Interspecific Agonistic Interactions Research Articles

Why Were Zebras Not Domesticated? A Review of Domesticability Traits and Tests of Their Role in Ungulate Domestications with Macroevolutionary Models.

Since Darwin, many evolutionary and behavioral researchers have considered the role of phenotypic traits that favor the domestication of nonhuman animals. Among such proposed traits are a species' social structure, level of intra- and interspecific agonistic interactions, sociosexual behaviors, parental strategies, reaction to humans, habitat preference, dietary habits, developmental trajectories, and utility to humans. However, little to no comparative phylogenetic evidence exists concerning the importance of these attributes for the domestication of animals. Moreover, rather than considering domestication as a dichotomous event (non-domesticated vs. domesticated), humans and their potential domesticates encountered numerous socioecological challenges/obstacles during the domestication process before reaching the stage of full domestication. The present study explored the influence of adult body mass, gregariousness, dietary breadth, and reaction to humans on the domestication process of ungulates. The phylogenetic comparative model revealed that capture myopathy (CM), as a proxy for reaction to humans, negatively and significantly influenced the domestication process. The present paper also explored the evolution of CM in equine species in response to the presence of large carnivoran predators during the Pleistocene. Ecologies that preserved most of the large carnivoran predators of equine species also featured more equine taxa with CM (e.g., zebras), which were thus less suitable for domestication.

Morphological Differences in the Island-Endemic Hawaiian Subspecies of the Common Gallinule Gallinula galeata

The study of island subspecies provides excellent “natural experiments” for examining the impacts of different selective regimes on animal taxa. We examined the morphological differences between the Hawaiian and continental North American subspecies of the Common Gallinule (Gallinula galeata sandvicensis and G. g. cachinnans, respectively), for which the existing literature is both scant and contradictory. More than 200 live gallinules and >100 museum specimens were measured, and a meta-analysis of literature values on North American Common Gallinules was conducted to quantitatively assess differences in wing chord, culmen and tarsus length, and body mass between these subspecies. Hawaiian Common Gallinules had smaller wing chords (–2.5 to –4.0%), larger culmen (+4.5 to +7.0%) and tarsi (+5.5 to +23.0%), and slightly larger body masses (∼+4.0%) than their mainland conspecifics. This is likely due to several factors including reduced predation pressure, shorter dispersal distances, nonmigratory behavior, and sedentary lifestyles associated with ecological differences between the Hawaiian Islands and the North American mainland. We also introduce the novel hypothesis that intra- and interspecific agonistic interactions due to habitat limitation are an additional selective force in driving these morphological changes.

Force and Boldness: Cumulative Assets of a Successful Crayfish Invader

Multiple causes can determine the disturbance of natural equilibrium in a population of a species, with a common one being the presence of invasive competitors. Invasives can drive native species to the resettlement of the trophic position, changing reproduction strategies or even daily normal behaviours. Here, we investigated the hypothesis that more effective anatomical features of an intruder (Faxonius limosus) come with increased boldness behaviour, contributing to their invasion success in competition against the native species (Pontastacus leptodactylus). We tested the boldness of specimens representing the two species by video-based assessment of crayfish individuals’ attempts to leave their settlement microenvironment. The experiment was followed by a series of measurements concerning chelae biometry, force and muscle energetics. The native species was less expressive in terms of boldness even if it had larger chelae and better muscular tissue performance. In contrast, because of better biomechanical construction of the chelae, the invasive species was capable of twice superior force achievements, which expectedly explained its bolder behaviour. These findings suggest that, in interspecific agonistic interactions, the behaviour strategy of the invasive crayfish species is based on sheer physical superiority, whereas the native crayfish relies on intimidation display.

An avian dominance hierarchy at a supplemental water source in the Patagonian steppe.

