Carnivore coexistence without competition: giant otters are more nocturnal around dens than sympatric neotropical otters.

Nocturnal activity of tropical otters is rarely reported. To date no studies have documented den use by sympatric giant (Pteronura brasiliensis) and neotropical otters (Lontra longicaudis). We used camera-traps to monitor den use by sympatric otters along an equatorial Amazonian river. Camera-traps provided evidence that giant otters were more nocturnal around dens than sympatric neotropical otters. Nocturnal activity was recorded in 11% of giant otter photos (n = 14 of 125 photos), but was recorded only once for neotropical otters. Den use by giant and neotropical otters overlapped spatially and temporally but not concurrently. We hypothesize that previously reported nocturnal activity in neotropical otters is facilitated by the absence or low density of giant otters. Our results also underscore the need to use complementary techniques together with den counts for monitoring otters as sympatric species can use the same dens.

Dolphin and porpoise detections by the F-POD are not independent: Implications for sympatric species monitoring.

The F-POD is designed for passive acoustic monitoring of odontocetes. The offline classifiers can identify and separate porpoise-like sounds from dolphin-like sounds. We show that these two classifiers are not working independently. Run together, virtually no detections of both species were reported within the same minute, whereas 10% of the detection positive minutes were reported positive for both species when the two classifiers were run sequentially. This has important implications for interpretation of data in areas containing both species groups, and we call for reporting all analysis details in such studies and for further description and analysis of the classifiers.

Survey of ectoparasites affecting dog and cat populations living in sympatry in Gamo Zone, Southern Ethiopia.

BACKGROUND: Ectoparasites of dogs and cats are implicated to be responsible for life-threatening anaemia, allergic dermatitis and pruritic and non-pruritic skin disorders. In Ethiopia, few studies have been conducted on the arthropods of dogs and cats. OBJECTIVES: In order to shed light on some of these aspects, a survey was conducted to investigate the presence of ectoparasites in dogs and cats living in sympatry in the urban and rural areas of Gamo Zone, Ethiopia. METHODS: A total of 297 dogs and 110 cats were examined for ectoparasites, and questionnaires were employed to obtain information concerning owner's knowledge about arthropods and vector-borne diseases (VBDs). RESULTS: The overall prevalence of ticks, fleas and lice in dogs was 36.7%, 69.7% and 4.7%, respectively. Similarly, on cats, an overall prevalence of 2.7% ticks and 21.8% fleas was recorded. On dogs, fleas (Ctenocephalides felis 69.4%, Echidnophaga gallinacea 1.3%, Ctenocephalides canis 1.0% and Pulex irritans 0.3%), ticks (Amblyomma variegatum 22.9%, Rhipicephalus sanguineus 14.1%, Haemaphysalis leachi 8.8%, Rhipicephalus praetextatus 4.0% and Rhipicephalus pulchellus 3.4%) and lice (Heterodoxus spiniger 4.0% and Trichodectes canis 0.7%) were identified. Likewise, on cats, fleas (C. felis [15.5%] and E. gallinacea [7.3%]) and ticks (H. leachi [2.7%]) were identified. The abundance of C. felis was significantly higher (p < 0.001) on dogs, whereas in cats, the abundance of E. gallinacea was significantly higher (p = 0.002) than the other ectoparasites. On dogs, a significantly higher prevalence of Rh. sanguineus was recorded in urban areas (<0.001) and on dogs which live in indoor environments (p = 0.003) than on dogs which live in other environments. On the other hand, the prevalence of A. variegatum in rural areas and midland agroecology was significantly higher (p < 0.001). The prevalence of H. leachi was significantly higher in midland (p < 0.001) and on adult dogs (p = 0.001). Overall, fleas were more prevalent in rural (p = 0.029) than in urban areas, and female dogs were with higher infestation than the male (p = 0.047) dogs; C. felis was prevalent in female (p = 0.038) dogs than males. Overall, 88.3% owners in the study area had no knowledge about ectoparasites and VBDs of dogs and cats. Majority of the owners (64.8%) attest that they had never visited veterinary clinics. CONCLUSIONS: In conclusion, the data presented in the present study provide additional knowledge on the importance of ectoparasites of dogs and cats and are believed to contribute in awareness creation and strengthening of veterinary services of dogs and cats of the study area.

