Context-specific behavior serves as a mechanism of interspecific cohesion in mixed-species flocks

We investigated whether context-specific behavior is responsible for the cohesion of mixed-species flocks of antshrikes and antwrens in Amazonian Peru. Antshrikes perform a behavior while spatially repositioning, to which antwrens respond by approaching. The cohesion of interspecific associations requires communication, although the mechanisms often are unexplored. In monospecific groups, cohesion among individuals is maintained with actions or vocalizations given in a certain context. Dusky-throated Antshrikes (Thamnomanes ardesiacus) vocalize while in flight and the number of times they vocalize covaries with the flight distance. We refer to this pairing of flight and vocalization as repositioning behavior. Furthermore, antshrikes pair a different call type with perching, which we refer to as perching behavior. We followed Long-winged (Myrmotherula longipennis) and White-flanked Antwrens (M. axillaris) and recorded their response following natural vocalizations (no playback used) given by the antshrikes. Long-winged Antwrens, but not White-flanked, flew toward an antshrike significantly sooner and were more likely to approach the antshrikes after the repositioning behavior than after perching behavior. In addition, Long-winged Antwrens, but not White-flanked, flew toward an antshrike sooner after a longer series of repositioning calls than after a shorter series. We did not distinguish between the Long-winged Antwrens’ response as a function of movement vs. vocalizations of the antshrikes, although we argue that vocalizations are likely a more important communication component of repositioning behavior than movement. It remains unclear whether the antshrikes are deliberately signaling the Long-winged Antwrens or the antwrens are taking advantage of the repositioning behavior; active signaling is possible since antshrikes benefit from antwrens. White-flanked Antwrens may be less responsive to the antshrikes since they have a lower propensity to occur in a mixed-species flock. The results indicate that the repositioning behavior of Dusky-throated Antshrikes is a key mechanism of interspecific cohesion of Amazonian mixed-species flocks of the understory.

No Evidence of Competition Between the Blacklegged Tick (Acari: Ixodidae) and American Dog Tick on the Rodent Host White-Footed Deermouse (Rodentia: Cricetidae) in Southwestern Tennessee

Investigations that analyze interspecific associations of vectors on their hosts are important for understanding community structure and implementing ways to comprehend mechanisms of pathogen transmission. We assessed the interspecific association of two tick species (Ixodes scapularis Say (Ixodida: Ixodidae) and Dermacentor variabilis Say (Ixodida: Ixodidae)) on the rodent host Peromyscus leucopus Rafinesque (Rodentia: Cricetidae) at the Hobart Ames Research and Education Center in southwestern Tennessee. Of the rodents captured, 95 (63%) had neither species of tick, 6 (4%) had both tick species, 25 (16%) had I. scapularis only, and 26 (17%) had D. variabilis only. A coefficient of association (C7 = −0.08) was calculated, which suggested there was competition between the two species of ectoparasites, but this value was not significant, indicating that there was a neutral relationship between the tick species on P. leucopus. The co-occurrence of both tick species on their host at the same time suggested that the two tick species can occupy the same host and use the same resources without competing.

Association Analysis among Fungi Colonizing Wheat Crop Residues During Decomposition for Sustainable and Environment-Friendly Management of Renewable Natural Resources

The interspecific associations between selected fungal species were calculated based on assumption; the species occurring together in Petri dishes during isolation from litter might be associated as well. Each Petridis was considered as a quadrate for association analysis. The presence and absence of different species in Petri dishes at different sampling dates were recorded as done in grasslands by the quadrate method. In the present study, the interspecific association between 16 fungal species was evaluated, which was isolated during the decomposition of above-ground residues of wheat crop. A sum of 136 combinations was analyzed. The chi-square (χ2) values were calculated to assess the significance of association (positive or negative), and the coefficient of association (V) was also enumerated to find out the extent of association between species in nature. Any organism was influenced by abiotic and biotic factors constituting its environment. The fungi are no exception; the colonization of a substrate by a fungus and its survival and multiplication depends upon the environment it gets. Therefore, before using any fungus as a bioinoculant, we must make sure that other microbes, especially the fungi already present on the substrate, do not negatively impact it. An analysis of the association between species colonizing the substrate would help determine the bioinoculant to be used for the degradation of organic waste in the interest of the environment to make it safe for everyone.

