Evolutionary Ecology最新文献

Territoriality is a form of social dominance concerning the use of space that ensures the territory owner primary access to critical resources. The territory is defended with visual displays, advertisement calls, physical attacks, or chemical signals. The territory is frequently estimated by mapping locations where an animal is observed engaging in territorial behavior or by tracking. However, these approaches may over- or underestimate the areas defended. Thus, the use of approaches explicitly determining defended areas is critical to properly characterize the territory. Intrusion experiments can elicit a response in territory holders, allowing one to characterize their aggressive responses; however, the aggressive response depends on the species. We describe an approach to experimentally estimate the territory size using playback experiments in a species that exhibits a stereotypical phonotactic response: the nurse frog, Allobates aff. trilineatus and develop a new behavioral index that allows assessing territory size in response to playbacks for a species with non-stereotyped phonotactic response: the endangered Lehmann’s poison frog, Oophaga lehmanni. We conducted 772 playback experiments on 18 males of A. aff. trilineatus, and 222 on nine males of O. lehmanni. We analyzed the results of playback experiments with three different area estimators regularly used to estimate space use and evaluated whether these estimates are correlated. The shape and size of territories varied among individuals and estimators in both species. Although we found that the absolute size of the territory depends on the method used, estimates were strongly correlated, meaning that different estimators similarly describe variation in territory size among males. Choosing an analysis method may not be particularly important for studying the characteristics of territoriality over space and time but using a systematic and standardized experimental approach that also incorporates the particularities of the aggressive response of each species is essential to understand the evolution of space use by poison frogs and other territorial species.

Floral traits such as color, scent, and nectar often vary substantially within plant species. However, when it comes to pollen chemistry, the scale of intraspecific variation is largely unknown, as are its potential abiotic drivers. Bees collect pollen as their primary source of protein and lipids, and interspecific variation in pollen quality influences bee foraging preferences. Understanding the scale of intraspecific spatiotemporal variation in pollen macronutrient content could further uncover the nutritional basis of many plant-pollinator interactions influenced by geographic and climatic factors. Here, we sampled pollen from 35 bee-visited wildflower species across multiple sites in Great Basin/Eastern Sierra sagebrush steppe habitat (Nevada/California, USA) and analyzed their protein and lipid concentrations. Then, using Bayesian sparse regression, we explored the relationship between 44 site-specific climate variables and variation in pollen nutritional content. In some plant species, we discovered variation in protein or lipid concentrations across sites at a scale likely meaningful to bee performance. Further, this variation was weakly but significantly related to both current season below-ground (climatic water deficit) and previous season above-ground (dewpoint) conditions, uncovering the potential for community interactions mediated by floral nutrition to be altered via multiple plant ecophysiological pathways. Identifying the causes and consequences of variation in pollen nutrition is an effort critical to understanding how climate change impacts plant fitness via interactions with pollinators as well as the health of managed and wild bees.

The Southwest Atlantic (SWA) is an important region for the Caretta caretta characterized by unique genetic lineages; however, their demographic evolution is still misunderstood. In this study, we evaluated the demographic patterns of four SWA rookeries using D-loop and microsatellites data looking for expansion and bottlenecks signals. Then, we simulated several colonization scenarios for the SWA using Approximate Bayesian Computation. The best-supported scenario indicated that loggerheads might have colonized the SWA region once by the ancient lineage of ES/k3 that signals a sharing ancestry history, and from it originated the other lineages by divergence and introgression processes, explaining the high admixture levels between their rookeries and genetic clusters. The D-loop recovered population stability in the past. Still, microsatellites identified sharp recent bottleneck events, which the Last Glacial Maximum, El Niño Southern Oscillation, and anthropogenic actions may have triggered. Thus, we provide, for the first time, a complete assessment of the life history and colonization of loggerhead into the SWA, demonstrating differences between markers (matrilinear and biparental) that may bias our understanding of their genetic and demographic patterns, and which should be considered for conservation programs at a global scale.

