Reproductive Interference Between Animal Species

Unraveling the genomic landscape of Campylorhynchus wrens along western Ecuador's precipitation gradient: Insights into hybridization, isolation by distance, and isolation by the environment

Environmental gradients have the potential to influence genetic differentiation among populations ultimately leading to allopatric speciation. However, environmental gradients can also facilitate hybridization between closely related taxa. We investigated a putative hybrid zone in western Ecuador, involving two polytypic wren species (Aves: Troglodytidae), Campylorhynchus zonatus and C. fasciatus. Our study addressed two primary questions: (1) Is there evidence of population structure and genetic admixture between these taxa in western Ecuador? and (2) What are the relative contributions of isolation by distance and isolation by the environment to the observed genetic differentiation along the environmental gradient in this region? We analyzed 4409 single-nucleotide polymorphisms (SNPs) from 112 blood samples sequenced using ddRadSeq and a de novo assembly. The optimum number of genetic clusters ranged from 2 to 4, aligning with geographic origins, known phylogenetics, and physical or ecological constraints. We observed notable transitions in admixture proportions along the environmental gradient in western Ecuador between C. z. brevirostris and the northern and southern genetic clusters of C. f. pallescens. Genetic differentiation between the two C. f. pallescens populations could be attributed to an unreported potential physical barrier in central western Ecuador, where the proximity of the Andes to the coastline restricts lowland habitats, limiting dispersal and gene flow, especially among dry-habitat specialists. The observed admixture in C. f. pallescens suggests that this subspecies may be a hybrid between C. z. brevirostris and C. fasciatus, with varying degrees of admixture in western Ecuador and northwestern Peru. We found evidence of isolation by distance, while isolation by the environment was less pronounced but still significant for annual mean precipitation and precipitation seasonality. This study enhances our understanding of avian population genomics in tropical regions.

Heterospecific interaction in two beetle species: Males with weapons decrease the reproductive success of species with weaponless males

Many species often show male-male combat for mating opportunities and resources within the species. Sexual selection through this radical combat leads to the evolution of males with exaggerated traits used as weapons, such as horns or mandibles, that often result in victory during combat. However, heterospecific interaction due to errors in species identification has often been observed, which results in decreased mating opportunities within the same species and fewer fertilized eggs. Males with exaggerated weapons may show dominance in resource acquisition over males without weapons and may decrease the reproductive success of the latter due to competition between the two. However, few studies have examined heterospecific interaction focusing on males with or without weapons. In this study, we investigated the effects of the male weapon on reproductive traits in heterospecific interaction in two species: the broad-horned flour beetle (Gnatocerus cornutus), in which males have exaggerated weapon traits; and the red flour beetle (Tribolium castaneum), in which males have no weapon traits. Both species are closely related and use the same food resources. G. cornutus males interfered with the resource acquisition and reproductive opportunities of T. castaneum by attacking T. castaneum. The reproductive success of T. castaneum decreased when they cohabited with G. cornutus males. These findings show that male weapon traits, which are important for sexual selection within the same species, can also greatly influence reproduction in other species.

Polyandry may mitigate the negative impact of reproductive interference among bumblebees in Japan

In social hymenopterans, monandry of the queen is an ancestral trait, and polyandry is a derived trait. Polyandry of the queen is the norm in a limited number of lineages, such as honeybees, leaf-cutting ants, Pogonomyrmex ants, and Vespula wasps, which presumably provide fitness advantages for the whole colony. The queen of the introduced bumblebee, Bombus terrestris, is polyandrous in Japan, whereas it is monandrous in native regions. We hypothesize that polyandry can evolve in a process that avoids the negative impacts of reproductive interference caused by interspecific mating and conducted genetic studies of the invasive species B. terrestris and two native subspecies, Bombus hypocrita sapporoensis and Bombus hypocrita hypocrita, in Japan. Our results revealed that although the native queens of B. hypocrita hypocrita allopatric with B. terrestris were strictly monandrous, the native queens of B. hypocrita sapporoensis sympatric with B. terrestris were polyandrous. These results suggested that the queens of native B. hypocrita sapporoensis do not experience negative impacts on interspecific mating from the invasive B. terrestris. We discuss the possibility that reproductive interference is a driving force in selection for multiple mating through an arms race between sympatric species.

Stronger interspecific sexual differences may be favored when females search for mates in the presence of congeners

Why are some species sexually dimorphic while other closely related species are not? While all females in genus Strauzia share a multiply-banded wing pattern typical of many other true fruit flies, males of four species have noticeably elongated wings with banding patterns "coalesced" into a continuous dark streak across much of the wing. We take an integrative phylogenetic approach to explore the evolution of this dimorphism and develop general hypotheses underlying the evolution of wing dimorphism in flies. We find that the origin of coalesced and other darkened male wing patterns correlate with the inferred origin of host plant sharing in Strauzia. While wing shape among non-host-sharing species tended to be conserved across the phylogeny, shapes of male wings for Strauzia species sharing the same host plant were more different from one another than expected under Brownian models of evolution and overall rates of wing shape change differed between non-host-sharing species and host-sharing species. A survey of North American Tephritidae finds just three other genera with specialist species that share host plants. Host-sharing species in these genera also have wing patterns unusual for each genus. Only genus Eutreta is like Strauzia in having the unusual wing patterns only in males, and of genera that have multiple species sharing hosts, only in Eutreta and Strauzia do males hold territories while females search for mates. We hypothesize that in species that share host plants, those where females actively search for males in the presence of congeners may be more likely to evolve sexually dimorphic wing patterns.

Which cues are sexy? The evolution of mate preference in sympatric species reveals the contrasted effect of adaptation and reproductive interference

Mate preferences may target traits (a) enhancing offspring adaptation and (b) reducing heterospecific matings. Because similar selective pressures are acting on traits shared by different sympatric species, preference-enhancing offspring adaptation may increase heterospecific mating, in sharp contrast with the classical case of so-called "magic traits." Using a mathematical model, we study which and how many traits will be used during mate choice, when preferences for locally adapted traits increase heterospecific mating. In particular, we study the evolution of preference toward an adaptive versus a neutral trait in sympatric species. We take into account sensory trade-offs, which may limit the emergence of preference for several traits. Our model highlights that the evolution of preference toward adaptive versus neutral traits depends on the selective regimes acting on traits but also on heterospecific interactions. When the costs of heterospecific interactions are high, mate preference is likely to target neutral traits that become a reliable cue limiting heterospecific matings. We show that the evolution of preference toward a neutral trait benefits from a positive feedback loop: The more preference targets the neutral trait, the more it becomes a reliable cue for species recognition. We then reveal the key role of sensory trade-offs and the cost of choosiness favoring the evolution of preferences targeting adaptive traits, rather than traits reducing heterospecific mating. When sensory trade-offs and the cost of choosiness are low, we also show that preferences targeting multiple traits evolve, improving offspring fitness by both transmitting adapted alleles and reducing heterospecific mating. Altogether, our model aims at reconciling "good gene" and reinforcement models to provide general predictions on the evolution of mate preferences within natural communities.

