Multi-level societies are complex social systems where basic core units associate in a hierarchical manner, allowing animals to adjust group size in response to local conditions. Each tier of multi-level societies may have evolved under different selective pressures and understanding the effect of temporal variation in these pressures may help determine why these types of social systems form. Our goal was to examine the degree of temporal variability in inter-unit associations in a multi-level society of Rwenzori Angolan colobus monkey (Colobus angolensis ruwenzorii), and to determine whether social or ecological factors correlated with association patterns. Using social network analyses, we described the association patterns of 12-13 core units over 21-months and investigated the effect of changes in rainfall, food availability, and inter-unit dispersals. We found that core unit networks were denser and more clustered when fruit was abundant, likely due to reduced food competition. Male dispersals also occurred more at these times, suggesting that greater band cohesion allowed males to prospect for dispersal opportunities. Within the band, we observed the formation of an all-male unit and the transfer of one core unit between clans. Our findings highlight how ecological conditions can influence association patterns, interunit relationships, and ultimately social organization.
Meta-analyses often encounter studies with incompletely reported variance measures (e.g. standard deviation values) or sample sizes, both needed to conduct weighted meta-analyses. Here, we first present a systematic literature survey on the frequency and treatment of missing data in published ecological meta-analyses showing that the majority of meta-analyses encountered incompletely reported studies. We then simulated meta-analysis data sets to investigate the performance of 14 options to treat or impute missing SDs and/or SSs. Performance was thereby assessed using results from fully informed weighted analyses on (hypothetically) complete data sets. We show that the omission of incompletely reported studies is not a viable solution. Unweighted and sample size-based variance approximation can yield unbiased grand means if effect sizes are independent of their corresponding SDs and SSs. The performance of different imputation methods depends on the structure of the meta-analysis data set, especially in the case of correlated effect sizes and standard deviations or sample sizes. In a best-case scenario, which assumes that SDs and/or SSs are both missing at random and are unrelated to effect sizes, our simulations show that the imputation of up to 90% of missing data still yields grand means and confidence intervals that are similar to those obtained with fully informed weighted analyses. We conclude that multiple imputation of missing variance measures and sample sizes could help overcome the problem of incompletely reported primary studies, not only in the field of ecological meta-analyses. Still, caution must be exercised in consideration of potential correlations and pattern of missingness.
Several studies have attempted to understand the origin and evolution of single exon genes (SEGs) in eukaryotic organisms including fishes, but few have examined the functional and evolutionary relationships between SEG and multiple exon gene (MEG) orthologs, in particular the conservation of promoter regions. Given that SEGs originate via the reverse transcription of mRNA from a “parental” MEG, such comparisons may enable identifying evolutionarily-related SEG/MEG orthologs, which might fulfill equivalent physiological functions. Here, the relationship of SEG proportion with MEG count, gene density, intron count and chromosome size was assessed for the genome of sea bass, Dicentrarchus labrax. Then, SEGs with an MEG parent were identified, and promoter sequences of SEG/MEG orthologs compared, to identify highly conserved functional motifs. The results revealed a total proportion of 1585 (8.3%) SEGs evenly distributed in the sea bass genome, which was correlated with MEG count but not with gene density. These results suggest that SEGs are continuously and independently generated after species divergence over evolutionary time, as is evident from the significant proportion of SEGs with an MEG parent. Functional annotation showed that the majority of SEGs are functional, as is evident from their expression in RNA-seq data used to support homology-based genome annotation. Differences in 5’UTR and 3’UTR lengths between SEG/MEG orthologs observed in this study may contribute to gene expression divergence between them, and therefore lead to the emergence of new SEG functions. The comparison of nonsynonymous to synonymous changes (Ka/Ks) between SEG/MEG parents showed that 74 of them are under positive selection (Ka/Ks > 1; P = 0.0447). An additional fifteen of SEGs with a MEG parent have a common promoter, which implies that they are under the influence of common regulatory networks and may be involved in equivalent functions.