The Evolution of Local Co-occurrence in Birds in Relation to Latitude, Degree of Sympatry, and Range Symmetry.

AbstractRecent speciation rates and the degree of range-wide sympatry are usually higher farther from the equator. Is there also a higher degree of secondary syntopy (coexistence in local assemblages in sympatry) at higher latitudes and, subsequently, an increase in local species richness? We studied the evolution of syntopy in passerine birds using worldwide species distribution data. We chose recently diverged species pairs from subclades not older than 5 or 7 million years, range-wide degree of sympatry not lower than 5% or 25%, and three definitions of the breeding season. We related their syntopy to latitude, the degree of sympatry (breeding range overlap), range symmetry, and the age of split. Syntopy was positively related to latitude, but it did not differ between tropical and temperate regions, instead increasing from the Southern to the Northern Hemisphere. Syntopy was also higher in species pairs with a higher degree of sympatry and more symmetric ranges, but it did not predict local species richness. Following speciation, species in the Northern Hemisphere presumably achieve positive local co-occurrence faster than elsewhere, which could facilitate their higher speciation rates. However, this does not seem to be linked to local species richness, which is probably governed by other processes.

Competitive Displacement and Agonistic Character Displacement, or the Ghost of Interference Competition.

AbstractInterference competition can drive species apart in habitat use through competitive displacement in ecological time and agonistic character displacement (ACD) over evolutionary time. As predicted by ACD theory, sympatric species of rubyspot damselflies (Hetaerina spp.) that respond more aggressively to each other in staged encounters differ more in microhabitat use. However, the same pattern could arise from competitive displacement if dominant species actively exclude subordinate species from preferred microhabitats. The degree to which habitat partitioning is caused by competitive displacement can be assessed with removal experiments. We carried out removal experiments with three species pairs of rubyspot damselflies. With competitive displacement, removing dominant species should allow subordinate species to shift into the dominant species' microhabitat. Instead, we found that species-specific microhabitat use persisted after the experimental removals. Thus, the previously documented association between heterospecific aggression and microhabitat partitioning in this genus is most likely a product of divergence in habitat preferences caused by interference competition in the evolutionary past.

Divergent warning patterns influence male and female mating behaviours in a tropical butterfly.

Traits under divergent ecological selection that also function during mating can be important in maintaining species boundaries. Few studies have considered mutual mate choice, where both males and females base mating decisions on the same trait. Wing colouration in Heliconius butterflies evolved as a warning signal but also functions as a mating cue. We investigated the contribution of visual preference to assortative mating in an aposematic butterfly Heliconius cydno in the context of reproductive isolation with its sympatric, visually distinct relative Heliconius melpomene. Heliconius cydno have conspicuous white bands on their forewings, whereas those of H. melpomene are red in colour. We predicted that both sexes of H. cydno contributed to assortative mating by exhibiting visual preference towards conspecific wing colouration. We analysed published and new data from preference experiments, in which males were presented with conspecific and H. melpomene females. We also recorded female responses and mating outcomes in choice experiments, involving conspecific males with either the original white or artificially painted red forewing bands. Both sexes of H. cydno responded more positively towards the conspecific colouration, and males strongly preferred females of its own colours. In contrast, male colouration did not predict mating outcomes in female choice experiments. As courtships are initiated by males in butterflies, our findings suggest that female visual preference might be of secondary importance in H. cydno. Our data also suggest that the contribution of visual preference to reproductive isolation might be unequal between H. cydno and its sympatric relative H. melpomene.

How Important Is Sexual Isolation to Speciation?