Vibroscape analysis reveals acoustic niche overlap and plastic alteration of vibratory courtship signals in ground-dwelling wolf spiders

To expand the scope of soundscape ecology to encompass substrate-borne vibrations (i.e. vibroscapes), we analyzed the vibroscape of a deciduous forest floor using contact microphone arrays followed by automated processing of large audio datasets. We then focused on vibratory signaling of ground-dwelling Schizocosa wolf spiders to test for (i) acoustic niche partitioning and (ii) plastic behavioral responses that might reduce the risk of signal interference from substrate-borne noise and conspecific/heterospecific signaling. Two closely related species - S. stridulans and S. uetzi - showed high acoustic niche overlap across space, time, and dominant frequency. Both species show plastic behavioral responses - S. uetzi males shorten their courtship in higher abundance of substrate-borne noise, S. stridulans males increased the duration of their vibratory courtship signals in a higher abundance of conspecific signals, and S. stridulans males decreased vibratory signal complexity in a higher abundance of S. uetzi signals.

Niche differentiation, reproductive interference, and range expansion

Understanding species distributions and predicting future range shifts requires considering all relevant abiotic factors and biotic interactions. Resource competition has received the most attention, but reproductive interference is another widespread biotic interaction that could influence species ranges. Rubyspot damselflies (Hetaerina spp.) exhibit a biogeographic pattern consistent with the hypothesis that reproductive interference has limited range expansion. Here, we use ecological niche models to evaluate whether this pattern could have instead been caused by niche differentiation. We found evidence for climatic niche differentiation, but the species that encounters the least reproductive interference has one of the narrowest and most peripheral niches. These findings strengthen the case that reproductive interference has limited range expansion and also provide a counterexample to the idea that release from negative species interactions triggers niche expansion. We propose that release from reproductive interference enables species to expand in range while specializing on the habitats most suitable for breeding.

Evolution of realized niche breadth diversity driven by community dynamics

Why many herbivorous insects are host plant specialists, with non-negligible exceptions, is a conundrum of evolutionary biology, especially because the host plants are not necessarily optimal larval diets. Here, I present a novel model of host plant preference evolution of two insect species. Because habitat preference evolution is contingent upon demographic dynamics, I integrate the evolutionary framework with the modern coexistence theory. The results show that the two insect species can evolve into a habitat specialist and generalist, when they experience both negative and positive frequency-dependent community dynamics. This happens because the joint action of positive and negative frequency dependence creates multiple (up to nine) eco-evolutionary equilibria. Furthermore, initial condition dependence due to positive frequency dependence allows specialization to poor habitats. Thus, evolved habitat preferences do not necessarily correlate with the performances. The model provides explanations for counterintuitive empirical patterns and mechanistic interpretations for phenomenological models of niche breadth evolution.

Interspecific behavioural interference and range dynamics: current insights and future directions

Novel biotic interactions in shifting communities play a key role in determining the ability of species' ranges to track suitable habitat. To date, the impact of biotic interactions on range dynamics have predominantly been studied in the context of interactions between different trophic levels or, to a lesser extent, exploitative competition between species of the same trophic level. Yet, both theory and a growing number of empirical studies show that interspecific behavioural interference, such as interspecific territorial and mating interactions, can slow down range expansions, preclude coexistence, or drive local extinction, even in the absence of resource competition. We conducted a systematic review of the current empirical research into the consequences of interspecific behavioural interference on range dynamics. Our findings demonstrate there is abundant evidence that behavioural interference by one species can impact the spatial distribution of another. Furthermore, we identify several gaps where more empirical work is needed to test predictions from theory robustly. Finally, we outline several avenues for future research, providing suggestions for how interspecific behavioural interference could be incorporated into existing scientific frameworks for understanding how biotic interactions influence range expansions, such as species distribution models, to build a stronger understanding of the potential consequences of behavioural interference on the outcome of future range dynamics.

Genomic analysis of the rhesus macaque (Macaca mulatta) and the cynomolgus macaque (Macaca fascicularis) uncover polygenic signatures of reinforcement speciation

Speciation can involve phases of divergent adaptation in allopatry and ecological/reproductive character displacement in sympatry or parapatry. Reproductive character displacement can result as a means of preventing hybridization, a process known as reinforcement speciation. In this study, we use whole-genome sequencing (WGS) of two closely related primate species that have experienced introgression in their history, the rhesus (Macaca mulatta) and cynomolgus (M. fascicularis) macaques, to identify genes exhibiting reproductive character displacement and other patterns consistent with reinforcement speciation. Using windowed scans of various population genetic statistics to identify signatures of reinforcement, we find 184 candidate genes associated with a variety of functions, including an overrepresentation of multiple neurological functions and several genes involved in sexual development and gametogenesis. These results are consistent with a variety of genes acting in a reinforcement process between these species. We also find signatures of introgression of the Y-chromosome that confirm previous studies suggesting male-driven introgression of M. mulatta into M. fascicularis populations. This study uses WGS to find evidence of the process of reinforcement in primates that have medical and conservation relevance.

A Case for the "Competitive Exclusion-Tolerance Rule" as a General Cause of Species Turnover along Environmental Gradients

AbstractClosely related, ecologically similar species often segregate their distributions along environmental gradients of time, space, and resources, but previous research suggests diverse underlying causes. Here, we review reciprocal removal studies in nature that experimentally test the role of interactions among species in determining their turnover along environmental gradients. We find consistent evidence for asymmetric exclusion coupled with differences in environmental tolerance causing the segregation of species pairs, where a dominant species excludes a subordinate from benign regions of the gradient but is unable to tolerate challenging regions to which the subordinate species is adapted. Subordinate species were consistently smaller and performed better in regions of the gradient typically occupied by the dominant species compared with their native distribution. These results extend previous ideas contrasting competitive ability with adaptation to abiotic stress to include a broader diversity of species interactions (intraguild predation, reproductive interference) and environmental gradients, including gradients of biotic challenge. Collectively, these findings suggest that adaptation to environmental challenge compromises performance in antagonistic interactions with ecologically similar species. The consistency of this pattern across diverse organisms, environments, and biomes suggests generalizable processes structuring the segregation of ecologically similar species along disparate environmental gradients, a phenomenon that we propose should be named the competitive exclusion-tolerance rule.

