Karyological studies on Spanish Boraginaceae. VI. Contribution to the tribe Eritrichieae

LUQUE, T., 1992. Karyological studies on Spanish Boraginaceae. VI. Contribution to the tribe Eritrichieae. Karyological information is presented for c. 15 taxa of the genera Asperugo L., Rochelia Reichenb., Myosotis L. and Lappula Gilib. This paper is the first in this series of karyological studies of Spanish Boraginaceae to deal with Eritrichieae.     

Biogeography of Iberian freshwater fishes revisited: the roles of historical versus contemporary constraints

Aim The question of how much of the shared geographical distribution of biota is due to environmental vs. historical constraints remains unanswered. The aim of this paper is to disentangle the contribution of historical vs. contemporary factors to the distribution of freshwater fish species. In addition, it illustrates how quantifying the contribution of each type of factor improves the classification of biogeographical provinces. Location Iberian Peninsula, south‐western Europe (c. 581,000 km²). Methods We used the most comprehensive data on native fish distributions for the Iberian Peninsula, compiled from Portuguese and Spanish sources on a 20‐km grid‐cell resolution. Overall, 58 species were analysed after being categorized into three groups according to their ability to disperse through saltwater: (1) species strictly intolerant of saltwater (primary species); (2) species partially tolerant of saltwater, making limited incursions into saltwaters (secondary species); and (3) saltwater‐tolerant species that migrate back and forth from sea to freshwaters or have invaded freshwaters recently (peripheral species). Distance‐based multivariate analyses were used to test the role of historical (basin formation) vs. contemporary environmental (climate) conditions in explaining current patterns of native fish assemblage composition. Cluster analyses were performed to explore species co‐occurrence patterns and redefine biogeographical provinces based on the distributions of fishes. Results River basin boundaries were better at segregating species composition for all species groups than contemporary climate variables. This historical signal was especially evident for primary and secondary freshwater fishes. Eleven biogeographical provinces were delineated. Basins flowing to the Atlantic Ocean north of the Tagus Basin and those flowing to the Mediterranean Sea north of the Mijares Basin were the most dissimilar group. Primary and secondary freshwater species had higher province fidelity than peripheral species. Main conclusions The results support the hypothesis that historical factors exert greater constraints on native freshwater fish assemblages in the Iberian Peninsula than do current environmental factors. After examining patterns of assemblage variation across space, as evidenced by the biogeographical provinces, we discuss the likely dispersal and speciation events that underlie these patterns.     

Reproductive activity and physiological status of the calanoid copepods Calanus helgolandicus and Calanoides carinatus under food-limiting conditions

The reproductive activity and the physiological state of the calanoid copepods Calanus helgolandicus and Calanoides carinatus were investigated off the coast of NW Spain during autumn to evaluate the effect of short food resources on both populations. Phytoplankton biomass was low, and neither phytoplankton size distribution nor composition was suitable to support high reproductive rates. Accordingly, egg production rates (EPR) were much lower than maximum rates for both species, pointing to food limitation. The reproductive index (RI), which represents the proportion of females with mature gonads, was < 50% at each of the three zones into which the sampling area was divided (coast, shelf and ocean). Potential recruitment rates were very low except at some nearshore stations, where the highest concentrations of chlorophyll-a (Chl-a), diatoms, dinoflagellates and large cells were found. EPR of C. helgolandicus and C. carinatus were correlated with phytoplankton biomass and unaffected by temperature. Phytoplankton carbon ingestion explained ca. 50% of the variability in EPR for both species. At most of the stations, herbivory was insufficient to cover the carbon requirements for reproduction and respiration, so females probably fed on heterotrophic prey to meet their demands. However, given the low fecundity observed, this omnivorous diet did not seem to be optimum for reproduction, and a severe food limitation is thus suggested. Furthermore, the high C/N values measured point to a notable lipid storage, but given the low EPR found, lipid reserves were probably invested into female maintenance rather than into gonad maturation. C. helgolandicus and C. carinatus populations did not mirror phytoplankton biomass distribution, but they correlated well when considering only copepodites V (CV). The CV could be preparing for the overwintering, storing lipid reserves to ensure a successful diapause, and they could also be advected by the poleward current detected during the study. Females showed a diel feeding rhythm, with highest ingestion rates during night. From our results, it follows that C. helgolandicus and C. carinatus females did not perform diel vertical migrations. We suggest that this behaviour is likely due to the food-limiting conditions, which make it more advantageous to remain at the surface during daytime.     

