Biology subjects

Pignatelli, A.

Publications and source records attributed to Pignatelli, A..

3 recordsLinked to original sources

bioRxiv2024

Nonlinear thinking in ecology and evolution: The case for ecological scaling of the Threshold Elemental Ratio

Nonlinear dynamics govern ecological processes, thus understanding thresholds is important for measuring and forecasting effects of climate change and management of natural resources. However, identifying whether and how such thresholds scale across biological levels of organization remains challenging. Ecological stoichiometry, the study of the balance of multiple elements and energy in ecological systems, provides a framework for scaling thresholds. We broaden a key organismal concept from ecological stoichiometry theory, the Threshold Elemental Ratio (TER), to study how nonlinear dynamics operate in evolutionary and ecological processes across the organizational hierarchy. Traditionally, TERs are used to describe the elemental ratio at which the limitation of organismal growth shifts from one element to another. Following this definition, we make a case for broadening the ecological scale of the TER beyond organisms to include populations, clades, communities, and ecosystems. We show how TERs can be detected and translated across different scales of biological and evolutionary organization through simulation modeling, literature review, and synthesis of empirical examples from diverse systems and ecological scales including: cyanotoxin production in lakes, alder-salmon dynamics, and the Cambrian explosion. Collectively, we demonstrate that TERs are widespread and consequential across levels of biological organization and that such thresholds manifest from a diversity of mechanisms. Thus, scaling of the TER concept holds promise for advancing our understanding of nonlinear dynamics from the micro-evolutionary to macro-ecological.

ecology↗

bioRxiv2024

The use of vocal coordination in male African elephant group departures: evidence of active leadership and consensus

Group-living animals engage in coordinated vocalizations to depart from a location as a group, and often, to come to a consensus about the direction of movement. Here, we document for the first time, the use of coordinated vocalizations, the "lets go" rumble, in wild male African elephant group departures from a waterhole. We recorded vocalizations and collected behavioral data as known individuals engaged in these vocal bouts during June-July field seasons in 2005, 2007, 2011, and 2017 at Mushara waterhole within Etosha National Park, Namibia. During departure events, we documented which individuals were involved in the calls, the signature structure of each individuals calls, as well as the ordering of callers, the social status of the callers, and those who initiated departure. The "lets go" rumble was previously described in tight-knit family groups to keep the family together during coordinated departures. Male elephants are described as living in loose social groups, making this finding particularly striking. We found that this vocal coordination occurs in groups of closely associated, highly bonded individuals and rarely occurs between looser associates. The three individuals most likely to initiate the "lets go" rumble bouts were all highly socially integrated, and one of these individuals was also the most dominant overall. This suggests that more socially integrated individuals might be more likely to initiate, or lead, a close group of associates in the context of leaving the waterhole, just as a dominant female would do in a family group. The fact that many individuals were often involved in the vocal bouts, and that departure periods could be shorter, longer, or the same amount of time as pre-departure periods, all suggest that there is consensus with regard to the act of leaving, even though the event was triggered by a lead individual.

animal behavior and cognition↗

bioRxiv2024

Rules of departure: Antiphony and personalized vocal spaces in wild male elephant group coordination

In the intricate realm of animal communication, vocal signals play a vital role in maintaining bonds and coordinating group activities. Through detailed analysis of low-frequency rumble vocalizations of wild male African Savannah elephants, we demonstrate how these calls are employed in a coordinated manner. Our findings reveal a distinct pattern of call-and-response, usually initiated by a dominant male, with subsequent turn-taking responses from other group members. This antiphonal calling is instrumental in facilitating collective decision-making and group departures, highlighting a sophisticated level of communication previously unrecognized in male elephant groups. Furthermore, the study delves into the frequency content of these rumbles, finding significant individual variations in vocal characteristics. Analysis of the first two formant frequencies of these calls uncovers a distinct vocal space for each elephant, variable over time and across different social contexts. These individualized vocal spaces suggest a mechanism for personal identification within and across elephant groups, and may also relate to the information content of their vocal exchanges. The vocal spaces and structured antiphony presented in this study underline the complexity of elephant vocal communication and invite further targeted research into the vocal communication system of elephants, as well as inquiry into the cognitive and social aspects of wildlife communication in general.

animal behavior and cognition↗