Frontiers in Ecology and Evolution

Published by Frontiers

Online ISSN: 2296-701X

Articles


FIGURE 1 | (A) Map of Early Oldowan African sites: 1, Lomekwi; 2, Bokol Dora; 3, Gona; 4, Hadar (AL666); 5, Lokalalei; 6, Omo; 7, Ain Boucherit; 8, Kanjera South; 9, Koobi Fora; 10, Oldupai Gorge; 11, Fejej; 12, Melka Kunture; 13, Sterkfontein; 14, Ain Hanech; 15, El Kherba. (B) Detail map on Oldupai Gorge and the location of Ewass Oldupa in relation with DK, FLK, Loc. 68, Naibor Soit and Nasiusiu. (C) Stratigraphic section from Ewass Oldupa, subdivided into two segments: Lower Bed I (i) and Upper Bed I (ii). See Mercader et al. (2021) for detailed descriptions. Maps modified from Tinted Hillshade using ESRI ArcGIS Desktop 10.5.1 (https://desktop.arcgis.com) and Images ServicesWorldElevation/Terrain Server Tinted Hillside Airbus, USGS, NGA, NASA, CGIAR, NCEAS, NLS, OS, NMA, Geodatastyrelsen, GSA, GSI and the GIS user community (CC BY-SA 4.0; https://creativecommons.org/licenses/by/4.0/).
FIGURE 2 | Selection of stone tools from Phase I. (A) Quartzite multipolar multifacial core with technical schemes. (B) Quartzite bifacial orthogonal core with technical schemes. (C) Quartzite unifacial centripetal core with technical schemes. (D,E) Quartzite flakes. Red arrows indicate the directions of flake's removals. complete cortical surfaces (4.6%). Scars on dorsal surfaces range from 0 to 4 (X = 2.1), involving unipolar, bipolar, and centripetal extractions. There are 23 debris fragments. As in previous phases, fragmented flakes present lateral (19%), distal (47.6%), and longitudinal (33.3%) fractures. No retouched flakes were recovered in Phase IV. The number of cores is low, and each core represents a different knapping method: multipolar multifacial, unipolar longitudinal, bifacial orthogonal, bifacial centripetal, and bipolar on anvil. The core metrics and number of removals per knapping method are given in Supplementary Table 7. All cores were on quartzite. Four of them occurred on tabular clasts, except for one (bifacial orthogonal) on flake. Percussive implements are limited to one quartzite hammerstone, measuring 87.8 × 57.3 × 47.9 mm. The stone tool assemblage of Phase V was scattered within 9 m 2 . The artifacts are limited to 15 quartzite lithics. The artifacts present no signs of erosion. Complete flakes are dominant, with average dimensions and SDs of 32 ± 9.5 mm × 29.5 ± 8 mm × 12.5 ± 3 mm. Platform average dimensions and SDs are 17.2 ± 9.7 mm × 8.8 ± 4.1 mm. The platforms are mostly single-facetted, with two examples of cortical platforms and one of bi-facetted platform. The flakes have non-cortical dorsal surfaces almost exclusively, except for two cortical flakes. Dorsal surfaces record scars ranging from 1 to 7 scars (X = 2.4), involving unipolar and centripetal reduction.
FIGURE 3 | Selection of stone tools from Phase II. (A) Ignimbrite chopping tool with technical schemes. (B) Ignimbrite chopper with technical schemes. (C) Quartzite unipolar longitudinal core with technical schemes. (D) Quartzite multipolar multifacial core with technical schemes. (E) Quartzite unifacial centripetal core with technical schemes. (F,G) Quartzite flakes. (H) Basalt percussive material. Detail shows impact marks on the surface. Red arrows indicate the directions of flake's removals.
FIGURE 4 | Selection of stone tools from Phase III. (A) Quartzite bifacial orthogonal core with technical schemes. Detail shows impact marks on the surface. (B) Quartzite multipolar multifacial core with technical schemes. (C) Quartzite unifacial centripetal core with technical schemes. (D) Quartzite spheroid. (E-H) Quartzite flakes. Red arrows indicate the directions of flake's removals.
FIGURE 5 | Selection of stone tools from Phase IV. (A) Quartzite bifacial orthogonal core with technical schemes. (B) Quartzite multipolar multifacial core with technical schemes. (C-F) Quartzite flakes. (G) Quartzite unipolar longitudinal core with technical schemes. Red arrows indicate the directions of flake's removals.

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Oldowan Technology Amid Shifting Environments ∼2.03–1.83 Million Years Ago
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March 2022

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Julio Mercader
The Oldowan represents the earliest recurrent evidence of human material culture and one of the longest-lasting forms of technology. Its appearance across the African continent amid the Plio-Pleistocene profound ecological transformations, and posterior dispersal throughout the Old World is at the foundation of hominin technological dependence. However, uncertainties exist concerning the degree to which the Oldowan constitutes an environment-driven behavioral adaptation. Moreover, it is necessary to understand how Oldowan technology varied through time in response to hominin ecological demands. In this study, we present the stone tool assemblage from Ewass Oldupa, a recently discovered archeological site that signals the earliest hominin occupation of Oldupai Gorge (formerly Olduvai) ∼2.03 Ma. At Ewass Oldupa, hominins underwent marked environmental shifts over the course of a ∼200 kyr period. In this article, we deployed an analysis that combines technological and typological descriptions with an innovative quantitative approach, the Volumetric Reconstruction Method. Our results indicate that hominins overcame major ecological challenges while relying on technological strategies that remained essentially unchanged. This highlights the Oldowan efficiency, as its basic set of technological traits was able to sustain hominins throughout multiple environments.
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FIGURE 7 | Predictive performance of species distribution models with different algorithms as measured with AUC versus distance of extrapolation in environmental space in a novel geographic region. Distance was measured by first normalizing the distance along each variable axis, then calculating Euclidean distance, and finally dividing by the square root of the number of dimensions (i.e., 19) to obtain a normalized distance in standard-deviation units.
A Test of Species Distribution Model Transferability Across Environmental and Geographic Space for 108 Western North American Tree Species

