Summer Nursery Research Articles

Speed-Breeding System in Soybean: Integrating Off-Site Generation Advancement, Fresh Seeding, and Marker-Assisted Selection

Speed breeding by artificial control of photothermal conditions facilitates generation advancement but was limited in scale and cost. In this study, we demonstrated a cost-saving off-site summer nursery pattern, taking full advantage of shorter daylength and higher temperature with lower latitude compared to the origin of the soybean cultivars used in the study. This substantially reduced the generation cycles under totally natural conditions. Using this approach, two generations of soybean cultivars from Northeastern Spring Planting Region (NE) and Yellow-Huai-Hai Valleys Summer Planting Region (YHH) were successfully obtained in Beijing and Hainan, respectively, compared to one generation in origin. Fresh-seeding method was also used to further shorten the generation duration by 7–10 days, thereby allowing at least four generations per year. Using DNA markers to define haplotypes of maturity genes E1–E4, we proposed a model to predict the optimum adaptation region of the advanced generation lines. Taken together, we present a speed-breeding methodology combining off-site nursery, fresh-seeding method, and marker-assisted selection, aimed at accelerating soybean improvement.

Three-Dimensional Movements and Habitat Selection of Young White Sharks (Carcharodon carcharias) Across a Temperate Continental Shelf Ecosystem

As highly mobile predators with extensive home ranges, some shark species often utilize a continuum of habitats across the continental shelf ranging from the surf zone to the open ocean. For many species, these cross-shelf distributions can change depending on ontogeny or seasonal conditions. Recent research has confirmed a white shark (Carcharodon carcharias) summer nursery off Long Island, New York; however, habitat characterization of this nursery has not yet been conducted nor has fine-scale analysis of vertical behavior. Between 2016 and 2019, 21 young-of-the-year and juvenile white sharks were fitted with satellite and acoustic tags to examine distribution and selection for a suite of oceanographic variables during their late summertime (i.e., August to October) residence in the New York Bight. Horizontal position estimates were used to extract a suite of environmental measurements via remote sensing platforms and were linked with vertical profiles to produce three-dimensional movements for a subset of individuals also fitted with pop-up satellite archival tags (n = 7). Sharks exhibited horizontal movements parallel to Long Island’s southern shoreline and coastal New Jersey, with distances from 0.1 to 131.5 km from shore. Log-likelihood chi-square analyses determined selection for waters with underlying bathymetry of 20–30 m, sea surface temperatures between 20.0 and 22.0°C, sea surface salinities between 31.0 and 32.0 ppt, and chlorophyll-a concentrations between 2.0 and 8.0 mg⋅m–3. Multiple individuals also traversed the mid- to outer shelf region after leaving the Montauk tagging area. Vertical depth profiles illustrated oscillations between the surface and 199 m of water, with an average swimming depth of 9.2 ± 8.9 m. Water column temperatures during these oscillations ranged between 7.9 and 26.2°C (mean = 19.5 ± 2.0°C) with several individuals traversing highly stratified regions presumably associated with a mid-shelf cold pool adjacent to the Hudson Shelf Valley. These results suggest young white sharks exhibit connectivity between the immediate shoreline and mid-continental shelf region, where they play important ecological roles as predators on a variety of species. Our study improves characterization of essential fish habitat for young white sharks and provides new insights into their reliance on this productive continental shelf ecosystem.

Response of Water Chemistry and Young-of-Year Brook Trout to Channel and Watershed Liming in Streams Showing Lagging Recovery from Acidic Deposition