Applying Satyrization to Insect Pest Control: The Case of the Spotted Wing Drosophila, Drosophila suzukii Matsumura

Drosophila suzukii represents one of the major agricultural pests worldwide. The identification of safety and long-lasting tools to suppress its populations is therefore crucial to mitigate the environmental and economic damages due to its occurrence. Here, we explore the possibility of using satyrization as a tool to control the abundance of D. suzukii. By using males of D. melanogaster, we realized courtship tests, spermathecae analysis, and multiple-choice experiments to assess the occurrence and extent of pre- and post-zygotic isolation between the two species, as well as the occurrence of fitness costs in D. suzukii females due to satyrization. Our results showed that: (i) D. melanogaster males successfully courted D. suzukii females; (ii) D. melanogaster males significantly affected the total courtship time of D. suzukii males, which reduced from 22.6% to 6.4%; (iii) D. melanogaster males were able to inseminate D. suzukii and reduce their offspring, inducing a high fitness cost. Reproductive interference occurs at different steps between D. melanogaster and D. suzukii, both alone and in combination with other area-wide control approaches.

Female pond frog vocalisation deters sexual coercion by males

Avoiding sexual-conflict-induced sexual coercion is crucial for females, especially in anurans, where the necessity of sexual coercion counterstrategies is increased because of their strong male-male competition and external fertilisation. In this study, we tested the hypothesis that the recently discovered female Pelophylax nigromaculatus calls prevent male courtship and prevented sexual coercion. By observing the reproductive behaviour of anurans, this study examined when females emitted calls and how males responded to them, while comparing the reproductive conditions of call-emitting and non-call-emitting females. The results of this study revealed that females without eggs which were assumed to finish spawning emitted calls in response to male approaches, and the males subsequently moved away from the females obediently. This suggests that female P. nigromaculatus calls work as a counterstrategy against male sexual coercion. This countermeasure communication was first identified in anurans, suggesting that they engage in more complex bidirectional vocal communication during the breeding season than previously assumed.

Female genital concealment and a corresponding male clasping apparatus in Australian ripple bugs (Hemiptera: Veliidae)

Conflicts of interest over reproduction between males and females are widespread in sexually reproducing species. This is exemplified in water striders (Gerridae), where females vigorously resist costly mating attempts, and males and females often exhibit elaborate grasping and anti-grasping morphological traits. Like water striders, their sister-group, the ripple bugs (Veliidae), share similar life histories and are expected to face similar conflicts over mating. Veliids in the genus Nesidovelia exhibit elaborate sexual dimorphism, which is predicted to function in intersexual antagonistic struggles. This includes concealed genitalia in females, and elaborate pregenital abdominal modifications in males. By documenting mating behaviour in Nesidovelia peramoena and freezing pairs in copula, we show that males and females struggle prior to mating, and male abdominal modifications function to gain access to the female's concealed genitalia. This is consistent with, though not limited to, sexual conflict.

Speciation of rock-dwelling snail species: disjunct ranges and mosaic patterns reveal the importance of long-distance dispersal in Chilostoma (Cingulifera) in the European Southern Alps

To better understand the origin of the high diversity and endemism in the Southern Alps of Europe, we investigated the phylogeny and population structure of the rock-dwelling snail group Chilostoma (Cingulifera) in the Southern Alps. We generated genomic ddRAD data and mitochondrial sequences of 104 Cingulifera specimens from 28 populations and 14 other Ariantinae. Until recently, about 30 Cingulifera taxa were classified as subspecies of a single polytypic species. The phylogenetic and population genetic analyses of the ddRAD data and mitochondrial sequences revealed that Cingulifera in the Southern Alps is differentiated into three species. Each of the three Chilostoma (Cingulifera) species occupies disjunct sub-areas, which are separated by areas occupied by other Chilostoma taxa. Neighbouring populations of different species show little or no admixture. Tests indicating that the genetic differentiation of the three Cingulifera taxa cannot be explained by isolation by distance confirmed their species status. The disjunct range patterns demonstrate the importance of stochastic events such as passive long-distance dispersal for the evolution of population structure and speciation in these snails, and of priority effects and ecological competition as important factors influencing species distributions.

Analysis of intrinsic evolutionary factors leading to microendemic distributions in New Caledonian leaf beetles

Microendemicity, or the condition of some species having local ranges, is a relatively common pattern in nature. However, the factors that lead to this pattern are still largely unknown. Most studies addressing this issue tend to focus on extrinsic factors associated with microendemic distributions, such as environmental conditions, hypothesising a posteriori about underlying potential speciation mechanisms, linked or not to these conditions. Here, we use a multi-faceted approach mostly focusing on intrinsic factors instead, namely diversification dynamics and speciation modes in two endemic sibling genera of leaf beetles with microendemic distributions, Taophila and Tricholapita, in a microendemicity hotspot, New Caledonia. Results suggest that the diversification rate in this lineage slowed down through most of the Neogene and consistently with a protracted speciation model possibly combined with several ecological and environmental factors potentially adding rate-slowing effects through time. In turn, species accumulated following successive allopatric speciation cycles, possibly powered by marked geological and climatic changes in the region in the last 25 million years, with daughter species ranges uncorrelated with the time of speciation. In this case, microendemicity seems to reflect a mature state for the system, rather than a temporary condition for recent species, as suggested for many microendemic organisms.

Shifting range in a stingless bee leads to pre-mating reproductive interference between species

Human-induced shifts in species’ ranges can increase contact between closely related species and lead to reproductive interference. In Australia, climate change and trade in stingless bee colonies is increasing the range overlap of two cryptic species: Tetragonula carbonaria and T. hockingsi. To investigate reproductive interactions between these species, we validated a diagnostic-PCR test based on the mitochondrial gene COI to ID field specimens to species. We then assessed the likelihood of reproductive interference in four ways. First, we imaged the male genitalia of each species and found no evidence of reproductive character displacement. Second, we assessed species composition of mating aggregations in an area of sympatry (Southeast Queensland) and confirmed that some males join the mating aggregations of interspecific colonies. Third, we translocated T. hockingsi colonies into the southern range of T. carbonaria (Sydney) and tracked their ability to requeen. These translocated colonies attracted mating aggregations comprised almost entirely of interspecific males, but never formed hybrid colonies; instead, queens either mated with their brothers, or the colony failed to requeen at all. Finally, we presented T. carbonaria males with either conspecific or interspecific virgin queens and found that males attempted to mate only with their own species’ queens. In all, we conclude that reproductive barriers between these species are complete with respect to “short-range” mating cues, but not for “long-range” mate attraction cues. Our study highlights that hive movements can increase some forms of pre-mating reproductive interference between managed bee species, even where the species do not actually mate or hybridize.