July 2021

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277 Reads

Predictions from species distribution models (SDMs) are commonly used in support of environmental decision-making to explore potential impacts of climate change on biodiversity. However, because future climates are likely to differ from current climates, there has been ongoing interest in understanding the ability of SDMs to predict species responses under novel conditions (i.e., model transferability). Here, we explore the spatial and environmental limits to extrapolation in SDMs using forest inventory data from 11 model algorithms for 108 tree species across the western United States. Algorithms performed well in predicting occurrence for plots that occurred in the same geographic region in which they were fitted. However, a substantial portion of models performed worse than random when predicting for geographic regions in which algorithms were not fitted. Our results suggest that for transfers in geographic space, no specific algorithm was better than another as there were no significant differences in predictive performance across algorithms. There were significant differences in predictive performance for algorithms transferred in environmental space with GAM performing best. However, the predictive performance of GAM declined steeply with increasing extrapolation in environmental space relative to other algorithms. The results of this study suggest that SDMs may be limited in their ability to predict species ranges beyond the environmental data used for model fitting. When predicting climate-driven range shifts, extrapolation may also not reflect important biotic and abiotic drivers of species ranges, and thus further misrepresent the realized shift in range. Future studies investigating transferability of process based SDMs or relationships between geodiversity and biodiversity may hold promise.

Extreme climate and crime: Empirical evidence based on 129 prefecture-level cities in China

October 2022

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79 Reads

Climate change is having profound effects on natural and socio-economic systems, especially via extreme climate events. Using panel data from 129 prefectural-level cities in China from 2013 to 2019, this paper explores the effects of extreme climate on crime rates based on a climate index and manual collection of crime data. The results showed that extreme climate has a significant positive effect on crime rates, increasing by 0.035% for every 1% increase in the extreme climate index. This occurs through two mechanistic pathways: reduced agricultural output and lower employment income. The heterogeneity analysis shows that extreme climate has a greater impact on crime rates in eastern areas which are economically developed and have high levels of immigration. This study provides new perspectives on the impact of extreme climate on the economy and society, in which governments can actively participate in climate governance through environmental protection, energy conservation and emission reduction, and technological innovation to reduce crime rates by reducing the occurrence of extreme climate.

FIGURE 1 | Satellite image of the study area obtained from Google Earth showing the location of the sites discussed in the main text. 
FIGURE 2 | Age models of the sites discussed in this study constructed with the Bacon package for R. The probability distribution of the individual calibrated radiocarbon dates are shown in blue. The 95% confidence of the age model is shown in gray, the median probability age of the age model is shown with a red line. 
FIGURE 3 | Percentage variation of selected taxa in the sites discussed in this study (fine gray lines) and weighted running means of individual taxa (solid colored lines). The dashed vertical rectangles highlight two conspicuous warm-dry intervals discussed in the Lago Cipreses record. 
FIGURE 4 | Comparison of the Nothofagus and Rumex percentages from Lago Cipreses, Lago Guanaco, Vega Ñandú, and Río Rubens, along with their corresponding macroscopic charcoal records and results of CharAnalysis. The black line corresponds to CHAR, the blue line denotes the calculated background, and the red line a locally defined threshold value. The red filling denotes frequency values above the mean in each site, the + symbol represents statistically significant charcoal peaks, the histogram indicates the magnitude of the statistically significant charcoal peaks. Also shown is the charcoal synthesis curve from southern South America normalized to the modern (1-0.1 ka interval) values. 
Modulation of Fire Regimes by Vegetation and Site Type in Southwestern Patagonia Since 13 ka

April 2018

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310 Reads

The degree to which vegetation and site type have influenced fire regimes through the Holocene has not been investigated in detail in the temperate ecosystems of southern Patagonia. Here we present a first attempt using a paired-basin approach to study the evolution of fire regimes in sectors dominated by humid Nothofagus forests and the xeric Patagonian steppe in the Magallanes region of Chilean Patagonia (51°S). We analyzed sediment cores from two small lakes and a bog located within the same climate zone on opposite sides of the forest-steppe ecotone, ~28 km apart. The position of this biological boundary east of the Andes is controlled by the strength and position of the southern westerly winds, which constitute the sole source of precipitation throughout western Patagonia. Our results indicate that fires have occurred in the study region repeated times over the last ~13,000 years at bi- and tridecadal timescales. Sectors currently dominated by Patagonian steppe feature high frequency and low magnitude of local fires, and vice versa in humid forests. Climate-driven expansion of Nothofagus scrubland/woodland into steppe environments over the last ~4,200 years increased the magnitude and lowered the frequency of fire events, culminating with peak Nothofagus abundance, fire magnitude and frequency during the last millennium. We also detect divergences between lake-based vs. bog-based paleofire histories among paired sites located within the Patagonian steppe, ~12 km apart, which we attribute to local burning of the bog at times of lowered water table. This divergence suggests to us that bog-based vegetation and fire histories exacerbate a local, azonal, signal blurring extra-local or regional regimes, thus accounting for some discrepancies in the Quaternary paleovegetation/paleoclimate literature of southern Patagonia.

FIGURE 1 | Study area, study site and sampling design. (A) Volcano Antisana in the Ecuadorian Andes (extracted from Google map) and location of glacier 15-alpha within the Antisana ice-cap. (B) Map of the 15-alpha glacier between 1997 and 2008. Datum: WGMS 84; unit: UTM. (C) Sampling design: black areas represent the three lateral moraines of years 2001, 2003, and 2005, respectively; these areas were removed the species-area analyses because providing undesirable heterogeneity in the topography and granulometry. (D) Distribution of plots (1 m 2 ).
FIGURE 3 | PCA biplot combining diversity variables with microclimatic variables and the distance from the glacier on 120 plots. Each plot represented with a symbol assigned to one glacial retreat strip. Larger symbols represent the mean location of plots in each strip.
FIGURE 4 | Species-area curves at each glacial retreat strip along the chronosequence. Z values (see Preston equation in the section Methods) displayed for each strip. Symbols represent mean values ± SD based on 100 random simulations.
FIGURE 6 | Frequency of plant individuals developing under the shelter of abiotic refuges (nurse rocks) or heterospecific plants (nurse plants) at the community level, along the chronosequence. Mean values and Error bars: 95% CI are showed for each glacial retreat strip; different letters between strips indicate significant variations (post-hoc Tukey tests). The significance and the sign of the two trends were tested with logistic regressions: ***significant at P < 0.001.
Living at the Edge: Increasing Stress for Plants 2–13 Years After the Retreat of a Tropical Glacier

