Marksizam i fenomenologija na XIV Internacionalnom kongresu za filozofiju

Squid behavior is synonymous with distinctive body patterns, postures, and movements that constitute a complex visual communication system. These communications are particularly obvious during reproduction. They are important for sexual selection and have been identified as a potential means of species differentiation. Here we present a detailed account of copulation, mating, and egg deposition behaviors from in situ observations of the squid Sepioteuthis australis from South Australia. We identified four mating types from 85 separate mating attempts: “Male-upturned mating” (64% of mating attempts); “Sneaker mating” (33%); “Male-parallel” (2%); and “Head-to-head” (1%). Intervals between successive egg deposition behaviors were clearly bimodal, with modes at 2.5 s and 70.0 s. Ninety-three percent of egg capsules contained 3 or 4 eggs (mean = 3.54), and each egg cluster contained between 218 and 1922 egg capsules (mean = 893.9). The reproductive behavior of S. australis from South Australia was different from that described for other cephalopod species. More importantly, comparison between these results and those for other populations of S. australis suggests that behavior may differ from one population to another

Importance of plasticity and local adaptation for coping with changing salinity in coastal areas: a test case with barnacles in the Baltic Sea

Background:Salinity plays an important role in shaping coastal marine communities. Near-future climate predictions indicate that salinity will decrease in many shallow coastal areas due to increased precipitation; however, few studies have addressed this issue. The ability of ecosystems to cope with future changes will depend on species’ capacities to acclimatise or adapt to new environmental conditions. Here, we investigated the effects of a strong salinity gradient (the Baltic Sea system – Baltic, Kattegat, Skagerrak) on plasticity and adaptations in the euryhaline barnacle Balanus improvisus. We used a common-garden approach, where multiple batches of newly settled barnacles from each of three different geographical areas along the Skagerrak-Baltic salinity gradient were exposed to corresponding native salinities (6, 15 and 30 PSU), and phenotypic traits including mortality, growth, shell strength, condition index and reproductive maturity were recorded.ResultsWe found that B. improvisus was highly euryhaline, but had highest growth and reproductive maturity at intermediate salinities. We also found that low salinity had negative effects on other fitness-related traits including initial growth and shell strength, although mortality was also lowest in low salinity. Overall, differences between populations in most measured traits were weak, indicating little local adaptation to salinity. Nonetheless, we observed some population-specific responses – notably that populations from high salinity grew stronger shells in their native salinity compared to the other populations, possibly indicating adaptation to differences in local predation pressure.ConclusionsOur study shows that B. improvisus is an example of a true brackish-water species, and that plastic responses are more likely than evolutionary tracking in coping with future changes in coastal salinity

Indiscriminate Males: Mating Behaviour of a Marine Snail Compromised by a Sexual Conflict?

Background: In promiscuous species, male fitness is expected to increase with repeated matings in an open-ended fashion (thereby increasing number of partners or probability of paternity) whereas female fitness should level out at some optimal number of copulations when direct and indirect benefits still outweigh the costs of courtship and copulation. After this fitness peak, additional copulations would incur female fitness costs and be under opposing selection. Hence, a sexual conflict over mating frequency may evolve in species where females are forced to engage in costly matings. Under such circumstance, if females could avoid male detection, significant fitness benefits from such avoidance strategies would be predicted. Methodology/Principal Findings: Among four Littorina species, one lives at very much higher densities and has a longer mating season than the other three species. Using video records of snail behaviour in a laboratory arena we show that males of the low-density species discriminate among male and female mucous trails, trailing females for copulations. In the high-density species, however, males fail to discriminate between male and female trails, not because males are unable to identify female trails (which we show using heterospecific females), but because females do not, as the other species, add a gender-specific cue to their trail. Conclusions/Significance: We conclude that there is likely a sexual conflict over mating frequency in the high-densit

THE ECOLOGY AND BEHAVIOR OF NAUTILUS-POMPILIUS IN THE PHILIPPINES

Volume: 15Start Page: 75End Page: 8

Individual variability in reproductive success determines winners and losers under ocean acidification : a case study with sea urchins

Background: Climate change will lead to intense selection on many organisms, particularly during susceptible early life stages. To date, most studies on the likely biotic effects of climate change have focused on the mean responses of pooled groups of animals. Consequently, the extent to which inter-individual variation mediates different selection responses has not been tested. Investigating this variation is important, since some individuals may be preadapted to future climate scenarios. Methodology/Principal Findings: We examined the effect of CO2-induced pH changes ("ocean acidification") in sperm swimming behaviour on the fertilization success of the Australasian sea urchin Heliocidaris erythrogramma, focusing on the responses of separate individuals and pairs. Acidification significantly decreased the proportion of motile sperm but had no effect on sperm swimming speed. Subsequent fertilization experiments showed strong inter-individual variation in responses to ocean acidification, ranging from a 44% decrease to a 14% increase in fertilization success. This was partly explained by the significant relationship between decreases in percent sperm motility and fertilization success at ΔpH = 0.3, but not at ΔpH = 0.5. Conclusions and Significance: The effects of ocean acidification on reproductive success varied markedly between individuals. Our results suggest that some individuals will exhibit enhanced fertilization success in acidified oceans, supporting the concept of 'winners' and 'losers' of climate change at an individual level. If these differences are heritable it is likely that ocean acidification will lead to selection against susceptible phenotypes as well as to rapid fixation of alleles that allow reproduction under more acidic conditions. This selection may ameliorate the biotic effects of climate change if taxa have sufficient extant genetic variation upon which selection can act.8 page(s

