Staining protocols affect use of otolith to estimate the demography of the damselfish sergeant major (Abudefduf vaigiensis)

This study assessed the otolith (sagittae, lapilli, and asterisci) increment deposition rate in the range-shifting damselfish, A. vaigiensis, using different concentrations of Alizain Red S and evaluated the impact of staining on increment width. Daily increment deposition was verified in all otolith types and presented clearer fluorescent markings in the lapilli and sagittae than the asterisci, with high stain concentration showing the best clarity. Higher stain concentrations were found to decrease increment width, suggesting care is needed when using stained otoliths as a proxy for growth for this species.     

Reproductive behavior of the sergeant major,Abudefduf saxatilis,within a closed system aquarium

Synopsis The reproductive and social biology of the sergeant major,Abudefduf saxatilis, was studied for six months in The Living Seas aquarium (the largest aquarium ever constructed). The purpose of the study was to discern possible behavioral differences between captive and wild breeding populations of this species. A total of 350 h of observation were obtained using closed circuit SCUBA, open circuit SCUBA, and remote operated vehicles. Slight differences were observed in the behavior of individuals in the sample population and those seen in wild populations. These differences may be due to the effects of a controlled closed system on the biology of these fishes.     

Small-scale genetic connectivity of bicolor damselfish (Stegastes partitus) recruits in Mexican Caribbean reefs

The analysis of genetic similarities among marine populations is a key method for use in connectivity studies intended to provide information for management strategies. The present study aimed at assessing the connectivity levels of subpopulations of bicolor damselfish (Stegastes partitus) recruits at a small scale (~200 km) among four reefs in the Mexican Caribbean. Samples were collected from 13 sites nested in two Marine Parks (Cozumel and Xcalak), one Biosphere Reserve (Chinchorro Bank) and one unprotected area (Mahahual). A total of 713 samples were genetically characterized by means of seven microsatellite DNA markers and were analyzed on a hierarchical basis. A strong genetic structure was detected among sites with a weak but significant genetic structure among reefs, the combination of which has not been reported in previous studies. These results appear to be related to a “sweepstake-chance effect” combined with oceanographic factors. An isolation by distance test, in addition to a hierarchical Bayesian method, revealed that neither distance among sites and reefs nor any of 10 environmental factors tested could be used to explain the genetic differences observed. The results suggest that conservation strategies for S. partitus based on local scales are likely to be effective.     

The effect of brood size and age on partial filial cannibalism in the scissortail sergeant

Within the size range found in the field for the scissortail sergeant Abudefduf sexfasciatus , there was no correlation between the number of cannibalized eggs and total brood size. Very small broods were fully cannibalized. In a manipulation experiment, males were provided with broods of one of three standardized sizes: at the two extremes and in the middle of the range of naturally occurring broods. Brood size had no effect on partial filial cannibalism, but parental effort increased with increasing brood size. Field correlates and the manipulation experiment showed that the cost of cannibalism in terms of current reproductive success decreased significantly with increasing brood size. Contrary to expectations, there was no relationship between male size and the incidence of cannibalism. No preference for younger eggs was found either from field correlates or from a manipulative experiment in which males were provided with an equal number of young and old eggs at the beginning of the parental phase.     

Paternity and egg cannibalism in the ringlegged earwig Euborellia annulipes (Dermaptera: Anisolabididae)

Cannibalism is a common occurrence in nature, and many cannibals prey on relatively small and defenseless life stages, such as eggs or young juveniles. Such behavior provides many benefits to the cannibal, but cannibalistic individuals also face risks, including the cost of decreasing their inclusive fitness by eating close relatives such as siblings or offspring. This risk can be mitigated if cannibals can recognize and avoid preying on kin. Here, we tested whether male ringlegged earwigs Euborellia annulipes avoid cannibalizing eggs that they had sired. In this species, females care for their own eggs, but males provide no care and frequently prey upon eggs. We found that when presented with an unguarded clutch of eggs, male earwigs nearly always cannibalized some eggs, but that the proportion of eggs eaten was smaller if the male had sired the clutch. This suggests that males can distinguish between their own offspring and unrelated offspring and that they avoid harming their kin.     