Reductions in sulfur emissions have initiated chemical recovery of surface waters impacted by acidic deposition in the Adirondack region of New York State. However, acidified streams remain common in the region, which limits recovery of brook trout (Salvelinus fontinalis) populations. To investigate liming as a method to accelerate recovery of brook trout, the channels of two acidified streams were limed annually from 2012 to 2015, and an entire watershed of a third acidified tributary was limed by helicopter in 2013. Stream flow, water chemistry, and density of young-of-year (YOY) brook trout were measured in limed streams, an untreated acidified stream, and a buffered reference stream. Lime additions increased pH and acid-neutralizing capacity and decreased inorganic monomeric aluminum concentrations to less than 2.0 μmol/L, the minimum concentration at which in situ brook trout mortality has been documented. However, of the two channel-limed streams, only stream T8 showed a significant response (P < 0.01) in YOY density, increasing from a mean of 0.4 fish/m2 before liming to 2.7 fish/m2 after liming. No YOY brook trout response was observed in the stream within the limed watershed. Groundwater inputs to streams were identified by relative differences in temperature and concentrations of silica and sodium. YOY brook trout densities increased only in the channel-limed stream (T8) with suitable groundwater inputs for fall spawning and a summer nursery. Results suggest that targeted liming of acidified streams with the necessary groundwater habitat could be beneficial in accelerating recovery of brook trout populations.

Epidemiological Significance of Crown Rot in the Fruiting Field in Relation to Colletotrichum gloeosporioides Infection of Strawberry Nursery Plants.

Anthracnose crown rot (ACR), caused by Colletotrichum gloeosporioides, is a serious disease of strawberry (Fragaria × ananassa) in the southeastern United States, and there is a need to determine the link between nursery and fruiting-field disease risk. A 2-year study in 2007, repeated in 2008, was conducted at the North Carolina State University Horticultural Crops Research Station, Clinton, using 'Chandler', the most popular cultivar in North Carolina and one that is highly susceptible to ACR. Mother plants in a summer nursery were inoculated midseason with three pathogenic strains of C. gloeosporioides at an incidence level of 0, 5, 10, or 25%. Asymptomatic runner plants were selected at maturity (85 to 88 days after inoculation) from the nursery in early to mid-October from within a 0.5-m (inner) or 0.5- to 1.0-m (outer) radius around inoculated mother plants and planted into a plasticulture fruiting field system, with fruit harvest in April to June the following spring. Plants collected from the 25%-inner treatment had the greatest area under the disease progress curve (AUDPC) values, with a terminal ACR-related plant mortality of 32 and 20% by the end of fruit harvest and marketable yield losses of 30.5 and 30.2% in 2007-08 (Yr1) and 2008-09 (Yr2) seasons, respectively. All treatments increased AUDPC values compared with noninoculated treatments except the 10%-outer (O) and 5%-O treatments in Yr1 and Yr2, respectively. Marketable yield decreased 291.6 kg/ha for every percent increase in inoculum level (i.e., 0 to 25%, R2 = 0.696, P = 0.001). Levels of quiescent infection (QI) incidence (percentage of sampled leaves) assessed 25 to 28 days before digging runner plants also directly affected yield. For example, yield decreased 131.0 kg/ha for every percent increase in QI incidence in mother plants (R2 = 0.744, P = 0.001). Immersion of plants in fungicide solutions prior to planting decreased AUDPC values and improved plant stand by 7 to 11% but did not affect marketable yield compared with controls. This study provides results that can enable nursery and fruit growers to assess risk and implement mitigation measures to limit nursery plant and fruit yield losses.

Can expired proprietary maize (Zea mays L.) industry lines be useful for short-season breeding programs? II. Agronomic traits

U.S. Patent and Plant Variety Protection Act protect maize (Zea mays L.) inbreds and hybrids. The overall objective of this research was to assess the usefulness of patent expired maize inbred lines. Factorial crosses were made including North Dakota State University (NDSU) lines, ex-PVP lines, and top industry testers in the 2010 NDSU Fargo summer nursery and in the 2010–2011 NDSU New Zealand winter nursery. Hybrids were planted across six different ND environments in 2011 and 2012 following partially balanced lattice experimental designs. Combining ability analyses were performed following a factorial design with fixed parents. Our research identified ex-PVP inbreds PH207, Q381, PHP02, S8324, PHK76, CR1Ht, PHT77, LH205, LH54, and PHJ40 as above average lines in hybrid combinations to increase yield. Our trials suggest most ex-PVP lines are not useful directly for commercial purposes but could be used as potential breeding sources for short-season maize breeding programs. Improvements in intellectual property and re-thinking of breeding rights access are encouraged to explore more suitable hybrids for northern U.S. farms. Current industry lines have important trait weaknesses for northern U.S. climates that public sector breeders in strategic breeding locations could improve in order to develop better hybrids for farmers. Our preferred choice would be to partner with industry in order to improve current industry lines with known weaknesses, especially for northern U.S. and Canada environments.