Hybridization despite elaborate courtship behavior and female choice in Neotropical tree frogs

The mechanisms of hybridization can be elucidated by analyzing genotypes as well as phenotypes that could act as premating barriers, as the reproductive interactions among heterospecifics can alter the evolutionary history of species. In frogs, hybrids typically occur among species that reproduce explosively (in dense aggregations) with few opportunities for mate selection but are rare in species with elaborate courtship behaviors that may prevent erroneous mating. Using 21 microsatellite markers, we examined hybridization in the prolonged-breeding tree frogs Bokermannohyla ibitiguara and B. sazimai sampled within a contact zone in the Brazilian savanna (72 tadpoles; 74 adults). We also compared acoustic and morphological data. We confirmed both parental species genetically; STRUCTURE results confirmed 14 hybrids, 11 of which were second-generation according to NEWHYBRIDS, all with intermediate values of genetic dissimilarities compared to the parentals. Morphological and acoustic analyses revealed that hybrids showed variable but not necessarily intermediate phenotypes. Moreover, 2 hybrids exhibited call types different from parentals. The reproduction of B. ibitiguara involves territorial and aggressive males, elaborate courtships with acoustic and tactile stimuli, choosy females, and opportunistic strategies. Our study uncovers a rare case of viable hybridization among closely related frogs with such a combination of complex courtship behaviors and mate choice. We discuss the likely directionality and mechanisms behind this phenomenon, and highlight the importance of investigating hybridization even in species that show elaborate reproduction and female choice to advance our understanding of animal diversification.

Males and females contribute differently to the evolution of habitat segregation driven by hybridization

Costly heterospecific mating interactions, such as hybridization, select for prezygotic reproductive isolation. One of the potential traits responding to the selection arising from maladaptive hybridization is habitat preference, whose divergence results in interspecific habitat segregation. Theoretical studies have so far assumed that habitat preference is a sexually shared trait. However, male and female habitat preferences can experience different selection pressures. Here, by combining analytical and simulation approaches, we theoretically examine the evolution of sex-specific habitat preferences. Habitat segregation can have demographic consequences, potentially generating eco-evolutionary dynamics. We thus explicitly consider demography in the simulation model. We also vary the degrees of species discrimination to examine how mate choice influences the evolution of habitat preferences. Results show that both sexes can reduce hybridisation risk by settling in the habitats where abundant conspecific mates reside. However, when females can discriminate species, excess conspecific male aggregation intensifies male-male competition for mating opportunities, posing an obstacle to conspecific aggregation. Meanwhile, conspecific female aggregation attracts conspecific males, by offering the mating opportunity. Therefore, under effective species discrimination, females play a leading role in initiating habitat use divergence. Simulations typically result in either the coexistence with established habitat segregation or the extinction of one of the species. The former result is especially likely when the species differ to some extent in habitat preferences upon secondary contact. Our results disentangle the selection pressures acting on male and female habitat preferences, deepening our understanding of the evolutionary process of habitat segregation due to hybridization.

Comparative reproductive biology of two sympatric Hypostomus in a Neotropical river

Congeneric species often coexist in sympatry using behavioral and morphological adaptations to reduce competition and interspecific interference, but reproductive patterns behind coexistence remain unknown. We analyzed the gonadal morphology and development, reproductive cycle, and population structure of two sympatric congeneric fishes to evaluate the degree of overlap and differentiation of the reproductive biology between species in a Neotropical river. Development of testes and ovaries were similar between species, both showing asynchronous gonadal development, large diameter of gametes and synthesis of mucosubstances by follicle cells to form adhesive eggs. Although the morphometry of germ cells did not present differences, the zona radiata of mature eggs in Hypostomus garmani was markedly thicker than H. francisci, which suggests different spawning habitats. Both species have greater reproductive activity in the rainy season, concomitant with increase in water temperature, however H. garmani initiates and ends its reproduction earlier than H. francisci, indicating a differentiation of reproductive periods. Sexually mature males and females of H. francisci reproduced at a larger mean size then H. garmani. The two congeneric species had a similar abundance and sex ratios in the study area. Results show that although the species exhibited broad overlap of reproductive traits, a spatial and temporal differentiation of the reproductive biology was present. This study contributes to understanding reproductive mechanisms that may facilitate coexistence between congeneric sympatric species.

An evolutionary framework for understanding habitat partitioning in plants

Many plant species with overlapping geographic ranges segregate at smaller spatial scales. This spatial segregation-zonation when it follows an abiotic gradient and habitat partitioning when it does not-has been experimentally investigated for over a century often using distantly related taxa, such as different genera of algae or barnacles. In those foundational studies, trade-offs between stress tolerance and competitive ability were found to be the major driving factors of habitat partitioning for both animals and plants. Yet, the evolutionary relationships among segregating species are usually not taken into account. Since close relatives are hypothesized to compete more intensely and are more likely to interact during mating compared to distant relatives, the mechanisms underlying habitat partitioning may differ depending on the relatedness of the species in question. Here, I propose an integration of ecological and evolutionary factors contributing to habitat partitioning in plants, specifically how the relative contributions of factors predictably change with relatedness of taxa. Interspecific reproductive interactions in particular are understudied, yet important drivers of habitat partitioning. In spatially segregated species, interspecific mating can reduce the fitness of rare immigrants, preventing their establishment and maintaining patterns of spatial segregation. In this synthesis, I review the literature on mechanisms of habitat partitioning in plants within an evolutionary framework, identifying knowledge gaps and detailing future directions for this rapidly growing field of study.

