Range Of Species Research Articles

Natural enemies of Lemna minuta in its native range and their potential as biological control agents for Europe

ABSTRACT Lemna minuta is native to North America but an invasive alien plant in Europe, where it poses significant threats to freshwater ecosystems. Explorations for biological control agents were conducted in two regions of the United States (Louisiana and California), revealing three candidate species. Subsequent laboratory investigations focused on the weevil Tanysphyrus lemnae and the fly Lemnaphila scotlandae as the most promising agents and confirmed that both the herbivorous insects attack L. minuta plants. To evaluate the host specificity of these two potential agents, insects were exposed to five species of duckweed commonly occurring in North America and Europe. Preliminary host-range testing indicated that T. lemnae develops on all evaluated duckweed species, including those from different genera (Lemna, Spirodela, Landoltia). Conversely, data revealed that feeding and development of the dipteran L. scotlandae are limited to species in the genus Lemna, but this includes L. minor, a native European species threatened in Europe due to the spread of L. minuta. No-choice and choice tests confirmed that neither larvae nor adults of L. scotlandae discriminate between the two Lemna species, except for pupation, which occurs more frequently in L. minor under choice conditions. We conclude that the broad host-range of T. lemnae and L. scotlandae render them unsuitable as biological control agents of L. minuta in Europe.

The marriage between stable isotope ecology and plant metabolomics - new perspectives for metabolic flux analysis and the interpretation of ecological archives.

Even though they share many thematical overlaps, plant metabolomics and stable isotope ecology have been rather separate fields mainly due to different mass spectrometry demands. New high-resolution bioanalytical mass spectrometers are now not only offering high-throughput metabolite identification but are also suitable for compound- and intramolecular position-specific isotope analysis in the natural isotope abundance range. In plant metabolomics, label-free metabolic pathway and metabolic flux analysis might become possible when applying this new technology. This is because changes in the commitment of substrates to particular metabolic pathways and the activation or deactivation of others alter enzyme-specific isotope effects. This leads to differences in intramolecular and compound-specific isotope compositions. In plant isotope ecology, position-specific isotope analysis in plant archives informed by metabolic pathway analysis could be used to reconstruct and separate environmental impacts on complex metabolic processes. A technology-driven linkage between the two disciplines could allow us to extract information on environment-metabolism interaction from plant archives such as tree rings but also within ecosystems. This would contribute to a holistic understanding of how plants react to environmental drivers, thus also providing helpful information on the trajectories of the vegetation under the conditions to come.

Population genetics of Babesia vogeli based on the mitochondrial cytochrome b gene

The current study aimed at population genetic characterization of B. vogeli based on the cytochrome b (cyt b) gene sequences (≥ 685 bp) available in the GenBank. Phylogenetic trees placed all the sequences of B. vogeli in a single large monophyletic clade; however, it was further divided into two subclades (Bv1 and Bv2). Out of seven nucleotide variations observed between Bv1 and Bv2 subclades, four were synonymous (G92A, C170T, T488C and A659G), and three were non-synonymous (G324A, C438A and G465A) resulting in amino acid substitutions at three places (V108I, L146I and V155I). Within different B. vogeli populations, the nucleotide and haplotype diversities were low. The median-joining haplotype network revealed only two haplotypes (Hap_1 and Hap_2). A geographical sub-structuring was noticed in the B. vogeli populations, with moderate genetic differentiation (FST = 0.05000; P < 0.05) and a very high gene flow (Nm = 4.75) between Indian and Chinese populations. Neutrality tests and mismatch distributions for the Indian population and the overall dataset of B. vogeli indicated a constant population size. This study provides the first insight into the genetic characterization, population genetics and haplotype network of B. vogeli based on the cyt b gene.

