安全性中"的栖点分别占17.6%和18.4%。减少对洞穴的人为干扰是保护该物种的有效途径。