The limits of evolutionary convergence in sympatry: reproductive interference and historical constraints leading to local diversity in warning traits

AbstractMutualistic interactions between defended species represent a striking case of evolutionary convergence in sympatry, driven by the increased protection against predators brought by mimicry in warning traits. However, such convergence is often limited: sympatric defended species frequently display different or imperfectly similar warning traits. The phylogenetic distance between sympatric species may indeed prevent evolution toward the exact same signal. Moreover, warning traits are also involved in mate recognition, so trait convergence might result in heterospecific courtship and mating. Here, we develop a mathematical model to investigate the strength and direction of the evolution of warning traits in defended species with different ancestral traits. Specifically, we determine the effect of phenotypic distances between ancestral trait states of sympatric defended species and of the costs of heterospecific sexual interactions on imperfect mimicry and trait divergence. Our analytical results confirm that reproductive interference and historical constraints limit the convergence of warning traits, leading to either complete divergence or imperfect mimicry. Our model reveals that imperfect mimicry evolves only when ancestral trait values differ between species because of historical constraints and highlights the importance of female and predator discrimination in the evolution of such imperfect mimicry. Our study thus provides new predictions on how reproductive interference interacts with historical constraints and may promote the emergence of novel warning traits, enhancing mimetic diversity.

The First Study of Mating Mistakes in Stoneflies (Plecoptera) from China, with Remarks on Their Biological Implications

Currently, information on the biology of Plecoptera from China is scarce, particularly on mating behavior. In this paper, the existence of mating mistakes (erroneous mating attempts) involving 13 Chinese stonefly species (belonging to nine genera and three families) is reported. These erroneous mating behaviors can be included into three different categories: mating attempts between conspecific males (including the formation of erroneous mating balls), mating attempts between different taxa (including displacement attempts during copulation), and mating-related behaviors with non-living objects. From these behaviors, some aspects of stoneflies during mating, such as the physical competition between males, the sensorial mechanisms implied in triggering a mating behavior, the conditions favoring the mating mistakes, and the possible consequences of interspecific mating in the hybrid production, are discussed.

Pressure for rapid and accurate mate recognition promotes avian-perceived plumage sexual dichromatism in true thrushes (genus: Turdus)

Ecological conditions limiting the time to find a compatible mate or increasing the difficulty in doing so likely promote the evolution of traits used for species and mate recognition. In addition to interspecific character displacement signalling species identity, intraspecific traits that signal an individual's sex and breeding status reduce the challenge of identifying a compatible conspecific mate and should be more common in migratory rather than sedentary species, species with shorter breeding seasons and species breeding under high sympatry with many closely related heterospecifics. Here, we tested this recognition hypothesis for promoting plumage sexual dichromatism in the true thrushes (Turdus spp.), a large and diverse genus of passerine birds. We used receptor-noise limited models of avian vision to quantify avian-perceived chromatic and achromatic visual contrasts between male and female plumage patches and tested the influence of breeding season length, spatial distribution and sympatry with other Turdus species on plumage dichromatism. As predicted, we found that (1) true thrush species with migratory behaviour have greater plumage sexual dichromatism than non-migratory species, (2) species with longer breeding seasons have less plumage sexual dichromatism, and (3) greater numbers of Turdus thrush species breeding in sympatry is associated with more plumage sexual dichromatism. These results suggest that social recognition systems, including species and mate recognition, play a prominent role in the evolution of plumage sexual dichromatism in true thrushes.

Secondary contact rather than coexistence-Erebia butterflies in the Alps

Secondary contact zones are ideal systems to study the processes that govern the evolution of reproductive barriers, especially at advanced stages of the speciation process. An increase in reproductive isolation resulting from selection against maladaptive hybrids is thought to contribute to reproductive barrier buildup in secondary contact zones. Although such processes have been invoked for many systems, it remains unclear to which extent they influence contact zone dynamics in nature. Here, we study a very narrow contact zone between the butterfly species Erebia cassioides and Erebia tyndarus in the Swiss Alps. We quantified phenotypic traits related to wing shape and reproduction as well as ecology to compare the degree of intra- and interspecific differentiation. Even though only very few first-generation hybrids occur, we find no strong indications for current reinforcing selection, suggesting that if reinforcement occurred in our system, it likely operated in the past. Additionally, we show that both species differ less in their ecological niche at the contact zone than elsewhere, which could explain why coexistence between these butterflies may currently not be possible.

Behavioral Comparison in Males of Two Praying Mantis Species of the Same Genus, Hierodula patellifera and H. chinensis (Mantodea: Mantidae: Hierodulinae) in Japan, in Response to the Conspecific or Allospecific Species of Calling Females and Females' Headspace Crude Extract

For many years, only one species of praying mantis in the genus Hierodula, Hierodula patellifera Serville, had been recorded in Japan. In recent years, however, Hierodula chinensis Werner, a larger species than H. patellifera Serville, has been discovered in Japan, and observations and collections in Japan have increased rapidly. There are reports that in some areas, H. patellifera became locally extinct due to the invasion of H. chinensis. Since females of H. patellifera attract conspecific males by volatile with characteristic calling behavior, a sex pheromone-mediated reproductive interference may exist between the two species. Both males of H. patellifera and males of H. chinensis were strongly attracted to conspecific females and crude headspace extract from conspecific females, while they were not attracted to females of allospecific species or crude headspace extract from allospecific females. These results indicate that sex pheromone-mediated reproductive interference may not exist between H. patellifera and H. chinensis.

Evolutionary origins of sexual dimorphism: Lessons from female-limited mimicry in butterflies

The striking female-limited mimicry observed in some butterfly species is a text-book example of sexually dimorphic trait submitted to intense natural selection. Two main evolutionary hypotheses, based on natural and sexual selection respectively, have been proposed. Predation pressure favoring mimicry toward defended species could be higher in females because of their slower flight, and thus overcome developmental constraints favoring the ancestral trait that limits the evolution of mimicry in males but not in females. Alternatively, the evolution of mimicry in males could be limited by female preference for non-mimetic males. However, the evolutionary origin of female preference for non-mimetic males remains unclear. Here, we hypothesize that costly sexual interactions between individuals from distinct sympatric species might intensify because of mimicry, therefore promoting female preference for non-mimetic trait. Using a mathematical model, we compare the evolution of female-limited mimicry when assuming either alternative selective hypotheses. We show that the patterns of divergence of male and female trait from the ancestral traits can differ between these selection regimes. We specifically highlight that divergence in female trait is not a signature of the effect of natural selection. Our results also evidence why female-limited mimicry is more frequently observed in Batesian mimics.

Morphological variation and reproductive isolation in the Hetaerina americana species complex

Incomplete premating barriers in closely related species may result in reproductive interference. This process has different fitness consequences and can lead to three scenarios: niche segregation, sexual exclusion, or reproductive character displacement. In morphologically cryptic species, isolation barriers can be difficult to recognize. Here, we analyzed the morphological, behavioral, and genetic differences between two sympatric cryptic species of the genus Hetaerina to determine the characters that contribute the most to reproductive isolation and the effect of the high rates of behavior interference between the species. We found complete genetic isolation and significant differences in the morphometry of caudal appendages and wing shape, as well as body size variation between species. In contrast, we did not find clear differences in the coloration of the wing spot and observed high rates of interspecific aggression. Our results suggest that divergence in the shape of the caudal appendages is the principal pre-mating barrier that prevents interspecific mating. Moreover, a scenario of character displacement on body size was found. Nevertheless, size could play an important role in both inter- and intrasexual interactions and, therefore, we cannot differentiate if it has resulted from reproductive or aggressive interference.