The structure of 180° supernumerary limbs and a hypothesis of their formation

The results of a detailed analysis of 100 supernumerary limbs generated by 180° ipsilateral rotation (on the same limb stump) of regeneration blastemas is presented. The limbs were analyzed in terms of their position of origin, frequency, cartilage structure by Victoria blue staining, and muscle structure by serial sections. Single, double, or triple supernumeraries can be produced at no unique position of origin, although the posterodorsal quadrant was preferred. Four classes of supernumerary limbs were generated by such operations—normal; double dorsal or double ventral; part normal/part mirror imaged; part normal/part inverted in approximately equal frequencies. After amputation of these supernumeraries the same muscle patterns are faithfully regenerated. A hypothesis to explain the production of these abnormal limbs is proposed based on the observed phenomenon of fusion of supernumerary blastemata, but their regenerative behaviour presents problems for current models of pattern formation. Similar results have been obtained with developing limb buds and the relation between development and regeneration is discussed.     

Multilocus and morphological analysis of south-eastern Iberian Wall lizards (Squamata,Podarcis)

The phylogenetic relationships among the wall lizards of the Podarcis hispanicus complex that inhabit the south-east (SE) of the Iberian Peninsula and other lineages of the complex remain unclear. In this study, four mitochondrial and two nuclear markers were used to study genetic relationships within this complex. The phylogenetic analyses based on mtDNA gene trees constructed with ML and BI, and a species tree using *BEAST support three divergent clades in this region: the Valencia, Galera and Albacete/Murcia lineages. These three lineages were also corroborated in species delimitation analyses based on mtDNA using bPTP, mPTP, GMYC, ABGD and BAPS. Bayesian inference species delimitation method (BPP) based on both nuclear data and a combined data set (mtDNA + nuclear) showed high posterior probabilities for these three SE lineages (≥0.94) and another Bayesian analysis (STACEY) based on combined data set recovered the same three groups in this region. Divergence time dating of the species tree provided an estimated divergence of the Galera lineage from the other SE group (Podarcis vaucheri, (Albacete/Murcia, Valencia)) at 12.48 Ma. During this period, the Betic–Rifian arc was isolated, which could have caused the isolation of the Galera form distributed to the south of the Betic Corridor. Although lizards from the Albacete/Murcia and Galera lineage are morphologically similar, they clearly represent distinct genetic lineages. The noteworthy separation of the Galera lineage enables us to conclude that this lineage must be considered as a new full species.     

Temporal patterns of breeding and recruitment in Nerophis lumbriciformis(Pisces; Syngnathidae) related to seawater temperatures

The breeding season of Nerophis lumbriciformis , a cold water pipefish, was positively correlated with seawater temperatures <15·5° C, whilst recruitment occurred at the end of the upwelling season, when seawater temperature attained its maximum values. The observed alterations in seawater temperatures, with steady year‐round increases, and the consequent alteration of the upwelling regime, may have dramatic consequences in the maintenance of N. lumbriciformis populations, by reducing the breeding period and simultaneously contributing to the transport of pelagic larvae northwards due to specific sea currents that occur outside the upwelling season.     

Influence of environment upon the life history of gudgeon, Gobio gobio (L.): a recent and successful colonizer of the Iberian Peninsula

The growth and the reproductive tactics of gudgeon, Gobio gobio (L.) were assessed in three contrasting streams of the Iberian Peninsula: the Rivers Moros and Ucero, tributaries of the R. Duero, and the R. MatarrańGa, a tributary of the R. Ebro. The R. Duero gudgeon have spread in the last 50 years while their presence in the lower tributaries of the R. Ebro followed the construction of reservoirs in the mid 1960s. The life histories of the Moros and MatarrańnGa gudgeon are very similar; rapid growth in spring, early reproduction (1 -year-old), high reproductive cost, short life-span and trend to semelparity. Both populations are strongly influenced by the severe summer droughts that result in (I) reduction in the condition coefficient, (2) reduction in the growth rate (particularly in the River MatarrańGa), (3) single spawning and (4) no gonad development in the summer. The gudgeon in the Ucero delay maturity, grow slower, are multi-spawners and have a longer life span. All the Duero populations come from the same genetic pool and they are actually connected through the populations living along this river basin, whereas the MatarrańGa population is not genetically linked, we hypothesize that the differences between these populations are environmentally induced.     