English

The response of ‘Ventana’, an early flowering cultivar, and ‘Camarosa’, an intermediate flowering cultivar, to nursery late-season nitrogen (N) applications and digging date were studied in strawberry (Fragaria x ananassa Duch). Two experiments were conducted. In the first experiment, runner plants dug on September 20 and October 11 from a high-latitude nursery in California, were established in growth chambers set at 25°/15oC day/night temperature, 12-h photoperiod, and grown for 90 days. Compared to the first experiment, in the second experiment plants received extra N (foliar-applied) in the nursery in late summer, and runner plants were not grown in GC but in open field (Irvine, California). In the second experiment, runner plants were dug on Sept 20 and Oct 2. In both experiments, plants dug in September were exposed to ~100 chilling units (CU: hours ≤7.2°C) and plants dug in October were exposed to ~300 CU. As a result, October-dug plants had greater crown and root dry weight, and greater concentration of starch and total nonstructural carbohydrates (TNC) in leaves, crowns and roots, compared to September-dug plants. In control plants, from September to October, root TNC concentration increased in ‘Camarosa’ from ~6% to ~11%, and in ‘Ventana’ from ~14% to ~21%, and leaf N concentration ranged from 1.47 to 1.81% in ‘Camarosa’, and from 1.60 to 1.96% in ‘Ventana’. Late-summer N applications increased plant N concentration and early-season yields. Late-summer nursery N applications reduced dead leaf biomass (DLB) and dead leaf area (DLA) in both cultivars, although ‘Ventana’ had lower DLB and DLA than ‘Camarosa’. ‘Ventana’ had a greater leaf number and flowered earlier, and had greater early fruit production than ‘Camarosa’. The genetic earliness of ‘Ventana’ would be correlated with the potential of the plant for accumulation of higher initial levels of leaf N and root TNC, and for having greater leaf longevity, compared to ‘Camarosa’. Key words: Fragaria x ananassa Duch., foliar urea, carbohydrates, chilling, plant maturity, early flowering cultivars.

イチゴうどんこ病の苗での越夏

イチゴうどんこ病の苗での越夏

English

&nbsp; The influence of late-season nitrogen (N) applications on the fruiting pattern of strawberry runner plants of &lsquo;Camarosa&rsquo; was determined over three growing seasons. Experiments were carried out in high-latitude nurseries in northern California and fruit production trials were established in southern California. A total of 80 kg/ha of foliar nitrogen was delivered in three applications to the nursery in late summer. Late-season foliar nitrogen applications: (1) increased early yields (+22% on average) as well as the number of early marketable fruit, (2) did not affect total season yields, fruit size, appearance and firmness and (3) resulted in greater N concentration in leaves, crowns and roots. Runner plants with leaf N concentration within the sufficiency range (1.9 - 2.8% of dry mass) produced the highest early yields. Total nonstructural carbohydrate concentrations decreased in most of the N-treated plants. Apparently, nursery late-season foliar nitrogen applications enhance N mobilization to crown and root, stimulate plant activity during the period of flower differentiation after planting, accelerating flower development and contributing to the advancement of fruit production. &nbsp; Key words:&nbsp;Fragaria&nbsp;x&nbsp;ananassa&nbsp;Duch, foliar urea, carbohydrates, high-latitude nursery, plant maturity.

