Tooth damage in carnivores can reflect shifts in both diet and feeding habits, and in large carnivores, it is associated with increased bone consumption. Variation in tooth condition in Icelandic ...arctic foxes, a mesocarnivore, was recorded from 854 individual foxes spanning 29 years. We hypothesized that annual climatic variations, which can influence food abundance and accessibility, will influence tooth condition by causing dietary shifts toward less edible prey. We examined tooth condition in relation to four climatic predictors: mean annual winter temperature, indices of both the El Niño anomaly and North Atlantic subpolar gyre (SPG), and the number of rain‐on‐snow days (ROS). We found unequivocal evidence for a strong effect of annual climate on tooth condition. Teeth of Icelandic foxes were in better condition when winter temperatures were higher, when the SPG was more positive, and when the number of ROS was low. We also found a substantial subregional effect with foxes from northeastern Iceland having lower tooth damage than those from two western sites. Contradicting our original hypothesis that foxes from northeastern Iceland, where foxes are known to scavenge on large mammal remains (e.g., sheep and horses), would show the highest tooth damage, we suggest that western coastal sites exhibited greater tooth damage because cold winter temperatures lowered the availability of seabirds, causing a shift in diet toward abrasive marine subsidies (e.g., bivalves) and frozen beach wrack. Our study shows that monitoring tooth breakage and wear can be a useful tool for evaluating the impact of climate on carnivore populations and that climate change may influence the condition and fitness of carnivores in complex and potentially conflicting ways.
Tooth damage in carnivores can reflect shifts in both diet and feeding habits. We examined tooth condition in 854 Icelandic arctic foxes collected over 29 years from three regions. We hypothesized that annual climatic variations would cause dietary shifts toward less edible prey. We found unequivocal evidence for a strong effect of annual climate. Teeth of Icelandic foxes were less damaged when winter temperatures were higher, when the North Atlantic subpolar gyre was more positive, and when the number of rain‐on‐snow days was low. Shifts in diet toward abrasive marine subsidies (e.g., bivalves) and frozen beach wrack worsened tooth condition.
Many of the world's vertebrates have experienced large population and geographic range declines due to anthropogenic threats that put them at risk of extinction. The largest vertebrates, defined as ...megafauna, are especially vulnerable. We analyzed how human activities are impacting the conservation status of megafauna within six classes: mammals, ray‐finned fish, cartilaginous fish, amphibians, birds, and reptiles. We identified a total of 362 extant megafauna species. We found that 70% of megafauna species with sufficient information are decreasing and 59% are threatened with extinction. Surprisingly, direct harvesting of megafauna for human consumption of meat or body parts is the largest individual threat to each of the classes examined, and a threat for 98% (159/162) of threatened species with threat data available. Therefore, minimizing the direct killing of the world's largest vertebrates is a priority conservation strategy that might save many of these iconic species and the functions and services they provide.
Large mammalian carnivores are ecologically important because relatively few individuals can cause strong predation-driven direct effects or fear-driven indirect effects that can ripple through ...communities and, ultimately, influence ecosystem structure and function. Most mammalian carnivores are not large, however, but are small to midsized species collectively termed “mesocarnivores.” Mesocarnivores are more numerous and more diverse than larger carnivores, and often reside in closer proximity to humans, yet we know little about how they influence communities and ecosystems. In this article we review the ecological role of the mesocarnivore and present examples where mesocarnivores drive community structure and function in roles similar to, or altogether different from, their larger brethren. Together, these examples substantiate the need for an assessment of the ecological role of mammalian carnivores beyond an examination of only the largest species. In particular, we emphasize the need to study the trophic penetrance of mesocarnivores and examine how ecological context modulates their functional role.
There is a growing realization that traditional “Calculus for Life Sciences” courses do not show their applicability to the Life Sciences and discourage student interest. There have been calls from ...the AAAS, the Howard Hughes Medical Institute, the NSF, and the American Association of Medical Colleges for a new kind of math course for biology students, that would focus on dynamics and modeling, to understand positive and negative feedback relations, in the context of important biological applications, not incidental “examples.” We designed a new course, LS 30, based on the idea of modeling biological relations as dynamical systems, and then visualizing the dynamical system as a vector field, assigning “change vectors” to every point in a state space. The resulting course, now being given to approximately 1400 students/year at UCLA, has greatly improved student perceptions toward math in biology, reduced minority performance gaps, and increased students' subsequent grades in physics and chemistry courses. This new course can be customized easily for a broad range of institutions. All course materials, including lecture plans, labs, homeworks and exams, are available from the authors; supporting videos are posted online.