New ecological information onScytalina cerdale (Pisces: Scytalinidae) from a central California rocky intertidal zone

Synopsis New information regarding the ecology ofScytalina cerdale was obtained over a four year period as a consequence of a long-term marine ecological study at the Diablo Canyon Power Plant (DCPP), San Luis Obispo County, California. Twenty intertidal fish surveys were conducted at approximately quarterly intervals, between March 1979 and June 1983, at three separate rocky shore locations (stations). During each survey, a total of 108 square meters (36 m² per station) was searched for fish during periods of low tide. A total of 280S. cerdale were collected, identified, measured, and released back into the same 4 m² area, from the same intertidal station (Diablo Cove), throughout the study period. This limited intertidal occurrence most likely reflectsS. cerdale microhabitat requirements; a combination of intertidal elevation (mean = +0.3 MLLW), substratum specificity (loose gravel, 5–10mm size range, overlying a base of sand and shell fragments), and degree of wave exposure (semi-protected). Throughout the study,S. cerdale was seasonally more abundant during summer months (June through August) and less abundant during winter months (November through February). The only exception to this abundance trend followed the 1982 winter storms, which coincided with an El Niño event, whenS. cerdale abundance uncharacteristically dropped during the subsequent 1983 spring and summer surveys. Mean total lengths did not vary greatly, reflecting the absence of early juvenile fishes, and relatively high mean fish densities (3.5 fish per m² for 20 surveys) were recorded. Qualitative comparisons betweenS. cerdale abundance and seasonal changes in water temperature indicated an inverse relationship. Gravid females, demersal egg masses, and early juvenile individuals were never observed during the four years of the study. This suggests that unlike most other intertidal fishes, particularly other blennioids,S. cerdale may not utilize the intertidal zone for reproductive and recruitment purposes; Diablo Canyon is the most southerly reported distribution for this intertidal species, and therefore, may not entirely represent the species' biology as a whole.     

The effect of vitamin A on limb regeneration in Rana temporaria

Previous experiments in which vitamin A has been administered to developing or regenerating limbs have shown that different limb axes are affected. In regenerating axolotl limbs, serial reduplications in the proximodistal axis are produced. In the developing chick limb bud, mirror-imaged reduplications in the anteroposterior axis are produced. Results reported here on Rana temporaria limb buds reveal that vitamin A causes both effects to occur. That is, limbs are both serially reduplicated in the proximodistal axis and mirror imaged in the anteroposterior axis. Time and concentration effects are explored and the significance of these results for our current understanding of axial organisation in limbs is discussed.     

Numerical modelling of large-scale circulation in Lakes Onega and Ladoga

The results of numerical modelling of large-scale circulation in Lakes Onega and Ladoga are presented, with primary emphasis on the temporal variability of currents with time scales of days. Some typical circulation patterns have been inferred from model calculations. They reflect the existence of different dynamic regimes in the lakes, namely, forced and free circulation regimes. The forced circulation regime is the well-known wind-induced double-gyre circulation accompanied by coastal upwelling and downwelling. A case of double-gyre circulation in Lake Onega was investigated in particular detail. The second dynamic regime is a free response (or a relaxation) of the stratified lake to wind cessation, and is connected closely with the evolution of wind-induced upwelling and thermal front propagation. Diagnostic calculations demonstrate that the regime of relaxation supports the restoration of cyclonic circulation in Lake Onega. Barotropic circulation patterns in Lake Ladoga were calculated with the emphasis on prevailing winds from west to south-east. Our calculations show that the bottom relief of Lake Ladoga causes asymmetry in the double-gyre circulation patterns. In particular, approximately equal cyclonic and anticyclonic circulation cells appearing in the case of southerly wind transform to a single dominant cyclonic cell and several small anticyclonic cells in the case of westerly wind. We also found especially strong sensitivity of the sense of rotation of the largest gyre to the east-west components of the wind vector.