We conducted a comprehensive analysis of the phylogenetic, phylogeographic, and demographic relationships of Caspian cobra (Naja oxiana; Eichwald, 1831) populations based on a concatenated dataset of two mtDNA genes (cyt b and ND4) across the species’ range in Iran, Afghanistan, and Turkmenistan, along with other members of Asian cobras (i.e. subgenus Naja Laurenti, 1768). Our results provided strong support that N. oxiana is monophyletic and its divergence from its sister taxon, N. kaouthia, during early Pleistocene. Our results also highlight the existence of only one major evolutionary lineage in the Trans-Caspian region, suggesting a rapid expansion of the Caspian cobra from eastern to western Asia, coupled with a rapid range expansion from east of Iran to the northeast. However, the subdivision of eastern and northeastern populations in Iran was not supported; hence we propose only one evolutionary significant unit across the Iranian range of N. oxiana to be considered for conservation efforts.
In boreal landscapes, emphasis is currently placed on close-to-nature management strategies, which aim to maintain the biodiversity and ecosystem services related to old-growth forests. The success of these strategies, however, depends on an accurate understanding of the dynamics within these forests. This study aims to reconstruct the disturbance and post-disturbance dynamics in boreal old-growth forests that are driven by recurrent moderate-severity disturbances. We studied eight old-growth forests in Québec, Canada, that has recorded recurrent and moderate to severe spruce budworm (Choristoneura fumiferana [Clem.]) outbreaks over the 20th century. To reconstruct the disturbance history and the post-disturbance dynamics of the study sites, we used dendrochronological data and k-means clustering to identify growth releases and growth patterns in the studied trees. We identified nine growth patterns; these patterns represented trees differing in age, size, and canopy layer, and indicated different tree histories. Spruce budworm outbreaks caused recurrent moderate-severity disturbances within the study sites. The canopy gaps created by these disturbances were filled mainly by understorey trees, which responded by single and significant increases in radial growth and height. In contrast, overstorey trees had little influence on gap filling; thus, trees were mostly from the dominant and codominant canopy layers. Our study underlines the resistance of boreal old-growth forests to recurrent and moderate-severity disturbances, as understorey trees can rapidly fill the resulting gaps. However, trees that are unable to attain the canopy following the disturbance then tend to remain in the lower canopy layers. Therefore, reaching the canopy represents a once-in-a-lifetime opportunity, where success or failure depends on a relatively short window of time. This gap-filling dynamic produces, however, a vertical structure that is often similar to the expected structure in even-aged forests. Our results highlight the efficacy of identifying tree growth patterns to reconstruct stand disturbance dynamics and contribute to developing closer to nature forest management strategies.
The diversity of butterflies is known to some extent in Nepal, but the study of their interactions with nectar plant sources and floral attributes is limited. This study was conducted along the periphery of Rupa Wetland, a Ramsar site, from February to November 2019 to assess butterfly species diversity and to identify the factors influencing their foraging choices at nectar plants. We assessed the number of butterfly species, their abundance, and their floral foraging behavior, from 28 linear transects (500 m long each) placed in a stratified and random manner throughout the study area. Five factors, i.e., category of plant, flower colour, corolla shape, corolla depth, and the proboscis length of butterfly species were taken into account to assess the nectar plant choices of butterfly families. Moreover, species diversity at the family level, and overall, were determined through several indices. When examining overall butterfly diversity and abundance, we recorded a total of 1,535 butterflies belonging to 138 species within six families. For our examination of butterfly-nectar plant observations, we recorded a total of 298 individuals belonging to 31 species of butterfly visiting a total of 28 nectar plant species. Among the recorded butterflies, Zemeros flegyas was found to be the most abundant (92 individuals), while only a single individual each of the species Troides helena, Gandaca herina and Belonois aurota were recorded. Of the 28 nectar host plant species, Biden pilosa was the most popular and was visited by 13 species of butterflies. Overall, total butterfly visitation was found to be significantly influenced by plant category (herbaceous preferred over woody), floral colour (yellow, white, and purple preferred over pink), and corolla shape (tubular preferred over non-tubular). Moreover, there was a significant positive correlation (r = 0.466) between the proboscis length of butterflies and the corolla tube length of flowers (p<0.001).