February 2021

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189 Reads

Rapid warming is a major threat for the alpine biodiversity but, at the same time, accelerated glacial retreat constitutes an opportunity for taxa and communities to escape range contraction or extinction. We explored the first steps of plant primary succession after accelerated glacial retreat under the assumption that the first few years are critical for the success of plant establishment. To this end, we examined plant succession along a very short post-glacial chronosequence in the tropical Andes of Ecuador (2–13 years after glacial retreat). We recorded the location of all plant individuals within an area of 4,200 m2 divided into plots of 1 m2. This sampling made it possible to measure the responses of the microenvironment, plant diversity and plants traits to time since the glacial retreat. It also made it possible to produce species-area curves and to estimate positive interactions between species. Decreases in soil temperature, soil moisture, and soil macronutrients revealed increasing abiotic stress for plants between two and 13 years after glacial retreat. This increasing stress seemingly explained the lack of positive correlation between plant diversity and time since the glacial retreat. It might explain the decreasing performance of plants at both the population (lower plant height) and the community levels (lower species richness and lower accumulation of species per area). Meanwhile, infrequent spatial associations among plants indicated a facilitation deficit and animal-dispersed plants were almost absent. Although the presence of 21 species on such a small sampled area seven years after glacial retreat could look like a colonization success in the first place, the increasing abiotic stress may partly erase this success, reducing species richness to 13 species after 13 years and increasing the frequency of patches without vegetation. This fine-grain distribution study sheds new light on nature's responses to the effects of climate change in cold biomes, suggesting that faster glacial retreat would not necessarily result in accelerated plant colonization. Results are exploratory and require site replications for generalization.

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FIGURE 4 (A) 13 C and (B) δ 15 N values measured in charred barley grains from eastern Tianshan complexity (ETC) sites. Dashed lines represent the threshold of "Optimal Water Status" (OWT) and "Superfluous Water Status" (SWT) for barley (Wallace et al., 2013; Vaiglova et al., 2020), and the estimated δ 15 N baseline of local vegetation using average δ 15 N values of archaeological herbivores (Ling et al., 2016).
FIGURE 5 (A) 13 C and (B) δ 15 N values of archaeological barley recovered from Shirenzigou IV of Phase I and Shirenzigou III of Phase II; (C) proportion of barley, arable weeds (excluding water-demanding weeds) and water-demanding weeds in the archaeobotanical assemblages of Shirenzigou IV (Phase I) and Shirenzigou III (Phase II).
FIGURE 6 (A) The typical landscapes of Bronze Age lakeside sites (the excavation area of Haiziyan in 2017) and (B) piedmont sites (the piedmont landscape of Shirenzigou) in the eastern Tianshan region; (C) 13 C and (D) δ 15 N values of archaeological barley from lakeside (Haiziyan, Yanchigucheng) and piedmont sites (Shirenzigou IV, Hongshankou, Kuola); (E) proportion of barley, arable weeds (excluding water-demanding weeds) and water-demanding weeds uncovered from lakeside and piedmont sites.
FIGURE 7 The locations of Shirenzigou IV (SRZ IV, 2,140 m.a.s.l.), Shirenzigou III (SRZ III, 2,200 m.a.s.l.), Haiziyan (HZY, 1,600 m.a.s.l.), Yanchigucheng (YCGC, 2,020 m.a.s.l.), Kuola (KL, 2,200 m.a.s.l.) and Hongshankou (HSK, 2,200 m.a.s.l.) in the eastern Tianshan region. The lowest and highest elevations of Barkol are at Lake Barkol (1,581 m.a.s.l.) and Yueyashan (4,308 m.a.s.l.), respectively. The lowest and highest elevations of Yiwu are at Lake Tuolekule (1,890 m.a.s.l.) and Tuomuerti (4,886 m.a.s.l.), respectively. Maps were generated using ArcMap v. 10.2 with data credit to National Park Service Natural Earth physical map (public domain).
Varying cultivation strategies in eastern Tianshan corresponded to growing pastoral lifeways between 1300 BCE and 300 CE

October 2022

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219 Reads

This study combines plant stable isotope and archaeobotanical analyses to explore how ancient pastoral communities in varying landscapes of eastern Tianshan managed their barley fields. The question is less archaeologically investigated, as recent discussions have focused on pastoral and nomadic activities. Results show that diversified cultivation strategies were employed in barley cultivation at different locations in eastern Tianshan. We also observed a diachronic transition toward less labour-intensive crop management corresponding to a growing pastoral lifeway from the late Bronze Age (1300–800 BCE) to historical periods (400 BCE–300 CE). These results inform us about the mechanism by which southwest Asian originated domesticates were adapted to the Inner Asian environments in the context of the early food globalisation.

Environmental History of Mangrove Vegetation in Pacific West-Central Mexico during the Last 1300 Years

August 2016

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799 Reads

Mangroves are a highly threatened ecosystem due to climate change and human activity, which increases coastal vulnerability. Knowledge about the ecological dynamics of mangroves on a centennial timescale can reveal the different responses in vegetation, which is useful for implementing basic actions for mangrove restoration, conservation and management. A mangrove ecosystem in the Cuyutlán Lagoon area along the Pacific coast of west-central Mexico is significantly altered as a result of industrialization, salt extraction, and road construction. The long-term dynamics of the mangrove ecosystem has also been controlled by Holocene climatic variability. This study reconstructs the environmental history of mangrove vegetation around the Cuyutlán Lagoon during the last ~1300 years in response to periods of human activity and climate change. The reconstruction was performed using paleoecological techniques in sediment cores that include the use of fossil pollen as a proxy for vegetation and magnetic susceptibility and geochemical data (determined by loss-on-ignition and X-ray fluorescence) as a proxy for past environmental changes. The chronology was determined using 14C dating and the age-depth model was constructed by linear interpolation. Redundancy analysis and non-metric multidimensional scaling (NMDS) were used to discern patterns of distribution of the different proxies. Results revealed that the mangrove pollen assemblage of the Cuyutlán Lagoon was dominated by the arboreal taxa Rhizophora mangle, Euphorbiaceae, Moraceae, and Pinaceae, herbaceous taxa like Poaceae, Chenopodiaceae/Amaranthaceae, and aquatics such as Typhaceae and Cyperaceae. NMDS showed a clear separation between two events of human activity—the Spanish Occupation of Colima (~AD 1523-1524) and the opening of the Manzanillo port (~AD 1824-1825). Climate change events such as the Medieval Climate Anomaly (MCA) (~AD 800-1200) and the Little Ice Age (LIA) (~AD 1350-1850) were also successfully identified. The main responses were mangrove expansion (driven by R. mangle) during the LIA and the Manzanillo Port Opening, while the MCA was a highly perturbed period marked by multiple hurricane events and low or no pollen deposition in the sediment. During the Spanish Occupation, the aquatic taxa Typhaceae expanded together with an increase in Ca, Sr and carbonate contents.

