Understanding Organisms Using Ecological Observatory Networks.

Human activities are rapidly changing ecosystems around the world. These changes have widespread implications for the preservation of biodiversity, agricultural productivity, prevalence of zoonotic diseases, and sociopolitical conflict. To understand and improve the predictive capacity for these and other biological phenomena, some scientists are now relying on observatory networks, which are often composed of systems of sensors, teams of field researchers, and databases of abiotic and biotic measurements across multiple temporal and spatial scales. One well-known example is NEON, the US-based National Ecological Observatory Network. Although NEON and similar networks have informed studies of population, community, and ecosystem ecology for years, they have been minimally used by organismal biologists. NEON provides organismal biologists, in particular those interested in NEON's focal taxa, with an unprecedented opportunity to study phenomena such as range expansions, disease epidemics, invasive species colonization, macrophysiology, and other biological processes that fundamentally involve organismal variation. Here, we use NEON as an exemplar of the promise of observatory networks for understanding the causes and consequences of morphological, behavioral, molecular, and physiological variation among individual organisms.

A hybrid zone and bidirectional introgression between two catadromous species: Australian bass Macquaria novemaculeata and estuary perch Macquaria colonorum.

The presence and distribution of hybrid individuals and the existence of a hybrid zone between the catadromous Australian bass Macquaria novemaculeata and estuary perch Macquaria colonorum were investigated throughout the range of both species in Australia. Bayesian analyses and genotypic simulations identified 140 putative hybrids (11·5% of the total sample) with varying levels of introgression. Most hybrids were observed in an area extending from the Snowy River to the Albert River suggesting a hybrid zone in the eastern Bass Strait region. Sixteen hybrids, however, were found outside this zone, possibly reflecting the movement of hybrid offspring between estuaries or their inadvertent release during fish stocking programmes. Biparental backcrossing was found to occur suggesting that hybrids were fertile. These results have implications for the management of the extensive stocking programme in M. novemaculeata and for understanding the potential role of habitat degradation and reduced water flow in facilitating hybridization in species with migratory life histories.

Complex selection associated with Hox genes in a natural population of lizards.

Hox genes are recognized for their explanatory power of bilateral development. However, relatively little is known about natural variation in, and the evolutionary dynamics of, Hox genes within wild populations. Utilizing a natural population of sand lizards (Lacerta agilis), we screened HoxA13 for genetic variation and an association with incidence of offspring malformations. We found significant effects of parental genetic similarity and offspring sex, and their interaction, on risk of hatching malformed as an offspring. We also found within population genetic variation in HoxA13, and identified a significant effect of a three-way interaction among Hox genotype, parental genetic similarity, and offspring sex on the risk of hatching malformation. Since malformed offspring in this population do not survive to maturity, this study reveals complex and ongoing selection associated with Hox genes in a wild reptile population. Importantly, this demonstrates the utility of natural populations in unveiling microevolutionary processes shaping variation in highly conserved genes.

Do catecholamines play a physiologic role in regulating corpus luteum function in the pseudopregnant rabbit?

In these studies the beta-adrenergic receptor antagonist propranolol was administered to estrogen-treated hypophysectomized pseudopregnant rabbits in vivo, and serum progesterone concentrations were measured to monitor luteal function. In Experiment 1, which was designed to determine an effective dose of propranolol, 1 mg/(kg X h) s.c. propranolol for 3 h (integral of 80 ng/ml in serum) gave an adequate level of beta-adrenergic receptor blockade, i.e., a 1000-fold inhibition of the blood pressure/isoproterenol dose-response relationship. In Experiment 2, "acute" administration of propranolol (P; 1 mg/(kg X h) s.c.) or saline (control, C) for 24 h on Days 7-8, 10-11, and 13-14 of pseudopregnancy did not produce any marked differences in serum progesterone concentrations in P or C animals on any of the days tested, although hourly fluctuations were observed. In Experiment 3, "chronic" (4-day) treatment with propranolol was achieved by the use of propranolol-containing pellets placed s.c. (integral of 200-600 ng/ml in serum), on Days 13-17. Control animals received pellets of vehicle only. Serum progesterone concentrations were very similar in P and C animals throughout the period of treatment (Days 13-17) and on Days 18 and 20. We conclude that endogenous catecholamines play no major role in regulating luteal steroidogenesis or corpus luteum regression in the pseudopregnant rabbit.