The evolution of mammalian olfaction is manifested in a remarkable diversity of gene repertoires, neuroanatomy and skull morphology across living species. Olfactory receptor genes (ORGs), which ...initiate the conversion of odorant molecules into odour perceptions and help an animal resolve the olfactory world, range in number from a mere handful to several thousand genes across species. Within the snout, each of these ORGs is exclusively expressed by a discrete population of olfactory sensory neurons (OSNs), suggesting that newly evolved ORGs may be coupled with new OSN populations in the nasal epithelium. Because OSN axon bundles leave high-fidelity perforations (foramina) in the bone as they traverse the cribriform plate (CP) to reach the brain, we predicted that taxa with larger ORG repertoires would have proportionately expanded footprints in the CP foramina. Previous work found a correlation between ORG number and absolute CP size that disappeared after accounting for body size. Using updated, digital measurement data from high-resolution CT scans and re-examining the relationship between CP and body size, we report a striking linear correlation between relative CP area and number of functional ORGs across species from all mammalian superorders. This correlation suggests strong developmental links in the olfactory pathway between genes, neurons and skull morphology. Furthermore, because ORG number is linked to olfactory discriminatory function, this correlation supports relative CP size as a viable metric for inferring olfactory capacity across modern and extinct species. By quantifying CP area from a fossil sabertooth cat (Smilodon fatalis), we predicted a likely ORG repertoire for this extinct felid.
Over the past 50 million years, successive clades of large carnivorous mammals diversified and then declined to extinction. In most instances, the cause of the decline remains a puzzle. Here we argue ...that energetic constraints and pervasive selection for larger size (Cope's rule) in carnivores lead to dietary specialization (hypercarnivory) and increased vulnerability to extinction. In two major clades of extinct North American canids, the evolution of large size was associated with a dietary shift to hypercarnivory and a decline in species durations. Thus, selection for attributes that promoted individual success resulted in progressive evolutionary failure of their clades.
The golden jackal of Africa (Canis aureus) has long been considered a conspecific of jackals distributed throughout Eurasia, with the nearest source populations in the Middle East. However, two ...recent reports found that mitochondrial haplotypes of some African golden jackals aligned more closely to gray wolves (Canis lupus) 1, 2, which is surprising given the absence of gray wolves in Africa and the phenotypic divergence between the two species. Moreover, these results imply the existence of a previously unrecognized phylogenetically distinct species despite a long history of taxonomic work on African canids. To test the distinct-species hypothesis and understand the evolutionary history that would account for this puzzling result, we analyzed extensive genomic data including mitochondrial genome sequences, sequences from 20 autosomal loci (17 introns and 3 exon segments), microsatellite loci, X- and Y-linked zinc-finger protein gene (ZFX and ZFY) sequences, and whole-genome nuclear sequences in African and Eurasian golden jackals and gray wolves. Our results provide consistent and robust evidence that populations of golden jackals from Africa and Eurasia represent distinct monophyletic lineages separated for more than one million years, sufficient to merit formal recognition as different species: C. anthus (African golden wolf) and C. aureus (Eurasian golden jackal). Using morphologic data, we demonstrate a striking morphologic similarity between East African and Eurasian golden jackals, suggesting parallelism, which may have misled taxonomists and likely reflects uniquely intense interspecific competition in the East African carnivore guild. Our study shows how ecology can confound taxonomy if interspecific competition constrains size diversification.
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•African and Eurasian golden jackals are genetically distinct lineages•Divergence between lineages is concordant across multiple molecular markers•Morphologic convergence is observed between African and Eurasian golden jackals•African golden jackals merit recognition as a distinct species
Koepfli et al. assess divergence between golden jackals (Canis aureus) from Africa and Eurasia using data from the mitochondrial and nuclear genomes. They show that African and Eurasian golden jackals are genetically distinct and independent lineages, and that African golden jackals likely represent a separate species.
Tour of a Labyrinth: Exploring the Vertebrate Nose Valkenburgh, Blaire; Smith, Timothy D.; Craven, Brent A.
Anatomical record (Hoboken, N.J. : 2007),
November 2014, Letnik:
297, Številka:
11
Journal Article
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