Isotopic (δ 2H and δ 13C) tracing the provenance and fate of individual fatty acids fueling migrating animals: A case study of the monarch butterfly (Danaus plexippus)

November 2022

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236 Reads

Introduction Among long-distance migratory insects, the monarch butterfly ( Danaus plexippus ) is one of the most iconic, whose journey is fueled by nectar from flowering plants along the migratory route which may involve up to 3,500 km. Understanding how and where monarchs obtain their dietary resources to fuel migratory flight and ensure overwintering stores would provide new insights into the migratory strategy of this species and subsequently help focus conservation efforts. Methods This pilot study was designed as a first attempt to assess the composition, dynamics, and isotopic (δ ² H, δ ¹³ C) composition of essential and non-essential fatty acids (FA) acquired or manufactured de novo from larval host milkweed ( Asclepias spp.) by monarch butterflies and from adult emergence to overwintering. Results Data from controlled laboratory isotopic tracer tests suggested that adult monarchs convert their dietary energy mainly into 16:0 and 18:1 fatty acids and store them as neutral lipids in their abdomen. FA isotopic composition reflects not only dietary sources but also subsequent isotopic fractionation from metabolism. On the other hand, δ ² H values of essential omega-3 fatty acid alpha-linolenic acid (ALA) correlated with δ ² H Wing , as markers of an individual’s geographic origin and indicated the importance of larval diet. Additionally, in wild-type females, high isotopic fractionation in δ ¹³ C ALA between neutral and polar lipids might indicate increased bioconversion activity during gravidity. Finally, δ ² H LIN showed positive H isotope fractionation from larval dietary sources, indicating that catabolic processes were involved in their manufacture. Furthermore, δ ² H LIN showed a negative correlation with δ ² H Wing values, which could potentially be useful when investigating individual life-history traits, such as migratory catabolic efforts or periods of fasting. Discussion This interpretation was supported by significant larger variations in δ ² H LIN and δ ² H LIN overwintering monarchs compared to other FA. Altogether, our results provide the first evidence that the H isotopic analysis of individual fatty acids in migrating and overwintering monarchs can be used to infer the nutritional history of individuals including the provenance of nectaring sites used to fuel key life history events.


Figure 1: Location map of the selected fossil pollen sites (black dots) and the ecoregion units (colored areas) from the boreal forest taiga biome (adapted from Girardin et al., 2009).
Figure 2: Diversity indices averaged for each ecoregion using 1-ka temporal windows; the site number is indicated in parentheses following ecoregion name labels. (A) α diversity from Shannon entropy number equivalent measurement, (B) β diversity, (C) the temporal (βSORt) diversity based on multisite Sørensen dissimilarity, (D) γ ecoregional total diversity; vertical bars represent the one standard deviation range for calculated indices.
Figure 3: Box plots of diversity indices for the North American boreal forest taiga biome derived from transformed indices. The indices are: (A) α diversity, (B) β diversity (C) γ diversity, (D) βSOR spatial diversity, (E) βSIM spatial turnover component, (F) βNES spatial nestedness component, (G) βSORt temporal diversity, (H) βSIMt temporal turnover component, (I) βNESt temporal nestedness component. Letters indicates significant differences between 1-ka time periods at the 5% confidence level obtained from the Least Significant Difference post-hoc tests. Linear regressions (black line) and associated Spearman correlation p-values are also indicated.
Disentangling the trajectories of alpha, beta and gamma plant diversity of North American boreal ecoregions since 15,500 years

April 2014

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496 Reads

Assessment of biodiversity in a changing world is a key issue and studies on the processes and factors influencing its history at relevant time scales are needed. In this study, we analyzed temporal trends of plant diversity using fossil pollen records from the North American boreal forest-taiga biome (NABT). We selected 205 pollen records spanning the last 15,500 years. Diversity was decomposed into α and γ richness, and β diversity, using Shannon entropy indices. We investigated temporal and spatial patterns of β diversity by decomposing it into independent turnover (variation in taxonomic composition due to species replacements) and nestedness (variation due to species loss) components. The palynological diversity of the NABT biome experienced major rearrangements during the Lateglacial and early Holocene in response to major climatic shifts. The β nestedness likely reflected plant immigration processes and generally peaked before the β turnover value, which mirrors spatial and temporal community sorting related to environmental conditions and specific habitat constraints. Palynological diversity was generally maximal during the Lateglacial and the early Holocene and decreased progressively during the Holocene. These results are discussed according to macro-ecological processes, such as immigration, disturbances, and environmental fluctuations, with climate most notably as the main ecological driver at millennial scales.


Building on 150 Years of Knowledge: The Freshwater Isopod Asellus aquaticus as an Integrative Eco-Evolutionary Model System

November 2021

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178 Reads

Interactions between organisms and their environments are central to how biological diversity arises and how natural populations and ecosystems respond to environmental change. These interactions involve processes by which phenotypes are affected by or respond to external conditions (e.g., via phenotypic plasticity or natural selection) as well as processes by which organisms reciprocally interact with the environment (e.g., via eco-evolutionary feedbacks). Organism-environment interactions can be highly dynamic and operate on different hierarchical levels, from genes and phenotypes to populations, communities, and ecosystems. Therefore, the study of organism-environment interactions requires integrative approaches and model systems that are suitable for studies across different hierarchical levels. Here, we introduce the freshwater isopod Asellus aquaticus , a keystone species and an emerging invertebrate model system, as a prime candidate to address fundamental questions in ecology and evolution, and the interfaces therein. We review relevant fields of research that have used A. aquaticus and draft a set of specific scientific questions that can be answered using this species. Specifically, we propose that studies on A. aquaticus can help understanding (i) the influence of host-microbiome interactions on organismal and ecosystem function, (ii) the relevance of biotic interactions in ecosystem processes, and (iii) how ecological conditions and evolutionary forces facilitate phenotypic diversification.

