Symbiont-driven niche expansion shaped the adaptive radiation of insects

For over 300 million years, insects have relied on symbiotic microbes for nutrition and defence1,2. However, it is unclear whether specific ecological conditions have repeatedly favoured the evolution of symbioses, and how this has influenced insect diversification1,3,4. Using data on 1844 microbe-insect symbioses across 400 insect families, we found that symbionts have allowed insects to radiate into a range of feeding niches deficient in B vitamins, including phloem, blood and wood. In some cases, such as herbivorous insects, the shift to a new niche has resulted in spectacular species proliferation. In other niches, such as strict blood feeding, diversification has been severely constrained. Symbioses therefore appear to solve universal nutrient deficiencies for insects, but the consequences for insect diversification depend on the feeding niche invaded.

The Food of Athene noctua in nocturnal conditions as located in University of Agriculture, Faislabad

This study was primarily focused on determining the availability of feeding niche of the little owl in University Campus. For this purpose, observations were made consecutively on the location of important sites in University Student’s Farm. This Farm is characterized by different types of tree species. Some of the important ones comprise Salmalia malabarica, Dalbergia sissoo, Cedrella toona, Terminalia arjuna and few others. The little owl mainly feeds on small insects and occasionally on very small mammals and perhaps on the small chicks. Small insects made the major portion of the diet of Athene noctua.

Diet and food ontogeny of the lizard Tupinambis matipu Silva et al. 2018 (Squamata: Teiidae) in Central Brazil

The tegus are generalists lizards that use large amounts of prey in its diet, providing environmental services as a biological controller and seed disperser, which reveals how important diet studies are to understand ecological relationships related to a particular species. So the objective of this study was to analyze diet and food ontogeny of T. matipu, investigating changes in the pattern and composition of food items in different age classes and how the species shares its intraspecific niche. The captured specimens had the contents of their digestive tracts were analysed qualitatively and quantitatively. Our results indicate that T. matipu is a generalist lizard, consuming many food items, which fruits are the most important item in its diet. However, the species uses food resources in different importance proportions, according to its age class. Fruit consumption tends to increase and arthropods consumption decline as the age class increase. Thus, T. matipu performs an intraspecific sharing of feeding niche between the age classes and constitutes potential seed dispersers in its populations distributed along the Upper Course of the Paraguai River.

Congenital feeding response to a novel prey in a Mexican gartersnake

In this study, we explored chemosensory, ingestive and prey-catching responses of neonate Mexican Black-bellied Gartersnakes (Thamnophis melanogaster) to crayfish (Cambarellus montezumae). By comparing snakes from a recently discovered crayfish-eating population and a typical non-crayfish-eating population, we asked which behavioral components change as a species enlarges its feeding niche. In the crayfish-eating population chemosensory responsiveness to crayfish was not enhanced but its heritability was higher. Neonates of both populations showed similar preference for freshly-molted versus unmolted crayfish, and whereas the tendency to ingest both crayfish stages remained stable between ages 15 and 90 days in the non-crayfish-eating population, in the crayfish-eating population it actually decreased. Techniques to catch and manipulate molted crayfish were similar in the two populations. We discuss the possibility that there is no increase in the behavioral response to eat crayfish by the neonates of the crayfish-eating populations, possibly due to the absence of ecological and spatial isolation between the two T. melanogaster populations. The crayfish ingestion in some population of T. melanogaster can be explained by environmental differences between populations, or by recent origin of crayfish ingestion in T. melanogaster.

Feeding ecology of early life stages of striped bass (Morone saxatilis) along an estuarine salinity-turbidity gradient, St. Lawrence Estuary, Canada

After being extirpated from the St. Lawrence River in the 1960s, striped bass (Morone saxatilis) were reintroduced to the estuary in 2002 and by 2008, they were naturally reproducing. To document the habitat use and feeding ecology of this reintroduced population, we examined the gut contents of 333 larvae and juveniles. Samples were collected in four estuarine habitats in 2014: the upstream freshwater section (UP), the oligohaline (O-ETM) and the mesohaline (M-ETM) estuarine turbidity maximum zones, and the downstream polyhaline section (DOWN). In June, pelagic larvae developed in the UP and the O-ETM, feeding mainly on copepods such as Eurytemora affinis. The O-ETM exhibited better suitable feeding conditions compared to the UP, likely due to the presence of Bosmina sp. as a primary prey. After July, striped bass shifted to larger prey items, consuming mainly dipteran pupa in upstream littoral habitats and gammarids and mysids in downstream habitats. In the early summer, the UP provided a high-quality nursery habitat and as the season progressed, the smallest juveniles dispersed downstream and improved their feeding success by exploiting a new feeding niche. This observation suggests that being distributed throughout the estuary may increase the potential survival of striped bass early life stages.

Fundamental and realized feeding niche breadths of sexual and asexual stick insects

The factors contributing to the maintenance of sex over asexuality in natural populations remain unclear. Ecological divergences between sexual and asexual lineages could help to maintain reproductive polymorphisms, at least transiently, but the consequences of asexuality for the evolution of ecological niches are unknown. Here, we investigated how niche breadths change in transitions from sexual reproduction to asexuality. We used host plant ranges as a proxy to compare the realized feeding niche breadths of five independently derived asexual Timema stick insect species and their sexual relatives at both the species and population levels. Asexual species had systematically narrower realized niches than sexual species, though this pattern was not apparent at the population level. To investigate how the narrower realized niches of asexual species arise, we performed feeding experiments to estimate fundamental niche breadths but found no systematic differences between reproductive modes. The narrow realized niches found in asexual species are therefore probably a consequence of biotic interactions such as predation or competition, that constrain realized niche size in asexuals more strongly than in sexuals.