The geographical origin of watermelon (Citrullus lanatus) remains debated. While a first hypothesis suggests the center of origin to be west Africa, where a sister endemic species C. mucosospermus thrives, a second hypothesis suggests north-eastern Africa where the white-fleshed Sudanese Kordophan melon is cultivated. In this study, we infer biogeographical and haplotype genealogy for C. lanatus, C. mucosospermus, C. amarus, and C. colocynthis using non-coding cpDNA sequences (trnT-trnL and ndhF-rpl32 regions) from a global collection of 135 accessions. In total, we identified 38 haplotypes in C. lanatus, C. mucosospermus, C. amarus, and C. colocynthis; of these, 21 were found in Africa and 17 appear endemic to the continent. The least diverse species was C. mucosospermus (5 haplotypes) and the most diverse was C. colocynthis (16 haplotypes). Some haplotypes of C. mucosospermus were nearly exclusive to West-Africa, and C. lanatus and C. mucosospermus shared haplotypes that were distinct from those of both C. amarus and C. colocynthis. The results support previous findings C. mucosospermus to be the closest relative to C. lanatus (including subsp. cordophanus). West Africa, as a center of endemism of C. mucosospermus, is an area of interest in the search of the origin of C. lanatus. This calls for further historical and phylogeographical investigations and wider collection of samples in West and North-East Africa.
Na+ and Cl– are the most abundant dissolved ions in seawater, constituting ~85% of total ions. They significantly affect the osmolality of body fluids of marine invertebrates. Seawater also contains minor ions such as Mg2+, Ca2+, K+, and SO42–, but their effects on marine organisms are unclear. This study analyzed the effects of Mg2+, Ca2+, and K+ (ambient minor cations) on survival, hemolymph ionic composition, and gene expression in the gills of three euryhaline crabs: Helice tridens, Macrophthalmus japonicus, and Chiromantes dehaani. Ambient minor cations were required for survival of H. tridens and M. japonicus under isosmotic conditions with seawater. The ambient minor cations also affected the osmolality and ionic composition of hemolymph by regulating expressions of specific genes in the gills required for Na+ uptake, such as Na+/K+ ATPase, cytoplasmic carbonic anhydrase, and Na+/H+ exchanger. Administration of carbonic anhydrase and Na+/H+ exchanger inhibitors increased the survival rate even if ambient minor cations did not exist. In contrast, under hypo-osmotic conditions, ambient minor cations had different effects on crabs; a lethal effect on M. japonicus, and an increase of the hemolymph K+ concentration in H. tridens and M. japonicus. It is thus concluded that the effects of ambient minor cations are osmolality–dependent. In contrast, in C. dehaani, the hemolymph ionic composition and survival rate were hardly affected by ambient minor cations, probably reflecting the habitat of this species. These results strongly indicated that C. dehaani is less susceptive to ambient minor cations compared to H. tridens and M. japonicus.
1. The metric of functional evenness FEve is an example of how approaches to conceptualizing and measuring functional variability may go astray. 2. The index of functional evenness FEve has critical conceptual and practical drawbacks: a) Different values of the FEve index for the same community can be obtained if the species have unequal species abundances; this result is highly likely if most of the traits are categorical. b) Very minor differences in even one pairwise distance can result in very different values of FEve. c) FEve uses only a fraction of the information contained in the matrix of species distances. Counterintuitively, this can cause very similar FEve scores for communities with substantially different patterns of species dispersal in trait space. d) FEve is a valid metric only if all species have exactly the same abundances. However, the meaning of FEve in such an instance is unclear as the purpose of the metric is to measure the variability of abundances in trait space. 3. We recommend not using FEve metric in studies of functional variability. Given the wide usage of FEve index over the last decade, the validity of the conclusions based on those estimates are in question. 4. Instead, we suggest three alternative metrics that combines variability in species distances in trait space with abundance in various ways, and more broadly recommend that researchers think about which community properties (e.g., trait-distances of a focus species to the nearest neighbor or all other species, variability of pairwise interactions between species) they want to measure and pick from among the appropriate metrics.