Genomic diversity of major tree species in the Eurasian relict forests of northern Iran

We investigated population genetics of the native tree species Acer velutinum Boiss., Fagus orientalis Lipsky, and Quercus castaneifolia C.A. Mey. in the Hyrcanian forests of northern Iran and also F. orientalis populations in the Euro-Siberian and Colchic subregions of northern Türkiye. We used the double-digest RADseq method and genotyped 90 populations and 1,589 individuals across the distribution range of the species. Genome-wide SNPs from 28 populations of A. velutinum, 32 populations of F. orientalis, and 30 Q. castaneifolia revealed higher genetic differentiation among A. velutinum populations than among F. orientalis and Q. castaneifolia. The global FST value was lowest for F. orientalis populations and highest for A. velutinum populations, while the global FIS value was negative for A. velutinum. Demographic history analysis revealed a bottleneck during the last glacial period (11,500—115,000 Kya) for the A. velutinum populations with reduced effective population size (Ne). All three species show multiple bottlenecks and reduced Ne during the Quaternary. Pronounced genetic divergence among A. velutinum populations in the Hyrcanian forests compared to the other two species suggests cryptic speciation. Conversely, F. orientalis and Q. castaneifolia populations showed low levels of genetic structure, suggesting that species-specific factors, such as pollen production and pollination efficiency, may have influenced the genetic patterns within these species in similar environments. The nucleotide diversity of F. orientalis populations in Iran is negatively correlated with altitude (p = 0.046). In contrast, A. velutinum populations show a significant correlation between nucleotide diversity and longitude (p = 0.008). Furthermore, the F. orientalis populations from Türkiye showed a distinct west–east genetic structure and were highly diverged from the Iranian F. orientalis populations.

Notes on the natural history and identity of the pelagic sea snake Hydrophis platurus (Serpentes: Elapidae) from Golfo Dulce, Puntarenas, Costa Rica

Introduction: The pelagic sea snake Hydrophis platurus has the broadest distributional range of all the snakes and is the only sea snake of tropical waters off the west coast of the Americas. Within the variation in the color pattern of this species, completely yellow specimens were considered very rare or occasional. However, a yellow pattern dominates a population established in the interior of the Golfo Dulce in the Southern Pacific of Costa Rica. Objective: We studied the abundance, activity patterns, morphometry, and feeding behavior of the yellow H. platurus within the Golfo Dulce. Methods: Between February 2009 and July 2018, we conducted surveys for sea snakes from a boat within the perimeter of the Golfo Dulce. Results: Adults from the gulf population are smaller than the bicolor oceanic population, with females having larger bodies. Sea snakes within the gulf float and move with surface currents without being linked to drift lines and debris. These snakes are mainly found in clean, calm waters with little turbulence. They feed on a wide diversity of small fish, which they capture using passive stalking predatory behaviors floating on the surface. Prey are quickly captured and swallowed alive. This species has an almost total absence of predation, a pattern that extends to this yellow population. Conclusions: The characteristics of the gulf and the direction and strength of the surface currents at its entrance might restrict the transit of this yellow population to the outside and the entry of the bicolored snakes of the oceanic population. We do not consider making taxonomic changes in this Golfo Dulce population prudent. This yellow population is relatively common within the basin. However, the high tourist traffic and other activities are risk factors for its conservation. Protection policies must be created to preserve and protect this small population of yellow sea snakes unique within this species' distribution range.

Species Distribution Models for Mesopelagic Mesozooplankton Community

ABSTRACTAimWe aimed to enhance our understanding of the distribution of mesopelagic mesozooplankton (MM) using species distribution models, assess the performance of various modelling techniques, identify key environmental predictors for MM distribution and compute their habitat suitability indices.LocationOur study focused on the mesopelagic zone globally, with data analysed from different oceans.TaxonOur focus was primarily on mesopelagic mesozooplankton, gathering data on 861 different species from the Mesopelagic Mesozooplankton and Micronekton (MMM) Database.MethodsWe used an ensemble of species distribution models, applying 10 different modelling algorithms and three multi‐model ensemble approaches. We explored two important factors that can affect model performance: subsampling and the choice of background points. We also estimated the relative importance of various environmental conditions such as mixed layer depth, temperature, salinity, net primary productivity, euphotic zone depth and dissolved nitrate concentration on the distribution of these species.ResultsEuphotic zone depth, salinity and dissolved nitrate concentration were identified as the most important variables for explaining the distribution of mesopelagic mesozooplankton. The ensemble modelling results were robust in areas with abundant observational records, but high uncertainty was observed in data‐limited regions. We found a patchy habitat suitability map for zooplankton when modelled within their native range, largely due to uneven sampling. Unrestricted range models yielded smoother patterns but could inaccurately project species in areas where they do not occur.Main ConclusionsOur study highlights the need for increased sampling effort in data‐limited regions to improve the accuracy of mesopelagic species distribution models. Despite some inaccuracies, unrestricted range models, assuming ecological equivalence (where different species occupying a similar ecological niche in different geographical regions or different ecosystems exhibit similar adaptations and behaviours), provide a reasonable comparison for habitat suitability maps and model performance. It also confirms the significant impact of certain environmental conditions on mesozooplankton distribution.

