Sexual Selection and Mixed Sex Expression: Adolescent Protandry, Phenotypic Tradeoffs and ‘Unconventional\u27 Sex Allocation Estimates in a Protandric-Simultaneous Hermaphrodite

In protandric-simultaneous (PS) hermaphrodites, individuals invariably reproduce as males first and later in life as simultaneous hermaphrodites. In this study, the shrimp Lysmata wurdemanni (Gibbes, 1850) was used as a model to (i) test for the role of sexual selection (male-male competition) in explaining the early male phase and size-dependent sex allocation (SDSA) in PS hermaphrodites, (ii) examine the tradeoff between the male and female function in hermaphrodites, and (iii) determine if SDSA also takes place in the form of sex-specific behaviors and anatomical structures. In L. wurdemanni, male mating ability was size- and sex-dependent; greater for small than for large hermaphrodites and for males than hermaphrodites matched in body size. The above explains the adaptive value of the early male phase in PS hermaphrodites; small individuals should speed up sperm production and delay female reproduction to profit from male mating opportunities that are the greatest when small. Size-dependent male mating ability also suggests that small hermaphrodites should produce proportionally more sperm than ova compared to large hermaphrodites, a prediction supported by data. Sex allocation, measured as sex-specific behaviors and anatomical structures, was also size-dependent. No tradeoff between ova and sperm mass was found. However, among-individual variation in resource acquisition was considerable, suggesting that the observed lack of a statistical relationship between sperm and ova mass does not necessarily imply the absence of sex allocation tradeoffs in L. wurdemanni. Sexual selection is most relevant in PS hermaphrodites, SDSA also involves sex-specific behaviors, and morphological features, and variation in resource acquisition and allocation can explain the apparent absence of sex allocation tradeoffs

Static locality analysis for cache management

Most memory references in numerical codes correspond to array references whose indices are affine functions of surrounding loop indices. These array references follow a regular predictable memory pattern that can be analysed at compile time. This analysis can provide valuable information like the locality exhibited by the program, which can be used to implement more intelligent caching strategy. In this paper we propose a static locality analysis oriented to the management of data caches. We show that previous proposals on locality analysis are not appropriate when the proposals have a high conflict miss ratio. This paper examines those proposals by introducing a compile-time interference analysis that significantly improve the performance of them. We first show how this analysis can be used to characterize the dynamic locality properties of numerical codes. This evaluation show for instance that a large percentage of references exhibit any type of locality. This motivates the use of a dual data cache, which has a module specialized to exploit temporal locality, and a selective cache respectively. Then, the performance provided by these two cache organizations is evaluated. In both organizations, the static locality analysis is responsible for tagging each memory instruction accordingly to the particular type(s) of locality that it exhibits.Peer ReviewedPostprint (published version

Testing the Role of Male-Male Competition in the Evolution of Sexual Dimorphism: A Comparison Between Two Species of Porcelain Crabs

Theory predicts marked sexual dimorphism in terms of body size and body structures used as weapons (e.g. chelipeds) in gonochoric species with intense male sexual competition for receptive females and reduced or no sexual dimorphism in species where competition among males is trivial. We tested this hypothesis using a pair of closely-related species of symbiotic porcelain crabs as a model. In one species that inhabits sea anemones solitarily, competition among males for receptive females is unimportant. In a second species that dwells as dense aggregations on sea urchins, malemale competition for sexual partners is recurrent. We expected considerable sexual dimorphism in body size and weaponry in the urchin-dwelling crab and reduced sexual dimorphism in the anemone-dwelling crab. In agreement with expectations, in the urchin-dwelling crab, male body size was, on average, larger than that of females and males invested considerably more to cheliped length than females. Also supporting theoretical considerations, in the anemone-dwelling crab, sexual dimorphism in terms of body size was not detected and differences between the sexes in investment to cheliped length were minor. Interestingly, chelipeds were more developed both in males and females of the anemone-dwelling crab than in the urchin-dwelling crab as a result of the importance of these structures for monopolization of their naturally scarce anemone hosts. Another difference between the studied species was the existence of two clearly distinguishable ontogenetic phases in males of the urchin-dwelling crab but not in males of the anemone-dwelling crab. Whether the two different male morphs display different male reproductive strategies in the urchin-dwelling crab remains to be addressed. Other conditions that might additionally explain the observed differences in sexual dimorphism (e.g. female mate choice) between the studied species remain to be explored. © 2011 The Linnean Society of London