Complex (multispecies) livestock keeping: Highland agricultural strategy in the northern Horn of Africa during the Pre-Aksumite (1600 BCE–400 BCE) and Aksumite (400 BCE–CE 800) periods

November 2022

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127 Reads

The earliest settlements and states in the Horn of Africa were founded in mid to high-elevation areas by farmers and herders who were pioneers in agriculture and herding. Even today, places between mid- and high-elevation remain densely populated. The ancient Pre-Aksumites and Aksumites (1600 cal BCE–800 cal CE) of the north Ethiopian and Eritrean highlands established one of the most powerful states in the Horn of Africa in these high elevation areas through control of long-distance trade and intensive and extensive agriculture. However, despite the fact that agriculture was a significant source of wealth and subsistence for these ancient polities, there has been little research into the agricultural strategies of Pre-Aksumite and Aksumite societies. Using archaeological and faunal data collected from the site of Mezber dating from 1600 cal BCE to 400 cal CE, as well as prevsiously published data, this article provides zooarchaeological evidence for the earliest farming practices in the Horn of Africa. The research demonstrates a resilient highland agricultural strategy based on multispecies animal and plant resources, similar to most tropical agricultural systems today. A second important strategy of Pre-Aksumite farmers was the incorporation of both indigenous and exogenous plants and animals into their subsistance strategies. The Mezber site also offers one of the most thoroughly collected data to support multispecies farming practice in the north Ethiopian and Eritrean highlands.

Island ecosystem responses to the Kuwae eruption and precipitation change over the last 1600 years, Efate, Vanuatu

February 2023

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236 Reads

Introduction Islands of the Southwest Pacific are exposed to geologic and climate-related disturbances that occur on a range of timescales and which probably affect, to varying degrees, their terrestrial ecosystems. Over the past ∼1100 years we know of two major events in the region: the Kuwae eruption which is thought to have occurred ∼500 cal. years BP and a shift to drier conditions which began ∼1100 cal. years BP. Methods We investigated terrestrial and lacustrine ecosystem responses to these events and also to a changing fire regime, likely human-caused, using a multi-proxy (C/N, charcoal, chironomids, pollen, and tephra) record from Lake Emaotul, Efate, Vanuatu. Results Tephra from the Kuwae eruption was found across a 6 cm layer which our age-depth model suggests was deposited 650–510 cal. years BP (95% confidence). Forest and chironomid community turnover increased during the wet-dry shift 1100–1000 cal. years BP; subsequently, chironomid turnover rates decreased again within <135 years and vegetation had partially (but not fully) recovered after ∼80 years. Following Kuwae volcanic tephra deposition, vegetation turnover increased again, reflecting a reduction in small trees and shrubs and an increase in grasses. Subsequently, the forest vegetation did not regain its previous composition, whereas chironomid community composition remained fairly stable before and after tephra deposition. Within the last ∼90 years, enhanced local burning drove another increase in vegetation turnover. Discussion Terrestrial and freshwater ecosystems in Efate are sensitive to changes in hydroclimate, volcanism, and anthropogenic fires, although to different degrees; while recent human impacts are often obvious, volcanic eruptions and climatic shifts have also structured Pacific-island ecosystems and will continue to do so.

FIGURE 1 | Sampling sites of alpine grasslands on the Tibetan Plateau.
FIGURE 4 | Species importance point map according to the importance of the top 30 soil bacteria at the genus level of alpine grasslands on the Tibetan Plateau.
FIGURE 5 | Non-metric multidimensional scaling (NMDS) analysis of the soil bacteria in alpine grasslands on the Tibetan Plateau. Different shaped dots represent the samples from different alpine grassland types, and the bumps of the samples bound the faces of different colors. AD, alpine desert; ADS, alpine desert steppe; AM, alpine meadow; AMS, alpine meadow steppe; AS, alpine steppe.
Alpha diversity indices of soil bacterial communities (mean ± SE) in alpine grasslands on the Tibetan Plateau.
Analysis of similarities (ANOSIM) of soil bacteria in alpine grasslands on the Tibetan Plateau.
Soil Bacterial Communities and Diversity in Alpine Grasslands on the Tibetan Plateau Based on 16S rRNA Gene Sequencing

February 2021

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152 Reads

The Tibetan Plateau, widely known as the world’s “Third Pole,” has gained extensive attention due to its susceptibility to climate change. Alpine grasslands are the dominant ecosystem on the Tibetan Plateau, albeit little is known about the microbial community and diversity among different alpine grassland types. Here, soil bacterial composition and diversity in the upper soils of five alpine grassland ecosystems, alpine meadow (AM), alpine steppe (AS), alpine meadow steppe (AMS), alpine desert (AD), and alpine desert steppe (ADS), were investigated based on the 16S rRNA gene sequencing technology. Actinobacteria (46.12%) and Proteobacteria (29.67%) were the two dominant soil bacteria at the phylum level in alpine grasslands. There were significant differences in the relative abundance at the genus level among the five different grassland types, especially for the Rubrobacter, Solirubrobacter, Pseudonocardia, Gaiella, Haliangium, and Geodermatophilus. Six alpha diversity indices were calculated based on the operational taxonomic units (OTUs), including Good’s coverage index, phylogenetic diversity (PD) whole tree index, Chao1 index, observed species index, Shannon index, and Simpson index. The Good’s coverage index value was around 0.97 for all the grassland types in the study area, meaning the soil bacteria samplings sequenced sufficiently. No statistically significant difference was shown in other diversity indices’ value, indicating the similar richness and evenness of soil bacteria in these alpine grasslands. The beta diversity, represented by Bray–Curtis dissimilarity and the non-metric multidimensional scaling (NMDS), showed that OTUs were clustered within alpine grasslands, indicating a clear separation of soil bacterial communities. In addition, soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), pH, and soil water content (SWC) were closely related to the variations in soil bacterial compositions. These results indicated that soil bacterial taxonomic compositions were similar, while soil bacterial community structures were different among the five alpine grassland types. The environmental conditions, including SOM, TN, TP, pH, and SWC, might influence the soil bacterial communities on the Tibetan Plateau.

