Seroprevalence of Leprosy in Nine-Banded Armadillos (Dasypus novemcinctus) from Tennessee, USA, 2021-22.

The nine-banded armadillo (Dasypus novemcinctus) is currently considered an invasive species in parts of its range in the USA, and this range continues to expand to the north and east. Nine-banded armadillos are one of a handful of mammals known to contract leprosy (also known as Hansen's disease); range expansion thus leads to public health concerns about whether this might increase human exposure to infected animals. We collected blood samples from 61 road-killed armadillos over two summers (2021 and 2022) in Tennessee, a US state near the northern extreme of the species' current range, and screened them for exposure to Mycobacterium leprae, the causative agent of leprosy. All animals were seronegative, providing no evidence that range expansion is increasing the distribution of leprosy in the US.

Growing as slow as a turtle: Unexpected maturational differences in a small, long-lived species.

Turtle body size is associated with demographic and other traits like mating success, reproductive output, maturity, and survival. As such, growth analyses are valuable for testing life history theory, demographic modeling, and conservation planning. Two important but unsettled research areas relate to growth after maturity and growth rate variation. If individuals exhibit indeterminate growth after maturity, older adults may have an advantage in fecundity, survival, or both over younger/smaller adults. Similarly, depending on how growth varies, a portion of the population may mature earlier, grow larger, or both. We used 23-years of capture-mark-recapture data to study growth and maturity in the Spotted Turtle (Clemmys guttata), a species suffering severe population declines and for which demographic data are needed for development of effective conservation and management strategies. There was strong support for models incorporating sex as a factor, with the interval growth model reparametrized for capture-mark-recapture data producing later mean maturation estimates than the age-based growth model. We found most individuals (94%) continued growing after maturity, but the instantaneous relative annual plastral growth rate was low. We recommend future studies examine the possible contribution of such slow, continued adult growth to fecundity and survival. Even seemingly negligible amounts of annual adult growth can have demographic consequences affecting the population vital rates for long-lived species.

Concentrations of persistent organic pollutants in plasma from two species of turtle from the Tennessee River Gorge.

Persistent organic pollutants (POPs) are characterized by their resistance to degradation, biomagnification, global transport, and adverse toxicological effects. The goal of this study was to determine baseline concentrations of several classes of POPs, including polychlorinated biphenyls (PCBs), organochlorine pesticides, and polybrominated diphenyl ethers (PBDEs) in two turtle species, the Cumberland slider (Trachemys scripta troosti) and the common musk turtle (Sternotherus odoratus) from the Tennessee River Gorge. Plasma samples from five male and five female adults of each species were analyzed for concentrations of 83 PCB congeners, six DDT compounds, four toxaphene congeners, 18 additional pesticides, pentachlorobenzene, octachlorostyrene, and 28 PBDE congeners using gas chromatography/mass spectrometry. In both species, total PCBs were the predominant contaminant class, at approximately 10-fold higher concentration than p,p'-DDE, total PBDEs, and total chlordanes. Mirex, dieldrin and one toxaphene congener (Parlar 50) were also detected at even lower concentrations. The female turtles had lower concentrations of some contaminants (PCB 153+132, oxychlordane, mirex, PBDE 153, PBDE 154, Sigma PBDEs) than males, suggesting maternal transfer to eggs. Cumberland sliders had lower concentrations of PCB 138, p,p'-DDE, Sigma DDTs, oxychlordane, PBDE 47, and PBDE 99 than musk turtles. The turtles had a unique PBDE pattern with PBDE 100 predominating. The POP concentrations were lower than those measured previously in other reptiles from contaminated sites where endocrine disruption has been observed. One exception was a female musk turtle with 29.9 ng g(-1) p,p'-DDE (wet mass basis), which is greater than the concentrations measured in reptiles with evidence of endocrine disruption. Additional monitoring and research is necessary to determine if other species or age classes in this turtle assemblage might be at higher risk of POP accumulation, as well as to assess the potential risk of these concentrations on their health and reproduction.

An oscillator model of the timing of turn-taking.

When humans talk without conventionalized arrangements, they engage in conversation--that is, a continuous and largely nonsimultaneous exchange in which speakers take turns. Turn-taking is ubiquitous in conversation and is the normal case against which alternatives, such as interruptions, are treated as violations that warrant repair. Furthermore, turn-taking involves highly coordinated timing, including a cyclic rise and fall in the probability of initiating speech during brief silences, and involves the notable rarity, especially in two-party conversations, of two speakers' breaking a silence at once. These phenomena, reported by conversation analysts, have been neglected by cognitive psychologists, and to date there has been no adequate cognitive explanation. Here, we propose that, during conversation, endogenous oscillators in the brains of the speaker and the listeners become mutually entrained, on the basis of the speaker's rate of syllable production. This entrained cyclic pattern governs the potential for initiating speech at any given instant for the speaker and also for the listeners (as potential next speakers). Furthermore, the readiness functions of the listeners are counterphased with that of the speaker, minimizing the likelihood of simultaneous starts by a listener and the previous speaker. This mutual entrainment continues for a brief period when the speech stream ceases, accounting for the cyclic property of silences. This model not only captures the timing phenomena observed inthe literature on conversation analysis, but also converges with findings from the literatures on phoneme timing, syllable organization, and interpersonal coordination.