Residency, space use and movement patterns of juvenile sandbar sharks (Carcharhinus plumbeus) within a Virginia summer nursery area

Neonates and juveniles of many large coastal shark species occupy shallow inshore nursery areas during portions of the year. The identification of how these areas are used by large coastal shark populations is an important consideration in conservation and management efforts. An array of passive acoustic receivers was utilised to track the movements of 64 neonate and juvenile sandbar sharks within the Eastern Shore of Virginia summer nursery during the summers of 2003–2005. Residency patterns were variable during each year of the study, with younger sandbar sharks spending more time within the array area than older sharks. The number of detections was positively related to the distance of the receiver inshore from the inlet, indicating that young sandbar sharks preferentially utilise protected, shallow near-shore waters. Neonate and juvenile sandbar sharks tended to be detected more frequently within all areas of the inlet at slack tides, during the night and during early dawn hours. Periodogram analyses indicated that juvenile sharks tend to move in the direction of tidal currents. The present study documents large- and small-scale movement patterns of juvenile sandbar sharks and emphasises the importance of nursery-area habitats for this species.

Divergent recurrent selection for cold tolerance in two improved maize populations

Maize (Zea mays L.) production has significantly expanded into very short-season environments where germination and growth in cooler environments is essentially a pre-requisite. Therefore, an important goal for maize breeders is to improve local germplasm sources of inbred lines that are able to grow under these challenging conditions. The objective of this research was to evaluate direct and correlated responses in two improved early maturing maize populations [NDSCD(M)C10 and BS22(R)C7] after two cycles of S1 and full-sib intra-population recurrent selection for cold tolerance. The S1 and full-sib progenies were obtained by self-pollinating 100 random plants and by intercrossing 200 random plants, respectively. Ten percent of the families were selected, based on an index that included emergence percentage, seedling vigor, and root lodging percentage, and recombined at the same time in a summer nursery based upon data across northern North Dakota locations. The essential benefit of this breeding methodology was to achieve one year per cycle of selection based upon progenies. However, direct response to selection was not significant while some correlated responses were significant. We decided to report these results in order to encourage other scientists the evaluation of additional sources of germplasm, the screening at various dates, and the selection of target environments with more intensive cold stress before initiating long-term selection programs for cold tolerance. In addition, further research on the current and alternative long-term selection methods for cold tolerance is recommended for continuous genetic improvement of advanced cycles in the northern U.S. Corn Belt.

The Sandbar Shark Summer Nursery within Bays and Lagoons of the Eastern Shore of Virginia

AbstractWe sought to examine the spatial use of coastal bays and lagoons associated with the Eastern Shore of Virginia (i.e., the Atlantic shoreline north of the mouth of the Chesapeake Bay) as nursery habitat for sandbar sharks Carcharhinus plumbeus. Generalized linear mixed models were used to examine the relationship between physical factors and the abundance of neonate and juvenile sandbar sharks within the study area. Neonates, small juveniles, and large juveniles were present throughout the sampling area in relatively high abundance throughout the months of June‐September. Abundances of neonates and small juveniles were correlated with sampling distance from the inlet; larger fractions of these groups were captured as distance from the inlet increased. Large‐juvenile abundance was not significantly correlated with any physical factor. The catch rates of neonate and juvenile sandbar sharks within this area were comparable with those observed in nearby Chesapeake Bay, although a larger number of juveniles greater than 100 cm total length were caught within the Eastern Shore lagoons. The bays and lagoons we examined function as an important primary and secondary nursery ground for this species and fit the criteria to be included in future management measures as a habitat area of particular concern.

Autumn swarming behaviour of Natterer’s bats in the UK: Population size, catchment area and dispersal

Many species of temperate bats visit underground sites in autumn, prior to hibernation, and chase each other in and around the entrances in an event known as autumn swarming. It has been suggested that swarming is a mating event that facilitates gene flow between bats from otherwise isolated summer colonies. We describe swarming behaviour at a cluster of four caves in the North of England and provide direct evidence for seasonal migration of Natterer’s bats ( Myotis nattereri ) between these caves and many summer nursery roosts in a catchment area of at least 60 km radius. Mark-recapture analysis suggests that an estimated 2000–6000 Natterer’s bats use the three best-studied caves, together with smaller numbers of four other species: M. daubentonii, M. brandtii, M. mystacinus and Plecotus auritus. Recaptures also show that there is a small interchange of bats between these three caves, which are 0.6–1.5 km apart. Capture rates, automatic logging and video recordings at one cave suggest that an average 310–400 bats visit the cave each night. Mating at swarming sites would be particularly important for gene flow if a species showed no other dispersal pattern. We provide evidence for natal philopatry, with little or no dispersal, in both sexes of Natterer’s bats. The protection of swarming sites is discussed in light of our findings.