Environmental gradients and host availability affecting the symbiosis between Pteroclava krempfi and alcyonaceans in the Saudi Arabian central Red Sea

Interspecific associations are common in coral reefs, but those involving hydrozoans and octocorals have not been widely investigated. The hydroid Pteroclava krempfi (Hydrozoa, Cladocorynidae) lives in association with different soft coral taxa (Alcyonacea), showing a widespread distribution. However, very little information is available on the ecology of these relationships. Here, we tested for differences in the taxon-specific prevalence and habitat preference of the symbiosis and determined ecological traits of the P. krempfi-host associations in central Red Sea reefs. P. krempfi was found associated with the alcyonacean genera Lobophytum, Rhytisma, Sarcophyton and Sinularia, updating its host range and geographic distribution. The symbiosis prevalence was high in the area and especially at inshore sites compared to midshore and offshore sites. Rhytisma was the most common host, while the association with Lobophytum showed the lowest taxon-specific prevalence. P. krempfi did not show a clear preference for a specific alcyonacean size, and an increase in host size automatically led to an increase in the surface occupied by hydrozoans, although they rarely colonized more than 50% of the upper surface of the host. The spatial distribution of the hydroids on the host surface appeared related to the host genus and size as well as to the coverage of the hydroids. Despite the nature of this symbiosis requiring further investigation, P. krempfi did not seem to play a role in affecting the bleaching susceptibilities of the host colonies. The study shows that the Red Sea coral reef symbioses are more widespread than previously known and therefore deserve more attention.

Divergent Hydraulic Strategies Explain the Interspecific Associations of Co-Occurring Trees in Forest–Steppe Ecotone

Research Highlights: Answering how tree hydraulic strategies explain the interspecific associations of co-occurring trees in forest–steppe ecotone is an approach to link plant physiology to forest dynamics, and is helpful to predict forest composition and function changes with climate change. Background and Objectives: The forest–steppe ecotone—the driest edges of forest distribution—is continuously threatened by climate change. To predict the forest dynamics here, it is crucial to document the interspecific associations among existing trees and their potential physiological drivers. Materials and Methods: Forest–steppe ecotone is composed of forest and grassland patches in a mosaic pattern. We executed two years of complete quadrat surveys in a permanent forest plot in the ecotone in northern China, calculated the interspecific association among five main tree species and analyzed their hydraulic strategies, which are presented by combining leaf-specific hydraulic conductivity (Kl) and important thresholds on the stem-vulnerability curves. Results: No intensive competition was suggested among the co-occurring species, which can be explained by their divergent hydraulic strategies. The negative associations among Populus davidiana Dode and Betula platyphylla Suk., and P. davidiana and Betula dahurica Pall. can be explained as the result of their similar hydraulic strategies. Tilia mongolica Maxim. got a strong population development with its effective and safe hydraulic strategy. Generally, hydraulic-strategy differences can explain about 40% variations in interspecific association of species pairs. Oppositely, species sensitivity to early stages of drought is convergent in the forest. Conclusions: The divergent hydraulic strategies can partly explain the interspecific associations among tree species in forest–steppe ecotone and may be an important key for semiarid forests to keep stable. The convergent sensitivity to early stages of drought and the suckering regeneration strategy are also important for trees to survival. Our work revealing the physiological mechanism of forest compositions is a timely supplement to forest–steppe ecotone vegetation prediction.

A new report on mixed species association between Nilgiri Langurs Semnopithecus johnii and Tufted Grey Langurs S. priam (Primates: Cercopithecidae) in the Nilgiri Biosphere Reserve, Western Ghats, India

Phylogenetic conservatism or rapid anthropogenic habitat modifications could increase the incidences of interspecific associations of Hanuman and Nilgiri langurs (Family: Cercopithecidae, subfamily: Colobinae) in the southern Western Ghats. Opportunistic surveys were conducted at the Silent Valley National Park, Kerala and around Devimalai Ghats, Tamil Nadu for Tufted Grey-Nilgiri Langur association. Based on the observations from Researchers, field assistants, forest staff, and local people, the data in terms of the time of the sighting, number of individuals, phenotypes of individuals, and the time the interaction lasted, were recorded. The study reports data on a troop of Nilgiri Langurs (N=13) around O Valley tea estate at Devimalai Ghat, Gudalur, Tamil Nadu with some hybrid looking individuals and a Tufted female Grey Langur amongst them. A total of six and two uni-male troops of Nilgiri Langurs and grey langurs respectively with Tufted female Grey Langurs, and aberrant coat colored infants observed at the Neelikkal section of Silent Valley National Park are also reported. The study reasonably speculates that there could be more such locations in the southern western ghats and emphasizes the need for more systematic surveys to understand and explore the ecology, behavior, molecular, and other likely factors contributing to the conservation of vulnerable Nilgiri langur (Semnopithecus johnii) populations.