Ambrosia artemisiifolia and Ambrosia trifida are two species of very harmful and invasive plants of the same genus. However, it remains unclear why A. artemisiifolia is more widely distributed than A. trifida worldwide. Distribution and abundance of these two species were surveyed and measured from 2010 to 2017 in the Yili Valley, Xinjiang, China. Soil temperature and humidity, main companion species, the biological characteristics in farmland ecotone, residential area, roadside and grassland, and water demand of the two species were determined and studied from 2017 to 2018. The area occupied by A. artemisiifolia in the Yili Valley was more extensive than that of A. trifida, while the abundance of A. artemisiifolia in grassland was less than that of A. trifida at eight years after invasion. The interspecific competitive ability of two species were stronger than those of companion species in farmland ecotone, residential, and roadside. In addition, A. trifida had greater interspecific competitive ability than other plant species in grassland. The seed size and seed weight of A. trifida were five times or eight times those of A.artemisiifolia. When comparing the changes under simulated annual precipitation of 840 mm versus 280 mm, the seed yield per m2 of A. trifida decreased from 50,185 to 19, while that of A. artemisiifolia decreased from 15,579 to 530. The differences in the distribution of the two species are mainly due to differences in interspecific competitive ability, seed size, and water dependence. The two species have stronger interspecific competitive ability than that of companion species, but A. artemisiifolia has a smaller seed size and stronger drought tolerance, which allows A. artemisiifolia to spread farther than A. trifida. The reason for wider distribution of A. trifida in grassland is that A. trifida has stronger interspecific competitive ability than A. artemisiifolia under sufficient water.
Tree spatial patterns in dry coniferous forests of the western US, and analogous ecosystems globally, were historically aggregated, comprising a mixture of single trees and groups of trees. Modern forests, in contrast, are generally more homogeneous and overstocked than their historical counterparts. As these modern forests lack regular fire, pattern formation and maintenance is generally attributed to fire. Accordingly, fires in modern forests may not yield historically analogous patterns. However, direct observations on how selective tree mortality among pre-existing forest structure shapes tree spatial patterns is limited. In this study, we (1) simulated fires in historical and contemporary counterpart plots in a Sierra Nevadan mixed-conifer forest, (2) estimated tree mortality, and (3) examined tree spatial patterns of live trees before and after fire, and of fire-killed trees. Tree mortality in the historical period was clustered and density-dependent, because trees were aggregated and segregated by tree size before fire. Thus, fires maintained an aggregated distribution of tree groups. Tree mortality in the contemporary period was widespread, except for dispersed large trees, because most trees were a part of large, interconnected tree groups. Thus, post-fire tree patterns were more uniform and devoid of moderately sized tree groups. Post-fire tree patterns in the historical period, unlike the contemporary period, were within the historical range of variability identified for the western US. This divergence suggests that decades of forest dynamics without significant disturbances has altered the historical means of pyric pattern formation. Our results suggest that ecological silvicultural treatments, such as forest restoration thinnings, which emulate qualities of historical forests may facilitate the reintroduction of fire as a means to reinforce forest structural heterogeneity.
Implementation of effective conservation planning relies on a robust understanding of the spatio-temporal distribution of the target species. In the marine realm, this is even more challenging for species rarely seen at the sea surface due to their extreme diving behaviour like the sperm whales. Our study aims at (i) investigating the seasonal movements, (ii) predicting the potential distribution and (iii) assessing the diel vertical behaviour of this species in the Mascarene Archipelago in the Southwest Indian Ocean. Using 21 satellite tracks of sperm whales and 8 environmental predictors, 14 supervised machine learning algorithms were tested and compared to predict the whales’ potential distribution during the wet and dry season, separately. Fourteen of the whales remained in close proximity to Mauritius while a migratory pattern was evidenced with a synchronized departure for 8 females that headed towards Rodrigues Island. The best performing algorithm was the random forest, showing a strong affinity of the whales for Sea Surface Height during the wet season and for bottom temperature during the dry season. A more dispersed distribution was predicted during the wet season whereas a more restricted distribution to Mauritius and Reunion waters was found during the dry season, probably related to the breeding period. A diel pattern was observed in the diving behaviour, likely following the vertical migrations of squids. The results of our study fill a knowledge gap regarding seasonal movements and habitat affinities of this vulnerable species, for which aregional IUCN assessment are still missing in the Indian Ocean. Our findings also confirm the great potential of machine learning algorithms in conservation planning and provide highly reproductible tools to support dynamic ocean management.