Wolbachia, a prevalent endosymbiont amongst arthropods, can effectively invade the host population by inducing cytoplasmic incompatibility (CI). CI occurs when a female parent lacks the Wolbachia strain that is possessed by its male mate, resulting in embryonic death. In the bean beetle, Callosobruchus analis, two distinct Wolbachia strains have been identified: the non-CI-inducing wCana1 and the CI-inducing wCana2. Field-collected C. analis individuals were either singly infected with wCana1 or doubly infected with wCana1 and wCana2. The higher prevalence of wCana1 over wCana2 in C. analis raises the question of why CI-inducing wCana2 is not more widespread. To address this, we measured the egg hatch rates in all the cross combinations between seven C. analis lines differing in Wolbachia infection status. We found that the intensity of CI was highly variable between combinations, which can be attributed to either the host genetic background or intra-strain genetic variation of wCana2. These findings may suggest that CI is susceptible to change and emphasize the need to consider the adaptive nature of host manipulation. Understanding the genetic and environmental factors underlying the CI variation is crucial for predicting the long-term stability of Wolbachia-host associations.

Body size influences ecological interactions between species as well as social interactions within species, eventually affecting the evolution of large-scale biodiversity patterns. Thus, macroecological investigations of body size can connect spatial variation in selection regimes and the evolution of organisms distributed through space. To better understand intra-specific body size variation in ectotherms, we considered eight hypotheses proposed in the literature, asking which best explain the geographical body size variation of Bufo minshanicus, an animal endemic to the eastern Tibetan Plateau, that is broadly distributed across high elevations (1700–3700 m). The body size of B. minshanicus from 4658 adult toads was obtained from 16 study sites, covering the majority of the distributional range of the species. We found that B. minshanicus had larger bodies and higher post-hibernation body condition in areas with greater seasonality (supporting the hibernation hypothesis). In addition, we found that individuals living in populations with lower precipitation and lower annual actual evapotranspiration, as well as high precipitation seasonality are larger (supporting the water availability hypothesis). Larger individuals tend to have an advantage when living in stressful environments due to energy consumption and desiccation rates. We conclude that multiple factors related to seasonality and humidity influence adult body size variation in B. minshanicus.

Why offspring size and number vary in diverse ways with adult body size is little understood. In my comparative analysis of animal taxa, I show that age-specific mortality predicts the interspecific body-mass (BM) scaling of offspring (egg, embryo, or neonate) mass (OM) and number per clutch (CS) with striking accuracy. Across six animal taxa, the mean ratio of juvenile to adult mortality (m_j/m_a) explains 80% and 88% of the variation in BM scaling slopes for OM and CS, respectively. Animal taxa with high parental care and low mj/ma ratios tend to exhibit steeper OM scaling and shallower CS scaling than taxa with low parental care and high m_j/m_a ratios. Even the curvature of OM scaling in logarithmic space can be predicted approximately by the difference in the BM scaling slopes of juvenile and adult mortality rates. The overall triangular pattern of variation in OM in relation to BM in animals can be understood in terms of body-size dependent variation in m_j/m_a, as well. These results are explained by an ‘age-specific mortality hypothesis’, which posits that OM and CS scaling slopes are functions of the relative emphasis of natural selection on offspring versus parental fitness. Therefore, I recommend that future studies of the body-size scaling of life-history traits should include estimates of age-specific mortality. In general, it is becoming clear that a mortality perspective can provide useful insight into many kinds of biological and ecological scaling relationships.

