Born without night: The consequence of the no-night environment on reproductive performance in diurnal zebra finches

We investigated the consequence of no night environment (constant light, LL) on reproductive performance in zebra finches in the parent (P) and subsequent F1 generation. As a measure of the overall effects on the metabolic reproductive health, we monitored daily activity behaviour, recorded song and cheek patch size in males, and measured body size and hormone levels. As compared to controls under 12 h light: 12 h darkness (12:12 h LD), both P and F1 pairs showed a compromised reproductive success, as evidenced by fewer fledglings and viable offsprings with longer fledging durations, and increased offspring mortality with successive three clutches under LL. The overall negative effect of the no-night environment was increased in the F1generation. As compared to P pairs, F1pairs had more failed nesting and breeding attempts, took longer to initiate reproduction, incubated fewer eggs, produced fewer viable offspring with longer fledging duration, and showed increased offspring mortality. Consistent with negative reproductive effects, P males showed significant changes in the motif duration and other spectral features of song, and both F1 and F2 males copied poorly the song of their parent under LL. Plasma corticosterone and sex hormones (testosterone in males and estradiol in females) levels were significantly lower under LL. Daily plasma melatonin rhythm persisted but with a reduced amplitude under LL. These results demonstrate the importance of night in reproduction in a continuously breeding diurnal species, and give insights into the possible impact on physiology of animals whose surrounding environment is consistently losing the darkness of night.

Color, activity period, and eye structure in four lineages of ants: pale, nocturnal species have evolved larger eyes and larger facets than their dark, diurnal congeners

The eyes of insects display an incredible diversity of adaptations to enhance vision across the gamut of light levels that they experience. One commonly studied contrast is the difference in eye structure between nocturnal and diurnal species, with nocturnal species typically having features that enhance eye sensitivity such as larger eyes, larger eye facets, and larger ocelli. In this study, we compared eye structure between workers of closely related nocturnal and diurnal above ground foraging ant species (family Formicidae) in four genera (Myrmecocystus, Aphaenogaster, Temnothorax, Veromessor). In all four genera, nocturnal species tend to have little cuticular pigment (pale), while diurnal species are fully pigmented (dark), hence we could use cuticle coloration as a surrogate for activity pattern. Across three genera (Myrmecocystus, Aphaenogaster, Temnothorax), pale species, as expected for nocturnally active animals had larger eyes, larger facet diameters, and larger visual spans compared to their dark, more day active congeners. This same pattern occurred for one pale species of Veromessor, but not the other. There were no consistent differences between nocturnal and diurnal species in interommatidial angles and eye parameters both within and among genera. Hence, the evolution of eye features that enhance sensitivity in low light levels do not appear to have consistent correlated effects on features related to visual acuity. A survey across several additional ant genera found numerous other pale species with enlarged eyes, suggesting these traits evolved multiple times within and across genera. We also compared size of the anterior ocellus in workers of pale versus dark species of Myrmecocystus. In species with larger workers, the anterior ocellus was smaller in pale than in dark species, but this difference mostly disappeared for species with smaller workers. Presence of the anterior ocellus also was size-dependent in the two largest pale species.

Raptors of A Neotropical City: Diversity And Habitat Relationships Along An Urbanization Gradient

Urbanization involves changes in landscape terrain, hydrology, and vegetation. These changes allow some wildlife species to thrive in cities while blocking others. We analyzed how a gradient of urbanization in the city of Xalapa could have a filtering effect that prevents some raptors from occurring or effectively use the most urbanized areas, and where such filtering effects occur. We selected 6 habitat variables that could predict the detection and occupation of raptors along the urban gradient. We conducted direct observations and call-broadcast surveys to estimate relative abundance, richness, and diversity of raptors from June 2019–February 2020. We visited 20 sites during three seasons, from dawn–11:00 and 18:00–23:00 h. We obtained 201 individual records of 14 species. The best-preserved part of the gradient (< 7.7% urban cover) had the highest species diversity, while the 4th category along the gradient (53.9% urban cover) had the lowest, suggesting that at this level of urbanization an abrupt filtering effect occurs on the raptor community. The proportion of exotic/native plant species was the best detection predictor for most of the diurnal species and Ciccaba virgata. The proportion of urban relative to green area was negatively associated with the occupation of Accipiter cooperii and Rupornis magnirostris. Our results suggests that this Neotropical city effectively acts as a filter for most species, with only 4 raptors able to use or occupy most of the urban gradient. Our work represents a critical first step towards understanding how the process of urbanization influences a raptor community.