Coexisting good neighbours: acoustic and calling microhabitat niche partitioning in two elusive syntopic species of balloon frogs, Uperodon systoma and U. globulosus (Anura: Microhylidae) and potential of individual vocal signatures

Background

Most amphibians use a repertoire of acoustic signals to propagate signals in social contexts. The description of these repertoires provides a key towards the understanding of the behaviour of individuals and the evolutionary functions of calls. Here, we assessed the variations in advertisement calls within and between two fossorial sympatric species, Uperodon systoma and Uperodon globulosus, that share their breeding season and breeding sites. For each species, we applied Beecher’s index of total information capacity (HS) for the individual vocal signature, determined the difference in call properties and demonstrated the segregation in the calling microhabitat niche between the two species.

Results

Our results demonstrated that the advertisement calls of U. systoma are pulsatile with a call rate of 3.00 ± 0.97 calls per second while those of U. globulosus are not pulsatile with a lower call rate of 0.53 ± 0.22 calls per second. For both species, the variations in call properties among individuals was higher than that within individual, a pattern consistent with that of other fossorial anurans. The body condition and air temperature did not significantly impact the call properties of either species. The outcome of the Beecher’s index (HS) showed that the calls of U. systoma can be used to identify 14 different individuals and the calls of U. globulosus can be used to identify 26 different individuals. The statistical analyses on the advertisement call of the two species showed a significant difference in the temporal properties as the call duration, and fall time and rise time were significantly different between the two species. Lastly, we successfully demonstrated that there is a clear segregation in calling site microhabitat between the two species, where U. globulosus calls floating close to the bank of the waterbody while U. systoma calls floating further away from the bank.

Conclusion

This study highlights the potential for pre-mating isolation, character displacement and assortative mating in two syntopic fossorial anurans, leading to association between acoustic, calling microhabitat niche and body index divergence as important behavioural and ecological traits.

Interspecific mating bias may drive Aedes albopictus displacement of Aedes aegypti during its range expansion

Aedes albopictus is the most invasive mosquito in the world and often displaces Ae. aegypti in regions where their populations overlap. Interspecific mating has been proposed as a possible cause for this displacement, but whether this applies across the range of their sympatry remains unclear. Aedes albopictus and Ae. aegypti collected from allopatric and sympatric areas in China were allowed to interact in cage experiments with different crosses and sex-choices. The results confirm that asymmetric interspecific mating occurs in these populations with matings between allopatric Ae. albopictus males and Ae. aegypti females being significantly higher (55.2%) than those between Ae. aegypti males and Ae. albopictus females (27.0%), and sympatric mosquitoes showed a similar but lower frequency bias, 25.7% versus 6.2%, respectively. The cross-mated females can mate second time (remate) with the respective conspecific males and the 66.7% remating success of female Ae. albopictus was significantly higher than the 9.3% of Ae. aegypti females. Furthermore, 17.8% of the matings of Ae. albopictus males exposed to mixed pools of Ae. albopictus and Ae. aegypti females and 9.3% of the matings of Ae. aegypti males with mixed Ae. aegypti and Ae. albopictus females were interspecific. The difference in the length of clasper between male Ae. albopictus (0.524 mm) and Ae. aegypti (0.409 mm) may be correlated with corresponding mates. We conclude that stronger Ae. albopictus male interspecific mating and more avid female intraspecific remating result in a satyr effect and contribute to competitive displacement of Ae. aegypti as allopatric Ae. albopictus invade during range expansion.

Using citizen science to test for acoustic niche partitioning in frogs

The acoustic niche hypothesis proposes that to avoid interference with breeding signals, vocal species should evolve to partition acoustic space, minimising similarity with co-occurring signals. Tests of the acoustic niche hypothesis are typically conducted using a single assemblage, with mixed outcomes, but if the process is evolutionarily important, a pattern of reduced acoustic competition should emerge, on average, over many communities. Using a continental-scale dataset derived from audio recordings collected by citizen scientists, we show that frogs do partition acoustic space. Differences in calls were predominately caused by differences in spectral, rather than temporal, features. Specifically, the 90% frequency bandwidths of observed frog assemblages overlapped less than expected, and there was greater distance between dominant frequencies than expected. To our knowledge, this study is the first to use null models to test for acoustic niche partitioning over a large geographic scale.

Reproductive interference and Satyrisation: mechanisms, outcomes and potential use for insect control

Reproductive Interference occurs when interactions between individuals from different species disrupt reproductive processes, resulting in a fitness cost to one or both parties involved. It is typically observed between individuals of closely related species, often upon secondary contact. In both vertebrates and invertebrates, Reproductive Interference is frequently referred to as 'Satyrisation'. It can manifest in various ways, ranging from blocking or reducing the efficacy of mating signals, through to negative effects of heterospecific copulations and the production of sterile or infertile hybrid offspring. The negative fitness effects of Satyrisation in reciprocal matings between species are often asymmetric and it is this aspect, which is most relevant to, and can offer utility in, pest management. In this review, we focus on Satyrisation and outline the mechanisms through which it can operate. We illustrate this by using test cases, and we consider the underlying reasons why the reproductive interactions that comprise Satyrisation occur. We synthesise the key factors affecting the expression of Satyrisation and explore how they have potential utility in developing new routes for the management and control of harmful insects. We consider how Satyrisation might interact with other control mechanisms, and conclude by outlining a framework for its use in control, highlighting some of the important next steps.

Could Sterile Aedes albopictus Male Releases Interfere with Aedes aegypti Population in Reunion Island?

Simple Summary

The Sterile Insect Technique consisting of inundative and repeated releases of sterile males that induce sterility in the wild population is currently tested as a new strategy to control Ae. albopictus. Considering that Ae. albopictus and Ae. aegypti thrive in sympatry in some regions, and that mating between both species is known to occur at low rates, we hypothesize that releasing millions of sterile male Ae. albopictus in could affect female Ae. aegypti reproduction. To study this potential mating interference, the newly established marking technique has been applied using the rhodamine B that is administered to males through sugar meal. It is internally incorporated into the mosquito’s male body and during mating, the rhodamine is transferred into the females. In laboratory-based experiments rhodamine marking proved to be a powerful means of detecting mating in females of both Aedes species, whatever the mating crosses between males and females. Some mated females were able to lay eggs, but all were not viable. However, despite the promiscuity of the adults in small experimental cages, 95% of the female Ae aegypti showed no evidence of insemination following mating with sterile male Ae. albopictus, suggesting that in the field, an inundative and repeated releases of sterile male Ae. albopictus will not influence the reproduction of female Ae aegypti.

