clutch size

Nanoplastics (NPs) have gained increasing attention due to their widespread presence in aquatic environments and potential adverse effects on organisms. The interaction between NPs and freshwater gastropods can lead to a range of physiological and reproductive disturbances. In this study, we investigated the adverse effects of NPs (two size: 20 nm and 100 nm; three concentrations: 0.5, 50 and 100 ppm) on energy metabolism and reproductive fitness in freshwater gastropods Lymnean stagnalis after 21 days exposure...

Herein, we describe a new species of terrestrially-nesting fanged frog from Sulawesi Island, Indonesia. Though male nest attendance and terrestrial egg deposition is known in one other Sulawesi fanged frog (Limnonectes arathooni), the new species exhibits a derived reproductive mode unique to the Sulawesi assemblage; male frogs guard one or more clutches of eggs festooned to leaves or mossy boulders one to two meters above small slow-moving streams, trickles, or seeps. This island endemic has thus far been collected at three sites on Sulawesi: one in the Central Core of the island, and two on the Southwest Peninsula-south of the Tempe Depression (a major biogeographical boundary)...

Urbanization alters natural habitats, restructures biotic communities and serves as a filter for selecting species from regional species pools. However, empirical evidence of the specific traits that allow species to persist in urban areas yields mixed results. More importantly, it remains unclear which traits are widespread for species utilizing urban spaces (urban utilizers) and which are environment-dependent traits. Using 745 bird species from 287 university/institute campuses in 74 cities and their species pools across China, we tested whether species that occur in urban areas are correlated with regards to their biological (body mass, beak shape, flight capacity and clutch size), ecological (diet diversity, niche width and habitat breadth), behavioural (foraging innovation) and evolutionary (diversification rate) attributes...

In animals, the success of particular lineages can be measured in terms of their number of species, the extent of their geographic range, the breadth of their habitats and ecological niches, and the diversity of their morphological and life-history traits. Here, we review the distribution, ecology, morphology and life history of skinks, a diverse lineage of terrestrial vertebrates. We compared key traits between the three subfamilies of skinks, and between skinks and non-scincid lizards. There are currently 1743 described species of skink, which represent 24% of global lizard diversity...

Long-term monitoring programs are valuable in assessing population trends and evaluating conservation status especially for threatened species exhibiting delayed maturity such as marine turtles. The loggerhead sea turtle Caretta caretta is a globally distributed species with a regional population within the Mediterranean Sea. Loggerhead nesting in the Mediterranean occurs mainly in the eastern basin, with nesting areas classified as per their magnitude and density. A "moderate-dense" nesting area in Greece is the 2...

Long-term avian nesting data are valuable to researchers studying various aspects of avian ecology, conservation, and management. Administered by the Cornell Lab of Ornithology, NestWatch accepts nesting data from volunteers and professionals who agree to follow its protocol and submit data in a standardized form using either the website NestWatch.org, the mobile app, or a bulk upload template. These data (N = 574,288 nest records currently spanning 1874-2023) have been used to examine geographical and temporal variation in breeding success, clutch size, nesting phenology, and other metrics of interest to researchers...

Reproductive investment, including the number of offspring produced, is one of the fundamental characteristics of a species. It is particularly important for island vertebrates, which face a disproportionate number of threats to their survival, because it predicts, among other things, a species' resilience to environmental disruption. Taxa producing more offspring recover more quickly from environmental perturbations and survive environmental change better. However, ecologists do not understand which primary drivers shape a species' reproductive investment well...

In the design of prosthetic hand fingers, achieving human-like movement while meeting anthropomorphic demands such as appearance, size, and lightweight is quite challenging. Human finger movement involves two distinct motion characters during natural reach-and-grasp tasks: consistency in the reaching stage and adaptability in the grasping stage. The former one enhances grasp stability and reduces control complexity; the latter one promotes the adaptability of finger to various objects. However, conventional tendon-driven prosthetic finger designs typically incorporate bulky actuation modules or complex tendon routes to reconcile the consistency and adaptability...

Egg rejection is an effective and widespread antiparasitic defense to eliminate foreign eggs from the nests of hosts of brood parasitic birds. Several lines of observational and critical experimental evidence support a role for learning by hosts in the recognition of parasitic versus own eggs; specifically, individual hosts that have had prior or current experience with brood parasitism are more likely to reject foreign eggs. Here we confirm experimentally the role of prior experience in altering subsequent egg-rejection decisions in the American robin Turdus migratorius , a free-living host species of an obligate brood parasite, the brown-headed cowbird Molothrus ater ...

The working performance and service life of the two-speed transmission system directly affects the performance and service life of helicopters and other equipment. One of the main tasks of the two-speed transmission system research is to improve its dynamic characteristics. For the two-speed transmission system in high-speed gear, a purely torsional nonlinear dynamic differential equation set considering the number of planetary gears, backlash, and clutch dynamic load is established by using the lumped parameter method, and the equations are dimensionless...