Birds often compete and engage in interspecific agonistic interactions for access to resources such as food and breeding territories. Based on the observed outcomes from such interactions (i.e., patterns of displacements) dominance hierarchies can be established. Knowing which species can outcompete others for essential resources allows researchers to make predictions about the broader ecological impacts of interspecific interactions. We constructed an interspecific dominance hierarchy of twelve avian species which visited an artificial water source in an arid region of coastal Patagonia, Argentina. Displacements were categorized into four types, based on the behaviors involved in the interaction, and we tested if they could predict the difference in dominance between the interacting species (the difference between calculated dominance coefficients for the two focal species). Indirect displacements, involving only the arrival of the dominant species to the water source without direct aggression toward the subordinate bird, occurred more frequently between species with a large difference in dominance. The most dominant bird observed was the kelp gull (Larus dominicanus), which, due to an increasing population and expanding range, in part due to food supplementation from fisheries waste, is likely to outcompete terrestrial and marine avian species for other scarce resources.

Towards a functional understanding of species coexistence: ecomorphological variation in relation to whole‐organism performance in two sympatric lizards

SummaryWe examined intra‐ and interspecific variation in functional morphology and whole‐organism performance in a sympatric lizard species pair,Iberolacerta horvathiandPodarcis muralis, in the area with a high potential for competition.The biggest variation between species was found in two functional traits, bite force and climbing speed, linked with corresponding morphological traits.The species with larger and taller heads,P. muralis, exhibited correspondingly stronger bite forces. The other species exhibited smaller and flatter head. Both traits may potentially promote segregation between species in trophic niche (stronger bites relate to harder prey) and in refuge use (flatter heads allow using narrower crevices, hence, influencing escaping from common predators). Stronger bites and larger heads also provide one species with a dominant position in interspecific agonistic interactions.Females had longer trunks that impacted negatively on climbing speed, which may lower anti‐predator escape abilities of the more trunk‐dimorphic species, but positively influence reproductive effort.Our results exemplify how the joint examination of morphological and functional traits of ecologically similar and sympatric species can provide a mechanistic background for understanding their coexistence, namely, syntopic populations that are frequent in the study area.The identified roles of functional morphology in this system of sympatric rock lizards support the contribution of functional diversification for the complexity of community structure via coexistence.Alay summaryis available for this article.

Who bullies whom at a garden feeder? Interspecific agonistic interactions of small passerines during a cold winter

Interspecific agonistic interactions are important selective factors for maintaining ecological niches of different species, but their outcome is difficult to predict a priori. Here, we examined the direction and intensity of interspecific interactions in an assemblage of small passerines at a garden feeder, focussing on three finch species of various body sizes. We found that large and medium-sized birds usually initiated and won agonistic interactions with smaller species. Also, the frequency of fights increased with decreasing differences in body size between the participants. Finally, the probability of engaging in a fight increased with the number of birds at the feeder.

Habitat associations and behavioural patterns of Symphodus spp. (Pisces: Labridae)

The complexity and diversity of physical and biotic habitats are important features influencing the composition of shallow water reef fish assemblages, especially in temperate regions where abundant and diverse algal cover may have an important habitat-forming role. Coastal fish have adapted to these diverse habitats and to the temporal and spatial variations of algal assemblages in different ways. Wrasses are an important group of coastal rocky reef fish which present particular associations to algae in temperate systems. In this study, habitat associations were analysed in three species of wrasses: Symphodus bailloni, Symphodus melops and Symphodus roissali, and their behaviour was recorded. Eight main behavioural categories (comprising a total of 42 different behaviours) were identified: exploring, foraging, resting, agonistic interactions, cleaning, courtship, reproduction and nesting. S. melops occurred on shallower depths and was frequently involved in both intra- and interspecific agonistic interactions with the other wrasse species, although rarely with S. bailloni. S. roissali was associated with microhabitats of smaller size where it frequently hides. Feeding occurred mostly on bedrock habitat when compared to other microhabitats. Foraging and resting showed a marked seasonality in the three wrasses, related to shifts in biotic habitat structure and to changes in the behavioural repertoire during the breeding season.