Surface microbiota of Mediterranean loggerhead sea turtles unraveled by 16S and 18S amplicon sequencing

July 2022

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159 Reads

The loggerhead sea turtle is considered a keystone species with a major ecological role in Mediterranean marine environment. As is the case with other wild reptiles, their outer microbiome is rarely studied. Although there are several studies on sea turtle’s macro-epibionts and endo-microbiota, there has been little research on epibiotic microbiota associated with turtle skin and carapace. Therefore we aimed to provide the identification of combined epibiotic eukaryotic, bacterial and archaeal microbiota on Mediterranean loggerhead sea turtles. In this study, we sampled skins and carapaces of 26 loggerheads from the Mediterranean Sea during 2018 and 2019. To investigate the overall microbial diversity and composition, amplicon sequencing of 16S and 18S rRNA genes was performed. We found that the Mediterranean loggerhead sea turtle epibiotic microbiota is a reservoir of a vast variety of microbial species. Microbial communities mostly varied by different locations and seas, while within bacterial communities’ significant difference was observed between sampled body sites (carapace vs. skin). In terms of relative abundance, Proteobacteria and Bacteroidota were the most represented phyla within prokaryotes, while Alveolata and Stramenopiles thrived among eukaryotes. This study, besides providing a first survey of microbial eukaryotes on loggerheads via metabarcoding, identifies fine differences within both bacterial and eukaryotic microbial communities that seem to reflect the host anatomy and habitat. Multi-domain epi-microbiome surveys provide additional layers of information that are complementary with previous morphological studies and enable better understanding of the biology and ecology of these vulnerable marine reptiles.

FIGURE 1 Physical locations (A), genetic diversities (B), and forensic efficiency evaluations (C) of 17 X-chromosomal Multi-InDels in Beijing Han (CHB) and Southern Han (CHS) populations. For genetic diversities, different colors represented different expected heterozygosity (He) values: red and blue denote small and large He values, respectively; the size of shape is proportional to the number of alleles observed in each locus.
FIGURE 2
FIGURE 3 Population genetic analyses of different continental populations based on selected 17 loci. (A) Pairwise F ST distances of different continental populations. Different colors represented different F ST values: red denoted small F ST values; blue denoted large F ST values. (B) Multi-dimensional analysis of different continental populations. (C) The phylogenetic tree of different continental populations.
General information of 17 selected Multi-InDel loci on the X chromosome.
Development and forensic efficiency evaluations of a novel multiplex amplification panel of 17 Multi-InDel loci on the X chromosome

October 2022

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49 Reads

Multi-InDel, as the novel genetic markers, showed great potential in forensic research. Whereas, most scholars mainly focused on autosomal Multi-InDels, which might provide limited genetic information in some complex kinship cases. In this study, we selected 17 Multi-InDels on the X chromosome and developed a multiplex amplification panel based on the next-generation sequencing (NGS) technology. Genetic distributions of these 17 loci in Beijing Han, Chinese Southern Han, and the studied Guizhou Han populations revealed that most loci showed relatively high forensic application values in these Han populations. In addition, more allelic variations of some loci were observed in the Guizhou Han than those in Beijing Han and Southern Han populations. Pairwise F ST values, multi-dimensional analysis, and phylogenetic tree of different continental populations showed that selected 17 loci generally could differentiate African, European, East Asian, and South Asian populations. To sum up, the developed panel in this study is not only viewed as the high-efficient supplementary tool for forensic individual identification and paternity analysis, but it is also beneficial for inferring biogeographical origins of different continental populations.

Changes in Soil Chemistry After 17 Years in Urban and Rural Forest Patches

February 2022

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103 Reads

Cycling of carbon (C), nitrogen (N), calcium (Ca), phosphorus (P), and sulfur (S) is an important ecosystem service that forest soils provide. Humans influence these biogeochemical processes through the deposition of atmospheric pollutants and site disturbances. One way to study these potential anthropogenic trajectories is through long-term monitoring in association with human-caused environmental gradients such as urban-rural gradients. The objective of this study was to characterize changes in surface soil chemistry of urban, suburban and rural forest patches in the Baltimore Metropolitan area. Soil composite samples (0–10 cm) were analyzed for macro- and micronutrients, pH, and C. A total of 12 sites in forest patches dominated by white oak ( Quercus alba ) and tulip poplar ( Liriodendron tulipifera ) were established in 2001, and resampled in 2018. We hypothesized that after almost two decades (1) concentrations of N, Ca, and P, as well as soil pH would be higher, especially in urban forest patches due to local deposition; (2) S levels would be lower due to decreased regional atmospheric deposition and; (3) total soil C would increase overall, but the rate of increase would be higher in the urban end of the gradient due to increased NPP. Overall, means of Ca concentration, pH, and C:N ratios significantly changed from 2001 to 2018. Calcium increased by 35% from 622 to 844 mg kg –1 , pH increased from 4.1 to 4.5, and C:N ratios decreased from 17.8 to 16.7. Along the gradient, Ca, N, P, and S were statistically significant with Ca concentration higher in the urban sites; S and N higher in the suburban sites; and P lower in the urban sites. Confounding factors, such as different geologic parent material may have affected these results. However, despite the unique site conditions, patterns of surface soil chemistry in space and time implies that local and regional factors jointly affect soil development in these forest patches. The increase in pH and Ca is especially notable because other long-term studies demonstrated changes in the opposite direction.

Figure 1: Location of Wombat Pool and other cites mentioned in the text. (A) Regional map; (B) map of Cradle Mountain-Lake St Clair National Park; (C) satellite image of site and surrounding area. Circle = lake or marine sediment record, triangle = archeological site, square = speleothem record, star = Wombat Pool, black line = Cradle Mountain-Lake St Clair National Park boundary, white x = coring location.
TABLE 1 | Radiocarbon dating results.
Figure 2: Lithology. Lithology, radiocarbon dates, magnetic susceptibility, and density for the Wombat Pool cores. The asterisk indicates the date that was not used in the chronology.
Figure 3: Age-depth model. Age-depth model for Wombat Pool (black line). The 95% confidence intervals are shown as gray shading. The distributions of the calibrated radiocarbon ages that were used to develop the model are shown in blue, and the date that was not included in the model is indicated in red.
Figure 4: Pollen diagram for percentage of selected taxa from Wombat Pool. Note differing scales on x-axes. Stippled gray shading indicates 10x exaggeration (i.e., Bauera rubioides and Melaleuca), solid gray shading indicates 5x exaggeration, and white shading indication 2x exaggeration. Isoetes values were divided by 50 to aid readability.
A 17,000-Year-Long Record of Vegetation and Fire from Cradle Mountain National Park, Tasmania

