Diverse aging rates in ectothermic tetrapods provide insights for the evolution of aging and longevity

Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher diversity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.Animal science

Life history, population viability, and the potential for local adaptation in isolated trout populations

Habitat loss and fragmentation have caused population decline across taxa through impacts on life history diversity, dispersal patterns, and gene flow. Yet, intentional isolation of native fish populations is a frequently used management strategy to protect against negative interactions with invasive fish species. We evaluated the population viability and genetic diversity of 12 isolated populations of Oncorhynchus clarkii lewisi located on the Flathead Indian Reservation in Montana, USA. Length-structured integral projection models (IPMs) were used to project population growth rate (lambda) and its sensitivity to underlying vital rates and parameters. We examined relationships between lambda, genetic diversity, and habitat size and quality. Lambda ranged from 0.68 to 1.1 with 10 of 12 populations projected to be in decline. A sensitivity analysis of lambda with respect to projection matrix elements indicated that lambda was generally sensitive to changes in early life history stages (survival/growth), but patterns differed among populations. Another sensitivity analysis with respect to underlying model parameters showed highly consistent pattern across populations, with lambda being most sensitive to the slope of probability of maturity (estimated from published literature), generally followed by adult survival, and the slope of somatic growth rate (directly measured from each population). Lambda was not correlated with genetic diversity. For populations residing in small isolated streams (≤5 km of occupied habitat), lambda significantly increased with base flow discharge (r2=0.50, p<0.02). Our results highlight the potential importance of local adaptation for persistence of small, isolated populations. Specifically we saw evidence for higher probability of maturity at smaller sizes in the smallest, coldest isolated systems, increasing probability of persistence for these populations. Climate change threatens to further fragment populations of aquatic organisms and reduce summertime base flows in much of western North America. Insights from studies such as ours will inform management strategies for long-term persistence of species facing these challenges

Black hole formation from axion stars

The classical equations of motion for an axion with potential V(phgr)=ma2fa2 [1−cos (phgr/fa)] possess quasi-stable, localized, oscillating solutions, which we refer to as ``axion stars''. We study, for the first time, collapse of axion stars numerically using the full non-linear Einstein equations of general relativity and the full non-perturbative cosine potential. We map regions on an ``axion star stability diagram", parameterized by the initial ADM mass, MADM, and axion decay constant, fa. We identify three regions of the parameter space: i) long-lived oscillating axion star solutions, with a base frequency, ma, modulated by self-interactions, ii) collapse to a BH and iii) complete dispersal due to gravitational cooling and interactions. We locate the boundaries of these three regions and an approximate ``triple point" (MTP,fTP) ~ (2.4 Mpl2/ma,0.3 Mpl). For fa below the triple point BH formation proceeds during winding (in the complex U(1) picture) of the axion field near the dispersal phase. This could prevent astrophysical BH formation from axion stars with fa Lt Mpl. For larger fa gsim fTP, BH formation occurs through the stable branch and we estimate the mass ratio of the BH to the stable state at the phase boundary to be Script O(1) within numerical uncertainty. We discuss the observational relevance of our findings for axion stars as BH seeds, which are supermassive in the case of ultralight axions. For the QCD axion, the typical BH mass formed from axion star collapse is MBH ~ 3.4 (fa/0.6 Mpl)1.2 M⊙