Correlation of Cere Color with Intra- and Interspecific Agonistic Interactions of Crested Caracaras

Bright coloration in birds is an important indicator of individual quality often used in social displays. Structural, carotenoid-, and melanin-based colors are long-lasting, widespread, and widely studied. Hemoglobin-based colors are ephemeral, rare, and less studied. Hemoglobin-based displays occur when an individual facultatively enhances or restricts blood flow through caruncles, combs, wattles, or other highly vascularized un-feathered skin patches. In Crested Caracaras (Caracara cheriway; hereafter “caracara”) highly vascularized ceres facultatively undergo immediately reversible hemoglobin-based color changes, hypothesized to correlate with status during contests. I predicted aggressors in contests would consistently display hemoglobin-deprived ceres (hereafter “light”), and receivers would display hemoglobin-enhanced ceres (hereafter “dark”), or vice versa. To test this hypothesis, I conducted 149 30-min group observations during which I recorded outcomes of all observed intra- and interspecific agonistic interactions involving caracaras in groups including up to 46 caracaras (x¯ = 13.4, SD = 6.9). I recorded 2586 agonistic interactions in which I could identify cere colors and ages of both caracaras involved in an intraspecific interaction (n = 1160), or of one caracara involved in an interspecific interaction (n = 1426). Cere colors of caracaras were consistently light when acting as aggressors in intra- and interspecific agonistic interactions, and dark when acting as receivers. Within age classes, caracaras displaying light-colored ceres were consistently aggressors toward caracaras displaying dark ceres, and between age classes, adults with light-colored ceres were aggressors toward younger birds with dark ceres. Caracaras displaying light-colored ceres were aggressors toward Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura) and caracaras with dark ceres were receivers of aggression from these species. Regardless of the cere color, caracaras were subordinate to much larger Bald Eagles (Haliaeetus leucocephalus) and dominant over much smaller American Crows (Corvus brachyrhynchos). My observations support the hypothesis that cere color is correlated with agonistic behaviors and support the signaling hypothesis by correlating specific cere colors displayed with individual roles in intra- and interspecific interactions.En las aves, la coloración brillante es un indicador importante de calidad individual que se usa a menudo en los despliegues sociales. Los colores estructurales y basados en carotenoides y melanina han sido estudiados desde hace tiempo y de forma amplia y generalizada. Los colores basados en la hemoglobina son efímeros, raros y menos estudiados. Los despliegues basados en la hemoglobina ocurren cuando un individuo aumenta o restringe facultativamente el flujo sanguíneo a través de las carúnculas, crestas u otros parches de piel sin plumas altamente vascularizados. En Caracara cheriway, las ceras altamente vascularizadas experimentan de forma facultativa cambios de color inmediatamente reversibles basados en la hemoglobina, los cuales se piensa que están correlacionados con el estatus durante las competencias. Predije que en una competencia, los individuos agresores desplegarían consistentemente ceras carentes de hemoglobina (de aquí en más “claras”) y que los individuos que reciben la agresión desplegarían ceras realzadas por la hemoglobina (de aquí en más “oscuras”) o viceversa. Para evaluar esta hipótesis, realicé 149 observaciones grupales de 20 minutos cada una durante las cuales registré los resultados de todas las interacciones agonísticas intra e inter-específicas observadas que involucraban a ejemplares de C. cheriway en grupos de hasta 46 individuos (x¯ = 13.4, DE = 6.9). Registré 2586 interacciones agonísticas en las cuales pude identificar el color de la cera y las edades de ambos individuos involucrados en una interacción intra-específica (n = 1160), o de u

Comparative Spring-Staging Ecology of Sympatric Arctic-Nesting Geese in South-Central Nebraska