Shedding light on the geographical distribution, population size and inflorescence coloration variety of Royal Irises (Iris section Oncocyclus) family in West Bank, Palestine

Palestine has rich floristic diversity due to its location, diverse biogeographical zones, and various topographical features. The Royal Irises (Iris section Oncocyclus), are a monophyletic group of herbaceous geophytes, consisting of 33 species, endemic to the Middle East. Within the West Bank of Palestine, three Royal Irises are documented. However, their distribution, population size, and status are not studied comprehensively. This study focused on evaluating the occurrence, distribution range, population size, status, number of flowers, inflorescence coloration variety, and habitats of the vulnerable and endemic Iris haynei, the endangered and sub-endemic Iris lortetii, and the vulnerable and sub-endemic Iris atrofusca. I. lortetii was found in 10 sites within Nablus district, with more than 12625 clones and 25088 flowers flowers recorded. I. haynei were documented in 4 sites within Jenin district, three are new to science, where 10729 clones and 9562 flowers were recorded. I. atrofusca was reported in 13 localities in Tubas and Ramallah districts, where 1853 clones and 8460 flowers were recorded, whereas six locatities are new to science. 12, 12, and 7 unique variations in coloration of inflorescences were observed for I. lortetii, I. atrofusca, and I. haynei, respectively. The results indicate that the population size and the distribution range of the three Royal Irises are larger than previously reported, whereas the documented inflorescences’ coloration variations are unique and considerable. This study sheds light on hotspot occurrence sites of endangered and vulnerable species in Palestine, which can assist in laying adequate conservation actions and management plans in the future.

Half a century of spread: how trends can inform the phenology of Undaria pinnatifida in California.

The potential for non-native species to outcompete native species, change ecosystem dynamics and decrease biodiversity necessitates an understanding of their ecological role. Non-native seaweed species (NNSS) can be particularly impactful due to their cryptic life cycles, high fecundity, and tolerance to stressors which could allow rapid spread across coastlines. This literature review summarizes a few well known NNSS in California with a focus on using global literature on Undaria pinnatifida to inform potential trends of habitat use, dispersal, and phenology in this region. Globally, we found that Undaria is widely documented in bays and harbors but there are documented cases of it establishing populations in coastal habitats in exposed rocky reef ecosystems, including California. Using data on thermal tolerance for U. pinnatifida in its native range I found the sea surface temperatures (SST) throughout the west coast of the United States during 2019 are within the thermal tolerance of Undaria with the best SST for gametophytes occurring most frequently in southern California. Using data from the literature, I estimated the potential for Undaria to disperse from known populations in San Diego, CA. These data suggest that Undaria has the potential to disperse into open coastal habitats in this region. This study provides a case for further using pre-existing literature from other regions to guide research conducted in regions of interest that can inform management decisions.

Shrinking suitable habitat of a sub-Arctic foundation kelp under future climate scenarios.

Climate change has profound effects on the distribution of kelp forests in the Arctic and sub-Arctic. However, studies on the responses of kelps to climate change, particularly along the sub-Arctic regions of the Alaska coast, are limited. Eualaria fistulosa is a foundational kelp species in the Aleutian Islands, with an east-west distribution that extends from Japan to southern southwest Alaska. In this study, we utilized a species distribution model (SDM) to explore changes in the future habitat suitability of E. fistulosa under contrasting Shared Socioeconomic Pathway (SSP) scenarios. Our model exhibited relatively high predictive performance, validating our SDM predictions. Notably, the SDM results indicate that minimum sea surface temperature, annual range in sea surface temperatures, and annual mean current velocities are the three most important predictor variables determining E. fistulosa's distribution. Furthermore, the projected geographic distribution of Eualaria is generally consistent with its observed occurrence records. However, under high emission scenarios (SSP5-8.5), E. fistulosa is predicted to contract its distribution range by 9.0% by 2100, with widespread disappearance along the southeast Alaskan coast and limited northward migration to Kamchatka Krai in Russia and Bristol Bay in Alaska. These findings contribute valuable insights for conservation strategies via addressing climate-induced alterations in sub-Arctic kelp distribution.