A central role for sexual isolation in the formation of new species and establishment of species boundaries has been noticed since Darwin and is frequently emphasized in the modern literature on speciation. However, an objective evaluation of when and how sexual isolation plays a role in speciation has been carried out in few taxa. We discuss three approaches for assessing the importance of sexual isolation relative to other reproductive barriers, including the relative evolutionary rate of sexual trait differentiation, the relative strength of sexual isolation in sympatry, and the role of sexual isolation in the long-term persistence of diverging forms. First, we evaluate evidence as to whether sexual isolation evolves faster than other reproductive barriers during the early stages of divergence. Second, we discuss available evidence as to whether sexual isolation is as strong or stronger than other barriers between closely related sympatric species. Finally, we consider the effect of sexual isolation on long-term species persistence, relative to other reproductive barriers. We highlight challenges to our knowledge of and opportunities to improve upon our understanding of sexual isolation from different phases of the speciation process.

Ecological character displacement among Nothobranchius annual killifishes in Tanzania.

Divergent ecological character displacement (ECD) is the competition-driven divergence in resource use-related phenotypic traits between coexisting species. It is considered one of the primary drivers of ecological diversification and adaptive radiation. We analyzed phenotypic and ecological variation in 2 African annual killifish species of the genus Nothobranchius: N. eggersi and N. melanospilus in sympatry and N. melanospilus in allopatry. Our aim was to test whether allopatric and sympatric populations of N. melanospilus differ morphologically from each other and from N. eggersi and examine whether these differences are consistent with the predictions of ECD. We find that sympatric N. melanospilus differ from allopatric N. melanospilus and differ from N. eggersi more strongly than the latter. Our data satisfy four criteria for demonstrating ECD: Differences in phenotypes between allopatric and sympatric N. melanospilus are greater than expected by chance; the divergence pattern between allopatric and sympatric N. melanospilus results from an evolutionary shift rather than from ecological sorting; morphological differences observed reflect differences in resource use; and, lastly, sites of allopatry and sympatry do not differ in food resource availability or other ecological conditions. Our results suggest that competition is the main driver of the observed divergence between two N. melanospilus populations.

Sympatry and parapatry among rocky reef cichlids of Lake Victoria explained by female mating preferences.

Work on the Lake Victoria cichlids Pundamilia nyererei (red dorsum males, deeper water), Pundamilia pundamilia (blue males, shallower water) and related species pairs has provided insights into processes of speciation. Here, we investigate the female mating behaviour of 5 Pundamilia species and 4 of their F1 hybrids through mate choice trials and paternity testing. Complete assortative mating was observed among all sympatric species. Parapatric species with similar depth habitat distributions interbred whereas other parapatric and allopatric species showed complete assortative mating. F1 hybrids mated exclusively with species accepted by females of the parental species. The existence of complete assortative mating among some currently allopatric species suggests that pre-existing mating barriers could be sufficient to explain current patterns of co-existence, although, of course, many other factors may be involved. Regardless of the mechanism, mating preferences may influence species distribution in potentially hybridizing taxa, such as in the adaptive radiation of cichlid fish. We suggest that this at least partly explains why some species fail to establish breeding populations in locations where they are occasionally recorded. Our results support the notion that the mating preferences of potentially cross-breeding species ought to be included in coexistence theory.

Ecological disruptive selection acting on quantitative loci can drive sympatric speciation.

The process of speciation generates biodiversity. According to the null model of speciation, barriers between populations arise in allopatry, where, prior to biology, geography imposes barriers to gene flow. On the other hand, sympatric speciation requires that the process of speciation happen in the absence of a geographical barrier, where the members of the population have no spatial, temporal barriers. Several attempts have been made to theoretically identify the conditions in which speciation can occur in sympatry. However, these efforts suffer from several limitations. We propose a model for sympatric speciation based on adaptation for resource utilization. We use a genetics-based model to investigate the relative roles of prezygotic and postzygotic barriers, from the context of ecological disruptive selection, sexual selection, and genetic architecture, in causing and maintaining sympatric speciation. Our results show that sexual selection that acts on secondary sexual traits does not play any role in the process of speciation in sympatry and that assortative mating based on an ecologically relevant trait forces the population to show an adaptive response. We also demonstrate that understanding the genetic architecture of the trait under ecological selection is very important and that it is not required for the strength of ecological disruptive selection to be very high in order for speciation to occur in sympatry. Our results provide an insight into the kind of scenarios in which sympatric speciation can be demonstrated in the lab.