Territorial behaviour of beaugregory damselfish (Stegastes leucostictus) in response to egg predators

To test the hypothesis that territorial male beaugregory damselfish (Stegastes leucostictus) can assess the degree of threat from egg predators, the aggressive behaviour of both males guarding eggs and males without eggs was recorded when they were presented with either one or five individuals of the wrasse egg predator Thalassoma bifasciatum. Presentations were made in a clear plastic bottle 0.5 m from artificial beaugregory breeding sites in the field. Two measures of aggressive behaviour (downhead threats and time spent within 10 cm of the presentation bottle) were significantly greater for multiple wrasse presentations than for single wrasse presentations, while a third measure (chase attempts) was not. In contrast, chase attempts were significantly greater for males guarding eggs than for males without eggs, but there was no significant difference in the level of downhead threats or bottle proximity time for this comparison. Levels of the three aggressive measures were not correlated with either the amount of eggs or the number of egg clutches present. These results indicate that territorial male beaugregories respond to an increase in the number of intruding egg predators by increasing the levels of low-cost threat behaviour, while the presence (but not the amount) of eggs results in an increase in the amount of higher cost attack behaviour. These experiments, therefore, support the hypothesis that male beaugregories can assess the degree of threat from egg predators, and indicate that they use this assessment to alter the strategies used in territorial defence.     

Proximate factors influencing egg cannibalism in the land snail Arianta arbustorum (Pulmonata,Helicidae)

Summary Byttneria aculeata (Sterculiaceae), a subcanopy liane with a shrubby juvenile form has two distinct leaf color morphs in juvenile plants- a given juvenile has plain green leaves or leaves with whitish variegation. Both forms occur together in the forest and in clearings; however, the variegated morph is more common in open sites, and the plain morph predominates in the forest. Percent variegation per leaf for variegated plants increased from closed to open sites. Measurements of growth support the idea that variegation is favored in open habitats. Within a given habitat, rate of herbivory by leaf miners on a given morph increases with increasing relative frequency of that morph; however, at a given relative frequency, the variegated morph is less heavily attacked than is the plain morph when it occurs elsewhere at that same frequency.     

<Emphasis Type="Italic">Abudefduf nigrimargo</Emphasis>, a new species of damselfish (Perciformes: Pomacentridae) from Taiwan

A new species of damselfish, Abudefduf nigrimargo (Pomacentridae), is described on the basis of six specimens (91.8–119.5 mm standard length; SL) from Taiwan. Although similar to A. caudobimaculatus Okada and Ikeda 1939, A. saxatilis (Linnaeus 1758), A. troschelii (Gill 1862) and A. vaigiensis (Quoy and Gaimard 1825) in having five dark bands on the lateral surface of the body with yellowish interspaces dorsally, the new species can be distinguished from the others by the following combination of characters: 18–19 (mode 19) pectoral-fin rays; 20–23 (22) tubed lateral-line scales; 7–8 (7)?+?14–16 (16)?=?21–24 (23) gill rakers; relatively greater body depth and longer pectoral-fin length [57.3–60.8% (mean 59.0%) of SL and 36.8–40.8% (38.5%) of SL, respectively]; 5 scale rows on cheek; scales on suborbit, usually continuous over basal area of lacrimal; many scales on anteroventral region of head; scale covering on preopercle and interopercle continuous; scales on dorsal and lateral body surfaces with blackish margin (indistinct in subadult), second and third black bands on body not extending dorsally onto membranes of spinous dorsal fin; anterior and upper margins of fourth black band usually level with sixth dorsal-fin soft ray base and not extending onto small scales on the dorsal-fin base, respectively; and caudal-fin base without black spots.     