Abstract

In Reunion Island, the feasibility of an Aedes albopictus control program using the Sterile Insect Technique (SIT) is studied. Because, in some regions, Ae. albopictus is living in sympatry with Aedes aegypti, the impact of releasing millions of sterile male Ae. albopictus on female Ae. aegypti reproduction needs to be assessed. Thus, to study the potential heterospecific matings, a marking technique using rhodamine B has been used. Rhodamine is given in solution to male mosquitoes to be incorporated into the male body and seminal fluid and transferred during mating into the bursa inseminalis and spermathecae of females. The presence of rhodamine in females occurred in 15% of cases when Ae. aegypti females were offered non-irradiated Ae. albopictus males, 5% when offered irradiated Ae. albopictus males and 18% of cases in the inverse heterospecific matings. Moreover, our results also showed that these matings gave few eggs but were not viable. Finally, the results showed that whatever the type of mating crosses, females in cages previously crossed with males of another species can re-mate with males of their species and produce an equivalent amount of egg compared to females only mated with conspecific males. Despite the promiscuity of the males and females in small cages for three days, heterospecific mating between sterile male Ae. albopictus and female Ae aegypti, 95% of the females have not been inseminated suggesting that in the field the frequency satyrization would be very low.

Comparisons among populations and individuals to evaluate pollen-pistil interaction as a mechanism of reproductive interference in Taraxacum

Reproductive interference (RI), an interspecific mating interaction that reduces the fitness of at least one of the species involved, can lead to exclusive distributions in closely related species. A hypothesis previously proposed is that RI in plants may occur by ovule usurpation, in which pistils lack interspecific incompatibility and mistakenly accept heterospecific pollen, thereby losing an opportunity for conspecific pollen fertilization. However, few comparative studies have evaluated the consistency of the inferred mechanism within and among individuals and populations. We conducted hand-pollination experiments in six populations of three native Taraxacum species that suffered from different levels of RI from an alien congener, T. officinale, and compared pollen-pistil interactions among populations. We also investigated the interactions for eight individual T. japonicum plants whose response to heterospecific pollen deposition had been previously measured. Our results revealed that pollen tubes often penetrated native ovaries following heterospecific pollination in populations suffering from strong RI, whereas they seldom did in populations suffering from marginal RI. However, the relative frequency of the pollen tube penetration was not significantly related to the strength of alien RI. Not all pistils on an individual plant showed the same pollen receptivity following heterospecific pollination; rather, some accepted and some refused the pollen tubes. The relationship between pollen tube penetration following heterospecific pollination and the strength of the alien RI was also not significant among individuals. Our present results generally support the ovule usurpation hypothesis, but suggest that other factors, such as competition for pollinator services, variation in the effects of heterospecific pollen donors, and condition of the native inflorescences, might also affect the observed RI strength.

Convergent morphology and divergent phenology promote the coexistence of Morpho butterfly species

The coexistence of closely-related species in sympatry is puzzling because ecological niche proximity imposes strong competition and reproductive interference. A striking example is the widespread wing pattern convergence of several blue-banded Morpho butterfly species with overlapping ranges of distribution. Here we perform a series of field experiments using flying Morpho dummies placed in a natural habitat. We show that similarity in wing colour pattern indeed leads to interspecific territoriality and courtship among sympatric species. In spite of such behavioural interference, demographic inference from genomic data shows that sympatric closely-related Morpho species are genetically isolated. Mark-recapture experiments in the two most closely-related species unravel a strong temporal segregation in patrolling activity of males. Such divergence in phenology reduces the costs of reproductive interference while simultaneously preserving the benefits of convergence in non-reproductive traits in response to common ecological pressures. Henceforth, the evolution of multiple traits may favour species diversification in sympatry by partitioning niche in different dimensions.

Male courtship reduces the risk of female aggression in web-building spiders but varies in structure

Male courtship serves multiple functions in addition to inducing females to accept them as a mate. In predatory species, male courtship can function to reduce the risk of sexual cannibalism. This is particularly important in web-building spiders in which males risk being mistaken for prey when they enter the female’s predatory trap—the web—in order to commence courtship. Male spiders generate vibrations by shuddering in the female’s web. Shudder vibrations can delay female aggression, even toward prey struggling in the web. We predicted that shudder vibrations are highly conserved across species of web-building spider as males all face the same constraint of not being mistaken for prey by females. We examined how conserved shudder vibrations are across web-building spiders by testing whether female Trichonephila plumipes delay aggressive behavior toward real prey struggling in the web during playback of conspecific or heterospecific (Argiope keyserlingi) male shudder vibrations. We found that while conspecific shudder vibrations do indeed delay female predatory behavior, heterospecific male shudder vibrations do not. There is evidence of shudder or shudder-like vibrations in male courtship behavior across web-building spider families, but these vary in structure. This suggests that despite strong constraints on courtship signal design to separate predatory responses from sexual responses, there is additional selection driving the divergence of signals across distantly related spider species.

Sterile males and females can synergistically suppress wild pests targeted by sterile insect technique

The sterile insect technique (SIT) involves periodically releasing artificially sterilized insects to inhibit normal mating between wild insect pests, ultimately resulting in the eradication of wild pest populations. It has often been discussed whether releasing either one sex, mainly males, of sterile insects (i.e., a unisexual release) can enhance the pest-control effect of the SIT more than releasing both sexes (i.e., a bisexual release). We constructed a mathematical model to examine the contribution of sterile males and females to the pest-control effect and the synergy between them. We consider that males seek out and court females in accord with their own female searching ability and preference, and that females subsequently choose one male from among males courting them in accordance with their own preference. Using this model, we compared the pest-control effect of bisexual and unisexual release, focusing on the difference in mating systems of the targeted insects. We showed that for swarm-type mating systems (with few courtship chances with higher encounter rates), bisexual release was the most effective, irrespective of the relative female searching ability between wild and sterile males. In this case, sterile females indirectly reduce wild females mating with either male by absorbing courtship from both wild and sterile males. By contrast, bisexual release is the most effective for scramble-type mating systems (more courtship chances with lower encounter rates) only when the female searching ability of sterile males is lower than that of wild males. In this case, sterile females absorb courtship from males with higher searching abilities. Therefore, the net impact of sterile females depends on the difference in sexual performance between wild and sterile males. Because the sexual performance of sterile insects is often degraded during the process of sterilization, we suggest that bisexual release can be a compatible measure to efficiently suppress wild pest populations.