July 2016

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452 Reads

On centennial to millennial timescales fire regimes are driven by climate changes, vegetation composition and human activities. We reconstructed the postglacial vegetation and fire history based on pollen and charcoal data from a small lake in Cradle Mountain National Park and investigated the influence that climate, people, and vegetation had on past fire regimes. In the late-glacial period, a slowly warming climate led to a shift in vegetation from coniferous alpine shrubland to Phyllocladus woodland. During this period, fire activity was very low. The initial increase in fires occurred between 12,500–11,000 cal yr BP and led to a decline in forest taxa, a resurgence of grasses and a rise in the pyrophytic buttongrass Gymnoschoenus. The highest fire activity in the record occurred between 10,900–9400 cal yr BP, the warmest interval of the postglacial period based on independent proxy records. Subalpine trees had depressed levels of pollen during this time. After 9000 cal yr BP, fire activity declined substantially, and fire-sensitive rainforest reached its maximum extent ca. 8500–6500 cal yr BP. A major fire perturbation occurred ca. 3,600 cal yr BP, and thereafter rainforest shifted to open Eucalyptus woodland. The comparison of reconstructed fire and vegetation history at Wombat Pool to climate records and archeological data indicated that climate was the primary driver of the observed changes. In the late glacial and early Holocene, climate warming and individual species dispersal traits likely drove changes in vegetation composition that in turn impacted the fire regime. A relatively wet mid-Holocene climate favored rainforest trees whereas the drier and more variable climate of the late Holocene contributed to a decline in rainforest and a shift toward mixed forest as wet sclerophyll elements increased. Archeological evidence suggests humans reoccupied the region ca. 4000 cal yr BP. This may have added an ignition source that was absent in the previous ca. 7000 years and may have contributed to the large fire event ca. 3600 cal yr BP. Although pre-European populations may have been a source of ignition locally, the reconstructed fire history trends from Cradle Mountain National Park match well with large-scale changes in climate patterns.

Agriculture in the Karakum: An archaeobotanical analysis from Togolok 1, southern Turkmenistan (ca. 2300–1700 B.C.)

September 2022

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477 Reads

Southern Central Asia witnessed widespread expansion in urbanism and exchange, between roughly 2200 and 1500 B.C., fostering a new cultural florescence, sometimes referred to as the Greater Khorasan Civilization. Decades of detailed archeological investigation have focused on the development of urban settlements, political systems, and inter-regional exchange within and across the broader region, but little is known about the agricultural systems that supported these cultural changes. In this paper, we present the archaeobotanical results of material recovered from Togolok 1, a proto-urban settlement along the Murghab River alluvial fan located in southeastern Turkmenistan. This macrobotanical assemblage dates to the late 3rd - early 2nd millennia B.C., a time associated with important cultural transformations in southern Central Asia. We demonstrate that people at the site were cultivating and consuming a diverse range of crops including, barley, wheat, legumes, grapes, and possibly plums and apples or pears. This, together with the associated material culture and zooarchaeological evidence, suggest a regionally adapted mixed agropastoral economy. The findings at Togolok 1 contribute to the ongoing discussion of dietary choices, human/landscape interactions, and the adaptation of crops to diverse ecosystems in prehistoric Central Asia.

Effects of Climate Change vs. Grazing Exclusion on Species Diversity Over 18 Years Along an Elevation Gradient in the European Alps

July 2021

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157 Reads

Climate change was already shown to increase species numbers in high elevations. In contrast, grazing might interfere with climate change effects. To disentangle both the effects remains a major challenge of alpine ecology. The present study investigated both the effects on species diversity along an elevation gradient in the Austrian Central Alps. We aimed to answer the following questions: How do species diversity and frequency of subalpine–alpine–subnival plant communities change in grazed sites with time? Do competitive plant species increase in the communities? How does grazing exclusion affect species diversity, functional groups, and strategy types? Are environmental changes (temperature, sunshine duration, precipitation) responsible for diversity changes or does grazing override climate effects? The study was carried out for 18 years along an elevation gradient from 1,958 to 2,778 m a.s.l. at Obergurgl (Tyrol, Austria), including six different plant communities. A total of 11 grazing exclusions were established. At each community, the frequency of the species was counted in 1 m2 plots yearly or at least every 3–4 years. Environmental data were obtained from the weather station Obergurgl. Changes of the community parameters and the species composition were analyzed by partial redundancy analyses and mixed-effect models. Species diversity increased with time at all grazed sites, but this increase was suppressed under grazing exclusion. Grazing exclusion effects became pronounced after 5 years. The most consistent result was the increase of bryophytes throughout. At the subalpine grassland, tall-growing species expanded in the exclosures; at the upper alpine Carex curvula grassland, snow bed species decreased with grazing exclusion. Among the environmental factors, sunshine duration of the previous year’s autumn quartal was found to be the essential variable for the changes. We concluded that diversity increases in grazed communities of the Austrian Central Alps can be attributed to climate change. An indication of slightly reduced and altered weather effects under grazing exclusion was found.

FIGURE 1 | Global molecular phylogeny of trap-jaw ants reconstructed under Bayesian inference used to ancestral chromosome reconstruction. Clades A-G are highlighted in different colors. Morphological groups proposed by Brown (1978), are shown at the right side of the tree. The outgroup can be found at the top of the figure in light purple.
FIGURE 2 | Ancestral haploid chromosome state reconstruction inferred under Bayesian Inference and Maximum Likelihood methods. The ancestral chromosome number with the highest probability or with the best likelihood are denoted at the main nodes. The colors of branches represent each given chromosome number according to the legend. The known karyotypes of species are given at the tip. An ideogram was estimated from the available karyotypic formulae (in bold), denoting the number of metacentric, submetacentric, subtelocentric, and telocentric chromosomes along the phylogeny.
FIGURE 3 | Chromosome number evolution and inferred ancestral chromosome state in the trap-jaw ants inferred under Bayesian and Maximum likelihood optimization. Number at the nodes and respective colors (see label) present the inferred ancestral haploid chromosome. Numbers at the tips are the known haploid chromosome numbers of species. At right of each clade of Anochetus and Odontomachus are depicted the general chromosome morphology comprising the karyotypes. At each branch are highlighted the likely rearrangements undergone during karyotype evolution (see "Discussion" for details).
Support values for Bayesian Inference Posterior Probability (PP) and Maximum Likelihood (BS) with the respective groups of the genus Anochetus and Odontomachus.
Phylogenetic Reconstruction of the Ancestral Chromosome Number of the Genera Anochetus Mayr, 1861 and Odontomachus Latreille, 1804 (Hymenoptera: Formicidae: Ponerinae)

