Computer vision in aquaculture: a case study of juvenile fish counting.

In aquaculture breeding or production programmes, counting juvenile fish represents a considerable cost in terms of the human hours needed. In this study, we explored the use of two state-of-the-art machine learning architectures (Single Shot Detection, hereafter SSD and Faster Regions with convolutional neural networks, hereafter Faster R-CNN) to augment a manual image-based juvenile fish counting method for the Australasian snapper () bred at The New Zealand Institute for Plant and Food Research Limited. We tested model accuracy after tuning for confidence thresholds and non-maximal suppression overlap parameters, and implementing a bias correction using a Poisson regression model.

Historical human activities reshape evolutionary trajectories across both native and introduced ranges.

The same vectors that introduce species to new ranges could move them among native populations, but how human-mediated dispersal impacts native ranges has been difficult to address because human-mediated dispersal and natural dispersal can simultaneously shape patterns of gene flow. Here, we disentangle human-mediated dispersal from natural dispersal by exploiting a system where the primary vector was once extensive but has since ceased. From 10th to 19th Centuries, ships in the North Atlantic exchanged sediments dredged from the intertidal for ballast, which ended when seawater ballast tanks were adopted.

Hybridization is associated with changes in sexual system in the bryophyte genus Atrichum.

Premise Of The Study: Over 50% of bryophytes have separate sexes, and numerous transitions have occurred between combined and separate sexes. Polyploidy and hybridization is one proximate mechanism hypothesized to cause evolutionary transitions to hermaphroditism in bryophytes because sex is expressed at the haploid stage and in nonpolyploid dioecious species males have a single V chromosome and females a U. Hermaphroditism can arise if gametophytes of allopolyploids have both U and V chromosomes.

Polyploidy influences sexual system and mating patterns in the moss Atrichum undulatum sensu lato.

Background And Aims: Evolutionary transitions between separate and combined sexes have frequently occurred across various plant lineages. In mosses, which are haploid-dominant, evolutionary transitions from separate to combined sexes are often associated with genome doubling. Polyploidy and hermaphroditism have strong effects on the inbreeding depression of a population, and are subsequently predicted to affect the mating system.

Reproductive investment within inflorescences of Stylidium armeria varies with the strength of early resource commitment.

Background And Aims: Resource allocation to flowers, fruits and seeds can vary greatly within an inflorescence. For example, distal fruits are often smaller and produce fewer and smaller fruits and seeds than more basal fruits. To assess the causes and functional significance of intra-inflorescence variation, pollen and resources were manipulated to test whether such patterns could be altered within racemes of Stylidum armeria, a perennial Australian herb.

Correlated evolution of sexual system and life-history traits in mosses.

In mosses, separate and combined sexes are evolutionarily labile, yet factors selecting for this variation are unknown. In this study, we investigate phylogenetic correlations between sexual system and five life-history traits (asexual reproduction, chromosome number, gametophore length, spore size, and seta length). We assigned states to species on a large-scale phylogeny of mosses and used maximum likelihood analyses to test for the correlations and investigate the sequence of trait acquisition.

A test of simultaneous resource and pollen limitation in Stylidium armeria.

This study tests the Haig-Westoby model, which predicts that seed output will be limited simultaneously by pollen and resources when plants optimally distribute their reproductive investment. The test was conducted over 2 yr using Stylidium armeria in a factorial design that fully crossed three pollination levels (small stigmatic loads, open pollination, and supplementation of natural loads) with three levels of resource availability (reduction through partial defoliation, unmanipulated resource conditions, and supplementation through nitrogen, phosphorus and potassium (NPK) addition). There was no evidence of pollen limitation from supplemental pollination; however, pollen reductions (to about half the normal mean stigmatic loads) sharply reduced seed output.

The biochemistry of Rubisco in Flaveria.

C(4) plants have been reported to have Rubiscos with higher maximum carboxylation rates (kcat(CO(2))) and Michaelis-Menten constants (K(m)) for CO(2) (K(c)) than the enzyme from C(3) species, but variation in other kinetic parameters between the two photosynthetic pathways has not been extensively examined. The CO(2)/O(2) specificity (S(C/O)), kcat(CO(2)), K(c), and the K(m) for O(2) (K(o)) and RuBP (K(m-RuBP)), were measured at 25 degrees C, in Rubisco purified from 16 species of Flaveria (Asteraceae). Our analysis included two C(3) species of Flaveria, four C(4) species, and ten C(3)-C(4) or C(4)-like species, in addition to other C(4) (Zea mays and Amaranthus edulis) and C(3) (Spinacea oleracea and Chenopodium album) plants.

Sporophytic inbreeding depression in mosses occurs in a species with separate sexes but not in a species with combined sexes.

Inbreeding depression is a critical factor countering the evolution of inbreeding and thus potentially shaping the evolution of plant sexual systems. Current theory predicts that inbreeding depression could have important evolutionary consequences, even in haploid-dominant organisms. To date, no data have been reported on inbreeding depression in moss species.

A theoretical investigation of the evolution and maintenance of mirror-image flowers.

Enantiostyly is the deflection of the female sex organ either to the left or to the right side of the floral axis, resulting in mirror-image flowers. Two types of enantiostyly occur: in monomorphic enantiostyly, individuals exhibit both flower forms, whereas in dimorphic enantiostyly, the forms occur on separate plants. Monomorphic enantiostyly is known from at least 10 families, whereas dimorphic enantiostyly is reported in only three.

The development of enantiostyly.

Enantiostyly, the deflection of the style either to the left (left-styled) or right (right-styled) side of the floral axis, has evolved in at least ten angiosperm families. Two types of enantiostyly occur: monomorphic enantiostyly, in which individuals exhibit both stylar orientations, and dimorphic enantiostyly, in which the two stylar orientations occur on separate plants. To evaluate architectural or developmental constraints on the evolution of both forms of enantiostyly, we examined inflorescence structure and floral development among unrelated enantiostylous species.

The genetics of mirror-image flowers.

Conspicuous asymmetries in forms that are polymorphic within a species can be genetically or environmentally determined. Here, we present a genetic analysis of the inheritance of dimorphic enantiostyly, a sexual polymorphism in which all flowers on a plant have styles that are consistently deflected either to the left or the right side of the floral axis. Using Heteranthera multiflora (Pontederiaceae), a short-lived herb, we conducted crosses within and between left- and right-styled plants and scored progeny ratios of the style morphs in F(1), F(2) and F(3) generations.

Solving the puzzle of mirror-image flowers.

Enantiostyly is a plant sexual polymorphism in which female sex organs are deflected to the left or right -- resulting in 'mirror-image' flowers -- but, although it occurs in at least a dozen unrelated families of flowering plants, its adaptive significance has been unclear. Here we show that a mendelian locus governs the inheritance of style orientation and that this curious form of sexual asymmetry functions to promote cross-pollination in bee-pollinated plants.

Enantiostyly in Wachendorfia (Haemodoraceae): the influence of reproductive systems on the maintenance of the polymorphism.

Enantiostyly is a form of directional asymmetry in plants in which the style is deflected away from the main axis of the flower, either to the left or right side. In Wachendorfia (Haemodoraceae), a small genus of insect-pollinated geophytes restricted to the Cape Province of South Africa, populations are usually polymorphic for asymmetry. Here we investigate dimorphic enantiostyly in the four species of Wachendorfia to determine whether variation in their reproductive systems influences the maintenance of this genetic polymorphism.