Protandric Simultaneous Hermaphroditism in Parhippolyte Misticia (Clark, 1989) (Caridea: Hippolytidae): Implications for the Evolution of Mixed Sexual Systems in Shrimp

The sexual system of the shrimp Parhippolyte misticia (Clark, 1989), inhabiting the rocky subtidal at Okinawa, Japan and Kimbe Bay, Papua New Guinea, was examined. Dissections suggested that the population consisted of male phase (MP) and functional simultaneous euhermaphrodite (EH) individuals. MPs have cincinulli and appendices masculinae on the first and second pair of pleopods, respectively, gonopores located at the coxae of the third pair of walking legs, and ovotestes with a well-developed male portion containing sperm, but an undeveloped female portion. EHs lacked appendices masculinae and cincinulli. However, they have male gonopores and ovotestes with well-developed ovaries containing mature oocytes and testes with sperm. When EHs were maintained in pairs, both shrimp molted and spawned eggs which attached below the pleon and developed as embryos, demonstrating that EHs can reproduce as males and inseminate other Elis acting as females. These results demonstrate that P misticia is a protandric simultaneous hermaphrodite, as reported before for other shrimp of the genera Lysmata and Exhippolysmata. Also, these results suggest that protandric simultaneous hermaphroditism might have evolved more than once independently in shrimp from the diverse and species-rich Infraorder Caridea. Future research aimed at disentangling the phylogenetic relationship of Parhippolyte, Lysmata, Exhippolysmata and other closely related genera (Calliasmata, Lysmatella, Barbouria) and describing the sociobiology of additional representatives from the genera above is needed to understand the evolutionary history of sexual systems in caridean shrimp. © The Crustacean Society, 2012

Reproductive performance of the marine green porcelain crab \u3ci\u3ePetrolisthes armatus\u3c/i\u3e Gibbes, 1850 in its introduced range favors further range expansion

Invasive marine crustaceans can exhibit population-level variation in reproductive traits that are consistent with a response to stressful conditions near the range edge, or alternatively, that may favor establishing new exotic populations. Reproductive characteristics of the green porcelain crab Petrolisthes armatus Gibbes, 1850 were not previously known in its invasive range in the Atlantic waters of the southeastern USA. We compared fecundity estimates, size at sexual maturity, and various other morphological aspects among crabs collected from two sites at each of four locations spanning approximately 230 km from North Inlet, South Carolina (SC), to Savannah, Georgia (GA), USA. Reproductive output and smallest ovigerous female sizes within the invaded range also were compared to those in the native range, which extends from the Gulf of Mexico and the Caribbean to Brazil in the Western Atlantic Ocean. Reproductive output and egg number were higher and female size at maturity was smaller for crabs from more northern locations (North Inlet and Charleston, SC). Crabs were sexually dimorphic, but population-level differences in overall morphology (e.g., dimensions of the carapace, chelipeds, and secondary sexual characteristics) were not evident in two populations examined (North Inlet, SC, and Bluffton, SC). Secondary sexual characteristics (i.e., abdomen length, abdomen width and pleopod length) contributed the most to the morphological differences between males and females. Using allometric methods, size at sexual maturity was estimated to be 3.99 mm carapace width (CW) for males at North Inlet and 2.96 mm CW for males at Bluffton. Minimum sizes of ovigerous females at our study sites were smaller (3.0 mm to 4.2 mm CW) than a published value for a native population (4.0 mm CW). Reproductive output also was higher in the introduced range (0.05–0.11) than in native populations (0.03–0.07). Along a latitudinal gradient at the northern extent of the invaded range, females allocated more energy to producing offspring at range-edge locations. These results indicate that both within the introduced range and compared to the native range, P. armatus exhibits considerable variation in reproductive performance, which may have assisted in the species′ successful invasion and may aid the species in continuing its range expansion