February 2022

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210 Reads

Recent phylogenetic and molecular data are changing our knowledge about the relations between species and evolutionary processes resulting in the chromosome variation observed in ants (Hymenoptera: Formicidae). Ants exhibit remarkable variations in morphology, behavior, karyotypes, and chromosome structure. By assembling genetic and chromosome information about the trap-jaw ants from the subfamily Ponerinae, we reconstructed the phylogenetic relationships that inferred the monophyletic condition between the Anochetus and Odontomachus genera and estimated their ancestral haploid chromosome number. According to our inferences, these clades have an ancestral haploid chromosome number n = 15. The most recent common ancestor of Anochetus and Odontomachus has arisen between the Early Paleocene and the Early Eocene periods (time of the most recent common ancestor). In the Anochetus genus, we observed maintenance of the ancestral chromosome number estimated here in most species. This also suggests that pericentric inversions were the primary chromosomal rearrangement modulating the karyotype evolution of this genus. However, a reduction from n = 15–14 is observed in Anochetus emarginatus and Anochetus cf. madaraszi , which likely occurred by centromeric fusion. In contrast, the increase from the ancestral karyotype number in Anochetus horridus suggested centromeric fissions. Odontomachus showed maintenance of the ancestral chromosome number in the “ rixosus group” and several gains in all species from the “ haematodus group.” Our findings suggest that centromeric fissions and pericentric rearrangements lead to chromosomal changes in trap-jaw ants. Considering the ancestral state estimated here, changes in chromosome morphology are likely due to pericentric inversions, and chromosome number increases are likely due to centric fissions. The higher number of acrocentric or telocentric chromosomes in the karyotypes with n < 15 haploid chromosomes supports such an idea.

Octopus Fishing and New Information on Ecology and Fishing of the Shallow-Water Octopus Callistoctopus furvus (Gould, 1852) Based on the Local Ecological Knowledge of Octopus Fishers in the Marine Ecoregions of Brazil

April 2022

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138 Reads

Studies that compile local ecological knowledge (LEK) on some of the various species of living beings observe biological data and are notably fundamental for effectively managing fisheries, supporting management strategies for protected areas, species conservation, and other factors. In this study, ethnoecological approaches were used to focus on the octopus Callistoctopus furvus (Gould, 1852), recently re-described and re-presented to the academic community more than a century after its discovery. The LEK of octopus fishers from different marine ecoregions of Brazil was compared to identify the distribution limits of the species along the Brazilian coast. Semi-structured interviews were conducted in 16 municipalities across four marine ecoregions located between the states of Ceará (northern limit) and Santa Catarina (southern limit), between March 2018 and August 2019. The results of the 187 interviews indicated a traditionality of fishing among artisanal octopus fishers, who are mostly men, although some are women who also share information on the fishing of C. furvus and hold leadership positions in the fishing colony. Cronbach’s alpha was used to analyze reliability of the form used in the interviews. A logistic regression model with binomial distribution was used to assess whether the probability of capturing the “eastern octopus” was associated with some of the interview variables. A cluster analysis based only on the respondents who caught the “eastern octopus” indicated the formation of groups and revealed greater dissimilarities among the fishers from the southeastern marine ecoregion of Brazil due to the fishing method used in the region. Heat maps showed that most of the information on the species was obtained in the eastern marine ecoregion of Brazil. The occurrence of the “eastern octopus” was recorded in all the studied Brazilian marine ecoregions. Moreover, this study revealed the relevant contribution of fishers’ knowledge to the distribution diagnosis of species with scarce scientific information.


FIGURE 1
FIGURE 2 (A) Relative abundance of eukaryotic classes from filtered 18S samples rarefied to 500 reads. Most samples are dominated by reads from members of the Nematoda and Ascomycota. Samples are split between those collected in the wet and dry seasons. While all monkeys were initially sampled in both wet and dry seasons, not all samples survived filtration and rarefaction steps, limiting our ability to exhaustively include samples from the same monkeys in both seasons. (B) Violin plots of the Chao 1 diversity of 56 fecal samples collected from 25 wild capuchin monkeys (Cebus imitator) in the dry season and wet season of 2014 in the tropical dry forest of A ́ rea de Conservacion Guanacaste, Costa Rica. Taxa classified as helminths are plotted on the right and non-dietary eukaryotes on the left. Alpha diversity is significantly higher, with low effect sizes, in the wet season samples.
FIGURE 4
Promise and limitations of 18S genetic screening of extracted fecal DNA from wild capuchins
  • New
  • Article
  • Full-text available

August 2023

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30 Reads

Genomic screening of fecal DNA provides insight into diet, parasite infection dynamics, and other aspects of the ecology and pathogens of wild populations. Here, we amplify and sequence the V4/V5 regions of the eukaryotic 18S ribosomal RNA gene from fecal DNA of wild capuchin monkeys ( Cebus imitator ). We collected 94 fecal samples from 26 individuals, each sampled 1-4 times across a 19-month period and examined the eukaryotic diversity in 63 of these samples which had sufficient numbers and quality of reads during downstream analyses. We found a total of 234 distinct amplicon sequence variants (ASVs) classified as Eukaryotes in our samples. Of these, 66 were assigned to the phylum Nematoda. 64 ASVs are from taxa that possibly parasitize monkeys or their food items: 33 were assigned to lungworms (Superfamily Metastrongyloidae; genus Angiostrongylus ), two to the genus Strongyloides , and one to the genus Austrostrongylus . The remaining 28 ASVs were assigned to nematodes that likely parasitize plants and/or invertebrates that the monkeys consume. Taken together with past dietary and coprological study of the same primate population, our results suggest that invertebrate consumption and parasitic infection, especially by lungworms, is common and widespread among this population of wild monkeys. We also discuss limitations of our approach, including the amplification of off-target ASVs, and make suggestions for future research. Overall, 18S screening shows promise for identifying various components of the capuchin gastrointestinal eukaryotic ecosystem, including parasitic helminths, and its utility will increase with the improvement of genetic databases.

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