Female sperm storage (FSS) has been reported in Chondrichthyans species, and involves the prolonged maintenance of viable sperm after mating events, prior to egg fertilization. Along with multiple paternity (MP–female producing offspring of multiple males within the same litter), FSS has been hypothesized to be related to the increased reproductive fitness of cartilaginous fish lineages. The present study aimed to investigate if: (1) are FSS and MP evolutionarily related and share the same evolutionary history in Chondrichthyes? (2) How is the presence of FSS implied by extinction and speciation rates and thus related to the current species diversity of the group? To answer these questions, we obtained FSS and MP records for Chondrichthyes species from the literature and performed ancestral reconstruction analyses for each character in the phylogenetic tree. We employed MEDUSA and MiSSE to determine if the shifts in diversification rates were related to the characters along the phylogeny. Finally, we utilized HiSSE to calculate the net diversity rates for observed and unobserved states. The ancestral reconstruction indicates that both characters are plesiomorphic for the group; FSS is suggested to be absent in Lamniformes and Rhinopristiformes, whereas MP may be absent in Galeocerdo cuvier. MEDUSA and MiSSE revealed that all clades lacking FSS showed no increase in rates, while there was a higher diversification rates in clades with FSS. HiSSE identified lower net diversity rates in clades lacking FSS associated with hidden states. Therefore, FSS absence seems to contribute to increased extinction rates by reducing diversity among the Chondrichthyes.

Reproductive patterns observed in organisms are direct outcomes of the interaction among parameters such as phylogeny, body size, and environmental characteristics. However, the action of these parameters is rarely observed in an integrated perspective in the literature. Here, we collected 109 specimens of two congeneric species of treefrogs living in the same microhabitat (bromeligenous species of genus Ololygon) to compare the reproductive patterns of the two species, evaluating the effect of different parameters on the reproductive ecology of the organisms. Our results show that morphometric measurements between females of the two species were not significantly different, indicating similar body sizes. The species exhibited different degrees of sexual dimorphism, and interspecifically, females showed significant differences in breeding traits, with the species O. perpusilla demonstrating higher reproductive effort, characterized by increased ovarian mass and increased average egg size compared to O. littorea. We observed that differences in reproductive effort were strongly associated with egg size, which drove higher reproductive investment in O. perpusilla females. We conclude that although the species share many traits commonly related to the degree of reproductive investment, other drivers, not yet completely understood, may influence the reproductive aspects of organisms, generating unexpected patterns.

The detection of male dimorphism has seen numerous statistical advances. Packard has recently criticized a widely used method, reanalyzing data from beetles and harvestmen using an alternative method. We disagree with Packard conclusions, probably due to different implicit definitions of male dimorphism. We consider that male dimorphism manifests in a distribution when it is significantly better described by a model with two values of central tendency (bimodality), rather than a model with only one (unimodality). Thus, while Packard suggests sigmoid allometries as alternatives to male dimorphism, we argue that such allometries are manifestations of mechanisms that generate bimodal distributions. Instead of focusing on this dichotomy, we propose an approach to test whether bimodality in a trait simply arises from its allometry by: (1) characterizing the trait static allometry, (2) simulating body size values based on original data parameters, and (3) generating new trait sizes using the static allometries. The percentage of simulations generating equal or greater bimodality than the data represents the likelihood that the bimodality can be explained by the allometry alone. Our method offers a null model linking sigmoid allometries and bimodal distributions, providing a test for mechanisms that accentuate trait bimodality beyond what the trait allometry generates.

Poison frogs of the superfamily Dendrobatoidea have fascinated researchers since the 19th century, which is reflected in multiple studies on their natural history, taxonomy, toxicity, colour pattern diversity, and elaborate territorial, reproductive and parental care behaviours. Broadly speaking, however, the term “poison frogs” may apply as well to other taxa which also possess skin toxins. Hereon, we refer to poison frogs as this extended group involving, besides Dendrobatoidea (Dendrobatidae + Aromobatidae), a few genera in families such as Bufonidae and Mantellidae (among others). Most studies on poison frogs have focused on species considered charismatic due to their bright and flashy colours, limiting possible generalisations of patterns and mechanisms explaining the high morphological, ecological, and behavioural differentiation, but also convergence, among these groups. Furthering our understanding of the evolutionary ecology of poison frogs requires increasing not only the scope and depth of our own questions, but also the number and diversity of study systems. Inspired by the special issue on dendrobatid and aromobatid poison frogs published ten years ago in this same journal, we have put together the present special issue aiming to broaden both the topics and the coverage of poison frog clades. This first part consists of 15 manuscripts covering topics ranging from larval behavioural ecology and parental care to space use and its environmental determinants, along with conservation implications.