Quantitative analysis of aggregation behavior in juvenile blacktip sharks

Aggregation patterns of a population of juvenile blacktip sharks (Carcharhinus limbatus) within a summer nursery area were examined over a period of 3 years using an array of acoustic monitors. Individually coded acoustic tags were surgically implanted into 33–40 neonate sharks each year from 2000 to 2002 and their presence monitored continuously by the acoustic array. Data from the acoustic monitors was processed to estimate the center of activity location of each tagged shark every 30 min. Nearest neighbor analysis of shark locations revealed that sharks aggregated within the nursery in all years of the study. Sharks were aggregated most commonly during the early and late summer months (June, October and November) and became less common through the middle of the study period each year (July–September). Temporal periodicity within the data revealed a strong diel pattern with sharks aggregating during the day and dispersing at night, except in June when aggregations often persisted through the night. Aggregations were generally restricted to the mid and northern sections of the study site. Reasons for aggregations may include predator avoidance or improved feeding efficiency.

BA-Induced Shoot Formation in Indian Hawthorn

Abstract A study was conducted to determine effects of multiple weekly applications of different concentrations of a synthetic cytokinin, benzyladenine (BA), on two Indian hawthorn [Rhaphiolepis Lindl. Cor. Poir. indica (L.) Lindl. (Crataegus indica L.)] cultivars, ‘Olivia’ and ‘Eleanor Taber’. In a greenhouse in winter 2000-2001, ‘Olivia’ Indian hawthorn received four weekly applications of 2500 ppm or 5000 ppm BA. At 45 days after last treatment (DALT) untreated plants had formed no new shoots, while plants treated with 2500 and 5000 ppm BA produced 6.8 and 5.4 new shoots, respectively. New leaves of plants treated with 5000 ppm BA were abnormally mottled, twisted, and cupped. In an outdoor nursery in summer 2001, ‘Olivia’ in 3.8 liter (#1) and 26.5 liter (#7) containers received three and two applications, respectively, at concentrations from 0 to 5000 ppm. Untreated plants in 26.5 liter (#7) containers formed 4.7 new shoots at 30 days after initial treatment (DAIT), and new shoots increased from 83 with 1250 ppm BA to 126 with 5000 ppm BA. Plants in 26.5 liter (#7) containers were retreated in September, at which time shoots were inactive. At 30 DAIT controls averaged less than one new shoot per plant, while plants averaged 18 new shoots when treated with 1250 ppm BA and 105 new shoots when treated with 5000 ppm BA. In spring 2002, plants in 3.8 liter (#1) containers were retreated following the same protocol as in 2001, in conjunction with a new set of ‘Olivia’ and the Indian hawthorn cultivar, ‘Eleanor Taber’. At 30 DALT new shoot formation increased three fold in ‘Olivia’ and five fold in ‘Eleanor Taber’ after three applications of up to 5000 ppm BA. Injury increased with increasing BA rates in ‘Olivia’ at 30 DALT, with leaf cupping and discoloration apparent on plants treated with concentrations above 1250 ppm. No injury was observed in ‘Eleanor Taber’. By 90 DALT new shoots had matured normally and exhibited minimal phytotoxic symptoms.

