Health-dependent vulnerability to predation affects escape responses of unguarded chinstrap penguin chicks

Predators may select more often to attack the more vulnerable prey or those with an inferior health status. Thus, prey should be able to assess their own vulnerability to predation and modify their antipredatory behavior accordingly. When approached by predator skuas, unguarded penguin chicks flee short distances, and usually aggregate in dense packs, but there is a clear interindividual variability in their responses under similar conditions. We hypothesized that this variability in escape responses might be related to the perceived vulnerability to predation of each individual chick. We simulated predator attacks to chinstrap penguin chicks and analyzed the sources of variation in their escape response, such as the presence of adults or the density of other chicks, and the sex, age, body condition, and health status of responding chicks. Chicks allowed shorter approach distances when they had a better health condition (i.e., a greater T-cell-mediated immunity, CMI), when they were younger, and when the density of adults around was higher. Sex and density of other chicks were not important. Similarly, chicks fled from the experimenter to longer distances when they had a lower CMI and when the density of adults was lower. Therefore, escape characteristics of chicks depended on the presence of adults that can deter predators and on the health-dependent vulnerability of chicks.     

Genome-size variation in bivalve molluscs determined by flow cytometry

Six of the nine described species of the mole crab genus Emerita are distributed in the Americas, two [E. analoga (Stimpson, 1857) and E. rathbunae Schmitt, 1935] on the west coast, and four [E. benedicti Schmitt, 1935, E. brasiliensis Schmitt, 1935, E. portoricensis Schmitt, 1935 and E. talpoida (Say, 1817)] on the east. The presence of an extended planktonic larval stage in all Emerita species suggests high dispersal potential and the possibility of extensive gene flow among conspecific populations. Two taxa were sampled to study the extent of gene flow between widely separated conspecific populations: E. analoga (California and Chile) and E. talpoida (Massachusetts, South Carolina, and the west coast of Florida), while all other taxa were characterized from a single location. Portions of two mitochondrial genes, cytochrome oxidase I (COI) and 16S ribosomal RNA (16S rRNA) were sequenced. For data analysis, approximately 500 bp (COI) and 400 bp (16S rRNA) were examined. Estimated genetic divergence of 5.41% in COI between E. talpoida populations sampled from the Gulf of Mexico and the Atlantic coast, and 3.47% between E. analoga sampled in Chile and California, indicates that in both cases there has been no recent gene flow between disjunct populations. Additional molecular and morphological studies are necessary to decide whether disjunct populations should be accorded specific status. We predict that many marine invertebrates with antitropical distributions similar to E. analoga may consist of sibling species. In contrast to relationships inferred earlier from distribution patterns, parsimony analyses of both COI and 16S rRNA data yield similar phylogenetic trees in which E. analoga is separated from a clade composed of other species in the Americas; a bootstrap value (67%) in the COI inferred tree marginally supports the separation, but the same tree topology with a higher bootstrap value (84%) is obtained with 16S rRNA sequence data. Genetic divergence among the taxa indicates that the Emerita species constitute an old group and that distribution of species has been modified by past climatic and geological events.     

Removal of the herbicide amitrole from water by anodic oxidation and electro-Fenton

Here we demonstrate that an aqueous solution of the herbicide amitrole can be completely depolluted at pH 3.0 by anodic oxidation and electro-Fenton process. Anodic oxidation gives faster degradation with a boron-doped diamond anode than with a Pt anode. Electro-Fenton with a Pt anode and 1 mmol l ^–1 Fe²⁺ as catalyst yields the quickest depollution. Amitrole decay always follows a pseudo first-order reaction. NO₃^– and NH₄⁺ are accumulated in the medium during mineralization, although volatile N-products are also formed. These environmentally friendly electrochemical treatments could be applied to the remediation of wastewaters containing amitrole.     

Regulation of fructose-2,6-bisphosphate content in mantle tissue of the sea musselMytilus galloprovincialis

6-phosphofructo-2-kinase (PFK-2) from the mantle of the sea musselMytilus galloprovincialis Lmk, collected from the Ría de Arosa (NW Spain) in 1990, was purified 550-fold by extraction and sequential affinity chromatography on Affi-gel Blue and ATP-agarose columns. The enzyme was a dimer with a native molecular weight of 100 kilodaltons (KDa) and a subunitM _r of 53 KDa. PFK-2 activity is dependent on the presence of P_i. At physiological P_i concentrations, the enzyme exhibits hyperbolic kinetics with both ATP and Fru-6-P, withK _m values of 0.62 and 0.37 mM respectively. In vivo, PFK-2 activity is limited by the concentration of Fru-6-P which is low in comparison with theK _m for this substrate. Citrate and PEP inhibited PFK-2 activity.     

Chloroacetic acids in environmental processes

The fate of chloroacetic acids (CAA) in forest soils was studied using radio-indicator methods. We showed that chloroacetic acids are both microbially degraded and simultaneously formed by chloroperoxidase-mediated chlorination of acetic and humic acids. The degree of biodegradation of chloroacetic acids in soil depends on their concentration. Dichloroacetic acid (DCA) is degraded faster than trichloroacetic acid (TCA). Chlorination of acetic acid led to a fast formation of dichloroacetic acid, whereas chlorination of humic acids gave rise to trichloroacetic acid. Both processes lead to a steady state in soil, participate in the chlorine cycle and possibly also in decomposition of organic matter in forest ecosystems.     