Neural basis of acoustic species recognition in a cryptic species complex

Sexual traits that promote species recognition are important drivers of reproductive isolation, especially among closely related species. Identifying neural processes that shape species differences in recognition is crucial for understanding the causal mechanisms of reproductive isolation. Temporal patterns are salient features of sexual signals that are widely used in species recognition by several taxa, including anurans. Recent advances in our understanding of temporal processing by the anuran auditory system provide an opportunity to investigate the neural basis of species-specific recognition. The anuran inferior colliculus consists of neurons that are selective for temporal features of calls. Of potential relevance are auditory neurons known as interval-counting neurons (ICNs) that are often selective for the pulse rate of conspecific advertisement calls. Here, we tested the hypothesis that ICNs mediate acoustic species recognition by exploiting the known differences in temporal selectivity in two cryptic species of gray treefrog (Hyla chrysoscelis and Hyla versicolor). We examined the extent to which the threshold number of pulses required to elicit behavioral responses from females and neural responses from ICNs was similar within each species but potentially different between the two species. In support of our hypothesis, we found that a species difference in behavioral pulse number thresholds closely matched the species difference in neural pulse number thresholds. However, this relationship held only for ICNs that exhibited band-pass tuning for conspecific pulse rates. Together, these findings suggest that differences in temporal processing of a subset of ICNs provide a mechanistic explanation for reproductive isolation between two cryptic treefrog species.

Microbiome diversity and reproductive incompatibility induced by the prevalent endosymbiont Arsenophonus in two species of African cassava Bemisia tabaci whiteflies

A minimum of 13 diverse whitefly species belonging to the Bemisia tabaci (B. tabaci) species complex are known to infest cassava crops in sub-Saharan Africa (SSA), designated as SSA1-13. Of these, the SSA1 and SSA2 are the predominant species colonizing cassava crops in East Africa. The SSA species of B. tabaci harbor diverse bacterial endosymbionts, many of which are known to manipulate insect reproduction. One such symbiont, Arsenophonus, is known to drive its spread by inducing reproductive incompatibility in its insect host and are abundant in SSA species of B. tabaci. However, whether Arsenophonus affects the reproduction of SSA species is unknown. In this study, we investigated both the reproductive compatibility between Arsenophonus infected and uninfected whiteflies by inter-/intraspecific crossing experiments involving the sub-group three haplotypes of the SSA1 (SSA1-SG3), SSA2 species, and their microbial diversity. The number of eggs, nymphs, progenies produced, hatching rate, and survival rate were recorded for each cross. In intra-specific crossing trials, both male and female progenies were produced and thus demonstrated no reproductive incompatibility. However, the total number of eggs laid, nymphs hatched, and the emerged females were low in the intra-species crosses of SSA1-SG3A+, indicating the negative effect of Arsenophonus on whitefly fitness. In contrast, the inter-species crosses between the SSA1-SG3 and SSA2 produced no female progeny and thus demonstrated reproductive incompatibility. The relative frequency of other bacteria colonizing the whiteflies was also investigated using Illumina sequencing of 16S rDNA and diversity indices were recorded. Overall, SSA1-SG3 and SSA2 harbored high microbial diversity with more than 137 bacteria discovered. These results described for the first time the microbiome diversity and the reproductive behaviors of intra-/inter-species of Arsenophonus in whitefly reproduction, which is crucial for understanding the invasion abilities of cassava whiteflies.

A tangled web: Comparing inter- and intraspecific mating dynamics in Anasa squash bugs

Reproductive interference, reproductive interactions between heterospecific individuals including mating, is commonly reported across taxa, but its drivers are still unclear. Studying interspecific matings in the context of their conspecific mating system-by relating an individual's conspecific mating behaviour to its heterospecific interactions-offers a powerful approach to address this uncertainty. Here, we compare inter- and intraspecific mating dynamics in the squash bug Anasa tristis and its close relative Anasa andresii under semi-natural conditions. Using replicated enclosures, we surveyed the mating behaviour of individually marked A. tristis and A. andresii (five males and five females of each species per trial) at hourly intervals using a robotic camera system over a 14-day period. We uncovered high levels of reproductive interference (19% of individuals engaged in interspecific matings), but the majority of mating activity took place between conspecifics. A. tristis females which engaged in interspecific matings had comparable hatching success with those which did not. Therefore, in this system, relatively high levels of reproductive interference may emerge under semi-natural conditions as a by-product of limited intraspecific pre-copulatory choice paired with limited fitness penalties for at least one of the species involved.

Temporal Variation Dominates in Local Carabid Beetle Communities in Korean Mountains

Simple Summary

This study focused on spatial and temporal variation in carabid beetle communities and environmental factors, and the association between them at spatial and temporal scales, based on data collected over 5 years from nine study sites on three mountains. We found that carabid beetle communities exhibited significant temporal variation, and that the patterns of temporal variation differ between mountains. Temporal variation in communities was suggested to occur in response to variations in the local climate. Our results suggest that temporal surveys of communities and climates at local scales are important for predicting temporal changes in communities. Such investigations are expected to reveal an additional fraction of variation in communities, and to provide information on previously overlooked underlying processes, especially with respect to global community patterns and changes in wider spatial scales.

Abstract

Spatial and temporal variation in ecological environments may result in spatial and temporal variation in communities. Temporal studies of biodiversity are essential for forecasting future changes in community structure and ecosystem function. Therefore, determining the mechanisms that drive temporal change in communities remains an important and interesting challenge in ecology. We quantified spatial and temporal variations in carabid beetle communities and site-specific environmental factors for 5 years at nine study sites on three mountains in the Baekdudaegan Mountain Range, Korea. Carabid beetle communities exhibited significant temporal variation, which was larger than spatial variations between and within mountains. Environmental factors mostly varied between sites within mountains. Community variation was only weakly associated with environmental factors at wide scales, i.e., between sites on three mountains, but was strongly associated at narrow spatial scales, i.e., between sites within one mountain. Our results indicate that temporal variation in communities occurs in response to variations in the local climate, and that the patterns of temporal variation differ between mountains. Thus, temporal surveys of insect communities and climates at local scales are important for predicting temporal changes in the communities.