Small whorled pogonia, Isotria medeoloides, is a rare terrestrial orchid of temperate forests in eastern North America. It is federally threatened, and 1992 recovery criteria in place for this species need to be evaluated in light of current data. Study of I. medeoloides demography is complicated by the potential for belowground dormancy lasting one to three or more years. From 1986 to 2000, we observed 404 individuals in monitoring plots at four sites in Maine, USA, with up to 241 additional plants followed less intensively outside those plots. We used a life cycle diagram to summarize stage distribution data regarding emergence, recruitment, fruiting, and dormancy. A frequency analysis of the stage dynamics of individuals revealed no consistent patterns. Within plots, 17.9% of individuals bore fruits. Of plants that flowered, mean fruit set overall was 55%. Plant abundance within plots declined over time, possibly due to increasing shade and weather-related effects. In 1993, we removed 33% of the tree basal area over subsections of the populations at two sites while also leaving a portion of both sites untreated. We used mixed-effect regressions to test for increased recruitment and rate of capsule production as a result of the canopy treatment. As of 1993, for 187 plants in the treated zones mean capsule production per flowering plant did not decline, while it did decline in the untreated zones. In a subset of 100 paired plants matched by year and site, 95.8% of those impacted by severe herbivory were dead within 4 years, compared to 58% of counterparts with no herbivory. We used these data to evaluate the recovery criteria and recommend a change from a focus on percent flowering to a minimum of at least two capsules produced per year on average over a ten-year period.

The timing and spatial variation in spawning in the green sea urchin Strongylocentrotus droebachiensis (Muller) was investigated at three moderately protected sites in each of three geographic regions along the coast of Maine before the commencement of significant commercial harvesting. Urchins were sampled monthly (1987 to 1988) from subtidal hard bottoms, and test diameter (TD), height, total wet weight, and gonad wet weight were measured. To interpret reproductive and spawning patterns additional data were taken on habitat type, water temperature, salinity, urchin density, and diets. Over a range of TD (34.1-89.4 mm), 1,594 urchins were sampled. Gonad index (GI) increased as an allometric function of TD, and for urchins from the northeast and southwest regions, GI was independent of TD for animals >= 64 mm. In the central region, the size at independence was >= 55 mm. Analysis of variance with a priori, planned contrasts was used to quantify temporal changes in GI and spawning at two spatial scales (within and between regions). This information serves as a preharvest baseline for green urchin dynamics, analysis of reproductive cycles and spawning, and for current and future ocean changes. Gonad index and spawning varied seasonally, spatially and interannually. Gonad index increased during fall and early winter, and peaked in midwinter before a major spawning event in April at seven of nine sites. Gonad index ranged from 10% to 20% from December to April. Spawning [measured as a steep decline in GI (48%-78%) between successive sampling dates) occurred between early April and mid-May, except at one site in the central (Lamoine: March to April) and one in the northeast (Jonesport: May to June) regions. Gonad index patterns during spawning corresponded inversely to increasing seawater temperatures in the range of 2.5-5 degrees C. Salinity, urchin density, and test size did not explain a significant proportion of the variability in mean GI through time. Diets consisted primarily of diatoms and microalgae on ledge, sediment, and coralline barrens and showed no regional trends. Sex ratio explained a significant portion of the variability in mean GI at only one site. Seawater temperature, however, explained 55%-77% of the variability in mean GI through time. Predicting when spawning occurs in natural populations is central to the sea urchin fishery by refining estimates of what are termed harvest windows (HW). The HW represents a segment of time during the general spawning season when GI are at, or above, a specified percent, for example, 10%. A review of the literature uncovered 19 different techniques to determine GI and assess spawning. Of 167 papers published between 1922 and 2013 in which methods of spawning in wild populations of sea urchins were described, 84 and 134 used histology and GI, respectively. This study contributes to the questions of dependence of GI on test size, first illuminated by Gonor (1972), and the general practice of interpreting minor declines in GI as fractional spawning events, rather than simply sampling noise. The use of statistical tests is encouraged to define aspects of the reproductive cycle in sea urchins.

Agamospermy, which is almost always associated with polyploidy, is often assumed to reduce variation and foster evolution of microspecies. We tested for the occurrence of microspecies by comparing variation of sexual Amelanchier bartramiana and facultatively agamospermous (asexually seed-producing) Amelanchier laevis. We assessed within-and among-population variation of 222 individuals from six Maine populations of each species for eight morphological variables. Mahalanobis distances between individuals and population centroids and between population centroids and species centroids were used as measures of within-and among-population variation, respectively. Amelanchier bartramiana contains significantly more within-and among-population morphological variation than A. laevis. The two species do not differ in how they partition morphological variation within and among populations. Amelanchier laevis thus does not contain microspecies. Variation within A. laevis may be the result of sexuality, hybridization, polyploidy. and other factors.

We compared genetic variation of sexual Amelanchier bartramiana and facultatively agamospermous (asexually seed-producing) A. laevis at one site where the two species are sympatric. We analyzed 77 random amplified polymorphic DNA (RAPD) markers in 29 A. bartramiana individuals and 76 RAPD markers in 31 A. laevis individuals. The two species do not differ significantly in mean genetic variation. However, 22.4% of genetic similarity values between A. laevis individuals exceed the highest value of A. bartramiana and may represent the effect of agamospermy. Variation within A. laevis may be the result of sexuality, hybridization, polyploidy, and other factors.

Apomixis and hybridization together contribute to taxonomic complexity inAmelanchier. Hybridization combines genetically divergent genomes and spawns new forms that apomixis perpetuates. Apomixis is aposporous, facultative, and pseudogamous in the genus, and apomicts are generally polyploid, pollen fertile, and pollinated by generalists. That gene flow actually occurs is empirically evident. As apomixis is genetically dominant over sexuality, hybrids involving at least one apomictic parent are apomictic. Clonal reproduction may thus perpetuate F1 individuals and generate agamospecies. Alternatively hybrids may interbreed and backcross to create hybrid swarms or cross with species other than the parents. In eastern North America, the abundance of published names and general taxonomic confusion in the genus doubtless result at least in part from this interplay of apomixis and hybridization. The roles of apomixis and hybridization in diversification withinAmelanchier are examined in light of new data about breeding system of an apomictic, hybrid microspecies, informally namedA. “erecta” and its formation of a hybrid swarm with anotherAmelanchier apomict,A. laevis.