Desperado siblings: uncontrollably aggressive junior chicks

According to the desperado sibling hypothesis, chicks of obligately siblicidal species kill their junior broodmates as early as possible because junior broodmates face dire ecological prospects and are consequently predisposed to aggressively overthrow elder broodmates by all-out aggression. The agonistic behavior of junior chicks is virtually unknown because they die so young. We investigated the agonistic behavior of hypothetical desperados by fostering junior brown boobies (Sula leucogaster, an obligately siblicidal species) into nests of the blue-footed booby (S. nebouxii, a facultatively siblicidal species) containing an older singleton blue-foot chick. Controls were junior blue-footed boobies fostered into the same situation. Junior brown boobies were 7 times more aggressive than controls and most of them dominated their elder and larger nestmates. Four of nine brown booby juniors showed relentless aggression, delivering up to 711 pecks, bites and pushes (including "expulsion pushes") per hour, thereby overwhelming nestmates 90% heavier and permanently expelling one of them from the nest. Similarly, in natural broods of two surviving brown booby chicks, the losing chick was 13 times as aggressive as blue-foot subordinates, up to at least age 7 weeks. Contrast of the two species of booby suggests the evolution of agonistic roles within broods may be partly driven by selection on potential victims to express a level and type of aggressiveness appropriate to their status-related ecological prospects.     

Quadratic diversity: Its maximization can reduce the richness of species

In recent decades numerous diversity indices have been introduced. Among them the quadratic entropy index Q expresses the mean difference between two individuals chosen from the community at random. Differing from diversity indices habitually employed, Q does not satisfy a property postulated earlier for those measures. Namely, the uniform distribution of species does not necessarily yield the maximal index value. Q is based on the difference matrix of species. For a given matrix one can seek for the vector yielding the maximum quadratic entropy. This task leads to a quadratic programming problem. Using the appropriate program of a program package, we determined the maximum vector for a genetic difference matrix of crane species, as published in the literature. We discovered that some components (frequencies) in the maximum vector are equal to zero. That is, by maximizing the quadratic diversity some species can be eliminated. We discuss briefly the possible implications of this observation. Moreover, even if all elements in the maximum vector are positive, the elements can differ.     

Copulatory plugs do not assure high first male fertilisation success: sperm displacement in a lizard

Sperm competition selects for opposing male defensive and offensive reproductive traits, and its outcome may be determined by the effectiveness to which one trait has evolved to out-compete the other. We tested the effectiveness of a first male plug physical interference with a second male insemination (defence) vs the effectiveness of plug and associated sperm displacement by a second male (offence) on the outcome of sperm competition in Iberian rock lizards. We conducted a double mating experiment where we compared the proportion of eggs per clutch fertilised by the same second males (against the same first males) when they copulated with females 30 min (first male plug adhered firmly inside the female cloaca) and 4 h (first male plug loosely adhered or shed from the female cloaca) after first males. We found that second males fertilised the majority of the eggs per clutch in the 30-min treatment, whereas fertilisations were equally shared between the two males in the 4-h treatment. These results show that plugs have little defensive effectiveness, and thus, do not assure high first male fertilisation success. Instead, sperm displacement appears to be associated with plug displacement. That is, because sperm embedded in first male plugs, and displaced from competition for fertilisations by second males, is expected to increase in number with decreasing time allowed for female sperm transport, second males thus enjoy higher fertilisation success. This study shows that offensive plug displacement out-competes plug defensive role in Iberian rock lizards. Moreover, it reveals sperm displacement as a novel sperm competition mechanism in reptiles.     

Determinants of male territorial behavior in a Hungarian collared flycatcher population: plumage traits of residents and challengers

In intrasexual conflicts, contestants can rely on relative or absolute size of status badges to mediate aggressive behavior. Most studies focus on the response of focal animals to variation in status badges of their competitors; few have simultaneously considered the traits of both participants under experimental conditions. By simulating territorial intrusions, we tested the importance of two sexual traits [forehead patch size (FPS) and wing patch size (WPS)] in territorial behavior of males in a Hungarian population of the collared flycatcher, Ficedula albicollis. We presented a stimulus male to an unpaired resident male to examine whether the characteristics of the territory owner or those of the challenger were associated with the latency of the first attack of the owner, which is a good predictor of the territorial behavior in general. WPS of the stimulus male was a significant determinant of the latency of the first attack, as males with a larger WPS elicited quicker attacks from the residents than males with a small WPS. From the residents’ perspective, age appeared to influence their territorial behavior, as yearlings had shorter attack latencies than older males. Additionally, latency could be considered an individual-specific attribute because it varied consistently among males, even when the WPS of the stimulus male was controlled, and it was associated with pairing success. Contrary to findings in a Swedish population, FPS seemed to be unimportant in male–male competition in our population, which suggests population differences in the role of the two plumage traits. Our results indicate that in a territorial conflict, the characteristics of both participants are important.     

Roles of male residence and relative size in the social behavior of Iberian rock lizards, Lacerta monticola

Many studies on contest competition used residency asymmetry as a discrete variable. However, the probability of winning an interaction may change as a continuous function of the value of the location where the encounter occurs. We performed a field study to examine the importance of location within a home range and relative body size to the outcomes of agonistic interactions between male lizards, Lacerta monticola. The distances to activity centers (the most used locations based on a density function of sightings) and relative size play important roles in agonistic interactions and had interacting effects in natural conditions. On the other hand, previous studies with lizards suggested that inferior competitors are able to avoid agonistic interactions in the field. Thus, we staged encounters in the laboratory to examine the behavioral responses of smaller individuals. The responses of each focal smaller male were measured in its own home cage (resident), in the cage of a larger male (intruder) and in a cage in which no male was previously present (control). The predominant behavioral tactics of smaller males were avoidance when they are the intruders and displaying when they are the residents. Submissive displays by smaller males may help reduce the costs of agonistic encounters.