Comparison of contemporary mating patterns in continuous and fragmented Eucalyptus globulus native forests

While habitat fragmentation is a central issue in forest conservation studies in the face of broad-scale anthropogenic changes to the environment, its effects on contemporary mating patterns remain controversial. This is partly because of the inherent variation in mating patterns which may exist within species and the fact that few studies have replication at the landscape level. To study the effect of forest fragmentation on contemporary mating patterns, including effective pollen dispersal, we compared four native populations of the Australian forest tree, Eucalyptus globulus . We used six microsatellite markers to genotype 1289 open-pollinated offspring from paired fragmented and continuous populations on the island of Tasmania and in Victoria on mainland Australia. The mating patterns in the two continuous populations were similar, despite large differences in population density. In contrast, the two fragmented populations were variable and idiosyncratic in their mating patterns, particularly in their pollen dispersal kernels. The continuous populations showed relatively high outcrossing rates (86–89%) and low correlated paternity (0.03–0.06) compared with the fragmented populations (65–79% and 0.12–0.20 respectively). A greater proportion of trees contributed to reproduction in the fragmented ( de/d ≥ 0.5) compared with the continuous populations ( de/d  =   0.03–0.04). Despite significant inbreeding in the offspring of the fragmented populations, there was little evidence of loss of genetic diversity. It is argued that enhanced medium- and long-distance dispersal in fragmented landscapes may act to partly buffer the remnant populations from the negative effects of inbreeding and drift.     

Diurnal changes and frequency dependence in male mating preference for female morphs in the damselfly Ischnura senegalensis (Rambur) (Odonata: Coenagrionidae)

Ischnura senegalensis females exhibit color dimorphism, consisting of an andromorph and a gynomorph, which might be maintained under a frequency-dependent process of mating harassment by mate-searching males. Males change their mating preference for female morph depending on prior copulation experience. Binary choice experiments between two female morphs were carried out in four local populations in the early morning (07.00–09.00 hours) and the afternoon (12.00–14.00 hours), times which mark the onset and the end of diurnal mating activity, respectively. According to the line census along the water's edge, the proportion of andromorphs in the female population varied from 21 to 67% throughout the survey period for four local populations. Males showed non-biased preference for female morphs in the early morning in each local population, while they chose the common morph in the afternoon. Male mating preference for female morphs was positively correlated to the proportion of female morphs in the population. If the selective mating attacks on the common female morphs inhibit their foraging and/or oviposition behavior, frequency-dependent male mating attacks might provide a selective force for maintaining the female color dimorphism in I. senegalensis .     

Differential anatomical responses to elevated CO2 in saplings of four hardwood species

To determine whether an elevated carbon dioxide concentration ([CO₂]) can induce changes in the wood structure and stem radial growth in forest trees, we investigated the anatomical features of conduit cells and cambial activity in 4‐year‐old saplings of four deciduous broadleaved tree species – two ring‐porous (Quercus mongolica and Kalopanax septemlobus) and two diffuse‐porous species (Betula maximowicziana and Acer mono) – grown for three growing seasons in a free‐air CO₂ enrichment system. Elevated [CO₂] had no effects on vessels, growth and physiological traits of Q. mongolica, whereas tree height, photosynthesis and vessel area tended to increase in K. septemlobus. No effects of [CO₂] on growth, physiological traits and vessels were seen in the two diffuse‐porous woods. Elevated [CO₂] increased larger vessels in all species, except B. maximowicziana and number of cambial cells in two ring‐porous species. Our results showed that the vessel anatomy and radial stem growth of Q. mongolica, B. maximowicziana and A. mono were not affected by elevated [CO₂], although vessel size frequency and cambial activity in Q. mongolica were altered. In contrast, changes in vessel anatomy and cambial activity were induced by elevated [CO₂] in K. septemlobus. The different responses to elevated [CO₂] suggest that the sensitivity of forest trees to CO₂ is species dependent.     

Isolation and characterization of microsatellite loci from Quercus mongolica var. crispula

Microsatellites were isolated and characterized for the Japanese oak species, Quercus mongolica var. crispula, distributed in temperate deciduous forests of Japan. Eleven of the 48 primer pairs designed successfully amplified unambiguous and polymorphic single loci among 67 Q. mongolica var. crispula individuals within a plot in southwestern Japan. The observed and expected heterozygosities of the 11 microsatellite markers ranged from 0.522 to 0.896 and from 0.536 to 0.882, respectively. These polymorphic microsatellite markers are useful for estimating pollen‐mediated gene flow in Q. mongolica var. crispula.     

INDIVIDUAL VARIATION IN THE DISTRIBUTION OF LENS POTENCY IN WOLFFIAN LENS REGENERATION

After lentectomy in newts, lens regeneration originates from the iris. The regenerant was externally observed with a stereomicroscope as a depigmented area (DA) of the iris, and the extent of DA up to 15 days after lentectomy was measured. The extent of DA was found to differ among individuals, whereas it was the same in both eyes of each animal. In a number of animals one eye was used for lentectomy. After measuring the DA, two groups of animals were selected; a "W-group" with an extremely wide DA that deviated from the standard value, and "N-group", with an extremely narrow DA. Six iris sectors obtained from the animals of the W-group or N-group were implanted into lentectomized eyes of other animals to investigate the difference in the distribution of lens potency in these two groups. Animals of the W-group possessed a wider distribution of lens potency than animals of the N-group. Pulse-labelling with ³H-thymidine on lentectomized eyes of both groups was done 0, 3, 5, 7 and 12 days after lentectomy. DNA-synthesis began earlier and continued longer in the dorsal part of the iris of the W-group than in that of the N-group. The distribution of lens potency in the iris is discussed on the basis of these findings.     

DIFFERENTIATION AND DEDIFFERENTIATION OF RAT LENS EPITHELIAL CELLS IN SHORT- AND LONG-TERM CULTURES

The crystallin synthesis of rat lens cells in cell culture systems was studied in relevance to their terminal differentiation into lens fibers. SDS-gel electrophoresis combined with several immunological techniques showed that γ-crystallin is a fiber-specific lens protein and is not localized in the epithelium of either newborn or adult lenses. When lens epithelial cells of newborn rats were cultured in vitro , α-crystaIlin was detected in many, but not all, of cells cultured for 10 days. Cells with α-crystallin gradually changed their shape into a flattened filmy form and finally differentiated into lentoid bodies. The differentiation of lentoid bodies was also found in cultures of epithelial cells obtained from adult lenses. The molecular constitution of lentoid bodies was the same as that of lens fibers in situ . The differentiation of lentoid bodies occurred successively for 5 months in cultures of lens epithelial cells. Most of the proliferating cells, however, lost α-crystallin during the culture period. Thereafter, they did not show any sign of further differentiation into lens fibers. Four clonal lines were established from these cells. One protein which is specific to the lens epithelium and the neural retina in situ (tentatively named as β_u-crystallin) was maintained in all lines, suggesting that some specific properties of ocular cells remain in the lined cells.     

Self or Non--self Recognition in Compound Ascidians

SYNOPSIS. Certain species of compound ascidians have an abilityto distinguish self colonies from non—self colonies withinthe same species. This ability, called colony specificity, ismanifested by the fusibility between colonies. The fusibilityamong colonies of Japanese Botryllus is genetically controlledby a series of multiple alleles at a single locus. The fusibilityis determined by a factor(s) in blood, so that the fusibilitycan be altered by the exchange of blood. It is suggested thatrejection, called "nonfusion" reaction, may occur from the interactionbetween blood cells and blood humoral factor(s).