An implicit solution for Asay foil trajectories generated by separable, sustained-production ejecta source models

We present a simple implicit solution for the time-dependent trajectory of a thin Asay foil ejecta diagnostic for the general case where the impinging ejecta cloud is generated by a source function characterized by an arbitrary (sustained) time dependence and a time-independent (stationary) particle velocity distribution. In the limit that the source function time dependence becomes a delta function, this solution—which is amenable to rapid numerical calculations of arbitrary accuracy—exactly recovers a previously published solution for the special case of instantaneous ejecta production. We also derive simple expressions for the free-surface arrival (catch-up) time as well as the true ejecta areal mass accumulation on the accelerating foil and place bounds on the level of error incurred when applying instant-production mass solutions to a sustained-production trajectory. We demonstrate these solutions with example calculations for hypothetical source functions spanning a wide range of ejecta production durations, velocity distributions, and temporal behaviors. These calculations demonstrate how the foil trajectory is often insensitive to the temporal dependence of the source function, instead being dominated by the velocity distribution. We quantify this insensitivity using a “compatibility score” metric. Under certain conditions, one may capitalize upon this insensitivity to obtain a good approximation of the second integral of the velocity distribution from the observed foil trajectory.

Mitochondrial markers revealed genetic panmixia in the data-deficient yellowfin snapper, Lutjanus xanthopinnis (Actinopterygii: Eupercaria: Lutjanidae), from a hotspot of the southern region of the South China Sea

Understanding the genetic structure and diversity of marine fish is crucial for a sustainable management program. We examined the genetic diversity and historical demographics of the yellowfin snapper, Lutjanus xanthopinnis Iwatsuki, Tanaka et Allen, 2015, in the coastal waters of east Peninsular Malaysia which is bordered by the southern part of the South China Sea using the mitochondrial genes (mtDNA) D-loop and Cytochrome b (Cyt-b). A total of 99 (D-loop) and 78 (Cyt-b) specimens of L. xanthopinnis were successfully sequenced from six locations within the range of species distribution along the Malaysian South China Sea. In the presently reported study, the lack of genetic differentiation among populations can be attributed to historical demographic events, eggs and planktonic larvae’ ability to disperse, spawning patterns, and the absence of physical barriers in the geographical landscape. Maximum likelihood gene trees demonstrated that the populations under study had limited structuring and formed a panmictic population that lacks support for internal clades. The AMOVA (Analysis of Molecular Variance) and population pairwise ФST values indicated high genetic exchange between the study areas. A high level of haplotype diversity (D-loop: 0.948–1.000; Cyt-b: 0.542–0.928), low nucleotide diversity (D-loop: 0.0095–0.0159; Cyt-b: 0.0022–0.0049) and starlike haplotype network indicates a recent expansion of L. xanthopinnis populations in Malaysian South China Sea. However, neutrality and goodness of fit tests revealed non-significant values. Furthermore, the BSP (Bayesian skyline plot) analysis estimated population expansion events during the late Pleistocene. During this epoch, the fluctuation in sea level may have led to an increase in the abundance of resources and favorable habitats for the yellowfin snapper. The presently reported findings could initiate efficient management strategies for L. xanthopinnis along the coastal areas of the Malaysian South China Sea and other nearby nations that share the same waterways.