Global patterns of raptor distribution and protected areas optimal selection to reduce the extinction crises

Globally, human-caused environmental impacts, such as habitat loss, have seriously impacted raptor species, with some 50% of species having decreasing populations. We analyzed global patterns of distribution of all 557 raptor species, focusing on richness, endemism, geographic range, conservation status, and population trends. Highest species diversity, endemism, species at risk, or restricted species were concentrated in different regions. Patterns of species distribution greatly differed between nocturnal and diurnal species. To test the efficiency of the global protected areas in conserving raptors, we simulated and compared global reserve systems created with strategies aiming at: 1) constraining the existing system into the final solution; and 2) minimizing the socioeconomic cost of reserve selection. We analyzed three targets of species distribution to be protected (10, 20, 30%). The first strategy was more efficient in meeting targets and less efficient in cost and compactness of reserves. Focusing on actions in the existing protected areas is fundamental to consolidate conservation, and politically and economically more viable than creating new reserves. However, creating new reserves is essential to protect more populations throughout the species’ geographic range. Our findings provide a fundamental understanding of reserves to maintain raptor diversity and reduce the global population and species extinction crisis.

Dung beetle community assemblages in a southern African landscape: niche overlap between domestic and wild herbivore dung

Dung beetles provide important ecosystem functions in semiarid environments, improving the physiochemical characteristics of the soil through tunnelling and burying nutrient-rich dung. In sub-Saharan Africa, diverse indigenous mammal communities support highly abundant dung beetle populations in savannah ecosystems. However, the conversion of landscapes to livestock agriculture may result in changes in the abundance and diversity of wild mammal species. This is likely to have significant impacts on dung beetle communities, particularly because domestic livestock dung may be contaminated with toxic residues of veterinary parasiticides. The environmental impact is likely to be affected by the degree of niche overlap between the beetle communities that colonize cattle dung and those that colonize the dung of wild mammals. We compared dung beetle communities between a pristine national park habitat dominated by large wild herbivores, and a pastoral farming community dominated by domestic livestock. Diurnal dung beetles were attracted to cattle dung in greater abundance and diversity compared to elephant, zebra or giraffe dung. Nocturnal/crepuscular dung beetles were attracted to non-ruminant dung (elephant and zebra) in higher abundance compared to ruminant dung (cattle and giraffe). Although there were no clear trophic specializations, three diurnal species showed an association with cattle dung, whereas eight nocturnal/crepuscular species showed an association with non-ruminant (elephant and zebra) dung. Diurnal species may be at greater risk from the toxic effects of residues of veterinary parasiticides in domestic livestock dung. Although many species showed trophic associations with wild herbivore dung, these beetles can utilize a wide range of dung and will readily colonize cattle dung in the absence of other options. As more land is converted to livestock agriculture, the contamination of dung with toxic residues from veterinary parasiticides could therefore negatively impact the majority of dung beetle species.

Does colour impact attention towards 2D images in geckos?

Animals are exposed to different visual stimuli that influence how they perceive and interact with their environment. Visual information such as shape and colour can help the animal detect, discriminate and make appropriate behavioural decisions for mate selection, communication, camouflage, and foraging. In all major vertebrate groups, it has been shown that certain species can discriminate and prefer certain colours and that colours may increase the response to a stimulus. However, because colour is often studied together with other potentially confounding factors, it is still unclear to what extent colour discrimination plays a crucial role in the perception of and attention towards biologically relevant and irrelevant stimuli. To address these questions in reptiles, we assessed the response of three gecko species Correlophus ciliatus, Eublepharis macularius, and Phelsuma laticauda to familiar and novel 2D images in colour or grayscale. We found that while all species responded more often to the novel than to the familiar images, colour information did not influence object discrimination. We also found that the duration of interaction with images was significantly longer for the diurnal species, P. laticauda, than for the two nocturnal species, but this was independent from colouration. Finally, no differences among sexes were observed within or across species. Our results indicate that geckos discriminate between 2D images of different content independent of colouration, suggesting that colouration does not increase detectability or intensity of the response. These results are essential for uncovering which visual stimuli produce a response in animals and furthering our understanding of how animals use colouration and colour vision.