The Rainwater Basin in Nebraska has been a historic staging area for midcontinent greater white-fronted geese (Anser albifrons frontalis) since the 1950s and, in the mid-1990s, millions of midcontinent lesser snow geese (Chen caerulescens caerulescens) expanded their spring migration route to include this region. In response to speculation that snow geese may be in direct competition with white-fronted geese, we compared staging ecology by quantifying diet, habitat use, movement patterns, and time budgets during springs 1998–1999. Collected white-fronted geese (n = 190) and snow geese (n = 203) consumed primarily corn (Zea mays; 97–98% aggregate dry mass) while staging in Nebraska; thus, diet overlap was nearly complete. Both species used cornfields most frequently during the morning (54–55%) and wetlands more during the afternoon (51–65%). When found grouped together, snow goose abundance was greater than white-fronted goose abundance by an average of 57 times (se = 11, n = 131 groups) in crop fields and 28 times (se = 9, n = 84 groups) in wetlands. Snow geese and white-fronted geese flew similar distances between roosting and feeding sites, leaving and returning to wetland roost sties at similar times in mornings and afternoons. Overlap in habitat-specific time budgets was high; resting was the most common behavior on wetlands, and foraging was a common behavior in fields. We observed 111 interspecific agonistic interactions while observing white-fronted and snow geese. White-fronted geese initiated and dominated more interactions with other waterfowl species than did snow geese (32 vs. 14%). Certain aspects of spring-staging niches (i.e., diet, habitat use, movement patterns, and habitat-specific behavior) of white-fronted and snow geese overlapped greatly at this mid-latitude staging site, creating opportunity for potential food- and habitat-based competition between species. Snow geese did not consistently dominate interactions with white-fronted geese; yet large differences in their numbers coupled with high degrees of spatial, temporal, and ecological overlap support potential for exploitative competition during years when waste corn may be in short supply and dry years when few wetlands are available for staging waterfowl.

Relative Growth and Its Use to Determine the Morphological Sexual Maturity of Ucides Cordatus (Linnaeus, 1763) (Decapoda, Brachyura, Ucididae) from Two Mangrove Areas on the Northeastern Brazilian Coast

AbstractThe study of relative growth was used to determine the dimensions that best demonstrate the morphological sexual maturity of Ucides cordatus from two mangrove areas (Ariquindá and Mamucabas) of the southern coast of the state of Pernambuco, northeast Brazil. The crabs were collected manually, with a capture effort by one person, during low tide in three different areas (each 25 m2) during a period of one year from April 2008 to March 2009. Crabs of both sexes were measured for the following dimensions: carapace width (CW); carapace length (CL); major cheliped propodus length (CPL); major cheliped propodus height (CPH); abdomen width (AW) and gonopod length (GL). These variables were subjected to an analysis of K-means clustering followed by a bivariate discriminant analysis, which separated the data into two groups: juveniles and adults. After separation of the groups, each age category was grouped into sixteen size classes of CW and the proportion of adults in each size class was calculated, and fitted to a logistic equation. Subsequently, an interpolation was performed to determine the size at which 50% of the males and females were mature. The relationships that best demonstrated the size at maturity were CPL vs. CW for males (Positive allometry; Ariquindá — juveniles b = 1.27, adults b = 1.41; Mamucabas — juveniles b =1.27, adults b = 1.44) and AW vs. CW for females (Positive allometry; Ariquindá — juveniles b = 1.34, adults b = 1.28; Mamucabas — juveniles b = 1.32, adults b = 1.44). The present analysis indicates that, for these same relationships, 50% of males and females are morphologically mature, at, respectively, 38.0 and 35.4 mm CW in Ariquindá, and 37.3 and 32.9 mm CW in Mamucabas. Positive allometry shown in the female abdomen is related to egg incubation, and the excessive growth observed in the male cheliped must be related to reproductive behaviour, including courtship and intra- or inter-specific agonistic interactions with other males.

Use of cover habitat by bull trout, Salvelinus confluentus, and lake trout, Salvelinus namaycush, in a laboratory environment