A wide range of abiotic habitat factors and genetic diversity facilitate expansion of Trapa natans within its native range

Climate change and intense human activity are exacerbating changes in species' ranges. While the rapid spread of invasive alien species is well documented worldwide, the phenomenon of the spread of native species is poorly understood. To explain the problem of rapidly spreading species in the changing world, it is necessary to understand their ecology, genetic diversity and habitat limitation. The aim of our study was to analyze the ecological requirements and genetic diversity in the population of the macrophyte Trapa natans s. l., an invasive alien species in North America but native in Europe and Asia. We investigated the populations in its native range (Central and Northeastern Europe), where the species is defined as rare or extinct. We found the occurrence of T. natans in Northeastern Europe aquatic habitats where, up to now, it was described as an extinct species. The results of our environmental studies showed that the species has a wide range of tolerance to habitat conditions and lives in medium to highly nutrient-rich water with low and high salinity. Using Amplified Fragment Length Polymorphism (AFLP) analysis, we revealed high genetic variability within populations with relatively limited differentiation between populations. We showed that some populations are highly diverse (possibly refugia; Central Europe) and others are homogeneous (new sites, commercial reintroduction; Northeastern Europe). Conservation status of T. natans in its native range should be reconsidered, as the species has spread rapidly in recent decades and could be detrimental to aquatic habitats. The conclusion is that expansion/invasion can start from small populations, but under favorable conditions these populations spread rapidly. The introduction of species (even native) should be done carefully, if at all, as uncontrolled introduction to new locations, e.g. private ponds, could be the start of dispersal (native habitats) or invasion (non-native area).

PSLBII-5 Impacts of residual feed intake measured as a heifer in drylot on mature cows and calves grazing native pasture

Abstract Selection for feed efficiency is crucial for improving economic and environmental sustainability in beef cattle production. Residual feed intake (RFIfat) is a commonly used measure of feed efficiency and is determined in a drylot setting by calculating the difference between observed and expected dry matter intake (DMI), where expected feed intake is adjusted for metabolic body weight (BW), average daily gain (ADG) and body fatness. Lower RFIfat cattle are more efficient animals as they eat less than predicted for the same growth, body size and body fatness. Limited studies have been conducted evaluating the role of RFIfat on the subsequent performance of cow-calf pairs on native range. Kinsella Composite cows and calves (n = 120) grazed native pasture from July 11 to Sept 12 (summer) and from Sept 13 to Nov 2 (fall) of 2023 were included in this study. All dams had previously been evaluated for RFIfat as a heifer (8 to 12 mo of age) using the GrowSafe Feed Intake System (Vytelle, Canada). Cow and calf ADG were subjected to an analysis of covariance using lm function from stats R core package (R Core Team, 2024), with cow age (2 to 8 yr of age) as the fixed effect and RFIfat as the covariate, analyzing separately by season. An unbalanced Tukey HDS post-hoc were applied for age and p-values &amp;lt; 0.05 were considered significant. Weight gain was assessed on cows with an initial BW on pasture of 598.4 ± 68.4 kg, and 2 to 8 yr of age, and on calves having an initial on pasture BW of 106 ± 21.5 kg, and 65 ± 14 d of age. Cow age affected (P &amp;lt; 0.01) cow ADG during summer, with the youngest dams (2 yr old) gaining more weight than older animals (7 yr old; Figure 1A). No effect of RFIfat was found on cow weight gain during summer grazing. However, during fall grazing, RFIfat affected (P &amp;lt; 0.01) cow ADG (Figure 1B). Low-RFIfat cows (efficient) had increased weight gain during fall grazing as compared with high-RFIfat cows (inefficient: Figure 1B). Calf ADG was not affected (P &amp;gt; 0.1) by cow age, cow RFIfat and cow ADG during summer and fall. We conclude that cows with low RFIfat exhibited superior body weight gain, during fall grazing on native range when forage nutrient quality and quantity become limiting.

PSXI-2 Impact of flexible prepartum supplementation strategies on cow-calf and subsequent progeny feedlot performance