The coronavirus disease 2019 (COVID-19) pandemic introduced an abrupt change in human behavior globally. Here, we discuss unique insights into the eco-evolutionary role of pathogens in ecosystems and present data that indicates the pandemic can fundamentally change our learning choices. This pathogen has indirectly affected many organisms and processes by globally changing the behavior of humans to avoid being infected. The pandemic also changed our learning behavior by affecting the relative importance of information and forcing teaching and learning into a framework that accommodates human behavioral measures to avoid disease transmission. Not only are these indirect effects on the environment occurring through a unique mechanistic pathway in ecology, the pandemic along with its effects on us provides a profound example of the role risk can play in the transmission of information between the at-risk. Ultimately, these changes in our learning behavior led to this special issue “Taking learning online in Ecology and Evolution.” The special issue was a call to the community to take learning in new directions, including online and distributed experiences. The topics examined include a significant component of DIY ecology and evolution that is experiential and but done individually, opportunities to use online tools and apps to be more inclusive, student-focused strategies for teaching online, how to reinvent conferences, strategies to retain experiential learning safely, emerging forms of teaching such as citizen science, apps and podcasting, and ideas on how to accommodate ever changing constraints in the college classroom, to name a few. The collective consensus in our fields is that these times are challenging but we can continue to improve and innovate on existing developments, and more broadly and importantly, this situation may provide an opportunity to reset some of the existing practices that fail to promote an effective and inclusive learning environment.
Complex biological traits often originate by integrating previously separate parts, but the organismal functions of these precursors are challenging to infer. If we can understand the ancestral functions of these precursors, it could help explain how they persisted and how they facilitated the origins of complex traits. Animal eyes are some of the best studied complex traits, and they include many parts, such as opsin-based photoreceptor cells, pigment cells, and lens cells. Eye evolution is understood through conceptual models that argue these parts gradually came together to support increasingly sophisticated visual functions. Despite the well accepted logic of these conceptual models, explicit comparative studies to identify organismal functions of eye-precursors are lacking. Here, we investigate how precursors functioned before they became part of eyes in Cnidaria, a group formed by sea anemones, corals and jellyfish. Specifically, we test whether ancestral photoreceptor cells regulated the discharge of cnidocytes, the expensive single-use cells with various uses including prey capture, locomotion, and protection. Similar to a previous study of Hydra, we show an additional four distantly related cnidarian groups discharge significantly more cnidocytes when exposed to dim blue light compared to bright blue light. Our comparative analyses support the hypothesis that the cnidarian ancestor was capable of modulating cnidocyte discharge with light. Although eye-precursors might have had other functions like regulating timing of spawning, our findings are consistent with the hypothesis that photoreceptor cells which mediate cnidocyte discharge predated eyes, perhaps facilitating the prolific origination of eyes in Cnidaria.
Polyandry, when females mate with more than one male, is theorised to play an important role in successful colonisation of new habitats. In addition to possible benefits from sexual selection, even mild polyandry could facilitate colonisation by protecting against inbreeding and reducing the costs of mating with incompatible or infertile males. Here, we measure the importance of mild polyandry for population viability and reproductive fitness following experimental founder events into a higher temperature regime. Using colonisation experiments with the model beetle Tribolium castaneum, in which females can produce offspring for up to 140 days following a single mating, we founded more than 100 replicate populations using single females that had been given the opportunity to mate with either one or two males, and then tracked their subsequent population dynamics. Following population viability and fitness across ten generations, we found that extinction rates were significantly lower in populations founded by females given polyandrous opportunities to mate with two males (9%) compared to populations founded by monogamous females (34%). In addition, populations founded by females that had been provided with opportunities to store sperm from two different males showed double the median productivity following colonisation compared to monogamous-founded populations. Notably, we identified short-term and longer-term benefits to post-colonisation populations from double-mating, with results suggesting that polyandry acts to both protect against mating with incompatible males through the founder event, and reduce inbreeding depression as the colonisation proceeds for ten generations. Our results therefore show that even mild polyandry provides both reproductive and genetic benefits for colonising populations.