Effect of egg cannibalism on mating preferences and reproductive fitness of Menochilus sexmaculatus Fabricius (Coleoptera: Coccinellidae)

Cannibalism has been reported in a large proportion of coccinellids in fields as well as in laboratories but studies involving mate preferences and potential benefits of cannibalism on reproduction in Menochilus sexmaculatus Fabricius (Coleoptera: Coccinellidae) have yet not been done. Thus, we assessed the effect of conspecific egg cannibalism on mate preferences and reproductive outputs including offspring development. Higher mate preferences were recorded for non-cannibalistic mates (fed on A. craccivora) than cannibalistic ones (fed on conspecific eggs). Mating parameters were significantly influenced by cannibalism. Time to commence mating lasted less for homogeneous diet pairs than heterogeneous diet pairs. Longer copulation duration and higher fecundity were recorded when one of the individuals in mating pair or both was a non-cannibal. Egg viability did not differ significantly in all the reciprocal crosses. In addition, the total developmental durations of offspring were similar for all mating pairs.     

Morphological Differentiation in the Damselfish Abudefduf saxatilis Along the Mexican Atlantic Coast is Associated with Environmental Factors and High Connectivity

Evolutionary Biology - Coastal regions represent environments with heterogenic ecological conditions and with potential barriers to dispersal, making them ideal systems to study the variation of...     

Distribution and Movement Tendencies of Short-Tailed Viper Snakes(Gloydius saxatilis) by Altitude

The distribution pattern of reptiles in mountainous regions is generally related to altitude.The distribution of viperine species can be limited by elevation.Short-tailed viper snakes(Gloydius saxatilis) of South Korea are found mostly in high elevation mountainous areas,but few studies have evaluated how their distribution relates to elevation gradient.This study was conducted from 2012 to 2013 to investigate the altitudinal distribution of short-tailed viper snakes in mountainous areas and to discover their movement patterns in Cheon-ma Mountain County Park in South Korea.A translocation method utilizing radiotracking technology was employed to confirm whether their distribution was influenced by altitude.The results showed that most short-tailed vipers were observed in middle and high altitude areas(from 400 m to 800 m),but none were observed in low altitude areas(from 200 m to 400 m).According to the results of the translocation and tracking experiments,the individuals of the translocated group showed a significantly broader home range than those of the control group.In addition,all individuals of the translocated group moved vertically,while most of the control group moved horizontally.Therefore,all translocated individuals tended to move back toward their original habitat,a high elevation area.Consequently,we concluded that the distribution of short-tailed viper snakes was limited by altitude.     

On the (dis) advantages of cannibalism

Cannibalism is an interaction between individuals that can produce counter- intuitive effects at the population level. A striking effect is that a population may persist under food conditions such that the non-cannibalistic variant is doomed to go extinct. This so-called life boat mechanism has received considerable attention. Implicitly, such studies sometimes suggest, that the life boat mechanism procures an evolutionary advantage to the cannibalistic trait. Here we compare, in the context of a size structured population model, the conditions under which the life boat mechanism works, with those that guarantee, that a cannibalistic mutant can invade successfully under the steady environmental conditions as set by a non-cannibalistic resident. We find qualitative agreement and quantitative difference. In particular, we find that a prerequisite for the life boat mechanism is, that cannibalistic mutants are successful invaders. Roughly speaking, our results show that cannibalism brings advantages to both the individuals and the population when adult food is limiting.     

Interference behavior and ecology of threespot damselfish (Eupomacentrus planifrons)

Summary Interference behavior by threespot damselfish directed at the sea urchins, Diadema antillarum and Echinometra viridis, differed in levels of aggression and discrimination. Higher aggression towards and recognition of Diadema by threespots was correlated with the distribution of Diadema along edges of coral patches. Lower aggression levels combined with lower recognition levels of Echinometra were correlated with a distribution of Echinometra closer to damselfish algal lawns. Differences in behavior of the urchins stimulated differing levels of aggression by the damselfish directly affecting the distribution of the urchins in the back-reef environment.This is contribution number 167 from the Discovery Bay Marine Laboratory of the University of the West Indies, Jamaica     

Parasite transmission and cannibalism in an amphipod (Crustacea)

In its freshwater amphipod host Gammarus duebeni celticus, the microsporidian parasite Pleistophora mulleri showed 23% transmission efficiency when uninfected individuals were fed infected tissue, but 0% transmission by water-borne and coprophagous routes. Cannibalism between unparasitised and parasitised individuals was significantly in favour of the former (37% compared to 0%). In addition, cannibalism between parasitised individuals was significantly higher than between unparasitised individuals (27% compared to 0%). Thus, parasitised individuals were more likely to be cannibalised by both unparasitised and parasitised individuals. We discuss the conflicting selective forces within this host/parasite relationship, the implications of parasite mediated cannibalism for host population structure and the impacts this may have on the wider aquatic community.     

