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Kellner, K.

Publications and source records attributed to Kellner, K..

5 recordsLinked to original sources

Private forest reserves in Brazils agricultural landscapes effectively sustain the occupancy and abundance of multiple threatened large vertebrate

1. Understanding the factors that shape wildlife abundance and distributions is at the core of applied ecology and wildlife management. Accurate predictions on the population level outcomes of land management are especially urgent in biodiversity hotspots around the world that are undergoing rapid transformation. In South America, both the Cerrado and Amazon are increasingly being converted to agricultural land-uses to produce soybean and corn and raise cattle. Over the last several decades Brazil has become one of the leading global producers of these products. At the same time, Brazil has some of the strongest federal regulations focused on protecting native habitat. The Native Vegetation Protection Law (or the Forest Code) requires private properties retain native vegetation as Legal Reserves, and as a result more than half of the countrys remaining native habitat now lies on private lands. Whether retained habitat under this ambitious policy sustains populations of large, wide-ranging vertebrates across entire agricultural production landscapes remains untested. 2. Here, we conducted a landscape scale survey using camera-trap stations across ~606,000 km2 of Mato Grosso, Brazils largest producer of cattle, soybean and corn. We sampled 115 independent sites between November 2024 and September 2025, spanning both crop seasons. We estimated occupancy of jaguars and expected abundance of white-lipped peccary and lowland tapir, using a combination of occupancy and Royle Nichols models. We fit an abundance-mediated interaction model to formally test the role of prey abundance in driving jaguar occupancy across the landscape. 3. We found high occurrence and expected abundance of all three species. Forest cover was the only covariate common to all top models for every species: predicted jaguar occupancy probability rose as forest cover increased and expected peccary and tapir abundance also increased as a function of forest cover. 4. Our empirical estimates from abundance-mediated interaction models were consistent with jaguar occupancy being a function of both habitat availability and prey (peccary) abundance. 5. Synthesis and applications. Native forest retained on private land under Brazil's Forest Code is associated with the persistence and local abundance of an apex predator, a megaherbivore and a keystone ungulate across one of the world's most intensively farmed regions. Jaguar occupancy rose from 0.33 to 0.87 as forest cover increased from 15% to 65%, indicating that maintaining Legal Reserve requirements is central to retaining large vertebrates in production landscapes. Private reserves should be managed as complements to, not substitutes for, protected areas and Indigenous territories, and habitat-retention policy should be paired with mitigation of crop damage and livestock depredation to prevent retained forests from becoming ecological traps. Our framework provides a transferable approach for evaluating habitat-retention policies for wide-ranging species elsewhere.

ecology↗

Phylosymbiosis and the hologenome in fungus-gardening ants

Hosts and their microbiomes can be extensively integrated so that they behave across evolutionary scales as a single unit or as a hologenome. Hosts and their associated microbiomes can potentially exhibit concordance among their respective phylogenetic histories, a phenomenon known as phylosymbiosis. The obligate symbiosis of fungus-gardening ants represents a complex symbiotic system as there are two macroscopic hosts that have associated microbiomes. Here we apply 16S rRNA gene analysis of microbiomes in combination with phylogenetic analysis of nuclear genes and SNPs (single nucleotide polymomorphisms) of hosts to determine the extent to which phylosymbiosis characterizes the coevolution among ant hosts, fungal symbionts and bacterial microbiomes of five species of fungus-gardening ants. The strongest evidence of phylosymbiosis (i.e., congruent topologies between host phylogenetics and microbiome structure) was found between ants and ant-associated microbiomes. While fungal phylogenies and microbiome dendrograms were correlated, these correlations were not topologically congruent. We conclude that phylosymbiosis is present between the ant hosts and their ant-associated microbiome and this would be the strongest evidence of the hologenome concept within the attine symbiosis.

evolutionary biology↗

Atta Leafcutter Ants are Fine-Scale Bioindicators of Geographic and Seasonal Climate Changes Across the Americas