Heterosis is the major benefit of crossbreeding and has been exploited in laying hens breeding for a long time. This genetic phenomenon has been linked to various modes of nonadditive gene action. However, the molecular mechanism of heterosis for egg production in laying hens has not been fully elucidated. To fill this research gap, we sequenced mRNAs and lncRNAs of the ovary stroma containing prehierarchical follicles in White Leghorn, Rhode Island Red chickens as well as their reciprocal crossbreds that demonstrated heterosis for egg number and clutch size...

The present study examined how climate changes may impact the concentrations of lipophilic organochlorines (OCs) in the blood of fasting High Arctic common eiders (Somateria mollissima) during incubation. Polychlorinated biphenyls (PCBs), 1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE), hexachlorobenzene (HCB) and four chlordane compounds (oxychlordane, trans-chlordane and trans- and cis-nonachlor) were measured in females at chick hatching (n = 223) over 11 years (2007-2017). Firstly, median HCB and p,p'-DDE concentrations increased ~75 % over the study period, whereas median chlordane concentrations doubled (except for oxychlordane)...

The first-year survival alters population growth rates and viability in birds, however this period remains the least-studied of the avian life stages. Here we present results of the 19 years of study of fledglings apparent survival of urban population of European blackbird Turdus merula in Szczecin (NW Poland). We checked for possible influence on survival of several factors, including parental traits, such as parental age, their previous breeding experience, natal brood size, presence of another brood in a given breeding season and the time gap between clutches of a particular pair...

The variation in egg and clutch mass in sympatric species at high altitudes is poorly understood, and the potential causes of variation are rarely investigated. This study aimed to describe the interspecific variation in avian egg and clutch mass among 22 sympatric bird species at an altitude of 3430 m. Our objective was to reduce potential confounding effects of biotic/abiotic factors and investigated hypotheses concerning allometry, clutch size, parental care, nest predation, and lifespan as possible correlates and explanations for the observed variation...

According to the alternative prey hypothesis (APH), the temporal synchrony in population fluctuations of microtine rodents and other small herbivores in boreal areas is caused by generalist predators with numerical and functional response to microtines, leading to an increased predation of prey alternative to microtines in the low phase of the microtine population fluctuations. The tree-climbing pine marten ( Martes martes ) is a food generalist that includes bird eggs among its alternative prey, also eggs of the cavity-nesting common goldeneye ( Bucephala clangula )...

Host-parasite dynamics involve coevolutionary arms races, which may lead to host specialization and ensuing diversification. Our general understanding of the evolution of host specialization in brood parasites is compromised by a restricted focus on bird and insect lineages. The cuckoo catfish (Synodontis multipunctatus) is an obligate parasite of parental care of mouthbrooding cichlids in Lake Tanganyika. Given the ecological and taxonomic diversity of mouthbrooding cichlids in the lake, we hypothesized the existence of sympatric host-specific lineages in the cuckoo catfish...

Cattle egret Bubulcus ibis, feeds on insect pests in many agro-ecosystems. Thus, there is an urgent need to study the breeding chronology of cattle egret, in order to develop suitable protection programs for this beneficial bird to perform its role as abiological control agent in Egyptian agro-ecosystems. The study was conducted at Sharkia Governorate, Egypt, from December 2018 to December 2020; in different habitats (irrigation canals, drainage canals, garbage collection areas and Abbasa ponds). The mean clutch size ranged from 2-5 eggs/nest with an incubation period ranging between 21-25 days...

In wild vertebrates, the increase of breeding success with advancing age has been extensively studied through laying date, clutch size, hatching success, and fledging success. However, to better evaluate the influence of age on reproductive performance in species with high reproductive success, assessing not only reproductive success but also other proxies of reproductive performance appear crucial. For example, the quality of developmental conditions and offspring phenotype can provide robust and complementary information on reproductive performance...

AbstractMany animals lay their eggs in clusters. Eggs on the periphery of clusters can be at higher risk of mortality. We asked whether the most commonly occurring clutch sizes in pentatomid bugs could result from geometrical arrangements that maximize the proportion of eggs in the cluster's interior. Although the most common clutch sizes do not correspond with geometric optimality, stink bugs do tend to lay clusters of eggs in shapes that protect increasing proportions of their offspring as clutch sizes increase...

After an overview of the discussion about the existence of intra- and interspecific competition that illustrates the contradictory opinions I conclude that long-term field experiments are needed for firm conclusions. I discuss in some detail the role of two factors that limit population size of secondary cavity nesting birds e.g. territorial behavior and adequate cavities. This is followed by an overview of experimental long-term field studies in Belgium showing that intra- and interspecific competition in a great tit-blue tit system exists...