Abstract Implementation of minimal supplemental protein strategies during late gestation may have the potential to minimize any negative postweaning progeny performance while decreasing feed costs. A 3-yr study was conducted to evaluate the effects of mid- to late-gestation supplementation strategies on reproduction, cow body weight (BW), and calf performance in May-calving mature cows grazing upland native range. Cows received one of 3 supplementation strategies: 1) 0.227 kg/d of a 30% CP distillers-based supplement (HalfSupp), 2) 0.454 kg/d of a 30% CP distillers-based supplement (Supp), or 3) brief and intermittent supplementation of Supp at 0.454 kg/cow based on periods of acute environmental stress, such as snow cover, wet winter events, and is best described as flexible supplementation (Flex). Supplementation was initiated in December each year and terminated approximately 30-d prior to the start of the calving season in April. Across all 3 yr, average supplement feeding rate was 25.5, 50.9, and 5.4 kg/cow during the 112-d supplemental period, which resulted in average yearly prepartum supplemental costs of $27.30, 54.60, and 1.99 for HalfSupp, Supp, and Flex; respectively. After weaning, steers grazed sub-irrigated meadow with a dried distiller grain supplement until May. In May, all steers grazed sub-irrigated meadow without additional supplement until August/September when steers were shipped to West Central Research and Extension Center (WCREC). Steers were placed in a GrowSafe feeding system for the rest of the finishing feeding period. Each year, steers were slaughtered at a commercial facility (Tyson Fresh Meats, Lexington, NE) when estimated visually to have 1.3 cm fat thickness over the 12th rib as a group. Cow BW was not different (P = 0.86) at the initiation of supplementation in Jan. However, cows fed Half had a lighter (P &amp;lt; 0.01) BW at pre-calving and tended (P = 0.08) to have a lighter BW at pre-breeding than their counterparts. After a 45-d breeding season, pregnancy rates were not influenced (P = 0.91) by prepartum supplementation strategies. Prepartum supplementation strategies did not influence (P &amp;gt; 0.56) preweaning calf BW at birth, pre-breeding, and weaning. In addition, steer backgrounding BW was also not influenced (P &amp;gt; 0.63) by prepartum supplementation strategy of their dam. Upon entry into the feedlot, steer BW was not impacted (P &amp;gt; 0.84) by prepartum supplementation strategy of their dam. Feedlot performance (BW, average daily gain, and feed efficiency) was not influenced (P &amp;gt; 0.59) by prepartum supplementation strategy of their dam. After harvest, all carcass characteristics were not impacted (P &amp;gt; 0.11) by the prepartum supplementation strategy of the dam. Considering the cost for prepartum supplementation, feeding a protein supplement just during environmentally stressful periods during gestation appears to be a viable alternative to more conventional methods and reduces winter feed costs.

Investigation of local mechanical behavior during the shear process of rough rock joints using DEM

Rough joints are prevalent in natural rock masses, and their shear mechanical properties are crucial for ensuring the safety and stability of these masses. Existing studies often neglect the contribution of various joint asperities to shear stress resistance. This study addresses this gap by eluci-dating the local shear mechanisms of different asperities in rough joints throughout the shear process. This was achieved through a combination of quantitative and qualitative analyses using the Discrete Element Method (DEM). Initially, Barton's ten standard roughness joint profiles were dig-itized, and rough joints were modeled using the Modified Smooth Joint Model (MSJM). Direct shear tests on joint specimens under constant nor-mal stress were performed using servo-controlled methods. Subsequently, the shear stress behavior was analyzed in relation to the test results. The failure modes of the joint specimens were examined in detail using crack tracking and force chain analysis. The study also explored the relation-ship between the number of cracks and shear stress. Additionally, variations in average stress across ten different segments of joints during shear were monitored using the measuring circle function. The shear resistance contributions of local joint segments were quantitatively assessed using three stress indices: maximum stress, upper limit of maximum stress, and the distribution range of maximum stress. The Joint Roughness Coeffi-cient (JRC) of joints was found to correlate well with these indices. Overall, the progressive failure of local joint segments was analyzed both qual-itatively and quantitatively. The study confirmed that the local shear mechanisms of different joint segments during the shear process are distinct.