AimWe develop Atta leafcutter-ants as bioindicators that respond at fine scales to geographic and seasonal climate changes in the Americas, thereby addressing the paucity of versatile insect bioindicator systems capable of monitoring climate in both Southern and Northern Hemispheres. LocationAmerican tropics and sub-tropics from latitudes S33.6{degrees} to N33.2{degrees}, with case studies from Colombia, Mexico, and southern USA. Time Period2012-2024. Taxon StudiedAtta leafcutter-ants. MethodsWe elucidate biogeographic patterns of mating-flight phenology of Atta leafcutter-ants across the entire Atta range from Uruguay/Argentina to the USA, using 2335 records of Atta reproductives from the community database iNaturalist, then ground-truth these patterns by comparison with (i) mating-flight records (n=806) from the Atta literature; and (ii) mating-flight observations (n=836) accumulated by a consortium of experts who have researched Atta for a combined 1000+ work-years. Onset of mating flights can be timed with great precision in Atta populations because mass-mating flights are synchronized and triggered by the first major rainfall of a rainy season. ResultsBiogeographic patterns in climate-dependent mating-flight phenologies recorded at iNaturalist are corroborated by observations accumulated in the literature and by Atta experts. Analyses reveal so-far unknown gradients in mating-flight phenology (e.g., Colombia to USA) that are correlated to geographic climate gradients, and season switches of mating flights from early to late in the year between proximate Atta populations (e.g., 200 kilometers apart), for example in the climatically complex Andean regions of Colombia. Regional differences in Atta mating-flight phenology correspond to temporal differences in rainfall between ecoregions of Colombia. Main ConclusionsAtta ants are tractable insect bioindicators to monitor climate impacts with detailed spatial and temporal resolution across a 9200-kilometer trans-equatorial transect in the Americas. We outline future research directions to explore climate-dependent biology using the continuously growing, and now ground-truthed, information at iNaturalist on Atta mating behavior.

ecology↗

When does temporal resolution matter? Including detection covariates in discrete- versus continuous-time occupancy and N-mixture models

Camera traps and other sensors allow continuous-time biodiversity observation, raising new questions and opportunities for modelling detection in hierarchical models such as occupancy (for species presence) and N-mixture models (for abundance). We focused on a rarely considered aspect: how the temporal treatment of detection covariates affects inference. Through simulations and a five-month case study on an research center, we examined the effects of covariate temporal resolution, discretisation scale in discrete-time (DT) models, and interpolation methods in continuous-time (CT) models. While occupancy and abundance estimates were largely unaffected by these choices, detection estimates were more sensitive to them. DT models with fine temporal discretisation closely matched CT models. Simulations showed that when detection covariates had no effect on detectability, the considered modelling choices had little impact. But when covariates did influence detection, bias and error increased if their temporal variation was not accurately retained. The case study revealed more complex patterns, highlighting the consequences of temporally simplifying both observations and detection covariates. Overall, our results suggest that when detectability is of ecological interest, exploring a range of temporal treatments of detection covariates, from fine-scale to coarser resolutions, can reveal complementary insights into scale-dependent patterns in detection.

ecology↗

Landscape genomics of an obligate mutualism: discordant population structures between a leafcutter-ant and its fungal cultivars

To explore landscape genomics at the range limit of an obligate mutualism, we used genotyping-by-sequencing (ddRADseq) to quantify population structure and the effect of hostsymbiont interactions between the northernmost fungus-farming leafcutter ant Atta texana and its two main types of cultivated fungus. At local scales, genome-wide differentiation between ants associated with either of the two fungal types is greater than the differentiation associated with the abiotic factors temperature and precipitation, suggesting that specific ant-fungus genome-genome combinations may have been favored by selection. For the ant hosts, we found a broad cline of genetic structure across the range, and a reduction of genetic diversity along the axis of range expansion towards the range margin. In contrast, genetic structure was patchy in the cultivated fungi, with no consistent reduction of fungal genetic diversity at the range margins. This discordance in population-genetic structure between ant hosts and fungal symbionts is surprising because the ant farmers co-disperse with their vertically-transmitted fungal symbionts, but apparently the fungi disperse occasionally also through between-nest horizontal transfer or other unknown dispersal mechanisms. The discordance in populationgenetic structure indicates that genetic drift and gene flow differ in magnitude between each partner in this leafcutter mutualism. Together, these findings imply that variation in the strength of drift and gene flow experienced by each mutualistic partner affects adaptation to environmental stress at the range margin, and genome-genome interactions between host and symbiont influences adaptive genetic differentiation of the host during range evolution in this obligate mutualism.

evolutionary biology↗