Reproductive Biology and Recruitment of Xiphopenaeus kroyeri in a Marine Protected Area in the Western Atlantic: Implications for Resource Management

The potential of a recently established marine protected area (MPA) in the Western Atlantic, Brazil, as a \u27seed production\u27 and nursery ground for Xiphopenaeus kroyeri, an intensively exploited penaeid shrimp, was investigated in an attempt to reveal any future benefit of this new MPA to adjacent populations experiencing heavy exploitation. Overall, we observed that males and females \u3e12 and 20 mm carapace length, respectively, contributed the most to reproduction in the studied population. Reproductive activity of X. kroyeri was continuous at the MPA; 2 annual reproductive peaks were recorded from March to April and from November to December, which were followed by recruitment events occurring from March to April 2009 and November 2009. Sediment, temperature, and algae and plant biomass floating near the bottom were relevant in driving reproductive activity and recruitment in X. kroyeri. The high reproductive potential of the studied population and the occurrence of abundant juveniles throughout the sampling area, indicating the existence of a nursery ground within the region, suggest that this MPA might provide important benefits in the near future. We argue in favor of future long-term studies on the larval dispersion, reproductive biology and ecology of X. kroyeri in MPAs and non-MPAs to construct a base for future management of this species and to aid stock recovery in fishing areas that are heavily exploited

Unresolved taxonomy confounds invasive species identification: the Lysmata vittata Stimpson, 1860 (Decapoda: Caridea: Lysmatidae) species complex and recent introduction of Lysmata vittata sensu stricto in the western Atlantic

Peppermint shrimp resembling Lysmata vittata Stimpson, 1860, a species native to the Indo- West Pacific, were found in the lower Chesapeake Bay and adjacent coastal embayments in 2013, representing the first recorded introduction of this species in the northwestern Atlantic. Conflicting morphological descriptions, inconsistent morphological terminology, and limited molecular data (i.e., unresolved taxonomy), as well as the destruction of the type material of L. vittata, created uncertainty regarding proper identification. We provide the first phylogeny incorporating individuals from across the presumed native and introduced range of L. vittata. Morphological and phylogenetic analyses clearly indicate L. vittata represents a species complex of two widely divergent groups: 1) “Bruce Type” with a uniramous dorsal antennule that agrees with A.J. Bruce’s 1990 redescription of L. vittata, and 2) “Rauli Type” with a one-article accessory branch on the dorsal antennule that agrees most closely with the junior synonym L. rauli Laubenheimer & Rhyne, 2010. Given the taxonomic ambiguity surrounding L. vittata, we designate the individual used by A.J. Bruce to redescribe L. vittata and incorporated in our analyses as a neotype to fix the identity of this species. We therefore identify introduced North American and New Zealand populations as L. vittata sensu stricto and postulate that the native range spans temperate/subtropical East Asia. These data suggest that L. rauli is a valid species, which includes a possible undescribed sister species. We confirm the presence of L. californica Stimpson, 1866 in New Zealand, the first non-native record for this species. We also provide data suggesting L. dispar Hayashi, 2007 may be more widespread in the Indo-West Pacific than currently known and consider L. lipkei Okuno & Fiedler, 2010 to be a likely junior synonym

Caesium-137 and Strontium-90 temporal series in the Tagus River: experimental results and a modelling study