Ladybird egg cluster size: relationships between species, oviposition substrate and cannibalism

The success or not of ladybirds as biological control agents is dependent on both their foraging behaviour and their individual survival rates. The former is a function of the habitats they utilise; the latter, a consequence of their reproductive strategy. Egg clustering was investigated in two ladybird species, Aphidecta obliterata, a conifer specialist, and Adalia bipunctata, an arboreal woodland generalist. The effect of oviposition substrate (filter papers vs. spruce needles) on clutch size and oviposition preference was also tested. Adalia bipunctata laid significantly more eggs than A. obliterata. The size of egg clusters laid by the two coccinellids varied between species and substrate types. Adalia bipunctata laid larger egg clusters than A. obliterata, with batches reaching a maximum size of 32 eggs on spruce and 41 eggs on paper, while those of A. obliterata contained a maximum of 5 eggs on spruce and 9 eggs on paper. Of the clusters laid by A. obliterata, 18.6% of those on paper and 21.4% of those on spruce contained only a single egg, whereas a minimum of two eggs per cluster were laid by A. bipunctata. Smaller clusters were laid on the spruce cuttings by both species when compared with those laid on the filter paper, but A. obliterata laid significantly more eggs on spruce than on the filter paper (77% vs. 23%), whilst A. bipunctata laid significantly more eggs on the filter paper (91%). It is suggested that coccinellid eggs are more likely to be washed off spruce needles than broad leaves and that, by laying smaller egg clusters on spruce, A. obliterata reduces this risk. Adalia bipunctata usually lays its eggs on the underside of broad leaved trees and thus does not face this risk and thus can lay larger egg clusters. No differences in cannibalism rates were found between the two species. These findings have implications for the use of ladybirds as biological control agents in spruce forests.     

In situ settlement behaviour of damselfish (Pomacentridae) larvae

Settlement‐stage damselfish (Pomacentridae) larvae of 13 species in seven genera were obtained from light traps at Lizard Island, Great Barrier Reef, Australia. Behaviour, observed in situ by SCUBA divers, of 245 larvae (6–13 mm, L_S; 5–60 individuals per species) released individually within a few m of reefs during the day differed markedly among species. From 0–28% (range among 13 species) of individuals of each species swam away from the adjacent reefs without swimming to the reefs. Of those that swam to a reef, 0–75% settled. For three species, sufficient data were available to test the hypothesis that these percentages did not differ amongst reefs: the hypothesis was rejected in one species. From 0–75% of larvae that reached the reef were eaten, 0–63% subsequently left the reef and 0–60% were still swimming over the reef at the end of the observation period. Swimming speeds of all but one species were greater when swimming away from the reef than toward it. Most species exceeded average current speeds when swimming away from reefs, but not when swimming toward and over them. Average swimming depths were in the upper half of the water column for most species, and were somewhat greater where the water depths were greater. The time the larvae swam over the reef before settling and the distance swum varied greatly among species from 0 to a mean of 5.5 min and 43 m. Settlement habitats chosen differed amongst species, and in some species, they were very specific. Average settlement depth varied among species from 6–13.5 m. In one species, settlement depth varied between reefs. About half of the 53 observed interactions between larvae and reef resident fishes were predation attempts: fishes of eight species (six families) attacked larvae. The other interactions were aggressive approaches by 11 species of resident fishes, all but one of which were pomacentrids. Many of these aggressive interactions discouraged settlement attempts. Larvae of some species experienced no predatory or aggressive interactions, whereas in other species interactions averaged >0.6 per released larva. Species that swam more‐or‐less directly to settlement sites near the reef edge experienced more interactions. Even within the same family, settlement behaviour differed among species in nearly all measures.