In a polymorphic species, stable differences in resource use are expected among ecotypes, and homogeneity in resource use is predicted within an ecotype. Yet, using a broad resource spectrum has been identified as a strategy for fishes living in unproductive northern environments, where food is patchily distributed and ephemeral. We investigated whether individual specialization of trophic resources occurred within the generalist piscivore ecotype of lake trout from Great Bear Lake, Canada, reflective of a form of diversity. Four distinct dietary patterns of resource use within the lake trout ecotype were detected from fatty acid composition, with some variation linked to spatial patterns within Great Bear Lake. Feeding habits of different groups within the ecotype were not associated with detectable morphological or genetic differentiation, suggesting that behavioral plasticity caused the trophic differences. A low level of genetic differentiation was detected between exceptionally large-sized individuals and other individuals. Investigating a geologically young system that displays high levels of intraspecific diversity and focusing on individual variation in diet suggested that individual trophic specialization can occur within an ecotype. The characterization of niche use among individuals, as done in this study, is necessary to understand the role that individual variation can play at the beginning of differentiation processes.
Plasticity in salt tolerance can be crucial for successful biological invasions of novel habitats by marine gastropods. The intertidal snail Batillaria attramentaria, which is native to East Asia but invaded the western shores of North America from Japan eighty years ago, provides an opportunity to examine how environmental salinity may shape behavioral and morphological traits. In this study, we compared the movement distance of four B. attramentaria populations from native (Korea and Japan) and introduced (USA) habitats under various salinity levels (13, 23, 33, and 43 PSU) during 30 days of exposure in the lab. We sequenced a partial mitochondrial CO1 gene to infer phylogenetic relationships among populations and confirmed two divergent mitochondrial lineages constituting our sample sets. Using a statistic model-selection approach, we investigated the effects of geographic distribution and genetic composition on locomotor performance in response to salt stress. Snails exposed to acute low salinity (13 PSU) reduced their locomotion and were unable to perform at their normal level (the moving pace of snails exposed to 33 PSU). We did not detect any meaningful differences in locomotor response to salt stress between the two genetic lineages or between the native snails (Japan versus Korea populations), but we found significant locomotor differences between the native and introduced groups (Japan or Korea versus the USA). We suggest that the greater magnitude of tidal salinity fluctuation at the USA location may have influenced locomotor responses to salt stress in introduced snails.
1.Large carnivore conservation is complex and remains a massive challenge across the world. Owing to their wide-ranging habits, large carnivores encounter various anthropogenic pressures which may potentially lead to conflict. Animal movement is linked with individual fitness as it is important for various biological processes. Therefore, studying how large carnivores adapt their movement to dynamic landscape conditions is vital for management and conservation policy. 2.We first quantified the movement parameters of four large carnivores in and outside protected-areas in India (tiger, leopard, dhole and wolf). We then tested the effects of human pressures like human density, road density and land use types on the movement of the species. Finally, we examined the configuration of core areas as a strategy to exploit human-dominated landscape. 3.Our findings suggest that the mean hourly displacement of 4 large carnivores differed across habitats. Mean displacement of large carnivores varied from 77.58m/h for leopards to 665.3m/h for wolves. Tigers outside PAs exhibited higher displacement as compared to tigers inside PAs. Displacement during day and night were significantly different for tigers inside and outside PAs (P=0.03), and wolf whereas no difference was found for leopard and dholes. The movement and ranging patterns of species outside PAs were influenced by anthropogenic factors such as human population, road network density, and landuse. All carnivores showed multiple areas of intensive use or cores in their home ranges. The range of the core area sizes was greater for species outside PAs (tiger and wolf) in human-altered landscapes. 4.Movement ecology of large carnivores has not been explored using such an exhaustive dataset in India. Our study attempts to extend theoretical concepts to applied management problems. This study can be a starting point for rigorous studies on interlinking animal movement and landscape management for large carnivore conservation and policy-making in the Anthropocene.