The objective of this work consisted of analysing the spatial and temporal evolution of two radionuclide concentrations in the Tagus River. Time-series analysis techniques and numerical modelling have been used in this study. 137Cs and 90Sr concentrations have been measured from 1994 to 1999 at several sampling points in Spain and Portugal. These radionuclides have been introduced into the river by the liquid releases from several nuclear power plants in Spain, as well as from global fallout. Time-series analysis techniques have allowed the determination of radionuclide transit times along the river, and have also pointed out the existence of temporal cycles of radionuclide concentrations at some sampling points, which are attributed to water management in the reservoirs placed along the Tagus River. A stochastic dispersion model, in which transport with water, radioactive decay and wateresediment interactions are solved through Monte Carlo methods, has been developed. Model results are, in general, in reasonable agreement with measurements. The model has finally been applied to the calculation of mean ages of radioactive content in water and sediments in each reservoir. This kind of model can be a very useful tool to support the decision-making process after an eventual emergency situation.Junta de Extremadura 2PR02A02

Ontogenetic Shifts in Resource Allocation: Colour Change and Allometric Growth of Defensive and Reproductive Structures in the Caribbean Spiny Lobster Panulirus argus

Resource allocation theory predicts a disproportionately large allocation of resources to defensive structures during early ontogeny in organisms that are subject to more intense predation at smaller than at larger body sizes. We tested this prediction on the Caribbean spiny lobster Panulirus argus, which exhibits a negative relationship between predation risk and body size with a high natural mortality of smaller individuals. Independent allometric growth analyses demonstrated that numerous defensive structures (e.g. orbital horns, segments supporting the antenna, the tail fan) display negative allometric growth throughout ontogeny. We interpret these findings as lobsters investing disproportionately more resources to defensive structures when small to improve survivorship. Similarly, we observed an ontogenetic shift in lobster colour pattern; small individuals (\u3c23mm carapace length) that inhabit nursery grounds (preferably among red algae) displayed a disruptive pattern (camouflage), whereas larger juveniles displayed a bicolour pigmentation typical of adult lobsters. This shift in colour pattern further suggests that small lobsters employ cryptic coloration throughout their asocial algal stage. However, this cryptic coloration offers no advantage when lobsters grow larger and start dwelling in crevices. Other structures linked to reproduction (e.g. female pleopods and male pereopods) experienced either isometric or positive allometric growth throughout ontogeny. Our results support one of the main predictions of resource allocation theory and demonstrate ontogenetic shifts in defensive structures and coloration concomitantly with changes in lobster mortality risk mediated by size-dependent predation risk. © 2012 The Linnean Society of Londo

Parasitic castration in slipper limpets infested by the symbiotic crab Calyptraeotheres garthi

Two ill-explored hypotheses might explain host castration by parasitic pea crabs. The ‘energy drain’ hypothesis states that castration is caused by host-derived nutrient consumption of parasites that ultimately diminishes host-energy intake. The ‘steric interference’ hypothesis states that castration occurs when parasites physically inhibit host reproduction. This study evaluated whether Calyptraeotheres garthi, a pea crab from the southwestern Atlantic, is a parasitic castrator and explored whether the two hypotheses above explain castration in the limpet Crepidula cachimilla. None of three studied limpet species brooded embryos during the reproductive season when infested by mature female pea crabs. Also, limpets of C. cachimilla infested by C. garthi did not reproduce during a 90-day experimental period while crab-free limpets did spawn embryos during this period. Limpets resumed reproduction soon after pea crabs were experimentally removed from their brooding chamber. Thus, C. garthi does castrate limpets, and castration is reversible. Pea crabs ‘steal’ food from limpets, and infested limpets did not modify their feeding behavior to counteract nutrient loss. Thus, infested limpets are expected to ingest less food which provides partial support for the ‘energy drain’ hypothesis. However, the limpet’s body condition increased or was not affected by pea crabs during the breeding season which argues against the same hypothesis. Furthermore, that limpets promptly recovered reproductive activity once pea crabs were experimentally removed, that castration was not induced by the smallest pea crabs in the population (that fill only partially the brooding chamber), and that parasitized limpets did exhibit fully mature ovaries, support the ‘steric interference’ hypothesis explaining parasitic castration.Fil: Ocampo, Emiliano Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Nuñez, Jesus Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Cledón, Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Baeza, J. Antonio. Universidad Católica del Norte. Coquimbo; Chile. Smithsonian Marine Station at Fort Pierce; Estados Unido