Skipping ahead: A circuit for representing the past, present, and future

Envisioning the future is intuitively linked to our ability to remember the past. Within the memory system, substantial work has demonstrated the involvement of the prefrontal cortex and the hippocampus in representing the past and present. Recent data shows that both the prefrontal cortex and the hippocampus encode future trajectories, which are segregated in time by alternating cycles of the theta rhythm. Here, we discuss how information is temporally organized by these brain regions supported by the medial septum, nucleus reuniens, and parahippocampal regions. Finally, we highlight a brain circuit that we predict is essential for the temporal segregation of future scenarios.

Individual Laterality in Ghost Crabs (Ocypode saratan) Influences Burrowing Behavior

Behavioral handedness is known to enhance an individual’s handling capabilities. However, the ecological advantages in brachyuran crustaceans remain unclear, despite the Ocypode species having been studied extensively. Thus, in this study, we analyzed the laterality of the endemic Red Sea ghost crab on one beach in Eilat, Israel. We successfully documented the laterality of the large cheliped in 125 crabs; in 60 (48.0%), the right cheliped was larger, and in 64 (51.2%), the left. We also observed temporal segregation between the right- and left-clawed crabs. The right-handed crabs start activity just after sunrise, while left-handed crabs appear ca. 40 min after it. Similarly, temporal segregations were also observed in the evening. The right-clawed crab activity peaked ca. 20 min before sunset, while the left-clawed crabs were active uniformly. Additionally, burrow entrances corresponded to the larger cheliped of the resident individual and is probably a self-defense-related behavior. We conclude that cheliped laterality in O. saratan populations should be considered as a bimodal trait, where left- and right-handedness is not under natural selection pressure.

Functional feeding groups of Protist Ciliates (Protist: Ciliophora) on a neotropical flood plain

Functional diversity approaches have been an efficient tool in gaining a better understanding of how environmental conditions selected species in a given environment and how they share resources, linking ecological processes to biodiversity patterns. Although most of the protist ciliates are not highly specialized, functional feeding groups with species which ingest similar food can be identified. Thus, this study aimed to compare the abundance of different Functional Feeding Groups (FFG) of ciliates in environments with different hydrodynamic conditions (lotic and lentic) in different hydrological periods (high and low water) in a neotropical flood plain. The samples for analysis of the community of ciliates were taken in March and September of 2010 and 2011, at the subsurface of 12 different hydrodynamic environments. The results of an RDA showed a spatial and temporal segregation of the sampling units, based on the abundance and occurrence of the FFG. In addition, a clear influence of food resources on the structuring of functional ciliate guilds was evidenced. Thus, there were both temporal (hydrological periods) and spatial (different hydrodynamic environments) differences in the distribution of the FFG, with a clear separation of the FFGs between the years studied. In summary, the results of the categorization of species of ciliates in FFG responded satisfactorily suggesting fluctuations in different food resources, which reinforces the idea that the grouping of species by functional characteristics can be a good indicator of the responses of organisms to environmental fluctuations.

Activity patterns of jaguar and puma and their main prey in the Greater Madidi-Tambopata Landscape (Bolivia, Peru)

Activity pattern studies can help explain the coexistence of competing species. Between 2001 and 2017 we evaluated the activity pattern overlap of jaguar (Panthera onca), puma (Puma concolor), and their main prey, using camera traps at 17 Amazonian sites in the Greater Madidi-Tambopata Landscape. We used the Kernel density estimation to generate species activity patterns and the overlap between both cats. We then calculated the overlap coefficient (Δ) by carrying out 10,000 bootstraps (95%). Both cats were active 24 h a day. The puma has higher nocturnal activity (57%), whilst jaguar activity is split almost equally between night (53%) and day (47%). We did not find temporal segregation between jaguars and pumas, which showed similar activity patterns with a high overlapping coefficient (Δ4 = 0.84; 0.78–0.91). Also, we did not find significant differences between Male and Female activity patterns for both species (X2 = 0.50, gl = 1, P = 0.47). Moreover, both cats had significant overlap with the activity patterns of their main prey. Temporal segregation was not detected in any of our study sites within the Greater Madidi-Tambopata Landscape, suggesting that in this region, these predators employ other mechanisms to avoid competition.