The demersal fish assemblage of the coastal area adjacent to the Tagus estuary (Portugal): relationships with environmental conditions

The subtidal fish assemblage of Tagus estuary coastal area was sampled in order to infer about its relationship to environmental conditions and its possible nursery function for marine species. Fish sampling took place between May 2001 and February 2002 with an otter trawl. In addition to fish sampling, a physical, chemical and biological characterization of the water column and bottom sediment was performed. Density and biomass were determined and ecological and feeding guilds assigned to each fish species. Correspondence analysis (CA) was used to determine the spatio-temporal structure of the assemblage and its correlation to environmental variables. A total of 36 fish species were identified. The fish assemblage was dominated by few species, both in terms of density and biomass. The main fish species were Callionymus lyra, Arnoglossus laterna, Diplodus bellotti, Echiichthys vipera and Raja undulata. Seasonally Trachurus trachurus, Sardina pilchardus and Engraulis encrasicolus were also abundant. Over 50% of the fish caught were juvenile stages. Benthic carnivorous species feeding on invertebrates dominated the assemblage. CA results indicated that distinct fish species occur in the northern and southern areas, although they distance only a few kilometres from each other. Depth and sediment type were the main structuring factors of the fish assemblage. Temperature and salinity showed reduced importance on overall assemblage structure although that may result from the particular climatic regime of the sampling year. The environmental preferences of the most important species are briefly discussed and the importance of integrating various spatial scales in multispecific studies of coastal fish assemblages emphasized. The presence of high densities of marine species juveniles indicates that this area may function as a spring–summer nursery for several species.

Distribution of the Mediterranean hake populations (&lt;i&gt;Merluccius merluccius smiridus&lt;/i&gt; Rafinesque, 1810) (Ostheichthyes: Gadiformes) based on six years monitoring by trawl-surveys: some implications for management

On the basis of trawl survey data collected during the MEDITS project (1994-1999), the distribution of Mediterranean hake populations was described in coastal areas corresponding to about three quarters of both the latitudinal and longitudinal extensions of the Mediterranean Sea, and in the 0-800 m range. Abundance and biomass indices (in terms of number and kg per km2) are presented in 15 geographical sectors and 40 subareas from the Alborán Sea to the Aegean Sea. A statistical analysis by generalized linear modelling performed on such indices per main national blocks (Greece, France, Italy and Spain), and considering the effects of the six years of sampling and the depth, showed that biomass increased from west to east, while for all areas the most significant depth effect appeared between 100 and 200 m, corresponding to the depth range that hosts most of the summer nursery areas. The overall size-frequency distributions in shelf and slope waters, average sizes and total mortality coefficient Z per sector showed that the bulk of the MEDITS samples consisted of young individuals and, with only a few exceptions (western Sardinia, central Aegean), a generalized condition of growth overfishing was apparent. However, no negative trend was found, either in biomass or in average size of fishes, during the six years of the present study. Recruitment patterns were studied by distinguishing the youngest fish as Gaussian groups (modal length from 6 to 9 cm total length) in length-frequency distributions of each subarea and main stratum (shelf and slope). Considering the timing of MEDITS surveys (May-July), this approach emphasised the nurseries in the northern part of the western Mediterranean (Gulf of Lions, Ligurian Sea, northern Tyrrhenian Sea) and in the northern central Mediterranean, where recruitment occurs mainly during spring. On the other hand, few recruits were found in part of the central and particularly in the eastern Mediterranean, where recruitment occurs mainly in summer. MEDITS recruitment patterns therefore gave support to distinctions among Mediterranean hake populations, previously suggested on the basis of vertebral counts and other morpho-physiological, albeit fragmentary, data. In particular the central Mediterranean hake populations do not seem to be homogeneous, with an Adriatic unit very close to the northwestern one. The MEDITS experience therefore suggests that future management measures could take into account both general and regional patterns, the latter concerning mainly the younger fraction of the populations.

Distribution, Movements and Growth of Young Sandbar Sharks, Carcharhinus Plumbeus, in the Nursery Grounds of Delaware Bay