Nocturnal singing by diurnal birds in Afrotropical highlands

Most bird species are active by day. However, even typically diurnal species have been observed to sing by night, although the functions and mechanisms of this behaviour are not well understood. In our study, we focused on nocturnal singing by diurnal birds in Afrotropical highlands (Bamenda Highlands, Cameroon). We recorded 48-h soundscapes in 18 random recording sites using autonomous sound recorders to examine the occurrence and intensity of nocturnal singing among diurnal birds. We applied three definitions of night—the time period between: (1) astronomical, (2) nautical and (3) civil dusk and dawn, which may include or exclude beginning of dawn chorus from the night-time period. We recorded 53 bird species, representing seven orders and 27 families. Of 50 typically diurnal species, only three sang by astronomical night, producing in total 10 songs. Applying the nautical night definition did not change the meaning of the results—the same three species produced 12 vocalisations. By civil night, 21 species were recorded singing. From the analysed 2128 vocalisations produced by civil night, 2109 were produced during 25 min period between nautical and civil dawn (22–47 min before sunrise), what suggests that civil night covers the beginning of dawn chorus and should not be considered as a nighttime. Our study reveals that in Afrotropical highlands, unlike in temperate regions, diurnal birds stay silent at night. Using astronomical and nautical definition of night gives similar results. The intensive singing recorded between nautical and civil dawn (included into nautical night), we interpreted as the beginning of dawn chorus rather than true night singing. We suggest that precise definition of nighttime is required to compare the results of different studies and to better understand the phenomenon of night singing by diurnal birds.

KEANEKARAGAMAN JENIS BURUNG DIURNAL DI HUTAN JAJAU KECAMATAN MENTEBAH KABUPATEN KAPUAS HULU KALIMANTAN BARAT

Mentabah sub-district is one of the territories in Kapuas Hulu, the province of West Borneo. The width is about 781,26 km² with enormous potential for biodiversity. One of them is Jajau forest. The local people called it Jajau Forest that also known as Kerangas forest. The purpose of this research is to collect data about the diversity of Diurnal species in Jajau Forest in Mentabah sub-district, Kapuas Hulu, the province of West borneo. IPA ((Index Point Abundance) is used in this research that placed purposively. The result of this research shows that there are 111 birds species could be indetified with 938 birds include 39 families. This research showh that the variety of birds in this are is so high, it is 4.4221.Keywords: diversity of birds, Jajau Forest, Mentebah District

Speed of phototransduction in the microvillus regulates the accuracy and bandwidth of the rhabdomeric photoreceptor

Phototransduction reactions in the rhabdomeric photoreceptor are profoundly stochastic due to the small number of participating molecules and small reaction space. The resulting quantum bumps (QBs) vary in their timing (latency), amplitudes and durations, and these variabilities within each cell are not correlated. Using modeling and electrophysiological recordings, we investigated how the QB properties depend on the cascade speed and how they influence signal transfer. Parametric analysis in the model supported by experimental data revealed that faster cascades elicit larger and narrower QBs with faster onsets and smaller variabilities than slower cascades. Latency dispersion was stronger affected by modification of upstream than downstream activation parameters. The variability caused by downstream modifications closely matched the experimental variability. Frequency response modeling showed that corner frequency is a reciprocal function of the characteristic duration of the multiphoton response, which, in turn, is a non-linear function of QB duration and latency dispersion. All QB variabilities contributed noise but only latency dispersion slowed and spread multiphoton responses, lowering the corner frequency. Using the discovered QB correlations, we evaluated transduction noise for dissimilar species and two extreme adaptation states, and compared it to photon noise. The noise emitted by the cascade was non-additive and depended non-linearly on the interaction between the QB duration and the three QB variabilities. Increased QB duration strongly suppressed both noise and corner frequency. This trade-off might be acceptable for nocturnal but not diurnal species because corner frequency is the principal determinant of information capacity. To offset the increase in noise accompanying the QB narrowing during light adaptation and the response-expanding effect of latency dispersion, the cascade accelerates. This explains the widespread evolutionary tendency of diurnal fliers to have fast phototransduction, especially after light adaptation, which thus appears to be a common adaptation to contain stochasticity, improve SNR and expand the bandwidth.