DNA microsatellite analysis of sporophytes of the short-lived moss Physcomitrium pyriforme reveals a predominantly self-fertilizing mating pattern
Robert A. Klips. 2015. The Bryologist 118(2):200-211. doi: http://dx.doi.org/10.1639/0007-2745-118.2.200
Physcomitrium pyriforme (Funariaceae) is a monoicous moss with the potential for producing sporophytes either via outcrossing or intra-gametophytic self-fertilization. A core set of microsatellite markers was identified for use in population genetic studies of this species, and employed to ascertain its mating patterns. An initial collection of 88 sporophytes gathered from widely separated locations in a meadow in central Ohio, U.S.A. was screened for genetic uniformity based on trnL-F DNA sequences, and found to display considerable heterogeneity. Fifty-three members of the largest clearly defined clade were selected for genotyping at 6 variable microsatellite loci having expected heterozygosities ranging from 0.11 to 0.70. Fifty-two individuals (98.2%) were homozygous at all 6 loci, strongly indicative of self-fertilization. Only one individual (1.8%) appeared to be an outcrossed sporophyte, being heterozygous at 4 loci. Twenty-three samples that constituted a second well-marked clade displayed complex microsatellite genotypes strongly suggestive of a polyploid cytotype that, although not readily amenable to further analysis, is also not inconsistent with the predominantly selfing mating pattern exhibited by the 53 others. Male and female branches within gametophyte stems were observed to develop simultaneously or nearly so, and in 4 dense moss clusters within which samples of 8 gametophytes were genotyped, all 8 were found to be identical within each cluster. These results indicate that the overall mating pattern is predominantly selfing, and suggest that the species reproduces principally in what is, in effect, a clonal fashion, via the union of genetically identical gametes. This may be occurring both within and between gametophytes.
Post-embryonic development in the mite suborder Opilioacarida, with notes on segmental homology in Parasitiformes (Arachnida)
In order to study homology among the major lineages of the mite (super)order Parasitiformes, developmental patterns in Opilioacarida are documented, emphasizing morphology of the earliest, post-embryonic instars. Developmental patterns are summarized for all external body structures, based on examination of material in four different genera. Development includes an egg, a 6-legged prelarva and larva, three 8-legged nymphal instars, and the adults, for the most complete ontogenetic sequence in Parasitiformes. The prelarva and larva appear to be non-feeding. Examination of cuticular structures over ontogeny allows development of an updated model for body segmentation and sensillar distribution patterns in Opilioacarida. This model includes a body made up of a well-developed ocular segment plus at most 17 additional segments. In the larvae and protonymphs each segment may carry up to six pairs of sensilla (setae or lyrifissures) arranged is distinct series (J, Z, S, Sv, Zv, Jv). The post-protonymphal instars add two more series (R and Rv) but no extra segments. This basic model is compatible with sensillar patterns in other Parasitiformes, leading to the hypothesis that all taxa in that (super)order may have the same segmental ground plan. The substantial segmental distortion implied in the model can be explained using a single process involving differential growth in the coxal regions of all appendage-bearing segments.
Research Summary: Dreissenid Mussel Impacts On Plankton Dynamics In Western Lake Erie
Long Jiang, Meng Xia, Stuart A. Ludsin, Edward S. Rutherford, Doran M. Mason, Jose R. Marin Jarrin, Kevin L. Pangle. 2015. Lake Scientist.
The ability to describe the distribution and dynamics of plankton communities can benefit both our understanding and management of aquatic ecosystems. For example, indices of plankton community composition and dynamics have been used to track environmental changes in both freshwater and marine ecosystems, as well as assess ecosystem health (e.g., Allinger and Reavie, 2013; Lugoli et al., 2012). Likewise, because higher consumers such as fish depend on plankton as prey during one or more life stages, long-term fisheries dynamics have been linked to shifts in the plankton community (e.g., Beaugrand et al., 2003).
Aquatic Ecology Lab
Reproductive sharing in relation to group and colony-level attributes in a cooperative breeding fish
Motivation but not body size influences territorial contest dynamics in a wild cichlid fish
We studied contests in wild free-living Neolamprologus pulcher, a cooperatively breeding fish. Males were briefly removed from territories, and then engaged in contests with usurping males. The relative size difference between the males had no effect on contest dynamics or outcome. Perceived resource value influenced male aggression. More aggressive fish were more likely to win contests.
Ten+ years gone: Continued degradation of offshore planktonic communities in U.S. waters of Lake Erie's western and central basins (2003–2013)
Mounting evidence exists to indicate that Lake Erie is once again experiencing eutrophication. Such signs include increases in both the incidence of harmful algal blooms in the western basin and the re-emergence of large hypoxic areas in bottom waters of the central basin. Towards further assessing Lake Erie's health and the degree to which this ecosystem has become more eutrophic, we calculated a Planktonic Index of Biotic Integrity (P-IBI) for the western and central basins of Lake Erie during 2003–2013 and compared values to P-IBI values from previous periods of heightened eutrophy (1970) and the recovery from eutrophy (1995–2002). As expected, P-IBI scores in the eutrophic/hypereutrophic range (< 3) have predominated in both the western and central basins during 2003–2013. This decline in P-IBI scores (and hence, ecosystem health), however, has been more evident in the western basin than in the central basin.
Continuous activity and no cycling of clock genes in the Antarctic midge during the polar summer
The extreme seasonal shifts of day length in polar regions, ranging from constant light in the summer to constant darkness in the winter, pose an intriguing environment for probing activity rhythms and the functioning of circadian clocks. Here, we monitor locomotor activity during the summer on the Antarctic Peninsula and under laboratory conditions, as well as the accompanying patterns of clock gene expression in the Antarctic midge, the only insect endemic to Antarctica. Larvae and adults are most active during the warmest portion of the day, but at a constant temperature they remain continuously active regardless of the photoregime, and activity also persists in constant darkness. The canonical clock genes period, timeless, Clock, and vrille are expressed in the head but we detected no cycling of expression in either the field or under diverse photoregimes in the laboratory. The timekeeping function of the clock has possibly been lost, enabling the midge to opportunistically exploit the unpredictable availability of permissive thermal conditions for growth, development, and reproduction during the short summer in Antarctica.