During the spring and summer months of 1995, 1996 and 1997, gillnet and longline surveys were conducted in conjunction with tag and recapture experiments to outline spatial and seasonal distribution of young sandbar sharks, Carcharhinus plumbeus, in Delaware Bay for essential fish habitat mapping, to assess abundance of young sandbar sharks, and to quantify growth during the summer nursery season. Sandbar sharks (n = 943) ranging from 40 to 120 cm fork length (48 to 130 cm total length) were captured; yearly totals were 199, 314 and 430 in 1995, 1996 and 1997, respectively. Individuals were captured between June and October in water temperatures ranging from 15.4° to 28.5°C and salinities ranging from 22.8 to 30.3 ppt. Presence of neonates and catch per unit effort data indicate that pupping begins in late June near the southwestern coast of the Bay. Juveniles were present from early June through September and their spatial distribution in the Bay appeared uniform. Of 782 sandbar sharks tagged and released during the three years, 50 were recaptured. Mean distance from tag to recapture location and mean days-at-liberty of sandbar sharks recaptured in Delaware Bay during the year of tagging were 10 km and 18 days, respectively. Some sharks were recaptured as far as 957 km from the release location. Length distributions show young-of-the-year sandbar sharks grow about 2–3 cm in length during the nursery season.

Abnormal STEM Development in Maize nal/nal Mutant - A Confocal Microscopy Study

Abstract There are number of dwarf mutants in maize such as d8, dl and nal. The nana plant 1 (nal/nal) is characterized as short erect dwarf; the phenotype does not respond to treatment of giberellins. The recessive nal allele is located on the long arm of chromosome 3 (3L-113). In this study, we report the abnormal development of the stem vasculature and the lack of clearly defined nodes. Maize (Zea mays L., var. Ohio 43 and nal mutant) plants were grown in 1999 summer nursery at the fieldstation of University of Western Ontario, London Ontario, Canada. Plants at approximately 2 months old were fixed in 1:3 acetic acid/ EtOH. Multiple changes of fixative were made for a period of a month to remove as much pigmentation as possible. The specimen was then washed thoroughly, stained in diluted Schiffs reagent (10%), washed in 0.1M metabisulphate solution (with 1 ml of 1 N HC1 per liter), dehydrated in EtOH and cleared in methyl salicylate.

GENETIC BASIS AND EVOLUTIONARY SIGNIFICANCE OF VENTRAL SKIN COLOR MARKINGS IN NORTH ATLANTIC RIGHT WHALES (EUBALAENA GLACIALIS)

AbstractApproximately one third of the North Atlantic right whale population has white ventral skin patches. Most white‐marked animals have both a belly and a chin patch, and the distribution of white pigment suggests that the patches represent a single ventral marking that varies in size and location. Population frequencies and cow‐calf inheritance patterns indicate that the white mark is an autosomal recessive trait. There is no evidence to suggest that ventral coloration patterns are currently under selection. White‐marked and black cows appear to experience similar levels of reproductive success based on calving intervals and length of sighting histories. Also, white‐marked animals were equally common among cows and nulliparous adult females and among live vs. dead animals. Male reproductive success could not be tested because calf paternity is not known; white‐marked and black males exhibit similar survival rates. White‐marked cows were more common among females that took some or all of their calves to the Bay of Fundy summer nursery area compared to females that did not visit Fundy. This suggests that female habitat‐use patterns may influence nuclear gene flow. Increased sample sizes and additional markers are needed to further investigate gene flow.

Assessment of the population structure of western North Atlantic right whales (Eubalaena glacialis) based on sighting and mtDNA data

Photoidentifications and 11 years of sighting data revealed that only two-thirds of the western North Atlantic right whale (Eubalaena glacialis) reproductive females took their calves to the Bay of Fundy, the only known summer nursery. Study of cow–calf pairs further indicated that female, and to a lesser extent male, calves were philopatric with respect to this nursery. To further examine population structure, mtDNA composite restriction morphs were determined for 150 animals (47% of the population). Using 11 restriction enzymes, three composite mtDNA morphs were identified. One morph was not found among reproductive females that brought all of their calves to the Bay of Fundy. In contrast, all three morphs were present, in the same relative frequencies, among males that were seen in the Bay of Fundy and those that were not. These findings support the hypothesis that this population may be divided into two subgroups, which are defined by their use of the Fundy nursery, and that males are generally less philopatric than females. Animals from both subgroups were seen on the southern Scotian shelf, where most right whale courtship behavior was observed. Hence, although segregated by nursery areas, the western North Atlantic right whales probably represent a single breeding population.