Estimation of spatial and temporal overlap in three ungulate species in a Mediterranean environment

Interspecific interactions are key drivers in structuring animal communities. Sympatric animals may show such behavioural patterns as the differential use of space and/or time to avoid competitive encounters. We took advantage of the ecological conditions of our study area, inhabited by different ungulate species, to investigate the spatial and temporal distribution of Capreolus capreolus, Dama dama and Sus scrofa. We estimated intraspecific interaction arising from the concomitant use of resources by using camera trapping. We collected 2741 videos with the three ungulates, which showed peculiar activity patterns. The three species were observed in all the habitat types of the study area over the four seasons, thus highlighting an evident spatial overlap. Moreover, our analysis demonstrated that the three species did not avoid each other through temporal segregation of their activities, rather showing a high overlap of daily activity rhythms, though with differences among the species and the seasons. Despite the high spatial and temporal overlap, the three species seemed to adopt segregation through fine-scale spatial avoidance: at an hourly level, the proportion of sites where the species were observed together was relatively low. This spatio-temporal segregation revealed complex and alternative behavioural strategies, which likely facilitated intra-guild sympatry among the studied species. Both temporal and spatio-temporal overlap reached the highest values in summer, when environmental conditions were more demanding. Given these results, we may presume that different drivers (e.g. temperature, human disturbance), which are likely stronger than interspecific interactions, affected activity rhythms and fine-scale spatial use of the studied species.

Convergent morphology and divergent phenology: unravelling the coexistence of mimetic Morpho butterfly species

The emergence and persistence of closely-related species in sympatry is puzzling because the potential gene flow and the common local selective pressures may lead to either merging or competitive exclusion. Some species of Morpho butterflies occurring in sympatry display highly similar wing colour patterns. Associated with erratic flight abilities, their bright colouration may limit predator success and discourage future attacks. The evolution of similar colouration in sympatric species is thus likely under local selection by predators (i.e. escape mimicry). Such phenotypic similarity may promote interspecific territoriality and/or reproductive interference, questioning how closely-related co-mimetic species become sexually isolated and coexist in sympatry. We performed a series of field experiments using flying Morpho dummies placed in a natural habitat where wild males commonly patrol. Analysing the interactions of wild Morpho with different dummies, we show that similarity in wing colour pattern leads to interspecific territoriality and courtship among sympatric species. Using genomic data, we then showed that sympatric Morpho species are surprisingly strictly isolated despite their close relatedness and the observed heterospecific interactions. Finally, using a mark-recapture experiment, we discovered a strong temporal segregation in patrolling activity of males from two co-mimetic sister species. Such divergence in phenology may favour sympatry between closely-related species, despite behavioural interferences induced by the local convergence in colour pattern. Altogether, our findings show that temporal segregation may facilitate the co-existence of closely-related species sharing the same ecological niche, suggesting that phenological shifts may represent an overlooked factor of sympatric speciation. Our study therefore highlights how the evolution of multiple traits may favour species diversification in sympatry by partitioning niche in different dimensions.

Temporal and trophic partitioning promote coexistence between mesocarnivores in a Mediterranean landscape

The partition of the ecological niche can enhance the coexistence of predators due to differences in how they exploit three main resources: food, space, and time, the latter being an axis that remains often unexplored. We studied niche segregation in a Mediterranean mesocarnivore community in sites where the top predator, the Iberian lynx, is absent, addressing simultaneously two niche axes: the temporal and the trophic axes. Temporal overlap between prey and predator and potential competitors was analysed by comparing daily activity patterns of predators and prey species through data obtained by using 24 camera-traps deployed in three different sites of the Doñana National Park. We further examined the trophic dimension by compiling and analysing diet information in the study area and exploring trophic preferences between potential competitors. We found an overall temporal segregation between trophic generalist species while those species which showed higher values of temporal overlap differ largely in their trophic preferences. Furthermore, we observed an overall high degree of overlap between the activity patterns of predators and their putative prey (the common genet vs small mammals and the red fox vs European rabbit). Our study suggests that coexistence of the different species that compose the mesocarnivore assemblage in Mediterranean landscapes can be facilitated by the marked temporal segregation of the generalist species due to a divergence in the activity patterns, but also by differences in trophic preferences by specialist species when their activity patterns overlap.

Activity overlap of carnivores, their potential wild prey, and temporal segregation, with livestock in a Biosphere Reserve in the Chihuahuan Desert

Daily activity is an important aspect of animal behavior and depends both on nutritional and reproductive demands. It also can be modified by—among other factors—interspecific competition, the need to minimize the risk of predation, and human disturbance, such as the presence of cattle. We studied the activity patterns and degree of overlap among carnivores, their potential wild prey, and livestock, in a Biosphere Reserve in the Chihuahuan Desert. There was no temporal segregation among the carnivores. Carnivores synchronized their activity with that of their main prey, the black-tailed jackrabbit (Lepus californicus). In contrast, we did observe temporal segregation between the puma (Puma concolor), coyote (Canis latrans), and bobcat (Lynx rufus), with mule deer (Odocoileus hemionus). There was little activity overlap between predators and livestock (Bos taurus, Equus caballus). However, to avoid conflict resulting from livestock predation we suggest increasing and improving surveillance, and that calves and females close to calving be sheltered. More studies on the multi-niche interactions of livestock and their wild predators are needed to understand daily activity overlap in different seasons, and to better understand the mechanisms of coexistence in protected areas in order to make sound management recommendations to cattle growers and park rangers.