Habitat partitioning among sympatric tinamous in semiarid woodlands of central Argentina.

Sympatric, phylogenetically related and morphologically similar species that overlap in their distributions at a regional scale display different patterns of co-occurrence at local assemblages. Occurrence of each species at local scales might be the result of interspecific competition for limiting resources. However, these patterns could also arise from species-specific habitat preferences along the abiotic or land use gradients. To assess the role of these mechanisms, we investigated niche partitioning among sympatric tinamou species occurring in semiarid woodlands of central Argentina. We used occupancy models incorporating habitat characteristics and interspecific interactions, while accounting for detectability, to examine the spatial overlap among elegant crested tinamous (Eudromia elegans), brushland tinamous (Nothoprocta cinerascens), and nothura tinamous (Nothura darwinii and N. maculosa) across a wide regional scale. In addition, we investigated time partitioning among these species by estimating the degree of overlap in their daily activity patterns. The regional distribution of the three species was influenced by the gradient in plant productivity and vegetation structure, in agreement with their broad habitat requirements. We also found that the occurrence of each species was presumably affected by the presence of one or two predator species. Models including interactions among tinamou species found weak negative and positive interactions among species pairs, suggesting that co-occurrence patterns were mainly driven by species-specific habitat use rather than interspecific competition. The three species were diurnal, showing two main peaks of activity, and overlapped widely in their overall diel activity, although subordinate species tended to shift their activity patterns to reduce encounters with the dominant tinamou species, suggesting some segregation in this niche dimension. Projected changes in rainfall seasonality and warmer conditions in this region could benefit elegant crested tinamous over the other two species, although climate and land use changes will likely have a negative impact on all tinamou species.

Climate warming has divergent physiological impacts on sympatric lizards.

Climate warming is expected to affect the vulnerability of sympatric species differentially due to their divergent traits, but the underlying physiological mechanisms of those impacts are poorly understood. We conducted field warming experiments (present climate vs. warm climate) using open-top chambers to determine the effects of climate warming on active body temperature, oxidative damage, immune competence, growth and survival in two sympatric desert-dwelling lizards, Eremias multiocellata and Eremias argus from May 2019 to September 2020. Our climate warming treatment did not affect survival of the two species, but it did increase active body temperatures and growth rate in E. multiocellata compared to E. argus. Climate warming also induced greater oxidative damage (higher malondialdehyde content and catalase activity) in E. multiocellata, but not in E. argus. Further, climate warming increased immune competence in E. multiocellata, but decreased immune competence in E. argus, with regards to white blood cell counts, bacteria killing ability and relative expression of immunoglobulin M. Our results suggest that climate warming enhances body temperature, and thereby oxidative stress, immune competence and growth in E. multiocellata, but decreases immune competence of E. argus, perhaps as a cost of thermoregulation to maintain body temperatures under climate warming. The divergent physiological effects of climate warming on sympatric species may have profound ecological consequences if it eventually leads to changes in reproductive activities, population dynamics and community structure. Our study highlights the importance of considering interspecific differences in physiological traits when we evaluate the impact of climate warming on organisms, even for those closely-related species coexisting within the same geographical area.

Phylogenomics of the narrowly endemic Eurycheilichthys (Siluriformes: Loricariidae): Sympatric species with non-sister relationships suggest mainly allopatric speciation.

Armored catfishes of the genus Eurycheilichthys are endemic to Southern Brazil and Misiones (Argentina) comprising nine species of small size, with a high degree of sympatry and species diversity distributed in two river basins. Here we use new genome-wide data to infer a species phylogeny and test species boundaries for this poorly known group. We estimate 1) the phylogenetic relationships of the species of Eurycheilichthys based on 29,350 loci in 65 individuals of nine species plus outgroups, and 2) the population structure and differentiation based on 43,712 loci and 62 individuals to estimate how geography may have acted on speciation and formation of the sympatric species groups. Analyses support the monophyly of the genus and suggest two species-inclusive clades (East and West) with high support and very recently diverged species. Western clade contains E. limulus (from upper Jacuí River basin) that is sister to Western species of the Taquari-Antas basin plus E. paucidens. The Eastern clade contains E. pantherinus (from Uruguay River basin) sister to the Eastern species of the Taquari-Antas basin E. coryphaenus, plus the central-distributed species E. planus and E. vacariensis, and the more widely-distributed species E. luisae. Eurycheilichthys luisae is not monophyletic and may contain one or more cryptic species or hybrid individuals. A stronger diversity on structure of lineages on the Taquari-Antas, when compared to upper Uruguay and Jacuí River basins, and the fact that most of the sympatrically distributed taxa have non-sister relationships suggest a scenario of mainly allopatric speciation and may indicate a more dynamic landscape with headwater capture events among these tributaries.

