Egg clutch dehydration induces early hatching in red-eyed treefrogs, Agalychnis callidryas

Terrestrial eggs have evolved repeatedly in tropical anurans exposing embryos to the new threat of dehydration. Red-eyed treefrogs, Agalychnis callidryas, lay eggs on plants over water. Maternally provided water allows shaded eggs in humid sites to develop to hatching without rainfall, but unshaded eggs and those in less humid sites can die from dehydration. Hatching responses of amphibian eggs to dry conditions are known from two lineages with independent origins of terrestrial eggs. Here, we experimentally tested for dehydration-induced early hatching in another lineage (Agalychnis callidryas, Phyllomedusidae), representing a third independent origin of terrestrial eggs. We also investigated how dehydration affected egg and clutch structure, and egg mortality. We collected clutches from a pond in Gamboa, Panama, and randomly allocated them to wet or dry treatments at age 1 day. Embryos hatched earlier from dry clutches than from wet clutches, accelerating hatching by ∼11%. Clutch thickness and egg diameter were affected by dehydration, diverging between treatments over time. Meanwhile, mortality in dry clutches was six-fold higher than in control clutches. With this study, early hatching responses to escape mortality from egg dehydration are now known from three anuran lineages with independent origins of terrestrial eggs, suggesting they may be widespread. Further studies are needed to understand how terrestrial amphibian eggs can respond to, or will be affected by, rapid changes in climate over the next decades.Fil: Salica, María José. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET - Salta. San Salvador de Jujuy; ArgentinaFil: Vonesh, James R.. Virginia Commonwealth University; Estados UnidosFil: Warkentin, Karen M.. Smithsonian Tropical Research Institute; Panamá. Boston University; Estados Unido

Leaf pigments and wax as traits of heat tolerance in field pea

Non-Peer Reviewe

Early maturity strategies in chickpea: pyramiding key genetic traits

Non-Peer ReviewedChickpea (Cicer arietinum L.) is a highly indeterminate species which continues to grow and produce pods through fall, especially in cooler and wetter seasons. This exposes the crop to frost damage resulting in reduced yield and quality. We hypothesized that earliness could be induced through some strategic traits including double podding, reduced internode length and early flowering. The objective of this study was, therefore, to determine the individual and combined effects of these traits on earliness in chickpea. Four single crosses were made: two with the early flowering parent, and one each with the double podding and short internode length parents. Segregating populations of F2–F4 generations were evaluated along with their parents in greenhouse and field trials. Significant genetic variability was observed for days to maturity of lower pods and percent pod maturity at four months after planting. In general, each trait had some effect on earliness, though the magnitude differed, and combining them into a single genotype may help to achieve the desired earliness in chickpea. The F2 population from the multiple cross (gene pyramiding) showed a wide range in maturity. Several had nearly complete maturity of pods at four months after planting. These were more determinate types as judged by smaller increases in height between flowering and maturity stages and uniform maturity of pods

Stabilizing yield and quality: early maturing chickpea for the prairies

Non-Peer ReviewedProgress in chickpea breeding has been constrained by lack of good sources of early maturity in the short-season temperate environment of western Canada. We hypothesized that the length of the chickpea life-cycle could be reduced through introgression of strategic genetic traits including short internode, double podding and early flowering. The result showed that both the double podding and early flowering traits had significant beneficial effects by reducing the duration of crop maturity in chickpea in the short-season temperate environment of western Canada. Pyramiding double podding, early flowering and other strategic genetic traits should lead to the development of extra short duration chickpea varieties more suited for cultivation in the Prairies and similar environments

Early flowering, short internode length, and double podding as components of early maturity in chickpea

Non-Peer ReviewedLate maturity, resulting from the indeterminate nature of the crop, is a critical production constraint in chickpea (Kumar and Abbo, 2001). In western Canada, the chickpea crop is often killed by fall frost while seeds/pods are yet filling, which reduces both the quantity and quality of economic yield (grain). It was hypothesized that incorporating early flowering, short internode length and double podding traits may shorten the overall duration of growth in chickpea. Early flowering would advance onset of reproduction, while the latter two traits hasten the rate of pod formation and then progress towards maturity. Hence, a study was initiated to determine the effect of these key traits on time (days) to maturity in chickpea

How ovule and node positions affect seed development in field pea plants exposed to heat stress

Non-Peer Reviewe

Scaling of polymers in aligned rods

We study the behavior of self avoiding polymers in a background of vertically aligned rods that are either frozen into random positions or free to move horizontally. We find that in both cases the polymer chains are highly elongated, with vertical and horizontal size exponents that differ by a factor of 3. Though these results are different than previous predictions, our results are confirmed by detailed computer simulations.Comment: 4 pages, 4 figure

Effects of hatching timing on red-eyed treefrog tadpoles: relative vulnerability varies among predators but not with hatchling age-structure, growth varies with the presence of more vulnerable tadpoles [poster]

In Gamboa, Panama, undisturbed red-eyed treefrog embryos typically hatch at age 6 days, but they can hatch as early as 4 days if attacked by egg predators. Early hatchlings are less developed and more vulnerable to predatory shrimp and fish. Here we assess the effect of hatching timing on risk of predation by three common insects, with different foraging styles, that prey on red-eyed treefrog larvae. Further, we examine whether the consequences of hatching early vary with the presence of later-hatched tadpoles. We induced hatching at 4 and 6 days and exposed tadpoles to giant water bugs or aeshnid or libellulid dragonfly larvae over 24 hrs, quantifying tadpole behavior and mortality. We used substitutive designs with three treatments: early hatched, late hatched and mixed hatching ages. In no case did presence of the other age class alter mortality. Hatching age did not affect libelullid predation, which was low in both cases. Early-hatched tadpoles had higher mortality than late hatchlings with water bugs, which move throughout the water column. In contrast, early hatchlings had lower mortality than late hatchlings with aeshnids, which cue strongly on movement. Late-hatched tadpoles were more active than early hatchlings, and movement was reduced in the presence of aeshnids. Combining across this and previously published studies, early hatchlings are more vulnerable than late hatchlings to most (3/5) predators. Variation in relative, age-specific hatchling vulnerability to predators with different foraging styles is consistent with developmental changes in tadpole behavior

Iron bioavailability in low-phytate pea

Non-Peer ReviewedPhytate is the main storage form of phosphorus in the seeds of most crops. Phytate is not well digested by monogastrics and it chelates iron, zinc and some other micronutrients. To increase the nutritional value of pea seeds, two low phytate lines (1-150-81 and 1-2347-144) were developed from CDC Bronco in previous research. In this study, an in vitro digestion/Caco-2 cell culture bioassay was used to simulate the iron absorption of peas in humans, as the cell line originated from human colon adenocarcinoma cells. The iron bioavailability of the two low-phytate lines was 1.4 to 1.9 times higher than that of three normal phytate varieties, while having the same total iron concentration. In vivo studies were used to evaluate iron absorption of chickens fed low phytate and normal phytate pea diets. The diets containing the two low-phytate pea lines had no significant effect on chicken body weight and hemoglobin level, compared with the diets containing normal phytate pea cultivars, however, iron deficiency was suspected in all diets used