Perilous state of critically endangered Northwest African cheetah (Acinonyx jubatus hecki) across the Sudano‐Sahel

AbstractNorthwest African cheetah populations have declined precipitously, with expert opinion estimating that &lt;420 individuals persist across parts of Algeria, Benin, Burkina Faso, Chad, Niger and Mali. However, no reliable density estimates exist in the remaining subspecies strongholds throughout the Sudano‐Sahel Zone, including the W‐Arly‐Pendjari Complex and Greater Zakouma Ecosystem within the Bahr/Salamat landscape. Camera trap surveys were combined with spatially explicit capture–recapture methodologies in both regions to estimate the cheetah density and detectable demographic composition of these populations. Following 15 429 camera trap nights, we detected nine individuals during the dry season and four individuals during the wet season in Pendjari (2021), nine individuals (dry season; 2023) in Zakouma and none in Siniaka Minia. Cheetah densities were thus estimated at 0.17–0.24 and 0.37 cheetah per 100 km2 in Pendjari and Zakouma, respectively. While marginally higher than predicted, such low‐density estimates are concerning in the last remaining habitats harbouring this critically endangered subspecies. Considering the substantial contraction of regional cheetah distribution, we estimate an overall population size of 68 ± 29 individuals across the studied areas. These novel estimates are among the lowest formally determined densities throughout cheetah range in Africa, where a high frequency of people and livestock detected on camera traps highlight the ongoing risks to large carnivores in these protected areas. Subsequent management recommendations include implementation of the established regional conservation strategies that encompass the distributional range of these cheetah, continuous monitoring of populations, genetic analyses to inform management, curbing illegal trade and increasing international awareness around the plight of the subspecies.

Climate covariate selection influences MaxEnt model predictions and predictive accuracy under current and future climates

The performance and transferability of species distribution models (SDMs) depends on a number of ecological, biological, and methodological factors. There is a growing body of literature that explores how the choice of climate covariate combinations and model parameters can affect predictive performance, but relatively few that delve into covariate reduction methods and the optimisation of model parameters, and the resulting spatial and temporal transferability of those models. The present work used the citrus pest, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), to illustrate how MaxEnt models trained on the insect’s native range in Asia varied in their predictions of climatic suitability across the introduced range when eight different covariate reduction methods were applied during model building. Additionally, it showed how model sensitivity varied across these different covariate combinations using three sets of independently validated occurrence points in the invaded range of the psyllid. Climatically suitable areas for D. citri differed by as much as two-fold between the best and worst-performing models in selected areas. Great care should be taken in the selection of the highest-performing predictor combinations and model parameter settings for SDMs, particularly in the case of invasive species where the assumption of environmental equilibrium is likely violated in the introduced range. Understanding how the predictive ability of SDMs can be influenced by the methodological choices made during the model building phase is vital to ensuring that ecological and invasion management programmes do not over- or underestimate climatic suitability and subsequent invasion risk.

185 Effect of synchronized fixed-time AI and non-pregnant heifer delayed feedlot entry on reproductive performance and system economics

Abstract Heifer reproduction management research is being conducted at the NDSU–Dickinson Research Extension Center. Using crossbred heifers, the objective was to evaluate reproductive performance and economic efficiencies comparing a drylot synchronized fixed-time AI protocol with clean-up bulls to two grazing systems using a fixed-time AI protocol without clean-up bulls. Synchronization protocol:14-d CIDR-PG-GnRH (TAI 66 h ± 2 h). Fixed-time AI treatments: 1) Drylot Control (DLOT) with clean-up bulls, 2) Integrated diverse crop-heifer annual forage grazing (IAF, no clean-up bulls), and 3) Native range grazing (NR, no clean-up bulls). Following pregnancy ultrasound on d 85, non-pregnant heifers continued to bale-graze until late November, when they were transferred to the University of Wyoming SAREC feedlot, finished, harvested at Cargill Meat Solutions packing plant, Ft. Morgan, CO, and grid marketed. Data were analyzed using the MIXED procedure of SAS. Year 1 and 2 grazing days were 121, and 149, respectively. Synchronized TAI pregnancy rates yr 1 and 2 for DLOT, IAF, and NR were 59.4, 43.8, and 62.5%; 68.8, 46.9, and 34.4%, respectively. Total DLOT control pregnancy rates yr 1 and 2 were 90.6 and 100%. Grazing heifer feedlot performance Yr 1 did not differ for starting body weight (BW; 452 vs 436 kg, P = 0.29), ending BW (610 vs 600 kg, P = 0.74), gain (157 vs 164 kg, P = 0.69), average daily gain (ADG; 1.42 vs 1.48 kg, P = 0.70), dry matter (DM) feed intake (15.0 vs 14.7 kg, P = 0.73), F:G (4.81 vs 4.56 kg, P = 0.42), daily feed cost ($7.45 vs $9.47, P = 0.73), feed cost/kg BW gain ($3.11 vs $2.95, P = 0.51), and feed and yardage cost ($3.41 vs $3.24, P = 0.55). Year 2 grazing heifer feedlot performance for the IAF and NR were starting BW (501 vs 456 kg, P = 0.007), ending BW (670 vs 604 kg, P = 0.004), feedlot finishing gain (143 vs 123 kg, P = 0.05), ADG (1.08 vs 0.93 kg/day, P = 0.06), daily DM feed intake (20.1 vs 20.1 kg/d, P = 0.98), feed to gain ratio (7.13 vs 8.22 kg/d, P = 0.11), daily feed cost ($9.61 vs $9.54/d, P = 0.94), feed cost/kg BW gain ($4.05 vs $4.67/kg, P = 0.11), and feed and yardage cost/kg gain ($4.45 vs $5.13/kg, P = 0.092). IAF and NR Yr 1 HCW (P = 0.83), dressing % (P = 0.69), marbling score (P = 0.78) did not differ. Year 2, except for hot carcass weight (HCW; 379 vs 341 kg, P = 0.004), dressing pct (P = 0.99), fat depth (P = 0.29), marbling score (P = 0.94) did not differ. Systems 2-yr mean net return for DLOT, IAF, and NR were $592, $296, $379, respectively. Systems net return profitability was very good for all management comparisons, but reduced for IAF and NR due to IAF farming, finishing, and transportation costs, and NR finishing and transportation costs.