Physiological ecology of Adalaria proxima (Alder et Hancock) and Onchidoris muricata (Müller) (Gastropoda:Nudibranchia). II. Reproduction

The nudibranch molluscs Adalaria proxima and Onchidoris muricata are semelparous annuals. Although these species are ecologically, morphologically, and taxonomically similar, their reproductive characteristics differ markedly. In the present study, A. proxima individuals generally attained a larger size and commenced spawning later in the spring than O. muricata. The total energy invested in spawn production by A. proxima individuals was ≈ 1.5 times that for O. muricata, however, A. proxima produced this in fewer spawn masses and over a shorter spawning period. Correspondingly, the mean energy content of A. proxima spawn masses was greater (≈ 3 times) than that of O. muricata spawn. Nonetheless, the "average" A. proxima spawn mass contained only an estimated 675 ova in comparison to the 3300 ova in an "average" O. muricata spawn mass. This difference was due to the contrasting larval types exhibited by these species. A. proxima produces large well-provisioned ova which hatch as pelagic lecithotrophic veligers, whereas O. muricata ova are relatively small and develop into long-term planktotrophic larvae. Individuals of both species were observed to undergo degrowth throughout their spawning periods, but total production (soma plus cumulative spawn) continued to rise at a rate equal to, or slightly greater than, prespawning growth rate. Overall production patterns showed considerable intraspecific consistency, but differed between species. Degrowth rate (per day) for A. proxima was in excess ofthat for O. muricata, however, all individuals died after ≈33% of the maximum somatic weight had been lost.</p

Physiological ecology of Adalaria proxima (Alder et Hancock) and Onchidoris muricata (Müller) (Gastropoda:Nudibranchia). III. Energy budgets

Gross energy budgets are presented for (immature) juvenile and (reproducing) adult stages of the nudibranch molluscs Adalaria proximo (Alder et Hancock) and Onchidoris muricata (Müller). Measurements of growth, respiration and reproduction in seven individuals of each species are compared and contrasted with estimates of consumption. Assimilation efficiencies of both species were low compared with those for other species of gastropod. Respiratory costs for reproducing A. proximo were approximately equal to those for juveniles of both species, however, a significant decline in respiratory cost was observed between the juvenile and adult stages of O. muricata. This was reflected in the net reproductive efficiency which was accordingly greater in O. muricata than in A. proximo. On a daily basis, somatic tissue degrowth was of greater importance in maximising the reproductive output of A. proximo than of O. muricata. Degrowth contributed almost 19% of the daily energy flux to reproduction in A. proximo whereas the equivalent value for O. muricata was only 8%. A significant correlation was obtained between spawning rate and juvenile growth rate in O. muricata. No such association was observed for A. proximo although adult degrowth rate was closely (but not significantly) correlated with spawn production rate. These patterns are discussed with reference to the evolution of different larval types in these species.</p

Reproductive Behavior in the Squid Sepioteuthis australis From South Australia: Ethogram of Reproductive Body Patterns

Volume: 204Start Page: 290End Page: 30

Physiological ecology of Adalaria proxima (Alder et Hancock) and Onchidoris muricata (Müller) (Gastropoda:Nudibranchia). I. Freeding, growth, and respiration

The nudibranch molluscs Adalaria proxima (Alder et Hancock) and Onchidoris muricata (Müller) are annual, semelparous, simultaneous hermaphrodites which are largely sympatric and preferentially graze the same bryozoan Electro pilosa (L.). Ecologically, morphologically, and taxonomically, these species are similar, however, they reproduce by means of contrasting larval types: O. muricata has long-term planktotrophic larvae and A. proxima has short-term pelagic lecithotrophic larvae. The present paper is the first of a series which aims to analyse these contrasting larval types within the context of detailed dynamic energy budgets. Here we present data on the rates of feeding, prespawning growth, and respiration for laboratoryheld "populations" of both species. Nudibranchs were collected from the field as juveniles and maintained at near-ambient (not constant) temperatures. For both O. muricata and A. proximo feeding rate displayed an asymptotic increase with body size. Both the observed mean and (fitted) estimates of feeding rates for A. proxima exceeded those for comparable-sized O. muricata. Correspondingly, A. proxima individuals demonstrated greater somatic growth rates, and attained greater maximum body sizes than did O. muricata. Furthermore, growth of A. proxima was approximately linear whilst that of O. muricata followed an increasing curvilinear pattern. Respiration rates were relatively constant within any given individual, however significant differences between individuals were observed for both species. O. muricata individuals displayed a more rapid increase in respiratory rate with increasing body size than did A. proxima. Respiration rates of either species were not significantly affected by (seasonal) flucuations in water temperatures, with the exception of A. proxima individuals during the spawning period.</p