Lacustrine-adfluvial bull trout, Salvelinus confluentus, migrate from spawning and rearing streams to lacustrine environments as early as age 0. Within lacustrine environments, cover habitat provides refuge from potential predators and is a resource that is competed for if limiting. Competitive interactions between bull trout and other species could result in bull trout being displaced from cover habitat, and bull trout may lack evolutionary adaptations to compete with introduced species, such as lake trout, Salvelinus namaycush. A laboratory experiment was performed to examine habitat use and interactions for cover by juvenile (i.e., <80 mm total length) bull trout and lake trout. Differences were observed between bull trout and lake trout in the proportion of time using cover (F1,22.6 = 20.08, P < 0.001) and bottom (F1,23.7 = 37.01, P < 0.001) habitat, with bull trout using cover and bottom habitats more than lake trout. Habitat selection ratios indicated that bull trout avoided water column habitat in the presence of lake trout and that lake trout avoided bottom habitat. Intraspecific and interspecific agonistic interactions were infrequent, but approximately 10 times greater for intraspecific interactions between lake trout. Results from this study provide little evidence that juvenile bull trout and lake trout compete for cover, and that species-specific differences in habitat use and selection likely result in habitat partitioning between these species.

A comparative field study of the social behavior and related ecology of reef fishes of the family Chaetodontidae1)2).

20 Species of Chaetodontidae were observed in the field for a total of about 150 hrs at Eniwetok Atoll in the Marshall Islands, at Heron Island on the Great Barrier Reef, and at Johnson Island. During observations the diver either stayed in one place for 30 min, swam transects or followed individual fish. Social groupings of the different species, their intra- and interspecific agonistic interactions and their feeding are described. The frequent occurrence of Chaetodontidae in pairs and the relatively low observed level of agonistic encounters are discussed.

Population structure of six sympatric species of Trapezia associated with the hermatypic coral Pociliopora damicornis with a hypothesis of mechanisms promoting their coexistence

Seasonal changes in species composition and size frequency distributions of six sympatric coexisting species of Trapezia associated with the hermatypic coral Pociliopora damicornis were investigated to analyze their population structure, mechanisms promoting coexistence, and the organizing processes of the symbiont community. All Trapezia species showed a long recruitment season, but they could be divided into two groups according to variations in their size frequency distribution pattern throughout the year: Young T. ferruginea and T. guttata occurred all year round, while young T. cymodoce, T. areolata, T. digitalis, and T. sp. were absent part of the time (a few months). Recruitment of T. cymodoce and T. areolata occurred from April to August and from February to March, respectively. Young T. digitalis were abundant only in July. Even among larger colonies, those harboring only one or two Trapezia species were rather common. This suggests that agonistic interactions occur among these crab species. Although it is also true that host colonies harboring several species are sometimes found. Since no conspicuous hierarchy in inter-specific agonistic interactions has been demonstrated (Tsuchiya and Yonaha, 1992), new crab recruits of any species can invade colonies lacking strong competitors.Although these crab species require very similar resources, i. e. pocilloporid corals as their habitat and mucus produced by host corals as food, their coexistence on larger single colonies is promoted by several mechanisms: 1) different recruitment seasons, 2) weak hierarchy of agonistic interactions among the six species, and 3) microhabitat segregation between adults and young on a colony.

Distribution, abundance, and interspecific agonistic behavior of two mudflat stomatopods.

Two species of stomatopod (Fam: Squillidae) were sampled on an intertidal mudflat at Ang Sila on the Gulf of Thailand. In 25 transects each of 23 m2 we collected 219 Cloridopsis scorpio and 49 Oratosquilla inornata. In interspecific agonistic interactions, both in an open arena and with one animal defending a burrow, C. scorpio dominated O. inornata; in the burrow defense study, C. scorpio drove O. inornata out of a burrow on 8 of 11 occasions while O. inornata failed to drive C. scorpio out of burrows. In the field both species increased in numbers simultaneously on a per transect basis and both were also more numerous closer to shore indicating a degree of microhabitat overlap. Gut analyses indicated some dietary similarity. C. scorpio digs a longer and more complex burrow. Differences in abundance increased as numbers of C. scorpio increased suggesting that C. scorpio, where it is abundant, tends to exclude O. inornata; in areas where O. inornata was most numerous, individuals of this species were large and therefore presumably more successful in agonistic interactions. The evidence suggests that C. scorpio is the more abundant on the Ang Sila mudflat because it competes more successfully via agonistic behavior; sufficient resource overlap seems to exist for competition to occur thus conferring an advantage on the more aggressive species.