Is the typical stage of Penicillus capitatus Lamarck (Bryopsidales, Halimedaceae) a possible indicator of climate warming?

In this study, through morphological and molecular analysis approaches, we documented the presence of the typical stage (adult stage) of Penicillus capitatus during the coldest seasons of the year, typically periods when this form had never been reported in the Mediterranean. Indeed, the typical stage is common throughout the year in the western Atlantic (native range of the species), whereas it is rare in the Mediterranean, where the Espera stage (juvenile stage) is the main stage. To date, in the Mediterranean, the adult stage has been found only in the warmer months of the year. Therefore, the observation of the typical stage in the Mediterranean Sea during the cold season might suggest a general increase in the seawater temperature in this basin, rendering this stage of P. capitatus a potential climate bioindicator. Furthermore, owing to the molecular analysis methods adopted, it was possible to assess the relationships between the Mediterranean and Atlantic populations of this species.

Thermal stress during incubation in an arctic breeding seabird

Arctic breeding seabirds have experienced dramatic population declines in recent decades. The population of Arctic skuas (Stercorarius parasiticus) nesting on the Faroe Islands, North Atlantic, breed near the southern extent of their breeding range and are experiencing some of the largest declines. This is thought to be caused in part by increased warming due to climate change and thus, it is becoming critical to investigate the proximate and ultimate effects of the thermal environment on parental physiology, behaviour and breeding success. Behavioural observations at an Arctic skua long-term monitoring colony were undertaken during the 2016 breeding season to determine the frequencies of thermoregulatory panting, and interrupted incubation events. Incubating Arctic skuas showed thermoregulatory behaviour at air temperatures (Ta) of 9 °C, which suggested that they may be operating near their upper thermal tolerance limit. Arctic skuas spent significantly more time panting as Ta increases, wind speed decreases and sun exposure increases. This relationship was apparent even within the narrow ranges of Ta (7.5–15 °C) and wind speed (0-5 ms−1) recorded. Incubation effort was not continuous with birds leaving the nest for up to 100% of the observation block. While we found no relationship between interrupted incubation and environmental conditions, panting was only observed in birds that were simultaneously incubating eggs. These results highlight the constraints on birds during the incubation phase of breeding, and indicate a potential maladaptive behaviour of maintaining incubation despite the increased cost of thermoregulation under warming temperatures in this species. However, the relationship between thermal stress, nest absence and demographic parameters remains unclear, highlighting the importance of longitudinal and/or high-resolution studies that focus on Arctic specialists and the interrelationships between environmental factors, nest absence rates and productivity.