Cryptic Diversity in Sympatric Migonemyia migonei (Diptera: Psychodidae), Eventual Meaning for Leishmaniasis Transmission.

Migonemyia migonei (FranÒ«a, 1920) (Diptera: Psychodidae) belongs to the subfamily Phlebotominae, of epidemiological importance due to its role as a vector in leishmaniasis transmission cycles and its broad geographic distribution in South America. Few morphometric and genetic studies have demonstrated the existence of variability among geographically distant populations in Brazil. The aim of the study was to estimate the genetic distance within the morphospecies Mg. migonei through the analysis of cytochrome C oxidase subunit I (COI) sequences of specimens captured in Argentina and those available in online databases. The COI sequences from specimens collected in different localities of Argentina and sequences available in online databases were utilized. Genetic distances were analyzed and a median-joining haplotype network was constructed. Finally, phylogenetic reconstruction was performed according to Bayesian inference. The analyses led to the identification of at least two haplogroups: haplogroup I with sequences of specimens from Colombia, Brazil and Argentina, and haplogroup II with sequences of specimens from Argentina. Interestingly, specimens from Argentina whose haplotypes corresponded to both haplogroups, were collected in sympatry. The results suggest that Mg. migonei could be a species complex with at least two distinct members. This hypothesis could explain the known characteristics of adaptability and vector permissiveness of the species, as the putative cryptic species of the complex could differ in traits of epidemiological importance.

Competitive interactions and coexistence of sympatric flagship carnivores in Asia.

Understanding the competition and coexistence of flagship carnivores is key to creating strategies for their conservation in the face of global carnivore declines. Although studies exploring the dynamics and competition between tigers (Panthera tigris) and leopards (P. pardus) span decades, there is a lack of understanding regarding the factors that influence their coexistence mechanisms on a broad scale, as well as the drivers determining their exploitative and interference competition. We gathered a comprehensive list of research papers among which 36 papers explored the interspecific interactions between tigers and leopards and tested the influence of biotic and abiotic factors on the coexistence mechanisms along three dimensions using multiple response variables regression models; we also tested the influence of ecological drivers determining the exploitative or interference competition between tigers and leopards. Elevation and ungulate density were the most important predictors in regulating the coexistence mechanisms. Tigers and leopards exhibited more positive relations/higher overlaps as elevation increased in the spatial niche. In addition, they showed a higher dietary overlap in the prey-rich regions. We determined that interference competition between tigers and leopards was less frequently observed in habitats with dense tree cover and homogeneous vegetation structures. Meanwhile, studies with multiple metrics would promote the detection of interference competition. Our study provides new insight into the competitive interactions and coexistence mechanisms of tigers and leopards on a broad scale. Policy-makers and managers should pay more attention to the factors of elevation, prey abundance, and habitat structures for the conservation of tigers and leopards.

The effectiveness of using giant panda as a surrogate for protecting sympatric species.

The use of umbrella species to promote biodiversity conservation is practiced worldwide. The giant panda (Ailuropoda melanoleuca) an iconic species for world wildlife conservation, that inhabits regions with significant biodiversity. Given that the functions at wildlife of different trophic levels and in different body size groups are different within the ecosystem, it is unknown whether those groups of wildlife co-occurring with giant pandas are each likewise protected. To examine the umbrella effect of giant pandas on sympatric species, we used an extensive dataset of wildlife from more than 78% of giant panda habitats. We analysed the changes in distribution for four wildlife categories (large carnivores, large herbivores, medium carnivores and medium herbivores) using a generalized linear mixed model, and the underlying driving factors using binomial logistic regression models. Changes in forests in giant panda habitats were evaluated using Fragstats. The results have shown that the counts of herbivores and medium carnivores increased significantly during the decade. However, those of large carnivores significantly declined. Forest cover and nature reserves showed significant and positive effects on wildlife in 2001 and 2011, while the human population had significant and negative impacts on the herbivores and carnivores. Our results have also suggested that there has been a slight alleviation in forest fragmentation in areas unaffected by earthquakes. We concluded that the umbrella strategy of using the giant panda as an umbrella species achieved partial success by promoting the recovery of herbivores and medium carnivores. Meanwhile, this has indicated that the strategy was not sufficient for large carnivores, and therefore not enough for local ecosystems, given the critical role of large carnivores. We have suggested integrating habitat patches, controlling human disturbance, and preparing for potential human-wildlife conflict management in the Giant Panda National Park to restore large carnivore populations and maintain ecosystem functioning.

What triggers phenological events in plants under seasonal environments? A study with phylogenetically related plant species in sympatry / O que desencadeia eventos fenológicos em plantas em ambientes sazonais? Um estudo com espécies de plantas filogeneticamente relacionadas e em simpatria

In this study, we evaluated variation in vegetative and reproductive phenological events of four phylogenetically related plant species subjected to a seasonal environment. To this aim, we sampled 15 individuals of each plant species every fortnight for one year, between January and December of 2017. To assess when a given phenophase occurred more intensely in the population, the Fournier intensity index was used and the synchrony of individuals of the sample in a given phenological event was estimated using the activity index. The Rayleigh (Z) test was used to determine whether the phenological events have seasonal distribution. The relationship of abiotic factors (photoperiod, precipitation, relative humidity and temperature) with the intensity of phenophases was evaluated for each plant species using generalized linear models (GLMs). The phenophases of all plants showed a seasonal distribution pattern, as well as variation in synchrony of phenophases and specific sets of abiotic factors significantly influenced their phenophases. New leaves, for example, were produced throughout the seasons, with intense leaf fall in the dry season. Flowering periods, on the other hand, did not overlap. Indeed, species exhibited sequential flowering and asynchronous flowering among individuals. Our results suggest that the phenological patterns of four sympatric plant species are directly linked to climatic variables, but different abiotic factors affected different phenophases.

Neste estudo, avaliamos a variação nos eventos fenológicos vegetativos e reprodutivos de quatro espécies de plantas filogeneticamente relacionadas submetidas a um ambiente sazonal. Para isso, amostramos 15 indivíduos de cada espécie quinzenalmente, pelo período de um ano, entre janeiro e dezembro de 2017. Para avaliar quando uma determinada fenofase ocorreu de modo mais intenso na população foi utilizado o índice de intensidade de Fournier e a sincronia dos indivíduos da amostra em determinado evento fenológico foi estimada utilizando-se o índice de atividade. O teste de Rayleigh (Z) foi usado para determinar se os eventos fenológicos têm distribuição sazonal. A relação dos fatores abióticos (fotoperíodo, precipitação, temperatura e umidade relativa) com a intensidade das fenofases foi avaliada para cada espécie de planta usando modelos lineares generalizados (GLMs). As fenofases de todas as plantas apresentaram um padrão de distribuição sazonal, bem como variação na sincronia das fenofases e conjuntos específicos de fatores abióticos influenciaram significativamente suas fenofases. Folhas novas, por exemplo, foram produzidas ao longo das estações, com intensa queda de folhas na estação seca. Os períodos de floração, por outro lado, não se sobrepuseram. De fato, as espécies exibiram floração sequencial e floração assíncrona entre os indivíduos. Nossos resultados sugerem que os padrões fenológicos das quatro espécies de plantas simpátricas estão diretamente ligados às variáveis climáticas, mas diferentes fatores abióticos afetaram diferentes fenofases.

An experimental test of the evolutionary consequences of sympatry in Drosophila subquinaria.

Prezygotic isolation is often stronger between sympatric as opposed to allopatric taxa, but the underlying cause can be difficult to infer from comparative studies alone. Experimental evolution, where evolutionary responses to treatments manipulating the presence/absence of heterospecific individuals are tracked, can provide a powerful complementary approach. We used experimental evolution to investigate a naturally occurring pattern of reproductive character displacement in the mushroom-feeding fly, Drosophila subquinaria. In nature, female D. subquinaria from populations sympatric with the closely related Drosophila recens discriminate more strongly against heterospecific males than do females from allopatric populations. Starting with 16 replicate allopatric populations of D. subquinaria, we manipulated the presence/absence of D. recens during mating (experimental sympatry vs. control) and, when present, we allowed hybrids to live or kill them each generation. Across 12 generations, heterospecific offspring production from no-choice mating trials between D. subquinaria females and D. recens males declined in both experimental sympatry treatments relative to the control, suggesting increased sexual isolation. Male cuticular hydrocarbon profiles also evolved, but only in the hybrids killed treatment. Our results strongly imply that the existing reproductive character displacement in wild D. subquinaria populations was an evolutionary response to selection arising from secondary contact with D. recens.

Comparative transcriptomic analysis of chemoreceptors in two sympatric scarab beetles, Hylamorpha elegans and Brachysternus prasinus.

Chemoreception through odorant receptors (ORs), ionotropic receptors (IRs) and gustatory receptors (GRs) represents the functions of key proteins in the chemical ecology of insects. Recent studies have identified chemoreceptors in coleopterans, facilitating the evolutionary analysis of not only ORs but also IRs and GRs. Thus, Cerambycidae, Tenebrionidae and Curculionidae have received increased attention. However, knowledge of the chemoreceptors from Scarabaeidae is still limited, particularly for those that are sympatric. Considering the roles of chemoreceptors, this analysis could shed light on evolutionary processes in the context of sympatry. Therefore, the aim of this study was to identify and compare the repertoires of ORs, GRs and IRs between two sympatric scarab beetles, Hylamorpha elegans and Brachysternus prasinus. Here, construction of the antennal transcriptomes of both scarab beetle species and analyses of their phylogeny, molecular evolution and relative expression were performed. Thus, 119 new candidate chemoreceptors were identified for the first time, including 17 transcripts for B. prasinus (1 GR, 3 IRs and 13 ORs) and 102 for H. elegans (22 GRs, 14 IRs and 66 ORs). Orthologs between the two scarab beetle species were found, revealing specific expansions as well as absence in some clades. Purifying selection appears to have occurred on H. elegans and B. prasinus ORs. Further efforts will be focused on target identification to characterize kairomone and/or pheromone receptors.

Diet in phenotypically divergent sympatric species of African weakly electric fish (genus: Campylomormyrus)-A hybrid capture/HTS metabarcoding approach.

Ecological speciation within the mormyrid genus Campylomormyrus resulted in sympatric species exhibiting divergence in their feeding apparatus and electric organ discharge (EOD). This study documents the overall diet of the genus Campylomormyrus and examines the hypothesis that the Campylomormyrus radiation is caused by adaptation to different food sources. We performed diet assessment of five sympatric Campylomormyrus species (C. alces, C. compressirostris, C. curvirostris, C. tshokwe, C. numenius) and their sister taxon Gnathonemus petersii with markedly different snout morphologies and EODs using hybrid capture/HTS DNA metabarcoding of their stomach contents. Our approach allowed for high taxonomic resolution of prey items, including benthic invertebrates, allochthonous invertebrates and vegetation. Comparisons of the diet compositions using quantitative measures and diet overlap indices revealed that all species are able to exploit multiple food niches in their habitats, that is fauna at the bottom, the water surface and the water column. A major part of the diet is larvae of aquatic insects, such as dipterans, coleopterans and trichopterans, known to occur in holes and interstitial spaces of the substrate. The results indicate that different snout morphologies and the associated divergence in the EOD could translate into different prey spectra. This suggests that the diversification in EOD and/or morphology of the feeding apparatus could be under functional adaptation.